Search

Paratyphoid B fever (PTB) is caused by an invasive lineage (phylogroup 1, PG1) of Salmonella enterica serotype Paratyphi B (SPB). However, little was known about the global population structure, geographic distribution, and evolution of this pathogen. Here, we report a whole-genome analysis of 568 historical and contemporary SPB PG1 isolates, obtained globally, between 1898 and 2021. We show that this pathogen existed in the 13th century, subsequently diversifying into 11 lineages and 38 genotypes with strong phylogeographic patterns. Following its discovery in 1896, it circulated across Europe until the 1970s, after which it was mostly reimported into Europe from South America, the Middle East, South Asia, and North Africa. Antimicrobial resistance recently emerged in various genotypes of SPB PG1, mostly through mutations of the quinolone-resistance-determining regions of gyrA and gyrB. This study provides an unprecedented insight into SPB PG1 and essential genomic tools for identifying and tracking this pathogen, thereby facilitating the global genomic surveillance of PTB., Competing Interests: Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Salmonella Paratyphi B infections in England are the least common imported typhoidal infection but can still cause invasive disease. Sentinel surveillance at the reference laboratory detected an outbreak from Iraq due to reported travel history, enabling enhanced PCR testing for a quick diagnosis.

Background: Salmonella Paratyphi B (Paratyphoid B) is a rare infection and a notifiable disease in England. Disease is typically mild, and chronic carriage in children has been described in endemic countries. Almost all cases in England are imported, with very few cases of community transmission reported., Methods: The aim of this work was to describe an unusual cluster of Paratyphoid B cases transmitted within England, examining clinical, epidemiologic and microbiologic data. Detailed phylogenetic analysis is presented to corroborate public health epidemiologic links between cases., Results: One child had recently returned from an endemic area and had mild gastrointestinal symptoms. One year later, 2 other children with no travel history developed invasive disease requiring hospitalization. Epidemiologic links confirmed person-to-person spread between these three cases. All isolates of S. Paratyphi B (n = 93) received by the Gastrointestinal Bacteria Reference Unit between 2014 and 2019 were typed using whole genome sequencing. Three cases of Paratyphoid B were identified in the same geographical location over a 2-year period. S. Paratyphi B strains isolated from the stool and blood of the three cases were closely linked (0-5 single-nucleotide polymorphisms) using whole genome sequencing., Conclusions: This case series highlights the potential public health risks of paratyphoid B and the range of pediatric complications associated with this illness, especially in younger children. Although rare, chronic carriage of Paratyphoid B can lead to transmission in nonendemic areas and should be considered in all children presenting with signs of enteric fever even where there is no history of foreign travel., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Salmonellosis is an important worldwide food-borne disease. Increasing resistance to Salmonella spp. has been reported in recent years, and now the prevalence of multidrug-resistant Salmonella spp. is a worldwide problem. This necessitates alternative approaches like phage therapy. This study aimed to isolate bacteriophages specific for Salmonella enterica serovar Paratyphi B and S. enterica serovar Typhimurium isolated from different sources (chicken meat, beef and eggshells). The antibiotic resistance profiles of the bacteria were determined by phenotypic and genotypic methods. The prevalence of extended-spectrum β-lactamase genes was examined by polymerase chain reaction. In total, 75% of the isolated Salmonella strains were resistant to tetracycline, whereas 70% of them were resistant to azithromycin. All of the isolates from beef were resistant to nalidixic acid. The most common extended-spectrum β-lactamase genes among the isolates were blaSHV (15%) followed by blaTEM (10%) and blaCTX (5%). Two specific bacteriophages were isolated and characterized. The host range for vB_SparS-ui was Salmonella Paratyphi B, S. enterica serovar Paratyphi A and S. enterica, while that for vB_StyS-sam phage was Salmonella Typhimurium and S. enterica serovar Enteritidis. The characteristics of the isolated phages indicate that they are proper candidates to be used to control some foodstuff contaminations and also phage therapy of infected animals., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS.)

Salmonella enterica serovar Paratyphi B variant Java sequence type 28 is prevalent in poultry and poultry meat. We investigated the evolutionary relatedness between sequence type 28 strains from Europe and Latin America using time-resolved phylogeny and principal component analysis. We sequenced isolates from Colombia, Guatemala, Costa Rica, and the Netherlands and complemented them with publicly available genomes from Europe, Africa, and the Middle East. Phylogenetic time trees and effective population sizes (N e ) showed separate clustering of strains from Latin America and Europe. The separation is estimated to have occurred during the 1980s. N e of strains increased sharply in Europe around 1995 and in Latin America around 2005. Principal component analysis on noncore genes showed a clear distinction between strains from Europe and Latin America, whereas the plasmid gene content was similar. Regardless of the evolutionary separation, similar features of resistance to β-lactams and quinolones/fluoroquinolones indicated parallel evolution of antimicrobial resistance in both regions.

