Salmonellosis associated with S typhimurium DT104 in the USA.
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Animals↗
Biomedical subjects
J M Gay
Publications and source records attributed to J M Gay.
Commingled grazing as a risk factor for trichomonosis in beef herds.
OBJECTIVE: To evaluate commingled grazing on public lands as a risk factor for Tritrichomonas foetus infection in beef herd bulls. DESIGN: Case-control study. SAMPLE POPULATION: Based on 1994 data from the mandatory Idaho bull testing program, all 65 infected herds (case herds), 78 randomly selected test-negative herds that tested < 10 nonvirgin bulls, and 81 randomly selected test-negative herds that tested > or = 10 nonvirgin bulls (control herds). PROCEDURE: Managers of government-owned grazing lands in Idaho identified producers who had grazing permits for an allotment under their jurisdiction in 1993 and for that allotment recorded the number of animals the producer was permitted to graze on the allotment, the number of herds with grazing permits, the total number of animals permitted, and the dates on which grazing began and ended. The number of bulls tested, number of times tested, and test results were collated from the testing database. RESULTS: The relative sensitivity of bacterial culture of preputial smegma was 81%. The attributable fraction of T foetus infection associated with commingled grazing was 33%, and the odds ratio of infection was 9.0 for herds commingled with > or = 14 other herds. The total number of animals permitted on an allotment, the use of public lands, and type of public lands used were not significantly associated with infection status. CLINICAL IMPLICATIONS: These results suggest that to control the spread of trichomonosis, the number of herds commingling on a grazing allotment should be minimized and commingled herds should be managed collectively.
Animal Husbandry↗
Veterinary involvement in management practices of beef cow-calf producers.
Management practices of 53 beef cow-calf producers were surveyed by use of a mail questionnaire. Producers were randomly selected from those who employ veterinarians to perform herd pregnancy examinations. Questions were asked about animal management, grazing and feeding, vaccination, and record-keeping practices. Median herd size was 250 breeding cows, and 2,329 of 2,491 (93%) randomly sampled cows in these herds were pregnant. Less than half of producers associated with these herds reported adoption of many beneficial practices related to bull management, infectious disease management, nutrition, and individual-animal record keeping, suggesting that a considerable number of producers are missing opportunities to optimize production and, thus, economic return. Use of individual-animal production records, which would enable more objective decision making on the basis of production and economic data, was not widespread. These findings suggested that veterinarians serving beef ranches have opportunities to provide additional services incorporating these management practices.
Animal Husbandry↗
Environmental reservoirs for Serratia marcescens intramammary infections in dairy cows.
Via special media, Serratia marcescens isolates were found in 3 bedding pack samples and in 2 milking parlor floor samples, and in milk samples from 19 cows during an episode of mastitis in a dairy cow herd. Chromosomal digest patterns of isolated S marcescens were indistinguishable for 18 of the milk samples and all bedding pack samples. Our findings provide strong evidence that the bedding pack was the reservoir of S marcescens associated with the outbreak of intramammary infections. Additionally, our ability to match digest patterns of isolates in the bedding pack and milk confirms the theory that S marcescens is an environmental pathogen capable of causing mastitis.
Animals↗
Transepidermal water loss of bovine teats.
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Animals↗
Serological diagnosis of bovine neosporosis by Neospora caninum monoclonal antibody-based competitive inhibition enzyme-linked immunosorbent assay.
