Antibióticos y expresión de betalactamasas de espectro extendido (BLEE) en agentes bacterémicos / Use of antibiotics and expression of extended spectrum betalactamases (ESBL) in bacteremic agents

Objective: To evaluate the association between Escherischia Coli (E. Coli) and Klebsiella spp bacteremia, both of which produce Extended Spectrum beta-lactamases (ESBL), and the use of third generation cephalos-porines (TGC) during 30 days prior to the development of the infection. Patients and Methods: Case study of all patients hospitalized between 2004 and 2007 at Hospital de Niños Roberto del Río, who presented E. coli y Klebsiella spp bacteremia. Results: 212 episodes of E. coli o Klebsiella spp bacteremias were found; 205 contained all necessary data, 47 of which were cases and 158 were controls. The use of TGC showed a statistically significant correlation with the finding of ESBL in those patients' bacteremias (OR 2,5; IC95 percent 1,26-5). In addition, an independent statistically significant association was found with hospital acquired infections (OR 8,2; IC95 percent 2,7-27,1), and the use of Central Venous Catheter (OR 38,9; IC95 percent 14,3-106,0) became close to statistical significance. Conclusions: This study shows a statistically significant association between ESBL bacteremias and use of TGC within 30 days prior to the infection, confirming other literature reports.

Objetivo: Estudiar la asociación entre bacteriemia por E. coli y Klebsiella spp productoras de beta-lactamasas de espectro extendido (BLEE) y el uso de cefalosporinas de tercera generación (CTG) durante los 30 días previos al desarrollo de la infección. Método: Estudio caso control encestado desarrollado entre los años 2004 y 2007 en el Hospital de Niños Roberto del Río, con análisis retrospectivo de los pacientes con bacteriemias por E. coli y Klebsiella spp. Resultados: Se registraron 212 episodios de bacteriemias por E. coli o Klebsiella spp, en 205 de ellos se contó con los registros necesarios, 47 fueron casos y 158 controles. El uso de CTG se asoció de modo estadísticamente significativo con la probabilidad de aislar cepas BLEE de bacteriemias en estos pacientes (OR 2,5; IC95 por ciento 1,26-5). Además, se observó asociación independiente y estadísticamente significativa con Infección Intrahospitalaria (OR 8,2; IC95 por ciento 2,7-27,1), y el uso de Catéter Venoso Central (OR 38,9; IC95 por ciento 14,3-106,0) se acercó a la significancia estadística. Conclusiones: Nuestro trabajo establece la asociación estadística entre bacteriemia por cepas BLEE y el uso de CTG dentro de los 30 días previos al desarrollo de la infección, confirmando lo sugerido por la literatura.

Recomendaciones para el análisis de datos acumulados de susceptibilidad antimicrobiana en instituciones de salud / Recommendations for the analysis of cumulated data in antimicrobial susceptibility in health institutions

Due to the great variability in antimicrobial resistance patterns, local reports of cumulative antimicrobial susceptibility data are necessary in every health center. The purpose is to guide clinical decisions and the early detection of patterns that allow preventive measures to avoid dissemination of resistant strains. The main objective of this guide is to provide recommendations for the analysis of antimicrobial susceptibility data and elaboration of a local report. Recommendations provided in this guide are based on the Clinical and Laboratory Standards Institute (CLSI) document "Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data" (3). Key aspects related to information gathering and data processing, analysis and presentation are described.

Considerando la gran variabilidad en la distribución de la resistencia microbiana, es una necesidad que cada centro de salud genere reportes locales de datos acumulados de susceptibilidad, con el propósito de guiar las decisiones clínicas y detectar tendencias que permitan establecer medidas de prevención para evitar la diseminación de cepas resistentes. Esta guía tiene como objetivo entregar recomendaciones para el análisis de susceptibilidad antimicrobiana y aportar datos útiles para la elaboración del informe local. Las recomendaciones que contenidas em este documento están basadas en el documento "Analysis and Presentation of Cumulative Antimicrobial Susceptibility Test Data de Clinical and Laboratory Standards Institute (CLSI) (3). Se describen aspectos claves relacionados con los requerimientos de la información, el procesamiento de los datos, el análisis y presentación de éstos.

