Mechanisms of resistance to expanded-spectrum cephalosporins in Escherichia coli isolates recovered in a Spanish hospital

Briñas, Laura; Lantero, M; Diego, Isabel de; Alvarez, M.; Zarazaga, Myriam; Torres, Carmén

doi:10.1093/jac/dki370

Cited by 44 publications

(30 citation statements)

References 10 publications

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“…One strain had a 2-bp insertion in the ampC promoter spacer region (variant 5) and a plasmid-carried ampC gene; both mechanisms may have contributed to AmpC activity in this strain. The observed ratio of AmpC production due to chromosomal ampC upregulation versus plasmid-mediated AmpC is in accordance with the distribution observed in stud-ies conducted in France, Spain, and Norway (6,14,20). We did not detect any strain that was positive in the genetic analysis and negative in all three phenotypic confirmation tests.…”

Section: Discussionsupporting

confidence: 90%

Detection of AmpC Beta-Lactamase in Escherichia coli: Comparison of Three Phenotypic Confirmation Assays and Genetic Analysis

et al. 2011

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Two mechanisms account for AmpC activity in Escherichia coli, namely, mutations in the ampC promoter and attenuator regions resulting in ampC overexpression and acquisition of plasmid-carried ampC genes. In this study, we analyzed 51 clinical E. coli isolates with reduced susceptibility to amoxicillin-clavulanic acid, piperacillin-tazobactam, or extended-spectrum cephalosporins for the presence of AmpC production. Three phenotypic AmpC confirmation assays (cefoxitin-cloxacillin disk diffusion test, cefoxitin-EDTA disk diffusion test, and AmpC Etest) were compared for the detection of AmpC activity. All 51 isolates were characterized genetically by mutational analysis of the chromosomal ampC promoter/attenuator region and by PCR detection of plasmid-carried ampC genes. Altogether, 21/51 (41%) E. coli isolates were considered true AmpC producers. AmpC activity due to chromosomal ampC promoter/attenuator mutations was found in 12/21 strains, and plasmid-carried ampC genes were detected in 8/21 isolates. One strain contained both ampC promoter mutations and a plasmid-carried ampC gene. All three phenotypic tests were able to detect the majority (>90%) of AmpC-positive strains correctly. Cefoxitin resistance was found to be a discriminative parameter, detecting 20/21 AmpC-producing strains. Susceptibility to extended-spectrum cephalosporins, e.g., ceftriaxone, ceftazidime, and cefotaxime, was found in 9 of the 21 AmpC-positive strains. Considering the elevated zone diameter breakpoints of the 2010 CLSI guidelines, 2/21 AmpC-positive strains were categorized as susceptible to extended-spectrum cephalosporins.

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Section: Discussionsupporting

confidence: 90%

Detection of AmpC Beta-Lactamase in Escherichia coli: Comparison of Three Phenotypic Confirmation Assays and Genetic Analysis

et al. 2011

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“…Many of the P ϩ G Ϫ isolates had ␤-lactam resistance and lacked a bla-CMY-2 gene, which is the most common genetic determinant of expanded-spectrum cephalosporin resistance in Enterobacteriaceae in the United States (15). We found that these isolates had mutations in the promoter and attenuator sequences of the E. coli chromosomal ampC gene that have also been reported from human clinical E. coli isolates in South Africa (39), Spain (7,40), France (12,13,35), Belgium (6), Norway (22), and Denmark (26). They have also been described in animal source E. coli isolates, including those from cattle in Canada (38) and the United Kingdom (34) and pigs in Spain (19) and in E. coli collected from recreational water samples in T A T G T E160 SSuT C A T G T E1026 ASSuTGK T A T G T E1030 ACSSuTKSxtNalRcazAmc T A T G T E1039 ASSuTGKNalRcazAmc T A T G T E1067 ASSuTKCazAmc T A T G T E2534 SSuTGKSxtAmik Canada (37).…”

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confidence: 54%

Genotypic-Phenotypic Discrepancies between Antibiotic Resistance Characteristics of Escherichia coli Isolates from Calves in Management Settings with High and Low Antibiotic Use

