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77 Cards in this Set
- Front
- Back
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Hemolysins
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(α, β, γ, δ) – lyse red blood cells
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Leukocidin
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lyses neutrophils and macrophages
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Enterotoxin
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induce gastrointestinal distress
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Exfoliative toxin
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separates the epidermis from the dermis
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Toxic shock syndrome toxin (TSST)
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induces fever, vomiting, shock, systemic organ damage
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Coagulase
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coagulates plasma and blood; produced by 97% of human isolates; diagnostic
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Hyaluronidase
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digests connective tissue
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Staphylokinase
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digests blood clots
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DNase
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digests DNA
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Lipases
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digest oils; enhances colonization on skin
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Penicillinase
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inactivates penicillin
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Gram Positive Cocci
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Staphylococcus aureus
S. epidermidis |
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Staphylococcus aureus
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Increase in community acquired methicillin resistance - MRSA.
Furuncle Carbuncle Impetigo Osteomyelitis Bacteremia Food intoxication Staphylococcal scalded skin syndrome Toxic shock syndrome |
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Localized cutaneous infections
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invade skin through wounds, follicles, or glands
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Furuncle
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boil; inflammation of hair follicle or sebaceous gland progresses into abscess or pustule
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Carbuncle
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larger and deeper lesion created by aggregation and interconnection of a cluster of furuncles
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Impetigo
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bubble-like swellings that can break and peel away; most common in newborns
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Osteomyelitis
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infection is established in the metaphysis; abscess forms
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Bacteremia
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primary origin is bacteria from another infected site or medical devices; endocarditis possible
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Food intoxication
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ingestion of heat stable enterotoxins; gastrointestinal distress
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Staphylococcal scalded skin syndrome
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toxin induces bright red flush, blisters, then desquamation of the epidermis
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Toxic shock syndrome
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toxemia leading to shock and organ failure
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Streptococci
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Lancefield classification system based on cell wall Antigenic factors (Ag) groups (A, B, C,….).
Another classification system is based on hemolysis reactions. Impetigo (pyoderma) Impetigo (pyoderma) –Erysipelas Streptococcal pharyngitis Scarlet fever Septicemia Pneumonia Streptococcal toxic shock syndrome Rheumatic fever Acute glomerulonephritis Causes 60-70% of all bacterial pneumonias. |
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Impetigo (pyoderma)
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superficial lesions that break and form highly contagious crust; often occurs in epidemics in school children; also associated with insect bites, poor hygiene, and crowded living conditions
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Impetigo (pyoderma) –Erysipelas
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pathogen enters through a break in the skin and eventually spreads to the dermis and subcutaneous tissues; can remain superficial or become systemic
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Streptococcal pharyngitis
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strep throat
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Scarlet fever
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strain of S. pyogenes carrying a prophage that codes for erythrogenic toxin; can lead to sequelae
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Rheumatic fever
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follows overt or subclinical pharyngitis in children; carditis with extensive valve damage possible, arthritis, chorea, fever
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Acute glomerulonephritis
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nephritis, increased blood pressure, occasionally heart failure; can become chronic leading to kidney failure
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Gram Negative Cocci
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Neisseria gonorrhoeae
Neisseria meningitidis |
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Neisseria gonorrhoeae
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Strict parasites.
Causes gonorrhea, an STD Strictly a human infection. In top 5 STDs. 20-30% of new cases are penicillinase-producing PPNG or tetracycline resistant TRNG. |
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Neisseria meningitidis
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Prevalent cause of meningitis; sporadic or epidemic.
