Pulsed-field Electrophoresis Research Articles

Methicillin-resistant Staphylococcus aureus (MRSA) Isolated from Colombian Foods

Methicillin-resistant Staphylococcus aureus (MRSA) was identified as a nosocomial pathogen in the 1960s and it is associated with serious community-acquired and nosocomial diseases, particularly in immunocompromised patients. S. aureus also causes food poisoning and is the most important food-borne disease in Latin America. In Colombia, the Community acquired (CA-MRSA) increased by 4.4% between 2001 and 2006. However, the transmission of MRSA through food has not been well researched; its prevalence is unknown as is the risk of consumer exposure. It is important to determine the role of food in transmission of antibiotic-resistant bacteria, taking into account that the prevalence of MRSA varies according to geographical location. The aim of this study was to determine the prevalence of MRSA in Colombian foods and to typify isolated strains by detecting antimicrobial resistance, clonal groups and Toxin A gene. Resistance of 149 S. aureus strains isolated from food was determined by disk diffusion with oxacillin (1μg) and cefoxitin (30μg), Antimicrobial Susceptibility Test (AST) and mecA gene amplification. Positive strains were genotyped using pulsed field electrophoresis (PFGE). 5 (3.35%) of the 149 strains resistant to oxacillin and cefoxitin, were positive to mecA gene, indicating the presence of the SCC cassette. The electrophoretic pattern obtained by PFGE for these strains revealed that 4 (80%) of the 5 strains belong to the Chilean clone, with 100% genetic similarity; this clone has been associated with 65% of infections associated with health care. Furthermore, none of the 5 strains were positive to Toxin A gene. This is the first evidence of the presence of MRSA in food in Colombia. It is necessary to continue this research by extending the sampling and collecting enough information to carry out risk analysis of the danger.

Identification and Mechanism of Evolution of New Alleles Coding for the AIDA-I Autotransporter of Porcine Pathogenic Escherichia coli

Autotransporters are a large family of virulence factors of Gram-negative bacterial pathogens. The autotransporter adhesin involved in diffuse adherence (AIDA-I) is an outer membrane protein of Escherichia coli, which allows binding to epithelial cells as well as the autoaggregation of bacteria. AIDA-I is glycosylated by a specific heptosyltransferase encoded by the aah gene that forms an operon with the aidA gene. aidA is highly prevalent in strains that cause disease in pigs. Nevertheless, there are only two published whole-length sequences for this gene. In this study, we sequenced the aah and aidA genes of 24 aidA-positive porcine strains harboring distinct virulence factor profiles. We compared the obtained sequences and performed phylogenetic and pulsed-field electrophoresis analyses. Our results suggest that there are at least 3 different alleles for aidA, which are associated with distinct virulence factor profiles. The genes are found on high-molecular-weight plasmids and seem to evolve via shuffling mechanisms, with one of the sequences showing evidence of genetic recombination. Our work suggests that genetic plasticity allows the evolution of aah-aidA alleles that are selected during pathogenesis.

A Double Mutant between Fission Yeast Telomerase and RecQ Helicase Is Sensitive to Thiabendazole, an Anti-Microtubule Drug

In the fission yeast Schizosaccharomyces pombe, deletion of trt1(+) causes gradual telomere shortening, while deletion of pot1(+) causes rapid telomere loss. The double mutant between pot1 and RecQ helicase rqh1 is synthetically lethal. We found that the trt1 rqh1 double mutant was not synthetically lethal. The chromosome end fragments in both the trt1Δ rqh1Δ and the trt1Δ rqh1-hd (helicase dead) double mutants did not enter a pulsed-field electrophoresis gel. Both the trt1Δ rqh1Δ and the trt1Δ rqh1-hd double mutants were sensitive to the anti-microtubule drug thiabendazole. Moreover, the trt1Δ rqh1-hd double mutant displayed RPA foci on the chromosome bridge at high frequency in M phase cells. These phenotypes are very similar to that of the pot1Δ rqh1-hd double mutant, in which recombination intermediates accumulate at the chromosme ends in the M phase. These results suggest that the entangled chromosome ends, most likely recombination intermediates, are present in the M phase in the trt1Δ rqh1-hd double mutant.