Salmonella enterica serovar Paratyphi B (S. Paratyphi B) is a major foodborne pathogen distributed all over the world. However, little is known about the antibiotic resistance, genetic relatedness and virulence profile of S. Paratyphi B isolated from leafy vegetables and the processing environment in Malaysia. In this study, 6 S. Paratyphi B isolates were recovered from different vegetables and drain water of processing areas obtained from fresh food markets in Malaysia. The isolates were characterized by antibiogram, Pulsed-field gel electrophoresis (PFGE) and virulence genes. Antibiotic susceptibility test showed that 3 of the isolates were resistant to the antibiotics. These include S. Paratyphi B SP251 isolate, which was resistant to chloramphenicol, ampicillin, sulfonamides and streptomycin; Isolate SP246 which was resistant to chloramphenicol, sulfonamides and streptomycin and Isolate SP235 showing resistance to nalidixic acid only. PFGE subtyped the 6 S. Paratyphi B isolates into 6 distinct XbaI-pulsotypes, with a wide range of genetic similarity (0.55 to 0.9). The isolates from different sources and fresh food markets location were genetically diverse. Thirteen (tolC, orgA, spaN, prgH, sipB, invA, pefA, sofB, msgA, cdtB, pagC, spiA and spvB) out of the 17 virulence genes tested were found in all of the S. Paratyphi B isolates. Another gene (lpfC), was found only in one isolate (SP051). None of the isolates possessed sifA, sitC and ironN genes. In summary, this study provides unique information on antibiotic resistance, genetic relatedness, and virulotyping of S. Paratyphi B isolated from leafy vegetables and processing environment., (Copyright © 2018. Published by Elsevier B.V.)

Enteric fever is caused by three Salmonella enterica serovars: Typhi, Paratyphi A, and Paratyphi B sensu stricto Although vaccines against two of these serovars are licensed (Typhi) or in clinical development (Paratyphi A), as yet there are no candidates for S. Paratyphi B. To gain genomic insight into these serovars, we sequenced 38 enteric fever-associated strains from Chile and compared these with reference genomes. Each of the serovars was separated genomically based on the core genome. Genomic comparisons identified loci that were aberrant between serovars Paratyphi B sensu stricto and Paratyphi B Java, which is typically associated with gastroenteritis; however, the majority of these were annotated as hypothetical or phage related and thus were not ideal vaccine candidates. With the genomic information in hand, we engineered a live attenuated S. Paratyphi B sensu stricto vaccine strain, CVD 2005, which was capable of protecting mice from both homologous challenge and heterologous challenge with S. Paratyphi B Java. These findings extend our understanding of S. Paratyphi B and provide a viable vaccine option for inclusion in a trivalent live attenuated enteric fever vaccine formulation. IMPORTANCE We developed a live attenuated Salmonella enterica serovar Paratyphi B vaccine that conferred protection in mice against challenge with S Paratyphi B sensu stricto and S Paratyphi B Java, which are the causes of enteric fever and gastroenteritis, respectively. Currently, the incidence of invasive S. Paratyphi B sensu stricto infections is low; however, the development of new conjugate vaccines against other enteric fever serovars could lead to the emergence of S. Paratyphi B to fill the niche left by these other pathogens. As such, an effective S. Paratyphi B vaccine would be a useful tool in the armamentarium against Salmonella infections. Comparative genomics confirmed the serovar-specific groupings of these isolates and revealed that there are a limited number of genetic differences between the sensu stricto and Java strains, which are mostly hypothetical and phage-encoded proteins. The observed level of genomic similarity likely explains why we observe some cross-protection., (Copyright © 2018 Higginson et al.)

Competing Interests: No conflicts of interest were reported.

Objectives: Plasmid-mediated mobilized colistin resistance is currently known to be caused by phosphoethanolamine transferases termed MCR-1, MCR-2, MCR-3 and MCR-4. However, this study focuses on the dissection of a novel resistance mechanism in mcr-1-, mcr-2- and mcr-3-negative d-tartrate fermenting Salmonella enterica subsp. enterica serovar Paratyphi B (Salmonella Paratyphi B dTa+) isolates with colistin MIC values >2 mg/L., Methods: A selected isolate from the strain collection of the German National Reference Laboratory for Salmonella was investigated by WGS and bioinformatical analysis to identify novel phosphoethanolamine transferase genes involved in colistin resistance. Subsequently PCR screening, S1-PFGE and DNA-DNA hybridization were performed to analyse the prevalence and location of the identified mcr-5 gene. Cloning and transformation experiments in Escherichia coli DH5α and Salmonella Paratyphi B dTa+ control strains were carried out and the activity of MCR-5 was determined in vitro by MIC testing., Results: In this study, we identified a novel phosphoethanolamine transferase in 14 mcr-1-, mcr-2- and mcr-3-negative Salmonella Paratyphi B dTa+ isolates with colistin MIC values >2 mg/L that were received during 2011-13. The respective gene, further termed as mcr-5 (1644 bp), is part of a 7337 bp transposon of the Tn3 family and usually located on related multi-copy ColE-type plasmids. Interestingly, in one isolate an additional subclone with a chromosomal location of the mcr-5 transposon was observed., Conclusions: Our findings suggest that the transfer of colistin-resistance-mediating phosphoethanolamine transferase genes from bacterial chromosomes to mobile genetic elements has occurred in multiple independent events raising concern regarding their variety, prevalence and impact on public health., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Unlabelled: For 100 years, it has been obvious that Salmonella enterica strains sharing the serotype with the formula 1,4,[5],12:b:1,2-now known as Paratyphi B-can cause diseases ranging from serious systemic infections to self-limiting gastroenteritis. Despite considerable predicted diversity between strains carrying the common Paratyphi B serotype, there remain few methods that subdivide the group into groups that are congruent with their disease phenotypes. Paratyphi B therefore represents one of the canonical examples in Salmonella where serotyping combined with classical microbiological tests fails to provide clinically informative information. Here, we use genomics to provide the first high-resolution view of this serotype, placing it into a wider genomic context of the Salmonella enterica species. These analyses reveal why it has been impossible to subdivide this serotype based upon phenotypic and limited molecular approaches. By examining the genomic data in detail, we are able to identify common features that correlate with strains of clinical importance. The results presented here provide new diagnostic targets, as well as posing important new questions about the basis for the invasive disease phenotype observed in a subset of strains., Importance: Salmonella enterica strains carrying the serotype Paratyphi B have long been known to possess Jekyll and Hyde characteristics; some cause gastroenteritis, while others cause serious invasive disease. Understanding what makes up the population of strains carrying this serotype, as well as the source of their invasive disease, is a 100-year-old puzzle that we address here using genomics. Our analysis provides the first high-resolution view of this serotype, placing strains carrying serotype Paratyphi B into the wider genomic context of the Salmonella enterica species. This work reveals a history of disease dating back to the middle ages, caused by a group of distinct lineages with various abilities to cause invasive disease. By quantifying the key genomic differences between the invasive and noninvasive populations, we are able to identify key virulence-related targets that can form the basis of simple, rapid, point-of-care tests., (Copyright © 2016 Connor et al.)