Human reservoir – nasopharynx; High risk individuals are those living in close quarters, Disease begins when bacteria enter bloodstream, cross the blood-brain barrier, permeate the meninges, and grow in the cerebrospinal fluid. Very rapid onset; neurological symptoms; endotoxin causes hemorrhage and shock; can be fatal. |
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Gram Positive Bacilli
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Genus Bacillus
Genus Clostridium Listeria monocytogenes Corynebacterium Diptheriae Mycobacterium Tuberculosis Mycobacterium Leprae Actinomyces & Nocardia |
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Medically Important Gram-Positive Bacilli
Three general groups: |
1. Endospore-formers
2. Non-endospore-formers 3. Irregular shaped and staining properties |
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Spore-Forming Bacilli
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Genus Bacillus
anthracis cereus Genus Clostridium perfringens difficile tetani botulinum |
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Bacillus Anthracis
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Central spores that develop under all conditions except in the living body
3 types of anthrax: Cutaneous – spores enter through skin, black sore- eschar; least dangerous Pulmonary –inhalation of spores Gastrointestinal – ingested spores Treated with penicillin, tetracycline, or ciprofloxacin Vaccines |
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Bacillus Cereus
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Grows in foods, spores survive cooking and reheating
No treatment but self limiting |
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Genus Clostridium
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Gas Gangrene
Large doses of cephalosporin or penicillin Hyperbaric oxygen therapy No vaccines available Tetanus Common resident of soil and GI tracts of animals Causes tetanus or lockjaw, a neuromuscular disease Control infection with penicillin or tetracycline; and muscle relaxants Vaccine available; booster needed every 10 years Botulinum Rare but severe intoxication usually from home canned food Infectious botulism treated with penicillin |
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Gram-Positive Regular Non-Spore-Forming Bacilli
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Listeria monocytogenes
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Listeria monocytogenes
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Resistant to cold, heat, salt, pH extremes, and bile
Can contaminate foods and grow during refrigeration Listeriosis – most cases associated with dairy products, poultry, and meat |
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Gram-Positive Irregular Non-Spore-Forming Bacilli
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Corynebacterium
Mycobacterium Actinomyces Nocardia |
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Corynebacterium Diptheriae
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Causes diptheria
Reservoir of healthy carriers; potential for diphtheria is always present Most cases occur in non-immunized children living in crowded, unsanitary conditions Acquired via respiratory droplets from carriers or actively infected individuals Penicillin or erythromycin Prevented by toxoid vaccine series and boosters |
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Mycobacteria: Acid-Fast Bacilli
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Tuberculosis
5% to 10% of infected people develop clinical disease Untreated, the disease progresses slowly; majority of TB cases contained in lungs Clinical tuberculosis divided into: Primary tuberculosis Secondary tuberculosis (reactivation or reinfection) Disseminated (extrapulmonary) tuberculosis 6-24 months of at least 2 drugs from a list of 11 Vaccine based on attenuated bacilli Calmet-Guerin strain of M. bovis used in other countries |
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Mycobacterium Leprae: The Leprosy Bacillus
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Hansen’s bacillus/Hansen’s Disease
Mechanism of transmission is not fully verified 2 forms possible: Tuberculoid – asymmetrical, shallow lesions, damage nerves – results in local loss of pain reception Lepromatous – a deeply nodular infection that causes severe disfigurement of the face and extremities, widespread dissemination Treatment by long-term combined therapy WHO sponsoring a trial vaccine |
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Actinomycetes: Filamentous Bacilli
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May cause chronic infection of skin and soft tissues
Actinomyces israelii – responsible for diseases of the oral cavity, thoracic or intestines – actinomycoses Nocardia brasiliensis causes pulmonary disease similar to TB |
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Aerobic Gram-Negative Nonenteric Bacilli
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Pseudomonas
Burkholderia Acinetobacter baumanii Stenotrophomonas maltophilia Brucella (cattle and pigs) Francisella Tularensis Bordetella Pertussis Legionella Pneumophila |
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Pseudomonas Aeruginosa
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Resistant to soaps, dyes, quaternary ammonium disinfectants, drugs, drying
