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