Assessment of trends in antimicrobial resistance in chronic rhinosinusitis

We performed a cross-sectional review of a prospective database to determine the contemporary incidence and temporal patterns of antimicrobial resistance in chronic rhinosinusitis (CRS).

A microbiological database was retrospectively reviewed to extract all endoscopically obtained paranasal sinus cultures from 2001 through 2005 in adult patients with CRS. The culture data were tabulated according to bacterial species and representative antibiotic resistances for methicillin, erythromycin, clindamycin, gentamicin, tetracycline, sulfamethoxazole, and levofloxacin. The data were analyzed to determine whether increasing rates of antibiotic resistance developed over the study years. Further analysis was conducted for methicillin-resistant Staphylococcus aureus (MRSA) species to determine prevalence trends and antibiotic resistance trends for MRSA versus other species.

We analyzed 701 bacterial isolates among 392 culture samples. Staphylococcus aureus was the most commonly isolated organism (19.0%). Antibiotic resistance significantly increased for erythromycin over the study (maximum resistance rate, 69.7% in 2005; p = .009), remained unchanged for methicillin, clindamycin, levofloxacin, and sulfamethoxazole (p = .366 to p = .397), and trended downward for gentamicin (p = .180) and tetracycline (p = .120). Nineteen percent of S. aureus species were found to be MRSA, but MRSA-specific antibiotic resistance rates did not change over the course of the study (all p > or = .222). In aggregate, MRSA species exhibited statistically significant higher rates of resistance to each antibiotic tested than did non-MRSA bacteria.

Antibiotic resistance seems to be emerging for erythromycin at a rate higher than for other antibiotics. Although not increasing in prevalence, MRSA maintains a significant presence in CRS with associated increased levels of antibiotic resistance.