Search

Background: Efflux of antibiotics is an effective resistance mechanism among antibiotic-resistant Staphylococcus aureus. This systematic review aims to evaluate the frequency and expression of efflux pump genes in S.aureus around the world., Method: A comprehensive literature search of several databases (Medline Pub Med, ISI, Scopus, Google Scholar, ISC, Science direct and Persian Journals Online, and citation lists) was performed. We considered published studies from 2001 to 2018. Articles reporting the prevalence and expression of efflux pump genes were selected., Result: Among 183 articles, 36 studies were selected. Of the 36, 23 articles were conducted in Asia.6 in Europe, 5 in America and 2 in African countries. In most of these studies norA, norB, qacA/B genes were commonly evaluated by molecular methods. The presence of efflux pump genes such as norA, norB, norC, mepA, mdeA, qacA/B was detected by PCR in 21 studies and over-expression of genes were reported in 13 studies. The most frequently reported genes in Asia were norA (75%), norB (60%), mepA (35%), mdeA (33%) and qacA/B (20.8%). In European studies, the prevalence of norB was mostly reported among S.aureus isolates and norA and qacA/B were commonly found in similar studies in America. The investigation of gene expression patterns showed that norA was most frequent single-pattern in Asia and America, norB or mdeA in Europe., Conclusion: According to this study MDR efflux pumps not only cause high-level resistance but also it considerably associated with over-expression of these genes. Due to the selective pressure on MRSA isolate, the enormous diversity of plasmid-encoded genes had been recorded in different regions, owing to the various numbers and types of isolates in each study or types of disinfectants for general use., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Enterobacteriaceae producing the Ambler class D OXA-48 carbapenemase, combined with additional resistance mechanisms, such as permeability defects or cocarriage of class A, B, or C β-lactamases, can become highly resistant to most β-lactams currently in use, including carbapenems. A total of 45,872 Enterobacteriaceae clinical isolates collected in 39 countries as part of the International Network for Optimal Resistance Monitoring (INFORM) global surveillance study in 2012 to 2015 were tested for susceptibility to β-lactams and comparator agents using the Clinical and Laboratory Standards Institute broth microdilution methodology and screened for the presence of β-lactamases. The bla OXA-48 and bla OXA-48-like genes were detected in 333 isolates across 14 species of Enterobacteriaceae collected in 20 countries across the globe. Few agents tested were effective in vitro against the overall collection of OXA-48-producers ( n = 265), with tigecycline (MIC 90 , 2 µg/ml; 92.5% susceptible), ceftazidime-avibactam (MIC 90 , 4 µg/ml; 92.5% susceptible), and aztreonam-avibactam (MIC 90 , 0.5 µg/ml; 99.6% of isolates with MIC ≤8 µg/ml) demonstrating the greatest activity. Similarly, colistin (MIC 90 , 1 µg/ml; 94.2% susceptible), tigecycline (MIC 90 , 2 µg/ml; 92.6% susceptible), ceftazidime-avibactam (MIC 90 , >128 µg/ml; 89.7% susceptible), and aztreonam-avibactam (MIC 90 , 4 µg/ml; 100% of isolates with MIC ≤8 µg/ml) were most active against OXA-48-like-positive isolates ( n = 68). The in vitro activity of ceftazidime-avibactam was improved against the subset of metallo-β-lactamase (MBL)-negative, OXA-48- and OXA-48-like-positive isolates (99.2% and 100% susceptible, respectively). The data reported here support the continued investigation of ceftazidime-avibactam and aztreonam-avibactam for the treatment of infections caused by carbapenem-resistant Enterobacteriaceae carrying OXA-48 and OXA-48-like β-lactamases in combination with serine- or metallo-β-lactamases., (Copyright © 2018 American Society for Microbiology.)

The extended-spectrum β-lactamase gene bla CTX-M-2 is mainly associated with ISCR1 embedded in complex sul1-type integrons, but information on the genetic context of plasmids harboring the ISCR1-bla CTX-M-2 module remains limited. In this study, a bla CTX-M-2 -harboring plasmid (pYD786-1) belonging to the sequence type 2 (ST2)-IncHI2 plasmid type and isolated from an Escherichia coli ST410 clinical strain was sequenced and analyzed. pYD786-1 belongs to the APEC-O1-R-type IncHI2 plasmids, which are widely distributed in human, poultry, and livestock strains. It contains a multidrug resistance mosaic region (MRR) consisting of a Tn21::In2 transposon backbone augmented by acquisition of duplicate ISCR1-bla CTX-M-2 modules. Tn2411, a Tn21::In2 precursor, likely played a role in the generation of the MRR in pN13-01290_23, the putative progenitor plasmid of pYD786-1, found in a foodborne Salmonella strain. Tn21/Tn2411::In::ISCR1-bla CTX-M-2 derivatives, including pYD786-1, have been identified in strains from Europe, South America, and the United States, suggesting potential global dissemination of the bla CTX-M-2 modules mediated by this vehicle., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