Frequent contaminant of ventilators, IV solutions, anesthesia equipment Opportunistic pathogen Common cause of nosocomial infections in hosts with burns, neoplastic disease, cystic fibrosis Complications include pneumonia, urinary tract infections (UTI), abscesses, otitis, and corneal disease Endocarditis, meningitis, bronchopneumonia Multidrug resistant |
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Burkholderia
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active in biodegradation
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Acinetobacter baumanii
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nosocomial and community acquired infections; wounds, lungs, urinary tract, burns, blood; extremely resistant – treatment with combination antimicrobials
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Stenotrophomonas maltophilia
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forms biofilms; contaminant of disinfectants dialysis equipment, respiratory equipment, water dispensers, and catheters; clinical isolate in respiratory soft tissue, blood, CSF; high resistance to multidrugs
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Brucella and Brucellosis
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Brucella abortus (cattle)
Brucella suis (pigs) Bang disease – a zoonosis transmitted to humans from infected animals Animal vaccine available Potential bioweapon |
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Francisella Tularensis and Tularemia
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Causes tularemia, a zoonotic disease of mammals endemic to the northern hemisphere, particularly rabbits
Attenuated vaccine Potential bioterrorism agent |
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Bordetella Pertussis
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Causes pertussis or whooping cough, a communicable childhood affliction
Vaccine |
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Legionella Pneumophila and Legionellosis
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Widely distributed in water
Legionnaires disease and Pontiac fever Prevalent in males over 50 Nosocomial disease in elderly patients Fever, cough, diarrhea, abdominal pain, pneumonia fatality rate of 3-30% |
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Enterobacteriaceae Family
The Enteric Bacteria |
Most frequent cause of diarrhea through enterotoxins
Enterics, along with Pseudomonas sp., account for almost 50% of nosocomial infections Facultative anaerobes, grow best in air |
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coliforms
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lactose fermenters
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non-coliforms
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non-lactose fermenters
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Enterobacteriaceae
Coliform Organisms |
E. coli
Klebsiella pneumoniae – normal inhabitant of respiratory tract, has large capsule, cause of nosocomial pneumonia, meningitis, bacteremia, wound infections, and UTIs Enterobacter sp. – UTIs, surgical wounds Citrobacter sp. – opportunistic UTIs and bacteremia Serratia marcescens – produces a red pigment; causes pneumonia, burn and wound infections, septicemia and meningitis |
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Enterobacteriaceae
Noncoliform Lactose-Negative Enterics |
Proteus, Morganella, Providencia – ordinarily harmless saprobes in soil, manure, sewage, polluted water, commensals of humans and animals
All demonstrate resistance to several antimicrobials Salmonella and Shigella not normal human flora Typhoid Fever - Salmonella typhi fecally contaminated food or water; 2 vaccines for temporary protection Shigella and Bacillary Dysentery Human parasites Human parasites |
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Escherichia Coli: The Most Prevalent Enteric Bacillus
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Most common aerobic and non-fastidious bacterium in gut
150 strains Some have developed virulence through plasmid transfer, others are opportunists Pathogenic strains frequent agents of infantile diarrhea – greatest cause of mortality among babies Causes ~70% of traveler’s diarrhea Causes 50-80% UTI |
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Nonenteric Yersinia Pestis and Plague
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Humans develop plague through contact with wild animals (sylvatic plague) or domestic or semidomestic animals (urban plague) or infected humans
Flea vectors – flea becomes ravenous Bubonic – bacillus multiplies in flea bite, enters lymph, causes necrosis and swelling called a bubo in groin or axilla Septicemic – progression to massive bacterial growth; virulence factors cause intravascular coagulation subcutaneous hemorrhage and purpura – black plague Pneumonic – infection localized to lungs, highly contagious; fatal without treatment Treatment: streptomycin, tetracycline, or chloramphenicol Killed or attenuated vaccine available |
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Oxidase-Positive Nonenteric Pathogens
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H. influenzae – acute bacterial meningitis, epiglottitis, otitis media, sinusitis, pneumonia, and bronchitis
