Microbiology of acute complicated bacterial sinusitis at the University of the Witwatersrand.
A retrospective chart review study at two referral hospitals identified 226 consecutive surgical patients with acute complicated sinusitis. One hundred and fifty-nine male and 67 female patients, with a mean age of 16.5 (standard deviation 0.7) years, underwent external fronto-ethmoidectomy with maxillary sinus washout and 13 had a concurrent craniotomy. A total of 233 micro-organisms were isolated from 163 patients(72.1%), and 63 (27.9%) were culture-negative. Positive isolates included Streptococcus milleri (18.5%), Staphylococcus aureus (12.4%), beta-haemolytic streptococci (10.8%), coagulase-negative staphylococci (8.6%), Haemophilus influenzae (8.6%) and the anaerobes, Peptostreptococcus (6.4%) and Prevotella (4.7%) species. The prevalences of S. pneumoniae (2.6%), methicillin-resistant S. aureus (MRSA) (1.3%) and Moraxella catarrhalis (0.4%) were low. Polymicrobial disease was present in 56 patients (34.4%). There was a significant difference between the two hospitals in the prevalences of some bacteria (p<0.05). Antibiotic resistance was highest towards the penicillins (64.3%) and cephalosporins (12.5%). Effective empiric treatment was achieved with metronidazole and a choice of amoxicillin-clavulanate or ampicillin plus cloxacillin or penicillin plus chloramphenicol. The polymicrobial nature and severity of complicated sinusitis warrants a de-escalation approach to antimicrobial therapy. The combination of beta-lactamase-resistant penicillins and metronidazole is a reasonable choice for initial empiric antibacterial therapy. Selection of drugs for empirical antibiotic therapy in patients with acute complicated sinusitis should be supported by knowledge of the local prevalence and antimicrobial susceptibilities of bacteria isolated from patients.