Term
| What are some parts of the human body where anaerobes are a major part of the normal flora? |
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Definition
| colon, mouth, throat, upper GI, genital tract, skin |
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Term
| What are aerobic bacteria that prefer air but can grow without it called? |
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Definition
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Term
| What are anaerobic bacteria that can grow in up to 5% oxygen called? |
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Definition
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Term
| What conditions can devitalize tissues so that they allow opportunistic infections by anaerobes? |
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Definition
- trauma
- malignancy
- inflammation
- impaired blood supply
- surgery
- foreign body
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Term
| What sort of specimens are acceptable for culturing anaerobic bacteria? |
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Definition
abscess fluid aspirates
surgically removed tissue
blood cultures
sputum that bypass normal oral flora |
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Term
| What are some unacceptable speciemsn for anaerobic culture? |
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Definition
- cough sputum
- bronchoscopy specimens that reveal squamous epithelial cells
- superficially collected specimens from skin and wounds
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Term
| What are some special specimen transport devices tha are used to keep anaerobes alive? |
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Definition
- "gassed-out" tubes (oxygen-free tubes with a rubber top seal)
- anaerobic gel for swabs
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Term
| What are acceptable transport times for anaerobes with and without special transport devices? |
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Definition
with: 8-48 hrs
without: only 30-120 min |
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Term
| What special enriched growth media do anaerobic cultures need and how long do they need to be incubated to reach stationary phase? |
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Definition
- extra rich agar base + 0.1% glucose
- vitamin K
- hemin
- yeast extract
- cysteine (reducing agent)
- need to incubate for 48 hrs
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Term
| What are two characteristics of Clostridium perfringens that make a culture easy to identify? |
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Definition
- double zone of hemolysis of blood agar
- litmus milk medium produces "stormy fermentation"
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Term
| What are three toxins produced by Clostridium perfringens and which is the main pathogenic factor? |
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Definition
- alpha toxin - main pathogenic factor
- theta toxin - toxic for heart muscle and capillaries
- enterotoxin - causes food poisoning
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Term
| Which Clostridium perfringens toxin is similar to Streptolysin O produced by Strep. pyogenes? |
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Definition
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Term
| What is the clinical consequence of a severe traumatic wound infected with Clostridium perfringens and how is it treated? |
|
Definition
gas gangrene:
- surgical debridement
- draining the wound
- hyperbaric oxygen chamber
- penicillin
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Term
| What is the primary way to diagnose gas gangrene? |
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Definition
| clinical diagnosis: detect gas in infected tissues (palpitation for crepitation, x-ray) |
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Term
| What results from Clostridium perfringens infection of products of conceptions retained in the uterus? |
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Definition
| endometriosis: rapid necrosis and intravascular hemolysis from alpha and theta toxins spreads to uterus and surrounding area |
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Term
| How soon after eating Clostridium perfringens-contaminated food will symptoms appear? What are the symptoms? |
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Definition
| 8-24 hours - nausea, abdominal pain, diarrhea (no vomiting) |
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Term
| In Clostridium perfringens food poisoning, about how many organisms could be found and cultured from 1 gram of food? |
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Definition
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Term
| Where are Clostridium tetani spores typically found? |
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Definition
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Term
| What do Clostridium tetani cultures look like? |
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Definition
| a "drumstick": slim Gram-positive rod with a spore on the terminal end |
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Term
| What does Clostridium tetani produce to cause tetanus and how much of it is needed? |
|
Definition
tetanospasmin, a neurotoxic exotoxin that is produced at the site of the wound, travels to the CNS and blocks postsynaptic inhibition of spinal motor reflexes (resulting in spasmodic contractions)
- only 1 microgram is lethal to humans |
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Term
| What is a predisposing factor for Clostridium tetani infection? |
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Definition
| puncture wound (i.e. splinter or nail) or massive traumatic wound (very anaerobic conditions) |
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Term
| How long is the incubation period for Clostridium tetani? |
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Definition
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Term
| What are the clinical manifestations of Clostridium tetani? |
|
Definition
- masseter muscles (first affected) => lockjaw
- other muscles => affect respiration and swallowing
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Term
| What is the rate of mortality for untreated Clostridium tetani? |
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Definition
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Term
| How are people immunized against tetanus? |
|
Definition
the tetanospasmin toxin is treated with formalin and given as part of a DPT shot to children at ages 2, 4, 6, and 18 months, then boosters at age 6 and every 10 yrs afterwards