Neospora caninum, a protozoan parasite closely related to Toxoplasma gondii, causes abortion and congenital infection in cattle. To investigate specific methods of antemortem diagnosis, the antibody responses of infected cows were evaluated by immunoblot assay and competitive inhibition enzyme-linked immunosorbent assay (CI-ELISA) by using a monoclonal antibody (MAb), MAb 4A4-2, against N. caninum tachyzoites. MAb 4A4-2 bound diffusely to the exterior surface of N. caninum tachyzoites and recognized a single 65-kDa band in immunoblots. MAb 4A4-2 was unreactive to antigens of two closely related apicomplexan protozoa, Toxoplasma gondii and Sarcocystis cruzi. Binding of MAb 4A4-2 was inhibited by mild periodate treatment of N. caninum antigen, demonstrating the carbohydrate nature of the epitope. Immunoblot analysis of N. caninum tachyzoite antigens with sera from cows with confirmed Neospora-induced abortion revealed at minimum 14 major antigens ranging from 11 to 175 kDa. Although the recognized antigens varied from cow to cow, antigens of 116, 65, and 25 kDa were detected in all cows with abortion confirmed to be caused by N. caninum. The binding of MAb 4A4-2 to N. caninum tachyzoite antigen was consistently inhibited by sera from Neospora-infected cows in a CI-ELISA format and was not inhibited by sera from Neospora antibody-negative cows. Furthermore, sera from cattle experimentally infected with T. gondii, S. cruzi, Sarcocystis hominis, or Sarcocystis hirsuta, which had cross-reactive antibodies recognizing multiple N. caninum antigens by immunoblot assay, did not inhibit binding of MAb 4A4-2 in the CI-ELISA. Thus, MAb 4A4-2 binds a carbohydrate epitope on a single N. caninum tachyzoite surface antigen that is recognized consistently and specifically by Neospora-infected cattle.
Abortion, Veterinary↗
Serologic responses of cattle and other animals infected with Neospora caninum.
OBJECTIVE: To examine cross-reactivity among Neospora caninum and closely-related apicomplexans. DESIGN: Sera from animals were examined for antibody production to N caninum and cross-reactivity to Toxoplasma gondii. ANIMALS: Cattle were experimentally infected with 3 tissue cyst-forming protozoan parasites N caninum, T gondii, and Sarcocystis sp, and calves were monospecifically inoculated with the intestinal coccidia, Eimeria bovis and Cryptosporidium parvum. Similar studies were done in laboratory rabbits inoculated with N caninum, T gondii, Hammondia hammondi, and Sarcocystis sp. Additionally, sera were obtained from ewes, lambs, goats, sows, cats, rats, and mice inoculated with N caninum tachyzoites. PROCEDURE: The indirect fluorescent antibody (IFA) and ELISA antibody tests (cattle only) were used to examine reactivity to N caninum; the modified direct agglutination, Sabin-Feldman dye, and IFA tests were used to evaluate reactivity to T gondii. RESULTS: Serologic cross-reactivity among N caninum, T gondii, and Sarcocystis sp was none or minimal by the IFA test. There was some reactivity to N caninum by the use of ELISA in cattle inoculated with Sarcocystis sp. CONCLUSIONS: The IFA test for N caninum was specific for the diagnosis of neosporosis in animals.
Animals↗
Prevalence of coagulase-positive staphylococci, other than Staphylococcus aureus, in bovine mastitis.
OBJECTIVE: To determine prevalence and relevance of coagulase-positive Staphylococcus hyicus and S intermedius intramammary infections (IMI) in dairy cows and determine the ability of the 4-hour tube coagulase (TC) test to differentiate the coagulase-positive staphylococci (CPS). DESIGN: Prevalence of CPS was determined for primiparous cows (point prevalence and prevalence at first parturition) and multiparous cows (point prevalence) of 2 herd groups: < 6% CPS IMI prevalence = low prevalence (LP); > 10% CPS IMI prevalence = high prevalence (HP). SAMPLE POPULATION: For prevalence, cows of 22 dairy herds. For TC, 1,038 CPS strains isolated from cow milk. PROCEDURE: Speciation of CPS from aseptically collected composite milk samples was performed. Coagulase-positive isolates from 4 cow groups were tested for their ability to coagulate rabbit plasma by 4 hours: LP and HP primiparous cows at parturition, and LP and HP cows any time after first parturition. RESULTS: Of 487 CPS in the prevalence study, 82.1% were S aureus, 17.7% were coagulase-positive S hyicus, and 0.2% were S intermedius. Of all CPS IMI in LP herds, 34% were coagulase-positive S hyicus; of all CPS IMI in HP herds, 9% were coagulase-positive S hyicus. Coagulase-positive S hyicus appeared to persist to the end of lactation in 4 cows (mean linear somatic cell count = 3.7). The TC test was > or = 97% sensitive, < or = 33% specific, and had a predictive value positive range of 60 to 97% for S aureus isolates. CONCLUSION: Coagulase-positive S hyicus appears capable of inducing chronic, low-grade IMI. Staphylococcus intermedius does not appear to be an important mastitis pathogen. The TC test is not valid to use as the sole method to differentiate CPS species.
