Phenotypic and genotypic characterization of Streptococcus agalactiae in pregnant women: first study in a province of Argentina

Group B Streptococcus (GBS) is the leading cause of neonatal infections. Our purpose was to characterize GBS colonization in pregnant women, current serotypes, resistance phenotypes and genes associated with virulence. In Misiones, Argentina, there are no previous data on this topic. Vaginal-rectal swabs from 3125 pregnant women were studied between 2004 and 2010. GBS strains were identified by conventional and serological methods (Phadebact Strep B Test, ETC International, Bactus AB, Sweden). Serotypes were detected using Strep-B Latex (Statens Serum Institut, Denmark). Resistance phenotypes were determined by the double-disk test. Genes were studied by PCR. Maternal colonization was 9.38%. Resistance to erythromycin was 11.6%, and the constitutive phenotype was the predominant one. Serotype Ia was the most frequent, whereas serotypes IV, VI, VII and VIII were not detected. The lmb, bca and hylB genes were detected in more than 79% of the strains. In this study, the colonization rate with GBS and the serotype distribution were compared with studies reported in other areas of the country. The high resistance to erythromycin in Misiones justifies performing antibiotic susceptibility testing. The serotype distribution, the genes encoding putative virulence factors, and the patterns of resistance phenotypes of GBS may vary in different areas. They thus need to be evaluated in each place to devise strategies for prevention.

Antibiotic susceptibility patterns and prevalence of group B Streptococcus isolated from pregnant women in Misiones, Argentina / Sensibilidade a antibióticos e prevalência de Streptococcus do grupo B em mulheres grávidas em Missiones, Argentina

This study was performed to determine the susceptibility patterns and the colonization rate of Group B Streptococcus (GBS) in a population of pregnant women. From January 2004 to December 2006, vaginal-rectal swabs were obtained from 1105 women attending Dr. Ramón Madariaga Hospital, in Posadas, Misiones, Argentina. The carriage rate of GBS among pregnant women was 7.6 percent. A total of 62 GBS strains were randomly selected for in vitro susceptibility testing to penicillin G, ampicillin, tetracycline, levofloxacin, gatifloxacin, ciprofloxacin, quinupristin-dalfopristin, linezolid, vancomycin, rifampicin, trimethoprim-sulfametoxazol, nitrofurantoin, gentamicin, clindamycin and erythromycin, and determination of resistance phenotypes. No resistance to penicillin, ampicillin, quinupristin-dalfopristin, linezolid, and vancomycin was found. Of the isolates examined 96.8 percent, 98.3 percent, 46.8 percent, and 29.0 percent were susceptible to rifampicin, nitrofurantoin, trimethoprim-sulfametoxazol and tetracycline, respectively. Rank order of susceptibility for the quinolones was: gatifloxacin (98.4 percent) > levofloxacin (93.5 percent) > ciprofloxacin (64.5 percent). The rate of resistance to erythromycin (9.7 percent) was higher than that of other reports from Argentina. High-level resistance to gentamicin was not detected in any of the isolates. Based on our finding of 50 percent of GBS isolates with MIC to gentamicin equal o lower than 8 µg/ml, a concentration used in one of the selective media recommended for GBS isolation, we suggested, at least in our population, the use of nalidixic acid and colistin in selective media with the aim to improve the sensitivity of screening cultures for GBS carriage in women.

Esse estudo objetivou determinar os padrões de sensibilidade a antibióticos e as taxas de colonização de Streptococcus do grupo B (GBS) em uma população de mulheres grávidas. Entre janeiro de 2004 e dezembro de 2006, foram obtidos swabs vaginais-retais de 1105 mulheres no Hospital Dr. Ramon Madariaga, em Posadas, Missiones, Argentina. A positividade para GBS nas mulheres grávidas foi 7,6 por cento. Um total de 62 cepas de GBS foi selecionado ao acaso para testes in vitro de sensibilidade a penicilina G, ampicilina, tetraciclina, levofloxacina, gatifloxacina, ciprofloxacina, quinupristina-dalfopristina, linezolida, vancomicina, rifampicina, trimetoprim-sulfametoxazol, nitrofurantoína, gentamicina, clindamicina e eritromicina, e determinação dos fenótipos de resistência. Não foi encontrada resistência à penicilina, ampicilina, quinupristina-dalfopristina, linezolida e vancomicina. Entre as cepas, 96,8 por cento, 98,3 por cento, 46,8 por cento e 29,0 por cento foram sensíveis à rifampicina, nitrofurantoína, trimetoprim-sulfametoxazol e tetraciclina, respectivamente. Para as quinolonas, a ordem de sensibilidade foi: gatifloxacina (98,4 por cento) > levofloxacina (93,8 por cento) > ciprofloxacina (64,5 por cento). A taxa de resistência à eritromicina (9,7 por cento) foi superior a de outros relatos na Argentina. Nenhuma das cepas apresentou alto nível de resistência à gentamicina. Devido a 50 por cento das cepas de GBS terem apresentado MIC para gentamicina igual ou inferior a 8 mg/ml, correspondente à concentração usada em um dos meios seletivos recomendados para GBS, sugeriu-se ao menos em nossa população, o emprego de ácido nalidíxico e colistina em meios seletivos para melhorar a sensibilidade da triagem de culturas para GBS em mulheres grávidas.

Enteropatógenos en la diarrea infantil de la ciudad de Posadas, Misiones / Children's diarrhoea enteropathogens in Posadas, Misiones

El presente trabajo informa los resultados del aislamiento, frecuencia y distribución de enteropatógenos en niños menores de cinco años, sin tratamiento antibiótico previo, con menos de siete días de evolución del cuadro de diarrea, ambulatorios e internados en el hospital "Dr. Ramón Madariaga" de Posadas, Misiones, entre junio de 1986 y diciembre de 1990. Del total de 1127 niños con diarrea el 70 ciento por ciento requirió internación. El mayor número de casos de diarrea se registró durante la primavera y el verano, en niños de 1 a 11 meses de edad. La distribución proporcional de los principales enteropatógenos fue Escherichia coli enteropatógeno (EPEC) (27 por ciento), parásitos (23,7 por ciento), Escherichia coli enterotoxigénico (ETEC) (17 por ciento), Shigella (14,5 por ciento) y rotavirus (11,6 por ciento). La mayor incidencia de rotavirus se registró en los meses más fríos, en cambio Shigella, ETEC, Salmonella y parásitos en los meses cálidos. Los niños más afectados fueron los de 1 a 11 meses de edad, con mayor incidencia de EPEC, ETEC, Salmonella y rotavirus. Los parásitos fueron aislados con mayor frecuencia en niños mayores. Shigella tuvo un comportamiento independiente de la edad. Cryptosporidium, causal de diarrea severa, fue aislado en el 3,2 por ciento de los casos