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Microbiology
OPEN
TABLE 3
(bacteriologic results in ten cases of lung abscess)
OPEN TABLE
4a , TABLE
4b and TABLE
4c (with lists of bacteria, reference)
– anaerobic or mixed infection 78% of cases.
–
aerobic alone only 16% of the time.
–
main culprits:
• Gram + anaerobic cocci
• pigmented Gram Ð bacilli
• Fusobacteria
–
in nosocomial infection, must consider Staph. aureus, and enteric Gram
– bacilli.
–
often do not need invasive diagnostic techniques. Can treat empirically.
–
immunocompromised patients, do not forget:
• Aspergillus, Legionella, Cryptococcus, Pseudomonas, Nocardia
• AIDS population usually get cavitary upper lobe lesions, and lack
typical aspiration risk factors
–
immunocompetent patients, must consider:
• endemic fungi (Histoplasmosis, Coccidioides, Blastomyces)
• parasitic (Entamoeba, Echinococcus)
• TB
–
Streptococcus pneumoniae rarely causes lung abscesses. If it does, it
is usually in the context of obstruction, or of a mixed infection or superinfection.
However, the type 3 strain can cause lung abscess as an isolated infection,
because of its thick mucoid capsule.
–
antiobiotic resistance increasing (esp. Bacteroides resistance to penicillin)
Open TABLE
5 (antibiotic resistance)
– have seen treatment failures to penicillin that have responded
to clindamycin.
