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.     

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.     

Salmonella infections in neonatal dairy calves.

To estimate herd prevalence of Salmonella spp, fecal specimens were obtained for culture from neonatal calves of 47 Ohio dairy herds. Of the 452 calves tested, 10 calves from 7 farms were culture-positive. Salmonella serotypes isolated were S dublin, S typhimurium, S enteritidis, S agona, S mbandaka, and S montevideo. Bulk tank milk filters from these dairies were also submitted for culture. Salmonella sp was isolated from 1 of the 50 filters, and 2 calves from this herd were found to be shedding Salmonella sp of the same serotype.     

Salmonella and on-farm risk factors in healthy slaughter-age cattle and sheep in eastern Australia

OBJECTIVE: To examine healthy slaughter-age cattle and sheep on-farm for the excretion of Salmonella serovars in faeces and to identify possible risk factors using a questionnaire. PROCEDURE: The study involved 215 herds and flocks in the four eastern states of Australia, 56 with prior history of salmonellosis. Production systems examined included pasture beef cattle, feedlot beef cattle, dairy cattle, prime lambs and mutton sheep and animals were all at slaughter age. From each herd or flock, 25 animals were sampled and the samples pooled for Salmonella culture. All Salmonella isolated were serotyped and any Salmonella Typhimurium isolates were phage typed. Questionnaires on each production system, prepared in Epi Info 6.04, were designed to identify risk factors associated with Salmonella spp excretion, with separate questionnaires designed for each production system. RESULTS: Salmonellae were identified in all production systems and were more commonly isolated from dairies and beef feedlots than other systems. Statistical analysis revealed that dairy cattle were significantly more likely to shed Salmonella in faeces than pasture beef cattle, mutton sheep and prime lambs (P<0.05). A wide diversity of Salmonella serovars, all of which have been isolated from humans in Australia, was identified in both cattle and sheep. Analysis of the questionnaires showed access to new arrivals was a significant risk factor for Salmonella excretion on dairy properties. For beef feedlots, the presence of large numbers of flies in the feedlot pens or around stored manure were significant risk factors for Salmonella excretion. CONCLUSION: Dairy cattle pose the highest risk of all the slaughter-age animals tested. Some of the identified risk factors can be overcome by improved management practices, especially in relation to hygiene.     

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.     

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.     

Sources of Prototheca spp in a dairy herd environment

A source of Prototheca spp causing mastitis in a herd of 263 milking cows in North Carolina was investigated. Of 38 samples from the dairy environment, 18 (47%) contained Prototheca spp. Isolation sites included cattle drinking water; a feed trough; mud, dirt, and excreted feces from a dirt lounging area; water, sludge, mud, and vegetation from a creek in the lounging area; and the floor of a freestall barn. Samples were collected from 5 additional dairies, including one dairy with and 4 dairies without a history of protothecal mastitis. Prototheca spp were isolated from 48 (25%) of 190 samples from various sites on all 6 dairies. Isolates were P zopfii (45; 94%) and P wickerhamii (3; 6%). Isolation frequency ranged from 4 to 47% of samples/dairy. There was no apparent difference in the isolation frequency of Prototheca spp from samples from dairies with or without a history of protothecal mastitis. Sites characterized by wetness and the presence of organic matter most commonly yielded Prototheca spp. Because Prototheca spp appear to be common in the dairy environment, factors in addition to presence in the environment may be important in development of protothecal mastitis.     

Osteomyelitis associated with Salmonella enterica SS arizonae in a colony of ridgenose rattlesnakes (Crotalus willardi).

