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1.
By PCR using the ant(3")-Ia primer pair the aadA gene was detected in 34 streptomycin- and spectinomycin-resistant Salmonella enterica serotype Typhimurium strains. Out of them 12 belonged to DT104 and 22 to non-DT104 phage type. Using different primer combinations it was demonstrated that this gene was integron-associated in all cases: in the DT104 strains it was generally contained by a 1 kb integron while in the majority of the non-DT104 strains by a 2.05 kb (less often by a 1.9 or 1 kb) integron. In the case of integrons carrying multiple cassettes the cassette containing the aadA gene was located closer to the 3' end of the integron. The aadA genes of DT104 and non-DT104 strains were different: in the former group the aadA2 gene, while in the latter group (constituted by strains of five different phages types as well as unclassifiable and untypable strains) the aadA1 gene could be identified. The RH50/RH51 primer pair described by Collis and Hall (1992) proved to be suitable for rapid discrimination between the aadA1 and aadA2 genes on the basis that the RH51 primer bound exclusively to the aadA2 gene.  相似文献   

2.
Reports on the internationally emerging significance of multiresistant zoonotic Salmonella in animals and man prompted studies to estimate the significance of multiresistant Salmonella enterica subspecies enterica serotype Typhimurium (S. Typhimurium) phage type DT104 of animal origin in Hungary. A collection of 231 strains (primarily of goose, turkey, poultry and porcine origin from the years 1997-1998) was tested for resistance against 7 selected antibiotics (ampicillin, chloramphenicol, enrofloxacin, nalidixic acid, streptomycin, tetracycline and sulphamethoxazole). Strains with resistance against 3 or more were defined as multiresistant. All strains were phage typed using Felix-Callow's S. Typhimurium phage typing system, and 91 of them (suspect DT104) were also typed according to Anderson's definitive typing (DT) system. In this study, 14% of animal strains from 1997-1998 was classified as DT104, for which turkey, pig and duck seemed to be the main carriers, and the multiresistant non-DT104 strains represented a further 6% of this collection. The prevalence of DT104 was highest among strains of turkey origin (50%), followed by strains of pig (29%), chicken (25%), duck (19%), and goose (3%) origin. The other DT104 related phage types (DT12 and U302) were only detected in the case of 4 strains (2 of porcine, and one each of turkey and of goose origin). The DT104 corresponded to the Felix-Callow types 2/3 or 2c/3 in each case, except in the case of 3 turkey strains where they corresponded to type 35/3. Nalidixic acid resistance was detected in all multiresistant turkey strains and in some of other animal origin but none of these strains were resistant to enrofloxacin. A retrospective analysis (based on the above relationship) indicated that S. Typhimurium strains corresponding to DT104 could be present and increase in the Hungarian farm animal population from about 2% to 20% between 1985 and 1990, in a manner similar to the emergence of human DT104, as reported elsewhere (Pászti et al., 2000). The 91 suspect DT104 strains were also tested for plasmid profile and for spvC gene indicating the presence of the large serotype specific plasmid (Ssp). No characteristic plasmid profile could be attributed to S. Typhimurium DT104. The serovar-specific large plasmid was detected by PCR for spvC in 100% of DT104 strains and in 77% of the non-DT104 strains. The virulence of two DT104 strains was tested in orally infected day-old chicks and compared with virulence of 4 non-DT104 strains. Higher colonizing virulence of DT104 strains could be established as compared to the other strains.  相似文献   

3.
A 1.6kb DNA fragment identified by random amplifiable polymorphic DNA differentiation (RAPD) from a Salmonella enterica serotype Typhimurium phage type DT104 isolate was used to investigate the prevalence of the region in 160 DT104 isolates, 83 other epidemiological important S. Typhimurium phage types and 20 strains selected from 17 other Salmonella serotypes. PCR screening tests using two different primer-sets derived from the RAPD fragment's nucleotide sequence showed that 76% of the 160 DT104 isolates investigated, including subtypes DT104A, DT104B, DT104B low, DT104H and DT104L, reacted positively. High sensitivity was shown for DT104 strains expressing at least the penta-resistance pattern ACSSuT (97% of 104 strains tested). DT104 susceptible strains showed only a sensitivity of 35% (17 strains tested). In contrast, 83% of the 83 strains from the other S. Typhimurium phage types reacted negatively. Strains from five out of the 17 other serotypes showed a positive signal with one primer-set. The other primer-set exhibited only a positive reaction with one S. Dublin isolate. The analysis of a 2415bp extended sequence revealed homologies to genes encoded by Escherichia coli O157:H7 prophages, suggesting that the described region contains genes of a prophage specific for DT104 and related phage types.  相似文献   

