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      CTX-M-15 is established in most multidrug-resistant uropathogenic Enterobacteriaceae and Pseudomonaceae from hospitals in Nigeria

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          β-Lactam antibiotics are widely used to treat urinary tract infections in Nigeria. This study aimed to determine the presence and characteristics of extended spectrum β-lactamases in commonly isolated uropathogenic Gram-negative bacteria (GNB) in Nigeria.

          Fifty non-duplicate GNB isolates consisting of Escherichia coli, 19; Klebsiella pneumoniae, 21; and Pseudomonas aeruginosa, 10 were obtained from three tertiary hospitals in Nigeria. The antibiotic susceptibility testing of all isolates to a panel of antibiotics including minimum inhibitory concentrations (MICs) and extended spectrum β-lactamases was determined. Polymerase chain reactions and sequencing were used to detect β-lactam genes.

          Polymerase chain reactions and sequencing identified varying extended spectrum β-lactamases (ESBLs) encoding genes for 24 isolates (48.0%). Cefotaximase-Munich (CTX-M) 15 was the dominant gene with 20/24 of the isolates positive at 83.3%; multiple genes (2 to 6 ESBL genes) were found in 20 of the isolates. The isolates encoded other genes such as CTX-M-14, 33.3%; sulfhydryl variable (SHV) variants, 58.3%; oxacillinase (OXA) variants, 70.8%; OXA-10, 29.2%; and Vietnamese extended β-lactamase (VEB) 1, 25.0%. There was no difference between the MIC 50 and MIC 90 of all the isolates.

          The high-level multidrug resistance of uropathogens to third generation cephalosporins including other antibiotics used in this study is strongly associated with carriage of ESBLs, predominantly CTX-M-15, as well as CTX-X-M-14, OXA-10, and VEB-1.

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          Most cited references 21

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          Extended-spectrum beta-lactamase-producing Enterobacteriaceae: an emerging public-health concern.

          The medical community relies on clinical expertise and published guidelines to assist physicians with choices in empirical therapy for system-based infectious syndromes, such as community-acquired pneumonia and urinary-tract infections (UTIs). From the late 1990s, multidrug-resistant Enterobacteriaceae (mostly Escherichia coli) that produce extended-spectrum beta lactamases (ESBLs), such as the CTX-M enzymes, have emerged within the community setting as an important cause of UTIs. Recent reports have also described ESBL-producing E coli as a cause of bloodstream infections associated with these community-onset UTIs. The carbapenems are widely regarded as the drugs of choice for the treatment of severe infections caused by ESBL-producing Enterobacteriaceae, although comparative clinical trials are scarce. Thus, more rapid diagnostic testing of ESBL-producing bacteria and the possible modification of guidelines for community-onset bacteraemia associated with UTIs are required.
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            Resistance plasmid families in Enterobacteriaceae.

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              Current Epidemiology and Growing Resistance of Gram-Negative Pathogens

              In the 1980s, Gram-negative pathogens appeared to have been beaten by oxyimino-cephalosporins, carbapenems, and fluoroquinolones. Yet these pathogens have fought back, aided by their membrane organization, which promotes the exclusion and efflux of antibiotics, and by a remarkable propensity to recruit, transfer, and modify the expression of resistance genes, including those for extended-spectrum β-lactamases (ESBLs), carbapenemases, aminoglycoside-blocking 16S rRNA methylases, and even a quinolone-modifying variant of an aminoglycoside-modifying enzyme. Gram-negative isolates -both fermenters and non-fermenters-susceptible only to colistin and, more variably, fosfomycin and tigecycline, are encountered with increasing frequency, including in Korea. Some ESBLs and carbapenemases have become associated with strains that have great epidemic potential, spreading across countries and continents; examples include Escherichia coli sequence type (ST)131 with CTX-M-15 ESBL and Klebsiella pneumoniae ST258 with KPC carbapenemases. Both of these high-risk lineages have reached Korea. In other cases, notably New Delhi Metallo carbapenemase, the relevant gene is carried by promiscuous plasmids that readily transfer among strains and species. Unless antibiotic stewardship is reinforced, microbiological diagnosis accelerated, and antibiotic development reinvigorated, there is a real prospect that the antibiotic revolution of the 20th century will crumble.

                Author and article information

                European Journal of Microbiology and Immunology
                Akadémiai Kiadó
                March 2018
                : 8
                : 1
                : 20-24
                [ 1 ]Department of Biomedical Sciences, Ladoke Akintola University of Technology , Ogbomoso, Osogbo Campus, Nigeria
                [ 2 ]Antimicrobials Research Group, Immunity and Infection, Institute of Microbiology and Infection, University of Birmingham , Birmingham, United Kingdom
                Author notes

                Corresponding author: David Olusoga Ogbolu; Department of Biomedical Science, College of Health Sciences, Ladoke Akintola University of Technology, Ogbomoso, PMB 4000, Nigeria; Phone: +2347055776547; E-mail: doogbolu@ or olusogadave@

                © 2018 The Author(s)

                This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium for non-commercial purposes, provided the original author and source are credited, a link to the CC License is provided, and changes - if any - are indicated.

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                Pages: 5
                Original Research Paper


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