The identification of three Arizona ridgenose rattlesnakes (Crotalus willardi) with Salmonella arizonae-associated osteomyelitis led to a 5-yr prospective study of radiographic signs and Salmonella intestinal carriage rates in a 19-member colony of this rattlesnake species. Ventrodorsal radiographs were performed and cloacal swabs were cultured for Salmonella spp. annually. Ten snakes survived the 5-yr period, with six of them remaining free of bony lesions. Three snakes that had no bony lesions in 1995 developed radiographic signs of osteomyelitis during the study. Six snakes with bony lesions at the beginning of the study died or were euthanatized due to osteomyelitis during the study. The radiographic signs of osteomyelitis were progressive for five snakes that were serially radiographed. Only one snake with radiographic signs of osteomyelitis at the beginning of the study was still alive at the end of the study, and this animal's bony lesions were more extensive at the end. Thirty-nine intestinal S. arizonae isolates, representing 13 serotypes, were obtained from the 19 snakes. Salmonella arizonae serotype 56:Z4,Z23 was isolated only once from a cloacal culture, from a snake that had no radiographic bone lesions. Twelve extraintestinal Salmonella isolates, representing two serotypes, were isolated from six snakes. All extraintestinal isolates except one were of S. arizonae serotype 56:Z4,Z23, and all isolates from bone were of this serotype. One snake with characteristic bone lesions died, and Providencia rettgeri was cultured from each of the tissues cultured, whereas no Salmonella spp. were isolated from this snake. Salmonella arizonae serotype 56:Z4,Z23 [corrected] appears to have a tropism for bone and other extraintestinal sites in C. willardi and may cause a progressive, ultimately fatal disease in this species.     

Detection of Salmonella organisms and assessment of a protocol for removal of contamination in horse stalls at a veterinary teaching hospital

OBJECTIVES: To assess methods of detecting environmental contamination with Salmonella organisms and evaluate a cleaning and disinfection protocol for horse stalls in a veterinary teaching hospital. DESIGN: Original study. SAMPLE POPULATION: 37 horses with diarrhea likely to be caused by Salmonella infection and their stall environments. PROCEDURES: Fecal samples were collected from horses daily during hospitalization; samples were obtained from stall sites after cleaning and application of disinfectants. Fecal and environmental samples were cultured for Salmonella spp and tested via polymerase chain reaction (PCR) assay to detect Salmonella DNA. RESULTS: 1 horse died and 2 were discharged prior to sample collection. Fecal samples from 9 of 34 horses yielded growth of Salmonella organisms on bacteriologic culture, and 23 yielded positive results via PCR assay on > or = 1 occasion. Among environmental samples from 21 stalls, salmonellae were detected at > or = 1 stall site on 6 of 78 occasions, and > or = 1 stall site yielded positive results via PCR assay on 69 of 77 occasions. Salmonella DNA was detected more frequently in samples of stall drains, cracks, and corners. Salmonella spp were cultured from samples of 3 stalls after both initial and second cleaning and disinfection cycles, but no organisms were detected in samples obtained after use of a peroxygen disinfectant. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that stalls in which horses with salmonellosis were housed should only be used to accommodate newly hospitalized horses after samples (collected after 2 cycles of cleaning and disinfection) from drains, cracks, and corners yield negative results on bacteriologic culture.     

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.     

Prevalence of Salmonella spp. in pet reptiles in Japan

From November 2000 to July 2002, 112 fecal samples from pet reptiles, including 18 turtles, 71 lizards and 23 snakes, sold at a pet shop were examined for the prevalence of Salmonella spp. in Japan. Salmonella spp. were isolated from 83 (74.1%) of 112 samples, and a total of 112 Salmonella isolates were identified as subspecies I to IV. The majority of isolates (62.5%) belonged to subspecies I and 54 isolates could be identified as any of 28 serovars. The predominant serovars were found to be S. Bardo, S. Newport and S. Panama, which cause human salmonellosis. These results indicate that pet reptiles may be a potential infectious source of human salmonellosis in Japan.     

Comparative plasmid profile analysis of Salmonella typhimurium var. Copenhagen strains from a Salmonella outbreak in hospitalized horses]

From April 1990 through June 1991 clinical salmonellosis and asymptomatic faecal excretion of Salmonella spp. were seen in hospitalized horses at two veterinary hospitals. 76 Salmonella strains from hospitalized horses and 18 strains from horses without any clinical contact were characterized by serotyping and plasmid profile analysis. From April 1990 through January 1991 97.8% of the hospitalized horses were infected with strains of S. typhimurium var. Copenhagen, which were closely related according to their similar plasmid patterns. Other strains of S. typhimurium var. Copenhagen and serotype S. enteritidis were isolated not before February 1991. In the same period various plasmid profile types of S. typhimurium var. Copenhagen and strains of S. typhimurium, S. enteritidis and S. lexington were isolated from horses of the control group. Our results suggest that the high incidence of salmonellosis and latent salmonella infection in hospitalized horses was mainly due to the spread of one particular strain of S. typhimurium var. Copenhagen and that this strain was obviously acquired during hospitalisation.     

