First reported nosocomial outbreak of Serratia marcescens harboring bla IMP-4 and bla VIM-2 in a neonatal intensive care unit in Cairo, Egypt.

Abstract

IntroductionSerratia marcescens is a significant hospital-acquired pathogen, and many outbreaks of S. marcescens infection have been reported in neonates. We report a sudden breakout of S. marcescens harboring the blaIMP-4 and blaVIM-2 metallo-β-lactamase (MBL) genes that occurred from March to August 2015 in the neonatal intensive care unit of Cairo University Hospital, Cairo, Egypt.MethodsDuring the study period, 40 nonduplicate clinical isolates of S. marcescens were collected from blood culture samples. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was used to identify each isolate. Then, minimum inhibitory concentrations of different antibiotics were assessed by the Vitek 2 compact system. Screening of the MBL genes blaIMP, blaVIM, blaSIM-1, blaSPM-1, and blaGIM-1 as well as the carbapenemase genes KPC, NDM, OXA-48, SME-1, and SME-2 were evaluated. Pulsed field gel electrophoresis was preformed to detect the genetic relationship of the isolates.ResultsAnalysis showed that 37.5% of the S. marcescens clinical isolates were resistant to meropenem (minimum inhibitory concentrations ≥ 2 µg/mL), and blaIMP-4 and blaVIM-2 were the most prevalent MBL genes (42.5% and 37.5%, respectively). None of the other investigated genes were observed. Pulsed field gel electrophoresis typing revealed two discrete clones; 33/40 (82.5%) were pulsotype A and 7/40 (17.5%) were pulsotype B.ConclusionHere, we report for the first time the detection of MBL-producing S. marcescens isolates, particularly IMP-4 and VIM-2 recovered from inpatients with bacteremias from the intensive care unit at Cairo University Hospital.