A temporal study of Salmonella serovars in animals in Alberta between 1990 and 2001

Passive laboratory-based surveillance data from Alberta Agriculture Food and Rural Development were analyzed for common Salmonella serovars, prevalences, trends, and for the presence of temporal clusters. There were 1767 isolates between October 1990 and December 2001 comprising 63 different serovars, including 961 isolates from chickens, 418 from cattle, 108 from pigs, 102 from turkeys, and 178 from all other species combined. Salmonella Typhimurium, Heidelberg, Hadar, Kentucky, and Thompson were the 5 most frequently isolated serovars. Approximately 60% of the S. Typhimurium were isolated from cattle, whereas over 90% of the S. Heidelberg, Hadar, Kentucky, and Thompson were isolated from chickens. Salmonella Enteritidis was rarely isolated. There was an increasing trend in isolates from chickens, cattle, and pigs, and a decreasing trend in isolates from turkeys. Temporal clusters were observed in 11 of 15 serovars examined in chickens (S. Anatum, Heidelberg, Infantis, Kentucky, Mbandaka, Montevideo, Nienstedten, Oranienburg, Thompson, Typhimurium, and Typhimurium var. Copenhagen), 5 of 5 serovars in cattle (S. Dublin, Montevideo, Muenster, Typhimurium, and Typhimurium var. Copenhagen), and 1 of 3 serovars in pigs (S. Typhimurium). Short-duration clusters may imply point source infections, whereas long-duration clusters may indicate an increase in the prevalence of the serovar, farm-to-farm transmission, or a wide-spread common source. A higher concentration of clusters in the winter months may reflect greater confinement, reduced ventilation, stressors, or increased exposure to wildlife vectors that are sharing housing during the winter. Detection of large clusters of Salmonella may have public health implications in addition to animal health concerns.     

Antimicrobial susceptibility of Salmonella isolates recovered from calves with diarrhoea in Australia

OBJECTIVE To identify the common serotypes and antimicrobial resistance patterns of Salmonella spp. associated with diarrhoea in Australian dairy calves under the age of 6 weeks. DESIGN Cross-sectional study. METHODS Faecal samples were collected from outbreaks of diarrhoea in dairy and dairy beef calves less than 6 weeks old. Samples were screened for Salmonella using standard enrichment culture techniques. The antimicrobial susceptibility to 12 commonly used veterinary and human antimicrobials was assessed using the Kirby-Bauer disk diffusion method and the susceptibility profiles of dairy and dairy beef properties were compared using Fisher's exact test. RESULTS Salmonella ser. Dublin, S. ser. Typhimurium and S. ser. Bovismorbificans were the three most common salmonella serotypes isolated. The majority of properties had one serotype. Most of the Salmonella isolates were not resistant to any of the antimicrobials tested. No resistance was seen to amikacin and nalidixic acid, and only one isolate was resistant to ceftiofur or amoxicillin-clavulanic acid. The most common antimicrobial resistance was to streptomycin, ampicillin or combination sulfonamides. Multi-drug resistance was detected in S. ser. Anatum, S. ser. Bovismorbificans, S. ser. Muenster, S. ser. Newport and S. ser. Typhimurium. Isolates from dairy beef properties were more likely to be resistant to ampicillin, kanamycin, neomycin, sulfamethoxazole/trimethoprim and tetracycline (P < 0.05) and were more likely to exhibit multi-drug resistance. CONCLUSION The prevalence of antimicrobial resistance in Salmonella isolates from dairy calves in Australia is low compared with that reported overseas. From a human health perspective, resistance to antimicrobials used in the treatment of human salmonellosis was infrequent.     

