Isolation of methicillin resistant Staphylococcus aureus from the surface and core of tonsils in children

The rate of recovery methicillin resistant Staphylococcus aureus (MRSA) in tonsils that were removed because of recurrent Group A-beta-hemolytic streptococci (GABHS) tonsillitis was not previously reported. MRSA may serve as a potential source for the spread of these organisms to other body sites as well to other individuals. This study investigated the rate of recovery of MRSA as well as other aerobic organisms from tonsils that were removed because of recurrent GABHS infection.

Core and surface tonsillar cultures for aerobic bacteria were obtained from 44 children who had tonsillectomy because of recurrent GABHS tonsillitis.

A total of 167 aerobic isolates were recovered from the core of the tonsils (3.8/specimen) and 151 (3.4/specimen) were isolated from the surface. The predominant isolates were alpha-hemolytic streptococci, GABHS, S. aureus, gamma-hemolytic streptococci, Haemophilus influenzae and Moraxella catarrhalis. Concordance in the recovery of all organisms was noted in 117 instances. Certain organisms (i.e. GABHS, S. aureus) were recovered more often from the tonsillar cores, where other (i.e. alpha-hemolytic streptococci, gamma-hemolytic streptococci) were recovered more often from the tonsillar surface. Forty-four beta-lactamase-producing bacteria (BLPB) were recovered from 32 (75%) of the tonsillar cores, and 28 were isolated from 23 (52%) of the tonsillar surfaces. The predominant BLPB were S. aureus, H. influenzae and M. catarrhalis. Seven isolates of MRSA were recovered from the cores and two were isolated from the surface. Five of the core isolates and the two surface isolates were also BLPB. All of the MRSA isolates were resistant to oxacillin, penicillin and erythromycin and were susceptible to clindamycin, trimethoprim-sulfamethoxazole and vancomycin.

These data demonstrated that in recurrently GABHS infected tonsils, BLPB was recovered from over 75% of the tonsillar cores, core tonsillar cultures yielded more GABHS and S. aureus, and MRSA was isolated from 16% of the tonsils.