Extended-spectrum beta-lactamase-producing Klebsiella spp. in a

Jun 22, 2007 - Pessoa-Silva CL, Meurer Moreira B, Camara Almeida V,. Flannery B, Almeida Lins MC, Mello Sampaio JL, Martins. Teixeira L, Vaz Miranda LE, ...
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Eur J Clin Microbiol Infect Dis (2007) 26:563–570 DOI 10.1007/s10096-007-0338-9

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Extended-spectrum beta-lactamase-producing Klebsiella spp. in a neonatal intensive care unit: risk factors for the infection and the dynamics of the molecular epidemiology K. Kristóf & D. Szabó & J. W. Marsh & V. Cser & L. Janik & F. Rozgonyi & A. Nobilis & K. Nagy & D. L. Paterson

Published online: 22 June 2007 # Springer-Verlag 2007

Abstract The extended-spectrum beta-lactamase (ESBL)producing Klebsiella spp. cause worldwide problems in intensive care units. The aim of this study was to investigate the molecular epidemiology of ESBL-producing Klebsiella pneumoniae and K. oxytoca strains in a neonatal intensive care unit (NICU) in Budapest, Hungary and to determine the risk factors of the infections and the epidemiological features. Infections with Klebsiella spp. were analyzed retrospectively by reviewing the medical records between January 2001 and December 2005. Antibiotic susceptibility tests, isoelectric focusing, pulsed field gel electrophoresis, plasmid analysis, PCR for blaTEM and blaSHV and DNA sequencing analysis were performed on ESBL-producing K. Kristóf and D. Szabó equally contributed to this work. K. Kristóf : D. Szabó (*) : V. Cser : F. Rozgonyi : K. Nagy Institute of Medical Microbiology, Semmelweis University, Nagyvárad tér 4, 1089 Budapest, Hungary e-mail: [email protected] J. W. Marsh : D. L. Paterson Division of Infectious Diseases, University of Pittsburgh Medical Center, Suite 3A Falk Medical Building, 3601 5th Avenue, Pittsburgh, PA 15213, USA

Klebsiella isolates. A total of 45 babies were found to be infected with non-ESBL-producing Klebsiella spp. and 39 with ESBL-producing Klebsiella spp. Of the parameters analyzed, including sex, gestational age, twin pregnancy, birth weight, presence of central vascular catheter, mechanical ventilator use, parenteral nutrition, polymicrobial infection, caesarean section, transfusion and mortality, we found no statistically significant difference between the ESBL and the non-ESBL groups, or between the K. pneumoniae and K. oxytoca species. Further characterization of the ESBLproducing K. pneumoniae and K. oxytoca strains isolated between February 2001 and January 2003 revealed three distinct PFGE patterns of SHV-5-producing K. pneumoniae (A, B, E) and two distinct patterns of SHV-12-producing K. oxytoca (C,D) isolates; these had different plasmid profiles. From July to November 2005, a new SHV-5 producing K. oxytoca (F) was isolated. The molecular epidemiology of ESBL-producing organisms in a NICU over time shows substantial shifts in predominant strains. The ESBL production of the infected organisms has an impact on the survival of newborn babies with infections caused by Klebsiella spp.

Introduction L. Janik Institute of Public Health, Semmelweis University, Nagyvárad tér 4, 1089 Budapest, Hungary A. Nobilis Second Department of Obstetrics and Gynecology, Semmelweis University, 1082 Üllői út 78/A, Budapest, Hungary

Klebsiella spp. have long been known to be prominent causes of infection in neonatal intensive care units (NICUs) [1]. The organisms can survive in the environment and also, transiently, on the hands of health care workers [2–4], which facilitates baby-to-baby transmission in the NICU. Since the commercial introduction of extended-spectrum cephalosporins, extended-spectrum beta-lactamase (ESBL)-

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producing strains of Klebsiella have posed a particularly serious problem worldwide [1, 5]. Many ESBLs are derivatives of TEM-1, TEM-2 or SHV-1. Mutations in the genes encoding TEM-1, TEM-2 or SHV-1 have extended the substrate specificity of the beta-lactamases to include some extended-spectrum cephalosporins and aztreonam [1]. This creates considerable difficulty when empiric antibiotic therapy is needed for seriously ill neonates. While the clinical microbiology laboratories of some hospitals have access to molecular epidemiologic tools, such as pulsed field gel electrophoresis (PFGE), most laboratories have no access to such resources. Thus, the dynamics of infection with Klebsiella isolates in certain hospital units, such as NICUs, may be completely unknown. As clinical isolates of the family Enterobacteriaceae had been collected in our institute, we analyzed these for the production of ESBLs and investigated the clinical characteristics of infections caused by ESBL-producing and non-ESBL-producing Klebsiella isolates. This report describes the molecular epidemiology of infections with Klebsiella spp. occurring in a NICU in Hungary. We performed a follow-up molecular epidemiologic survey during a 5-year period to determine the dynamics of the molecular epidemiology of ESBL-producing Klebsiella spp. in the same NICU. At the same time, we determined the risk factors and mortality associated with ESBLproducing Klebsiella spp. by reviewing the medical records retrospectively.

Materials and methods Patients and bacterial strains The Klesbiella spp. were isolated from clinical samples of newborn babies admitted to the NICU of the Second Department of Obstetrics and Gynecology of Semmelweis University between January 2001 and December 2006. Environmental screening was carried out regularly each year using swabs moistened with sterile saline and included work surfaces, sinks, incubators, solutions and equipment used in intubation and in enteral feeding. The identification of species was according to the API 20E system (BioMerieux, Marcy-l'Etoile, France). Escherichia coli ATCC 25922 was used as an ESBL-negative reference strain, and K. pneumoniae ATCC 700603 was used as an ESBL-positive reference strain.

Eur J Clin Microbiol Infect Dis (2007) 26:563–570

cerebrospinal fluid, bronchoalveolar lavage and/or aseptically obtained any other physiological body fluid [6]. Klebsiella spp. colonization was defined as the isolation of Klebsiella spp. from a patient without clinical symptoms or signs of infection. Review of medical records Infections with Klebsiella spp. were analyzed retrospectively by reviewing the medical records. The demographic and clinical data collected for each neonate included the mode of delivery, singleton or twin pregnancy, sex, age, birth weight, acquisition of polymicrobial infection, use of a mechanical ventilator and the final outcome of the infection. Ampicillin + gentamicin was used for empiric therapy in all clinical cases; this was switched for meropenem therapy if ESBL-production had been confirmed. Statistical analysis The chi-square analysis was used to compare proportions, P values