Prevalence of Salmonella spp in selected birds captured on California dairies

OBJECTIVE: To determine the prevalence of Salmonella spp in wild birds commonly found on California dairies. DESIGN: Prospective study. ANIMALS: 7 selected species of birds were captured on 9 dairies in Kings and Tulare counties, California. PROCEDURE: Birds were captured (using traps and nets) and euthanatized, and the entire gastrointestinal tract was removed. Contents of the gastrointestinal tract were subjected to culture for Salmonella spp. RESULTS: 892 birds were captured, and Salmonella spp were isolated from 22 birds. The prevalence by dairy ranged from 0.7 to 16.7%, whereas the prevalence by bird species ranged from 1.2 to 3.2%. Cowbirds and English sparrows had the highest prevalence of Salmonella organisms. Five serotypes of Salmonella organisms were isolated, including Meleagridis, Montevideo, Muenster, Typhimurium, and an untyped serotype. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of our findings, birds that commonly inhabit California dairies harbor Salmonella organisms. However, because of the low prevalence of Salmonella organisms in birds and the Salmonella serotypes isolated, birds are not important reservoirs of Salmonella organisms on California dairies.     

Diversity of Salmonella serotypes in cull (market) dairy cows at slaughter.

OBJECTIVE: To determine the diversity of Salmonella serotypes isolated from a large population of cull (market) dairy cows at slaughter. DESIGN: Cross-sectional study. SAMPLE POPULATION: Salmonella organisms isolated from the cecal-colon contents of 5,087 market dairy cows. PROCEDURE: During winter and summer 1996, cecal-colon contents of cull dairy cows at slaughter were obtained from 5 US slaughter establishments. Specimens were subjected to microbiologic culturing for Salmonella spp at 1 laboratory. Identified isolates were compared with Salmonella isolation lists published by the Centers for Disease Control and Prevention (CDC) and the National Veterinary Services Laboratory (NVSL) for approximately the same period. The Simpson diversity index was used to calculate the likelihood that Salmonella isolates selected randomly by establishment were different. RESULTS: Of 58 Salmonella serotypes identified, Salmonella ser. Montevideo was the most prevalent. Two of the top 10 CDC serotypes identified from in 1996, Salmonella ser. Typhimurium and S Montevideo, appeared on our top 10 list; 8 of the top 10 were found on NVSL listings. Thirty-one of 59 S. Typhimurium isolates were identified as DT104 and found at a west slaughter establishment, 30 during the winter and 1 during the summer. The greatest diversity of serotypes was at a southeast establishment during the summer; the least diversity was at a central establishment in the winter. CONCLUSIONS AND CLINICAL RELEVANCE: 58 Salmonella serotypes were isolated from market dairy cows at slaughter and could pose a threat for food-borne illness. Salmonella Montevideo was the most frequently isolated serotype and may contribute substantially to salmonellosis in dairy cattle.     

Salmonella in California wildlife species: prevalence in rehabilitation centers and characterization of isolates.

Fecal samples from 212 selected marine mammals, marine birds, and raptors were cultured for Salmonella spp. on arrival at rehabilitation centers in California from May 1999 through July 2000. Salmonella spp. were cultured from nine (4%) animals, and seven serotypes were isolated: Johannesberg, Montevideo, Newport, Ohio, Saint Paul, Enteritidis Group D, and 4,5,12:1 Monophasic. One western gull (Larus occidentalis) had two serotypes. Antibiotic susceptibilities and chromosomal fingerprints were evaluated for Salmonella isolates. Some isolates were resistant to gentamicin, amoxicillin-clavulanic acid, and ampicillin. Chromosomal fingerprints with XbaI and XhoI restriction enzymes differed between serotypes but not between individuals carrying the same serotype of Salmonella.     

Distribution of Salmonella in swine herds in Québec.

