Anaerobes
description
Transcript of Anaerobes
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Clinical Treatment
Specimen transport and processing
Positive Bacilli
Anaerobic cocci
Negative Bacilli
Environmental
Conditions
Anaerobes
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Obligate Anaerobes only grow in the absence of oxygen (O2)
Aerotolerant / Microaerophilic anaerobes grow in reduced concentration of oxygen (~5% O2), but grow best under strict anaerobic
conditions
Environmental Conditions
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Peptostreptococcus
Vieonella??? Get correct spelling
Anaerobic cocci
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Peptostreptococcus
(Peptoniphilus) spp.
Intestinal gram positive cocci
Key reactions • Nitrate (+)• SPS –sensitive • Indole (-)
P. assacharolyticusForm tetrads or pairs
Key reactions : SPS resistant, Indole
(+), Nitrate (-)
P. anaerobius• Elongated
• Produce sweet odor due to the presence of isocaproic acid
Causes:
•Head, neck , genital and gut infections
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Viellonella species
Key reactions •Nitrate (+)
• Non-fluorescent, may pigment red
Causes :
Endocarditis and bacteremia
Indigenous to oral cavity, upper respiratory, G.I and genitourinary tract
Kanamycin (S )Vancomycin (R )Colistin (S) Small
Gram negative cocci
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Clostridium species
Others ?????
Positive Bacilli
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Clostridium spp.
Gram positive rods
Causes :• Food poisoning•Gas gangrene(myonecrosis) •Neoplasm s•Lock jaw•Pseudomembraneous colitis
Spore formersFound
commonly in stool specimen
Produce Virulence factors that are responsible for
infections
Four common species• Clostridium perfringens• Clostridium difficile• Clostridium tetani• Clostridium botulism• Other Clostridium
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Appearance: box-shaped gram positive rod
Two zone beta hemolytic on SBA Produces alpha and Theta toxin
Key reactions: Lecthinase (+), nitrate (+) Reverse camp with group B Strep. Stormy fermentation of litmus milk Kanamycin (S ), Vancomycin (S), Colistin (R)
Causes: Gas gangrene, Food poisoning (Enterotoxin A), Soft tissue
infections in diabetics and Necrotizing bowel disease
Clostridium perfringens
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Subterminal spore
Chartreuse fluorescence
Key reactions Ferment fructose Lecthinase (-), Lipase (-)
Causes:Pseudomonas colitis and Antibiotic associated
diarrhea (AAD) due to enterotoxin A and B
Clostridium difficile
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Toxin: tetanospasmin (neurotoxic exotoxin)
Motile, swarms Appearance: Gram positive rods. Produce terminal spores that appear as drumsticks
Biochemical reactions:Lipase (-), Indole (+)
Causes:Lockjaw, respiratory failure and tetanus neonatorum
Clostridium tetani
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Toxin: botulin
Key reaction: Lipase (+)
Causes:Botulism: Inhibits acetlycholine release from motor
neurons
Clostridium botulism
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Clostridium novyiBeta hemolytic
Key reactions:Lecithinase (+),
lipase (+), indole (-), urease (-)
Causes: Gas gangrene (myonecrosis)
and toxic shock
Rapid swarmerCharacteristic: medusa head, subterminal spores
Key reactions:Lipase (-), Indole (-)
Causes:Neoplasm of the colon, breast leukemia, lymphoma, enterocolitis. myonecrosis
Other Clostridium spp.Clostridium septicum
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Lactobacillus
Gram positive Non-spore forming bacilli
Normal flora in the oral cavity,
G.I. and female genital
tract
•Protect female genital tract
• Produce lactic acid to lower vaginal pH
Infections caused:Bacterial vaginosis
Pelvic inflammatory disease
Key reactions • Catalase (-)•Cephalosporin (R)•Vancomycin (R )
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Proprionibacteriumacnes
Gram positive Non-spore forming bacilli
(appear as diptheroids)
Normal flora of the skin
Can cause:Subacute bacterial
endocarditis
Bacteremia
Reactions • Catalase (+)•Indole (+)•Nitrate (+ )
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Bacteroides fragilis
Bacteroides ureolyticus
Fusobacterium nucleatum
Fusobacterium necrophorum
Other Fusobacterium
Porphyromona spp.
Prevotella spp.
Negative Bacilli
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Bacteroides fragilis
Key reactions •Catalase (+)
•Indole (-)
•Nitrate (-)
Bile tolerant, Non-motile
Causes :• Inflammation of the intestinal wall• Septic abortion• Thrombosis •G.I. infections
Gram negative rod
Penicillin (R )Kanamycin (R )Vancomycin (R )Colistin (R )Clindamycin (S)
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Bacteroides ureolyticus
Key reaction
• Urease (+)
Bile sensitive, Non-motile
Causes :• Respiratory infections•Intestinal tract infections
Gram negative rod
Kanamycin (S )Vancomycin (R )Colistin (S)
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Fusobacterium nucleatum
Key reactions • Lipase (-)
• Indole (+)
Causes :
Metastatic brain abscess
Fusiform Gram negative
bacilli
Kanamycin (S )
Vancomycin (R )
Colistin (S)
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Fusobacterium
necrophorum
Key reaction
• Lipase (+)
Causes :
Pertonsillar abscess in children and
young adult
Pleomorphic filamentous
gram negative rod
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Prevotella melaninogenic
a Gram negative
coccobacilli
• Produces foul odor
• Slow producer of protoporphin
Causes :
Lung and dental infections
Normal flora in the oral, G.I and
vaginal area
Kanamycin (R )Vancomycin (R )Colistin (S)Penicillin (R)
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Acceptable specimens : Aspirates from sterile site deep wounds , bodily fluids (except urine, sputum and saliva), and suprapubic
bladder aspirates
Primary media: Brucella (CDC or Schaedler) blood agar- contains hemin, vitamin K and yeast extract. Detect hemolysis in anaerobes
Special media: Bacteroides bile esculin (BBE) agar- contains gentamycin (inhibits facultative aerobic gram negative rods ) and 20% bile.
Laked Kanamycin Vancomycin (LKV) blood agar – identify pigmented gram negatives . (Kanamycin inhibits facultative gram negative rods and Vancomycin inhibits gram positive rods)
Phenyl-ethyl Alcohol (PEA) plate : inhibits swarming
Cycloserine cefoxitin fructose (CCFA) agar: selective for Clostridium difficile
Egg yolk agar- selective for Lecithinase and lipase production
Thioglycollate broth: provides reduced O2 environment
Specimen transport and processing
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Identification tests :Catalase test: distinguish aerotolerant anaerobes from anaerobic
organisms Indole: identify organisms that produce tryptophanase (Note: media needs
to contain tryptophan) Nitrate test:Urea test: identify organisms that produce urease. Observe pH change.
Urea is converted to ammonia
Incubate media in anaerobic gas chambers Contains H2, N2, carbon dioxide , palladium catalyst and desiccants
(absorb water) Keep media for 7 days
Specimen transport and processing
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Metronidazole – best treatment. Confirms the presence of an anaerobe
Clostridium infection: Use antitoxins , antibiotics (i.e. Chloramphenicol, pipercillin,
imipramine or ampicillin/sulbactam) and supportive therapy
Clinical Treatment