Animals↗
Sensitivity of bacteriologic culture for detection of Escherichia coli O157:H7 in bovine feces.
The sensitivities of several plating and broth enrichment methods for the detection of Escherichia coli O157:H7 in (i) bovine fecal samples directly inoculated with E. coli O157:H7, (ii) fecal samples from cattle in herds previously positive for E. coli O157:H7, and (iii) fecal samples from calves shedding E. coli O157:H7 after experimental oral inoculation were compared. Three enrichment protocols and three plating protocols were evaluated with directly inoculated fecal samples. All broth enrichment methods were superior to direct plating when they were combined with subsequent plating on sorbitol-MacConkey with cefixime and tellurite (SMACct). SMACct was the most sensitive plating medium, and the three alternative broth enrichment methods gave similar improvements in sensitivity. Of 351 fecal samples from known positive herds, 24 samples (6.8%) were positive by one or more methods. By the most sensitive plating method, cultures of 10-g samples were slightly more sensitive (19 of 351 [5.4%]) than cotton-tipped swab fecal samples (14 of 351 [4.0%]); however, this difference was not significant. For samples from calves orally inoculated with E. coli O157:H7, separation by immunomagnetic beads was slightly more sensitive (79%) than broth enrichment followed by plating at two dilutions (10(-3) and 10(-4)) (71%); however, this difference was not significant. The combination of overnight enrichment of swab fecal samples (0.1 g) and plating on SMACct at two dilutions (10(-3) and 10(-4)) appears to be a sensitive method for detection in large-scale studies involving hundreds of samples per week.
Animals↗
Survey of dairy managers in the Pacific Northwest identifying factors associated with teat chapping.
Telephone interviews were conducted to evaluate the association of teat chapping with combinations of premilking and postmilking teat disinfectants (predip and postdip), other management practices, and climatic conditions. Holstein dairies (n = 100) in the DHIA SCC program were randomly selected from three northwest regions. During nonwinter seasons, herd managers using an iodophor dip without skin conditioner both premilking and postmilking were 9.7 times more likely to report chapping than were those using iodophor with conditioner. The herd managers least likely to report chapping problems were those using conditioner in both the predip and postdip. Use of conditioner in postdip only was associated with intermediate frequency of reported chapping. No conditioner in either predip or postdip was associated with the greatest frequency of reported chapping. Herd managers using a different germicide in the predip and postdip reported more chapping than herd managers using the same germicide. The frequency of chapping was highest during winter in all regions, and the percentage of herd managers reporting chapping within a region was associated with the temperature extremes of the region. For seasons other than winter, characteristics of predip and postdip combinations and parlor exit or barn design were the management factors that best described an association with reported chapping.
Animals↗
Effects of age on temperature-related variation in motor nerve conduction velocity in healthy chickens.
Muscle potentials evoked by stimulation of the sciatic nerve were evaluated in 4- and 15-week-old chickens. Each bird was anesthetized and slowly cooled externally from a normal body temperature of 40 C to 28 C, and motor nerve conduction velocities were measured at various intervals during cooling. Motor nerve conduction velocity decreased linearly with decreasing limb temperature in both groups. The rate of change in motor nerve conduction velocity per degree in 2 groups (2.13 m/s/C vs 1.84 m/s/C) fell just short of a statistically significant difference (P = 0.0508), indicating that an age-related effect on temperature-associated variation in motor nerve conduction velocity may be present.
Aging↗
Effect of exogenous prostaglandin F2 alpha in clinically normal postparturient dairy cows with a palpable corpus luteum.
