Plasmid profile analysis, phage typing, and antibiotic sensitivity of Salmonella dublin from clinical isolates in the United States.

One hundred clinical isolates of Salmonella choleraesuis subsp. choleraesuis serovar dublin (Salmonella dublin) were examined for phage sensitivity, antibiotic resistance patterns, and plasmid content. Computer analysis of the lysis patterns observed by using 27 typing phages divided the S. dublin isolates into 26 groups. One lytic pattern (Designated pattern 16) contained 52% of the isolates examined whereas 16 isolates had unique patterns, and nine patterns had fewer than ten members. Although 14 antibiotic resistance patterns were observed among the 100 isolates, 79% of the isolates grouped in three major patterns. Seven plasmid groups were identified and designated A-G based on the large plasmids found in the isolates. Of the 100 isolates, 28 contained the plasmid profile of Group A, 28 were Group B, 7 were Group C, 34 were Group D, and 1 isolate each was observed in Groups E, F, and G. The strong association between antibiotic resistance pattern and plasmid type suggest that the drug resistance genes are plasmid borne.     

Prevalence and persistence of Salmonella in broiler chicken flocks.

Cecal contents of 2,345 broiler chickens consisting of 28 flocks originated from 12 farms were examined for the prevalence of Salmonella to know the actual status of infection with Salmonella in the chicken flocks. Salmonella was isolated from 336 (14.3%) samples. From these isolates, eight serovars were identified. Of the 336 Salmonella isolates, 242 (72.0%) were serotyped as S. Blockley, 60 (17.9%) S. Hadar, 15 (4.5%) S. Bredeney, nine (2.7%) S. Schwarzengrund, four (1.2%) S. Anatum, three (0.9%) S. Enteritidis, two (0.6%) S. Ohio, and one (0.3%) S. Livingstone. The same serovars of Salmonella were repeatedly found in the chickens from the same farms. S. Typhimurium and S. Enteritidis were detected in pooled broken eggshell samples collected from the hatchery. Analysis of plasmid profiles revealed 11 patterns of S. Blockley and seven patterns of S. Hadar. Strains of the same plasmid profiles of S. Blockley were isolated repeatedly from the same farm over one year after the first isolation.     

循环水养殖模式对水体微生物、蛋鸭粪便微生物和土壤微生物的影响

试验旨在研究循环水养殖模式对水体微生物、蛋鸭粪便微生物和土壤微生物的影响。分别采集样品检测饮水管、戏水池、排水沟、各级消化池的水样和鸭舍内粪样、运动场粪样及周边土壤样品,采用平板计数法检测微生物数量。结果表明:(1)与排水沟的微生物数量相比,各级消化池和饮水管的大肠杆菌数分别降低28.13%、32.42%、40.98%和33.94%,"沙门+志贺"氏菌数分别降低13.75%、53.13%、82.5%和79.38%,均差异极显著(P<0.01);(2)与鸭舍内粪便微生物数量相比,运动场的大肠杆菌数和"沙门+志贺"氏菌数分别增加3.08%和2.29%,但差异不显著(P>0.05),土壤的大肠杆菌数和"沙门+志贺"氏菌数分别降低9.00%和3.70%,均差异不显著(P>0.05)。由此可知,循环水养殖模式能显著减少各级消化池和饮水管中病原微生物的数量。     

Molecular typing of VapA-positive Rhodococcus equi isolates from Jeju native horses, Korea

