Clinical Treatment

Specimen transport and processing

Positive Bacilli

Anaerobic cocci

Negative Bacilli

Environmental Conditions

Anaerobes

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

Peptostreptococcus

Vieonella??? Get correct spelling

Anaerobic cocci

Peptostreptococcus

(Peptoniphilus) spp.

Intestinal gram positive cocci

Key reactions • Nitrate (+)• SPS –sensitive • Indole (-)

P. assacharolyticus

Form tetrads or pairsKey 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

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

Clostridium species

Others ?????

Positive Bacilli

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

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 milkKanamycin (S ), Vancomycin (S), Colistin (R)

Causes: Gas gangrene, Food poisoning (Enterotoxin A), Soft tissue

infections in diabetics and Necrotizing bowel disease

Clostridium perfringens

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

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

Toxin: botulin

Key reaction: Lipase (+)

Causes:Botulism: Inhibits acetlycholine release from motor

neurons

Clostridium botulism

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

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 )

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 (+ )

Bacteroides fragilis

Bacteroides ureolyticus

Fusobacterium nucleatum

Fusobacterium necrophorum

Other Fusobacterium

Porphyromona spp.

Prevotella spp.

Negative Bacilli

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)

Bacteroides ureolyticus

Key reaction

• Urease (+)

Bile sensitive, Non-motile

Causes :• Respiratory infections•Intestinal tract infections

Gram negative rod

Kanamycin (S )Vancomycin (R )Colistin (S)

Fusobacterium nucleatum

Key reactions • Lipase (-)

• Indole (+)

Causes :

Metastatic brain abscess

Fusiform Gram negative

bacilli

Kanamycin (S )

Vancomycin (R )

Colistin (S)

Fusobacterium

necrophorum

Key reaction

• Lipase (+)

Causes :

Pertonsillar abscess in children and

young adult

Pleomorphic filamentous

gram negative rod

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)

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

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

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