No abstract

Aspirates of pus from periapical abscesses in 39 patients were studied for aerobic and anaerobic bacteria. Bacterial growth was present in 32 specimens. A total of 78 bacterial isolates (55 anaerobic and 23 aerobic and facultative) were recovered, accounting for 2.4 isolates per specimen (1.7 anaerobic and 0.7 aerobic and facultatives). Anaerobic bacteria only were present in 16 (50%) patients, aerobic and facultatives in 2 (6%), and mixed aerobic and anaerobic flora in 14 (44%). The predominant isolates were Bacteroides spp. (23 isolates, including 13 Bacteroides melaninogenicus group), Streptococcus spp. (20), anaerobic cocci (18), and Fusobacterium spp. (9). Beta-lactamase-producing organisms were recovered from 7 of the 21 (33%) specimens that were tested. This study highlights the polymicrobial nature and importance of anaerobic bacteria in periapical abscess.

To study the aerobic and anaerobic microbiology of liver and spleen abscesses and correlate the results with predisposing factors, potential causes and routes of infection, clinical and laboratory data of 48 patients with liver abscesses and 29 with spleen abscesses treated between 1970 and 1990 were reviewed retrospectively. In liver abscesses, a total of 116 isolates (2.4 isolates/specimen) was obtained; 43 were aerobic and facultative species (0.9 isolates/specimen) and 73 were anaerobic species or microaerophilic streptococci (1.5 isolates/specimen). Aerobic bacteria only were isolated from 12 (25%) abscesses, anaerobic bacteria only from eight (17%), and mixed aerobic and anaerobic bacteria from 28 (58%); polymicrobial infection was present in 38 (79%). In splenic abscesses, a total of 56 isolates (1.9 isolates/specimen) was obtained; 23 were aerobic and facultative species (0.8 isolates/specimen), 31 were anaerobic species or micro-aerophilic streptococci (1.1 isolates/specimen) and two were Candida albicans. Aerobic bacteria only were isolated from nine (31%) abscesses, anaerobic bacteria from eight (28%), mixed aerobic and anaerobic bacteria from 10 (34%) and C. albicans in two (7%); polymicrobial infection was present in 16 (55%). The predominant aerobic and facultative isolates were E. coli (5 isolates), Proteus mirabilis (3), Streptococcus group D (3), K. pneumoniae (3) and S. aureus (4). The predominant anaerobes were Peptostreptococcus spp. (1 1 isolates)

The microbiological and clinical characteristics of 83 patients with necrotizing fasciitis (NF) treated over a period of 17 years are presented. Bacterial growth was noted in 81 of 83 (98%) of specimens from patients with NF. Aerobic or facultative bacteria only were recovered in 8 (10%) specimens, anaerobic bacteria only were recovered in 18 (22%) specimens, and mixed aerobic-anaerobic floras were recovered in 55 (68%) specimens. In total, there were 375 isolates, 105 aerobic or facultative bacteria and 270 anaerobic bacteria, for an average of 4.6 isolates per specimen. The recovery of certain bacteria from different anatomical locations correlated with their distribution in the normal flora adjacent to the infected site. Anaerobic bacteria outnumbered aerobic bacteria at all body sites, but the highest recovery rate of anaerobes was in the buttocks, trunk, neck, external genitalia, and inguinal areas. The predominant aerobes were Staphylococcus aureus (n ‫؍‬ 14 isolates), Escherichia coli (n ‫؍‬ 12), and group A streptococci (n ‫؍‬ 8). The predominant anaerobes were Peptostreptococcus spp. (n ‫؍‬ 101), Prevotella and Porphyromonas spp. (n ‫؍‬ 40), Bacteroides fragilis group (n ‫؍‬ 36), and Clostridium spp. (n ‫؍‬ 23). Certain clinical findings correlated with some bacteria: edema with B. fragilis group, Clostridium spp., S. aureus, Prevotella spp. and group A streptococci; gas and crepitation in tissues with members of the family Enterobacteriaceae and Clostridium spp.; and foul odor with Bacteroides spp. Certain predisposing conditions correlated with some organisms: trauma with Clostridium spp.; diabetes with Bacteroides spp., members of the family Enterobacteriaceae, and S. aureus; and immunosuppression and malignancy with Pseudomonas spp. and members of the family Enterobacteriaceae. These data highlight the polymicrobial nature of NF.