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194 Cards in this Set
- Front
- Back
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What are the two pathogenic Bacillus species?
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Bacillus anthracis and Bacillus cereus
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Bacillus anthracis:
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Only bacteria with a poly D- glutamic acid capsid (protein): protects against phagocytosis.
- Causes anthrax - Makes spores |
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Characteristics of Bacillus anthracis spores:
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- very stable
- resistant to drying - resistant to heat, ultraviolet light, disinfectants - the spores germinate and make toxins - spores protect in bad environments - humans exposed to spores through animal or soil, respiratory or cutaneous |
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What are the characteristics of the bacillus anthracis exotoxin?
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Excoded on pX01 plasmid: which the virulence factors transcribed optimally:
37 degrees Celsius CO2 Serum proteins - all in the human body. Make 3 proteins: Edema factor: disrupts H20 Homeostasis Protective Factor: promotes EF enry Lethal Factor: zinc metallic protease, inactivates protein kinase PX02 Plasmid: encodes capsule genes (unique protein one) - NEED BOTH PLASMIDS FOR VIRULENCE |
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What are the preventions and treatment of anthrax?
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RAPID treatment with:
Penicillin doxycyclin ciprofloxacin lerofloxacin High mortality if not fast Vaccine is available for humans, sometimes animals. |
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Bacillus cereus:
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Found: soil, mud, rice
Causes: food poisoning when spores in food product, bacteria then germinate |
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How is Bacillus cereus different from Bacillus anthracis?
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- motile
- non encapsulated - penicillin resistant |
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What are the two types of enterotoxins that cause illness in Bacillus cereus? Characteristics?
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Heat Labile:
Nausea, abdominal pain, diarrhea 12-24 hrs. Heat stable: SEVERE nausea and vomiting short incubation Antibiotics will not help because preformed toxins cause illness. |
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What are the characteristics of the Clostridium species? How do they differ from Bacillus?
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Gram positive
Spore forming rods The big difference Anaerobic (helps telling difference in lab from spore forming rods- Bacillus) - Extremely powerful exotoxins |
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What causes Clostridium botulinum?
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- homemade canned foods (likes anaerobic condition
- smoked fish - raw meats Infants: fresh honey |
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Which population is very effected by Clostridium botulinum?
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Canadian inuit population
- high number in ocean (whale, dolphins....) - eat raw meats - Isolated population without treatment, high fatality |
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Explain the clostridium botulinum toxin:
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Rapidly fatal food poisoning, neurotoxin.
- Blocks Ach release into autonomic system. Flaccid muscle paralysis: - afebrile - bilateral cranial nerve paraylsi - double vision - difficulty swallowing - general muscle weakness * respiratory paralysis --> death |
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How do you prevent Clostridium botulinum?
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- Proper cooking destroys spores
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Infant Botulism:
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When live bacteria is consumed (adults not affected)
- fresh honey with spores 1. Spores germinate in intestinal tract 2. neurotoxin released 3. 2-3 days of constipation, difficulty swallowing, muscle weakness SIDs ( Sudden infant death syndrome) |
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What is the treatment for botulism?
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Antitoxin-- which netralizes unbound free neurotoxin in bloodstream
- Respiratory support until muscles regained |
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What do you get Clostridium tetani from?
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Rusty nail which is contaminated with spores or animal feces
- wounds provide anaerobic environment |
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Describe the Clostridium tetani exotoxin?
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Tetanospasim--> sustained skeletal muscle contraction
- tetanus toxin taken up at neuromuscular junction ---> transported to CNS 1. Acts on inhibitor Renshaw interneurons -preventing release of GABA and glycine 2. Inhinbition of inhinbatory neurons allows motor neuron to send a high frequency of impulses 3. Sustained tetany - Clinical presentation of tetanus includes: - severe muscle spasms - trisnus - lock jaw - grotesque grinning * High mortality when lock jaw stage reached |
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What are the good uses of botulism?
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Good Uses:
-botox=type A - Botox was first approved in 1989 - treats eye muscle disorder -uncontroable blinking -excessive sweating -treatment for chronic pain -jaw tension -migrain headaches -muscle spasms |
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What is the vaccine for Clostridium tetani?
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DPT (diphtheria- pertassi- tetanus) shot given with
Formulin- inactivated toxin every 10 yrs as booster |
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What does Clostridium perfringens cause? characteristics?
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- Gas Gangrene
- Spore mature in anaerobic conditions + produce gas - devastated soldiers wounded in battle - 2 classes of infection |
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What are the 2 classes of infection in Clostridium perfringens? Characteristics?
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1. Cellulitis/ wound infection:
- Necrotic skin exposed to bacteria - grows and damages local tissue - palpitation reveals moist, spongy, crackling consistency to skin due to pockets of gas 2. Clostridial myonecrosis - when inoculated with trauma into muscles, secretes exotoxins that destroy adjacent muscle - results in gas formation when carbs fermented from action of enzymes - Ct scan shows pockets of gas - as muscle degrades: blackish fluid comes from skin |
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What is the treatment of Clostridium perfringens?
