Bacteriology of deep neck abscesses: a retrospective review of 96 consecutive cases.

INTRODUCTION This study aimed to review the microbiology of deep neck abscesses and identify the factors that influence their occurrence. METHODS A retrospective chart review was done of patients diagnosed with deep neck abscesses at the Department of Otorhinolaryngology, Tan Tock Seng Hospital, Singapore between 2004 and 2009. The data of 131 deep neck abscess patients were reviewed, and those with positive pus culture were included in the study. Logistic regression was applied to analyse and compare the incidence of common organisms in various conditions (age, gender, aetiology and effects of diabetes mellitus). RESULTS Of the 96 patients recruited, 18 had polymicrobial cultures. The leading pathogens cultured were Klebsiella (K.) pneumoniae (27.1 percent), Streptococcus milleri group (SMG) bacteria (21.9 percent) and anaerobic bacteria-not otherwise specified (NOS) (20.8 percent). K. pneumoniae (50.0 percent) was over-represented in the diabetic group. SMG bacteria (68.8 percent) and anaerobic bacteria-NOS (43.8 percent) were most commonly isolated in patients with odontogenic infections. K. pneumoniae was found more commonly among female patients (39.3 percent). The distribution of the three leading pathogens between patients aged below 50 years and those 50 years and above was comparable. K. pneumoniae was the commonest organism cultured in parapharyngeal space abscesses, while the submandibular space and parotid space most commonly isolated SMG bacteria and Staphylococcus aureus, respectively. CONCLUSION Broad-spectrum antibiotics are recommended for treating deep neck abscesses. Empirical antibiotic coverage against K. pneumoniae infection in diabetic patients, and SMG and anaerobic bacteria in patients with an odontogenic infection, is advocated. Routine antibiotic coverage against Gram-negative bacteria is not paramount.