Clinical features and aerobic and anaerobic microbiological characteristics of cellulitis
I. Brook and E. H. Frazier
Department of Pediatrics, Naval Hospital, Bethesda, Md., USA.
OBJECTIVES: To investigate the aerobic and anaerobic microbiological
characteristics of cellulitis and correlate them with the infection site.
DESIGN: Of 342 specimens, 64 obtained using needle aspiration and 278 using
swabs were studied over 10 years. RESULTS: Bacterial growth was noted in 15
(23%) of the 64 needle aspirates and 259 (93%) of the 278 swab aspirates.
The microbial results of the 15 specimens obtained through needle
aspiration are separately presented. Aerobic or facultative bacteria only
were present in 138 (53%) of swab samples, anaerobic bacteria only in 69
(27%), and mixed aerobic-anaerobic flora in 52 (20%). In total, there were
582 isolates, 247 aerobic or facultative and 335 anaerobic bacteria, with
an average of 2.2 isolates per specimen. The predominance of certain
isolates in different anatomical sites correlated with their distribution
in the normal flora adjacent to the infected site. The highest recovery
rates of anaerobes was from the neck, trunk, groin, external genitalia, and
leg areas. Aerobes outnumbered anaerobes in the arm and hand. The
predominant aerobes were Staphylococcus aureus, group A streptococci, and
Escherichia coli. The predominant anaerobes were Peptostreptococcus sp,
Bacteroides fragilis group, Prevotella and Porphyromonas sp, and
Clostridium sp. Certain clinical findings correlated with the following
organisms: swelling and tenderness with Clostridium sp, Prevotella sp, S
aureus, and group A streptococci; regional adenopathy with B fragilis
group; bulbous lesions with Enterobacteriaceae; gangrene and necrosis with
Peptostreptococcus sp, B fragilis group, Clostridium sp, and
Enterobacteriaceae; foul odor with Bacteroides sp; and gas in tissues with
Peptostreptococcus sp, B fragilis group and Clostridium sp. Certain
predisposing conditions correlated with the following organisms: trauma
with Clostridium sp; diabetes with Bacteroides sp, Enterobacteriaceae, and
S aureus; and burn with Pseudomonas aeruginosa. CONCLUSION: These data
highlight the polymicrobial nature of cellulitis.