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- Fatal unless identified early and treated early
- hyperbaric oxygen and antibiotic (penicillin) - Remove necrotic tissue |
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What causes Clostridium difficile? Why?
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More common in hospitals than anthrax, tetanus or botulism.
Causes: anitbiotic- associated pseudomembranous enterocolitis Why? arises from over use of broad spectrum antibiotics which destroy the normal flora In the intestinal tract. (ampicillin, clindamycin, cephalosporins) |
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What are the toxins Clostridium difficile produces?
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C. Difficile superinfects the colon, where it can release exotoxins
Toxin A: causes diarrhea Toxin B: cytoxic to colonic cells. Severe diarrhea, abdominal cramping and fever |
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What is the treatment for C. Difficile?
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- Possible cause of patients with diarrhea while on antibiotics. (stool with toxin for confirmation)
1. Discontinue initial antibiotic regimen 2. Adminiter metronidazole or vancomycin by mouth, since they are not absorbed orally into bloodstream. |
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What are the two medically important non-spore- forming rods?
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Listeria monocytogenes and Corynebacterium diphtheriae.
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What does Listeria monocytogenes cause?
Caused by? |
- Listeriosis
- immunocompromised and elderly at risk, young, AIDS, transplant - soft cheeses, unpasteurized milk, cold cuts, pâté |
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What does it mean that Listeria monocytogensis is facultative intracellular organism?
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It can live outside or within cells
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What are the clinical manifestation of Listeria m.
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- One of few bacteria that can cross the 3 protective barriers:
1. Blood- brain 2. Gastrointestinal 3. feto- placental - Psychrophile: capable of reproduction in cold temperatures (fridge, freezer) - Variety of Symptoms: General malaise, to meningitis to spontaneous abortions. |
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What is the treatment of Listeria m?
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No antimicrobial resistance
- treat with ampicillin or trimethoprim- sulfamethoxazole |
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What does Corynebacterium diphtheriae cause? which does?
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Causes Diphtheria which colonizes the pharynx, and forms a grayish pseudomembrane composed of fibrin, leukocytes, necrotic epithelial cells and C. diphtheriae cells
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What does the Corynebacterium Diphtheriae exotoxin do?
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Bacteria releases exotoxin into bloodstream.
- damages heart and neural cells by interfering with protein synthesis. |
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What is the treatment for C. Diphtheriae?
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3 steps:
1. Antitoxin to inactivate circulating toxin 2. Penicillin or erythromycin to kill bacteria 3. DPT vaccine - Can be lysogenized by a temperate bacteriophage, which codes for exotoxin, which contains two subunits. B will bind and help A enter, A will block protein synthesis |
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What are the general facts of the enteric gram negative bacilli?
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- part of normal intestinal flora, BUT can cause disease
- 4 main groups - divided based on biochemical and antigenic properties |
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Name the important growth medias in classifying enteric gram negative bacilli.
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1. Ability to ferment lactose to gas and acid.
EMB media: Lactose fermenter: -dark purple /black - inhibits gram positive MacConkey agar: - Bile salts inhibit gram + - Lactose fermenters develop pink- purple coloration SELECTIVE/ DIFFERENTIAL MEDIA |
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Which enterobacteria ferment lactose? which dont?
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Ferment: enterioobacteriaceae
Dont: Salmonella, shigella, pseudomonas |
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Name the biochemical factors in classifying enteric gram negative bacilli.
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- production of H2S
- Ability to hydrolyze urea - Liquefy gelatin - decarboxylate specific amino acids |
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What classifications of enterics can you make with cell surface antigens?
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3 major:
1. 0 antigen: most external component of LPS (differs between them) 2. K antigen: this is a capsule that covers the O 3. H antigen: flagella subunit. Only in motile bacteria |
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What types of diarrhea diseases do enterics cause?
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1.a Diarrhea- with or without systermic invasion
1. b diarrhea with invasion of intestinal epithelial cells 1. c Diarrhea with invasion of lymph nodes and bloodstream |
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1.a Diarrhea- with or without systermic invasion:
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- no cell invasion- bacteria bind to intestinal epithelial cells, but do not enter
- diarrhea caused by release of exotoxins - cause electrolyte and fluid loss - watery diarrhea without systemic symptoms (fever) Ex: v. cholera |
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1. b diarrhea with invasion of intestinal epithelial cells
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- Cell invaded
- Toxins destroy cells - Systemic response - Cell death results in bloody stools - ex: e. coli O157:H7 |
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1. c Diarrhea with invasion of lymph nodes and bloodstream
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- Ab pain and diarrhea with white and red cells
- fever, headache, increased white cell counts ex: Salmonella |
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What various other infections do enterics cause?
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- Urinary tract infections, pneumonia, bacteremia, sepsis
- Hospital settings: nosocomial infections |
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What are some general characteristics of Salmonella?
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- Two Species, with multiple serovars.
S. enterica: Differentiated based on biochemical traits and S. bongori. over 2541 serovars! |
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What two Salmonella infections are in humans?
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Enterocolitis (S. enterica)
Enteric Fever: (aka Typhoid) Septicemia fever osteomyletis |
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What is the pathogenesis of Enterocolitis caused by S. enterica serovar Entriditis?