Five porcine finishing units, previously identified as contaminated by Salmonella, were sampled to identify possible sources of contamination and to study the distribution of Salmonella within the herds. A total of 208 environmental samples were taken and 87 samples (42%) were found contaminated by Salmonella spp. Salmonella was recovered from several types of samples. Among these, fecal material from pens, building environment such as doors, floors, ventilation units, dust and farm accessories were most often found positive. Some of the flies and rodents were also positive. Two of the finishing units were part of an integrated production system and the prevalence and distribution of Salmonella spp. at different production steps of the integrated facilities were studied. Forty-one farms were sampled and a total of 1923 faecal samples in randomly selected pens were analysed. One hundred and fifty-one samples (7.9%) were positive for Salmonella spp. Among the farms sampled, 70.7% (29/41) were positive for isolation of Salmonella. The different levels in the integrated production were unevenly contaminated. Replacement sow (15.9%) and finishing unit for gilts (21.9%) were the most contaminated levels. Ten serotypes of Salmonella (n = 132) were identified in the production pyramid with a predominance of Salmonella Derby (37.1%) and Salmonella Typhimurium (34.1%). Pulse Field Gel Electrophoresis analysis of the various isolates from serotypes and Salmonella Typhimurium, Salmonella Derby and Salmonella Anatum showed no variation in the genetic profiles, within each serotype, suggesting a vertical contamination throughout the different production steps.     

Serovars of Salmonella isolated from Danish turkeys between 1995 and 2000 and their antimicrobial resistance

The prevalence of Salmonella serovars and their antimicrobial resistance patterns were investigated among Danish turkeys between 1995 and 2000, by sampling the flocks approximately 14 days before they were slaughtered. Within the flocks, the prevalence of salmonella varied from 7.1 per cent to 25 per cent, and 24 different serovars were detected. The five most prevalent, which accounted for 58.5 per cent of the isolates were Salmonella Heidelberg (16.2 per cent of the isolates), Salmonella Agona (15.8 per cent), Salmonella Derby (12.4 per cent), Salmonella Muenster (7.3 per cent) and Salmonella Anatum (6.8 per cent). In addition, a few rough isolates and isolates belonging to the antigenically incomplete formulae 6,7:-:- and 4,12:b:- were found. The level of antimicrobial resistance was low; the highest resistance was recorded to ampicillin (13.7 per cent) and streptomycin (9.0 per cent) followed by tetracycline (8.5 per cent), sulphonamides (7.7 per cent) and spectinomycin (4.7 per cent). Resistance to quinolones was very low: four isolates were resistant to nalidixic acid, and only one was resistant to enrofloxacin. No resistance was recorded to colistin, apramycin, ceftiofur, florfenicol, or amoxycillin with clavulanic acid. Only 24 isolates were resistant to two or more compounds in various combinations of up to six compounds; one Salmonella Havana isolate was resistant to six compounds. Six isolates were serovar Typhimurium, but none of them belonged to phage type DT104.     

Direct and indirect transmission of four Salmonella enterica serotypes in pigs

Background

Feed-borne spread of Salmonella spp. to pigs has been documented several times in recent years in Sweden. Experiences from the field suggest that feed-associated serotypes might be less transmittable and subsequently easier to eradicate from pig herds than other serotypes more commonly associated to pigs. Four Salmonella serotypes were selected for experimental studies in pigs in order to study transmissibility and compare possible differences between feed-assoociated (S Cubana and S Yoruba) and pig-associated serotypes (S Derby and S Typhimurium).

Methods

Direct contact transmission was studied in four groups of pigs formed by six 10-week-old salmonella negative pigs commingled with two fatteners excreting one of the four salmonella serotypes. Indirect transmission was studied by putting six 10-week-old salmonella negative pigs in each of four salmonella contaminated rooms. Each room had previously housed a group of pigs, excreting one of the four selected serotypes.All pigs were monitored for two weeks with respect to the faecal excretion of salmonella and the presence of serum antibodies. At the end of the trial, eight samples from inner tissues and organs were collected from each pig at necropsy.

Results

In the four direct transmission groups, one pig shed Salmonella (Cubana) at one occasion. At necropsy, S Typhimurium was isolated from one pig.In the indirect transmission groups, two pigs in the Yoruba room and one pig in each of the other rooms were excreting detectable levels of Salmonella once during the study period of two weeks. At necropsy, S Derby was isolated from one of six pigs in the Derby room and S Typhimurium was isolated from four of the six pigs in the Typhimurium room.No significant serological response could be detected in any of the 48 pigs.

