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102 Cards in this Set

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  • Back
What conditions favor the growth of anaerobic bacteria?
Relative lack of oxygen - below 200 mV oxidation-reduction potential.
Why do some anaerobic bacteria have a degree of aerotolerance?
They have a very active NADH reductase which results in reduction of oxygen.
Most anaerobic infections are mixed or polymicrobial.
The correct answer is: True
What species of anaerobic bacteria are Gram-negative rods that do not form spores?
Bacteriodes.
Fusobacterium.
Prevotella.
Porphyromonas.
What anaerobic bacteria are Gram- negative cocci?
Veillonella
What anaerobic bacteria are associated with infections above the diaphragm?
Anaerobic oral flora - Peptostreptococcus, Prevotella, Fusobacterium
Anaerobic bacteria associated with infections below the diaphragm usually involve what species of bacteria?
The colonic flora - Bacteroides fragilis.
What anaerobic organism causes gangrene and food poisoning?
Clostridium perfringens.
What anaerobic bacterium causes fatal food poisoning?
Clostridium botulinum.
What anaerobic bacterium can cause a disease similar to myonecrosis in the gravid uterus with a resulting high mortality rate?
Clostridium perfringens.
Why is it important to discriminate between anaerobic cellulitis and myonecrosis caused by Clostridium perfringens?
Amputation or massive debridement are usually not required for cellulitis.
What anaerobic organism usually causes non-traumatic myonecrosis?
Clostridium septicum.
What anaerobic infection follows antibiotic therapy?
Clostridium difficile antibiotic-associated pseudomembranous colitis.
What infections are caused by Clostridium septicum?
Nontraumatic gangrene. Necrotizing enterocolitis.
Food poisoning due to Clostridium perfringens is a mild intoxication.
The correct answer is: True
Name the two toxins produced by Clostridium difficile and define their toxic action.
Toxin A - hemorrhagic, acts on epithelial cells of the gut.
Toxin B - lethal.
What is the treatment for Clostridium difficile pseudomembranous colitis?
Discontinue antimicrobics.
What product of Clostridium tetani is responsible for development of tetanus?
Solely due to the tetanus toxin.
Where are the spores of Clostridium tetani found?
Ubiquitous - in soil.
What is an important source of infection of infants with Clostridium botulinum?
Feeding honey.
What is the natural habitat of Pseudomonas spp.?
Moist environments - soil, water, plants
How are Pseudomonas infections usually transmitted?
Via water.
What are the Gram stain and morphological characteristics of Pseudomonas spp.?
Gram-negative rods.
Why is Pseudomonas infection a concern in the dental clinic?
The organism can be spread by aerosols generated by handpieces and contaminated water lines to handpieces.
What types of infections are caused by Pseudomonas aeruginosa?
Respiratory
Bacteremia
CNS infections
Ear infections
Eye infections
Bone and joint infections
Urinary tract infections
Gastrointestinal infections
Skin and soft tissue infections
How does algenate (the capsule) enhance the pathogenic potential of Pseudomonas?
Binding to tissues.
Anti-phagocytic.
Inhibits aminoglycoside antibiotics.
Besides its capsule what are some other virulence factors of Pseudomonas?
Pili.
Proteases. Cytotoxin. Hemolytic factors. Exotoxin A. Exotoxin S. Pyocyanin
What is typical of antimicrobic treatment of Pseudomonas and Burkholderia?
It must be aggressive, commonly using combinations of antibiotics that are synergistic.
What is the best way to prevent Pseudomonas and Burkholderia infections?
Rigorous cleanliness with attention paid to infection control practices.
What are the Gram staining and morphological characteristics of Neisseria?
Gram-negative diplococci (kidney bean shaped).
What types of growth requirements are needed by the pathogenic Neisseria spp.?
Enriched media needed.
What Neisseria species causes meningitis?
Neisseria meningitidis
In what age group do most of infections with Neisseria gonorrhoeae occur?
20 to 24 years of age.
In what age group does most of meningitis due to Neisseria meningitidis occur?
Children - 6 months to 4 years.
A second peak occurs at 18 years of age.