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Severity of infection influenced by:
- dose of ingested organisms - State of host: ( high incidence in yound, elderly, people with preexposed conditions) Short incubation period: - 6-48 hrs, usually 8-12h - colonize mucosa of small intestine and colon = inflammation with mononuclear response |
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What are the clinical findings of Enterocolitis caused by S. enterica serovar Entriditis?
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- nausea, vominting, profuse diarrhea, ab pain
- fever, chills, headache, myalgia, - 2-3 day recovery - Rare: septicemia |
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What is the lab culture of Enterocolitis caused by S. enterica serovar Entriditis?
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stool culture
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Where do you get an infection of Enterocolitis caused by S. enterica serovar Entriditis?
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- ingestion of food/ drink contaminated
- animal products, - person to person - most occur at home, - many go unreported |
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What is the treatment of Enterocolitis caused by S. enterica serovar Entriditis?
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- anitmicrobials NOT recommended.
- can just prolong excretion of organisms, does not shorten illness. - immune system can handle it |
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What are the two bacteria that give you Enteric Fever?
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1. S. enterica serovar Typhi causes Typhoid
2. S. entrica serovar Paratyphi causes Paratyphoid fever |
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What is the pathogenesis of Enteric fever?
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- severe generalized infection
- x in the lymphoid tissue. - intestinal epithelium invasion followed by x in lymph nodes and entry to blood stream. -Hyperplasia and necrosis of intestinal lymphoid tissue lead to: ulceration, haemorrhage, or perforation. - if untreated: mortality about 10%. Survivors: 1. convalescent carriers: passable for 3 months 2. Chronic (1-2%) lasting over 6months or lifelong. |
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What is the lab diagnosis of Enteric fever?
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- isolation from blood- 1st week
- stool and urine- 2nd and 3rd week |
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What is the epidemiology of Enteric fever?
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- Humans only known carrier
- Major vehicles: sewage water, shellfish, milk - chronic carriers maintain endemic |
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What is the way to prevent Enteric fever?
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- sanitary disposal of human faeces
- scrupulous cleanliness: handling food, - water purification - some vaccines protect against small portion |
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What are some characteristics of Escherichia Coli?
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- Gram - bacilli
- lactose fermenters - most numerous species of normal human flora - harmless in intestine, pathogenic EVERYWHERE else. Most frequent urinary tract |
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Enteropathogenic E. coli:
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- severe diarrhea in infants, developing countries
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Enterotoxigenic E. coli:
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- major cause of infantile diarrhea in developing countries
- most frequent cause of TD |
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Enteroinvasive E.coli
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- non-bloody diarrhea
- dysentery - similar to Shigella |
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diffuse- adhering E. coli
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- diarrhea in yougn children
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enteroaggregative E. coli:
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subtype
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Enterohemorrhagic E.coli:
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- recognized as human pathogen in 1982 colitis outbreak
- E. coli O157 most common cause: -hamburger disease, proper food handling will prevent - verotoxins or shiga toxins: - associated with: severe and sometimes fatal condition: hemolytic uremic syndrome |
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Describe Shigellae.
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- gram negative bacilli
- generally NOT lactose fermenters - found in human gastrointestinal tract Causes: acute diarrhea (with mucous, pus and blood if severe) |
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Name the three species of Shigella and where they are most common. What kind of illness do they cause?
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Shigella sonnei and
S. flexneri: found mainly in europe and NA. Cause mild illness Shigella dysenteriae: found mainly in tropics, causes severe illness - invasion of epithilial mucosa of colon= watery diarrhea, craps, fever. - infection with ingestion of small number. |
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What is the epidemiology of Shigella?
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- most frequent (2 thirds) in children under 10
- poor sanitation and crowding - bacteria usually disappear from stool within a month - short carrier state |
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How do you prevent Shigella?
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- similar to typhoid
- no vaccine |
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Describe Vibrio cholerae
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- comma shaped gram - bacteria
- produces enterotoxin (cholera toxin) which binds to epithelial cells in the small intestine= secrete chlorides and decrease sodium absorption - water accumulates in lumen= diarrhea - can lead to severe dehydration if untreated = death |
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Where do you find Vibrio cholerae? why?
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- endemic in Southeast asia
- parts of africa - Lack of clean drinking water - waterborne infection |
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What are the two types of Campylobacter bacteria? which is the more common human pathogen?
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Campylobacter jejuni: more common human pathogen
Campylobacter coli: more common in animals MAJOR cause of human enteritis - some invasive, others toxigenic |
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What does Campylobacter cause?
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- fever
- ab pain - bloody diarrhea - can be an agent of TD |
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How do you culture Campylobacter?
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- stool culture
- inoculated on special media, requires reduced oxygen tension and CO2 |
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Describe the Peseudomonas:
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- free living
- gram - rods - cause illness in compromised patients - moist habitats: like humidifiers |
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Why are Pseudomonas so hard to treat?
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- they are resistant to many antibiotics.
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Describe Pseudomonas aeruginosa:
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- most common species.