Proteome-determined type-specific proteins of Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subspecies paratuberculosis (M. a. paratuberculosis) is a pathogen of ruminants, causing paratuberculosis (characterized by severe emaciation). The disease is endemic in many countries including the UK and places a severe economic burden on the global livestock industry.Two types of M. a. paratuberculosis can be classified by pulsed-field electrophoresis (I/III and II), which are phenotypically distinct and appear to have different host preferences. Proteomes of Type I and Type II M. a. paratuberculosis were analyzed by 2-D gel electrophoresis to determine if any significant differences existed between the subtypes. Seven different strains of Type I and 18 strains of Type II were analyzed and compared to detect type-specific differences. These ‘type-specific’ differences existed regardless of growth phase and were also exhibited in cells isolated directly from pathogenic lesions. Twenty-three spots predominated on the Type I profile, from which 17 proteins were identified. Twenty-one spots predominated on the Type II profile, from which 16 proteins were identified. None of the proteins identified as differentially represented on the profiles of Type I or Type II corresponded to open reading frames of the defining genomic regions as previously described for the Type I (sheep) and Type II (cattle).Sequence polymorphisms existing in Type I and II strains were identified in some open reading frames or regulatory regions of genes that correspond to proteins expressed in a type-specific fashion. The consequence of these is discussed in relation to protein expression and their impact on the type phenotype is discussed.

Suberoylanilide hydroxamic acid affects γH2AX expression in osteosarcoma, atypical teratoid rhabdoid tumor and normal tissue cell lines after irradiation

Osteosarcoma and atypical teratoid rhabdoid tumors are tumor entities with varying response to common standard therapy protocols. Histone acetylation affects chromatin structure and gene expression which are considered to influence radiation sensitivity. The aim of this study was to investigate the effect of the combination therapy with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) and irradiation on atypical teratoid rhabdoid tumors and osteosarcoma compared to normal tissue cell lines. Clonogenic assay was used to determine cell survival. DNA double-strand breaks (DSB) were examined by pulsed-field electrophoresis (PFGE) as well as by γH2AX immunostaining involving flow cytometry, fluorescence microscopy, and immunoblot analysis. SAHA lead to an increased radiosensitivity in tumor but not in normal tissue cell lines. γH2AX expression as an indicator for DSB was significantly increased when SAHA was applied 24h before irradiation to the sarcoma cell cultures. In contrast, γH2AX expression in the normal tissue cell lines was significantly reduced when irradiation was combined with SAHA. Analysis of initial DNA fragmentation and fragment rejoining by PFGE, however, did not reveal differences in response to the SAHA pretreatment for either cell type. SAHA increases radiosensitivity in tumor but not normal tissue cell lines. The increased H2AX phosphorylation status of the SAHA-treated tumor cells post irradiation likely reflects its delayed dephosphorylation within the DNA damage signal decay rather than chromatin acetylation-dependent differences in the overall efficacy of DSB induction and rejoining. The results support the hypothesis that combining SAHA with irradiation may provide a promising strategy in the treatment of solid tumors.

Clinical and molecular characterization of ESBL-producing enterobacteria isolated from bacteremia in a university hospital

Extended-spectrum-β-lactamases (ESBL) are plasmid-encoded enzymes that confer resistance to multiple antimicrobials. ESBL-producing enterobacteria that cause bacteremia limit therapeutic options and increase mortality. To perform a clinical and molecular description of bacteremia caused by ESBL-producing enterobacteria. We retrospectively studied the cases of bacteremia due to ESBL-producing Escherichia coli, Klebsiella pneumoniae and Proteus spp in adults admitted to a university hospital during the years 2004-2007. We reviewed the clinical records and antimicrobial susceptibility patterns. Molecular typing was performed by polymerase chain reaction and study of clonality by pulsed-field electrophoresis. We found a prevalence of 9.8% ESBL in enterobacteria causing bacteremia. Decreased susceptibility to quinolones and aminoglycosides was observed, without resistance to carbapenems. The predominant ESBL types were CTX-M (96%), TEM (62%) and GES (28%). 79% of the strains presented more than one type of ESBL. Clinical analysis revealed high prevalence of risk factors, previous use of antimicrobials and of invasive devices. There was no significant clonality. The presence of ESBLs in bloodstream infections is a clinical problem that must be considered when choosing empiric therapy.

