-
Where are Anaerobic cocci generally found?
Normal flora of the intestines, female genital tract, oral cavity, and respiratory tract
-
What clinical conditions are associated with Anaerobic cocci?
- Polymicrobial liver and brain abscesses
- Wound infections
-
What species has the tests and results:
Catalase POS
Produces olive-green colonies that become black
Peptococcus niger
-
What are the species names of Peptostreptococcus?
- P. anaerobius
- Finegoldia magna
- Peptoniphilus asaccharolytica
-
What bacteria is IDed with the test:
Inhibited by sodium polyanethol sulfonate (SPS)
Peptostreptococcus anaerobius
-
What species has the tests and results:
Small, gram-negative cocci
Reduces nitrate to nitrite
Does not ferment any carbohydrates
Sensitive to kanamycin and colistin
Resistant to vancomycin
Veillonella
-
What species in general has the identifying characteristics:
Clinical conditions: Abdomen infections, Chest infections, Pelvic actinomycosis in women with intrauterine devices (most common)
Exudate contains sulfur granules - dense clumps of bacteria
Gram Positive bacilli with beaded appearance, often filamentous (Branching gram positive bacilli)
Colony morphology - smooth to molar toothlike morphology
Actinomyces
-
What species are included in Propionibacterium?
- Propionibacterium acnes
- Propionibacterium propionicus
-
What are species are often called anaerobic diphtheroids?
Propionibacterium
-
What species has the tests and results:
Catalase POS
Indole POS
Usually Normal flora of the skin, mouth, and GI tract, Rarely pathogenic
Propionibacterium
-
What species has the tests and results:
Clinical conditions: BV (Bacterial vaginosis), PID (Pelvic inflammatory disease), Abdominal infections
Curved bacilli
Motile
Catalase NEG
Indole NEG
Inhibited by vancomycin
Mobiluncus
-
Is Lactobacillus pathogenic or normal flora?
- Normal flora of the GI and female gential tract
- Organism helps maintain and acidic environment in the vagina
- If the population of lactobacilli decreases, the risk of BV (bacterial vaginosis) increases
- Rarely pathogenic
-
What species has the tests and results:
Clinical conditions: If the population of this organism decreases, the risk of BV (bacterial vaginosis) increases but rarely pathogenic
Catalase NEG
Nonmotile bacilli
Generally aerotolerant anaerobes and will form small alph-hemolytic on SBA
Lactobacillus
-
What are some other nonpathogenic normal oral and intestinal flora?
- Bifidobacterium
- Eubacterium
-
Are most Clostridium species motile or nonmotile?
- Motile
- Except C. perfringens, C. ramosum, and C. inocuum
-
What patients are more prone to infections with Clostridium perfringens?
- Diabetics
- Patients with circulatory disorders
-
What does Clostridium perfringens secrete?
Enzymes and exotoxins that cause severe tissue damage
-
How is the Clostridium perfringens divided?
- 5 different types
- A-E
- Based on the quantities and types of exotoxins produced
-
What bacteria has the tests and results:
Clinical conditions: Gas Gangrene (myonecrosis), Post-abortion sepsisAbdominal infections, Enterocolitis, Food poisoning (mild-moderate diarrhea)
Produces a double zone of beta-hemolysis on SBA when incubated anaerobically
Exhibits a positive (enhanced hemolysis) reverse CAMP test (Strep agalactiae - Group B - is substituted for Staph aureus in the standard CAMP test)
Lecithinase POS
Glucose, Lactose, maltose, and fructose POS
Spores subterminal but difficult to induce
Nonmotile
Nagler test - prevents the opaque zone from forming - not performed much today
Clostridium perfringens
-
How is Clostridium tetani treated and prevented?