Subunit vaccine Hib H. aegyptius – conjunctivitis, pink eye H. ducreyi – chancroid STD H. parainfluenzae and H. aphrophilus – normal oral and nasopharyngeal flora; infective endocarditis |
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The Spirochetes
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Genus Treponema
Syphilis Human is the natural host Extremely fastidious and sensitive; cannot survive long outside of the host Sexually transmitted and transplacental Leptospira and Leptospirosis causes leptospirosis, a zoonosis Borrelia : Arthropod-Borne Spirochetes transmitted by arthropod vector – relapsing fever – Lyme disease |
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Primary syphilis
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appearance of hard chancre at site of inoculation; chancre heals spontaneously
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Secondary syphilis
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fever, headache, sore throat, red or brown rash on skin, palms, and soles; rash disappears spontaneously
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Tertiary syphilis
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about 30% of infections enter in tertiary stage; can last for 20 years or longer; numerous pathologic complications occur in susceptible tissues and organs
Neural, cardiovascular symptoms, gummas develop |
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Congenital syphilis
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nasal discharge, skin eruptions, bone deformation, nervous system abnormalities
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Curviform Gram-Negative Bacteria and Enteric Diseases
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Vibrio – comma-shaped rods, single polar flagellum
Campylobacter – short spirals or curved rods; one flagellum Helicobacter – spirochete with tight spirals and several polar flagella |
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Vibrio Cholera
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Cholera toxin causes electrolyte and water loss through secretory diarrhea, “rice water stool”; resulting dehydration leads to muscle, circulatory, and neurological symptoms
Treatment: oral rehydration, tetracycline |
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Pathogens Carried by Seafood
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Salt-tolerant inhabitants of coastal waters, associate with marine invertebrates
Vibrio parahaemolyticus – gastroenteritis from raw seafood; symptoms similar to cholera Vibrio vulnificus – gastroenteritis from raw oysters; serious complications in persons with diabetes or liver disease Treatment – fluid and electrolyte replacement; occasionally antimicrobials |
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Campylobacter Vibrios
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Important cause of bacterial gastroenteritis
Campylobacter fetus – opportunistic pathogen that infects debilitated persons or women late in pregnancy Meningitis, pneumonia, arthritis, septicemia in the newborn |
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Helicobacter Pylori: Gastric Pathogen
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Causes 90% of stomach and duodenal ulcers; apparent cofactor in stomach cancer
People with type O blood have a 1.5-2X higher rate of ulcers |
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Rickettsiaceae
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Ticks, fleas, and lice are involved in their life cycle
Epidemic typhus – R. prowazekii carried by lice; starts with a high fever, chills, headache, rash; Brill-Zinsser is a chronic, recurrent form Endemic typhus – R. typhi, harbored by mice and rats; occurs sporadically in areas of high flea infestation; milder symptoms Rocky Mountain spotted fever – R. rickettsii zoonosis carried by dog and wood ticks; most cases in Southeast and on eastern seaboard; distinct spotted rash; may damage heart and CNS Ehrlichia genus contains 2 species of rickettsias; tick-borne bacteria cause human monocytic and granulocytic ehrlichiosis |
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Coxiella Burnetti
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Causes Q fever
Intracellular parasite Usually inhaled causing pneumonitis, fever, hepatitis |
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Bartonella Species
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Cause:
Trench fever, spread by lice Cat-scratch disease, a lymphatic infection associated with a clawing injury by cats Bacillary angiomatosus in AIDS patients |
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Chlamydiaceae
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Trachoma – attacks the mucous membranes of the eyes, genitourinary tract, and lungs
Ocular trachoma – severe infection, deforms eyelid and cornea, may cause blindness Inclusion conjunctivitis – occurs as baby passes through birth canal; prevented by prophylaxis STD – second most prevalent STD; urethritis, cervicitis, salpingitis (PID), infertility, scarring Lymphogranuloma venereum – disfiguring disease of the external genitalia and pelvic lymphatics |
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L forms or L-phase
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Exposure to certain drugs or enzymes can result in cell wall-deficient bacteria called L forms or
L-phase |