- Respiratory pathogen with cystic fibrosis - Pathogen related to skin burns |
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Describe Pseudomonas cepacia:
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- ability to multiply in low nutrient environments
- commonly contaminates saline and water solutions - respiratory pathogen in cystic fibrosis |
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Describe Haemophilus influenzae:
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- Part of normal flora of nasopharyngeal in adults and children
- Pathogenic in two situations 1. Invasive infections in young children: meningitis, pneumonia, joint infections - this is disappearing from canada, because vaccine now available 2. Haemophilus influenzae is also associated with: increased bronchial infection in people with chronic bronchitis |
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Describe Enterobacter SPP.
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- may colonize and infect hospitalized patients
- causes wound infections, bacteremia and hospital- acquired pneumonia - may be resistant to antibiotics - E. sakazakii linked to outbreaks of contaminated powered infant formula |
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Describe Helicobacter pylori:
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- microaerophilic
- spiral bacilli - non spore forming |
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What does Helicobacter pylori cause?
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- Most common cause of duodenal ulcers and
- chronic gastritis (inflamed stomach) |
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What happens in a Helicobacter pylori infection? How is it treated?
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- releases urease, which raises the pH locally ( which protects them from acidity of stomach)
- Pepto bismol contains bismuth salts, known to inhibit H. Pylori Treat: - antibiotics combined with - proton pump inhibitor (triple therapy) - (amoxicillin, metronidazole, omeprazole) |
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What does Bordetella pertussis cause?
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- Whooping cough
- because of destroyed ciliated cells in trachea and bronchi |
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What are the 4 virulence factors in Bordetella pertussis?
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1. Pertussis toxin ( A-B toxin)
2. Extra cytoplasmic adenylate cyclase which weakens host cells defenses 3. Filamentous hemagglutinin which attached to ciliated cells of bronchi + releases exotoxin 4. tracheal cytotoxin: destroys ciliated epithelial cells and causes impaired clearance of bacteria, mucus buildup, and inflammatory exudates |
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Is there a vaccine for Bordetella pertussis?
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- yes, heat- killed organism
- part of the DPT vaccine |
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Describe Legionella: what does is cause? where is is found? how is it transmitted?
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- Causes legionnaires disease
- opportunistic - grows in water; found on shower heads and water tanks - exposure only by aerosol, can only get from environment, NO person to person transmission |
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What does parasite mean?
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- an obligatory symbiotic relationship between 2 organisms of different species
- the parasite is metabolically dependent on the host - Short term (mosquito) or - permanent (tape worm) - this is a very common way of life (50% of all animal species) |
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What are the modes of transmission for parasites?
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- Person to person (faecal- oral)
- water - food - zoonotic - insect vectors - blood or organ transplant - congenital - skin penetration |
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What does Giardia lamblia cause?
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- most are asymptomatic carries
Acute giardiasis: diarrhea weight loss ab discomfort nausea vomiting - can cause retardation of growth and development in children (cant thrive) - 1-4 weeks of incubation |
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What is the prevalence of Giardia lamblia? Why
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- most common protozoan infection of intestinal tract worldwide
- high prevalence in kids - High risk to immuncomprimised and travelers - low sanitation, trophozoites become cysts in stool and ingested |
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How do you diagnose G. lamblia?
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Microscopy
- of cysts in stool - bright field, immunoflorecence microscopy - immunological testing |
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What is the treatment of Giardia lamblia?
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Nitroimidazole derivatives
- some drug resistance |
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What are the way to prevent G. lamblia infections?
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Water treatment:
- resistance to chlorination - fewer outbreaks where there is water filtration - ozone / UV light promising - EPA method Public Health Education: - awareness; person to person, hygienic practices - found borne infections - dont drink raw surface water - traveling advice |
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Describe Trichomonas vaginalis:
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- 200 million cases worldwide (may be most common STD_
- transmitted through mucous membrane contact |
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What are the symptoms of Trichomonas vaginalis:
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- 40-50% asymptomatic carriage
- Vaginitis: itching, foul smell, sometimes frothy discharge - can increase cervical cancer and HIV - Pregnancy infection can result in premature delivery and low birth weight Males: usually asymptomatic, can: urethritis, prostatitis |
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How do you diagnose Trichomonas vaginalis?
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Microscopy (wet mounts)
- to identify in vaginal or urethral discharge - can be cultivated |
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How do you treat Trichomonas vaginalis?
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- metronidazole and tinidazole are the main drugs
- to avoid re-infection: testing and treating of both partners important - world wide |
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what are the symptoms of Entamoeba histolytica?
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Typical infections of the large intestine
- can be asymptomatic or - diarrhea and constipation - amoebic dysentery in some (bloody-mucoid diarrhea) - can spread through the blood and produce liver, lung or brain abscesses |
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How is Entamoeba histolytica diagnosed?
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microscopic identification of trophozoites or cysts in lesions or feces
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How is Entamoeba histolytica treated?
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Luminal amoebicides act on organisms in the intestinal lumen
- for symptomatic intestinal disease or extraintestinal infections, dug choice= metronidazole or tinidazole - then luminal amoebicides |
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What is the epidemiology of Entamoeba histolytica? How do we prevent it?
