IS200 fingerprinting of Salmonella enterica serotype Abortusovis strains isolated in Iran

Salmonella enterica serovar Abortusovis is one of the most common pathogens responsible for abortion in sheep. In Iran, the spread of Abortusovis is highly dependent on the nomadic life style. In this study we performed IS200 fingerprinting to identify the clonal lines circulating in Iran. All the isolates contained 4 or 5 copies of the transposon and could be classified in 4 genotypes. A single genotype was highly prevalent and very likely it has circulated in Iran since 1970. All the isolates showed a high degree of relatedness.     

Grouping of Salmonella enterica serotype Montevideo strains by ribotyping and IS200 profiling

One-hundred and twenty-one isolates of Salmonella enterica serotype Montevideo, representing different biotypes and incidents of infection detected in the UK between 1977 and 1995, were analysed by EcoRI ribotyping, PvuII ribotyping and IS200 fingerprinting. Among the isolates examined, 7 EcoRI ribotypes, 5 PvuII ribotypes and 55 IS200 profile types were recognized and 4 arbitrary groups defined. All 33 isolates of biotype 2d belonged to EcoRI/PvuII ribotype 1/1 and IS200 lineage A and comprised Group I. The other 88 isolates of biotype 10di and its variants were assigned to Groups II-IV. All 27 isolates in Group II were of EcoRI/PvuII ribotype 2/2 and IS200 lineage B. Among the 43 isolates in Group III, 42 of which were of EcoRI/PvuII ribotype 3/3, IS200 analysis identified 38 profiles in lineages C-I. Six EcoRI/PvuII ribotypes and 8 IS200 profiles, mostly in lineages C-E, were recognized among the 18 isolates in Group IV. The combined use of biotyping and ribotyping, and to some extent IS200 profiling, has enhanced our understanding of the clonal structure of serotype Montevideo and provides a basis for further study.     

Ciprofloxacin-resistant Salmonella enterica serotype Typhimurium, China

We characterized 44 Salmonella enterica serotype Typhimurium isolates from Tongji Hospital outpatients in Wuhan, China, May 2002-October 2005. All 31 ciprofloxacin-resistant isolates were also resistant to > or = 8 other antimicrobial drugs and carried > or = 2 mutations in GyrA and 1 mutation in ParC. Class 1 integrons were identified in 37 isolates.     

Characteristics of strains of Salmonella enterica serovar Typhimurium DT104 isolated in the Slovak Republic

From 1997 to 2000 in the Slovak Republic 8 strains of Salmonella enterica serovar Typhimurium DT104 were isolated from sporadic cases of human salmonellosis. Four strains were multiresistant and three strains were sensitive to antibiotics. We investigated the influence of the cultivation medium (complete Müeller-Hinton, synthetic-Staples) on growth, surface hydrophobicity and motility of the mentioned isolates. The hydrophobicity was evaluated by methods of adherence to the hydrocarbon xylene (BATH) in a salt-aggregation test with ammonium sulphate (SAT) and adherence to a plast. The growth of tested strains in 24 hours was greater after cultivation in the complete medium, but the salmonellae grew considerably also in the synthetic medium where the only source of C and N was asparagine. Of the investigated characteristics the cultivation medium influenced most the adherence of isolates to xylene as after cultivation in a synthetic medium all isolates with the exception of two were hydrophobic. The motility of strains was also greater after growth in this medium. Conversely cultivation in complete medium suppressed these properties of isolates. The cultivation medium did not influence the adherence of isolates to plasts and only a slight influence was observed on the salt aggregating properties of the investigated strains.     

Genotypic diversity and antimicrobial resistance in asymptomatic Salmonella enterica serotype Typhimurium DT104.

