Molecular Characterization of Extended-Spectrum Beta-Lactamases in Escherichia coli and Klebsiella pneumoniae in Accra, Ghana

Abstract

Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta lactamases that are capable of hydrolysing beta-lactams except carbapenems and cephamycins. The ESBL types include SHV, TEM and CTX-M, OXA, PER and VEB-1. The most common ones isolated from clinical specimen are the CTX-M, SHV and TEM.  The specific ESBL-producing organisms have different genetic characteristics which mark their identification at the molecular level. This work sought to determine the genetic characterization of ESBL-producing K. pneumoniae and E. coli in Accra. The molecular investigations of the ESBL-coding genes included extraction of 100 DNA templates of phenotypic ESBL-producing isolates by boiling method, preparation of the PCR reaction mixture using appropriate primers, standard PCR reaction in a thermocycler,   agarose gel electrophoresis, bands visualization by ultraviolet trans-illumination and bands photography using a Kodak EDAS 290 gel documentation system. The results significantly (p<0.05) indicated that of the 100 ESBL producers, 90(90%) possess CTX-M genes and 25(25%) had TEM genes. None of the ESBL producers possesses SHV genes. Seventy (70%) of the ESBL producers possess only CTX-M genes and 5(5%) had only TEM genes. Twenty (20%) of the isolates had both CTX-M and TEM genes. Of the 100 ESBL phenotypes, 78(78%) and 2(2%) were positive for CTX-M-1group and CTX-M-9group ESBL genes respectively. Organisms producing CTX-M-type ESBL are more prevalent in Accra than other ESBL types. CTX-M-1group producing isolates dominated the ESBL phenotypes with CTX-M-15 likely to be the dominate CTX-M-type ESBL. There is the need for further studies into the characteristic transmission, pathogenesis, antibiotic resistance expression, and infection control of CTX-M-type ESBL and TEM-type ESBL in Accra.

Keywords: Extended spectrum beta-lactamase, CTX-M genes, TEM genes, SHV genes, Molecular