Prevalence of fecal shedding of Salmonella spp in dairy herds

OBJECTIVE: To estimate prevalence of Salmonella spp in Ohio dairy farms and to identify potential risk factors for fecal shedding of salmonellae. DESIGN: Cross-sectional study. SAMPLE POPULATION: 105 Ohio dairy farms. PROCEDURE: Individual fecal samples from all mature cows in study herds were tested for Salmonella spp by use of standard bacteriologic culture procedures. Herds were identified as infected if at least 1 cow was shedding Salmonella spp. Information regarding herd characteristics, management practices, and health history were collected. Potential risk factors for herd-level Salmonella infection were identified. RESULTS: In 31% of the study herds (95% confidence interval, 22 to 40%), at least 1 cow was shedding Salmonella spp. Six percent of 7,776 fecal samples contained Salmonella organisms; prevalence within infected herds ranged from < 1 to 97%. Herd size, use of free stalls for lactating and nonlactating cows, and use of straw bedding in nonlactating cows were significantly associated with fecal shedding of Salmonella spp, as determined by use of univariate analysis. By use of multivariate analysis, large herds were more likely to be infected than smaller herds; however, no other factors were associated with Salmonella infection after adjustment for herd size. CONCLUSIONS AND CLINICAL RELEVANCE: Subclinical shedding of Salmonella spp is common in Ohio dairy herds, although we could not identify specific interventions that may influence the prevalence of Salmonella spp on dairy farms. It appears that large herd size and intensive management may provide an environment conducive to Salmonella shedding and chronic dairy herd infection.     

Detection of Salmonella spp. in stray dogs in Bursa Province, Turkey: first isolation of Salmonella Corvallis from dogs

The prevalence and antimicrobial sensitivity of Salmonella spp. in stray dogs in Bursa province, Turkey were determined from a total of 82 faecal samples by bacteriological methods. Of the dogs, nine (11%) were positive for salmonellae-carrying. All Salmonella isolates were serotyped as S. Corvallis, and were sensitive to amoxycillin/clavulanic acid, ampicillin, cephalothin, chloramphenicol, enrofloxacin, gentamicin, kanamycin, nalidixic acid, neomycin, oxytetracycline and trimethoprim/sulphamethoxazole, while 66.7% of them were resistant to streptomycin. It was concluded that stray dogs could be an important carrier of salmonellae as well as a source of human salmonellosis in Turkey. Additional studies are needed to clarify the epidemiological relationship between S. Corvallis isolated from dogs and humans with regard to public health. This is the first report on the isolation of S. Corvallis from dogs in the country.     

Antibiotic Resistance in Salmonella Isolated from Tegus (Tupinambis spp.)

In recent years, an increase in human clinical cases of reptile-associated salmonellosis has been identified, and it has been attributed to the increased popularity of these animals as pets. Limited information is available regarding the distribution of Salmonella spp. serotypes in different reptile species and the antimicrobial resistance patterns of Salmonella spp. isolated from pet reptiles. This article describes the prevalence of Salmonella spp., distribution of serotypes, and antibiotic susceptibility patterns from isolates cultured from cloacal swabs obtained from 14 tegu lizards (Tupinambis spp.). Eighteen strains of Salmonella belonging to different serotypes were obtained from the 14 tegu lizards. Of the 18 Salmonella spp. isolates, 8 (44.4%) were from Salmonella subspecies I, with a majority of isolates belonging to the Eastbourne serotype (3 strains), Nottingham serotype (2 strains), and Brancaster serotype (2 strains), and only 1 belonging to the Apapa serotype. Less common serotypes were detected in 5 isolates, including 2 each belonging to Salmonella subspecies II and IIIb, respectively, and 1 to Salmonella subspecies IIIa. The serotype of 5 other Salmonella isolates could not be determined. All 18 isolates were resistant to at least 6 of the antimicrobial drugs tested. These results confirm the potential zoonotic risk from handling reptiles, suggesting that measures to educate the reptile-owning public are necessary.     

