Clinical
Treatment
Specimen
transport and
processing
Environmental
Conditions
Negative Bacilli
Positive Bacilli
Anaerobic cocci
 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
Peptostreptococcus
Vieonella??? Get correct spelling
Peptostreptococcus
(Peptoniphilus)
spp.
Intestinal gram positive
cocci
P. anaerobius
• Elongated
• Produce sweet odor due to
the presence of isocaproic
acid
Key reactions
• Nitrate (+)
• SPS –sensitive
• Indole (-)
P. assacharolyticus
Form tetrads or pairs
Key reactions :
SPS resistant, Indole (+),
Nitrate (-)
Causes:
•Head, neck , genital
and gut infections
Indigenous to oral
cavity, upper
respiratory, G.I and
genitourinary tract
Kanamycin (S )
Vancomycin (R )
Colistin (S)
Viellonella
species
Small
Gram negative cocci
Key reactions
•Nitrate (+)
•Non-fluorescent, may
pigment red
Causes :
Endocarditis and
bacteremia
Clostridium species
Others ?????
Clostridium
spp.
Gram positive rods
Four common species
• Clostridium perfringens
• Clostridium difficile
• Clostridium tetani
• Clostridium botulism
• Other Clostridium
Produce Virulence
factors that are
responsible for
infections
Causes :
• Food poisoning
Spore formers
Found commonly
in stool specimen
•Gas gangrene(myonecrosis)
•Neoplasm s
•Lock jaw
•Pseudomembraneous
colitis
 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
 Subterminal spore
 Chartreuse fluorescence
 Key reactions
 Ferment fructose
 Lecthinase (-), Lipase (-)
 Causes:
 Pseudomonas colitis and Antibiotic associated diarrhea
(AAD) due to enterotoxin A and B
 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
 Toxin: botulin
 Key reaction:
 Lipase (+)
 Causes:
 Botulism: Inhibits acetlycholine release from motor neurons
Clostridium novyi
Clostridium septicum
 Beta hemolytic
 Rapid swarmer
 Characteristic: medusa head,
subterminal spores
 Key reactions:
 Lecithinase (+), lipase
(+), indole (-), urease (-)
 Causes:
Gas gangrene (myonecrosis) and toxic
shock
 Key reactions:
 Lipase (-), Indole (-)
 Causes:
Neoplasm of the colon, breast
leukemia, lymphoma, enterocolitis.
myonecrosis
Normal flora in the
oral cavity, G.I. and
female genital tract
Key reactions
• Catalase (-)
•Cephalosporin (R)
•Vancomycin (R )
Lactobacillus
Gram positive
Non-spore forming bacilli
Infections caused:
Bacterial vaginosis
Pelvic inflammatory
disease
•Protect female genital tract
• Produce lactic acid to
lower vaginal pH
Normal flora of the
skin
Proprionibacterium
acnes
Gram positive
Non-spore forming bacilli (appear
as diptheroids)
Reactions
• Catalase (+)
•Indole (+)
•Nitrate (+ )
Can cause:
Subacute bacterial
endocarditis
Bacteremia
Bacteroides fragilis
Bacteroides ureolyticus
Fusobacterium nucleatum
Fusobacterium necrophorum
Other Fusobacterium
Porphyromona spp.
Prevotella spp.
Gram negative rod
Penicillin (R )
Kanamycin (R )
Vancomycin (R )
Colistin (R )
Clindamycin (S)
Key reactions
•Catalase (+)
•Indole (-)
•Nitrate (-)
Bacteroides
fragilis
Bile tolerant, Nonmotile
Causes :
• Inflammation of the
intestinal wall
• Septic abortion
• Thrombosis
•G.I. infections
Gram negative rod
Kanamycin (S )
Vancomycin (R )
Colistin (S)
Key reaction
•Urease (+)
Bacteroides
ureolyticus
Bile sensitive, Nonmotile
Causes :
• Respiratory infections
•Intestinal tract infections
Fusiform
Gram negative
bacilli
Kanamycin (S )
Vancomycin (R )
Fusobacterium
nucleatum
Colistin (S)
Key reactions
• Lipase (-)
• Indole (+)
Causes :
Metastatic brain
abscess
Pleomorphic
filamentous gram
negative rod
Fusobacterium
necrophorum
Causes :
Key reaction
•Lipase (+)
Pertonsillar abscess in
children and young
adult
Normal flora in the
oral, G.I and vaginal
area
Kanamycin (R )
Vancomycin (R )
Colistin (S)
Penicillin (R)
Prevotella
melaninogenica
Gram negative
coccobacilli
• Produces foul odor
• Slow producer of
protoporphin
Causes :
Lung and dental
infections

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
 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
 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