4.
Salmonella enterica serovar Typhimurium (S. Typhimurium) isolated and identified from swine were subjected for the analysis of antibiotic resistance pattern and clinically important class 1 and 2 integrons. In addition, S. Typhimurium isolates exhibiting ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline and florfenicol (ACSSuTF) resistance pattern as described in most Salmonella enterica serotype Typhimurium definitive type 104 (DT104) were characterized by polymerase chain reaction. All the isolates were resistant to more than four antibiotics and showed the highest resistance to streptomycin (94.1%), followed by tetracycline (90.1%), ampicillin (64.7%), chloramphenicol (56.8%) and gentamicin (54.9%). MIC value for the ten isolates ranged between 0.125-2 mug/ml for ciprofloxacin. Among the beta-lactams used, only one of the isolate exhibited resistance to ceftiofur (MIC 8 microg/ml). Sixty eight percent of these multi drug resistance (MDR) S. Typhimurium isolates carried clinically important class 1 integron with 1kb (aadA) and/or 2kb (dhfrXII-orfF-aadA2) resistance gene cassettes. This study reports the increasing trend of multi drug resistance (MDR) S. Typhimurium with clinically important class 1 integron in pigs. In addition, emergence of the ACSSuTF-type resistance in S. Typhimurium PT other than DT104 may limit the use of resistance gene markers in its detection methods by PCR.  相似文献   

5.
We studied 232 Salmonella strains from horses with salmonellosis in The Netherlands, isolated in the period from 1993 to 2000 in order to provide insight in the dynamics of sero-, phage types (pt) and antibiotic susceptibilities over time. The strains were tested for susceptibility to seven antimicrobial agents using the agar diffusion method. In addition, the isolates were sero typed and Salmonella enterica subspecies enterica Typhimurium and Enteritidis strains were further phage typed. S. Typhimurium strains of phage type 506 and 401 (both classified as DT 104 in the English phage typing system) were additionally tested for their susceptibility to chloramphenicol (C), streptomycin (S) and sulfonamides (Su). Resistance was common against tetracycline and ampicillin. Most strains were susceptible to enrofloxacin (Enr) and ceftiofur (Cef). Resistance to tetracycline (T), kanamycin (K), ampicillin (A) and trimethoprim/sulfonamide (Sxt) combinations decreased from 1993 to 2000, whereas the resistance to gentamicin (G), ceftiofur and enrofloxacin was stable over time. S. Typhimurium was the predominant serovar and showed more (multiple) resistance compared to other Salmonella serovars. Sixteen different resistance patterns were found, with resistance to T alone and the combination of ACSSuT and AKSxtT being the most common. The multiresistant S. typhimurium phage type 506 (DT 104) was the most common phage type isolated from horses and most of these strains showed the pentadrug resistance pattern ACSSuT. The S. Typhimurium phage type 401 (DT 104) was also found frequently with an ASSuT resistance pattern. The most common S. Typhimurium phage types in horses corresponded with those found in humans, pigs and cattle in the same period in The Netherlands.  相似文献   

6.
To study the genetic characteristics of DT104 strains of Salmonella Typhimurium and the prevalence of Salmonella Genomic Island (SGI1) in Hungary, 140 recent Salmonella strains of food and animal origin were examined. For the first time in Hungary, the SGI1 was found in 17 out of 59 S. Typhimurium isolates (all proven to be DT104 phage type). These 17 strains were then subtyped by pulsed-field gel electrophoresis (PFGE) into 6 pulsotypes which were less correlated with the geographic origin than with the animal species of origin.  相似文献   