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Worldwide areas of poor sanitation, clinical disease in tropics.
Spread by water, vegetables, flies, food handles. - Public health education, Improved sanitation - wash fruits and vegetables |
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Describe Toxoplasma gondii and its hosts:
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- Large number of mammals and birds= intermediate hosts
- cats = definitive hosts because they shed oocysts Which causes: toxoplasmosis |
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How is Toxoplasma gondii transmitted?
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1. Ingestion of sporulated oocysts
- contaminated soil or sand - veggies - waterborne outbreaks 2. Ingestion of tissue cysts - raw or poorly cooked meats 3. Congenital fetus infection - most severe in first trimester |
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What are the symptoms of toxoplasmosis?
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1. Immunocompetent host
- 90% asymptomatic - lymphadenopathy - headaches / muscle aches - fever - malaise 2. Immunocomprmised - ecehalitis - myocarditis - pneumonia 3. Congenital - mental retardation - hepatosplenomegaly - retinochoroiditis - hydrocephalus |
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What is the treatment for toxoplasmosis? How is it diagnosed?
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Diagnosis:
- serological - mouse inoculation Treatment: - immunocompetent not needed - Compromised: prompt treatment- combination of pyrimethamine and sulfadiazine Congenital: - mother and fetus treated to reduce incidence/ severity - newborns can be treated |
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What preventions can be made agaisnt toxoplasmosis ?
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1. Cats should not eat raw meat, or catch prey
2. Pregnancy considerations 3. Dispose of kitter litter daily 4. Wash hands 5. Wash freash fruits and vegetables 6. through cooking of meats |
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Describe the different species of Plasmodium.
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Plasmodium falciparum: most common and severe
Plasmodium vivax: dormant liver stage, can relapse Plasmodium ovale: another dormant liver stage Plasmodium malariae: Asymptomatic infections can last a lifetime |
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What is Plasmodium? How is it transmitted?
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Plasmodium is Malaria
Transmission: Anopheline mosquitos Blood transfusion / needles Congenital Airport malaria |
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What are the symptoms of Malaria?
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- spiking fever and chills
- sweating - flu like symptoms: headaches, ab pain, malaise - Severe symptoms: seizures come renal failure respiratory failure |
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How is Malaria diagnosed?
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- blood smears stained with giemsa
- collect blood just before fever peaks |
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What is the epidemiology of Malaria?
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- Sporozoites introduced through mosquito bites.
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What it the prophylaxis of malaria?
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- Anitmalarials should be taken before reaching endemic area and continue after returning
- Choloquine and mefloquine are drugs of choice - resistance a big problem |
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How do we control Malaria?
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- man made disease, deforestation .....
- Need eradication of control of mosquitoes - Protection against mosquitoes at night |
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Describe Cryptosporidium. Symptoms? Treatment?
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- lots of species
- Cryptosporidiosis causes: -watery diarrhea - dehydration - weight loss - ab pain - fever - nausea - vomiting - Immunocomprimised: -chronic, debilitating and possibly fatal symptoms - NO DRUGS |
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How does Cryptosporidium get transmitted?
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Water
- drinking - water parks and pools |
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How does Cryptosporidium parvum get transmitted?
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Person to Person
- poor hygiene Autoinfection - thin walled oocysts released into lumen cause auto infection - chronic and life threatening for immunocompromised Zoonotic: - cattle host - diarrhea in calves - environmental contamination; veterinary personnel |
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How do you diagnose C. parvum?
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Microscopy:
- stools with shedded oocysts - concentration methods - wet mounts - immunofluorescence microscopy |
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How do you control C. parvum
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- sand filtration
- chlorination - Ozone, UV light - EPA method water testing Public Health Education: - in endemic areas, avoid drinking tap water, raw fruits and vegetables - immunocompromised = bottled water - 60 degrees plus and 20 below kills oocysts - handwashing |
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What are the symptoms of Cyclosporiasis?
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- low infectious dose
- 1 week incubation - Profuse and prolonged diarrhea - Ab pain, nausea, vomiting, fatigue, fever, loss of appetite |
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How is Cyclosporiasis treated?
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- bactrim ( trimethoprim- sulfamethoxazole)
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How is Cyclosporiasis diagnosed?
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Microscopic exam:
-wet mount - stool for oocysts - staining methods |
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How is Cyclosporiasis transmitted?
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Unlikely:
- person to person - Zoonotic Waterborne and Food borne Direct: infected food handlers Indirect: water used for irrigations, mixing pesticides, washing equipment, hands |
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What are metazoa?
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- multicellular parasites
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Describe Enterobium vermicularis (pinworm):
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- a nematode
- world wide - high incidence in school age children - nuisance |
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What are the symptoms of Enterobium vermicularis?
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- milf caesum/ colon infection
- can cause itching (pruritus ani) leading to disturbed sleep, irritability - scratching can cause secondary infections |
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How do you diagnose pinworm? Treat?
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- scotch tape test of perianal area
- Microscopy identification of eggs, (adult female worms can be present) treatment: - pyrantel pamoate |
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How do you control pinworm?
