Objectives: To evaluate the accuracy of endoscopically guided middle meatal aspiration culture by comparing the culture results between middle meatal aspiration using the modified aspiration instrument and direct maxillary antral tap.
Material and Method: Sixteen patients with chronic rhinosinusitis underwent functional endoscopic sinus surgery (FESS) were enrolled. Both endoscopically middle meatal aspiration culture (EMAC) using modified aspiration instrument and direct antral tap culture (ATC) were performed before FESS. Microbiologic data were compared and analyzed for any statistical differences between EMAC and ATC.
Results: The positive culture rates were 93.75% in both EMAC and ATC groups. Aerobic and facultative anaerobic bacteria were found in 87.5% of EMAC group and 81.25% of ATC group. The two most common bacteria in both groups were coagulase-negative Staphylococcus and Staphylococcus aureus. The association between EMAC and ATC was strong to moderate (13/16) 81.25%.
Conclusion: EMAC appears to be a valuable alternative to ATC for guiding bacterial-specific therapy in chronic rhinosinusitis. This modified aspiration instrument should be useful in clinical practice and serve as a cost effective procedure.

Keywords: Chronic rhinosinusitis, Culture, Aspiration instrument, Middle meatal aspiration, Antral tap