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Abstract

Objective

To compare the sensitivity of polymerase chain reaction (PCR) with microbiological culture for detecting salmonellae in equine fecal samples and equine environmental swab specimens.

Design

Samples and specimens were tested by PCR and microbiological culture.

Sample Population

A fecal sample from each of 152 horses admitted consecutively to the clinic for evaluation by the outpatient service, 282 fecal samples from 110 hospitalized horses that had been submitted to the clinical microbiology laboratory, and 313 environmental swab specimens were examined.

Procedure

Each sample and specimen in the study was tested, using PCR and microbiological culture. Results of PCR and culture were compared.

Results

Significantly (P < 0.001) more fecal samples were positive by PCR than by microbiological culture. 26 of 152 (17.1%) fecal samples collected from horses admitted by the outpatient service were positive by PCR and none was positive by culture. 71 of 110 hospitalized horses were identified as positive by PCR, compared with 11 horses identified as positive by culture. All culture-positive horses were positive by PCR. Of the 11 culture-positive horses, 10 (90.9%) were identified as PCR positive after testing of the first sample submitted, compared with 7 (63.6%) by culture. All PCR-positive horses were detected after a total of 3 samples/horse were submitted, whereas as many as 5 samples/horse was required to identify all culture-positive horses. 8 of 313 environmental specimens were positive by PCR, and none was positive by culture.

Conclusion

The PCR method reported here was more sensitive, more rapid, and required submission of fewer samples or specimens than did microbiological culture for detecting salmonellae. (Am J Vet Res 1996;57:780–786)

Free access
in American Journal of Veterinary Research

Summary

A study was conducted to identify the clinical signs associated with impaction of the proventriculus in ostriches, to identify diagnostic aids, and to develop a surgical procedure for management of the disorder. Clinical signs indicating the need for surgical intervention included chronic inappetance, a change in fecal consistency or production, dehydration, weight loss, and failure to respond to laxatives. Diagnosis of impacted proventriculus was by abdominal radiography and external palpation. Impactions were caused by sand and rocks (5 ostriches), hay and sand (1 ostrich), and leaves (1 ostrich). After surgery, 5 of the ostriches were clinically normal within (mean) 1 week. One ostrich failed to regain a normal appetite until 2 weeks after surgery, and one juvenile ostrich died after surgery. Of the 6 ostriches that survived, 1 died 1 week after discharge from the hospital. The remaining birds survived without redevelopment of impaction.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objectives—To assess automated ribotyping for characterization of Pseudomonas aeruginosa isolates and to identify their type prevalence and geographic distribution.

Sample Population—39 human and 56 ruminant P aeruginosa isolates.

Procedures—Isolates were identified by use of bacteriologic techniques and automated PvuII-based ribotyping. Susceptibility to antimicrobials was tested in vitro. Data were analyzed for index of discrimination; prevalence ratio; geographic distribution of ribotypes found only in humans, only in cows, or only in goats (single-host ribotypes); and geographic distribution of ribotypes found in humans and ruminants (multihost ribotypes).

Results—All isolates were typeable (45 ribotypes, 35 single-host ribotypes). Ribotyping index of discrimination was 0.976. More isolates (45.3%) than expected yielded multihost ribotypes (22% of all ribotypes). Although 8.6% of single-host ribotypes were found in 4 or more isolates, 60% of multihost ribotypes were found in 4 or more isolates. Ninety percent of multihost ribotypes were isolated from different geographic areas, whereas 3.0% of singlehost ribotypes were isolated from different geographic areas. All ruminant isolates were susceptible to gentamicin and polymyxin B. In contrast, antibiogram profiles differed for human isolates from different geographic areas. Susceptibility to antimicrobials differentiated 6 isolates not distinguished by ribotyping.

Conclusions and Clinical Relevance—Automated ribotyping with PvuII discriminated more isolates than in vitro antimicrobial susceptibility. In combination, both tests provided more information than either test alone. Given the greater prevalence and geographic distribution of multihost ribotypes, immunocompromised humans and lactating ruminants may have a greater risk for disease if exposed to multihost P aeruginosa ribotypes, compared with single-host ribotypes. (Am J Vet Res 2001;62:864–870)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To investigate potential sources of an epizootic of listerial encephalitis, using molecular diagnostic and typing methods.

Sample Population

A flock of about 655 sheep.

Procedure

An epizootiologic investigation was performed. Clinical, feed, and environmental samples were tested for Listeria monocytogenes, using polymerase chain reaction and culture methods; recovered isolates were “fingerprinted,” using an automated ribotyping system.