Background: We describe the antimicrobial susceptibility pattern of 100 typhoidal Salmonella isolates recovered from blood cultures and also investigate the association of decreased ciprofloxacin susceptibility with mutations in the genes coding for DNA gyrase and topoisomerase IV in 55 isolates., Methods: The study was conducted between January 2013 and December 2015 at a tertiary care centre in north India. Antimicrobial susceptibility testing was performed by Kirby-Bauer disc diffusion and E-test. Genotypic characterization included the screening of mutations in the quinolone resistance-determining region of gyrA, gyrB, parC, and parE by PCR. DNA sequence analysis was done for 55 isolates., Results: Out of 100 isolates recovered 80 were S. Typhi, 18 were Paratyphi A and two were Paratyphi B. Eighty two percent (66/80) of S. Typhi and 15/18 S. Paratyphi A showed decreased ciprofloxacin susceptibility. The most common mutation in gyrA led to a change at codon 83 of serine to phenylalanine (n=37) or tyrosine (n=12). Five S. Typhi isolates that were resistant to ciprofloxacin (MICs of 12, 16, 24 and 32 μg/ml) had a second mutation at codon 87 in the gyrA gene changing aspartate to asparagine., Conclusions: There is a need to urgently review the use of fluoroquinolones for the management of enteric fever in endemic areas., (© The Author 2016. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Salmonella Paratyphi B dT+ variant (also termed Salmonella Java) and Salmonella Heidelberg are pathogens of public health importance that are frequently isolated from poultry. As a step toward implementing the Colombian Integrated Program for Antimicrobial Resistant Surveillance, this study characterized molecular patterns of Salmonella Paratyphi B dT+ and Salmonella Heidelberg isolated from poultry farms, fecal samples, and retail chicken meat using pulsed-field gel electrophoresis (PFGE). The objective of this study was to determine the genetic relationship among isolates and to determine potential geographically predominant genotypes. Based on PFGE analysis, both serovars exhibited high heterogeneity: the chromosomal DNA fingerprints of 82 Salmonella Paratyphi B dT+ isolates revealed 42 PFGE patterns, whereas the 21 isolates of Salmonella Heidelberg revealed 10 patterns. Similar genotypes of both serovars were demonstrated to be present on farms and in retail outlets. For Salmonella Paratyphi B dT+, closely genetically related strains were found among isolates coming from different farms and different integrated poultry companies within two departments (Santander and Cundinamarca) and also from farms located in the two geographically distant departments. For Salmonella Heidelberg, there were fewer farms with genetically related isolates than for Salmonella Paratyphi B dT+. A possible dissemination of similar genotypes of both serovars along the poultry production chain is hypothesized, and some facilitating factors existing in Colombia are reviewed.

Salmonella enterica serotype Paratyphi B is a globally distributed human-specific pathogen causing paratyphoid fever. The aim of this study was to develop a rapid and reliable polymerase chain reaction (PCR) assay for its detection in food. The SPAB_01124 gene was found to be unique to S. Paratyphi B using comparative genomics. Primers for fragments of the SPAB_01124 gene and the Salmonella-specific invA gene were used in combination to establish a multiplex PCR assay that showed 100% specificity across 45 Salmonella strains (representing 34 serotypes) and 18 non-Salmonella strains. The detection limit was 2.2 CFU mL(-1) of S. Paratyphi B after 12-h enrichment in pure culture. It was shown that co-culture with S. Typhimurium or Escherichia coli up to concentrations of 3.6 × 10(5)  CFU and 3.3 × 10(4)  CFU, respectively, did not interfere with PCR detection of S. Paratyphi B. In artificially contaminated milk, the assay could detect as few as 62 CFU mL(-1) after 8 h of enrichment. In conclusion, comparative genomics was found to be an efficient approach to the mining of pathogen-specific target genes, and the PCR assay that was developed from this provided a rapid, specific, and sensitive method for detection of S. Paratyphi B., (© 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.)

