Emergence of extended-spectrum Beta-lactamase producing Enterobacter spp. in patients with bacteremia in a tertiary hospital in southern Brazil

BACKGROUND: Extended-spectrum β-lactamases (ESBLs) are increasingly prevalent in Enterobacter spp., posing a challenge to the treatment of infections caused by this microorganism. The purpose of this retrospective study was to evaluate the prevalence, risk factors, and clinical outcomes of inpatients with bacteremia caused by ESBL and non ESBL-producing Enterobacter spp. in a tertiary hospital over the period 2004-2008.MethodsThe presence of blaCTX-M, blaTEM, blaSHV, and blaPER genes was detected by polymerase chain reaction (PCR) and nucleotide sequence analysis. Genetic similarity between strains was defined by pulsed-field gel electrophoresis (PFGE).Results Enterobacter spp. was identified in 205 of 4907 of the patients who had positive blood cultures during hospitalization. Of those cases, 41 (20%) were ESBL-producing Enterobacter spp. Nosocomial pneumonia was the main source of bacteremia caused by ESBL-producing Enterobacter spp. The presence of this microorganism was associated with longer hospital stays. The ESBL genes detected were: CTX-M-2 (23), CTX-M-59 (10), CTX-M-15 (1), SHV-12 (5), and PER-2 (2). While Enterobacter aerogenes strains showed mainly a clonal profile, Enterobacter cloacae strains were polyclonal. Conclusion Although no difference in clinical outcomes was observed between patients with infections by ESBL-producing and non-ESBL-producing strains, the detection of ESBL in Enterobacter spp. resulted in the change of antimicrobials in 75% of cases, having important implications in the decision-making regarding adequate antimicrobial therapy

ANTECEDENTES: Las -lactamasas de espectro extendido (BLEE) son cada vez más frecuentes en Enterobacter spp., lo que representa un desafío para el tratamiento de infecciones causadas por este microorganismo. El propósito de este estudio fue evaluar los factores de riesgo y los resultados clínicos de pacientes ingresados con bacteriemia causada por Enterobacter spp. productores de BLEE en un hospital terciario durante los años 2004-2008. MÉTODOS: La presencia de los genes blaCTX-M, blaTEM, blaSHV, e blaPER se detectó mediante la reacción en cadena de la polimerasa (PCR) y análisis de la secuencia de nucleótidos. La similitud genética entre las cepas fue definida por electroforesis en gel de campo pulsado (PFGE). RESULTADOS: Enterobacter spp. fue identificado en 205 pacientes de un total de 4.907 que tenían cultivos positivos de sangre durante la hospitalización. De esos 205 casos, 41 (20%) eran Enterobacter spp. productores de BLEE. La neumonía nosocomial fue la principal fuente de bacteriemia causada por Enterobacter spp. productores de BLEE. La presencia de este microorganismo se asoció con una mayor estancia hospitalaria. Las BLEE detectadas fueron: CTX-M-2 (23), CTX-M-59 (10), CTX-M-15 (1), SHV-12 (5) y PER-2 (2). Mientras que las cepas de Enterobacter aerogenes presentaron un perfil principalmente clonal, E. cloacae fueron policlonales. CONCLUSIONES: Si bien no fueron observadas diferencias en los resultados clínicos entre los pacientes con infecciones causadas por cepas productoras de BLEE y no productoras de BLEE, la detección de BLEE en Enterobacter spp., resultó en el cambio de los antimicrobianos en el 75% de los casos, habiendo implicaciones importantes en la toma de las decisiones con respecto a la terapia antimicrobiana adecuada

Emergence of extended-spectrum ß-lactamase producing Enterobacter spp. in patients with bacteremia in a tertiary hospital in southern Brazil.

BACKGROUND: Extended-spectrum ß-lactamases (ESBLs) are increasingly prevalent in Enterobacter spp., posing a challenge to the treatment of infections caused by this microorganism. The purpose of this retrospective study was to evaluate the prevalence, risk factors, and clinical outcomes of inpatients with bacteremia caused by ESBL and non ESBL-producing Enterobacter spp. in a tertiary hospital over the period 2004-2008. METHODS: The presence of blaCTX-M, blaTEM, blaSHV, and blaPER genes was detected by polymerase chain reaction (PCR) and nucleotide sequence analysis. Genetic similarity between strains was defined by pulsed-field gel electrophoresis (PFGE). RESULTS: Enterobacter spp. was identified in 205 of 4907 of the patients who had positive blood cultures during hospitalization. Of those cases, 41 (20%) were ESBL-producing Enterobacter spp. Nosocomial pneumonia was the main source of bacteremia caused by ESBL-producing Enterobacter spp. The presence of this microorganism was associated with longer hospital stays. The ESBL genes detected were: CTX-M-2 (23), CTX-M-59 (10), CTX-M-15 (1), SHV-12 (5), and PER-2 (2). While Enterobacter aerogenes strains showed mainly a clonal profile, Enterobacter cloacae strains were polyclonal. CONCLUSION: Although no difference in clinical outcomes was observed between patients with infections by ESBL-producing and non-ESBL-producing strains, the detection of ESBL in Enterobacter spp. resulted in the change of antimicrobials in 75% of cases, having important implications in the decision-making regarding adequate antimicrobial therapy.