Genetic relatedness among isolates of Shigella sonnei carrying class 2 integrons in Tehran, Iran, 2002–2003

<p>Abstract</p> <p>Background</p> <p><it>Shigella </it>spp. are major cause of diarrhoeal disease in both developing and developed countries. <it>Shigella sonnei </it>is the serogroup of <it>Shigella </it>most frequently responsible for sporadic and epidemic enteritis in developed countries. In recent years the emergence and spread of <it>S. sonnei </it>biotype g carrying class 2 integron have been frequently reported in many countries. Recently, <it>S. sonnei </it>has been reported as the prevalent serogroup of <it>Shigella </it>in Iran.</p> <p>The present study was carried out to investigate phenotypic and genetic characteristics of <it>Shigella sonnei </it>isolates identified in the years 2002 and 2003 in Tehran, Iran.</p> <p>Methods</p> <p>Biotyping, drug susceptibility testing, pulsed field gel electrophoresis (PFGE) and analysis of class 2 integrons have been carried out on 60 <it>S. sonnei </it>isolates, including 57 sporadic isolates from paediatric cases of shigellosis occurring in 2002 and 2003, two sporadic isolates recovered in 1984 and the ATCC 9290 strain.</p> <p>Results</p> <p>Biotype g and resistance to streptomycin, sulfamethoxazole-trimethoprim and tetracycline were exhibited by 54 of the 57 recent isolates. Of the 54 biotype g isolates, 28 exhibited a class 2 integron of 2161 bp, and 24 a class 2 integron of 1371 bp, respectively. Class 2 integrons were not detected in four isolates only, including the two endemic isolates recovered in 1984 and two strains from recent sporadic cases. PFGE divided the strains into eight pulsotypes labeled A to H, three major pulsotypes – A to C – including the large majority of the recent sporadic <it>S. sonnei </it>isolates. Pulsotypes A and C were the most prevalent groups, accounting for 41.6% and 35.0%, respectively, of the isolates under study.</p> <p>Conclusion</p> <p>The results suggest that biotype g, class 2 integron carrying <it>S. sonnei </it>are prevalent in our geographic area. <it>S. sonnei </it>isolated in the years 2002 and 2003 could be attributed to a few predominant clusters including, respectively, strains with pulsotypes B and C carrying a 2161 bp class 2 integron, and those having pulsotype A and a 1371 bp class 2 integron. A few epidemic clones are responsible for the apparently endemic occurrence of shigellosis in Tehran, Iran.</p

A unified approach to molecular epidemiology investigations: tools and patterns in California as a case study for endemic shigellosis

<p>Abstract</p> <p>Background</p> <p>Shigellosis causes diarrheal disease in humans from both developed and developing countries, and multi-drug resistance is an emerging problem. The objective of this study is to present a unified approach that can be used to characterize endemic and outbreak patterns of shigellosis using use a suite of epidemiologic and molecular techniques. The approach is applied to a California case study example of endemic shigellosis at the population level.</p> <p>Methods</p> <p>Epidemiologic patterns were evaluated with respect to demographics, multi-drug resistance, antimicrobial resistance genes, plasmid profiles, and pulsed-field gel electrophoresis (PFGE) fingerprints for the 43 <it>Shigella </it>isolates obtained by the Monterey region health departments over the two year period from 2004-2005.</p> <p>Results</p> <p>The traditional epidemiologic as well as molecular epidemiologic findings were consistent with endemic as compared to outbreak shigellosis in this population. A steady low level of cases was observed throughout the study period and high diversity was observed among strains. In contrast to most studies in developed countries, the predominant species was <it>Shigella flexneri </it>(51%) followed closely by <it>S. sonnei </it>(49%). Over 95% of <it>Shigella </it>isolates were fully resistant to three or more antimicrobial drug subclasses, and 38% of isolates were resistant to five or more subclasses. More than half of <it>Shigella </it>strains tested carried the <it>tetB</it>, <it>catA</it>, or <it>bla</it>_TEMgenes for antimicrobial resistance to tetracycline, chloramphenicol, and ampicillin, respectively.</p> <p>Conclusion</p> <p>This study shows how epidemiologic patterns at the host and bacterial population levels can be used to investigate endemic as compared to outbreak patterns of shigellosis in a community. Information gathered as part of such investigations will be instrumental in identifying emerging antimicrobial resistance, for developing treatment guidelines appropriate for that community, and to provide baseline data with which to compare outbreak strains in the future.</p

Radical Immersions: Navigating between virtual/physical environments and information bubbles - DRHA 2019 Conference Proceedings

This publication consists of the peer-reviewed papers and posters presented at the DRHA 2019 Conference "Radical Immersions: navigating between virtual / physical environments and information bubbles". The conference was held at Watermans Arts Centre, London (8-10 September 2019). For further information: http://www.2019.drha.uk

Whole genome sequencing provides an unambiguous link between Salmonella Dublin outbreak strain and a historical isolate