In 228 clinically normal cows with a palpable corpus luteum 20 to 40 days after parturition and a mean 305-day mature equivalent milk production of 8,970 kg, prostaglandin F2 alpha was administered in a randomized, controlled clinical trial to determine whether such treatment enhanced their subsequent reproductive performance. Although the treatment reduced median time to first breeding by 4.5 days (P = 0.0025) from 57.0 days, median time to conception was not significantly different between the treatment and nontreated control group (87.0 vs 88.5 days) and conception rate by 110 days after parturition was not significantly different (64.7 vs 69.6%). Use of prostaglandin was associated with a significant (P = 0.0459) decrease in conception rate at first breeding from 42.0 to 29.3%. This study suggested that prostaglandin treatment of cows with a normal reproductive tract and a palpable corpus luteum at a median of 25 days after parturition does not enhance their reproductive performance and thus is not cost-effective.
Animals↗
Ecology of Staphylococcus aureus isolated from various sites on dairy farms.
The purposes of this study were to identify sources of Staphylococcus aureus on dairies and to determine whether S. aureus colonization of heifer body sites increases the risk of S. aureus IMI at parturition. In herds with high (> 10%) or low (< 3%) prevalence of S. aureus IMI, S. aureus was isolated from heifer teat skin, heifer external orifices, housing, feedstuffs, humans, nonbovine animals, air, and equipment. Additionally, in herds with high prevalence, S. aureus was isolated from bedding, insects, and water. The predominant sources of S. aureus for both groups were other IMI and heifer body sites. Heifers with prepartum lacteal secretions with S. aureus were at greater risk of S. aureus IMI at parturition than were prepartum heifers with lacteal secretions that were negative for S. aureus. Heifers with teat skin colonized by S. aureus were 3.34 times more likely to have S. aureus IMI at parturition than were noncolonized heifers. Overall, 35% of 700 heifers were colonized with S. aureus on a body site at least once. Although colonizations of most body sites appeared to be transient, a few heifers were colonized on the same site for 1 yr. Persistently colonized heifers may represent the primary reservoirs of S. aureus for other heifers.
Animals↗
Isolation of multiple Salmonella serovars from a dairy two years after a clinical salmonellosis outbreak.
Samples were obtained for bacteriologic culturing of salmonellae from cows and calves on, and the environment of, a large California dairy that used free-stall housing and a flush system for manure handling. Two years previously, the dairy had an outbreak of clinical salmonellosis in the lactating herd; however, since that time, it had not had problems with clinical salmonellosis. On the basis of mean annual milk production per cow, this dairy was consistently ranked in the top 25% of dairies in the area enrolled in the Dairy Herd Improvement Association. Results of bacteriologic culture of 76% (108/142) of environmental samples and 48% (639/1,339) of fecal samples were positive for salmonellae. Eighty-two percent of the isolates were serovar C1, subclassified as Salmonella montevideo, and 17% were serovar E. Results of bacteriologic culture of 85% of samples of recycled flush water being pumped into the free-stall alleys were positive, as were results of bacteriologic culture of 78% of samples of herd bulk milk filters, 97% of fecal samples collected from calves being fed nonsalable milk, and 25% of fecal samples collected from cows at the time of breeding. These findings suggest that freedom from clinical salmonellosis and comparatively high measures of herd performance do not indicate the absence of salmonellae from a premises, and that hardy infectious agents transmitted by ingestion of feces can become established in the environment of modern free-stall dairies that use recycled water in their manure flush systems.
Animals↗
Contagious mastitis.
Contagious mastitis is defined. The major mastitis pathogens are Streptococcus agalactiae, Staphylococcus aureus, Corynebacterium bovis, Mycoplasma sp, and Streptococcus dysgalactiae. These pathogens are discussed relative to prevalence, virulence factors, pathology, and control. These control measures include milking time hygiene, segregation, culling, vaccination, and treatment.
Animals↗
Interrelationships of somatic cell count, mastitis, and milk yield in a low somatic cell count herd.