DNA double-strand breaks induced by high NaCl occur predominantly in gene deserts

High concentration of NaCl increases DNA breaks both in cell culture and in vivo. The breaks remain elevated as long as NaCl concentration remains high and are rapidly repaired when the concentration is lowered. The exact nature of the breaks, and their location, has not been entirely clear, and it has not been evident how cells survive, replicate, and maintain genome integrity in environments like the renal inner medulla in which cells are constantly exposed to high NaCl concentration. Repair of the breaks after NaCl is reduced is accompanied by formation of foci containing phosphorylated H2AX (γH2AX), which occurs around DNA double-strand breaks and contributes to their repair. Here, we confirm by specific comet assay and pulsed-field electrophoresis that cells adapted to high NaCl have increased levels of double-strand breaks. Importantly, γH2AX foci that occur during repair of the breaks are nonrandomly distributed in the mouse genome. By chromatin immunoprecipitation using anti-γH2AX antibody, followed by massive parallel sequencing (ChIP-Seq), we find that during repair of double-strand breaks induced by high NaCl, γH2AX is predominantly localized to regions of the genome devoid of genes ("gene deserts"), indicating that the high NaCl-induced double-strand breaks are located there. Localization to gene deserts helps explain why the DNA breaks are less harmful than are the random breaks induced by genotoxic agents such as UV radiation, ionizing radiation, and oxidants. We propose that the universal presence of NaCl around animal cells has directly influenced the evolution of the structure of their genomes.

Molecular characteristics of extended-spectrum β-lactamase-producing Escherichia coli from Rio de Janeiro, Brazil

Twenty-five extended-spectrum β-lactamase (ESBL)-producing Escherichia coli clinical isolates from Rio de Janeiro, Brazil were characterized by isoelectric focusing, PCR and sequencing of blaESBL genes, plasmid-mediated quinolone resistance determinants, phylogenetic groups, replicon typing, pulsed-field electrophoresis, and multilocus sequencing typing. Twenty-three (92%) ESBL-producing E. coli isolates were positive for blaCTX-M genes, aac(6′)-Ib-cr, and qnrB. Genetic relatedness of ESBL producers clustered seven (28%) CTX-M-15-producing isolates as sequence type (ST)410, clonal complex (CC) 23, and two (8%) as clone O25-ST131. Our results illustrate the predominance of phylogroup A (52%), ST410 (CC 23) and CTX-M-15 among ESBL-producing E. coli isolates from hospitals in Rio de Janeiro.

Heterogeneity of methicillin-sensitive Staphylococcus pseudintermedius strains isolated from diseased dogs

Thirty nine canine S. pseudintermedius strains were examined for antibiotic susceptibility and genetic polymorphisms. All strains were methicillin-sensitive S. pseudintermedius (MSSP). Resistance to penicillin was most prevalent (66.6%), followed by resistance to neomycin (56.4%), erythromycin (53.8%), clindamycin (48.7%), chloramphenicol (48.7%), and tetracycline (46.2%). Pulsed-field electrophoresis (PFGE) showed a high genetic polymorphism in the investigated strains.

Alkylation Base Damage Is Converted into Repairable Double-Strand Breaks and Complex Intermediates in G2 Cells Lacking AP Endonuclease

DNA double-strand breaks (DSBs) are potent sources of genome instability. While there is considerable genetic and molecular information about the disposition of direct DSBs and breaks that arise during replication, relatively little is known about DSBs derived during processing of single-strand lesions, especially for the case of single-strand breaks (SSBs) with 3′-blocked termini generated in vivo. Using our recently developed assay for detecting end-processing at random DSBs in budding yeast, we show that single-strand lesions produced by the alkylating agent methyl methanesulfonate (MMS) can generate DSBs in G2-arrested cells, i.e., S-phase independent. These derived DSBs were observed in apn1/2 endonuclease mutants and resulted from aborted base excision repair leading to 3′ blocked single-strand breaks following the creation of abasic (AP) sites. DSB formation was reduced by additional mutations that affect processing of AP sites including ntg1, ntg2, and, unexpectedly, ogg1, or by a lack of AP sites due to deletion of the MAG1 glycosylase gene. Similar to direct DSBs, the derived DSBs were subject to MRX (Mre11, Rad50, Xrs2)-determined resection and relied upon the recombinational repair genes RAD51, RAD52, as well as on the MCD1 cohesin gene, for repair. In addition, we identified a novel DNA intermediate, detected as slow-moving chromosomal DNA (SMD) in pulsed field electrophoresis gels shortly after MMS exposure in apn1/2 cells. The SMD requires nicked AP sites, but is independent of resection/recombination processes, suggesting that it is a novel structure generated during processing of 3′-blocked SSBs. Collectively, this study provides new insights into the potential consequences of alkylation base damage in vivo, including creation of novel structures as well as generation and repair of DSBs in nonreplicating cells.

