Drift in the bacteriology of chronic suppurative otitis media and methicillin-resistant Staphylococcus aureus as an emerging pathogen: an experience

Abstract

Background: Chronic suppurative otitis media (CSOM) is a condition of the middle ear, which is characterized by persistent or recurrent discharge. Many studies done in CSOM have found the predominance of Gram negatives in the ear discharge, with Pseudomonas and Proteus species as the most commonly identified aerobic organisms. Gram positives [Staphylococcus aureus, methicillin-resistant S. aureus (MRSA)] are found but are less common. Background: To study the aerobic culture and sensitivity results of pediatric patients with CSOM attending the outpatient department, with special emphasis on MRSA. Materials and Methods: One hundred-fifteen pediatric patients with CSOM who fulfilled the inclusion and exclusion criteria were prospectively studied. They showed chronic ear discharge and had not received antibiotics for the previous 7 days. Swabs were taken from the middle ear under microscope and cultured for only aerobic bacteria. The antimicrobial susceptibility testing was performed using an agar disk diffusion method according to the guidelines of Clinical and Laboratory Standards Institute. Result: The male subjects were commonly involved. There were 113 positive cultures for organisms from the 115 patients. The most common organism was Staphylococcus seen in 65% of patients [35% methicillin-sensitive Staphylococcus aureus (MSSA) and 30% MRSA], followed by Pseudomonas sp. 13%, and Escherichia coli in 7%. The majority of Staphylococcus sp. were MSSA (53%), followed by MRSA (44%). Gram positives were seen in 65% of cases, while gram negatives in 31% of cases. We noticed a drift in bacteriology from gram negatives to gram positives. MRSA were sensitive to linezolid, vancomycin, and clindamycin, whereas resistant to azithromycin, cefuroxime, and ciprofloxacin. The majority of MRSA were seen in patients with central perforation with ossicular discontinuity. The percentage of MRSA seen in our study was quite high. Conclusion: In this study, we can see a drift in bacteriology of CSOM from gram negative to gram positive, and MRSA is emerging as an important pathogen in CSOM. Empirical antibiotics should be directed to gram positives, and especially, MRSA should be taken into consideration.