Antimicrobial Drug Resistance and Molecular Typing of Salmonella enterica Serovar Rissen from Different Sources.

Salmonella enterica serovar Rissen is one of the most common serovars found in pigs and pork products in different countries, including Spain. However, information on the molecular bases of antimicrobial drug resistance and the population structure of Salmonella Rissen from different sources in Spain is limited. The present study focused on 84 isolates collected in Spain from pig and beef carcasses, foods and clinical samples associated with sporadic cases of gastroenteritis, and one outbreak.

Metal-Organic Framework (MOF) Defects under Control: Insights into the Missing Linker Sites and Their Implication in the Reactivity of Zirconium-Based Frameworks.

For three-dimensional (3D) metal-organic frameworks (MOFs), the presence and nature of structural defects has been recognized as a key factor shaping the material's physical and chemical behavior. In this work, the formation of the "missing linker" defects has been addressed in the model biphenyl-4,4'-dicarboxylate (bpdc)-based Zr MOF, UiO-67. The defect showed strong dependence on the nature of the modulator acid used in the MOF synthesis; the defects, in turn, were found to correlate with the MOF physical and chemical properties.

In situ surface coverage analysis of RuO2-catalysed HCl oxidation reveals the entropic origin of compensation in heterogeneous catalysis.

In heterogeneous catalysis, rates with Arrhenius-like temperature dependence are ubiquitous. Compensation phenomena, which arise from the linear correlation between the apparent activation energy and the logarithm of the apparent pre-exponential factor, are also common. Here, we study the origin of compensation and find a similar dependence on the rate-limiting surface coverage term for each Arrhenius parameter.

Genotypes, exotoxin gene content, and antimicrobial resistance of Staphylococcus aureus strains recovered from foods and food handlers.

Staphylococcal food poisoning, one of the most common food-borne diseases, results from ingestion of one or more staphylococcal enterotoxins (SEs) produced by Staphylococcus aureus in foods. In the present study, 64 S. aureus isolates recovered from foods and food handlers, associated or not associated with food-poisoning outbreaks in Spain, were investigated.

[Outbreak of gastroenteritis in a nursery school caused by a strain of Salmonella enterica serovar Typhimurium carrying the hybrid virulence-resistance plasmid pUO-StVR2].

Objective: Epidemiological and microbiological study of a salmonellosis outbreak, affecting 22 children in a nursery school in Oviedo (Spain).

Methods: Attack rates and epidemic curves were determined, and bacterial typing methods were applied.

Results: The outbreak was attributed to a Salmonella enterica serovar Typhimurium strain, belonging to an emergent type characterized by the presence of a hybrid virulence-resistance plasmid of 125-130 kb, named pUO-StVR2.

Molecular epidemiology of emergent multidrug-resistant Salmonella enterica serotype Typhimurium strains carrying the virulence resistance plasmid pUO-StVR2.

Objectives: To evaluate the incidence of a distinct multidrug-resistant (MDR) grouping of Salmonella serotype Typhimurium strains carrying the hybrid virulence resistance plasmid pUO-StVR2, and its possible evolution in the region where it was first detected [Principality of Asturias (PA), Spain].

Methods: pUO-StVR2-containing isolates were tentatively identified by two genetic markers: the bla(OXA-30) gene and the class 1 integron InH:2000 bp/bla(OXA-30)-aadA1a. Positive isolates were examined for resistance profile (RP), plasmid content, virulence profile (VP) and genomic polymorphisms using macrorestriction-PFGE.

Genetic basis of antimicrobial drug resistance in clinical isolates of Salmonella enterica serotype Hadar from a Spanish region.

The genetic bases of antimicrobial drug resistance (R) of 79 Salmonella enterica serotype Hadar clinical isolates (recovered during 1995-2001 in a Spanish region) was investigated. The isolates showed a limited genomic variation, as demonstrated by PFGE analysis using XbaI (three profiles, S>or=0.77) and BlnI (seven profiles, S>or=0.

Genetic procedures for identification of enterotoxigenic strains of Staphylococcus aureus from three food poisoning outbreaks.

Three food poisoning restaurant outbreaks due to Staphylococcus aureus, occurring during June-October 2002 in the Principality of Asturias (PA), Spain, provided the basis for investigating some aspects of the molecular epidemiology of this organism. The methods applied to identify strains and lineages included multiplex-polymerase chain reaction (PCR) to detect nine enterotoxin (se) genes, and three DNA fingerprinting procedures: pulsed-field gel electrophoresis (PFGE) with SmaI, randomly amplified polymorphic DNA (RAPD) with two selected primers, and plasmid restriction analysis with HindIII. Thirty-two isolates were differentiated into three non-se and 12 se strains, which were outbreak-specific, except for one that was represented in two of the outbreaks.