Epidemiología clínica y molecular de las infecciones por Shigella spp en niños de la Región Metropolitana durante el verano 2004-2005 / Shigella spp Infections In children living In the Metropolitan RegionChile, during summer of 2004-2005

Background: Shigella spp is a frequent cause of diarrhea in children. Antimicrobials decrease the duration of diarrhea and pathogen excretion. However, the increasing resistance limits their therapeutic value. Aim: To study Shigella serotype distribution in the Metropolitan Region in Chile, and its relationship with severity of disease, antimicrobial resistance pattern and clonality. Material and methods: During summer 2004-2005, stool samples from children with diarrhea were collected in Cary Blair transpon medium and cultured. Shigella isolates were serotyped using monoclonal and polyclonal commercial antibodies. In vitro activity of ampicillin, amoxicillin/clavulanic acid, chloramphenicol, cotrimoxazol, nalidixic acid, ciprofloxacin, ceftriaxone and azythromycin was determined by minimal inhibitory concentration (MIC). Clonality was studied by pulsed-field gel electrophoresis (PFGE) using Xbal as restriction enzyme. Results: One hundred thirty nine Shigella strains were isolated (77 S sonnei and 62 S flexneri). S sonnei and S flexneri 2a serotypes were responsible for 95 percent of episodes. Children aged 2-4 years, showed a greater incidence of Shigella infections and 77 percent of episodes were treated on an ambulatory basis. High resistance levels were observed for ampicillin, cotrimoxazole, amoxicillin-clavulanic acid and chloramphenicol (67 percent, 60 percent, 56 percent and 45 percent, respectively). We found 11 resistance patterns and 61,2 percent of strains were multiresistant. There were multiple clones without a strict relationship with resistance patterns. Conclusions: Shigella infections in Metropolitan Region in Chile are associated to a restricted number of serotypes, representing a clonal expansion associated to different antimicrobial resistant patterns.

[Shigella spp infections in children living in the Metropolitan Region, Chile, during summer of 2004-2005]. / Epidemiología clínica y molecular de las infecciones por Shigella spp en niños de la Región Metropolitana durante el verano 2004-2005.

BACKGROUND: Shigella spp is a frequent cause of diarrhea in children. Antimicrobials decrease the duration of diarrhea and pathogen excretion. However, the increasing resistance limits their therapeutic value. AIM: To study Shigella serotype distribution in the Metropolitan Region in Chile, and its relationship with severity of disease, antimicrobial resistance pattern and clonality. MATERIAL AND METHODS: During summer 2004-2005, stool samples from children with diarrhea were collected in Cary Blair transpon medium and cultured. Shigella isolates were serotyped using monoclonal and polyclonal commercial antibodies. In vitro activity of ampicillin, amoxicillin/clavulanic acid, chloramphenicol, cotrimoxazol, nalidixic acid, ciprofloxacin, ceftriaxone and azythromycin was determined by minimal inhibitory concentration (MIC). Clonality was studied by pulsed-field gel electrophoresis (PFGE) using Xbal as restriction enzyme. RESULTS: One hundred thirty nine Shigella strains were isolated (77 S sonnei and 62 S flexneri). S sonnei and S flexneri 2a serotypes were responsible for 95% of episodes. Children aged 2-4 years, showed a greater incidence of Shigella infections and 77% of episodes were treated on an ambulatory basis. High resistance levels were observed for ampicillin, cotrimoxazole, amoxicillin-clavulanic acid and chloramphenicol (67%, 60%, 56% and 45%, respectively). We found 11 resistance patterns and 61,2% of strains were multiresistant. There were multiple clones without a strict relationship with resistance patterns. CONCLUSIONS: Shigella infections in Metropolitan Region in Chile are associated to a restricted number of serotypes, representing a clonal expansion associated to different antimicrobial resistant patterns.