In view of continued high clinical prevalence of infections involving extended-spectrum β-lactamase (ESBL)-producing Escherichia coli, this study sought to characterise the blaCTX-M genes, their associated mobile genetic elements and the integrons present in 100 ESBL-producing E. coli isolates collected in a Dublin hospital and associated community healthcare facilities. Polymerase chain reaction (PCR) mapping and sequencing was used to detect blaCTX-M alleles, their associated insertion sequences (ISs) and class 1 and 2 integrons in the collection. ESBL plasmids were characterised by PCR-based replicon typing and replicon sequence typing (RST). Cefotaximases were harboured by 94% of isolates (66 blaCTX-M-15, 8 blaCTX-M-14, 7 blaCTX-M-1, 4 blaCTX-M-3, 3 blaCTX-M-9, 2 blaCTX-M-27, 2 blaCTX-M-55, 1 blaCTX-M-32 and 1 blaCTX-M-2). An ISEcp1 promoter was linked to a group 1 blaCTX-M gene in 45% of isolates. A further 34% of isolates contained blaCTX-M-15 downstream of IS26, an arrangement typical of epidemic UK strain A. Class 1 integrons were found in 66% of isolates, most carrying trimethoprim/aminoglycoside resistance genes. CTX-M plasmids were primarily of multireplicon IncF or IncI1 type, but IncN and unidentified types were also found. Novel IncF RSTs F1:A-:B-, F45:A1:B-, F45:A4:B- and a novel IncI1 sequence type, ST159, were identified. CTX-M plasmids and integrons resembled those identified recently in animal isolates from Ireland and Western Europe. The molecular epidemiology of CTX-M-producing E. coli in Dublin suggests that horizontal spread of mobile genetic elements contributes to antimicrobial resistant human infections. Further investigations into whether animals or animal products represent an important local reservoir for these elements are warranted.

The study aimed to characterize beta-lactam resistance mechanisms of Enterobacteriaceae isolates recovered from diseased dogs and cats between 2008 and 2010 in a European surveillance program (ComPath I) for the antibiotic susceptibility of bacterial pathogens. A total of 608 non-duplicated Enterobacteriaceae isolates were obtained prior antibiotic treatment from diseased dogs (n=464) and cats (n=144). Among the 608 Enterobacteriaceae isolates, 22 presented a minimal inhibitory concentration against cefotaxime above EUCAST breakpoints of susceptibility. All the 22 isolates remained susceptible to carbapenems. Ten isolates were confirmed as extended-spectrum-beta-lactamase (ESBL) producers by PCR-sequencing of bla coding genes including 9 blaCTX-M (CTX-M-1, 14, 15, 32,…) and 1 blaTEM-52 and 12 were AmpC-producing isolates (10 plasmidic CMY-2 group and 2 isolates overexpressing their chromosomal AmpC). ESBLs and plasmid-mediated AmpC (pAmpC)-producing isolates were mainly recovered from dogs (n=17) suffering from urinary tract infections (n=13) and originated from eight different countries. ESBL-bearing plasmids were mostly associated with IncFII incompatibility groups while CMY-2 was predominantly associated with plasmid of the IncI1 group. ESBL/pAmpC-producing Escherichia coli belonged to phylogroup A (n=5), B2 (n=4), and D (n=5). Multilocus sequence typing analysis revealed that among three CTX-M-15-producing E. coli, two belong to sequence type (ST) 131 and one to ST405. The presence of CTX-M-15 including on IncFII plasmids in E. coli ST131-B2 has also been described in isolates of human origin. This suggests the possibility of exchanges of these isolates from humans to companion animals or vice-versa.