Antimicrobial resistance in clinical isolates of Salmonella enterica serotype Enteritidis: relationships between mutations conferring quinolone resistance, integrons, plasmids and genetic types.

In 481 clinical isolates of Salmonella enterica serotype Enteritidis collected from a Spanish region in 2000, 108, 83 and four isolates were resistant, respectively, to nalidixic acid, ampicillin or both. Nalidixic acid resistance was the result of DNA gyrase mutations involving the codons Asp-87 (97 isolates) and Ser-83 (15 isolates) of the gyrA gene; no mutations in parC were detected. In ampicillin-resistant strains, blaTEM genes located on plasmids and/or the chromosome were implicated.

Outbreaks and sporadic cases of Salmonella serovar panama studied by DNA fingerprinting and antimicrobial resistance.

In the Principality of Asturias (PA), Spain. three Salmonella serovar Panama outbreaks were registered in August 1998. In order to achieve an accurate identification of the strains implicated in the outbreaks and to study the molecular epidemiology of this serovar in the PA, the isolates collected over 1990-1999 were examined by DNA fingerprinting and antimicrobial resistance analysis.

Enterotoxin production and DNA fingerprinting in Staphylococcus aureus isolated from human and food samples. Relations between genetic types and enterotoxins.

A total of 224 Staphylococcus aureus strains from human carriers (110 strains) and manually handled foods (114 strains) collected in the Principality of Asturias, Spain over 1995-1999 were analysed for the production of enterotoxins (SEs) A, B, C, and D by a reversed passive latex agglutination test and by amplification of ent genes (A, B, C, D, E, and J) using PCR. Sixty-two strains were enterotoxigenic and a good relation between detection of SEs and their ent genes was found. No strain carried entE and all strains producing SED carried entD and entJ genes.

Usefulness of genetic typing methods to trace epidemiologically Salmonella serotype Ohio.

Different genetic typing procedures were applied in an epidemiological study of Salmonella serotype Ohio. Isolates that generated identical DNA fingerprints (HinclI ribotypes, ERIC and RAPD profiles) were clustered into the same lineage, and the addition of data from plasmid, integron and resistance profiles was used to differentiate types. Results led to the determination of the endemic and the emergent epidemic types at specific times, and to ascertain the clinical and epidemiological impact of each type.

Molecular characterisation of emergent multiresistant Salmonella enterica serotype [4,5,12:i:-] organisms causing human salmonellosis.

Salmonella multidrug-resistant clinical organisms identified as serotype [4,5,12:i:-] were typed using selected genetic procedures and compared with typhimurium organisms collected in the same Spanish region. Results showed a low genetic heterogeneity among [4,5,12:i:-] organisms, which generated identical ribotypes and similar but not identical XbaI PFGE, RAPD, and plasmid profiles. Multidrug resistance could be eliminated by curing and seems to be mediated by 140-kb (spvC+) and 120-kb (spvC-) non-self-transferable plasmids.

Potential of three-Way randomly amplified polymorphic DNA analysis as a typing method for twelve Salmonella serotypes.

The potential of a three-way randomly amplified polymorphic DNA (RAPD) procedure (RAPD typing) for typing Salmonella enterica strains assigned to 12 serotypes was analyzed. The series of organisms used included 235 strains (326 isolates) collected mainly from clinical samples in the Principality of Asturias and 9 reference strains. RAPD typing was performed directly with broth cultures of bacteria by using three selected primers and optimized PCR conditions.

[Salmonella and salmonellosis in the Asturias District, Spain, during a seven year period (1990-1996)].

Background: Retrospective study of the Salmonella sp. strains and human salmonellosis episodes registered in the Public Health Laboratory of the Principado de Asturias, Spain, over the seven year period 1990-1996.

Material And Methods: All strains were serotyped; strains of serotypes Typhi and Typhimurium were also phage typed.

Genetic heterogeneity of clinical strains of Yersinia enterocolitica traced by ribotyping and relationships between ribotypes, serotypes, and biotypes.

A series of 74 Yersinia enterocolitica clinical strains collected in a Spanish region and 10 reference strains, assigned to nine serotypes and five biotypes, were analyzed by ribotyping procedures. Riboprobing, performed separately with HindIII and BglI and using an rrn operon as the probe, generated 13 and 11 ribotypes (discrimination index [DI] = 0.56 and 0.