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Term
| How does Clostridium botulinum neurotoxin work? |
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Definition
| 7 antigenically distinct toxins (A-G), inhibit acetylcholine release and cause muscular paralysis |
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Term
| What is the lethal dose for Clostridium botulinum neurotoxin and how can it be inactivated? |
|
Definition
| < 1ug; inactivated by boiling 10 min; (acidic foods may retard germination) |
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Term
| What are the clinical manifestations of Clostridium botulinum infection? |
|
Definition
- dry mouth, difficulty swallowing
- double/blurred vision
- difficulty walking and keeping balance
- difficulty breathing
- paralysis
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Term
| What is the typical incubation period for food botulism cases? |
|
Definition
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|
Term
| What is the mortality rate for Clostridium botulinum, and how is it treated? |
|
Definition
10% or less with intensive care
treatment is ventilatory support and multivalent antitoxin |
|
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Term
| What causes flopyy baby syndrome and up to what age can they be affected? |
|
Definition
| Clostridium botulinum infection of infant colon via introduction of solid foods or honey; occurs up to 8 months of age |
|
|
Term
| What the symptoms of infant botulism? |
|
Definition
| constipation, poor muscle tone, lethargy and feeding problems |
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|
Term
| How does wound botulism occur? |
|
Definition
| Clostridium botulinum grows in a wound and produces neurotoxin; seen in cocaine users |
|
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Term
| What are some side effects of Botox? |
|
Definition
- toxin may spread to other areas of the body and cause symptoms similar to botulism
- in children with cerebral palsy: life-threatening if swallowed
- chronic infection at injection sites
- droopy eye lids
- vertical misalignment of the eye
- difficulty swallowing and dry mouth
- vision or speech problems
- weakness, pain
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Term
| What percent of the intestinal flora of adults is made up of clostridium difficile? |
|
Definition
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Term
| What are the toxins that clostridium difficile produces? |
|
Definition
- toxin A: enterotoxin for entry into cell
- toxin B: most potent cytotoxin
- binary toxin: in some strains, causes increased virulence
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Term
| clostridium difficile produces nosocomial gut infection in ____% of all hospitalized patients? |
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Definition
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|
Term
| How does clostridium difficile cause diarrhea? |
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Definition
| it is a side-effect of antibiotic treatment (remove normal flora and allow overgrowth of C. difficile) |
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Term
| How does clostridium difficile cause pseudomembrane colitis? |
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Definition
| toxin production produces a "pseudomembrane" of fibrin and cells in the colon, which can progress to severe gut inflammation |
|
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Term
| How is pseudomembrane colitis treated? |
|
Definition
- stop the offending antibiotic
- treat with vancomycin or metronidazole
- may need surgery to remove part of the colon
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Term
| What are some measures taken to prevent clostridium difficile infection? |
|
Definition
- early diagnosis
- isolate patients to prevent spread of spores
- clean hospital rooms with Clorox
- wash hands with soap and water
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Term
| What are two non-spore-forming Gram-positive anaerobic rods that are pathogenic, and two that are non-pathogenic? |
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Definition
| Actinomyces and propionibacterium are more pathogenic, lactobacillus and eubacterium are less pathogenic |
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Term
| Are Actinomyces acid-fast or non-acid fast? Aerobic or anaerobic? |
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Definition
|
|
Term
| What is the appearance of Actinomyces israelii colonies? |
|
Definition
anaerobic, non-acid-fast, Gram-positive rods
irregular, small white fuzzy colonies: "molar tooth" |
|
|
Term
| What diseases are Actinomyces associated with? |
|
Definition
- Abscess formation in the female genital tract if IUDs are left in the uterus too long
- aspiration pneumonia
- abscesses in neck or head
- chronic draining wound infections in the mouth and throat (i.e. after oral surgery)
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Term
| What are "sulphur granules"? |
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Definition
| colonies of Actinomyces found in pus draining from infections, resemble bread crumbs |
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Term
| What is the most common anaerobic Gram-negative rod that causes abdominal infections? |
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Definition
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|
Term
| What kind of agar do Bacteroides fragilis grow best on? |
|
Definition
| bile esculin selective agar (20% bile) |
|
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Term
| Why is Bacteroides fragilis resistant to penicillin and to phagocytosis? |
|
Definition
| beta-lactamase positive; has a capsule with antiphagocytic function |
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Term
| What are the characteristics of Fusobacterium? |
|
Definition
- spindle-shaped
- Gram-negative rod
- slow-growing
- sensitive to penicillin
|
|
|
Term
| What is the most common species of the Fusobacterium genus? |
|
Definition
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|
Term
| What are the differences between Fusobacterium and Bacteroides fragilis? |
|
Definition
Fusobacteria are:
- less virulent
- less common
- more difficult to grow (more sensitive to O2)
- more sensitive to penicillin G
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|
|
Term
| What are some anaerobic susceptibility tests? |
|
Definition
- beta-lactamase test: determine whether the organism is resistant to Penicillin G
- MIC testing: only acceptable way to do a complete susceptibility test panel
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