The recent emergence of multidrug-resistant Salmonella enterica subspecies enterica serotype Typhimurium phage-type DT104 represents a challenge to health workers from both human and veterinary medicine. In an effort to develop effective control strategies, it is vital to characterize accurately the extent of genetic and phenotypic variation present in the pathogen population. While previous studies have focused on disease-associated populations, we report the genetic diversity and the diversity in antimicrobial resistance associated with asymptomatic Salmonella Typhimurium DT104 isolates found in pigs. Using pulsed-field gel electrophoresis (XbaI and SpeI), we identified 62 different genotypes associated to 13 different antimicrobial resistant phenotypes among 80 asymptomatic DT104 isolates collected from the Canadian swine industry. When rarefaction curves of a subsample the asymptomatic isolates were compared to that of disease-associated isolates from a similar spatial and temporal scale, we identified significantly more genotypes among the asymptomatic populations with 27 PFGE patterns against 23.0+/-1.4 (95% confidence intervals) in the latter. Also, using Simpson's diversity index, we observed considerably higher genetic and phenotypic diversity in the asymptomatic isolates within herds and detected possible patterns of periodic selection within the disease-associated population. We thus concluded that an important aspect of Salmonella population structure and ecology is overlooked in investigations of disease-associated isolates.     

Salmonella enterica serotype Typhimurium DT 104 antibiotic resistance genomic island I in serotype paratyphi B

We have identified Salmonella genomic island I (SGI1) in an isolate of Salmonella enterica serotype Paratyphi B. This antibiotic-resistance gene cluster, which confers multidrug resistance, has been previously identified in S. enterica serotype Typhimurium phage types DT 104 and DT 120 and in S. enterica serotype Agona.     

A community-based outbreak of Salmonella enterica serotype Typhimurium associated with salami consumption in Northern Italy.

An outbreak of Salmonella enterica serotype Typhimurium belonging to phage type (PT) 193 occurred in autumn 1995 and involved 83 individuals in a large area of Northern Italy (Lombardy Region). Epidemiological and microbiological investigations of strains isolated from clinical and food specimens revealed that the vehicle was a batch of salami, produced on 4 September 1995 by a local firm. The outbreak was contained when the batch was withdrawn from sale. Insufficient ripening of the salami had allowed the salmonella to survive, emphasizing the need to define criteria for the ripening process of foods such as salami.     

The evolution and distribution of phage ST160 within Salmonella enterica serotype Typhimurium

Salmonellosis is an internationally important disease of mammals and birds. Unique epidemics in New Zealand in the recent past include two Salmonella serovars: Salmonella enterica subsp. enterica serovar Typhimurium definitive type (DT) 160 (S. Typhimurium DT160) and S. Brandenburg. Although not a major threat internationally, in New Zealand S. Typhimurium DT160 has been the most common serovar isolated from humans, and continues to cause significant losses in wildlife. We have identified DNA differences between the first New Zealand isolate of S. Typhimurium DT160 and the genome-sequenced strain, S. Typhimurium LT2. All the differences could be accounted for in one cryptic phage ST64B, and one novel P22-like phage, ST160. The majority of the ST160 genome is almost identical to phage SE1 but has two regions not found in SE1 which are identical to the P22-like phage ST64T, suggesting that ST160 evolved from SE1 via two recombination events with ST64T. All of the New Zealand isolates of DT160 were identical indicating the clonal spread of this particular Salmonella. Some overseas isolates of S. Typhimurium DT160 differed from the New Zealand strain and contained SE1 phage rather than ST160. ST160 was also identified in New Zealand isolates of S. Typhimurium DT74 and S. Typhimurium RDNC-April06 and in S. Typhimurium DT160 isolates from the USA. The emergence of S. Typhimurium DT160 as a significant pathogen in New Zealand is postulated to have occurred due to the sensitivity of the Salmonella strains to the ST160 phage when S. Typhimurium DT160 first arrived.     

An outbreak of multidrug-resistant Salmonella enterica subsp. enterica serotype Typhimurium, DT104L linked to dried anchovy in Singapore

Multidrug-resistant Salmonella enterica subsp. enterica serotype Typhimurium DT104L was first reported in Singapore from mid-July to mid-October 2000. Salmonella strains isolated from clinical laboratories were submitted to a reference laboratory for serotyping, phage-typing and pulsed-field gel electrophoresis (PFGE) using XbaI restriction endonuclease. An epidemiological investigation was conducted to determine the source of infection and mode of transmission using a structured questionnaire. A total of 33 cases involving mainly infants and toddlers were detected in the 3-month long outbreak. The outbreak strain was of the R-type ACGSTSu, i.e. resistant to ampicillin, chloramphenicol, gentamicin, streptomycin, tetracycline and sulphonamide. PFGE showed all isolates had an indistinguishable pattern, indicating a common source of infection. Consumption of imported dried anchovy was found to be the vehicle of transmission after adjusting for all confounding variables in the case-control study using stepwise logistic regression (OR 25.6; 95% CI 3.9-167.9; P = 0.001). Imported dried seafood should be properly processed, packed, labelled, and thoroughly cooked to prevent transmission of multidrug-resistant S. Typhimurium.     