We recently demonstrated the presence of virulence-associated protein antigen (VapA)-positive Rhodococcus equi in Jeju Island, Korea. These bacteria contained one of two distinct plasmid types, a 90-kb type II plasmid, which has been found in isolates from the native Kiso horses of Japan, and a new variant, a 90-kb type V plasmid. However, the genotypic characters of the VapA-positive R. equi from Jeju native horses and their environments are poorly understood. Ninety-eight isolates from soil samples and 89 isolates from fecal samples were collected from five farms that breed or have bred Jeju native horses, and were tested for the presence of VapA by immunoblotting and PCR. Of the 98 soil isolates and 89 fecal isolates, seven and 13 were VapA-positive R. equi, respectively. In 2003, two Jeju foals died suddenly and were brought to the Faculty of Veterinary Medicine, Cheju National University, for postmortem examination. Pure cultures of R. equi were isolated from the lung lesions of both foals. Of the 16 clinical isolates, 14 were VapA-positive R. equi. Of the 34 VapA-positive clinical and environmental isolates, 16 contained the 90-kb type II plasmid and 18 contained a 90-kb type V plasmid. Pulsed-field gel electrophoresis (PFGE) patterns of the VapA-positive isolates from Jeju horses and Kiso horses, containing the 90-kb type II plasmid, were compared and formed two distinct groups. Furthermore, 18 virulent isolates containing the 90-kb type V plasmid formed two distinct PFGE groups (of 16 and two isolates). These results demonstrate that two virulence plasmid types are widespread in R. equi in Jeju native horses. However, there is little diversity in the PFGE patterns of virulent isolates, suggesting the clonal spread of virulent R. equi. The PFGE pattern of the virulent R. equi isolates from Jeju native horses in Korea is not identical to those of Kiso native horses in Japan.     

Plasmid profile analysis of salmonellae in a large-animal hospital

The plasmid profiles of salmonellae isolated from the patients and environment of the Purdue Large Animal Hospital were used as markers to identify strains and to assess the impact of improvements in hospital operation on nosocomial salmonellosis. Plasmid profile analysis proved to be more sensitive than either serotyping or antimicrobial susceptibility testing in identifying Salmonella isolates. During June and July 1983, 29 of 34 salmonellae isolated were one of three strains with distinct plasmid profiles: one S. typhimurium var. Copenhagen, and two S. muenchen. Each of these strains was isolated from at least one patient and two environmental sites, suggesting the possibility that infections were hospital-acquired. Patient and environmental sampling was repeated in June and July 1984, after improvements had been made in hospital traffic flow and sanitation. In contrast to 1983, only seven isolates, representing six strains not seen previously, were obtained in 1984. None of these strains was isolated from both patient and environmental sources. The results indicate that the high incidence of clinical salmonellosis in 1983 was largely due to nosocomial infections. The decrease in the incidence of salmonellosis and the absence of the 1983 strains from samples taken in 1984 were presumed to be due to improvements made in hospital operation. This study demonstrates the value of plasmid analysis in monitoring nosocomial salmonellosis in a veterinary hospital.     

鱼塘生态体系中大肠埃希菌和沙门菌的耐药性研究

为了解鱼塘生态体系大肠埃希菌和沙门菌的耐药情况,从广东省佛山某鱼塘随机采集草鱼及生活圈的水土样品中(包括鱼肠内容物、鱼塘底泥、鱼塘水)分离出47株大肠埃希菌和23株沙门菌.采用纸片扩散法(Kirby-bauer,KB)对分离菌株进行了15种抗生素的敏感性试验,结果显示100%的菌株均耐1种及1种以上的抗生素多表现出对氨...     

Investigation and characterization of the frozen feeder rodent industry in Texas following a multi-state Salmonella Typhimurium outbreak associated with frozen vacuum-packed rodents

A multi-state outbreak investigation of Salmonella Typhimurim cases associated with pet snakes and the frozen vacuum-packed rodents used to feed them identified a Texas frozen feeder rodent facility (Supplier A) as the source of the Salmonella-infected frozen rodents. Texas authorities collected samples directly from Supplier A. Seven Salmonella-positive samples out of 49 environmental swabs were found and one adult mouse out of 88 frozen feeder rodents was Salmonella-positive by culture. No Salmonella strains were isolated from rodent feeds. The pulsed-field gel electrophoresis (PFGE) subtype patterns of S. Typhimurium isolates from feeder rodent and environment samples were indistinguishable from the outbreak strain isolated from humans. A follow-up investigation was performed on all additional feeder rodent facilities identified in Texas. Salmonella was isolated at one of four facilities; seven of 100 rodent samples were positive for Salmonella at this facility. The serotype S. I 4,[5],12:i:- was isolated from seven feeder rodent samples, and PFGE patterns of the seven isolates were indistinguishable. As observed in the initial outbreak investigation, no Salmonella were cultured from rodent feeds at any of the facilities. The feeder rodent industry is an insufficiently recognized industry in the United States. Outbreak investigation and testing of additional feeder rodent facilities in Texas indicate that further evaluation of feeder rodent facilities as a source of Salmonella for pet snakes and humans is warranted.     