A specific inhibitor of protein kinase CK2 delays gamma-H2Ax foci removal and reduces clonogenic survival of irradiated mammalian cells

BackgroundThe protein kinase CK2 sustains multiple pro-survival functions in cellular DNA damage response and its level is tightly regulated in normal cells but elevated in cancers. Because CK2 is thus considered as potential therapeutic target, DNA double-strand break (DSB) formation and rejoining, apoptosis induction and clonogenic survival was assessed in irradiated mammalian cells upon chemical inhibition of CK2.MethodsMRC5 human fibroblasts and WIDR human colon carcinoma cells were incubated with highly specific CK2 inhibitor 4,5,6,7-tetrabromobenzotriazole (TBB), or mock-treated, 2 hours prior to irradiation. DSB was measured by pulsed-field electrophoresis (PFGE) as well as gamma-H2AX foci formation and removal. Apoptosis induction was tested by DAPI staining and sub-G1 flow cytometry, survival was quantified by clonogenic assay.ResultsTBB treatment did not affect initial DNA fragmention (PFGE; up to 80 Gy) or foci formation (1 Gy). While DNA fragment rejoining (PFGE) was not inhibited by the drug, TBB clearly delayed gamma-H2AX foci disappearence during postirradiation incubation. No apoptosis induction could be detected for up to 38 hours for both cell lines and exposure conditions (monotherapies or combination), but TBB treatment at this moderately toxic concentration of 20 μM (about 40% survival) enhanced radiation-induced cell killing in the clonogenic assay.ConclusionsThe data imply a role of CK2 in gamma-H2AX dephosporylation, most likely through its known ability to stimulate PP2A phosphatase, rather than DSB rejoining. The slight but definite clonogenic radiosensitization by TBB does apparently not result from interference with an apoptosis suppression function of CK2 in these cells but could reflect inhibitor-induced uncoupling of DNA damage response decay from break ligation.

Fission Yeast Pot1 and RecQ Helicase Are Required for Efficient Chromosome Segregation

Pot1 is a single-stranded telomere-binding protein that is conserved from fission yeast to mammals. Deletion of Schizosaccharomyces pombe pot1(+) causes immediate telomere loss. S. pombe Rqh1 is a homolog of the human RecQ helicase WRN, which plays essential roles in the maintenance of genomic stability. Here, we demonstrate that a pot1Δ rqh1-hd (helicase-dead) double mutant maintains telomeres that are dependent on Rad51-mediated homologous recombination. Interestingly, the pot1Δ rqh1-hd double mutant displays a "cut" (cell untimely torn) phenotype and is sensitive to the antimicrotubule drug thiabendazole (TBZ). Moreover, the chromosome ends of the double mutant do not enter the pulsed-field electrophoresis gel. These results suggest that the entangled chromosome ends in the pot1Δ rqh1-hd double mutant inhibit chromosome segregation, signifying that Pot1 and Rqh1 are required for efficient chromosome segregation. We also found that POT1 knockdown, WRN-deficient human cells are sensitive to the antimicrotubule drug vinblastine, implying that some of the functions of S. pombe Pot1 and Rqh1 may be conserved in their respective human counterparts POT1 and WRN.

Geographical and Temporal Dissemination of Salmonellae Isolated from Domestic Animal Hosts in the Culiacan Valley, Mexico

The prevalence and diversity of salmonellae from domestic animal hosts were investigated in the Culiacan Valley, Mexico. A total of 240 farm animal feces (cows, chicken, and sheep) were evaluated for Salmonella spp. presence from July 2008 to June 2009. Salmonella enterica subsp. enterica strains were isolated from 76 samples (31.7%), and 20 serotypes were identified being Salmonella Oranienburg (25%), Salmonella Give (14%), Salmonella Saintpaul (12%), and Salmonella Minnesota (11%) the most frequent isolates. Twenty-four percent (18/76) of the isolates were resistant to ampicillin. Salmonella Oranienburg, Salmonella Minnesota, Salmonella Give, Salmonella Agona, Salmonella Weltevreden, and Salmonella Newport serotypes showed multiple pulsed-field electrophoresis patterns. Salmonella Oranienburg was the dominant serotype in the Culiacan Valley; however, no specific distribution patterns were detected in animal sources or sampling sites. The genetic diversity of salmonellae could be an evidence of the continuous animal exposition to the bacteria. Also, Salmonella adaptation in asymptomatic animals could be justified by the development of natural host immunity. This study provides novel information about Salmonella population distribution in domestic animals living at tropical areas. The presence of asymptomatic carriers may be critical to understand the routes of transmission of Salmonella in areas of high disease prevalence.