Conclusions

These results show that all four selected serotypes were able to be transmitted in at least one of these field-like trials, but the transmission rate was low in all groups and no obvious differences between feed-associated and pig-associated serotypes in the transmission to naïve pigs and their subsequent faecal shedding were revealed. However, the post mortem results indicated a higher detection of S Typhimurium in the ileocecal lymph nodes of pigs introduced into a contaminated environment in comparison with the other three serotypes.     

Equine salmonellosis in southern Brazil

The Salmonella sp. genus is identified in several species, and the zoonosis it causes is one of the most important types worldwide. The specifics of salmonellosis vary according to the function of the serovar involved, the species affected, age and predisposing factors. However, few cases of equine salmonellosis have been reported. This study presents ten confirmed salmonellosis cases in equines in southern Brazil. Six were adult animals with stress factors preceding the disease, while four were foals, three of which presented with hyperacute manifestations. The main clinical signs were diarrhea, anorexia, and hyperthermia. Lesions varied in distribution and severity, although fibrinonecrotic or necrohemorrhagic enteritis was observed in all animals, mainly in the large intestine (large colon and cecum—8/10) and small intestine (3/10). Substantial liquid content, mainly hemorrhagic, was observed in all animals. The most characteristic microscopic lesion was mucosa necrosis, which is often accompanied by fibrin deposition, followed by necrosis of follicular centers and vascular changes. Bacterial isolation revealed seven isolates. Five were serotyped, and the serovars Typhimurium and Anatum were associated with two cases each, while Muenster was associated with a case whose lesion pattern varied. Immunohistochemical staining was positive in all cases. All diagnoses were based on the clinical history, macroscopic and histological lesions, and the bacterial isolation and/or immunostaining associated with histological lesions.     

Salmonella serotypes from animals in New York State, 1978-1983

The salmonella serotypes isolated during 1978 to 1983 at the diagnostic and clinical laboratories of the New York State College of Veterinary Medicine from animal sources in New York state were reviewed and compared to earlier data from New York state animals and to national data for both human and animal sources. A total of 255 salmonella strains were studied from the six year period and included 33 serotypes. Salmonella enteritidis ser Typhimurium continued to be the most commonly reported serotype followed by serotype Anatum. Generally serotypes from New York state animals reflected national data on salmonella serotypes with a few exceptions. Serotype Dublin continued to be absent from New York animal populations. Bovine and equine species were the most common salmonella sources.     

The prevalence and antimicrobial susceptibilities of Salmonella and Campylobacter in ducks in Taiwan

Cloacal swabs were sampled from 100 duck farms in Taiwan between March 2000 and January 2001 for isolation and standard cultivation of Salmonella spp. and thermophilic Campylobacter spp. Salmonella spp. were isolated from 4.6% (91/2000) of ducks from 20% (20/100) of duck farms. Ten serotypes of Salmonella enterica were identified: S. Potsdam (31.9% of isolates), S. Dusseldorf (18.7%), S. Indiana (14.3%), S. Typhimurium (7.7%), S. Hadar (5.5%), S. Newport (4.4%), S. Derby (4.4%), S. Montevideo (2.2%), S. Schwarzengrund (2.2%), and S. Asinnine (1.1%). Isolation of S. Asinnine or S. Indiana from poultry had not hitherto been described in Taiwan. The salmonella isolation rate in ducklings under two weeks of age was significantly higher than the other age groups (P<0.05). Campylobacter spp. were isolated from 43.5% (1045/2400) of ducks from 92% (92/100) of duck farms. Among them, 991 isolates (94.8%) were identified as C. jejuni and 54 isolates (5.2%) as C. coli. The campylobacter isolation rate in ducklings under two weeks of age was significantly lower than other age groups (P<0.05). Antimicrobial susceptibility testing was conducted by the disk diffusion and E- test methods. The results indicated that Salmonella isolates were 100% susceptible to amikacin, amoxicillin/clavulanic acid, ceftraxone, cephalothin, ciprofloxacin, norfloxacin, ofloxacin, and polymyxin B. A markedly higher antimicrobial resistance to amoxicillin, florfenicol, flumequine, josamicin/trimethoprim, nalidixic acid, nitrofurantoin, norfloxacin, ofloxacin, polymyxin B, sulfamethoxazole/trimethoprim and tetracycline was found in campylobacter isolates.     