We evaluated doripenem-resistant Acinetobacter baumannii-Acinetobacter calcoaceticus complex (ACB; n = 411) and Enterobacteriaceae (n = 92) isolates collected from patients from 14 European and Mediterranean countries during 2009 to 2011 for the presence of carbapenemase-encoding genes and clonality. Following susceptibility testing, carbapenem-resistant (doripenem MIC, >2 μg/ml) isolates were screened for carbapenemases. New β-lactamase genes were expressed in a common background and susceptibility was tested. Class 1 integrons were sequenced. Clonality was evaluated by pulsed-field gel electrophoresis and multilocus sequence typing (Pasteur scheme). Relative expression of β-lactam intrinsic resistance mechanisms was determined for carbapenemase-negative Enterobacteriaceae. ACB and Enterobacteriaceae displayed 58.9 and 0.9% doripenem resistance, respectively. bla(OXA-23), bla(OXA-58), and bla(OXA-24/OXA-40) were detected among 277, 77, and 29 ACB, respectively (in 8, 6, and 5 countries). Ten Turkish isolates carried bla(GES-11) or bla(GES-22). GES-22 (G243A and M169L mutations in GES-1) had an extended-spectrum β-lactamase profile. A total of 33 clusters of ≥ 2 ACB isolates were observed, and 227 isolates belonged to sequence type 2/international clone II. Other international clones were limited to Turkey and Israel. Doripenem-resistant Enterobacteriaceae increased significantly (0.7 to 1.6%), and 15 blaKPC-2- and 22 blaKPC-3-carrying isolates, mostly belonging to clonal complexes 11 and 258, were observed. Enterobacteriaceae isolates producing OXA-48 (n = 16; in Turkey and Italy), VIM-1 (n = 10; in Greece, Poland, and Spain), VIM-26 (n = 1; in Greece), and IMP-19, VIM-4, and the novel VIM-35 (n = 1 each from Poland) were detected. VIM-35 had one substitution compared to VIM-1 (A235T) and a similar susceptibility profile. One or more resistance mechanisms were identified in 4/6 carbapenemase-negative Enterobacteriaceae. This broad evaluation confirms results from country-specific surveys and shows a highly diverse population of carbapenemase-producing ACB and Enterobacteriaceae in Europe and Mediterranean countries., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

The Standard European Vector Architecture (SEVA) toolkit is a simple and powerful resource for constructing optimal plasmid vectors based on a backbone and three interchangeable modules flanked by uncommon restriction sites. Functional modules encode several origins of replication, diverse antibiotic selection markers, and a variety of cargoes with different applications. The backbone and DNA modules have been minimized and edited for flaws in their sequence and/or functionality. A protocol for the utilization of the SEVA platform to construct transcriptional and translational fusions between a promoter under study (the arsenic-responsive Pars of Pseudomonas putida KT2440) and the reporter lacZ gene is described. The resulting plasmid collection was instrumental to measure and compare the β-galactosidase activity that report gene expression (i.e., transcription and translation) in different genetic backgrounds.

Antimicrobial resistance in hospital and community-onset bacterial infections is a significant source of patient morbidity and mortality. In the past decade, we have witnessed the increasing recovery of carbapenem-resistant Gram-negative bacteria. For many isolates, carbapenem resistance is due to the production of carbapenemases, β-lactamases that can inactivate carbapenems and frequently other β-lactam antibiotics. Currently, these enzymes are mainly found in three different β-lactamase classes (class A, B and D). Regardless of the molecular classification, there are few antimicrobials available to treat infections with these organisms and data regarding agents in development are limited to in vitro studies. This article focuses on the epidemiology of carbapenemase-producing Gram-negative bacteria. We also review available agents and those in development with potential activity against this evolving threat.

Diaporthe helianthi is the causal agent of sunflower stem canker, a serious pathogen of sunflower in Europe, which has been sporadically recorded in Italy. A collection of 26 Diaporthe helianthi isolates deriving from different geographic origins was analysed in order to determine the presence of extra-chromosomal genetic determinants and their molecular diversity. Extra-chromosomal bands in total genomic DNAs were identified in every French and the Yugoslavian isolate and in only one Italian isolate, while no Romanian and Argentinean isolates resulted to host any plasmids. When tested for their chemicophysical nature, they were recognised as linear plasmids sized about 2.3 Kb. A more detailed analysis was performed on a plasmid purified from a French isolate (plasmid F). Its intracellular localisation resulted as mitochondrial. Plasmid F was also exploited as a probe in Southern hybridisation experiments, in which it recognised only plasmids present in the genomes of French and Yugoslavian isolates (countries were the disease has a heavy incidence) indicating a strong correlation to geographic origin. An RFLP hybridisation analysis performed on genomic DNAs revealed a homogeneous restriction pattern in all French and Yugoslavian isolates, suggesting molecular homology among plasmids present in those isolates.