Comparison of phenotypic traits and genetic relatedness of Salmonella enterica subspecies arizonae isolates from a colony of ridgenose rattlesnakes with osteomyelitis.

Reptiles are well-known sources of human Salmonella infections; however, little is known about the ability of Salmonella to cause disease in reptiles. Thirty-seven isolates of Salmonella enterica subspecies arizonae (S. arizonae) were obtained from retrospective and prospective studies of a closed colony of ridgenose rattlesnakes (Crotalus willardi) with osteomyelitis. All isolates (N = 7) from bone lesions were of a single serotype, 56:z4,z23, and this serotype was found on only 1 occasion among 8 other serotypes isolated from 21 cloacal and intestinal samples. The remainder (N = 7) of serotype 56:z4,z23 isolates were from other extraintestinal sites, including liver, ovary, blood, and testis. S. arizonae isolates were susceptible to most antimicrobials, and plasmid profiles did not correlate with serotype or antimicrobial resistance. Isolates of the 56:z4,z23 serotype (N = 14) formed a tight cluster with 95% similarity by XbaI macrorestriction analysis. Individual isolates of serotypes, 56:z4,z23, 38:(k)-z35, and 48:i-z invaded HeLa cells but an isolate of serotype 50:r-z did not. The same individual isolates of serotype 56:z4,z23 and 48:i-z also invaded viper heart cells. The Salmonella InvA gene was detected by polymerase chain reaction (PCR) in all S. arizonae serotypes tested, including 5 serotype 56:z4,z23 isolates and individual isolates of serotypes 48:i-z and 50:r-z. A source or possible explanation for increased virulence of S. arizonae serotype 56:z4,z23 in this unique host has not been found.     

The prevalence, incidence, geographical distribution, antimicrobial sensitivity patterns and plasmid profiles of milk filter Salmonella isolates from Ontario dairy farms.

The prevalence, incidence and geographical distribution of Salmonella on dairy farms in southwestern Ontario were determined by culturing bulk milk filters from 511 randomly selected dairy farms. Milk filters from 22 farms (2.9%) were Salmonella-positive, with a cumulative incidence rate of 9.0% per year. Positive farms were distributed throughout southwestern Ontario, but were regionally clustered. The serotype, biotype, antimicrobial sensitivity pattern and plasmid profile of the Salmonella isolates from six farms where Salmonella were recovered on two occasions were identical. All of the Salmonella strains isolated were sensitive to commonly used antimicrobials.     

Antimicrobial resistance in Salmonella enterica subspecies enterica serovar Dublin from dairy source calves in the central San Joaquin Valley, California (1998-2002)

The present study describes antimicrobial resistance patterns of Salmonella enterica subspecies enterica serovar Dublin (S. Dublin) in clinical submissions from calves and temporal and farm-type trends in antimicrobial resistance patterns of the isolates. A total of 300 isolates of S. Dublin were obtained from fecal or internal organs of calves fewer than 120 days of age originating from 84 dairies and 18 calf ranches from July 1998 to December 2002. The isolates were susceptibility tested to a panel of 10 antimicrobials using the disk diffusion assay. Temporal and farm-type trends in individual antimicrobial inhibition zone sizes were assessed and antimicrobial resistance patterns were described using cluster analysis. Isolates obtained from calf ranches compared with dairies exhibited decreased susceptibility to florfenicol, gentamicin, neomycin, sulfisoxazole, sulfamethoxazole/trimethoprim, and tetracycline. During the years 1998-2002, decreasing susceptibility was seen for ceftiofur, enrofloxacin, and sulfamethoxazole/trimethoprim. There were 20 different antimicrobial resistance patterns in the isolate set, indicating that S. Dublin has the ability to transfer and pick up resistance genes with relative ease. The trends seen in antimicrobial resistance in S. Dublin may likely be linked to antimicrobial drug use in young calves.