Salmonella Muenster infection in a dairy herd

The overall purpose of this study was to provide information on animal and occupational health associated with the infection of a diary herd with Salmonella Muenster that would be useful in the management of dairy herds so infected. This retrospective, longitudinal report records a 2-year infection of a 140-cow dairy herd with S. Muenster, which was likely introduced by additions to the herd. Six cows aborted or had diarrhea due to salmonellosis in the last trimester of pregnancy. Additions to the herd and the presence of animals that had not received an Escherichia coli bacterin-toxoid were risk factors for salmonellosis. One neonate died, and 24 of 36 calves born between November 1998 and May 1999 had diarrhea by 1 mo of age. Initially, over 60% of the cows were fecal positive; within 6 months, all cows but I had become infected. The intermittent shedding of the organism and the eventual zero prevalence highlight the inappropriateness of extensive culling as an eradication strategy. Cultures of the bulk-tank milk filters were more sensitive than cultures of the bulk-tank milk samples at detecting S. Muenster. Two months after the index case, S. Muenster was cultured from the milk of 7.8% of the cows. Positive fecal or milk cultures were not associated with impaired health or production. The herd's milk was a zoonotic risk, but contact with infected animals was not. The organism spread easily between operations, likely via manure-contaminated clothing and footwear.     

Presence of arsenic resistance in Salmonella enterica serovar Kentucky and other serovars isolated from poultry

A collection of 125 Salmonella enterica poultry isolates (71 serovar Kentucky isolates, and the remainder belonging to serovars Alachua, Enteritidis, Hadar, Heidelberg, Montevideo, Mbandaka, Senftenberg, Typhimurium, and Worthington) were tested for the ability to grow on tryptic soy agar containing sodium arsenite [As(III)] or arsenate [As(V)]. All serovar Kentucky isolates and 18 of the non-Kentucky isolates were able to grow in the presence of 0.1 mM As(III), and 69 grew in the presence of 1 mM As(V). Thirty of the non-Kentucky isolates did not grow at these As(III) and As(V) concentrations, but seven grew at 1 mM As(III) and 10 mM As(V). PCR-based analysis demonstrated the presence of arsB and arsD sequences in all Kentucky isolates, whereas one or both of these sequences were present in only 30 of the other isolates. It remains to be determined if these arsenic-resistance determinants benefit Salmonella exposed to man-made arsenic-containing compounds in poultry environments.     

A temporal study of Salmonella serovars from environmental samples from poultry breeder flocks in Ontario between 1998 and 2008

A temporal study was carried out to determine Salmonella prevalence, trends, major serovars, and their clusters from environmental samples, in poultry breeder flocks in Ontario between January 1998 and December 2008. Surveillance data were obtained from the Ontario Hatchery and Supply Flock Policy. Logistic regression with a random effect for flock was used to identify factors [poultry type, year (trend) and season] associated with the prevalence of Salmonella. A cluster detection test was used to identify clusters of common serovars. The period prevalence of Salmonella was 47.4% in broiler-breeder, 25.7% in layer-breeder, and 19.6% in turkey-breeder flocks. The overall trend in the prevalence of Salmonella was decreasing for all breeder types, due primarily to decreasing trends of Salmonella Heidelberg. The seasonal effects varied by year with the highest probability of Salmonella occurring in different seasons. The 4 most common serovars identified were Salmonella Heidelberg, Kentucky, Hadar, and Typhimurium in broiler-breeders; Salmonella Heidelberg, Brandenburg, Thompson, and Typhimurium in layer-breeders; and Salmonella Heidelberg, Saintpaul, Brandenburg, and Muenster in turkey-breeders. Salmonella Enteritidis was infrequently isolated in all poultry breeder types. Temporal clusters of different serovars were identified in all poultry breeder types. Clusters of Salmonella Heidelberg, Typhimurium, and Hadar from environmental samples from breeder flocks were detected during a similar period to clusters from hatchery fluff samples from the same population. Therefore, interventions at the breeder flock-level might help to reduce transmission of Salmonella from breeder flocks to hatcheries and possibly, to lower levels of the poultry production chain.     

