A comparison of endoscopic culture techniques for chronic rhinosinusitis

Recent evidence suggests that endoscopically obtained cultures from the middle meatus give comparable results to antral puncture for acute sinusitis. The best method for obtaining middle meatal cultures remains somewhat controversial because it has been theorized that specimens obtained with a swab are contaminated easily. This study compares endoscopic culture results from two different methods: swab and aspiration. Specifically, this study sought to determine whether or not the culture contamination rate is higher using the swab versus an aspiration technique.

One hundred consecutive culture specimensfrom 81 chronic rhinosinusitis patients were compared. Fifty cultures were obtained using a swab technique (group I) and another 50 cultures were obtained by aspirating pathological material into a sterile suction trap (group II). The patient populations in each group were similar; there were no differences in terms of age, gender, comorbid medical conditions, or prior medical therapy. Cultures were considered contaminated if they yielded normal nasal flora or if rare or few Staphylococcus coagulase-negative colonies grew after no bacteria was identified in gram stain. Staphylococcus aureus, Staphylococcus coagulase-negative, and Pseudomonas aeruginosa were the three most common organisms in both groups.

Gram-negative bacteria were noted in 21/60 (35%) positive cultures. Although the contamination rate of the suction aspiration group (14%) was less than the endoscopic swab group (10%), this did not approach statistical significance (p = 0.75).

Data from this study suggest that endoscopically guided aspiration of pathological material is no better than properly obtained swabs in directing antimicrobial therapy for chronic rhinosinusitis.