Prevalence of virulent Rhodococcus equi in soil from five R. equi-endemic horse-breeding farms and restriction fragment length polymorphisms of virulence plasmids in isolates from soil and infected foals in Texas.

Rhodococcus equi isolates (462) obtained from 64 soil samples collected on 5 R. equi-endemic horse-breeding farms and isolates from 100 infected foals in Texas were examined to determine the prevalence and genotypic diversity of virulence-associated plasmids. Isolates were tested for the presence of 15-17-kDa virulence-associated protein antigens (VapA) by immunoblotting and virulence-associated plasmids by PCR. Plasmid DNAs were isolated and analyzed by digestion with restriction endonucleases for estimation of size and comparison of polymorphisims. Rhodococcus equi were isolated from soil of all 5 farms; however, virulent R. equi were only isolated from 3 of the 5 farms and represented 18.8% (87 of 462) of total isolates. Of the 87 virulent soil isolates, 56 (64.5%) contained an 85-kb type I plasmid, 23 (26.4%) an 87-kb type I plasmid, 7 (8%) a newly defined 85-kb type III plasmid (Tx 43), and 1 (1.1%) a newly defined 85-kb type IV plasmid (Tx 47). Of the 100 isolates from infected foals, 96 were virulent. Of the 96 virulent isolates, 51 (53.1%) contained an 85-kb type I plasmid, 39 (40.6%) an 87-kb type I plasmid, 4 (4.2%) an 85-kb type III plasmid (Tx 43), and 2 (2.1%) an 85-kb type IV plasmid (Tx 47). There are at least 4 different R. equi virulence-associated plasmids in Texas, 2 of which have not previously been described. Based upon virulence plasmid typing, there is geographic diversity among isolates of R. equi from clinical and environmental samples on horse-breeding farms in Texas. There is not a strong correlation between the presence of virulent R. equi in farm soils and the R. equi disease status of those farms.     

Plasmid analysis and epidemiology of Salmonella enteritidis infection in three commercial layer flocks.

Ninety-six S. enteritidis isolates obtained from three commercial layer flocks in 1988-90 were examined following DNA extraction, restriction enzyme digestion, and gel electrophoresis for plasmid size profiles and restriction fragment length polymorphisms (RFLPs). The S. enteritidis isolates from the three flocks had three, eight, and two different plasmid profiles, respectively. Only four isolates from one flock lacked plasmids. A 36-megadalton (mDa) (54-kilobase) plasmid was present in 73% of the isolates, either alone or in combination with other plasmids. Isolates with only the 36-mDa plasmid had identical RFLPs. The diversity of plasmid profiles was greater than that of phage-types among isolates from the three flocks: 12 unique plasmid profiles vs. four phage-types. Mixed infections with S. enteritidis strains having distinct plasmid profiles occurred in all three flocks. Reinfection of these flocks in 1990 with one or more of the strains obtained earlier was evident, because some of the original isolates and the 1990 isolates had matching plasmid profiles and were of the same phage-types. Isolates from both environmental and tissue samples, examined from one flock, were found to share the same plasmid profile and phage-type.     