Prevalence of Salmonella serotypes on pig carcasses from high- and low-risk herds slaughtered in three abattoirs

The aim of this study was to compare the prevalence of Salmonella serotypes at two different sites on pig carcasses from herds classified as high-risk or low-risk and to elucidate the relationship between carcass contamination levels and serological status. Caecal samples and carcass surface swabs were cultured for Salmonella from a total of 210 pigs from low risk herds (< 19% of pigs in herd Salmonella seropositive) and 209 pigs from high risk herds (> 32% of pigs in herd Salmonella seropositive) in three abattoirs. Meat juice samples were collected for analysis by ELISA. The prevalence of Salmonella in the caecal contents of "low-risk" pigs was 10%, which was significantly lower than the 19% prevalence in "high-risk" pigs (p < 0.01). The corresponding figures for skin samples collected immediately post-evisceration were 2% and 12%. The predominant Salmonella serotype in the caecal contents of both the low-risk and high-risk pigs was Salmonella Typhimurium. Salmonella Kentucky and Salmonella Derby were the most frequent isolates from the carcass surface swabs of low- and high-risk pigs respectively. There was a positive association between seropositivity of pigs from high-risk herds and caecal carriage (p < 0.05). Results showed that herd categorisation based on serological results was useful in predicting Salmonella isolation rates from caecal samples and surface swabs of slaughtered pigs.     

Prevalence and antimicrobial resistance of Salmonella spp. in pet mammals, reptiles, fish aquarium water, and birds in Trinidad

The prevalence of Salmonella spp. was determined in 970 animals comprising 423 pet birds, 485 fish aquaria water and 62 other pets (40 pet mammals, 14 reptiles, eight others - crustaceans, snail, stingray) from both pet shops and households throughout Trinidad. The serotypes of Salmonella spp. isolated were identified and the resistance to various antimicrobial agents was determined. Overall nine (0.9%) of 970 pet animals were positive for Salmonella spp. Six isolates of Salmonella spp. were recovered from all pet birds with two isolates of serotype Aberdeen and one isolate each of Thompson, Rubislaw, Panama and Newport. The prevalence of Salmonella spp. in birds was 0.9%. Four isolates of Salmonella spp. were recovered from fish aquaria water, serotypes included Panama (two isolates), Newport (one isolate) and Virchow (one isolate). Prevalence of Salmonella spp. from fish aquaria was 0.4%. No isolate of Salmonella spp. was detected in pet mammals sampled while two isolates were recovered from reptiles, S. Enteritidis and S. Montevideo. One isolate of Salmonella spp. was recovered from a stingray, serotype unknown. Antimicrobial resistance was present is all animal types. The highest prevalence of resistance was to streptomycin among isolates from birds (83.3%) and other pets (100.0%) while isolates from fish aquarium water exhibited comparatively high resistance to cephalothin (50.0%). It was concluded that the isolation of Salmonella spp. from apparently healthy birds, fish aquarium water and other pet animals may pose a health risk to their owners and contacts as all serotypes are known to be potentially pathogenic depending on the oral dosage of the organism and the immune status of those in contact. The high prevalence of resistance to antimicrobial agents among Salmonella isolates across pet species may pose chemotherapeutic consequences to their owners and contacts.     