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- Hygiene education for kids
- discourage scratching, nail biting - bathing, change of clothes and underclothing |
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Describe what and where Trichinella spp. is; how is it transmitted?
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- small roundworm found world wide in many carnivorous and omnivorous animals, Humans
- Transmitted by ingestion of larvae in raw or poorly cooked meat - survives as adult in small intestine, as larvae in striated muscle |
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Compare Trichinella spiralis and Trichnella nativa:
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Trichinella spiralis:
-domestic form - humans, swine, rats - horses Trichinella nativa: - wild form - humans, -bears, wild boar, wolf, fox, walrus |
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What does Trichinella cause? Symptoms?
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- trichinosis
Symptoms: Depend on stage in lifecycle Larvae: excyst in small intestine= - diarrhea - ab pain - vomit Next generation of larvae migrate into muscle tissues: - facial edema - conjunctivitis - fever Occasional Life threatening: - myocarditis - CNS - pneumonitis -myalgia |
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How is Trichinosis treated?
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- Intestinal phase: thiabendazole
- Tissue Phase: Mebendozole and albendazole Steroids to reduce inflammation |
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How is Trichinosis Controlled?
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- Rodent control
- no garbage feeding livestock - inspection programs - cooking and freezing |
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Describe Ascaris lumbricoides:
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- large intestinal nematode
- High prevalence worldwide (warmer regions higher) - nematode |
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How is Acaris lumbricoides transmitted?
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- sheds with faeces, eggs mature and become infective
- ingestion of eggs in soil, fruits, water - poor sanitation |
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What are the symptoms of Ascaris lumbricoids?
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- can be asymptomatic
- vague ab discomfort -vomiting or obstruction can occur |
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How id Ascaris lumbricoides diagnosed? Treated?
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Microscopy:
- stool for eggs Treatment: - medendazole, albendazole, or pyrantel - Surgery may be required to clear worm bolus |
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Describe the Anisakis simplex (whale or herring worm)
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- high in japan
- rare NA - most arise from hoem prepared sushi, sashimi and ceviche |
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What are the hosts to the Anisakis simplex?
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Definitive:
- dolphins -whales, porpoises Intermediate: marine crustaceans Second Inter: - salmon, mackeral, cod, herring, tuna, squid HUMANS DEAD END HOSTS |
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What are the symptoms of Anisakiasis? Diagnosis? treatment? Control?
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- invasive and penetrate mucosa
- ab pain, nausea, vomiting - difficult diagnosis (no eggs in stool) - endoscopic and radiologic exams - Symptoms often mistaken for appendicitis -drugs not effective Control: - inspection of fillets at processing plant - candling on a light table reveals larvae - cooking and freezing effective |
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Describe Diphyllobothrium latum
(broad fish tapeworm) |
- Platyhelminths
- Cestodes ( tape worms) - inhibits small intestine of humans, and other fish eating mammals - larval stages in fresh water species , which act as inter hosts |
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How is Diphyllobothrium latum transmitted? Symptoms? Diagnosis? Treatment?
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- consumption of raw, badly cooked freshwater fishes
- many cases asymptomatic - ab pain, dizziness, fatigue, vomiting, diarrhea, - vitamen b12 deficiency - stool sample for eggs, - Anthelmintic drugs effective |
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Describe Taenia Spp. Symptoms? Diagnosis? Treatment?
|
- tapeworms
- Adult stage only - transmitted through ingestion of larvae in raw or poorly cooked meat Taenia saginata - beef tapeworm Taenia solium - pork Symptoms: mild ab complaints Diagnosis: eggs in stool, serological techniques Treatment: Anthelmintic drugs surgery |
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What is Taenia solium neurocysticercosis?
|
- infection with larval stage following ingestion of eggs,
- larvae migrate and develop in brain - Intracranial hypertension, hydocephalus - convulsive seizures |
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How do we control Taenia?
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- rare in canda
- routine inspections - cooking - where endemic: sanitation, prevent pigs access to human faeces |
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Describe Schistosoma spp.
(Blood flukes) |
- worldwide
- free swimming larvae in fresh water, pentrate skin, develop blood vessles surrounding intestine or bladder - 3 main species: S. haematobium, S japonicum S. mansoni |
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What are the symptoms of Schistosomiasis?
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- rare, except heavily infected
- rash, itchyness - fever, lymphandenopathy hepatosplenomegaly |
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How is schistosomiasis diagnosed? treated? controlled?
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- microscopic exam for eggs in feces or urine
- treated with praziquartel Control: -eliminate habitate for snails - spraying molleuscicides - better sanitation - avoid fresh water contact in endemic areas |
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Mycobacteria:
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- Causative agents of tuberculosis and leprosy
- waxy coat: no gram stain, resistant to disinfectants - Acid- fast bacilli - resist decolorization akz Ziehl- Neelsen stain |
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Describe the Ziehl Neelsen stain:
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1. carbol fuchsin to slide for 5 mins with heat
2. gentle wash with water, cool 3. acid alcohol is now added to decolorize 4. Wash slide again 5. Couterstain methylene clure for 1- 2 mins |
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Mycobacterium tuberculosis: transmission? diagnosis? characteristics? population infected?
