Bryan Markey

Detection and quantification of leptospires in urine of dogs: a maintenance host for the zoonotic disease leptospirosis

Leptospirosis is a global zoonotic disease. Pathogenic Leptospira species, the causative agent of leptospirosis, colonize the renal tubules of chronically infected maintenance hosts such as dogs, rats and cattle. Maintenance hosts typically remain clinically asymptomatic and shed leptospires into the environment via urine. In contrast, accidental hosts such as humans can suffer severe acute forms of the disease. Infection results from direct contact with infected urine or indirectly, through contaminated water sources. In this study, a quantitative real-time PCR specific for lipL32 was designed to detect the urinary shedding of leptospires from dogs. The sensitivity and specificity of the assay was evaluated using both a panel of pathogenic Leptospira species and clinical microbial isolates, and samples of urine collected from experimentally infected rats and non-infected controls. The lower limit of detection was approximately 3 genome equivalents per reaction. The assay was applied to canine urine samples collected from local dog sanctuaries and the University Veterinary Hospital (UVH) at University College Dublin. Of 525 canine urine samples assayed, 37 were positive, indicating a prevalence of urinary shedding of leptospires of 7.05%. These results highlight the need to provide effective canine vaccination strategies and raise public health awareness.

Methicillin-resistant Staphylococcus aureus isolated from a veterinary surgeon and five dogs in one practice

Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from five dogs with wound discharges after surgical procedures at a veterinary practice, and MRSA with similar molecular and phenotypic characteristics was isolated from the nares of one veterinary surgeon in the practice. The pulsed-field gel electrophoresis patterns of all the isolates were indistinguishable from each other and from the most common human isolates of MRSA in Ireland.

Zoonotic transmission of Streptococcus equi subsp. zooepidemicus from a dog to a handler.

This is, to the best of our knowledge, the first case report to describe the apparent transmission of Streptococcus equi subsp. zooepidemicus from an infected dog to a handler who subsequently developed severe systemic infection. Characterization of the haemolytic streptococci isolated from both the patient and the dog, by phenotypic and molecular analysis, confirmed the canine and human isolates were identical.

Isolation of Mycoplasma bovis from bovine clinical samples in the Republic of Ireland

Mycoplasma bovis was detected in 134 (18 per cent) of 736 samples of bovine lung tissue collected from fatal pneumonia cases in the Republic of Ireland between April 1995 and December 1998. The cases occurred in 95 herds and recurred in four of them. Other respiratory pathogens were identified in 66 per cent of the M bovis-positive cases, with Pasteurelia species, infectious bovine rhinotracheitis and parainfluenza 3 virus being most frequently detected. Mastitis and arthritis were less common clinical signs associated with M bovis infection; 22 cases of M bovis mastitis and five cases of M bovis arthritis were diagnosed in five herds.

Prevalence and number of Salmonella in Irish retail pork sausages

A national Salmonella control program in the pork industry was enacted in Ireland in August 2002. This study was undertaken as part of a larger project investigating the role of pork as a source of human salmonellosis in Ireland. The objective of this survey was to assess the prevalence of Salmonella in Irish pork sausage at retail level. Samples, comprising branded prepacked sausages and loose sausages from supermarket meat counters and butcher shops, were collected from selected retail sites in four cities from October to December 2001 and from June to August 2002. A three-tube most-probable-number method was used to enumerate Salmonella in a selected number of samples that were positive by enrichment. Salmonella serotypes were detected in 4.4 and 1.7% of samples at each of the respective sampling periods, a level similar to those reported in other U.S. and U.K. studies. Isolates were characterized by serotype, phage type, and antimicrobial susceptibility. Eighteen (70%) were resistant to at least one antimicrobial, and 15 (58%) were resistant to four or more antimicrobials. Most of the isolates exhibited resistance to tetracycline. Five different phage types were detected. DT104 was the predominant phage type among Salmonella Typhimurium isolates. This study revealed that multidrug-resistant salmonellae are present in a proportion of Irish sausages and that further risk analysis work is necessary in order to quantify the risk posed to public health.

Isolation rates of meticillin-resistant Staphylococcus aureus in dogs, cats and horses in Ireland

A retrospective analysis and prospective surveillance study were conducted to determine isolation rates of meticillin-resistant Staphylococcus aureus (MRSA) in dogs, cats and horses in Ireland. Clinical samples that had been submitted to University College Dublin (UCD) for routine microbiological examination over a four-year period (2003 to 2006) were analysed in the retrospective analysis, which included clinical samples from 3866 animals. In the prospective surveillance study, samples from healthy animals presenting for elective surgery as well as from animals with a clinical presentation suggestive of MRSA infection were investigated. Animals attending 30 veterinary practices throughout Ireland and a similar population of animals presented to UCD were studied. The isolation rates for animals in the retrospective study were 1.1 per cent (32 of 2864) for dogs, 0.7 per cent (four of 619) for cats and 5.2 per cent (20 of 383) for horses. The overall isolation rate of MRSA was 1.4 per cent (56 of 3866). Isolation rates for healthy animals in the prospective study were 0.4 per cent (one of 286) for dogs and 1.7 per cent (four of 236) for horses; MRSA was not isolated from cats (0 of 47). Isolation rates for animals suspected of being infected with MRSA were 8.1 per cent (14 of 173) for dogs and 4.6 per cent (three of 65) for horses; MRSA was not isolated from cats (0 of 47).