Objectives: To characterize the genetic determinants responsible for extended-spectrum cephalosporin (ESC) resistance of d-tartrate-positive Salmonella enterica subsp. enterica serovar Paratyphi B (serovar Paratyphi B dT+) strains that have emerged in poultry and humans in Belgium during 2008-10., Methods: The ESC resistance genes among non-redundant serovar Paratyphi B dT+ strains were determined using PCR and sequencing. ESC phenotypes were horizontally transferred by conjugation. Extended-spectrum β-lactamase (ESBL)- or AmpC-carrying plasmids were typed by PCR-based replicon typing, plasmid multilocus sequence typing and restriction fragment length polymorphism. The genetic relationship of ESC-resistant strains was assessed by XbaI PFGE and multilocus sequence typing., Results: Since 2008, the proportion of serovar Paratyphi B dT+ strains from broiler origin has increased significantly to reach 36.5% in 2010. Among 95 non-duplicate serovar Paratyphi B dT+ strains, 35% were resistant to ESCs. At the same time, a few ESC-resistant serovar Paratyphi B dT+ strains from humans were also detected in Belgium. The most prevalent ESBL gene, blaCTX-M-1, and the AmpC cephalosporinase gene blaCMY-2 were identified on various conjugative IncI1 plasmids of different sequence types and with different additional non-β-lactam phenotypes. Interestingly, the blaCTX-M-2 gene was located on large multireplicon IncHI2/P plasmids. In addition, highly ESC-resistant strains contained both the ESBL CTX-M-2 and the AmpC CMY-2 encoded by the IncHI2/P and IncI1 plasmids, respectively. All ESC-resistant serovar Paratyphi B dT+ strains belonged to sequence type 28 and showed the common PFGE pattern X8, as well as the chromosomal class 2 integron cassette array dfrA1-sat2-aadA1 previously described in the European poultry-associated serovar Paratyphi B dT+ clonal population., Conclusions: This study showed that the clonal population of multidrug-resistant serovar Paratyphi B dT+, persisting in broilers in Belgium for the last decade, recently acquired various plasmid-borne ESC resistance determinants, constituting a major concern for public health. Further surveillance programmes and research are an absolute necessity to understand their epidemiology and to propose interventions to limit the spread of ESC- and multidrug-resistant Salmonella spp.

In this study, the population structure, incidence, and potential sources of human infection caused by the d-tartrate-fermenting variant of Salmonella enterica serovar Paratyphi B [S. Paratyphi B (dT+)] was investigated. In Germany, the serovar is frequently isolated from broilers. Therefore, a selection of 108 epidemiologically unrelated S. enterica serovar Paratyphi B (dT+) strains isolated in Germany between 2002 and 2010 especially from humans, poultry/poultry meat, and reptiles was investigated by phenotypic and genotypic methods. Strains isolated from poultry and products thereof were strongly associated with multilocus sequence type ST28 and showed antimicrobial multiresistance profiles. Pulsed-field gel electrophoresis XbaI profiles were highly homogeneous, with only a few minor XbaI profile variants. All strains isolated from reptiles, except one, were strongly associated with ST88, another distantly related type. Most of the strains were susceptible to antimicrobial agents, and XbaI profiles were heterogeneous. Strains isolated from humans yielded seven sequence types (STs) clustering in three distantly related lineages. The first lineage, comprising five STs, represented mainly strains belonging to ST43 and ST149. The other two lineages were represented only by one ST each, ST28 and ST88. The relatedness of strains based on the pathogenicity gene repertoire (102 markers tested) was mostly in agreement with the multilocus sequence type. Because ST28 was frequently isolated from poultry but rarely in humans over the 9-year period investigated, overall, this study indicates that in Germany S. enterica serovar Paratyphi B (dT+) poses a health risk preferentially by contact with reptiles and, to a less extent, by exposure to poultry or poultry meat.

Serotyping is not sufficient to differentiate between Salmonella species that cause paratyphoid fever from the strains that cause milder gastroenteritis as these organisms share the same serotype Salmonella Paratyphi B (S. Paratyphi B). Strains causing paratyphoid fever do not ferment d-tartrate and this key feature was used in this study to determine the prevalence of these strains among the collection of S. Paratyphi B strains isolated from patients in Malaysia. A total of 105 isolates of S. Paratyphi B were discriminated into d-tartrate positive (dT+) and d-tartrate negative (dT) variants by two lead acetate test protocols and multiplex PCR. The lead acetate test protocol 1 differed from protocol 2 by a lower inoculum size and different incubation conditions while the multiplex PCR utilized 2 sets of primers targeting the ATG start codon of the gene STM3356. Lead acetate protocol 1 discriminated 97.1% of the isolates as S. Paratyphi B dT+ and 2.9% as dT while test protocol 2 discriminated all the isolates as S. Paratyphi B dT+. The multiplex PCR test identified all 105 isolates as S. Paratyphi B dT+ strains. The concordance of the lead acetate test relative to that of multiplex PCR was 97.7% and 100% for protocol 1 and 2 respectively. This study showed that S. Paratyphi B dT+ is a common causative agent of gastroenteritis in Malaysia while paratyphoid fever appears to be relatively uncommon. Multiplex PCR was shown to be a simpler, more rapid and reliable method to discriminate S. Paratyphi B than the phenotypic lead acetate test.

Abstract. Salmonella enterica serovar Paratyphi B is known to cause either paratyphoid fever or gastroenteritis. Differentiation of Salmonella ser. Paratyphi B into biotype Java (d-tartrate fermenting, dT+) and biotype Paratyphi B (d-tartrate non-fermenting, dT) is important for Salmonella epidemiology. This study applied a PCR approach to differentiate the two biotypes to augment the conventional biochemical method and to determine the antibiograms and genomic diversity of Malaysian S. Paratyphi B. Among 100 strains tested (clinical, 86; non-humans, 14), only two clinical strains were confirmed as biotype Paratyphi B as indicated by both lead acetate test and PCR. Antibiotic resistance rates were as follows: streptomycin 18%, sulphonamides 13%, ampicillin 10%, chloramphenicol 4%, tetracycline 3%, cefotaxime 2%, cefpodoxime 2%, ceftazidime 2%, gentamicin 1% and trimethoprim 1%. None showed resistance towards amoxicillin-clavulanic acid, ceftiofur, ciprofloxacin, nalidixic acid and trimethoprim-sulphamethoxazole. Seven strains showed multidrug resistance towards 3 or more classes of antimicrobial agents. REP-PCR and PFGE generated 32 and 76 different profiles, respectively. PFGE (D = 0.99) was more discriminative than REP-PCR (D = 0.93) and antimicrobial susceptibility test (D = 0.48) in subtyping the strains. Strains isolated 18 years apart (1982 - 2008) from different localities in Malaysia were clonally related as demonstrated by REP-PCR and PFGE, indicating that these strains were stable and widely distributed. In some clusters, strains isolated from different sources (clinical, food and animal) were grouped together. Thus, biotype Java was the most common biotype of Salmonella ser. Paratyphi B in Malaysia. The PCR approach is highly recommended due to its simplicity, specificity and ease of operation. The level of antimicrobial resistance among Salmonella ser. Paratyphi B remained relatively low in Malaysia but the emergence of resistance to cephalosporins is a cause for concern.