Molecular epidemiology of Salmonella serotype Enteritidis. Relationships between food, water and pathogenic strains.

A molecular epidemiology study of Salmonella serotype Enteritidis was carried out by ribotyping performed with a mixture of PstI and SphI (PS ribotyping), and randomly amplified polymorphic DNA (RAPD) typing conducted with the OPB17 primer. A series, including 38 food and 25 water strains, which were epidemiologically unrelated and collected in Spain over 1985-1996, was differentiated into 20 PS ribotypes [discrimination index (DI) = 0.67], RAPD types (DI = 0.

Genetic typing methods applied to the differentiation of clonal lines among Salmonella enterica serogroup G strains causing human salmonellosis.

In Spain, in November 1995, an epidemiological alert recommended the surveillance of Salmonella serogroup G. The nine clinical isolates collected after and the four collected before the alert in Asturias were differentiated into six clonal lines by the combination of results from HincII ribotyping, PCR ribotyping, and RAPD typing using primers named A and S. The seven Gumpensis isolates showed identical DNA fingerprinting with the four typing procedures falling into a line.

A three-way ribotyping scheme for Salmonella serotype Typhimurium and its usefulness for phylogenetic and epidemiological purposes.

Ribotyping of Salmonella serotype Typhimurium strains was optimised as a tool for epidemiological and phylogenetic purposes. Of five restriction endonucleases evaluated on a series of 84 isolates, HincII, SalI and PvuII were the most useful, generating 13, 9 and 9 ribotypes with 17, 11 and 18 polymorphic restriction sites, and attaining a discrimination index (DI) of 0.81, 0.

Epidemiological differentiation of pathogenic strains of Salmonella enteritidis by ribotyping.

The usefulness of two-way ribotyping, performed with SphI and PstI, as a genetic marker for a series of pathogenic Salmonella enteritidis strains is reported. Eighteen combined ribotypes were differentiated, a discrimination index of 0.77 was reached, a genetic relationship dendrogram was traced, and the results were applied in an epidemiological study.

Diagnosis by a Combination of Typing Methods of a Salmonella typhimurium Outbreak Associated with Cured Ham.

This paper describes the usefulness of combining typing methods (antibiotyping, phage typing, plasmid profile, and ribotyping) in the characterization of a Salmonella enterica serotype Typhimurium ( S. typhimurium ) strain as the causal agent of an outbreak associated with cured ham, Serrano variety, which is an unusual infection source of Salmonella . Human isolates and the majority of ham isolates showed identical biochemical profiles, antibiotypes, plasmid profiles, and ribotypes.

Usefulness of ribotyping in a molecular epidemiology study of shigellosis.

Ribotyping performed with six restriction endonucleases was used to study the molecular epidemiology of shigellosis in Asturias, Spain. The series included Shigella sonnei from 34 sporadic cases, 3 outbreaks and 3 reference strains, and S. Flexneri from sporadic cases and 1 reference strain.

Discriminatory power and application of ribotyping of Yersinia enterocolitica O:3 in an epidemiological study.

Ribotyping performed with five restriction endonucleases was used in an attempt to subtype Yersinia enterocolitica serotype O:3 and also as a tool for clonal analysis. DNA from organisms under study (48 isolates from diarrheic human feces, 24 from food, and 5 reference strains) was tested by Southern hybridization using a DNA probe carrying an rRNA operon from Escherichia coli. Strains were grouped into seven ribotypes by the HindIII restriction endonuclease, into five ribotypes by Ncil, Bg/l, and Sa/l; and into two ribotypes by EcoRI, resulting in a discrimination index (DI) of 0.

Polymorphism of rRNA genes and plasmid analysis in the typing of Salmonella enterica serovar enteritidis from a Spanish health area.

A molecular epidemiological study of Salmonella enterica serovar Enteritidis (S. enteritidis) in a Spanish Health Area was carried out using two genotypic methods; polymorphism of rRNA genes (ribotyping) and plasmid analysis. The series included 100 isolates randomly selected from among those collected over the period 1984-92 (50 from sporadic episodes and 50 from 10 outbreaks).

Differentiation of strains from a food-borne outbreak of Salmonella enterica by phenotypic and genetic typing methods.

A combination of typing methods was used to identify the strains and the infection source in a food-borne outbreak of Salmonella enterica occurring in a summer camp and affecting 25 children. All isolates tested were found to be serovar Enteritidis, with an identical biotype API 20E and ribotype. However, they differed in their plasmid profiles and/or antibiograms, and were grouped into three strains.