What are the most severe consequences of Neisseria meningitidis?
A high case fatality ratio in the USA. An epidemic killer in developing countries.
Why is an understanding of Neisseria infections important to the dentist?
These organisms can infect oropharyngeal mucosal surfaces. Proper practices are needed to protect the dentist and patient.
What are the risks of production of aerosols containing Neisseria to the dentist?
Infection of the conjunctiva leading to severe conjunctivitis, corneal ulceration, abscesses and potentially blindness.
What types of infections can occur due to Neisseria gonorrhoeae?
Uncomplicated genital mucosal infection.
Pharynx infection.
Ophthalmia neonatorum - due to contamination at birth.
Are complications due to Neisseria gonorrhoeae common in the male?
No.
What are the complications associated with Neisseria gonorrhoeae in the female?
Disseminated gonococcal infection
Pelvic inflammatory disease
Endocervical gonorrhea.
What part of the Neisseria gonorrhoeae organism is responsible for producing inflammation?
Endotoxin.
Peptidoglycan fragments.
How does Neisseria gonorrhoeae avoid the immune system?
lgA1 protease
Molecular mimicry - similarity to human antigens makes this organism have weak antigens.
Serum resistance - resistant to killing effects of complement.
Blocking antibody - these don't bind complement.
Phase and antigen variation.
How is Neisseria meningitidis spread?
Aerosols.
What types of infection are caused by Neisseria meningitidis?
Bacteremia.
Meningitis.
Meningoencephalitis.
Why is Neisseria meningitidis infection so dangerous?
Can be fulminant with death occurring as soon as 12 hours after appearance of symptoms.
What are the virulence traits of Neisseria meningitidis?
Endotoxin (LOS).
Peptidoglycan fragments.
lgA1 protease.
Anti-phagocytic capsule.
Phase variation.
Molecular mimicry.
Does effective immunity develop subsequent to infection with Neisseria meningitidis?
Yes. Due to development of cross¬reactive antibodies with normal flora.
What age group is most susceptible to Neisseria meningitidis infection?
6 months to 4 years old.
What can be done to prevent Neisseria meningitidis infection?
Vaccine - not effective in young children.
Contact tracing.
Isolate infected patients.
What is the normal habitat of nonpathogenic Neisseria species?
Mucus membranes of the throat and vagina.
What is different about the growth requirements of pathogenic versus nonpathogenic Neisseria?
Pathogens require chocolate agar and 5% C02.
Non-pathogens grow on simple nutrient agars in ambient air.
What is the etiologic agent of tetanus?
Clostridium tetani.
What is the mechanism of action of the tetanus toxin?
Causes spastic paralysis. Inhibits the release of inhibitory neurotransmitters.
What is the treatment for tetanus?
Administration of anti-toxin.
What sites in the body favor the growth of anaerobes?
The gastrointestinal tract. Abscesses.
Why is oxygen toxic to most anaerobes?
Most anaerobes lack a superoxide dismutase to eliminate oxygen radicals.
What species of anaerobes are Gram- positive rods that produce spores?
Clostridium species.
What anaerobes are Gram-positive cocci?
Peptostreptococcus
What is the source of infections with anaerobes that do not form spores?
Most exist as commensals - i.e. normal flora of man and animals. Their source is endogenous.
In what part of the gut are bile resistant anaerobes found?
In the colon, mostly Bacteroides.
Where are the bile sensitive anaerobes found?
In the upper Gl tract and oropharynx - Prevotella mostly.
Do infections with Clostridia come from an endogenous or exogenous source?
Exogenous. Most of these organisms are found in soil and water.
What are the predisposing factors that contribute to development of Clostridial pseudomembranous colitis?
Age - elderly more susceptible. Females.
Impaired intestinal motility.
What organism causes gas gangrene?
Clostridium perfringens.
What is the cause of antibiotic associated pseudomembranous colitis?
Clostridium difficile.
What is the etiologic agent of gonorrhea?
Neisseria gonorrhoeae
What infection of children is considered to be an indication of child abuse?
Neisseria gonorrhoeae
What is gas gangrene?