Salmonella in meats,water, fruit and vegetables as disclosed from testing undertaken by Food Business Operators in Ireland from 2005 to 2009

Abstract

Food Business Operators (FBO) are responsible for the safety of the food they produce and in Ireland those under the regulatory control of the Department of Agriculture, Food and Marine are required to provide summary data on microbiological tests undertaken as part of their food safety controls. These data are provided to the National Reference Laboratory through the 25 private laboratories undertaking the testing.

Results

Over the five-year period Salmonella sp. was isolated from 0.7% of the 254,000 raw meat or raw meat products tested with the annual prevalence ranging from 0.5 to 1.1%. Poultry meats were consistently more contaminated than other meats with higher recovery rates in turkey (3.3%), duck (3.3%), and chicken (2.5%) compared with meats of porcine (1.6%), ovine (0.2%) and bovine origin (0.1%). Salmonella sp. was also isolated from 58 (0.06%) of the 96,115 cooked or partially cooked meat and meat products tested during the reporting period with the annual percentage positive samples ranging from 0.01 to 0.16%. A total of 50 different serotypes were recovered from raw meats over this period with the greatest diversity found in poultry samples (n = 36). Four serotypes, Kentucky, Typhimurium, Agona and Derby accounted for over 70% of all isolates detected on FBO testing over the period 2005 to 2009.

Conclusions

Capturing microbiological data generated by Food Business Operators allows the regulatory sector access to a substantial amount of valuable data with the minimum financial outlay.     

新疆北疆地区致犊牛腹泻大肠杆菌的分离鉴定及部分生物学特性

为研究确定新疆北疆地区规模化奶牛场犊牛腹泻病原性大肠杆菌的优势血清型、致病性及毒力因子特征。采用细菌学、免疫学及分子生物学的方法对从新疆呼图壁、石河子、奎屯3个主要奶牛生产基地14个规模化奶牛场10日龄内腹泻犊牛直肠棉拭子样品进行了大肠杆菌的分离与鉴定、O血清群、黏附素及肠毒素的测定。结果从302份样品中分离并经生化鉴定获得180株呈β溶血的大肠埃希菌,其中94株对小鼠有致病性;对其中53株代表菌株的O血清型、黏附素及肠毒素测定,结果为8株携带K99菌毛及STa毒素基因,6株携带F41茵毛基因,6株产生LT毒素;28株分离株分布于16个O血清型,其中O101,O6,O114,O78为优势血清型,占被测菌株的50％。结果表明,新疆北疆主要奶牛养殖区致犊牛腹泻大肠杆菌是以携带K99、F41和产ST的溶血性大肠杆菌为主,其研究结果为犊牛大肠杆菌性腹泻的免疫防治提供病原学依据。     

Detection of Salmonella in Finishing Pigs on Farm and at Slaughter in Piedmont,Italy

Salmonella is one of the most common causes of human gastroenteritis often associated with pork consumption. The aims of this cross‐sectional study were to collect preliminary data on the presence of Salmonella enterica in pigs in Piedmont (Italy), through sampling on farm and at slaughter and to gather pilot data on serotypes and phagetypes present in the sampled area and distribution of anti‐microbial resistance among isolated strains. Salmonella was detected through culture and identified with Salmonella spp. and Salmonella Typhimurium PCR; positive samples were serotyped, phagetyped and tested for antibiotic susceptibility. Positive samples (from 9% of faeces up to 29% of tonsils) were found in 64% of the herds. Salmonella spp. was retrieved also from scalding water. Most of the isolates were Salmonella Derby, Salmonella Typhimurium and Salmonella 4,5,12:i:‐. The results of Salmonella Typhimurium specific PCR suggested that Salmonella 4,5,12:i:‐ might be unrecognized by serotyping. Anti‐microbial resistance was recorded in 75–100% of the isolates. Phagetyping allowed the identification of DT104B and DT46A strains. These results set the bases for further research studies that would aim to estimate the real herd prevalence in Piedmont and the diffusion of serotypes and anti‐microbial resistant strains within the same region.