Salmonella enterica serotype Typhimurium DT104 isolated from humans, United States, 1985, 1990, and 1995

First isolated from an ill person in 1985, multidrug-resistant Salmonella enterica serotype Typhimurium DT104 emerged in the mid-1990s as a strain of Salmonella frequently isolated from humans in the United States. We compared the integron content, plasmid profile, and XbaI pulsed-field gel electrophoresis (PFGE) patterns of multidrug-resistant S. Typhimurium DT104 (MR-DT104) isolated from humans in the United States in 1985, 1990, and 1995. All isolates contained a 60-mDa plasmid and had indistinguishable PFGE and integron profiles, supporting the idea of a clonal relationship between recent and historical isolates. The data suggest that the widespread emergence of MR-DT104 in humans and animals in the 1990s may have been due to the dissemination of a strain already present in the United States rather than the introduction of a new strain.     

Molecular typing of Salmonella serotype Thompson strains isolated from human and animal sources

One-hundred-and-thirteen isolates of Salmonella serotype Thompson from diverse sources in seven countries were characterized by PvuII ribotyping and IS200 fingerprinting. Ten PvuII ribotypes were observed. The predominant PvuII ribotype 1 represented a major clone of world-wide distribution but was not found in Australia; PvuII ribotypes 2 and 3 represented minor clones. HincII ribotyping discriminated subtypes within PvuII ribotype 1: HincII ribotype 1 was distributed widely but HincII ribotype 2 was found mainly in Scottish isolates. None of 101 isolates of PvuII ribotypes 1-3 contained copies of IS200. All 12 isolates of PvuII ribotypes 4-10 were from Australia and 7 of them contained copies of IS200 of 5 different profiles. These results suggest the existence of at least two lineages of Salmonella Thompson with a different geographical distribution. The finding that most isolates from man and poultry in Scotland belonged to the same ribotype (PvuII 1/HincII 2) and were IS200-negative suggests that poultry is an important source of human infection in Scotland.     

Multidrug-resistant strains of Salmonella enterica Typhimurium, United States, 1997-1998

To evaluate multidrug-resistant strains of Salmonella enterica serotype Typhimurium, including definitive type 104 (DT104) in the United States, we reviewed data from the National Antimicrobial Resistance Monitoring System (NARMS). In 1997 to 1998, 703 (25%) of 2,767 serotyped Salmonella isolates received at NARMS were S. Typhimurium; antimicrobial susceptibility testing and phage typing were completed for 697. Fifty-eight percent (402) were resistant to > or = 1 antimicrobial agent. Three multidrug-resistant (> or = 5 drugs) strains accounted for (74%) 296 of all resistant isolates. Ceftriaxone resistance was present in 8 (3%), and nalidixic acid resistance in 4 (1%), of these multidrug-resistant strains. By phage typing, 259 (37%) of S. Typhimurium isolates were DT104, 209 (30%) were of undefined type and 103 (15%) were untypable. Fifty percent (202) of resistant (> or = 1 drug) isolates were DT104. Multidrug-resistant S. Typhimurium isolates, particularly DT104, account for a substantial proportion of S. Typhimurium isolates; ceftriaxone resistance is exhibited by some of these strains.     

Intranasal immunogenicity of a Deltacya Deltacrp-pabA mutant of Salmonella enterica serotype Typhimurium for the horse

The aim of this study was to investigate the intranasal immunogenicity for the horse of a Deltacya Deltacrp-pabA mutant (MGN-707) of Salmonella enterica serotype Typhimurium (S. typhimurium). MGN-707 caused no sign of disease, was not detected in feces and a single administration induced strong Salmonella-specific serum and nasal mucosal antibody responses. All ponies had made strong salmonella specific serum IgGa, IgGb, IgA and IgM antibody responses by day 25 after the first immunization. IgM responses to salmonella lipopolysaccharide (LPS) were short lived whereas salmonella specific serum IgGa and IgGb persisted at high levels in all ponies until 83 and 140 days, respectively. Specific nasal mucosal antibody responses dominated by IgA and IgM were evident by day 25 in all ponies except one in which only specific IgGa and IgGb were evident. Specific nasal mucosal IgA persisted in most ponies until day 69. A second immunization on day 140 boosted antibody responses, and stimulated a strong nasal mucosal IgA response in the pony that failed to make an IgA response after primary immunization. At the termination of the experiment, IgA and IgGb dominated jejunal antibody responses whereas vaginal responses were mainly IgA. The latter response unequivocally confirms the existence of a common mucosal immune system in equids. The results indicate that a S. typhimurium Deltacya Deltacrp-pabA mutant has potential as an intranasal vaccine against salmonellosis in the horse.     

