Diversity of genetic lineages among CTX-M-15 and CTX-M-14 producing Escherichia coli strains in a Tunisian hospital.
ABSTRACT Fourteen broad-spectrum-cephalosporin-resistant Escherichia coli isolates were recovered between June and December 2007 in a Tunisian hospital. Genes encoding extended-spectrum-beta-lactamases (ESBL) and other resistance genes were characterized by PCR and sequencing. The following ESBL genes were identified: bla (CTX-M-15) (12 isolates), bla (CTX-M-14a) (one isolate), and bla (CTX-M-14b) (one isolate). The bla (OXA-1) gene was detected in 13 bla (CTX-M)-producing strains and a bla (TEM-1) gene in 6 of them. The ISEcp1 sequence was found upstream of bla (CTX-M) genes in 8 of 14 strains, and orf477 or IS903 downstream of this gene in 13 strains. Nine of the strains carried class 1 integrons and five different gene cassette arrangements were detected, dfrA17-aadA5 being the most common. One of the strains (bla (CTX-M-14a)-positive) harbored three class 1 integrons, and one of them was non-previously described containing as gene cassettes new variants of aac(6')-Ib and cmlA1 genes and it was linked to the bla (CTX-M-14a) gene flanked by a truncated ISEcp1 sequence (included in GenBank with accession number JF701188). CTX-M-15-producing strains were ascribed to phylogroup B2 (six isolates) and D (six isolates). Multilocus-sequence-typing revealed ten different sequence-types (STs) among ESBL-positive E. coli strains with prevalence of ST405 (four strains of phylogroup D) and ST131 types (two strains of phylogroup B2 and serogroup O25b). A high clonal diversity was also observed among studied strains by pulsed-field-gel-electrophoresis (11 unrelated profiles). CTX-M-15 is an emergent mechanism of resistance in the studied hospital and the world-disseminated 0:25b-ST131-B2 and ST405-D clones have been identified among CTX-M-15-producing isolates.
SourceAvailable from: Ben Slama KarimJournal of chemotherapy (Florence, Italy) 02/2014; DOI:10.1179/1973947814Y.0000000172 · 1.07 Impact Factor
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ABSTRACT: Eighty-four multidrug-resistant Klebsiella pneumoniae (MDR-KP) isolates from a Chinese hospital from January to October 2012 were evaluated to characterize the coexistence of 16S rRNA methylase, extended-spectrum β-lactamase, carbapenemase, and plasmid-mediated quinolone resistance determinants and their association with mobile genetic elements. Among the 84 MDR-KP isolates studied, 19 isolates exhibited high-level resistance to amikacin mediated by the production of the 16S rRNA methylase. They carried 19 armA genes (22.9%) and three rmtB genes (3.6%). CTX-M genes were found in all of the isolates. Among these amrA- or rmtB/CTX-M-producing K. pneumoniae isolates, 31.6% carried the carbapenemase genes (blaKPC-2 [26.3%], blaIMP-4 [10.5%], and blaNDM-1 [5.3%]), which made them resistant to imipenem (minimum inhibitory concentration [MIC] ≥16 mg/L). All positive strains possessed qnr-like genes (16 qnrA1, 10 qnrS1, and 7 qnrB4 genes) and 18 harbored an aac(6')-Ib-cr gene. Mobile elements ISEcp1, IS26, ISCR1, ISAba125, and sul-1 integrons were detected in 19/19 (100%), 16/19 (84.2%), 18/19 (94.7%), 9/19 (47.4%), and 18/19 (94.7%) isolates, respectively. The mobilizing elements occurred in different combinations in the study isolates. Majority of armA and qnr genes were in MDR-KP strains carrying integrons containing the ISCR1. Close to 80% of blaTEM-1 and blaSHV-12 were linked to IS26 while ≥90% of blaCTX-Ms and blaCMYs were linked to ISEcp1. ISAba125 was located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants were available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 were cotransferred. This study points to the dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of resistance determinants in collection of clinical K. pneumoniae in China.Microbial drug resistance (Larchmont, N.Y.) 12/2014; 21(2). DOI:10.1089/mdr.2014.0073 · 2.52 Impact Factor
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ABSTRACT: Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBL) has been found all over the world, and risk factors for acquiring these bacteria involve hospital care and antibiotic treatment. Surveillance studies are present in Europe, North America, and Asia, but there is no summarizing research published on the situation in Africa. This review aims to describe the prevalence of ESBL-producing Enterobacteriaceae in hospital and community settings in Africa and the ESBL genes involved. A non-systematic literature search was performed in PubMed. All articles published between 2008 and 2012 were screened and read in full text. Relevant articles were assessed for quality of evidence and included in the review. Articles were divided into regional areas in Africa and tabulated. ESBL-producing Enterobacteriaceae in hospitalized patients and in communities varies largely between countries and specimens but is common in Africa. ESBLs (class A and D) and plasmid-encoded AmpC (pAmpC) were regularly found, but carbapenemases were also present. ESBL-producing Enterobacteriaceae in hospital and community settings in Africa is common. Surveillance of antimicrobial resistance needs to be implemented in Africa to tailor interventions targeted at stopping the dissemination of ESBL-producing Enterobacteriaceae.03/2014; 4. DOI:10.3402/iee.v4.20342