Results

Listeria monocytogenes was recovered from brain specimens of 7 sheep with clinical signs of listerial encephalitis. All clinical isolates had fingerprints identical to those of isolates from farm equipment used to transport silage. Corn silage, which was not fed to the sheep, also contained L monocytogenes of the same pattern type as defined by ribotyping. Listeria monocytogenes was not isolated from the stored haylage designated for feeding the sheep (the cut-off point for isolation being < 102 colony-forming units/g).

Conclusions

Corn silage was implicated as the source of a listeriosis epizootic. It appears to have cross-contaminated the haylage destined for the sheep during handling with a front-end loader. Suspension of silage feeding coincided with cessation of listeriosis cases.

Clinical Relevance

Use of advanced molecular techniques can help to identify the sources and restrict the scope of an epizootic. In epizootics, a single L monocytogenes strain can lead to infection of multiple animals, with rapid progression of the disease. (Am J Vet Res 1997;58:733–737)

Free access
in American Journal of Veterinary Research

Abstract

Objectives

To develop a reference database for characterization of bovine Staphylococcus aureus and Streptococcus agalactiae strains by automated ribotyping and to use it to assess the discriminatory power of this typing procedure and the geographic distribution of Sta aureus and Str agalactiae strains in New York state dairy herds.

Sample Population

22 commercial dairy herds.

Procedure

Isolates of Sta aureus and Str agalactiae from bovine milk were identified by standard bacteriologic procedures, then typed by automated ribotyping. Antimicrobial susceptibility of isolates was tested in vitro. Two indicators made from the data were percentage of farms with multiple ribotypes and percentage of single ribotypes found in several geographic regions. Standard bacteriologic diagnosis, automated ribotyping, and determination of antibiograms (Kirby-Bauer method) also were done.

Results

Of 50 Sta aureus and 44 Str agalactiae isolates from composite milk samples of 12 and 10 herds, respectively, 18 and 14 ribotypes, respectively, were identified. The discriminatory power of automated ribotyping was approximately 0.96 (Hunter-Gaston's formula). A higher percentage of herds with Sta aureus had multiple ribotypes. The most common Sta aureus ribotypes tended to have broader geographic distribution. Some Sta aureus ribotypes were significantly associated with antibiotic resistance profiles.

Conclusions

Automated ribotyping appears to characterize bovine strains of bacteria associated with intramammary infections with a high discriminatory index. Potential applications include identification of strains that appear to have broad geographic distribution suggesting interfarm transfer, discrimination between recurrent versus new intramammary infections (ie, for control of Str agalactiae and Sta aureus), and evaluation of antibiotic therapy. (Am J Vet Res 1997;58:482–487)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate sensitivities at the herd level of test strategies used in the Voluntary Johne's Disease Herd Status Program (VJDHSP) and alternative test strategies for detecting dairy cattle herds infected with Mycobacterium paratuberculosis.

Design—Nonrandom cross-sectional study.

Sample Population—64 dairy herds from Pennsylvania, Minnesota, Colorado, Ohio, and Wisconsin. Fifty-six herds had at least 1 cow shedding M paratuberculosis in feces; the other 8 herds were free from paratuberculosis.

Procedure—For all adult cows in each herd, serum samples were tested for antibodies to M paratuberculosis with an ELISA, and fecal samples were submitted for bacterial culture for M paratuberculosis. Sensitivities at the herd level (probability of detecting infected herd) of various testing strategies were then evaluated.

Results—Sensitivity at the herd level of the testing strategy used in level 1 of the VJDHSP (use of the ELISA to test samples from 30 cows followed by confirmatory bacterial culture of feces from cows with positive ELISA result) ranged from 33 to 84% for infected herds, depending on percentage of cows in the herd with positive bacterial culture results. If follow- up bacterial culture was not used to confirm positive ELISA results, sensitivity ranged from 70 to 93%, but probability of identifying uninfected herds as infected was 89%.

Conclusions and Clinical Relevance—Results suggest that the testing strategy used in the VJDHSP will fail to identify as infected most dairy herds with a low prevalence of paratuberculosis. A higher percentage of infected herds was detected if follow-up bacterial culture was not used, but this test strategy was associated with a high probability of misclassifying uninfected herds. (J Am Vet Med Assoc 2002;220: 1053–1057)

Full access
in Journal of the American Veterinary Medical Association