The first Australian isolate of Salmonella enterica serovar Paratyphi B D-tartrate-utilizing (dT(+)) that is resistant to ampicillin, chloramphenicol, florfenicol, streptomycin, spectinomycin, sulfonamides, and tetracycline (ApCmFlSmSpSuTc) and contains SGI1 was isolated from a patient with gastroenteritis in early 1995. This is the earliest reported isolation globally. The incidence of infections caused by these SGI1-containing multiply antibiotic-resistant S. enterica serovar Paratyphi B dT(+) strains increased during the next few years and occurred sporadically in all states of Australia. Several molecular criteria were used to show that the early isolates are very closely related to one another and to strains isolated during the following few years and in 2000 and 2003 from home aquariums and their owners. Early isolates from travelers returning from Indonesia shared the same features. Thus, they appear to represent a true clone arising from a single cell that acquired SGI1. Some minor differences in the resistance profiles and molecular profiles also were observed, indicating the ongoing evolution of the clone, and phage type differences were common, indicating that this is not a useful epidemiological marker over time. Three isolates from 1995, 1998, and 1999 contained a complete sul1 gene but were susceptible to sulfamethoxazole due to a point mutation that creates a premature termination codon. This SGI1 type was designated SGI1-R. The loss of resistance genes also was examined. When strains were grown for many generations in the absence of antibiotic selection, the loss of SGI1 was not detected. However, variants SGI1-C (resistance profile SmSpSu) and SGI1-B (resistant to ApSu), which had lost part of the integron, arose spontaneously, presumably via homologous recombination between duplications in the In104 complex integron.

A total of 36 contemporary human, animal, and environmental (+)-tartrate-fermenting (dT+) Salmonella enterica serovar Paratyphi B isolates, formerly called Salmonella serovar Java, and five related monophasic S. enterica serovar 4,5,12:b:- isolates from Belgium, Germany, the Netherlands, and the United Kingdom were investigated for clonality and antimicrobial resistance profiles, as well as their virulence and resistance gene repertoire. Two major clonal lines, which could be phenotypically differentiated by the expression of the O:5 antigen, were identified. All O:5 antigen negative strains were multidrug resistant and originated (with two exceptions) from Belgian, Dutch, or German poultry. Strains exhibiting the O:5 antigen encoded by the oafA gene revealed a more heterogeneous group including multidrug-resistant and susceptible strains. Compared to O:5 antigen negative isolates, Salmonella Paratyphi B dT+ O:5 positive strains possessed additional virulence determinants. The Salmonella genomic island 1 was only found in O:5 positive strains. Five monophasic Salmonella 4,5,12:b:- lacking the phase-2 flagellar antigen were assigned to Salmonella Paratyphi B dT+ isolates of the O:5 positive group. The conclusion of the analysis is that Salmonella Paratyphi B dT+ O:5 negative and O:5 positive isolates evolved from a different lineage. Salmonella Paratyphi B dT+ O:5 positive strains possess additional fimbrial and virulence genes that probably enable this clone to interact with a broader range of hosts and the environment. Salmonella Paratyphi B dT+ O:5 negative continuously persists in poultry across Western Europe, especially Belgium, the Netherlands, and Germany.

Objective: Salmonella Paratyphi B dT+ (or Salmonella Java) is an emerging public health problem. The study objective was to characterize phenotypically and genotypically 13 human isolates from sporadic cases of infection., Material and Methods: Phenotypic characteristics of 13 human isolates were determined by phage typing, disk diffusion method for testing antimicrobial susceptibility to 11 antibiotics and screening for selected virulence markers, i.e bacterial adherence to xylene, motility and biofilm formation. Genotypic characteristics of the study isolates were determined by PCR with primers for the detection of class 1 integrons, plasmid profile analysis and PFGE for the study of genetic diversity., Results: The study isolates were classified into different phage types, with 3aI or 3aI variant being the most common (61.5%). All study isolates were resistant to streptomycin and sulfisoxazole, two of them were multiresistant (to streptomycin, sulfisoxazole, ampicillin and nalidixic acid). The study isolates showed low hydrophobicity, except for one isolate (2/08), and 5 isolates exhibited motility of > or = 50 mm. High biofilm formation was detected in 5 isolates. Class 1 integrons were not detected in any isolate and plasmid profile analysis revealed the presence of a 90-kb plasmid in 8 isolates. XbaI PFGE analysis differentiated the isolates into 6 pulsotypes (X1, X2, X2a, X3, X4,X5)., Conclusion: Although the study set of S. Paratyphi B dT+ (S. Java) was small, the increasing emergence of this serovar in the human population in Slovakia is noteworthy. The results of gene analysis in PFGE suggest clonal diversity as well as a clonal link between strains of the predominant phage type. In view of possible increase in antimicrobial resistance and the spread of certain clones, continuous surveillance of strains of S. Paratyphi B dT+ is needed.