In a high yielding low SCC herd, changes in milk yield associated with SCC and occurrence of clinical mastitis and differences in SCC with parity, clinical mastitis, and DIM were investigated. Milk yield data were obtained at every milking, and SCC was measured once every 48 h in 117 cows during the first 119 d postpartum. Effects of SCC and clinical mastitis on cumulative milk yield in the first 119 d postpartum were evaluated with least squares linear regression. Repeated measures ANOVA was used to detect changes in SCC. The SCC was highest at lactation onset, and cows with clinical mastitis had significantly higher SCC. During the 10 d prior to onset of clinical mastitis, SCC was higher in affected cows than in matched unaffected controls and surged just prior to diagnosis. During the 10-d period following a mastitis treatment, SCC differences between treated and control cows remained significant but became smaller with time and returned to the premastitis differences. Occurrence of clinical mastitis was associated with 5% milk yield loss. Cows with mean SCC > 245,000 cells/ml over the 119 d showed 6.2% yield loss compared with cows with SCC < or = 90,000 cells/ml. Cows with clinical mastitis had higher SCC prior to and following the end of treatment for mastitis than did controls. Clinical mastitis and SCC were associated with significant yield loss. Milk yield loss attributed to clinical mastitis was greater than that associated with elevated SCC (> 245,000 cells/ml) because a greater percentage of cows (26%) had clinical mastitis than elevated SCC (12.5%).
Animals↗
Microbiologic investigation of an epizootic of mastitis caused by Serratia marcescens in a dairy herd.
An epizootic of subclinical and clinical mastitis caused by Serratia marcescens was investigated in a 1,000-cow dairy farm in California. Serratia marcescens was isolated from 13 to 18% of composite milk samples obtained from lactating dairy cows. During monthly milk sampling performed during a 4-month period, S marcescens was isolated from 38.8 to 62.3% of composite milk samples obtained from cows from which S marcescens was previously isolated. Few cows infected with S marcescens had evidence of clinical mastitis. Somatic cell count value was associated with isolation of S marcescens. Cows with somatic cell counts greater than 500,000 were 5.48 times as likely to have intramammary infections with S marcescens, compared with cows with somatic cell count less than or equal to 500,000. Lactation number also was associated with S marcescens intramammary infection. After adjusting for the effect of lactation number, cows with high somatic cell count values were 2.98 times as likely to have intramammary infection with S marcescens, compared with cows with low somatic cell counts. Infection with S marcescens was independent of days in lactation, production string, and daily milk production. Eleven months after the beginning of the epizootic, S marcescens was isolated from organic bedding samples obtained from the dairy. Despite numerous attempts, other sources of S marcescens could not be identified on this dairy.
Animals↗
Diagnosis of Staphylococcus aureus intramammary infection by detection of specific antibody titer in milk.
The diagnostic value of the determination of Staphylococcus aureus antibody titer in milk as a method for identification of mammary quarters with S. aureus IMI was evaluated. Ten cows with a history of S. aureus IMI and 9 cows with no history of S. aureus IMI were sampled daily for 10 d. Quarter and composite milk samples were collected and processed by standard methods for concentration of S. aureus, S. aureus antibody titer (percentage of positive laboratory control), and SCC (cells per milliliter). Microbiologic culture identified 13 S. aureus-infected quarters from the 10 cows with a history of S. aureus IMI. Only 2 of the 130 samples (1.5%) from these infected quarters had undetectable concentrations of S. aureus. Antibody titers in milk from infected quarters of infected cows were below the previously established level considered to be indicative of IMI in 6 of 130 samples (4.6%). Four samples from infected quarters of infected cows had titers considered to be in the suspect range. The sensitivity of the antibody test was 83% (13% SE) when the suspect samples were included and 86% (12% SE) when they were not. Milk from uninfected quarters of cows with S. aureus IMI tended to have S. aureus antibody titers greater than the test's positive control, which would suggest that the quarters were infected with S. aureus. Antibody titer was below the infection threshold level in all pooled samples of uninfected cows, suggesting that the test correctly identified all cows free of S. aureus IMI.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