Abstract

CARPINELLI, L et al. Frequency of beta-hemolytic streptococci serogroups in throat swabs of patients with pharyngitis. Mem. Inst. Investig. Cienc. Salud [online]. 2008, vol.6, n.1, pp.15-19. ISSN 1812-9528.

The Streptococcus pyogenes or group A beta-hemolytic streptococci (ABHS) is the most frequent cause of bacterial pharyngitis; its importance is due to the fact that it can trigger nonsuppurative sequela such as acute rheumatic fever and post-streptococcal acute glomerulonephritis. Cases of pharyngitis caused by non group A beta-hemolytic streptococci, particularly group C (CBHS) and G (GBHS), have been documented but their exact role is not clear. The objective of this retrospective study was to determine the frequency of the beta-hemolytic streptococcus serogroups isolated from throat swabs of children and adults who consulted at the department of Microbiology of the San Roque Laboratory in Asunción, Paraguay between June 2006 and June 2007. Swab samples were cultured on sheep blood agar plates and placed into a 5% CO2 incubator at 35ºC for 48h. Beta-hemolytic colonies were identified using standard microbiological methods. Out of 303 throat swab cultures, BHS were identified in 42 (13.9%) of which 25 (8,3%) corresponded to ABHS, 4 (1.3%) to CBHS and 13 (4.3%) to GBHS. When only beta-hemolytic streptococcus isolates were considered, 59.5% corresponded to group A, 9.5% to group C and 31% to group G. In conclusion, as 40.5% of the BHS isolates were non group A, group A should not be considered the only pathogenic streptococcus of the pharynx, and all serogroups should be identified and informed routinely for a correct diagnosis and treatment, as a measure to prevent nonsuppurative injuries that infection by these serogroups can trigger. Keywords:pharyngitis, group A beta-hemolytic streptococci (ABHS), group C beta-hemolytic streptococci (CBHS), group G beta-hemolytic streptococci GBHS).

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