PCR methodology was developed to identify Salmonella enterica serovars Typhi, Paratyphi A, and Paratyphi B. One multiplex PCR identifies serogroup D, A, and B and Vi-positive strains; another confirms flagellar antigen "d," "a," or "b." Blinded testing of 664 Malian and Chilean Salmonella blood isolates demonstrated 100% sensitivity and specificity.

Salmonella enterica subspecies enterica serovar Paratyphi B [O1,4,(5),12 : Hb : 1,2] can cause either an enteric fever (paratyphoid fever) or self-limiting gastroenteritis in humans. The d-tartrate non-fermenting variant S. enterica subsp. enterica serovar Paratyphi B dT- (S. Paratyphi B) is the causative agent of paratyphoid fever, and the d-tartrate fermenting variant S. enterica subsp. enterica serovar Paratyphi B dT+ (S. Paratyphi B dT+; formerly called Salmonella Java) causes gastroenteritis. S. Java is currently recognized as an emerging problem worldwide. Twelve dT+ S. Java isolates were collected in Indonesia between 2000 and 2002. One-third of them contained Salmonella genomic island 1 (SGI1), which gives the multidrug-resistant phenotype to the bacteria. In this study, a PCR-based method to detect a single nucleotide difference responsible for the inability to ferment d-tartrate, reported elsewhere, was validated. The d-tartrate fermenting phenotype of S. Java was converted to the non-fermenting phenotype by the disruption of the ORF STM 3356, and the d-tartrate non-fermenting phenotype of the ORF STM 3356-disrupted strain and the dT- reference strain was changed to the dT+ phenotype by complementing ORF STM 3356 in trans. The results show that the dT+ phenotype requires a functional product encoded by STM 3356, and support the use of the PCR-based discrimination method for S. Paratyphi B and S. Java as the standard differentiation method.

Salmonella serotype Paratyphi B isolates obtained from shellfish and human infections in Galicia (northwest Spain) from 1998 were investigated by different phenotypic and genetic methods to evaluate their systemic or enteric nature. Isolates were investigated for D-tartrate fermentation, presence of genes encoding the effector proteins sopE1 and avrA, pulsed-field gel electrophoresis profile, and antimicrobial susceptibility. Systemic variant strains (dT-) were the dominant among the marine environment isolates. All dT- isolates were sopE1 positive and avrA negative, presented an indistinguishable electrophoresis profile, and were grouped in a single cluster. More electrophoresis heterogeneity was observed among dT+ isolates. Only two isolates showed resistance to any of the 16 antibiotics included in our panel. The present study identified the marine environment as a potential natural source of systemic variant isolates of Salmonella Paratyphi B. The presence of systemic variant isolates of Salmonella Paratyphi B in the marine environment is of notable public health significance as a result of the potential risk of acquiring enteric fever linked to the consumption of raw shellfish.

Our report highlights a case of severe childhood salmonellosis related to a pet turtle, a red-eared slider (Trachemys scripta elegans). A 6-year-old girl had gastroenteritis complicated with sepsis caused by serotype Paratyphi B, which shared the same pulsed-field gel electrophoresis profiles with the organism isolated from a pet turtle. Based on our literature survey on childhood invasive salmonellosis acquired from reptiles, this case is the first documented reptile-associated salmonellosis including sepsis caused by this serotype.

This study was conducted to investigate the occurrence of multiple-antibiotic resistance among 261 clinical isolates of Salmonella enterica serotype Paratyphi B strains collected between 2000 and 2003 through the network of the French National Reference Center for Salmonella. The 47 multidrug-resistant (MDR) isolates identified (18%), were characterized on the basis of the presence of several resistance genes (bla(TEM), bla(PSE-1), bla(CTX-M), floR, aadA2, qacEdelta1, and sul1), the presence of Salmonella genomic island 1 (SGI1) by PCR mapping and hybridization, and the clonality of these isolates by several molecular (ribotyping, IS200 profiling, and pulsed-field gel electrophoresis [PFGE]) and phage typing methods. The results of PCR and Southern blot experiments indicated that 39 (83%) of the 47 S. enterica serotype Paratyphi B biotype Java MDR isolates possessed the SGI1 cluster (MDR/SGI1). Among these 39 MDR/SGI1 isolates, only 3 contained variations in SGI1, SGI1-B (n = 1) and SGI1-C (n = 2). The 39 MDR/SGI1 isolates showed the same specific PstI-IS200 profile 1, which contained seven copies from 2.6 to 18 kb. Two PstI ribotypes were found in MDR/SGI1 isolates, RP1 (n = 38) and RP6 (n = 1). Ribotype RP1 was also found in two susceptible strains. Analysis by PFGE using XbaI revealed that all the MDR/SGI1 isolates were grouped in two related clusters, with a similarity percentage of 82%. Isolation of MDR/SGI1 isolates in France was observed mainly between the second quarter of 2001 and the end of 2002. The source of the contamination has not been identified to date. A single isolate possessing the extended-spectrum beta-lactamase bla(CTX-M-15) gene was also identified during the study.

