Molecular epidemiology and resistance mechanisms involved in reduced susceptibility to amoxicillin/clavulanic acid in Klebsiella pneumoniae isolates from a chronic care centre.

The aim of this work was to investigate the molecular epidemiology and mechanisms responsible for reduced susceptibility to amoxicillin/clavulanic acid (AMC) amongst cefazolin-susceptible Klebsiella pneumoniae isolates from patients admitted to a chronic care institution. In total, 51 (29.8%) of 171 K. pneumoniae isolates recovered between 2006 and 2008 were non-susceptible to AMC, of which 45 were susceptible to cefazolin. Nucleotide sequencing analysis revealed that 19 produced IRT-11 and the remaining 26 were OXA-1-producers. All of the OXA-1-producing isolates harboured the aac(6')-Ib-cr-bla(OXA-1) cassette array, which in 23 isolates was located together with catB3 and arr3 within a class 1 integron and associated with qnrS2 (in 3 cases the integron lacked the qacEΔ1 and sul1 or sul3 genes). Genotyping analysis performed by enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) identified three different patterns amongst IRT-11-producing isolates (E1 to E3), with E1 being the most prevalent (63.2%), whilst the OXA-1-producing isolates were assigned to patterns E3 and E3a (isolates carrying typical class 1 integrons), E4 (isolates carrying defective integrons) and E5 (isolates without integrons). Genes encoding IRT-11 and OXA-1 were transferred by conjugation, and aac(6')-Ib-cr and qnrS2 were systematically co-transferred with bla(OXA-1). These results demonstrate that the high prevalence of decreased susceptibility to AMC amongst K. pneumoniae isolates from a chronic care hospital was mainly due to the simultaneous spread of two different clones, one of which comprised isolates producing IRT-11 and the other one comprised isolates that had acquired either the bla(OXA-1) gene located in a class 1 integron and linked to qnrS2 or the bla(IRT-11) gene.

Impacto de la investigación sistemática de estreptococo del grupo B en orina en la identificación de gestantes colonizadas / Effectiveness of systematic investigation for Group B Streptococcus in urine samples to identify colonized pregnant women

Objetivo Evaluar el impacto que tiene la investigación sistemática de estreptococo del grupo B (EGB) en orina en la identificación de gestantes colonizadas por este microorganismo. Métodos Se incluyó en el estudio a las 1.036 gestantes en las que durante el año 2006 se procesó algún urocultivo en el laboratorio de este hospital. Se identificó cualquier colonia en la que se sospechara EGB en todas las muestras de orina y en las muestras rectovaginales remitidas para cribado de colonización por EGB. Resultados Se aisló EGB en orina en 111 de las 1.036 gestantes (10,7%) y en 77 de estas el recuento fue inferior a 104 unidades formadoras de colonias/ml. Se recibieron muestras rectovaginales para cultivo de cribado de 841 de las 925 mujeres sin bacteriuria por EGB (10% resultado positivo) y muestras de 61 de las 111 mujeres con bacteriuria por EGB (60,7% con resultado positivo sin diferencias significativas al estratificar por recuento). La tasa estimada de colonización rectovaginal fue del 15,4% y la tasa de embarazadas con colonización detectable exclusivamente en orina fue del 4,2%. Sólo el 30% de las gestantes con bacteriuria positiva y cultivo de cribado negativo que recibieron atención en este hospital durante el parto recibió profilaxis antibiótica. Conclusiones La estrategia de incorporar la búsqueda exhaustiva de EGB en todas las muestras de orina de gestantes tiene un mayor rendimiento en la identificación de mujeres portadoras, y por tanto candidatas a recibir profilaxis durante el parto para prevenir la infección neonatal precoz, que la estrategia de realizar únicamente el cultivo de cribado rectovaginal al final del último trimestre de gestación (AU)

Objective To evaluate the effectiveness of systematic investigation for Group B Streptococcus (GBS) in urine samples to detect colonization in pregnant women. Methods This study included 1036 pregnant women whose urine samples were cultured in our laboratory during 2006. Any colony consistent with GBS was identified in urine or in rectovaginal samples submitted for screening of GBS colonization. Results GBS was recovered in urine samples from 111 of the 1036 women (10.7%), and in 77 of them bacterial count was <104 colony forming units/mL. Screening for GBS in rectovaginal samples was performed in 841 of the 925 pregnant women who did not have GBS bacteriuria (10.1% positive results) and in 61 of the 111 with GBS bacteriuria (60.7% positive results; no significant differences were found when results were stratified by colony count). Estimated rectovaginal colonization was 15.4%, and colonization exclusively detected in urine was 4.2%. Only 30% of pregnant women with GBS bacteriuria, but negative antenatal screening cultures who were admitted to our hospital for delivery received intrapartum antibiotic prophylaxis. Conclusions Systematic investigation of the presence of GBS in urine samples from pregnant women improves the detection of carriers who are candidates for receiving intrapartum prophylaxis to prevent perinatal GBS infection, when compared with rectovaginal screening culture in the last trimester of gestation alone (AU)

[Effectiveness of systematic investigation for Group B Streptococcus in urine samples to identify colonized pregnant women]. / Impacto de la investigación sistemática de estreptococo del grupo B en orina en la identificación de gestantes colonizadas.

OBJECTIVE: To evaluate the effectiveness of systematic investigation for Group B Streptococcus (GBS) in urine samples to detect colonization in pregnant women. METHODS: This study included 1036 pregnant women whose urine samples were cultured in our laboratory during 2006. Any colony consistent with GBS was identified in urine or in rectovaginal samples submitted for screening of GBS colonization. RESULTS: GBS was recovered in urine samples from 111 of the 1036 women (10.7%), and in 77 of them bacterial count was <10(4) colony forming units/mL. Screening for GBS in rectovaginal samples was performed in 841 of the 925 pregnant women who did not have GBS bacteriuria (10.1% positive results) and in 61 of the 111 with GBS bacteriuria (60.7% positive results; no significant differences were found when results were stratified by colony count). Estimated rectovaginal colonization was 15.4%, and colonization exclusively detected in urine was 4.2%. Only 30% of pregnant women with GBS bacteriuria, but negative antenatal screening cultures who were admitted to our hospital for delivery received intrapartum antibiotic prophylaxis. CONCLUSIONS: Systematic investigation of the presence of GBS in urine samples from pregnant women improves the detection of carriers who are candidates for receiving intrapartum prophylaxis to prevent perinatal GBS infection, when compared with rectovaginal screening culture in the last trimester of gestation alone.