Bacteriologic and serologic aspects of streptococcal pharyngitis in Mexico City
León, A.P.; Cano, C.; Argott, E.E.
Boletin de la Oficina Sanitaria Panamericana. Pan American Sanitary Bureau 99(1): 53-61
1985
ISSN/ISBN: 0030-0632 PMID: 2932128 Document Number: 249107
A study was made of 1499 cases of pharyngitis diagnosed in Mexico city between 1970 and 1982 to determine the frequency and tendency of alpha, beta and gamma hemolytic streptococci and of A and non-A serologic groups. For the same purpose, 150 controls who were healthy or had diseases other than pharyngitis were studied from 1980 to 1982 and compared with 288 cases of pharyngitis observed during the same period. Streptococci of one or more hemolytic groups were isolated in 98.6% of the cases of pharyngitis. Alpha streptococci were isolated in 40.6% of the cases, beta streptococci in 13.7%, and gamma organisms in 88.7%. In the comparative studies, streptococci of one or more hemolytic groups were isolated in 99.0% of the patients with pharyngitis and from 71.0% of the controls. Alpha streptococci were isolated in 21.5% of the pharyngitis cases and in 19.3% of the controls, beta streptococci in 13.2% and 8.0%, and gamma streptococci in 96.1% and 64.0%, respectively. From 1970 to 1982 the frequency of findings of alpha streptococci declined, that of beta organisms held stationary, and that of gamma organisms rose markedly. Group A streptococci were isolated in 21.4% of the cases of pharyngitis, and antistreptolysin 0 presented titers of diagnostic value (.gtoreq. 200 Todd units) in 36.6% of the cases. The feature that distinguishes this study from others is the high frequency of isolation of gamma hemolytic streptococci in cases of pharyngitis.