Serotipos y susceptibilidad antimicrobiana de Streptococcus agalactiae / Serotypes and antimicrobial susceptibility of Streptococcus agalactiae

Background : Streptococcus agalactiae or group B streptococcus, GBS, is the leading cause of neonatal and maternal infections and an opportunistic pathogen in adults with underlying disease. In the last decade, a dramatic increase in the resistance of this microorganism to erythromycin and clindamycin has been observed. Aim: To determine the serotype distribution and antimicrobial susceptibility of isolates of S agalactiae collected from infections and colonization and to assess the genetic mechanisms of macrolide and clindamycin resistance. Material and methods: A total of 100 GBS isolates were collected between 1998 and 2002, in Santiago, Chile. They were isolated from the amniotic fluid from patients with premature rupture of membranes (7 isolates), blood from neonatal sepsis (10 isolates), neonate colonizations (2 strains), skin and soft tissue infections (7 isolates), urinary tract infections (5 isolates), genital infections (3 isolates), articular fluid (one isolate), and 65 strains were recovered from vaginal colonization55. Results: Serotypes Ia, II and III were the predominant serotypes identified in our study, accounting for 90 (90 percent) of the strains. Five isolates belonged to serotypes Ib (5 percent) and two (2 percent) to serotype V respectively; no strains belonging to serotype IV were found. All strains were susceptible to penicillin G, ampicillin and cefotaxime, and four isolates (4 percent) were resistant to both erythromycin (MIC >64 µg/ml) and clindamycin (MIC >64 µg/ml). The strains had a constitutive macrolide-lincosamide-streptogramin (cMLSB) resistance phenotype and the erm(A) gene was present in the four isolates. Conclusions: Serotypes Ia, II and III were the predominant serotypes in this study. All strains were susceptible to penicillin G, ampicillin and cefotaxime, and four (4 percent) strains were resistant to both erythromycin and clindamycin. The cMLSB resistance phenotype, and the erm(A) gene was detected in resistant strains (Rev MÚd Chile 2004; 132: 549-55).

Infecciones respiratorias agudas intrahospitalarias / Hospital acute respiratory infections

Se estudiaron 31 lactantes ingresados entre mayo y agosto de 1988 a una sala índice del Servicio de Pediatría, Hospital San Juan de Dios, Santiago de Chile, con diagnóstico de IRA baja, con el propósito de conocer la incidencia de la infección nosocomial respiratoria en la primera semana de hospitalización. En cada niño se realizó estudio virológico y bacteriológico seriado. En 13 de los 31 pacientes se detectó uno o más agentes virales nuevos en la segunda muestra (18 nuevos aislamientos en total), los que podrían haber sido adquiridos durante la hospitalización; los segundos virus fueron: Ad (n = 8), VRS (n = 5) y CMV (n = 5). No se detectaron cambios significativos de la flora bacteriana en el período estudiado