Lethal and mutagenic interactions between γ-rays, cisplatin and etoposide at the cellular and molecular levels

Purpose: We analysed the lethal and mutagenic interactions between γ-rays, cisplatin (Pt) and etoposide (E), three agents used in tumour chemoradiotherapy. Corresponding results at cellular and molecular levels could provide additional elements on involved mechanisms and, on antitumour activity and toxicity in combined cancer treatments.Materials and methods: The yeast Saccharomyces cerevisiae SC7K(lys2–3) (auxotrophic for lysine) was used as eukaryotic model. Exponential growing cells were exposed to the mentioned agents, as single and combined treatments. Lethal and mutation interaction equations were determined as a function of doses according to quantitative models. DNA double-strand breaks were evaluated immediately after treatments, through pulsed-field electrophoresis and laser densitometry.Results: All three agents induced significant mutant frequency. The γ +Pt + E combination determined maximal lethal and mutagenic synergism, followed by γ + Pt and γ + E combinations. Meanwhile, Pt + E combination showed lethal additivity and very low mutagenic synergism. Pt + E double combination determined moderate DNA degradation. DNA degradation after γ-exposure, was similar to that of γ + Pt, γ + E and γ + Pt + E combinations.Conclusions: Synergistic lethal and mutagenic interactions indicate crosstalk between non-homologous end joining, homologous recombination and postreplicative repair pathways. Pt + E additivity indicate independence of involved repair pathways. Furthermore, the quantification of interactive events may be an additional suitable tool in tumour therapy planning.

Susceptibilidad antimicrobiana, serotipos capsulares y relación clonal entre cepas invasoras de Streptococcus pneumoniae aisladas de pacientes adultos de la Región del Bío-Bío, Chile: Período 2005-2006

Streptococcus pneumoniae infections constitute a public health problem. In our country there is scarce information regarding isolates from bacteraemic episodes in adult population. The antibiotic susceptibility, serotypes and clonal relationship of 56 isolates of S. pneumoniae from adult patients with bacteraemic infections in Concepcion-Talcahuano, Bio-Bio Region, Chile, were studied. Resistance to tetracycline (21.4%), trimethoprim/ sulfamethoxazole (18%), erythromycin (18%), chloramphenicol (7%) and 1 penicillin resistant isolate from a meningeal focus (2%) was found. Also, all the isolates were susceptible to cefotaxime, levofloxacin, moxifloxacin and vancomycin. A wide variety of capsular serotypes was demonstrated, with predominance of serotypes 1, 5, 23F, 7F and 3. The macrorestriction analysis by pulse field electrophoresis revealed 31 electrophoretic patterns and 12 clonal groups, discarding a predominant clone. According to the results, at least, 80% of the S. pneumoniae serotypes isolated from bacteraemic adult patients are included in the available commercial vaccine.

