kevina mcgill | University College Dublin (original) (raw)

Papers by kevina mcgill

Journal of Comparative Pathology, Nov 1, 1986

Zoonoses and Public Health, 2009

SummaryFive culture methods for the recovery of Campylobacter species (spp.) were evaluated on 36... more SummaryFive culture methods for the recovery of Campylobacter species (spp.) were evaluated on 361 rectal swabs collected from cats and dogs in Ireland. Speciation using PCR methods was performed on all isolates to assess the sensitivity of each culture method for isolation of Campylobacter spp., and to establish the prevalence of Campylobacter jejuni, C. coli, C. upsaliensis, C. lari and C. helveticus. Overall 163 of 361 (45.2%) samples were confirmed Campylobacter spp. positive. Direct plating onto modified charcoal cefoperazone deoxycholate agar (mCCDA) with cefoperazone, amphotericin and teicoplanin (CAT) selective supplement yielded a significantly higher prevalence of Campylobacter spp. (33.0%) than each of the other four methods (P ≤ 0.05). This method was also the most sensitive method for isolation of C. upsaliensis compared with any of the other four methods used in the current study (P ≤ 0.05). A direct plating method onto mCCDA agar with CCDA selective supplement and a f...

Infection ecology & epidemiology, 2016

Campylobacter jejuni is the leading bacterial food-borne pathogen within the European Union, and ... more Campylobacter jejuni is the leading bacterial food-borne pathogen within the European Union, and poultry meat is an important vehicle for its transmission to humans. However, there is limited knowledge about how this organism persists in broiler litter and faeces. The aim of this study was to assess the impact of a number of environmental parameters, such as temperature, humidity, and oxygen, on Campylobacter survival in both broiler litter and faeces. Used litter was collected from a Campylobacter-negative broiler house after final depopulation and fresh faeces were collected from transport crates. Samples were confirmed as Campylobacter negative according to modified ISO methods for veterinary samples. Both sample matrices were inoculated with 9 log10 CFU/ml C. jejuni and incubated under high (≥85%) and low (≤70%) relative humidity conditions at three different temperatures (20°C, 25°C, and 30°C) under both aerobic and microaerophilic atmospheres. Inoculated litter samples were th...

Research in Veterinary Science

Tuberculin Purified Protein Derivatives (PPDs) exhibit multiple limitations: they are crude extra... more Tuberculin Purified Protein Derivatives (PPDs) exhibit multiple limitations: they are crude extracts from mycobacterial cultures with largely unknown active components; their production depends on culture of mycobacteria requiring expensive BCL3 production facilities; and their potency depends on the technically demanding guinea pig assay. To overcome these limitations, we developed a molecularly defined tuberculin (MDT) by adding further antigens to our prototype reagent composed of ESAT-6, CFP-10 and Rv3615c (DIVA skin test, DST). In vitro screening using PBMC from infected and uninfected cattle shortlisted four antigens from a literature-based list of 18 to formulate the MDT. These four antigens plus the previously identified Rv3020c protein, produced as recombinant proteins or overlapping synthetic peptides, were formulated together with the three DST antigens into the MDT to test cattle experimentally and naturally infected with M. bovis, uninfected cattle and MAP vaccinated ca...

Genotypic characterisation and cluster analysis of Campylobacter jejuni isolates from domestic pe... more Genotypic characterisation and cluster analysis of Campylobacter jejuni isolates from domestic pets, human clinical cases and retail food

Scientific Reports, 2021

Veterinary immunology and immunopathology, 2017

The measurement of bovine interferon-gamma (IFN-γ) forms the basis of a diagnostic test for bovin... more The measurement of bovine interferon-gamma (IFN-γ) forms the basis of a diagnostic test for bovine tuberculosis where Mycobacterium bovis sensitised effector T cells produce IFN-γ following in vitro stimulation with tuberculin antigens. In cattle infected with M. bovis it is also known that the anti-inflammatory IL-10 cytokine can inhibit in vitro production of IFN-γ leading to a reduced response in the IFN-γ diagnostic test. In order to investigate this in greater detail, whole blood samples from tuberculin skin test positive and negative cattle were stimulated with bovine and avian tuberculin antigens and in parallel with a neutralising anti-IL-10 monoclonal antibody. The results showed that IFN-γ protein levels increased when IL-10 activity was suppressed by Anti - IL-10. By using a standard diagnostic interpretation, the elevated levels of IFN-γ were shown to change the level of agreement between the performance of the single intradermal comparative tuberculin test (SICTT) and I...

Journal of Integrative Agriculture, 2016

This study compared the impact of three indirect heating systems to direct gas flame heaters on a... more This study compared the impact of three indirect heating systems to direct gas flame heaters on a selection of flock performance and environmental indicators in commercial broiler units. No statistically significant differences (P≥0.05) were found in flock mortality rates, bird weight, water consumption, stress response, carbon dioxide, ammonia, temperature, relative humidity, litter quality, within-flock Campylobacter levels or mean Campylobacter counts when flock data from any of the three indirect heating systems were compared to flocks reared in houses with direct heating systems. Differences in litter quality were observed between upper and lower litter layers in all houses, regardless of heating type, which may have implications for bird health and welfare. Carbon dioxide concentrations in houses with direct heating systems were significantly higher than those in houses with indirect heating systems during the first 10 days of bird life (P≤0.05). This was due to the increased use of heating systems during this period of the flock cycle. Differences in CO 2 concentrations had no effect on flock performance, possibly due to the fact that concentrations did not exceed known safe levels. A statistically significant increase in stress response was observed in birds as a result of partial depopulation (thinning) within houses, irrespective of heating system type used (P≤0.05). Stress associated with thinning may have consequences for bird welfare and food safety. In conclusion, the results of our study suggest that indirect heating systems do not appear to negatively impact on flock performance, stress response, within-flock Campylobacter levels or mean Campylobacter counts and do not appear to significantly alter environmental conditions within broiler houses when compared to houses equipped with direct heating systems. Indirect systems are a viable alternative for heating broiler houses in terms of flock performance, bird welfare and food safety.