Genetic diversity of Clostridium perfringens isolated from healthy broiler chickens at a commercial farm

Clostridium perfringens is an important commensal and bacterial pathogen of many animal species. It has particular significance in poultry, where it may cause necrotic enteritis. Our objective was to characterize the population diversity of C. perfringens colonizing healthy birds, and to observe how diversity changed over time. Isolates were obtained from broiler chicken cecal samples in two barns on a single farm, on days 7, 14, 22, 27, 30 and 34 of a single 42-day rearing cycle. Bacitracin was used as a feed additive in one of the barns and withdrawn from the second barn for the duration of the experiment. Each isolate was typed using pulsed-field gel electrophoresis (PFGE) using SmaI restriction endonuclease. A total of 205 cecal isolates from 49 birds were typed, as well as 93 isolates from the barn environment (bedding, drinking water and feces). Eight major PFGE types and 17 subtypes were found in the 298 total isolates. The results show that an optimal sampling strategy would involve a large number of birds, with only a few isolates sampled per bird. The diversity of C. perfringens in this study appears to be low within a single bird, and increases as the bird matures. There was no significant difference in genetic diversity between the two barns. In addition, isolates from fresh fecal samples appear to represent the cecal C. perfringens population accurately, although this was not proven statistically. Antimicrobial susceptibility testing was performed on selected isolates (n=41) representing a cross-section of PFGE types. Based on minimum inhibitory concentration distributions, 95% of the isolates tested were deemed resistant to bacitracin, with a 16 microg/mL breakpoint. Three new cpb2 (beta2 toxin gene) variants were found in the study.     

Comparison of antimicrobial resistance in generic Escherichia coli and Salmonella spp. cultured from identical fecal samples in finishing swine

The objectives of this study were to investigate the associations between antimicrobial resistance patterns in generic Escherichia coli and Salmonella spp. isolates recovered from identical pen pooled fecal samples, and to evaluate potential clustering of multiple isolates of these organisms within identical fecal samples. Up to 5 generic E. coli (n = 922 isolates) and Salmonella spp. (n = 922 isolates) isolates were obtained from each of 188 pen pooled fecal samples that had been collected from 45 finishing swine farms in Alberta in 2000, and tested for susceptibility to 15 antimicrobials. No isolates of either organism were resistant to 3rd generation cephalosporins or fluoroquinolones, which in Canada are considered antimicrobials of very high importance to human health. Approximately twice as many generic E. coli isolates as Salmonella spp. isolates were resistant to at least 1 antimicrobial. In addition, E. coli isolates showed more multidrug-resistance patterns. No significant association was observed between the resistance phenotypes of Salmonella spp. and E. coli at the fecal sample level. More clustering at the sample level was observed for proportions of antimicrobial resistance (AMR) in Salmonella spp. isolates than E. coli indicating that in future studies it might be sufficient to test fewer than 5 Salmonella spp. isolates per sample.     

Molecular epidemiology and antimicrobial resistance of Salmonella typhimurium DTI04 on Ontario swine farms.

This study was conducted to examine antimicrobial resistances, plasmid profiles, and pulsed-field gel electrophoresis patterns of 80 Salmonella Typhimurium (including var. Copenhagen) DT104 strains (including DT104a and DT104b) recovered from pig and environmental fecal samples on 17 swine farms in Ontario. No resistance was observed to amoxicillin/clavulanic acid, apramycin, carbadox, cephalothin, ceftriaxone, ceftiofur, cefoxitin, ciprofloxacin, nalidixic acid, trimethoprim, and tobramycin. However, the isolates exhibited resistance against 4 to 10 antimicrobials with the most frequent resistance being to sulfonamides (Su), ampicillin (A), streptomycin (S), spectinomycin (Sp), chloramphenicol (C), tetracycline (T), and florfenicol (F). Thirteen distinct resistance patterns were determined but 88% of isolates shared the typical resistance pattern "ACSpSSuT." Twelve different plasmid profiles were observed; the 62 MDa virulence-associated plasmid was detected in 95% of the isolates. The 2.1 MDa plasmid was the second most frequent one, which was harbored by 65% isolates. The isolates were classified into 23 distinct genotypes by PFGE-SpeI + BlnI when difference in at least one fragment was defined as a distinct genotype. In total, 39 distinct "types" were observed when defining a "type" based on the combination of antimicrobial resistance, plasmid pattern, and PFGE-SpeI + BlnI for each isolate. The highest diversity was 0.96 (95% CI: 0.92, 0.96) for the "type" described above followed by 0.92 (95% CI: 0.88, 0.93) for PFGE-SpeI + BlnI. The diversity of DT104 isolates indicates there might be multiple sources for this microorganism on swine farms. This knowledge might be used to track these sources, as well as to study the extent of human salmonellosis attributed to pork compared to food products derived from other food-producing animals.     