Mycobacterium avium Subsp. avium and Salmonella enterica serotype Typhimurium var. Copenhagen phage type DT2 in pigeons

We report on a coinfection of Mycobacterium avium subsp. avium and Salmonella enterica serotype Typhimurium var. Copenhagen phage type DT2 in pigeons from one flock, from which squabs were occasionally consumed by humans. Triplex quantitative real-time PCR and culture methods were used for M. a. avium detection in livers and culture method was used for the detection of Salmonella sp. in samples of liver and caecum of 33 examined birds. M. a. avium was detected in a total of 31 (93.9%) and Salmonella Typhimurium in a total of 11 (33.3%) pigeons. Coinfection with both pathogens was found in 10 (30.3%), infection with Salmonella Typhimurium alone in 1 (3.0%), and infection with M. a. avium alone in 21 (63.7%) pigeons. Neither pathogen was detected in one pigeon. There was no difference in clinical symptoms exhibited by pigeons infected by M. a. avium and/or Salmonella Typhimurium. All Salmonella Typhimurium isolates were sensitive to all 15 antimicrobials tested. According to these results we emphasize good heat treatment of consumed squabs.     

Emergence of multidrug-resistant Salmonella enterica serotype Typhimurium phage-type DT104 among salmonellae causing enteritis in Israel

The relative frequency of salmonella strains isolated from hospitalized and non-hospitalized patients in Southern Israel changed during the period, 1994-6. Salmonella enterica serotype Typhimurium definitive phage-type 104 (DT104) appeared in Israel in 1994 and became the most prevalent strain in 1996. An outbreak of enteritis due to Salmonella enterica serotype Agona occurred in Israel, in October 1994 and lasted for 4 months. The relative frequency of Salmonella enterica serotype Enteritidis remained almost constant during these years, with seasonal fluctuations only. The importance of the increase in the prevalence of Typhimurium DT104 has been the epidemic spread of a multiresistant strain of R-type ACT (A, ampicillin; C, chloramphenicol; T, tetracycline) belonging to this phage-type. Since 1995 the frequency of Typhimurium DT104 isolates that possess, in addition to the above R-type, a chromosomally encoded resistance to the quinolone drug, nalidixic acid, increased tenfold. In 1996, 27% of the Typhimurium DT104 isolates were of R-type ACTN. S. Enteritidis exhibited over 95% susceptibility to at least eight of the most commonly used antibiotic drugs, and none of the isolates was resistant to quinolone or fluoroquinoline.     

Virulotyping of Salmonella enterica serovar Napoli strains isolated in Italy from human and nonhuman sources

Salmonella enterica serovar Napoli is an emerging serovar in Italy, France, and Switzerland, but little is known about its pathogenicity to humans. A collection of 112 strains of Salmonella Napoli isolated in Italy from human cases, foods of animal origin, and the environment have been characterized by the detection of a set of virulence genes, pulsed-field gel electrophoresis (PFGE), and antibiotic susceptibility. All the strains examined were susceptible to all the antimicrobials tested. The Salmonella pathogenicity islands genes ssaQ, mgtC spi_4D, and sopB were present from 75.0% to 100% of the tested strains. Only one human and four environmental strains showed the avrA gene. The phage-related sopE1 gene was present in 93% of the strains, whereas sodC1 and gipA genes were only in four and two environmental strains, respectively. The bcfC fimbrial gene was present in all the animal/food strains, in the 71.4% of environmental strains, and in 46.8% of the human strains, respectively. Overall, we observed 10 distinct virulence profiles (VP), but VP1-2-3 included 99 out of 112 strains. PFGE showed that 103 out of 111 isolates were grouped in four major clusters and three minor clusters, whereas two strains were totally unrelated. The most represented PFGE clusters mainly correlated with the virulotypes are VP1, VP2, and VP3. Salmonella Napoli shows an array of virulence genes similar to other serovars considered of public health importance and confirming its capability to cause infection in human. Concerning possible source of infection or reservoirs, the results did not point out any, but our hypothesis is that the environment can act as the main reservoir for Salmonella Napoli, and from there it can spill over to animals and humans. Further studies are needed to increase the knowledge on the ecology of Salmonella Napoli serovar and on the main risk factors for human infection.     