An epidemiological investigation of a calf rearing premises and a closely associated dairy herd was carried out after the isolation of Salmonella enterica serovar Paratyphi B variant Java phage type 3b variant 2 from clinically diseased calves on the premises. The isolate was resistant to ampicillin, chloramphenicol, streptomycin, sulphonamides, tetracyclines, trimethoprim and cefoperazone. The organism was widespread on the calf unit and was also recovered from the dairy premises, mainly from groups of weaned calves. The investigation was extended to 10 epidemiologically linked farms but no S Java was isolated from any of the 40 to 60 samples collected from each premises. Molecular studies showed that the S Java isolates were genetically most similar to isolates from cases of human disease associated with ornamental fish tanks or feed. Long PCR and resistance gene profiling identified a resistance island which was indistinguishable from the human 'fish tank' strain of S Java and animal and human epidemic strains of S Typhimurium DT104. The isolates were clearly distinguished from multi-resistant S Java strains commonly associated with continental poultry. This is the first report of S Java with this resistance pattern in Great Britain.

We document an increase in the number of multidrug-resistant Salmonella enterica serovar Paratyphi B dT+ identified in Canada. Most of these strains harbor Salmonella genomic island 1 (SGI1). Further studies are needed to determine factors contributing to the observed emergence of this multidrug-resistant strain.

The presence of integrons in 85 multiresistant German isolates of the predominating Salmonella enterica subsp. enterica serovar Paratyphi B dT(+) clone was investigated. All isolates possessed a chromosomally located Tn7-like class 2 integron carrying the same dfrA1-sat1-aadA1 array of gene cassettes. Only four isolates (4.7%) revealed an additional class 1 integron with two strains each containing the aadA1 or dfrA1-aadA1 gene cassettes.

Salmonella enterica serotype O1,4,5,12:Hb:1,2, designated according to the current Kauffmann-White scheme as S. enterica serotype Paratyphi B, is a very diverse serotype with respect to its clinical and microbiological properties. PCR and blot techniques, which identify the presence, polymorphism, and expression of various effector protein genes, help to distinguish between strains with systemic and enteric outcomes of disease. All serotype Paratyphi B strains from systemic infections have been found to be somewhat genetically related with respect to the pattern of their virulence genes sopB, sopD, sopE1, avrA, and sptP as well as other molecular properties (multilocus enzyme electrophoresis type, pulsed-field gel electrophoresis [PFGE] type, ribotype, and IS200 type). They have been classified as members of the systemic pathovar (SPV). All these SPV strains possess a new sopE1-carrying bacteriophage (designated PhiSopE309) with high SopE1 protein expression but lack the commonly occurring avrA determinant. They exhibit normal SopB protein expression but lack SopD protein production. In contrast, strains from enteric infections classified as belonging to the enteric pathovar possess various combinations of the respective virulence genes, PFGE pattern, and ribotypes. We propose that the PCR technique for testing for the presence of the virulence genes sopE1 and avrA be used as a diagnostic tool for identifying both pathovars of S. enterica serotype Paratyphi B. This will be of great public health importance, since strains of serotype Paratyphi B have recently reemerged worldwide.

Aims: DNA fingerprinting of Salmonella enterica serotype Paratyphi B isolated in Malaysia during 1982-83, 1992 and 1996-2002 was carried out by pulsed-field gel electrophoresis (PFGE), antimicrobial susceptibility tests and D-tartrate utilization tests to assess the extent of genetic diversity of these isolates in Malaysia., Methods and Results: Eighty-six human isolates and one food isolate of Salm. Paratyphi B were analysed by PFGE, antimicrobial susceptibility tests and D-tartrate utilization tests. Sixty-five strains were D-tartrate-negative (dT-) while 22 strains were D-tartrate-positive (dT+). Thirty-seven per cent of the Salm. Paratyphi B strains were resistant to one or more antimicrobial agents. PFGE analysis clearly distinguished the dT- and dT+ strains into two clusters based on the unweighted pair group average method (UPGMA). Twenty-two XbaI-pulsotypes were observed among the 65 dT- strains while 17 XbaI-pulsotypes were observed among the 22 isolates of Salm. Paratyphi B dT+., Conclusions: The present study showed that PFGE was very discriminative with 33.7% of the strains yielding distinct fingerprints. Paratyphoid fever in Malaysia is probably caused by one predominant, endemic clone of Salm. Paratyphi B dT- with various subtypes. There was no association between the pulsotypes and the severity of the disease indicating that the severity of the disease is probably multifactorial., Significance and Impact of the Study: The findings of the present study verify the usefulness of PFGE in characterizing strains of Salm. Paratyphi B. This is the first report on the application of PFGE on a large collection of Salm. Paratyphi B in Malaysia.

During the summer of 1999, several Norwegian tourists returning from Turkey became ill as a result of Salmonella enterica serovar paratyphi B (S. paratyphi B) infection. We examined the S. paratyphi B isolates from 14 of these patients (10 from blood cultures, 4 from stool specimens) who were admitted to 2 hospitals in Bergen, Norway during August and September 1999. Moreover, during the same period, a laboratory technician working at 1 of these hospitals was admitted with S. paratyphi B septicemia and was included in the study. Using repetitive-sequence-based PCR (rep-PCR) with 2 primer pairs (ERIC and REP), pulsed-field gel electrophoresis and phage typing we found that the laboratory technician was infected with the same S. paratyphi B clone as the 14 tourists. The discriminatory capacity of the rep-PCR method and pulsed-field gel electrophoresis was examined using S. paratyphi B strains from the outbreak and from other geographical locations. We conclude that a combination of rep-PCR with the ERIC primer pair and phage typing was useful in discriminating between the epidemic isolates and epidemiologically unrelated isolates from S. paratyphi B infections and that the laboratory technician was most likely infected while handling patient samples or bacterial cultures from the Turkish tourists.