Antitoxin and vaccine (DPT: diptheria, pertussis, and tetanus trivalent vaccine) booster every 5 years
-
What bacteria has the tests and results:
Clinical condition: Tatanospasmin, Neurotoxin that affects the anterior horn cells of the spinal cord, resulting in involuntary muscle contractions, Contractions begin with the neck and jaw (lock jaw) and progress to a backward arching of the back muscles
Gram positive bacilli with round/terminal spores that resembles drumsticks
Gelatinase POS
Indole POS
Motile
Lecinthinase NEG
Lipase NEG
Generally not cultured
Diagnosis made by signs, symptoms, and toxin detection
Clostridium tetani
-
What does Clostridium botulinum produce?
Botulism toxin
-
What bacteria has the tests and results:
Clinical conditions: Botulism, Infant botulism, Neurotoxin binds to the synapse of nerve fibers, resulting in acute (flaccid) paralysis and death
Lipase POS
Lecithinase POS
Glucose POS
Motile
Spores are oval, subterminal and resemble tennis rackets
Clostridium botulinum
-
What does Clostridium difficile produce?
Enterotoxin A and/or cytotoxin B
-
How is Clostridium difficile diagnosed?
Detecting toxin in the stool
-
What bacteria has the tests and results:
Clinical condition: Antibiotic associated pseudomembranous colitis and Diarrhea
Cultures should only be perfomed on watery or unformed stools
Cycloserin-cefoxitin-fructose agar (CCFA) is used to isolate C. difficile
Weakly fructose POS
In anaerobic conditions, the pH indicator will turn yellow at 5.3
Fluoresce yellow-green
Lecinthinase NEG
Lipase NEG
Indole NEG
Motile
Glucose and fructose POS
Spores are oval and subterminal
Clostridium difficile
-
What clinical conditions are associated with Clostridium septicum?
Occasionally linked to gas gangrene
-
Describe the most common anaerobe responsible for anaerobic infections and why it is resistant
- Bacteroides fragilis group
- A polysaccharide capsule is an important virulence mechanism
-
What bacteria the tests and results:
Nonmotile gram negative bacilli with rounded ends and may be pleomorphic
Nonhemolytic on anaerobic blood agar
Growth in 20% bile
Catalase POS
Lipase NEG
Bile esculin POS
Lecithinase NEG
Gelatinase NEG
Produces brown to black colonies on BBE agar
Resistant to penicillin, kanamycin, vancomycin
Susceptible to rifampin
Bacteroides fragilis group
-
What bacteria the tests and results:
Clinical conditions: Head, neck, and lower respiratory tract infections
Pigmented
Saccarolytic
Gram negative bacilli
Young colonies appear tan and exhibit brick-red fluorescence under ultraviolet (UV) light
Older colonies are brown to black (may take up to 3 weeks to see brown to black pigment)
Ferments glucose and many other carbs
Inhibited by 20% bile
Susceptible to rifampin
Resistant to kanamycin
Prevotella melaninogenica
-
What bacteria has the tests and results:
Clinical conditions: Head, neck, oral cavity, and urogenital tract infections
Asaccharolytic or weak fermenters
Pigmented colonies
Gram negative colonies
Brick red fluorescence under UV light
Will NOT grow on KVLB
Inhibited by bile
Sensitive by Vancomycin, penicillin, and rifampin
Resistant to kanamycin
Porphyromonas
-
What bacteria is identified by:
Clinical conditions: Infections of pulmonary, blood, sinus, and dental cavity, Brain abcesses, Many infections are associated with metastatic conditions
Asaccharolytic or weak fermenters
Nonpigmented colonies
Long, thin, filamentous gram negative bacilli with tapered ends arranged end-to-end
Colony morphology - opalescent with speckles
Indole POS
Lipase POS
Nitrate NEG
Catalase NEG
Relatively biochemically inactive
Sensitive to kanamycin and colistin
Resistant to Vancomycin
Fusobacterium
-
What are the 2 important species of Fusobacterium?
- Fusobacterium nucleatum
- Fusobacterium necrophorum
-
What are the clinical conditions associated with Fusobacterium nucleatum?
