Aneaerobic Infections Flashcards
How can you tell it’s an anaerobic infections?
Foul smelling discharge
Gas in necrotic tissue
What are the predisposing conditions for an anaerobic infection
Pulmonary aspiration
Bowel surgery
Poor dental hygiene
Human/animal bites
Trauma
Abortion
Where do most anaerobic infections occur?
Where Oxygen is low and access to endogenous bacterial is high
Occur because of:
A. Wound
B. Impaired blood supply
C. Tissue necrosis
What else should you keep in mind when you suspect an anaerobic infection?
Almost all anaerobic infections are MIXED
Anaerobe + another anaerobe or facultative aerobe
What’s important to remember when treating anaerobic infections?
Knowledge of local flora helps with therapy
Cultures take too long
How would you treat oral infections?
Penicilin sensitive
Usually gram + cocci and gram - rods
How would you generally treat intra abdominal infections?
Usually penicillin resistant
Gram - rods, mixed anaerobic infection
How do you culture anaerobic bacteria?
Carefully collect specimen and directly inject into special tubes
VERY LITTLE EXPOSURE TO AIR
Don’t forget to gram stain
What are the anaerobic gram negative rods?
Bacteroides Fragilis
Prevotella Melaninogenicus
Fusobacterium Species
What’s the most common anaerobic gram negative rod?
B. Fragilis
Large numbers in Large intestine
B. Fragilis Growth facts
Resists bacteriocidal bile
May tolerate trace levels of oxygen
What are most common anaerobes found in septicemia?
B. Fragilis and C. Perfringens
80% of anaerobic septicemias
(8% of total)
What are common B. Fragilis infections?
Intraabdominal (bowel rupture)
Female genital infections (pelvic abscess)
Septicemia
How would you treat a suspected B.F. Infection?
NOT PENICILLIN
-resistant
CEPHALOSPORIN
-eg cefoxitin
What is BF’s major virulence factor?
CAPSULE
Only capsulated strains produce abscess
What’s a common cause for oral infections?
Prevotella melaninogenicus
What’s noticeable about P. Melaninogenicus cultures?
BLACK PIGMENT
From Hemin
Found on blood agar plates and infected tissues
Prevotella Melaninogenicus
Oral infections
(Penicillin and oxygen sensitive)
Also sometimes found in genital infections
What do Fusobacterium look like?
Tapered Ends (needle shape)
very thin
Where do Fusobacterium infect?
Oral, lung, abdominal
What are the anaerobic gram positive rods?
Clostridium (pore forming)
Bifidobacterium
Corynebacterium (diptheroids)
Lactobacillus
Actinomyce
Chief suspect when sulfur granules present?
Actinomyces
Yellow granules seen in lesions composed of microcolonies
What are common actinomyces infections
Oral and Dental abscess,
Lung abscess,
abdominal abscess
Where is actinomyces normally found?
Oral pharynx and GI tract
What are the anaerobic gram positive cocci?
Peptostreptococcus
Peptococcus
Who is streptococci’s anaerobic twin?
Peptostreptococcus
Gram + cocci in chains
Where is peptostrep usually found?
Commensal bacteria of the:
- Mouth
- Urogenital tract
- GI tract
Peptostrep infections are
Widespread and usually involve other anaerobes
EXCEPT
- pleuro-pulmonary infection
- brain abscesses
- OB-GYN infections
First drug of choice for anaerobes?
penicillin
EXCEPT below the diaphragm,
-> Used in conjunction with others
Treating a mixed aerobe-anaerobe infection
aminoglycoside + anaerobe specific
Eg. Gent + clinda
Or Gent + cefoxitin
How would you treat an abscess?
SURGICAL DRAINAGE!
Antibiotics can’t get inside
Other antibiotics for anaerobes
Clindamycin
Cephalosporins (cefoxitin)
-especially for B. FRAGILIS
Chloramphenicol
Metronidazole