7.
Forty-two Salmonella isolates obtained from diseased swine were genetically characterized for the presence of specific antimicrobial resistance mechanisms. Twenty of these isolates were characterized as S. Typhimurium DT104 strains. Pulsed-field gel electrophoresis was used to determine genetic relatedness and revealed 20 distinct genetic patterns among the 42 isolates. However, all DT104 isolates fell within 2 closely related genetic clusters. Other Salmonella isolates were genetically grouped together according to serotype. All DT104 isolates displayed the penta-resistance phenotype to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline. Resistance to sulfamethoxazole, tetracycline, streptomycin, kanamycin, and ampicillin was most common among the non-DT104 Salmonella isolates. All DT104 strains contained 2 chromosomal integrons of 1000 and 1200 base pairs. The DNA sequencing revealed that the 2 integrons contained genes encoding a resistance to streptomycin and ampicillin, respectively. None of the non-DT104 strains showed the same pattern, although several strains possessed integrons of 1000 base pairs or larger. However, the majority of non-DT104 Salmonella strains did not possess any integrons. Two Salmonella isolates displayed tolerance to the organic solvent cyclohexane, indicating the possibility that they are overexpressing chromosomal regulatory genes marA or soxS or the associated multidrug efflux pump, acrAB. This research suggests that integrons contribute to antimicrobial resistance among specific swine Salmonella serotypes; however, they are not as widely disseminated among non-Typhimurium swine Salmonella serotypes as previously thought.  相似文献   

8.
In this study we examined the extent of biofilm formation in field strains of Salmonella enterica serovar Typhimurium (S. Typhimurium), an important foodborne pathogen. Ninety-four field strains of S. Typhimurium were tested for their ability to form biofilm and components contributing to its formation. Most S. Typhimurium strains were highly capable of biofilm formation except for strains of phage type DT2 originating from pigeons. The most efficient biofilm forming strains were those of phage type DT104 positive for Salmonella genomic island 1 (SGI1). A comparison of SGI1 positive and negative strains indicated that the increased biofilm formation of SGI1 positive strains was associated with the presence of this genomic island. Finally, in five strains we found an alternative strategy of biofilm formation independent of curli fimbriae and cellulose production but solely dependent on an overproduction of capsular polysaccharide. Due to a mucoid and brown appearance on Congo Red agar we designated these strains as belonging to the SBAM (smooth brown and mucoid) morphotype.  相似文献   

9.
Multidrug-resistant Salmonella enterica serovar Typhimurium phage type DT104 has emerged during the last decade as a global health problem because of its involvement in diseases in animals and humans. Multidrug-resistant DT104 strains are mostly resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides and tetracyclines (ACSSuT resistance type). The genes coding for such resistances are clustered on the chromosome. This paper reviews new developments in the characterization of S. enterica Typhimurium DT104, its chromosomal antibiotic resistance genes and their spread among other S. enterica Typhimurium phage types and other S. enterica serovars, the development of specific detection methods, virulence characteristics, and the evolution of multidrug-resistance with regard to the emergence of quinolone resistance.  相似文献   

10.
Salmonella bacteriophages seem to mediate horizontal transfer of virulence functions among Salmonella strains in two different ways: by general transduction and also by lysogenic conversion. The majority of wild phages isolated from Salmonella strains belong to the P22 like phages and were able to transduce. Our data show that the lysogenic conversion is generally accompanied by changes in the susceptibility to the typing phages used for epidemiological purposes. Similar phage type conversions to S. Typhimurium DT104 could be detected upon lysogenization with two other S. Typhimurium strains. For some S. Typhimurium strains the typical phage pattern is actually associated with alterations of virulence characteristics. For example, all tested wild type isolates of phage types DT49 and DT204 were found to be SopE phi-lysogens. The Anderson typing phages interfere with the prophages and/or cryptic phages and so the complex genetic short-term evolution can be demonstrated in the lab. This is one reason for the successful application of phage typing in Salmonella epidemiology since the 50s.  相似文献   

11.
The present study is the first conducted in Spain to estimate the bacteriological herd prevalence of Salmonella enterica in fattening units and to describe the Salmonella serovar diversity on these farms using a sample representative of the entire swine population. For this purpose, 10 faecal samples were collected from 10 different pens containing pigs close to market weight in a total of 232 fattening units. Total sample size was proportionally distributed according to the fattener census in each of the regions of the country and all the samples were examined by culture of 25 g of faecal material. One hundred (43.1%) farms had at least one Salmonella-positive sample (95% CI: 37-49.1%). Salmonella enterica was detected in 290 (12.5%) pooled faecal floor samples (95% CI: 11.2-13.8%). The apparent herd prevalence of salmonellosis was similar among multi-site, finishing and farrow to finish farms. Overall, 24 different serovars were identified, with S. Typhimurium, S. Rissen and S. Derby being the most common both at herd and sample level. Results of phage typing were available for the 91 isolates of S. Typhimurium. A total number of 10 different phage types were identified, with DT 193 being the most frequent. Phage types DT 104, DT 104b and DT U302, which have been associated with several multi-resistant patterns, accounted for 23% and 29% of the Typhimurium total isolates or Typhimurium infected farms respectively.  相似文献   

