MOLECULAR TYPING OF ESBL-PRODUCING KLEBSIELLA PNEUMONIAE ISOLATES DURING THREE OUTBREAKS IN NEONATAL INTENSIVE CARE UNITS

Nadya Rakovitsky 1,2 Jonathan Lellouche 1,2 David Schwartz 1,2 Alon Samet 1,2 Rachel Hamias 1,2 Ester Solter 1,2 Mitchell Schwaber 2 Yehuda Carmeli 1,2
1Ministry of Health, National Laboratory for Antibiotic Resistance and Investigation of Outbreaks in Medical Institutions, Tel Aviv, Israel
2Ministry of Health, National Institute for Antibiotic Resistance and Infection Control, Tel Aviv, Israel

INTRODUCTION

  1. pneumoniae has emerged as an important pathogen linked to outbreaks in neonatal intensive care units (NICUs), usually involving strains expressing extended-spectrum β-lactamases (ESBLs). We investigated the molecular mechanism of ß-lactam resistance in ESBL-producing K. pneumoniae (ESBL-KP) strains isolated during three different outbreaks in the neonatal intensive care units (NICUs) of tertiary hospitals: "A" (500 beds), "B" (1000 beds), and "C" (200 beds).

MATERIAL AND METHODS:

Bacterial isolates. A total of 56 isolates were collected during 2017 in three hospitals in the center of Israel. All suspected isolates were grown on selective CHROMagarTM ESBL and MacConkey agar plates and identified to the species level by VITEK® MS. Antibiotic susceptibility was determined by VITEK® 2.

ESBL phenotype confirmation. ESBL phenotype was confirmed by double disc diffusion according to CLSI procedures.

Molecular typing. Isolates were characterized by BOX-PCR. To determine phylogenetic relatedness, we compared the electropherograms, generated dendrograms, and performed cluster analysis.

Detection of ESBL genes. Molecular identification of resistance mechanisms was performed by PCR using appropriate primers for the detection of blaSHV, blaTEM, and blaCTX-M.

RESULTS

ESBL phenotypes were confirmed for the all 56 isolates. Molecular typing reveals one major clone in each outbreak and additional unrelated clones and isolates. The typing was also revealed in hospital "A" that there were mother-baby pairs who shared the same clone. The pairs with different clones demonstrate that other sources played a role in transmission. DNA sequence analysis showed that 53 (53/56) isolates harbored bla CTX-M-15, 51 (51/56) blaSHV and 13 of them a SHV-2 variant. TEM-1 variant was found in 11 (11/56) isolates. Preliminary results shows plasmid-mediated resistance involved in these outbreaks. Further investigation is needed to determine if horizontal gene transfer occurred between clones and clarify the relationship between the outbreaks.









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