Salmonella enterica subsp. enterica serovar Dublin is an uncommon cause of human salmonellosis; however, a relatively high proportion of cases are associated with invasive disease. The serotype is associated with cattle. A geographically diffuse outbreak of S. Dublin involving nine patients occurred in Ireland in 2013. The source of infection was not identified. Typing of outbreak associated isolates by pulsed-field gel electrophoresis (PFGE) was of limited value because PFGE has limited discriminatory power for S. Dublin. Whole genome sequencing (WGS) showed conclusively that the isolates were closely related to each other, to an apparently unrelated isolate from 2011 and distinct from other isolates that were not readily distinguishable by PFGE

First Report of Extended-Spectrum-β-Lactamase-Producing Salmonella enterica Serovar Kentucky Isolated from Poultry in Ireland▿

Therapy of invasive human salmonellosis is complicated by increasing antimicrobial resistance. Food animals are the principal source of infection with nontyphoid Salmonella. We report the emergence of broad-spectrum-cephalosporin resistance in Salmonella enterica serovar Kentucky in poultry in Ireland

First report of extended-spectrum- -lactamase-producing salmonella enterica serovar kentucky isolated from poultry in ireland

Therapy of invasive human salmonellosis is complicated by increasing antimicrobial resistance. Food animals are the principal source of infection with nontyphoid Salmonella. We report the emergence of broadspectrum-cephalosporin resistance in Salmonella enterica serovar Kentucky in poultry in Ireland

Antimicrobial resistance and genetic diversity of shigella sonnei isolates from western ireland, an area of low incidence of infection

Shigella sonnei is a significant cause of gastroenteritis in both developing and industrialized countries. Definition of the diversity and antimicrobial susceptibility of S. sonnei isolates may be helpful in the management of individual cases and outbreaks. Antimicrobial susceptibility testing and pulsed-field gel electrophoresis (PFGE) were performed with 67 isolates of S. sonnei predominantly (n = 59) from three counties in the west of Ireland. Phage typing (n = 17), plasmid profiling (n = 28), and integron analysis (n = 24) were performed with subsets of strains. PFGE typing permitted recognition of two major clusters: PFGE type A (n = 53) and PFGE type B (n = 14). PFGE type A was associated with resistance to ampicillin, streptomycin, and sulfonamides (51 of 53 isolates), and those that were phage typed (n = 6) were phage type 3. PFGE type B was associated with resistance to streptomycin, sulfonamides, tetracycline, and trimethoprim (11 of 14 isolates) and phage type 6 (9 of 11 isolates). Fifteen different plasmid profiles were identified among the 28 isolates analyzed. A class 2 integron was present in all 14 PFGE type B isolates. One of these isolates also contained a class 1 integron and showed a unique variant of the PFGE type B pattern. Sequence analysis of the gene cassette structures contained within these integrons identified distinct open reading frames that encoded determinants of resistance to trimethoprim, streptomycin, and streptothricin. Our data demonstrate two predominant PFGE types among S. sonnei isolates circulating in this region. The limited diversity of the S. sonnei isolates in this region means that detection of isolates indistinguishable by PFGE and according to their antibiograms in two or more patients is not persuasive evidence of a common-source food- or waterborne outbreak. Indistinguishable plasmid profiles in addition to indistinguishable PFGE and antibiogram types may be more suggestive of an epidemiologically relevant link between cases

Antimicrobial resistance and genetic diversity of shigella sonnei isolates from western ireland, an area of low incidence of infection

Shigella sonnei is a significant cause of gastroenteritis in both developing and industrialized countries. Definition of the diversity and antimicrobial susceptibility of S. sonnei isolates may be helpful in the management of individual cases and outbreaks. Antimicrobial susceptibility testing and pulsed-field gel electrophoresis (PFGE) were performed with 67 isolates of S. sonnei predominantly (n = 59) from three counties in the west of Ireland. Phage typing (n = 17), plasmid profiling (n = 28), and integron analysis (n = 24) were performed with subsets of strains. PFGE typing permitted recognition of two major clusters: PFGE type A (n = 53) and PFGE type B (n = 14). PFGE type A was associated with resistance to ampicillin, streptomycin, and sulfonamides (51 of 53 isolates), and those that were phage typed (n = 6) were phage type 3. PFGE type B was associated with resistance to streptomycin, sulfonamides, tetracycline, and trimethoprim (11 of 14 isolates) and phage type 6 (9 of 11 isolates). Fifteen different plasmid profiles were identified among the 28 isolates analyzed. A class 2 integron was present in all 14 PFGE type B isolates. One of these isolates also contained a class 1 integron and showed a unique variant of the PFGE type B pattern. Sequence analysis of the gene cassette structures contained within these integrons identified distinct open reading frames that encoded determinants of resistance to trimethoprim, streptomycin, and streptothricin. Our data demonstrate two predominant PFGE types among S. sonnei isolates circulating in this region. The limited diversity of the S. sonnei isolates in this region means that detection of isolates indistinguishable by PFGE and according to their antibiograms in two or more patients is not persuasive evidence of a common-source food- or waterborne outbreak. Indistinguishable plasmid profiles in addition to indistinguishable PFGE and antibiogram types may be more suggestive of an epidemiologically relevant link between cases