12.
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13.
This study aimed to investigate the relatedness of porcine Salmonella enterica subsp. enterica (S.) serovar Typhimurium strains isolated in Southern Brazil. Sixty-six isolates from pigs belonging to three commercial companies were submitted to phage typing, XbaI-macrorestriction (PFGE), IS200 hybridization, rep-PCR, antimicrobial susceptibility testing, and PCR assay targeting the spvR region. All strains presented a unique rep-PCR pattern and 63 strains had a common IS200 profile. One pulse-type (XA) was the most prevalent (39/66 strains) and included strains of phage types DT177, DT192, DT194 and RDNC. The spvR region was detected in three strains, which harboured plasmids of 90 kb. High rates of tetracycline, sulfonamide and streptomycin resistance were found. Isolates from farms located in different geographic regions but associated to the same commercial companies clustered together and presented a common resistance profile. Results suggested that clonal groups of S. Typhimurium are present in pig commercial companies in Southern Brazil.  相似文献   

14.
The discriminatory power of four different DNA based typing methods was tested for the molecular subtyping of Salmonella Typhimurium phage type DT104 isolates. German DT104 strains (n = 133) originating from slaughter pigs were analysed by plasmid profiling, and 32 of them by pulsed-field gel electrophoresis (PFGE) using the restriction enzymes XbaI, SpeI or BlnI, random amplification of polymorphic DNA (RAPD) using 13 different primers and IS200 typing. A resulting subtyping scheme was obtained which is based on the most discriminatory power of the individual methods i.e. plasmid profiling and PFGE with all three enzymes. The index of discrimination obtained by the subtyping scheme was 0.909 closely approaching the maximum value of one. Although minor differences occurred in the molecular DNA pattern of single DT104 strains, a dominating subtyping pattern was observed confirming other studies which showed, that S. Typhimurium DT104 isolates are highly clonal.  相似文献   

15.
A total of 153 isolates of Salmonella Typhimurium derived from food-producing animals in Japan between 2002 and 2005 were investigated for antimicrobial resistance and phage types related to definitive phage type 104 (DT104). The predominant resistance type was resistance to ampicillin, dihydrostreptomycin, kanamycin, and oxytetracycline in bovine (45.2%, 48/104) and resistance to dihydrostreptomycin and oxytetracycline in porcine isolates (58.7%, 27/48). DT104-related phage type was found in 32 of 104 bovine isolates, two of 48 porcine isolates, and one of eight isolates from poultry, showing that the proportion of the phage type in S. Typhimurium isolates from cattle and pigs significantly (P<0.01) decreased from 71.9% and 31.4% in 1999-2001 to 30.8% and 4.1% in 2002-2005, respectively.  相似文献   

16.
In a representative study, 380 manure samples of pig farms distributed all over Bavaria (Germany) were screened for the presence of Salmonella spp. at the time of manure application to soil using methods adapted to DIN EN ISO 6579. The isolates were tested according to DIN 58940 for their susceptibility towards 26 antimicrobial substances - such substances partly administered in animals, but mainly used in human therapy. Six out of 380 manure samples and, in addition, the only separated liquid manure sample examined, contained Salmonella isolates. Serotypes represented S. Typhimurium (n = 5), S. Derby (n = 1) and S. Infantis/S. Serogroup C1-(6,7:r:-)-form (each n = 1). Within the serovar S. Typhimurium, the most common phage type was DT104 (n = 3). All Salmonella isolates originated from 'big' farms (>30/45 sows on combined/breeding farms or >220 fattening pigs). Four out of six manure samples contained resistant isolates; all resistant Salmonellae were multi-resistant. Two out of three DT104-isolates showed the typical penta-resistance pattern often found in S. Typhimurium DT104, which was, furthermore, supplemented by other resistances. One Escherichia coli isolated together with a phage type DT104 S. Typhimurium also expressed the same penta-resistance pattern.  相似文献   

