Aerobic and anaerobic bacteriology of wounds and cutaneous abscesses

The aerobic and anaerobic microbiologic characteristics of 584 wounds and 676 skin or soft-tissue abscesses were studied and correlated with the infection site. In wounds, aerobic or facultative bacteria only were present in 223 specimens (38%), anaerobes only in 177 specimens (30%), and mixed flora in 184 specimens (32%). In total there were 1470 isolates, 558 aerobic and 912 anaerobic, an average of 2.5 isolates per wound (1.6 anaerobic and 0.9 aerobic isolates). In abscesses, aerobic or facultative bacteria were recovered in 177 specimens (26%), anaerobes only in 243 specimens (36%), and mixed flora in 256 specimens (38%). In total there were 1702 isolates, 602 aerobic and 1100 anaerobic, an average of 2.5 isolates per abscess. The highest rates of anaerobes in wounds were in the inguinal, buttocks, and trunk areas and in abscesses in the perirectal, external genitalia, neck, and inguinal areas. The predominant aerobic organisms were Staphylococcus aureus (363 isolates), group A streptococci (98 isolates), and Escherichia coli (97 isolates). The predominant anaerobic organisms were Bacteroides species (986 isolates), Peptostreptococcus species (559 isolates), Clostridium species (153 isolates), and Fusobacterium species (109 isolates). The predominance of certain isolates in certain anatomical sites was correlated with their distribution in the normal flora adjacent to the infected site. These data highlight the polymicrobial nature of wounds and cutaneous abscesses.