Davis

Besser

Orfe

et al. 2011

Appl Environ Microbiol

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We hypothesized that bacterial populations growing in the absence of antibiotics will accumulate more resistance gene mutations than bacterial populations growing in the presence of antibiotics. If this is so, the prevalence of dysfunctional resistance genes (resistance pseudogenes) could provide a measure of the level of antibiotic exposure present in a given environment. As a proof-of-concept test, we assayed field strains of Escherichia coli for their resistance genotypes using a resistance gene microarray and further characterized isolates that had resistance phenotype-genotype discrepancies. We found a small but significant association between the prevalence of isolates with resistance pseudogenes and the lower antibiotic use environment of a beef cow-calf operation versus a higher antibiotic use dairy calf ranch (Fisher's exact test, P ‫؍‬ 0.044). Other significant findings include a very strong association between the dairy calf ranch isolates and phenotypes unexplained by well-known resistance genes (Fisher's exact test, P < 0.0001). Two novel resistance genes were discovered in E. coli isolates from the dairy calf ranch, one associated with resistance to aminoglycosides and one associated with resistance to trimethoprim. In addition, isolates resistant to expanded-spectrum cephalosporins but negative for bla CMY-2 had mutations in the promoter regions of the chromosomal E. coli ampC gene consistent with reported overexpression of native AmpC beta-lactamase. Similar mutations in hospital E. coli isolates have been reported worldwide. Prevalence or rates of E. coli ampC promoter mutations may be used as a marker for high expanded-spectrum cephalosporin use environments.

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“…Such resistance mechanisms are prevalent in developing countries, particularly among different Gram-negative and Gram-positive bacteria, due to the availability and affordability of antibiotics like ampicillin, streptomycin, choloramphenicol, tetracycline and trimethoprim/sulphamethoxazole [22]. In addition, resistance to other antibiotics -particularly the new generations of cephalosporins, aminoglycosides and quinolones -has been reported [23][24][25][26][27], along with high rates of extended spectrum β-lactamase and /or Amp-C enzyme production [28]. One explanation for these high resistance rates could be antibiotic usage in the respective institutions.…”

Section: Discussionmentioning

confidence: 99%

Fluoroquinolone resistant mechanisms in methicillin-resistant Staphylococcus aureus clinical isolates in Cairo, Egypt

Hashem

Yassin

Zedan

et al. 2013

J Infect Dev Ctries

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Introduction: Methicillin-resistant Staphylococcus aureus (MRSA) is a persistent problem in community and health care settings. Fluoroquinolones are among the drugs of choice used to treat MRSA infections. This study aims to identify different mechanisms of fluoroquinolne resistance in local MRSA random sampling isolates in Cairo, Egypt. Methodology: A total of 94 clinical isolates of S. aureus were collected from two major University hospitals in Cairo. Identification was confirmed by appropriate morphological, cultural, and biochemical tests. The antibiotic susceptibility pattern was determined for all isolates. The possible involvement of efflux pumps in mediating fluoroquinolone resistance as well as changes in the quinolone resistance determining region (QRDR) of gyrA and gyrB genes were investigated Results: A total of 45 isolates were found to be MRSA, among which 26 isolates were found to be fluoroquinolone-resistant. The MIC values of the tested fluoroquinolones in the presence of the efflux pump inhibitors omeprazole and piperine were reduced. Measuring the uptake of ciprofloxacin upon the addition of the efflux pump inhibitor omeprazole, an increased level of accumulation was observed. Non-synonymous and silent mutations were detected in the QRDR of gyrA and gyrB genes. Conclusions: These results shed light on some of the resistance patterns of MRSA strains isolated from local health care settings in Cairo, Egypt. The resistance of these MRSA towards fluoroquinolones does not depend only on mutation in target genes; other mechanisms of resistance such as the permeability effect, efflux pumps and decreased availability of quinolones at the target site can also be involved.

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Mechanisms of resistance to expanded-spectrum cephalosporins in Escherichia coli isolates recovered in a Spanish hospital

Abstract: Approximately 1.5% of the E. coli isolates of our hospital harboured ESBL genes, those of the CTX-M-9 group being the most common ones.

Cited by 44 publications

References 10 publications

Detection of AmpC Beta-Lactamase in Escherichia coli: Comparison of Three Phenotypic Confirmation Assays and Genetic Analysis

Detection of AmpC Beta-Lactamase in Escherichia coli: Comparison of Three Phenotypic Confirmation Assays and Genetic Analysis

Genotypic-Phenotypic Discrepancies between Antibiotic Resistance Characteristics of Escherichia coli Isolates from Calves in Management Settings with High and Low Antibiotic Use

Fluoroquinolone resistant mechanisms in methicillin-resistant Staphylococcus aureus clinical isolates in Cairo, Egypt

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