Deep neck abscess: an analysis of microbial etiology and the effectiveness of antibiotics.

The objective was to demonstrate the aerobic and anaerobic microbiology of deep neck space abscess and to analyze the coverage rate of different empiric antimicrobial agents. A retrospective review of hospitalized patients with deep neck abscess diagnosed at a tertiary-care, general hospital between April 2001 and October 2006. The study enrolled 100 patients. The bacterial cultures of 89 patients yielded positive results (89%). The predominant aerobes were viridans streptococci, Klebsiella pneumoniae, and Staphylococcus aureus. The predominant anaerobes included species of Prevotella, Peptostreptococcus, and Bacteroides. Five different combinations of empiric antibiotics, namely regimen 1: penicillin G and clindamycin and gentamicin, regimen 2: ceftriaxone and clindamycin, regimen 3: ceftriaxone and metronidazole, regimen 4: cefuroxime and clindamycin, and regimen 5: penicillin and metronidazole, were compared using the antimicrobial susceptibility of 89 cases. The coverage rates of regimens 1, 2, 3, 4, and 5 were 67.4%, 76.4%, 70.8%, 61.8%, and 16.9%, respectively. The coverage of regimen 5 was considerably worse than that of the other four regimens (p < 0.001). Regimen 2 was significantly better than regimen 4 (p < 0.001). Regimen 2 had better coverage than regimens 1 (p = 0.096) and 3 (p = 0.302), but the difference was not statistically significant. This study demonstrates the bacteriology of deep neck abscess and analyzes the coverage rate of different empiric antimicrobial agents. Regimens 1, 2, and 3 could be good candidates for empiric antibiotics. Pathogen-directed antimicrobial therapy should be adjusted after the culture results are obtained.