Rhodococcus equi virulence plasmids recovered from horses and their environment in Jeju, Korea: 90-kb type II and a new variant, 90-kb type V

Rhodococcus equi was isolated from fecal and soil samples from four native Jeju horse farms and six Thoroughbred farms in Jeju, Korea. The isolates were examined for the presence of virulence-associated 15-17-kDa antigens (VapA) by colony blotting, using the monoclonal antibody 10G5, and for the gene encoding VapA by PCR. R. equi was isolated from all 36 soil samples collected from the 10 farms with between 5.0 x 10(2) and 7.5 x 10(4) colony-forming units (cfu) per gram of soil, and from 37 of 40 fecal samples with between 5.0 x 10(1) and 1.1 x 10 (5) cfu per gram of feces. Virulent R. equi was isolated from seven farms and appeared in 2.0% of isolates (10 of 508). Of the 10 virulent isolates, four contained a 90-kb type II plasmid, which has been found in isolates from the Kiso native horses of Japan, and the other six contained a new variant, which did not display the EcoRI and EcoT22I digestion patterns of the 10 representative plasmids already reported (85-kb types I, II, III, and IV; 87-kb types I and II; 90-kb types I, II, III, and IV). We designated the new variant as the "90-kb type V" plasmid, because its EcoRI digestion pattern is similar to that of the 90-kb type II plasmid. This is the first report of the prevalence of virulent R. equi in Jeju, Korea. The same virulence plasmid type is found in both Korean and Japanese isolates, providing insight into the origin, ancestry, and dispersal of native horses in Korea and Japan.     

Evaluation of herd sampling for Salmonella isolation on midwest and northeast US dairy farms

Epidemiologic investigations of Salmonella infections in dairy cattle often rely on testing fecal samples from individual animals or samples from other farm sources to determine herd infection status. The objectives of this project were to evaluate the effect of sampling frequency on Salmonella isolation and to compare Salmonella isolation and serogroup classification among sample sources on 12 US dairy farms sampled weekly for 7-8 weeks. Three herds per state were enrolled from Michigan, Minnesota, New York and Wisconsin based upon predefined herd-size criteria. Weekly samples were obtained from cattle, bulk tank milk, milk filters, water and feed sources and environmental sites. Samples were submitted to a central laboratory for isolation of Salmonella using standard laboratory procedures. The herd average number of cattle fecal samples collected ranged from 26 to 58 per week. Salmonella was isolated from 9.3% of 4049 fecal samples collected from cattle and 12.9% of 811 samples from other sources. Serogroup C1 was found in more than half of the samples and multiple serogroups were identified among isolates from the same samples and farms. The percentage of herd visits with at least one Salmonella isolate from cattle fecal samples increased with overall herd prevalence of fecal shedding. Only the three herds with an average fecal shedding prevalence of more than 15% had over 85% of weekly visits with at least one positive fecal sample. The prevalence of fecal shedding from different groups of cattle varied widely among herds showing that herds with infected cattle may be classified incorrectly if only one age group is tested. Testing environmental sample sources was more efficient for identifying infected premises than using individual cattle fecal samples.     