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Chronic, slow -progressing pulmonary infection
- Transmission by aerosol droplets - obligate aerobe - facultative intracellular 4-6 weeks to see colonies on a plate. - lowenstein- jensen medium - use microscopy of sputum smears as first line of diagnosis - infection develops in stages - one third of worlds pop infected |
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Primary Tuberculosis:
|
Aerosol inhalation, bacteria multiply in alveoli,
- macrophage ingestion of bacilli and formation of primary complex - foci of infection in lungs can spread to kidneys, bones, meninges - CMI fully activated, infection is stopped - Some bacilli survive, reactivation several years later |
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Post- primary tuberculosis:
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- late reactivation of lesions in lungs, kidneys, bones
- 5%, higher in people with AIDS - chronic |
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What is a positive tuberculin test?
|
- when the latent infection and th active CMI is reflected
- Tuberculin is a protein obtained by concentrating and purifying the liquid culture medium in which the bacteria was growing |
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What happens in a small amount of cases with tuberculosis?
|
- pleural effusions
- miliary tuberculosis and or meningitis - tuberculous pneumonia |
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Immunity In tuberculosis:
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- Cell - mediated immunity is the most important (t-cells)
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Mantoux test:
|
- Tuberculin solution is injected INTRADERMALLY,
- 48-72 hours, check for redness Diameter: - 10mm plus POSITIVE - 5-9 mm Doubtful, may be cross reaction with other mycobacteria - less then 4 mm NEGATIVE ** POSITIVE TEST does not mean there is a current active infection |
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Lab diagnosis of Tuberculosis:
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Microscopic exam
- sputum smears Cultures- - special media - 3-6 weeks - positive cultures checked for sensitivity to antituberculous drugs |
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What are Atypical Mycobacteria? What are the types, and what do they cause?
|
- Non- tuberculous mycobacteria are occasionally isolated from patients with chronic pulmonary disease, indistinguishable from tuberculosis.
- these show higher resistance to antituberculous drugs M. scrofulaceum: causes lymphandenitis in children M. marinum: skin infections M. fortuitum: soft tissue abscesses. - Often responsible for doubtful manteux test. - typically seen in immunocompromised patients |
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What are the two types of leprosy and their characteristics caused by Mycobacterium leprae?
|
Tuberculoid leprosy:
- visible nerve enlargement - few erythmatous plaques - few bacilli in infected tissues - many lymphocytes and granulomas - LOW infectivity Lepromatous leprosy: - no visible never enlargement - many erythromatous nodules - many bacilli in infected tissue - HIGH infectivity |
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What is the epidemiology? Diagnosis? and Treatment of leprosy?
|
- not common in NA, mostly seen in Asia and Africa
- 1- 2 million cases each year - Transmission, human to human, rare cases: animals - microscopy for lepromatous, but skin for tuberculoid - Tuberculoid form: Dapsone combinded with rifampin - Lepromatous form: Dapsome, rifampin and clofazimine - Prompt treatment to stop spread. |
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Spirochetes:
|
- Spiral shaped
- gram - - including: Treponema Leptospira Borrrelia |
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Treponema pallidum:
|
Causes syphilis
- helical bacteria - Uncultivable in vivo - use dark field microscopy - almost invisible under gram stain |
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Primary Syphilis:
|
- chancre 3-4 weeks later
- fluid from lesions contain bacteria- seen under dark field microscopy |
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Secondary Syphilis:
|
- 6 weeks after appearance of chancre
- RASH - mucosal lesions with many with many trepnemes - can have spontaneous remission after 1 or 2 phase |
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Latent Syphilis:
|
- No symptoms
- non transmittable after 4 years - but congenital infection can happen |
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Late syphilis:
|
- Obliterative endarteritis
- Can involve skin, mucosae, nervous system, Cardiovascular system and tissue - organ damage |
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What methods of serological testing are used to see if someone has had syphilis in the past?
|
Non- treponemal tests
- non- specific - screening - early positives Treponemal tests - Specific: use treponemal extracts - Florescent treponemal antibody absorption - microhemaggultination of T. pallidum - no culture |
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how can syphilis be prevented?
|
- Sexual education
- periodic serological tests of individuals at high risk with subsequent treatment - pregnancy testing |
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What does Borrelia burgdorferi cause? how? Symptoms? Where is it found?
|
- causes: Lyme disease
- Tick bites - spirochete Symptoms: - affects skin, joints, nervous system and heart - common in US, rare in CAN |
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How is lyme disease diagnosed?
|
Serology:
- hard to see under microscope - no culture - serology does not give positive in first 2- 4 weeks of infection. |
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What is the clinical diagnosis of lyme disease?
|
- paitient has either or:
- eryhma migrans - late manifestation: ( musculoskeletal, NS, cardiovascular |
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How is lyme disease treated? prevented?
|
- Early lyme disease: doxycycline, amoxicillin or cefuroxime
- those with late, must undergo prolonged treatment Prevent: - avoid ticks and their habitat - wear protective clothing. Vaccine is available. ospA antigen of organism |
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What is Leptospira interrogans?
