Abstract
BackgroundExtended-spectrum β-lactamases (ESBLs) in Gram-negative organisms is now a major concern in Enterobacteriaceae worldwide. This study determined a point-prevalence and genetic profiles of ESBL-producing isolates among members of the family Enterobacteriaceae in Lagos State University Teaching Hospital Ikeja, Nigeria.MethodsConsecutive non-repetitive invasive multidrug-resistant isolates of the family Enterobacteriaceae obtained over a period of 1 month (October 2011) were studied. The isolates were identified using VITEK-2/VITEK MS Systems. Susceptibility testing was performed using E test technique; results were interpreted according to the criteria recommended by the Clinical and Laboratory Standards Institute (CLSI, 2012). ESBL production was detected by E test ESBL method and confirmed by polymerase chain reaction (PCR).ResultsDuring the one-month study period, 38 isolates with ESBL phenotypic characteristics were identified and confirmed by PCR. Of these, 21 (55.3 %) were E. coli, 12 (31.6 %) K. pneumoniae, 3 (7.9 %) Proteus spp., 1 (2.6 %) each M. morganii and C. freundii. Thirty (79 %) harbored blaCTX-M genes. Sequence analysis revealed that they were all blaCTX-M-15 genes. Twenty-nine (96.7 %) of these, also harbored blaTEM genes simultaneously. All the CTX-M-15-producing isolates carried insertion sequence blaISEcP1 upstream of blaCTX-M-15 genes. The E. coli isolates were genetically heterogeneous, while the K. pneumoniae had 98 % homology.ConclusionsOur point-prevalence surveillance study revealed a high prevalence of Enterobacteriaceae isolates harboring blaCTX-M-15 in the Hospital. Urgent implementation of antibiotic stewardship and other preventive strategies are necessary at this time in our hospital.
Highlights
Extended-spectrum β-lactamases (ESBLs) in Gram-negative organisms is a major concern in Enterobacteriaceae worldwide
Genotyping of isolates Fifteen randomly selected strains of the blaCTX-M-15positive isolates (9 E. coli and 6 K. pneumoniae) were investigated for genetic relatedness using pulsed-field gel electrophoresis (PFGE) with Xba1 digestion of the genomic DNA separated by electrophoresis in 1.2 % agarose gel [26] and the strains compared by differences in number and mobility of the bands. During this one month study, a total of 73 isolates belonging to the family Enterobacteriaceae were studied
The predominant genotype of the Extended spectrum beta-lactamases (ESBLs) found in the clinical isolates of Enterobacteriaceae in this study was blaCTX-M-type genes with all being blaCTX-M-15; over 96 % of these 38 isolates harbored a blaTEM β-lactamase gene
Summary
Extended-spectrum β-lactamases (ESBLs) in Gram-negative organisms is a major concern in Enterobacteriaceae worldwide. Gram-negative organisms belonging to the family Enterobacteriacae commonly produce beta-lactamases, which confer resistance to most penicillins but not to expanded-spectrum cephalosporins. The genes encoding these beta-lactamases are plasmid-borne, and belong to the TEM-1, TEM-2, and SHV-1 types [1]. In Enterobacteriaceae, resistance to cephalosporin is commonly due to production of extended-spectrum β-lactamases (ESBLs). Most ESBLs are derivatives of TEM and SHV β-lactamase families Other groups such as PER and CTX-M types have been described [8, 9]. Other β-lactamases, including those belonging to Ambler class B (metallo-β-lactamase), class A (e.g. KPC) or class D (OXA-48), capable of hydrolyzing carbapenems have emerged [10,11,12]
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