Prevalence and antibiotic resistance profiles ofSalmonella serotypes isolated from backyard poultry flocks in West Bengal,India

The present study was conducted to determine prevalence, virulence gene profile, serotyping, and antibiotic resistance patterns ofSalmonella in birds kept under the backyard system in West Bengal, India. The study also incorporated the detection ofSalmonella prevalence in their environment, including feed, drinking water, utensils, litter, dried manure under the house, soil, and eggs, which helped to formulate a biosecurity strategy. The study was conducted in 4 agro-climatic zones, such as the terai, new alluvial, red laterite, and coastal. Out of 360 samples, 22Salmonella isolates (6.1%) were identified.Salmonella were isolated from cloacal swabs of 6 birds (15%, n = 40), from 4 feed samples (10%, n = 40), 8 drinking water samples (20%, n = 40), and 4 eggs (10%, n = 40). Similar antigenic structure, nucleotide sequence (invA) ofSalmonella Enteritidis and Typhimurium, and randomly amplified polymorphic DNA banding patterns ofSalmonella Enteritidis were observed. It seems that the sameSalmonella isolate was present in feed sample, cloacal swabs, and eggs in the terai zone, whereas, it was found in drinking water, birds, and eggs in the new alluvial and in drinking water and birds in the coastal zone. A zone-specific biosecurity strategy was formulated based on the findings. The isolates were found to be resistant to chloramphenicol, ciprofloxacin, gentamicin, levofloxacin, norfloxacin, and oxytetracycline. None of the isolates possessed genes for major extended spectrum β-lactamases. Thus, the present study identified the source ofSalmonella contamination in the backyard chickens and their eggs in India with possible forms of biosecurity strategies. Our study was the first attempt in India to determine the prevalence, virulence gene profile, serotyping, and antibiotic resistance pattern ofSalmonella in backyard birds, including the environment and product.     

Effects of marketing stress on fecal excretion of Salmonella spp in feeder calves

Fecal samples were collected from 200 feeder-calves on farms in Tennessee, after assembly at a Tennessee auction market, and after transport to a Texas feedyard. A final fecal sample was collected from each calf after 30 days of feedyard confinement. The fecal samples were cultured for the presence of Salmonella spp. Salmonella isolates were serotyped and antimicrobial drug-resistance patterns determined. The number of calves fecal culture-positive for Salmonella spp increased from 0 on the Tennessee farms and auction market to 3/200 (1.5%) at entry into the Texas feedyard, and 16/200 (8%) after 30 days of feedyard confinement. Salmonella serotypes isolated and the number of isolates of each serotype were S reading (8), S cerro (4), S newbrunswick (3), S anatum (2), and S typhimurium (copenhagen; 2). All Salmonella isolates were resistant to 5 or more of 13 antimicrobial drugs tested. Salmonella reading isolates were resistant to 10 or 11 of 13 antimicrobial drugs. The results indicated that the calves could have been infected with Salmonella spp prior to or during the course of the study, and that marketing stress as they moved from farm through feedyard may have induced fecal excretion of salmonellae. In addition, the pattern of antimicrobial drug resistance in the Salmonella isolates was broad.     

Utilization of both phenotypic and molecular analyses to investigate an outbreak of multidrug-resistant Salmonella anatum in horses.

Phenotypic and molecular techniques, including antimicrobial susceptibility testing, plasmid analysis, and pulsed-field gel electrophoresis (PFGE) were used to characterize 15 isolates of multidrug-resistant (MDR) Salmonella anatum cultured during a 16 mo period from horses and a veterinary clinic environment. The isolates were resistant to multiple antimicrobial agents and could be placed into 4 groups based on their antimicrobial resistance patterns. The isolates contained multiple plasmids ranging in size from 2 to > 100 kb that could be grouped into 3 different plasmid profile patterns; these patterns did not correlate with the antimicrobial resistance groupings. Furthermore, antimicrobial resistance was conjugatively transferable. Digestion of genomic DNA from the 15 isolates with 3 different restriction endonucleases, SfiI, SpeI, and XbaI followed by PFGE revealed a highly conserved restriction endonuclease digestion pattern. In contrast, diverse banding patterns were observed with S. anatum obtained from other sources. These observations suggest that the MDR S. anatum isolates represent a common outbreak strain even though they possess different, albeit similar, antibiograms and plasmid profiles. The study showed that PFGE is a useful epidemiological tool for discriminating between unrelated and outbreak-related strains of S. anatum. In conclusion, epidemiological studies of outbreaks caused by MDR isolates of S. anatum should consist of both genotypic and phenotypic methods of analysis.     