In this issue

PROTEOMICSVolume 10, Issue 18 In this issue In this issue First published: 02 September 2010 https://doi.org/10.1002/pmic.201090082AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Stroke: Rowing speed or brain stopper Olympic rowing teams have strokes. The rest of us have “ischemic events”. The brain's response over time to a brief blockage of circulation is the subject of interest to Costain et al. In particular, they are studying the proteomic response of synaptosomes to coronary occlusion. Using ICAT labeling and nanoLC-MS/MS, they compare proteomes of synaptosomes at 0, 3, 6, and 20 h of reperfusion after 1 h of focal ischemia. Not too surprisingly, most of the differentially regulated proteins were found to come from mitochondria. Total RNA isolated from the synaptosomes and quantitated by semi-qPCR demonstrated that the response was not transcriptionally regulated. Gene ontology was also examined. A significant regulatory system that was disrupted was the Psap conversion into four saposin activator proteins. pp. 3272–3291 Type II diabetes: Initial proteomic exploration of arterial effects If you are diagnosed with DBII you'll probably have trouble with atherosclerosis...or is it arteriosclerosis? It's almost for sure the latter, a combination of glycation of extracellular proteins, fiber growth in the middle layer of artery muscle, calcification and a variety of changes in the extracellular matrix. The changes lead to arterial inelasticity, wall thickening and stiffness of the medium and larger arteries. To get a better grasp on these events and effects, Jüllig et al. used proteomic techniques to compare arteries from rats with artificially induced diabetes and normal rats. Looking at approximately 400 proteins, they linked clusters of proteins to reactive oxygen species response and structure modification of myofibrils and microfilaments. They also found reduced levels of glycolytic enzymes and mitochondrial electron transport system components. pp. 3367–3378 Gels to the max: Blue Native Acrylamide Gel Electrophoresis hits >10 MDa Or should these be called “Pictish Gels” after those blue painted residents of northern Scotland who gave the Romans such a hard time at Hadrian's wall? In any case, Strecker et al. have begun the task of taming the high range of these gels and report here on gel formulations that separate mega-Dalton molecular weight proteins. In much the way pulsed field electrophoresis gave DNA researchers the ability to handle megabase-sized DNA molecules (once you worked out or found published protocols), BNE gels take us into the unexplored region of Mega-Da membrane and soluble proteins. At the moment, this is a “Bring Your Own Marker” space, waiting for someone to establish some ultrahigh MW markers' credibility by electron microscopy. But while waiting, these researchers are pushing onward with nuclear pores, mitochondrial complexes, respiratory strings, patches and more, just waiting for the electrophoretic buzz. pp. 3379–3387 Volume10, Issue18No. 18 September 2010 RelatedInformation

DNA Dynamics in Nanoscale Confinement under Asymmetric Pulsed Field Electrophoresis

DNA Dynamics in Nanoscale Confinement under Asymmetric Pulsed Field Electrophoresis

DNA Dynamics in Nanoscale Confinement under Asymmetric Pulsed Field Electrophoresis

Unbending: Asymmetric pulsed field electrophoresis of DNA was conducted in a nanoporous array formed by colloidal self-assembly of nanoparticles inside a microfluidic system. In confinement smaller than the persistence length of DNA molecules, DNA is maintained in highly stretched conformation. A model correlating pulse frequency, electric field, and molecular size with the observed angular dispersion was developed and experimentally verified.

Une maladie d’actualité en production aviaire : la colibacillose

Les colibacilloses aviaires sont une pathologie fréquente conduisant à de nombreux traitements antibiotiques avec les risques d’émergence de résistance. Bien que limité, le risque zoonosique est décrit et nous confirmons l’augmentation de la prévalence de la colibacillose aviaire dans les élevages de l’Ouest, en 2009. Il est important de différencier les souches de colibacilles commensales des souches pathologiques et de comprendre leur épidémiologie. Les outils de la biologie moléculaire tels que l’amplification des facteurs de virulence par la réaction en chaîne par polymérase (PCR) et l’électrophorèse en champ pulsé, nous ont permis de caractériser précisément les souches ; les résultats amènent des hypothèses sur les modalités de la transmission des colibacilles. Si celle de la transmission verticale se confirmait, il faudrait envisager des méthodes de prévention efficaces, notamment par la vaccination.

L’histoire de Staphylococcus aureus ST398 : un paradigme médical du 21ème siècle

Staphylococus Aureus ST 398 : a medical paradigm of the 21st century. The potential for nasal and pharyngeal colonization by the bacterial species, Staphylococcus aureus, has increased over the last decade, particularly among pigs. The frequency of Methicillin-Resistant Staphylococcus aureus (MRSA) strains varies, but they constitute a non-negligible risk for those involved in pig production, i. e. pig-keepers, veterinarians, and slaughterhouse workers. Molecular identification by MLST (Multi Locus Sequence Typing) of isolates originally non-typeable (NT) by Pulse Field Electrophoresis clearly showed the predominance in Europe, North America and Asia of the ST398 (CC398) type. So far, this strain does not appear to be highly resistant to antibiotics, with the exception of tetracyclines, and perhaps macrolides, nor does it produce the virulence factors generally associated with CA-MRSA, such as the Panton-Valentine leukocidin. Various types of human infection were reported in several European countries, producing skin and mucous membranes, lungs, endocardium and bacteremic infections. Some experts suggest that, despite their low risk of spreading to humans, these LA (Livestock-Associated) isolates may lead to «a new zoonosis» .