Necrosis limited to muscle tissue.
What symptoms are associated with gas gangrene?
Toxemia and shock.
Extensive edema.
Massive tissue damage.
Variable amounts of gas.
What anaerobe produces abscesses in liver?
Fusobacterium necrophorum
Prevotella.
Porphyromonas.
What anaerobe is isolated from most cases of peritonitis and peritoneal abscess?
Bacteroides fragilis.
What is the most common source of botulism?
Canned foods. Especially home canning.
Is botulism an infection or an intoxication?
Intoxication.
What type of botulism requires growth of the organism in the human host?
Infant botulism - it grows in the intestinal tract.
What are the three phases of symptoms for botulism?
Early: weakness, lassitude, dizziness - ie not unique to this disease.
Intermediate: Diplopia, Dysphonia, Dysphagia, Pupils dilated, tongue dry
Late: weakness of neck, proximal extremities and respiratory muscles - death
What is the treatment for botulism?
Antitoxin and physiological support.
What type of paralysis is caused by the botulinum toxin?
A flaccid paralysis.
How do you diagnose N. gonorrhoeae infection?
Culture is most reliable.
Antibiotic resistance is common among strains of N. gonorrhoeae.
The correct answer is: True
How do you prevent infection with N. gonorrhoeae?
Abstinence.
Use of condoms
Tracking contacts.
What are the Gram staining and morphological characteristics of Haemophilus species?
Gram-negative pleomorphic rods
What special growth requirements are needed by Haemophilus species?
X factor - heme V factor - NAD or NADP
What diseases are caused by Haemophilus influenzae?
Meningitis. Otitis media.
What diseases are caused by Haemophilus parainfluenzae?
Endocarditis
Where is Haemophilus aphrophilus found in the body?
In the oral cavity.
What diseases can Haemophilus aphrophilus cause?
Colonizer of dental plaque. Juvenile forms of periodontitis. Endocarditis.
Brain abscesses.
Spinal fluid infections.
Jaw infections.
Wound infections.
Where is Haemophilus paraphrophilus found?
Colonizes dental plaque and other sites.
What diseases can be caused by Haemophilus paraphrophilus?
Endocarditis. Brain abscess. Osteomyelitis.
What are the major consequences to patients due to colonization of the oral cavity with Haemophilus species?
Juvenile forms of periodontal disease. Dental procedures leading to endocarditis.
What is the most common infection due to Haemophilus influenzae?
Meningitis.
Which type of Haemophilus influenza causes most invasive disease?
Type b
What type of Haemophilus influenzae commonly causes otitis media?
Nonencapsulated, nontypeable H. influenzae
Does immunity develop after infection with N. gonorrhoeae?
No.
What percent of women will develop gonorrhea after one sexual encounter with an infected male?
50%
What percent of men will develop gonorrhea after one sexual encounter with an infected female?
20%
What accounts for the increase in the number of gonorrhea cases in recent years?
An increase in antibiotic resistant strains.
Asymptomatic carriers.
Short-term immunity.
Changes in sexual habits of society.
What are the virulence traits of N. gonorrhoeae?
Pili for adherence.
Capsule - anti-phagocytic.
IgA protease.
Lipooligosaccharide (LOS) - like endotoxin.
Iron acquisition systems.
Name five types of infections caused by N. gonorrhoeae.
Urethritis.
Cervicitis or vaginitis.
Salpingitis.
Pelvic inflammatory disease (PID). Ophthalmia neonatorum.
What are the diagnostic features of N. gonorrhoeae in the male?
Detection of Gram-negative, intracellular diplococci in the urethral discharge.
What must be done to diagnose N. gonorrhoeae in the female?
Culture and identification of the organism.
Besides infection of the urethra or vagina, what other types of lesions can be seen in patients infected with N. gonorrhoeae?
Pharyngitis.
Anal-rectal infection.
Skin lesions.
Disseminated infection.
Septic arthritis.
If a patient with N. gonorrhoeae does not respond to antibiotic therapy, what is the most likely reason?
Co-infection with Chlamydia trachomatis.