A case of canine salmonellosis due to Salmonella infantis

A 7-year-old male dog kept outdoors manifested severe watery diarrhea with generalized weakness. Salmonella Infantis was isolated from a fecal sample and the dog recovered soon after medication with ampicillin, to which the isolate was highly sensitive. The present case was diagnosed as S. Infantis infection. Due to the importance of Salmonella in public health, soil samples were collected from the garden where the dog was kept and were examined for Salmonella, Some of them were positive for S. Infantis, however, no Salmonella was isolated from any soil samples collected after thorough disinfection of the surrounded environment.     

Isolation of virulent Rhodococcus equi from native Japanese horses

R. equi was isolated from soil samples obtained from the environment of seven native Japanese horse breeds (Hokkaido, Kiso, Noma, Misaki, Tokara, Miyako and Yonaguni) and from fecal samples collected from three native horse breeds (Hokkaido, Kiso and Misaki). Virulent R. equi at various levels (ranging from 0.5 to 12.9%) was isolated from the feces or soil environment of Hokkaido, Kiso and Misaki horses. Isolates were investigated both for the presence of 15- to 17-kDa antigens (virulence-associated protein antigens; VapA) by colony blotting, using the monoclonal antibody 10G5, and the gene of VapA by PCR. Plasmid DNAs extracted from positive isolates were digested with restriction endonucleases, and the digestion patterns of the plasmids of virulent isolates were divided into three types. Two of the three types (87-kb type II and 90-kb type I) had already been reported in Japanese isolates, and a new type (tentatively designated as 90-kb type II) had been found in isolates from Kiso horses. Six virulent R. equi isolates from the Hokkaido horses contained an 87-kb type II plasmid. Eight of 24 isolates from the Kiso horses contained an 87-kb type II plasmid, and the remaining 16 contained a 90-kb type II (a new type) plasmid. Two isolates from the Misaki horses contained a 90-kb type I plasmid. These results demonstrate the geographic difference in the distribution of virulence plasmids in R. equi isolates among native Japanese horses.     

Environmental surveillance for Salmonella enterica in a veterinary teaching hospital

OBJECTIVE: To evaluate the extent of environmental contamination with Salmonella enterica in a veterinary teaching hospital. DESIGN: Longitudinal study. SAMPLES: Environmental samples obtained from 69 representative locations within a veterinary teaching hospital by use of a commercially available electrostatic wipe. PROCEDURE: Environmental samples were obtained for bacteriologic culture, and antimicrobial susceptibility testing was performed on each environmental isolate. Environmental isolates were compared with isolates obtained from animals during the same period to investigate potential sources of environmental contamination. RESULTS: 54 S. enterica isolates were recovered from 452 (11.9%) cultured environmental samples. Five different serotypes were recovered; the most common serotypes were S. Newport and S. Agona. Within the 5 serotypes recovered, 10 distinguishable phenotypes were identified by use of serotype and antimicrobial susceptibility patterns. Of the environmental isolates, 41 of 54 (75.9%) could be matched to phenotypes of isolates obtained from animal submissions in the month prior to collection of environmental samples. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that environments in veterinary hospitals can be frequently contaminated with S. enterica near where infected animals are managed and fecal specimens containing S. enterica are processed for culture in a diagnostic laboratory. Bacteriologic culture of environmental samples collected with electrostatic wipes is an effective means of detecting contamination in a veterinary hospital environment and may be beneficial as part of surveillance activities for other veterinary and animal-rearing facilities.