Obligate Anaerobes
Obligate anaerobic bacteria:
Anaerobic bacteria require growth in the absence of oxygen. They require special workup in the clinical lab and specimen collection is very important and must be as sterile as possible due to their presence as normal flora on mucosal surfaces. Anaerobic bacteria results can be differentiated using the following flow chart.
Other notes on anaerobic bacteria:
C. perfringens – anaerobic, double zone of beta hemolysis, gas gangrene
Clostridium tetani – round terminal spores, lockjaw
Clostridium difficile – antibiotic associated colitis
Porphyromonas/Prevotella – black pigment and brick red fluorescence under UV light
Fusibacteria – long slender rods
Actinomyces – sulfur granules, molar teeth colonies
HACEK organisms:
The HACEK organisms are grouped together due to their dysgonic (slow or poor) growth. HACEK stands for:
H = Haemophilus
A = Actinobacillus
C = Cardiobacterium
E = Eikenella
K = Kingella
Eikenella corrodens – normal flora of upper respiratory tract and mouth, agar pitting, bite wounds, bleach smell
Kingella kingae – narrow zone of beta-hemolysis on SBA, endocarditis, normal flora of upper respiratory tract and urogenital tract.
C, E, and K of HACEK are oxidase +
Cardiobacterium – normal flora of upper respiratory tract, associated with endocarditis
Capnocytophaga – dog bites, gliding motility