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.

[Class 1 integrons among Salmonella enterica isolates producing different types of beta-lactamases from the health region of Tortosa (Spain)]. / Integrones de clase 1 en aislados de Salmonella enterica productores de diferentes tipos de betalactamasas recogidos en la región sanitaria de Tortosa.

OBJECTIVE: To assess the frequency of class 1 integrons among isolates of Salmonella enterica producing different types of beta-lactamases from the health region of Tortosa, and to attempt to establish the resistance genes located within their variable regions. METHODS: The presence of class 1 integrons and of aadA1, aadA2, dfrA1, tem-1, oxa-1 and pse-1 resistance genes within their variable regions was investigated by PCR in 100 ampicillin-resistant isolates of S. enterica (30 S. enteritidis, 56 S. Typhimurium and 14 from other serotypes) consecutively recovered in our laboratory between 2000 and 2001. Beta-lactamases were characterized by isoelectric focusing and PCR. RESULTS: a) 6/57 TEM-1 producing isolates carried integrons: 1 S. ser Panama, 2 S. ser Enteritidis and 1 S. ser Typhimurium (1600 pb/aadA1-dfrA1); 1 S. ser Panama (1600 pb/aadA2-dfrA1); 1 S. ser Grumpensis (1500 pb 1 1700 pb; aadA2 and ??) b) All OXA-1 producing isolates (20 S. ser Typhimurium) bore an integron of 2000 pb/aadA1-oxa-1; c) All PSE-1 producing isolates (22 S. ser Typhimurium, most of them 104 phage type, and 1 S. enterica immobile [4,12:-:-]) harbored 2 integrons (1000 pb/aadA1 and 1,00 pb/pse-1). CONCLUSION: The presence of class 1 integrons carrying oxa-1 or pse-1 resistance genes in all the OXA-1-producing and PSE-1-producing isolates investigated could have contributed to their spread and explain the increase in frequency of multiresistant S. ser Typhimurium isolates harboring these enzymes seen in the health region of Tortosa. In addition, we report the first isolate of S. ser enterica serotype Grumpensis harboring integrons.

Integrones de clase 1 en aislados de Salmonella enterica productores de diferentes tipos de betalactamasas recogidos en la región sanitaria de Tortosa / Class 1 integrons among Salmonella enterica isolates producing different types of beta-lactamases from the health region of Tortosa (Spain)

Objetivo. Estudiar la frecuencia de integrones de clase 1 en aislados de Salmonella enterica productores de diferentes tipos de betalactamasas recogidos en la región sanitaria de Tortosa e intentar determinar los genes de resistencia que llevan insertados. Métodos. Se investigó mediante reacción en cadena de la polimerasa (PCR) la presencia de integrones de clase 1 y de los genes aadA1, aadA2, dfrA1, tem-1, oxa-1 y pse-1 en la región variable de éstos, en 100 aislados de S. enterica (30 S. enteritidis, 56 S. ser Typhimurium y 14 de otros serotipos) resistentes a ampicilina recuperados consecutivamente en nuestro laboratorio entre 2000 y 2001. Las betalactamasas se caracterizaron por isoelectroenfoque y PCR. Resultados. a) 6/57 aislados productores de TEM-1 presentaban integrones: 1 S. ser Panama, 2 S. ser Enteritidis y 1 S. ser Typhimurium (1.600 pb/aadA1-dfrA1); 1 S. ser Panama (1.600 pb/aadA2-dfrA1); 1 S. ser Grumpensis (1.500 pb 1 1.700 pb; aadA2 y ??); b) todos los aislados productores de OXA-1 (20 S. ser Typhimurium) transportaban un integrón de 2.000 pb/aadA1-oxa-1. c) todos los aislados productores de PSE-1 (22 S. ser Typhimurium, la mayoría fagotipo 104, y 1 S. enterica inmóvil [4,12:-:-]) contenían 2 integrones (1.000 pb/aadA1 y 1.200 pb/pse-1). Conclusión. La presencia de integrones que transportaban los genes oxa-1 o pse-1 en todos los aislados estudiados productores de OXA-1 y PSE-1 podría haber facilitado su diseminación y explicar el incremento de aislados multirresistentes de S. ser Typhimurium portadores de estas enzimas en la región sanitaria de Tortosa. Se describe, asimismo, por primera vez la presencia de integrones en un aislado del serotipo Grumpensis (AU)

Objective. To assess the frequency of class 1 integrons among isolates of Salmonella enterica producing different types of beta-lactamases from the health region of Tortosa, and to attempt to establish the resistance genes located within their variable regions. Methods. The presence of class 1 integrons and of aadA1, aadA2, dfrA1, tem-1, oxa-1 and pse-1 resistance genes within their variable regions was investigated by PCR in 100 ampicillin-resistant isolates of S. enterica (30 S. enteritidis, 56 S. Typhimurium and 14 from other serotypes) consecutively recovered in our laboratory between 2000 and 2001. Beta-lactamases were characterized by isoelectric focusing and PCR. Results. a) 6/57 TEM-1 producing isolates carried integrons: 1 S. ser Panama, 2 S. ser Enteritidis and 1 S. ser Typhimurium (1600 pb/aadA1-dfrA1); 1 S. ser Panama (1600 pb/aadA2-dfrA1); 1 S. ser Grumpensis (1500 pb 1 1700 pb; aadA2 and ??) b) All OXA-1 producing isolates (20 S. ser Typhimurium) bore an integron of 2000 pb/aadA1-oxa-1; c) All PSE-1 producing isolates (22 S. ser Typhimurium, most of them 104 phage type, and 1 S. enterica immobile [4,12:-:-]) harbored 2 integrons (1000 pb/aadA1 and 1,00 pb/pse-1). Conclusion. The presence of class 1 integrons carrying oxa-1 or pse-1 resistance genes in all the OXA-1-producing and PSE-1-producing isolates investigated could have contributed to their spread and explain the increase in frequency of multiresistant S. ser Typhimurium isolates harboring these enzymes seen in the health region of Tortosa. In addition, we report the first isolate of S. ser enterica serotype Grumpensis harboring integrons (AU)