Molecular fingerprinting of multidrug-resistant Salmonella enterica serotype Typhi.

For epidemiologic investigations, the primary subdivision of Salmonella Typhi is vi-phage typing; 106 Vi-phage types are defined. For multidrug-resistant strains the most common types have been M1 (Pakistan) and E1 (India, Pakistan, Bangladesh, and the Arabian Gulf); a strain untypable with the Vi phages has been responsible for a major epidemic in Tajikistan. Most often, isolates from the Indian subcontinent have been resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, tetracyclines, and trimethoprim; but in the 1997 Tajikistan outbreak, the epidemic strain was also resistant to ciprofloxacin. For multidrug-resistant strains, subdivision within phage type can be achieved by plasmid profile typing and pulsed-field gel electrophoresis.     

Molecular characterization of Salmonella enterica subsp. enterica serovar Typhimurium DT1 isolates

Salmonella Typhimurium DT1 is endemic to Finland and has caused human outbreaks since the 1960s. Domestic DT1 isolates (n=235) from 1972 to 1999 from human cases, animals and other sources, as well as foreign DT1 isolates from human cases (n=20) were analysed by molecular methods. Pulsed-field gel electrophoresis (PFGE) yielded 38 XbaI profiles. Of these, XbaI profile 10 was seen in 49% (125/255) of the isolates. Twelve IS200 profiles were obtained; the most common IS200 profile D was seen in 64% (33/52) of the isolates. Two clusters were formed by compilation of the XhaI-, BlnI- and SpeI-PFGE and IS200 profiles and possession of the serovar-specific virulence plasmid. The major cluster contained eight IS200 profiles, including IS200 profile D and XhaI profile 10, and had no virulence plasmid, and can be regarded as typical of the endemic Typhimurium DT1 infection.     

Drug-resistant Salmonella enterica serotype paratyphi A in India

The incidence of enteric fever caused by Salmonella enterica serotype Paratyphi A has been increasing in India since 1996. In 1998, the incidence of enteric fever caused by drug- resistant S. Paratyphi A abruptly increased in the New Delhi region. In the first 6 months of 1999, 32% of isolates were resistant to both chloramphenicol and cotrimoxazole and another 13% were resistant to more than two antibiotics.     

Intranasal immunogenicity of a Delta cya Delta crp-pabA mutant of Salmonella enterica serotype Typhimurium for the horse

The aim of this study was to investigate the intranasal immunogenicity for the horse of a Deltacya Deltacrp-pabA mutant (MGN-707) of Salmonella enterica serotype Typhimurium (S. typhimurium). MGN-707 caused no sign of disease, was not detected in feces and a single administration induced strong Salmonella-specific serum and nasal mucosal antibody responses. All ponies had made strong salmonella specific serum IgGa, IgGb, IgA and IgM antibody responses by day 25 after the first immunization. IgM responses to salmonella lipopolysaccharide (LPS) were short lived whereas salmonella specific serum IgGa and IgGb persisted at high levels in all ponies until 83 and 140 days, respectively. Specific nasal mucosal antibody responses dominated by IgA and IgM were evident by day 25 in all ponies except one in which only specific IgGa and IgGb were evident. Specific nasal mucosal IgA persisted in most ponies until day 69. A second immunization on day 140 boosted antibody responses, and stimulated a strong nasal mucosal IgA response in the pony that failed to make an IgA response after primary immunization. At the termination of the experiment, IgA and IgGb dominated jejunal antibody responses whereas vaginal responses were mainly IgA. The latter response unequivocally confirms the existence of a common mucosal immune system in equids. The results indicate that a S. typhimurium Deltacya Deltacrp-pabA mutant has potential as an intranasal vaccine against salmonellosis in the horse.