Comparison of serological tests for the diagnosis of Chlamydia psittaci infection of sheep

An enzyme-linked immunosorbent assay (ELISA) was developed and compared with the complement fixation test (CFT) and the indirect immunofluorescence antibody test (IIFAT) for the detection of antibodies to C. psittaci in sheep. Field sera and experimental sera from aborting ewes, subclinically infected sheep and vaccinated sheep were used. The ELISA and IIFAT were much more sensitive than the CFT. Agreement between the CFT and ELISA varied between 50% and 98%, while agreement between the IIFAT and ELISA varied between 70.5% and 94.3%. The specificity of IIFAT and ELISA with regard to the identification of animals which may be a source of ovine abortion strains of C. psittaci was critically assessed, using antigen preparations derived from an abortion isolate and from a non-abortion isolate of C. psittaci. Indirect immunofluorescence was shown to be the more discerning test.

Persistence of Mycoplasma bovis infection in the mammary glands of lactating cows inoculated experimentally

To study the course of clinical mycoplasma mastitis and investigate its potential for persistence, 10(8) colony-forming units (cfu) of an Irish isolate of Mycoplasma bovis was inoculated aseptically into the right fore teat canal of three lactating cows. M bovis rapidly colonised the infected quarters and grew exponentially to more than 10(10) cfu/ml within the first three days, and spread to other quarters of each of the three cows within five to 10 days. After periods of between 24 and 72 hours the infected quarters became distended and sensitive to touch, and their secretions changed from containing visible particles, to a seropurulent exudate, to an aqueous suspension of fine particles which formed a sediment after a sample was collected. M bovis-specific antibody levels increased to varying degrees in all three cows. Subsequently, the concentrations of mycoplasma decreased to less than 10(7) cfu/ml in two of the cows, but remained at more than 10(8) cfu/ml to the end of the lactation of the other cow. Apparently normal milk was secreted by one of the cows within a month of the challenge, and by the other two cows at the start of their next lactation. However, in two of the cows subclinical M bovis infection persisted through the dry periods and into their next lactations.

Influences on antimicrobial prescribing behaviour of veterinary practitioners in cattle practice in Ireland

Guidelines on prudent antimicrobial use in veterinary medicine have been developed to reduce inappropriate prescribing of antimicrobials. Such guidelines focus mainly on the clinical and pharmacological indications for prescribing. A questionnaire study of veterinary surgeons engaged in cattle practice was completed to determine if non-clinical issues influence the decision to prescribe antimicrobials, and to assess if pharmacological and non-pharmacological issues influence the choice of antimicrobial prescribed. Non-clinical issues, including issues related to professional stress, influenced the prescribing decision of the majority of respondents. However, the nature of the veterinarian–client relationship did not influence the prescribing behaviour of the majority of respondents. Pharmacological and non-pharmacological issues influenced the choice of antimicrobial prescribed. The veterinary surgeons prior experience of a drug was considered ‘often’ or ‘always’ by 95.7 per cent of respondents when making this decision. The findings of this study have implications for the recognition and management of stress within the profession, and for the development of intervention strategies to reduce inappropriate antimicrobial prescribing.

Detection and quantification of Toxoplasma gondii in ovine maternal and foetal tissues from experimentally infected pregnant ewes using real-time PCR.

A real-time PCR (rt-PCR) targeting the 529-bp repeat element (RE) of Toxoplasma gondii was used to detect and quantify the parasite burden in maternal and foetal tissues in 18 seronegative ewes infected with 3000 toxoplasma oocysts on day 90 of pregnancy. The infected ewes were sacrificed in groups of 4-6 at 21, 25, 33 and 35 days post-challenge. Ten sham inoculated pregnant ewes were used as controls. T. gondii was not detected in the control ewes or their foeti. The parasite was only detected in the maternal tissues in a few of the challenged ewes on a small number of occasions where it was identified in spleen and uterine lymph nodes. T. gondii was detected in the foetal spleen and liver at the early sacrifice times but only sporadically thereafter. In the case of amniotic, allantoic and foetal aqueous humor samples T. gondii was only detected on a small number of occasions. However, it was found in the majority of the foetal lung and placentome samples throughout the study period, while placentomes and foetal brains contained high levels of the parasite during the later stages. Histopathological examination of placentome and brain tissue from the foeti in the present study revealed a strong correlation between histopathological lesions and quantities of the parasite DNA detected. These results indicate that the cotyledonary component of the foetal membranes is the sample of choice for the diagnosis of T. gondii by rt-PCR, followed by foetal lung and brain.