- Serious pulmonary infections
- More common isolate
-
What clinical conditions are associated with Fusobacterium necrophorum?
- Lung abcesses
- Liver abcesses
- Arthritis
- Causes serious infections
-
What is the gram stain morphology of Bacteroides and Prevotella?
Pale, pleomorphic gram negative coccobacilli with bipolar staining
-
What is the gram stain morphology of Clostridium?
- Larg gram positive bacilli
- Spore location (terminal, central, or subterminal) is important in species identification
-
What are the most important biochemical tests performed on anaerobes?
- Catalase
- Nitrate
- Urease
- Indole
- Antimicrobial susceptibility disks can also be used to identify anaerobes
-
What nutrient is needed to enhance the growth of Prevotella and Porphyromonas?
Vitamin K
-
What nutrient is needed to enhance the growth of Bacteroides and Prevotella?
Hemin
-
What media is used for general growth of all anaerobes?
CDC (Centers for Disease Control and Prevention anerobic blood agar)
-
What media is selective and differential used to culture and presumpitvely identify Bacteroides fragilis?
BBE (Bacteroides bile esculin agar)
-
What media is an enriched selective medium for isolation of slowly growing anaerobes such as Prevotella and Bacteroides?
- KVLB (Kanamycin-vancomycin lakes sheep blood agar)
- Laked blood enhances pigment formation
-
What media is enriched and selective used to grow most anaerobes, including Clostridium and Bacteroides, also inhibits the growth of facultative, anerobic gram-negative bacilli (like Enterobacteriaceae)?
PEA (Penylethyl alcohol agar)
-
What media inhibits gram-negative organisms and is used to grow most gram-positive anaerobes and facultative anerobes?
Columbia-colistin-naladixic agar with 5% sheep blood
-
What media is used to detect proteolytic enzymes (lipase and lecithinase) produced by Clostridium?
Egg yolk agar
-
What does Lecithinase activity on egg yolk agar look like?
Produces and opaque zone from the cleavage of lecithin releasing insoluble fats (diglyceride)
-
What broths with reducing agents can be used to grow anerobic bacteria?
- Thioglycolate and cooked (or chopped) meat
- Resazurin can be added as an oxidation-reduction indicator
-
When resazurin is added to thioglycolate as an indicator, how does it look and what does it indicate?
- Pink in the presence of oxygen
- Colorless when reduced
-
What are commonly used systems to place solid media in anaerobic conditions for obligate anaerobes to grow?
- Anaerobic GasPak jars and bags
- Anaerobic hoods
-
What are the indicators used to ensure the anaerobic conditions have been met, in anaerobic GasPak jars and bags?
- Pallidium causes the following reaction:
- 2H2 + O2 > 2H2O2
- Methylene blue is the most commonly used oxidation-reduction indicator that will turn from blue to white, indicating reduction
-
What test must be performed before attempting to identify a possible anaerobe?
Aerotolerance test
-
Describe the Aerotolerance test
- Colony is inoculated to an anerobic blood agar plate (incubated aerobically) and to a chocolate agar plate (incubated with increased CO2)
- Isolates growing only on the plate incubated anaerobically are obligate anaerobes
-
When would you suspect anaerobic bacteria in an infection?
- Foul odor (from gas production)
- Necrotic tissue
- Anaerobic body sites, wounds, abcesses
- Surgical specimens
-
Define and obligate anaerobe
Bacterium that cannot use oxygen for metabolism and oxygen is lethal to the microorganism
-
Define aerotolerant anaerobe
Bacterium that cannot use oxygen but can grow in its presence
-
Define facultative anaerobe
Bacterium that will use oxygen if it is present and can grow, albeit more slowly without oxygen
-
Define obligate anaerobe
Bacterium that requires oxygen at concentrations found in room air, about 20%
-
Define microaerophile
Bacterium that requires oxygen at concentrations of 5-10%
-
Define Capnophile
Bacterium that requires increased concentration of CO2
|
|