17.
This study aimed to investigate the relatedness of porcine Salmonella enterica subsp. enterica (S.) serovar Typhimurium strains isolated in Southern Brazil. Sixty-six isolates from pigs belonging to three commercial companies were submitted to phage typing, XbaI-macrorestriction (PFGE), IS200 hybridization, rep-PCR, antimicrobial susceptibility testing, and PCR assay targeting the spvR region. All strains presented a unique rep-PCR pattern and 63 strains had a common IS200 profile. One pulse-type (XA) was the most prevalent (39/66 strains) and included strains of phage types DT177, DT192, DT194 and RDNC. The spvR region was detected in three strains, which harboured plasmids of 90 kb. High rates of tetracycline, sulfonamide and streptomycin resistance were found. Isolates from farms located in different geographic regions but associated to the same commercial companies clustered together and presented a common resistance profile. Results suggested that clonal groups of S. Typhimurium are present in pig commercial companies in Southern Brazil.  相似文献   

18.
As a part of a nationwide programme to survey and control salmonella in pig herds, a microbiological survey of 1363 pig herds was performed in Denmark. A total of 13 468 slaughter pigs were examined at slaughter by culture of 5 g of caecal contents. Overall, 30 different serotypes of Salmonella enterica were isolated from 832 pigs (6.2%). The predominant serotype was S. Typhimurium, comprising 536 (64.4%) of the isolates. Four hundred and forty-eight isolates of S. Typhimurium were examined by phage typing, resulting in detection of 17 different phage types (definitive types, DT) with DT12 being the most frequent (49.1%).

Salmonella enterica was found in 302 herds (22.2%), S. Typhimurium was found in 61.1% of these. 279 (23.1%) large herds (producing more than 2600 slaughter pigs per year) were found to be salmonella positive compared with 23 (14.7 %) small herds (annual production of 500 to 550 slaughter pigs). Practical constraints in the study design did not allow for a firm conclusion on the interplay among herd size, geographical location and occurrence of salmonella.

In 284 of 302 infected herds (94.0%) only one serotype was detected. Infections with two different serovars were seen in 18 herds (6.0%).  相似文献   


19.
Fourteen and 22 each of Salmonella Enteritidis and Salmonella Typhimurium (S. Typhimurium) were isolated from animals from 1983 to 1999 in Korea and tested for their antibiotic resistance patterns, phage types and resistance gene patterns. S. Typhimurium isolates were highly resistant to streptomycin, sulfisoxazole and tetracycline, 95, 95 and 86%, respectively. The incidence of multiple antibiotic resistance (resistant to more than two drugs tested) of S. Typhimurium isolates was extremely high (100%) comparing to S. Enteritidis isolates (21%). Two of the five ACSSuT (ampicillin, chloramphenicol, streptomycin, sulfisoxazole and tetracycline) resistant type S. Typhimurium isolates were phage type definitive type 104 (DT104).For the detection of resistance related genes in S. Enteritidis and S. Typhimurium isolates, particularly ACSSuT type S. Typhimurium, antibiotic resistance genes, cmlA/tetR, bla(PSE-1) and bla(TEM), and genus Salmonella specific gene, sipB/C, were amplified using four pairs of primers in a hot-start multiplex polymerase chain reaction (PCR). Two Korean isolates of S. Typhimurium DT104 showed bla(TEM) amplicons instead of bla(PSE-1) for the ampicillin resistance and they were susceptible to florfenicol. The multiplex PCR used in this study was useful in characterization of multiple drug resistant Salmonella isolates, especially ACSSuT type S. Typhimurium, and identification of beta-lactamase gene distribution among Salmonella isolates.  相似文献   

20.
A total of 1,000 rectal samples were collected from rabbits coming from 25 rabbit farms in southern Italy. All samples were processed for isolation of Salmonella spp. by standard culture method based on the ISO 6579:2002 method. Salmonella spp. was isolated from 1/25 rabbit farms analyzed. In particular, four out of 1,000 rectal swab samples, taken from young rabbits, were serotyped as S. Typhimurium and phage typed as S. Typhimurium DT104. All the isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline (ACSSuT pentaresistance type). The findings of the present study suggest the rabbit as potential carrier of S. Typhimurium DT104.  相似文献   

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