170,057 research outputs found
The global crisis of multidrug resistance: how to face healthcare associated infections without effective antibiotics?
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Antimicrobial resistance of Shigella sonnei isolates carrying class 2 integron in Northern Italy
No full textBackground: In the last decades, several reports on Shigella sonnei epidemiology from different countries have associated the epidemic circulation of this organism to a well defined strain, characterized by some proprierties, like a resistant phenotype streptomycin, sulfonamide, trimethoprim and tetracycline, a distinct XBaI pulsotype and the presence of class 2 integron. The objective of this study was to evaluate the genetic heterogeneity of molecular profiles, drug susceptibility pattern, and carriage of class 2 integron of S. sonnei collected in northern Italy. Materials: A total of twenty-five clinical isolates of S. sonnei identified in Lombardy region during the years 2009-2012 were studied. All isolates were subtyped by Pulsed-Field Gel Electropheresis (PFGE) according to the PulseNet protocol with XBaI enzyme to detect clusters and support epidemiological investigations. Furthermore, antimicrobial susceptibility testing was performed by the disk diffusion method as recommended by the National Committee of Clinical Laboratory Standards. Finally, polymerase chain reaction (PCR) was performed with the specific primer pair -hep74 and hep51- to detect the class 2 integron. Results: Eight XbaI pulsotypes with homology over 80% were recognized among the 25 clinical isolates. Twenty-three isolates were grouped in six clusters, while the remaining two isolates showed unique pulsotypes, one of which was reported in 2001 (Mammina et al., J. Clin. Microbiol., 2005). Two different class 2 integron structures were identified. Nine (36%) isolates contained a 2.22-kbp gene cassette (dhfr1, sat, and aad) were phenotypically resistant to trimethoprim and streptomycin, also ten (40%) isolate produced a smaller cassette structure of 1.37-kbp encoding only two genes within the cassette (dhfr1 and sat) were resistant to streptomycin. Finally, no class 2 integrons were detected in the remaining six (24%) isolates. Conclusion: The finding of our studies revealed the persistence of a pulsotype isolated in Lombardy in 2001. Moreover, ten S. sonnei isolates containing defective class 2 integron (1.37-kbp) were resistant to streptomycin. It is possible that in this case the streptomycin resistance may be due to aad gene present on a plasmid
Reinterpreting a community outbreak of <it>Salmonella enterica </it>serotype Enteritidis in the light of molecular typing
No full textAbstract Background In November 2005, a large outbreak due to Salmonella enterica serotype Enteritidis (S. Enteritidis) was observed within children who had eaten their meals at 53 school cafeterias in Florence and the surrounding area. A total of 154 isolates of S. Enteritidis were recovered from human cases between November 2005 and January 2006. All strains were assigned phage type 8 (PT8) and a common XbaI pulsotype. This paper reports the findings of a molecular epidemiological investigation performed on 124 strains of S. Enteritidis isolated in the years 2005 and 2006 in Florence and the surrounding area, including the epidemic isolates. Methods One hundred twenty-four human isolates of S. Enteritidis identified in the period January 2005 – December 2006 were submitted to molecular typing by single enzyme – amplified fragment length polymorphism (SE-AFLP). Results Molecular subtyping by SE-AFLP yielded five different profiles. In the pre-epidemic phase, type A included 78.4% of isolates, whereas only three (8.1%) belonged to type C. All isolates, but one, of the epidemic phase were indistinguishable and attributed to type C. In the post-epidemic period, a polymorphic pattern of SE-AFLP types was again recognized but type C accounted for 73.3% of the isolates during the first six months of 2006, whereas during the remaining six months type A regained the first place, including 52.0% of the isolates. Conclusion The epidemic event was attributed to the emergence and clonal expansion of a strain of S. Enteritidis PT8-SE-AFLP type C. Circulation of the epidemic clone was much more extensive than the surveillance and traditional laboratory data demonstrated.</p
<it>Shigella sonnei </it>biotype g carrying class 2 integrons in southern Italy: a retrospective typing study by pulsed field gel electrophoresis
No full textAbstract Background Emergence and global dissemination of multiresistant strains of enteric pathogens is a very concerning problem from both epidemiological and Public Health points of view. Shigella sonnei is the serogroup of Shigella most frequently responsible for sporadic and epidemic enteritis in developed countries. The dissemination is associated most often to human to human transmission, but foodborne episodes have also been described. In recent years the circulation of multiresistant strains of S. sonnei biotype g carrying a class 2 integron has been reported in many countries worldwide. In southern Italy a strain with similar properties has been responsible for a large community outbreak occurred in 2003 in Palermo, Sicily. The objective of this study was to date the emergence of the biotype g strain carrying the class 2 integron in southern Italy and to evaluate the genetic heterogeneity of biotype g S. sonnei isolated throughout an extended interval of time. Methods A total of 31 clinical isolates of S. sonnei biotype g identified in southern Italy during the years 1971–2000 were studied. The strains were identified at the serogroup level, characterized by biochemical tests and submitted to antimicrobial susceptibility testing. Molecular typing was performed by pulsed field gel electrophoresis (PFGE) after digestion of DNA by XbaI. Carriage of class 2 integrons was investigated by polymerase chain reaction (PCR) with specific primers and confirmed by restriction endonuclease analysis of amplicons. Results The 15 isolates of S. sonnei biotype g identified in the decade 1971–1980 showed highly heterogeneous drug resistance profiles and pulsotypes. None of the isolates was simultaneous resistant to streptomycin and trimethoprim and none was class 2 integron positive. On the contrary, this resistance phenotype and class 2 integron carriage were very common among the 16 strains of biotype g identified in the following two decades. Moreover, all the more recent isolates, but one, showed closely related pulsotypes. Conclusion Although our findings refer to a limited geographic area, they provide a snapshot of integron acquisition by an enteric pathogen responsible for several outbreaks in the years 2001–2003 in Italy. Molecular typing, indeed, suggests that the emergence of biotype g class 2 integron carrying S. sonnei in southern Italy should be backdated to at least the late 1980s. In the following decades, the circulation of biotype g appears to be sustained by multiresistant highly related strains. Similar trend are described in several countries, but the questions about mechanism of emergence and worldwide spread of this pathogen remain open.</p
Sorveglianza delle infezioni e delle colonizzazioni nosocomiali condotta presso la UTI dell'AOUP "P. Giaccone" di Palermo
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