Molecular determinants of ß-lactamase producing Klebsiella pneumoniae in Mansoura

Background: The emergence of s-lactamase- producing Klebsiella pneumonia, represents a significant diagnostic and therapeutic challenge to the management of infections caused by this organism. This prospective study aimed to study the frequency of s-lactamase production by K. pneumoniae in neonatal intensive care unit (NICU) of Mansoura University Children’s Hospital in Egypt. Methods: This study was conducted over a period of 36 months from September 2010 to August 2013, where 684 samples were collected from different body sites of neonates in the NICU. Microbial isolation, identification and antimicrobial susceptibility testing were carried out. s-lactamase production by K. pneumoniae isolates was confirmed by phenotypic methods and PCR amplification of related genes using a sixgene panel for the amplification of the bla CMY-2 , bla DHA , bla ACC , bla SHV, bla TEM and bla CTX-M genes. In vitro transformation and conjugation were carried out to detect plasmid mediated AmpC s- lactamase resistance by transmission to E. coli. Results: K. pneumoniae was isolated at a rate of 12.6% and s-lactamase production was detected in 62.8% of the isolates. The most commonly detected s-lactamase gene was bla SHV (51.9%), followed by Bla CMY-2 (16.7%), bla DHA (13%), bla TEM (9.2%), bla CTX-M (7.4%) and bla ACC (1.9%). Additionally, some strains carried combinations of two or three genes. The plasmid carrying bla CMY-2 was 100% successfully transformed