|
- causes sub- clinical infection, mild flu like illness, severe systemic disease
- Severity based on # of organisms - thin, highly motile, enter through cuts, abrasions, - blood stream and infect all tissues and CNS - few cases in NA, humans accidental end host -infection from contaminated water - IV penicillin or ampicillin for sever infections, - or oral for less severe |
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What are the characteristics of Clamydiae?
|
- obligate intracellular energy parasites
- cocci - CAN NOT MAKE their own ATP - can not be grown on artificial media Life cycle has two forms: - Elementary body (infections, no growth or replication) - Reticulate body (rep and growth) - 3 main species |
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Describe Chlamydia trachomatis? Symptoms? If if goes untreated?
|
- very common STD
Males: Urethritis Female: cervicitis - Many people asymptomattic and untreated because of limited diagnostic tools Untreated male: prostatitis, epididymitis Untreated female: PID--> tubal infertility, ectopic pregnancy, chronic pelvic pain |
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How is Chlamydia divided?
|
2 bivars: trachoma and LGV
Trachoma: 15 serovars, LGV; 4 serovars |
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What other infections does C. trachomatis cause?
|
Trachoma: chronic ocular infection (leading blindness cause in North Africa, middle eat and S. E asia)
- Perinatal transmission: conjunctivitis and less frequently pneumonia in the newborn - Lymphogranuloma venereum: STD from some serotypes. endemic in tropic and subtropic |
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What are the other types of Chlamydiae? What do they cause?
|
Chlamydia pneumoniae:
- respiratory tract infections - mild pneumonia - sub clinical - droplet spread Chlamydia psittaci: - bird pathogen can transmit to humans - pneumonia or endocarditis |
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What are mycoplasmas?
|
- Smallest free living bacterium
- saprophytes - normal flora; oropharynx and genital tract of humans and animals - lack true cell wall - some pathogenic |
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Mycoplasma pneumoniae:
|
- Primary cause of atypical pneumonia
- more common in younger people - RARELY complications: meningoencephalitis, myocarditis - Diagnosis usually clinical, lab would be serology - Treatment: Erythromycin or tetracycline |
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Genital Mycoplasma:
|
Mycoplasma hominis, Ureaplasma urealyticum
- part of normal genital flora - colonizations rates increase with number of sexual partners - can cause: urethritis, epididymitits, PID, postpardum fever - Infertility and premature birth???? |
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Why are fungal infections on the increase?
|
Modern world of AIDS, organ transplantation, chemotherapy causes immunocompromised people to be on the rise. The lowered CMIis responsible for the increased fungal infections
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What are fungi?
|
- eukaryotic organisms
- lack way of energy synthesis - need aerobic environment |
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Dimorphic fungi:
|
fungi that grow as either yeast or mold
|
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Hyphae:
|
threadlike,
- branching tubules composed of fungal cells attached end to end |
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Molds (mycelia):
|
- multicellular colonies composed of clumps of intertwined and branching hyphae
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Saprophytes:
|
- fungi that live and use organic matter such as soil, rotten vegetation as the energy source
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Spores:
|
reproducing bodies of molds
|
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Yeast:
|
- unicellular growth form of fungi
- spherical or ellipsoidal - reproduce by budding |
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|
Name the four skin depths fungal diseases infect:
|
Skin- superficial
Cutaneous Subcutaneous Systemic |
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|
Superficial fungal infections:
|
Malassezia furfur - hypo or hyperpigmented patches that remain white if you suntan
Exophiala werneckii - painless patches on soles of hands and feets Treatment: dandruff shampoo with selenium |
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Cutaneous fugal infections:
|
( skin hair nails)
- dermatophytic secrete enzyme keratinase, scaling of skin, loss of hair - jock itch, athletes foots, scalp - oral thrush, diaper rash, vaginitis - Treatment: topical imidazoles that keep skin dry |
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Subcutaneous fungal infections:
|
Sporothrix schenckii:
- gardeners - nodule - Treat: potassium iodide Phialophora and cladosporium - rotting woord - wart like -Treat: itraconazole and local excision |
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Systemic fungal infections:
|
- dimorphic fungii that grow as mycelial form, with spors at 25 degrees on Sabourans agar
- 37 degress on blood agar, yeast - dimorphism makes them pathogenic ( in soil they are mycelia and release spores, inhaled by humans, now grow as yeast 3 cause systemic disease in humans Histoplasma capsulatum Blastomyces dermatitidis Coccidioides immitis |
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|
What is the mechanism of disease for the 3 systemic pathogenic human fungi? Clinical presentations?
|
1. Acquired by inhalation (spores)
- no person to person transmission Local infection in lung, then bloodstram 3: 1. asymptomatic 2. pneumonia 3. disseminated |
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Aspergillis flavus:
|
- Spores of this mold everywhere
- Some develop type 1 hypersensitivity reaction - persons with lung cavitation from TB or malingnancies can get aspergillus fungal ball in cavity - immunocompromised people can develop invasive and disseminated diseases, pneumonias A. falvus and others produce toxins called mycotoxins - aflatoxin: penuts, grains, and rice |