The results of the rapid method for the detection and identification of epidemically related and unrelated causative agents of Salmonella infections. To analyze the chromosomal DNA of these strains, rapid polymerase chain reaction (PCR) was used. The analysis of the electrophoregrams of products obtained in rapid PCR revealed that the number of DNA fragments is constant for the cultures of the concrete serovar or phagovar. Using rapid PCR, the detection of S. typhi atypical strains was succeeded.

The genomic cleavage map of Salmonella paratyphi B was determined through digestion with endonucleases and separation of the fragments by pulsed-field gel electrophoresis. The chromosome has 19 XbaI sites, 10 BlnI sites, and 7 CeuI sites. The fragments were arranged in order through excision of fragments from the gel, redigestion with a second enzyme, end labelling with 32P, and reelectrophoresis. Tn10 transposons inserted in 61 different genes of S. typhimurium LT2 were transduced by use of bacteriophage P22 into S. paratyphi B. The locations of Tn10 insertions on the chromosome of S. paratyphi B were determined by use of XbaI and BlnI sites in Tn10, revealing the positions of genes with Tn10 insertions in S. paratyphi B. All seven CeuI sites (in rrl genes for 23S rRNA) and most of the XbaI and BlnI sites in rrn genes for Glt-tRNA are conserved, but only about half of the XbaI and BlnI sites outside rrn genes are conserved. Gene order is identical in the 68 genes that we could compare between S. paratyphi B and S. typhimurium LT2, and the lengths of intervals between the genes are often the same, but there are several instances of differences in interval lengths, indicating that insertions or deletions of DNA have occurred during the evolutionary divergence of these bacteria.

A total of 4801 Salmonella strains of 67 serovars isolated from various sources in 1968-1982 were studied for their sensitivity to 12 drugs. The Salmonella strains of groups A, B, C, D and E amounted to 0.8, 84.6, 6.4, 5.8 and 2.0 per cent, respectively. The Salmonella strains of the other groups amounted to 0.4 per cent. During the 5-year periods, the number of the antibiotic resistant Salmonella strains increased from 57.7 to 93.4 per cent. The conjugative drug resistance was detected in 16 out of the 67 serovars. The Salmonella strains usually resistant to 4-10 drugs were the donors of this conjugative drug resistance. The strains of S. typhimurium responsible for the hospital infections were characterized by the highest levels of the antibiotic polyresistance and the greatest variety of the conjugative R plasmids. The structure of the multiple and conjugative drug resistance of the organisms causing salmonellosis was more frequently defined by the conjugative plasmids of the antibiotic resistance of the S. typhimurium serovar. The Salmonella R plasmids determined various levels of the antibiotic resistance. The highest resistance levels were observed to benzylpenicillin, chloramphenicol and erythromycin and the lowest resistance levels to tetracycline.

The plasmids characterized in Algeria generally belong to the C and F1 me compatibility groups. With the exception of Vibrio cholerae el for the two groups are found in many bacterial species. Plasmids belonging to group C are the only stable in Vibrio cholerae el tor. The possibility that epidemics of Vibrio cholerae el tor carrying C plasmids might be observed, should not be excluded. On the other hand, it is presently impossible to guess what will be the future epidemic plasmid in Salmonella typhi and paratyphi B.

The distribution of R plasmids in six drug-resistant Salmonella typhi strains and four S. paratyphi B strains isolated from human in Algeria was studied. All strains but one S. typhi harbored one conjugative R plasmid. Plasmids belonging to the incompatibility groups FIme, B, W or P were found in the S. typhi strains and those belonging to groups FIme or B were found in the S. paratyphi B strains. The epidemiological surveillance of R plasmids shows that the drug resistance of these strains is not the result of the epidemic spread of particular strains of Salmonella.

Among 262 strains of Salmonella typhi from an epidemic outbreak of typhoid fever in Baden-Württemberg in 1974 2 strains were isolated which were tetracyclin resistant and showed no reactions with the Vi testphages T, D6 and VII whilst all other strains belonged to lysotype A, subtype Tananarive. It turned out that the Tc resistance in both strains was caused by a fi- R plasmid which could be transfered to other S. typhi strains, to E. coli K12, S. paratyphi B, S. java and S. typhi-murium as well as from Tc resistant E. coli K12 back to S. typhi. The Tc R plasmid introduced in S. typhi, lysotype A, caused specific restrictions of typing phages T, D6 and VII. Also, the transfer of the plasmids to strains of S. paratyphi B and S. typhi-murium resulted in restrictions of a number of typing phages. Both plasmids had identical patterns of restriction. In this pattern the Tc R plasmid differed from those described in the literature.

The plasmid determinant of resistance to fosfomycin (For) was cloned into pBR322 and located in a 0.7-kilobase segment of DNA by transposon mutagenesis and in vitro deletion analysis. It encodes an 18-kilodalton protein located in the cytoplasm of resistant cells. Its synthesis is constitutive. The For genetic determinant is common to all plasmids isolated since 1975 in an hospital environment as determined by DNA-DNA hybridization. However, plasmids which carry For can be divided into two groups on the basis of size, pattern of antibiotic resistances, incompatibility specificity, and restriction and hybridization properties.

The pathogenicity level of antibiotic sensitive and streptomycin resistant strains of S. typhimurium, S. paratyphi B and S. kottbus changed under the effect of identical R plasmids more frequently in contrary directions. The conjugative plasmids of antibiotic resistance widened the ranges of the virulence changes in the Salmonella serovars for albino mice. It was found that 7 out of 8 plasmids studied significantly decreased and increased the virulence of the antibiotic sensitive Salmonella strains. As a rule, R plasmids of various origin decreased the virulence of all the tested streptomycin chromosome resistant causative agents of salmonellosis.