Infection Ecology & Epidemiology, 2016

Background: Campylobacter jejuni is the leading bacterial food-borne pathogen within the European... more Background: Campylobacter jejuni is the leading bacterial food-borne pathogen within the European Union (EU), and poultry meat is the primary route for transmission to humans. Material and methods: This study examined the impact of partial depopulation (thinning), season, and farm performance (economic, hygiene, and biosecurity) on Campylobacter prevalence in Irish broilers over a 13-month period. Ten caecal samples were taken per flock, for a total of 211 flocks from 23 farms during the duration of the study. Campylobacter was isolated and enumerated according to modified published ISO methods for veterinary samples. Biosecurity was evaluated through a questionnaire based on risk factors for Campylobacter identified in previous studies. Hygiene compliance was assessed from audit records taken over the course of 1 year. All information relating to biosecurity and hygiene was obtained directly from the processing company. This was done to ensure farmers were unaware they were being monitored for Campylobacter prevalence and prevent changes to their behaviour. Results and discussion: Farms with high performance were found to have significantly lower Campylobacter prevalence at first depopulation compared with low-performance farms across all seasons (P50.01). Peak Campylobacter levels were observed during the summer season at first thin in both the high-and lowperformance groups. Campylobacter prevalence was found to increase to ]85% in both high-and lowperformance farms across all seasons at final depopulation, suggesting that Campylobacter was introduced during the first depopulation. On low-performance farms, four biosecurity interventions were found to significantly reduce the odds of a flock being Campylobacter positive (physical step-over barrier OR 00.17, house-specific footwear OR 00.13, absence of water body within 0.5 km OR 00.13, two or more broiler houses on a farm OR00.16), compared with farms without these interventions. For high-performance farms, no single biosecurity intervention was identified as significant as this group had full compliance with multiple factors. High-performance farms had significantly better feed conversion ratios compared with lowperformance farms (1.61 v 1.67 (P50.01)). No differences in flock mortality rates were observed (P ]0.05). This highlights the impact of season, biosecurity, partial depopulation, and farm performance on Campylobacter prevalence in Irish broilers.

PLOS ONE, 2016

The most widely used ante-mortem diagnostic tests for tuberculosis in cattle are the tuberculin s... more The most widely used ante-mortem diagnostic tests for tuberculosis in cattle are the tuberculin skin test and the interferon-gamma (IFN-γ) release assay, both of which measure cellmediated immune responses to Mycobacterium bovis infection. However, limitations in the performance of these tests results in a failure to identify all infected animals. In attempting to increase the range of diagnostic tests for tuberculosis, measurement of the cytokine IP-10 in antigen-stimulated blood has previously been shown to improve the detection of M. tuberculosis and M. bovis infection, in humans and African buffaloes (Syncerus caffer), respectively. In the present study, 60 cattle were identified by the single intradermal comparative tuberculin test as tuberculosis reactors (n = 24) or non-reactors (n = 36) and the release of IFN-γ and IP-10 in antigen-stimulated whole blood from these animals was measured using bovine specific ELISAs. There was a strong correlation between IP-10 and IFNγ production in these samples. Moreover, measurement of the differential release of IP-10 in response to stimulation with M. bovis purified protein derivative (PPD) and M. avium PPD distinguished between reactor and non-reactor cattle with a sensitivity of 100% (95% CI, 86%-100%) and a specificity of 97% (95% CI, 85%-100%). These results suggest that IP-10 might prove valuable as a diagnostic biomarker of M. bovis infection in cattle.

Journal of Food Safety, 2002

ABSTRACT Commercial immersion chilling systems used in poultry processing are a major source in t... more ABSTRACT Commercial immersion chilling systems used in poultry processing are a major source in the cross-contamination of carcasses with pathogenic microorganisms. In the current study, the efficacy of a chlorine based bactericidal compound, sodium ...

Foodborne Pathogens and Disease, 2009

The presence of antimicrobial resistance in 51 Campylobacter jejuni isolates obtained from cats a... more The presence of antimicrobial resistance in 51 Campylobacter jejuni isolates obtained from cats and dogs was determined by E-testing. Resistance to nalidixic acid (37.3% of isolates), ciprofloxacin (19.6%), tetracycline (13.7%), ampicillin (13.7%), erythromycin (11.8%), and chloramphenicol (5.9%) was detected. Resistance to two antimicrobials or more was present in 31.4% of isolates, and one isolate was resistant to all six antimicrobials. Of the isolates with ciprofloxacin and=or nalidixic acid resistance, 54.5% had the gyrA substitution Thr-86-Ile on sequencing. The tet o gene was detected in 75.0% isolates with high-level resistance to tetracycline. With the observed antimicrobial resistance in C. jejuni isolates from pets in this study, and the detection of identical mechanisms for quinolone and tetracycline resistance in pets and humans, pets should be considered a potential source of (multi)resistant C. jejuni infections in humans.

Department of Agriculture, Food and the MarineTeagascDeposited by bulk impor

Journal of Food Safety, 2003

ABSTRACT A study of the prevalences of Salmonella, Listeria and thermophilic campylobacters in a ... more ABSTRACT A study of the prevalences of Salmonella, Listeria and thermophilic campylobacters in a dedicated commercial poultry feed mill was undertaken. Salmonella was frequently recovered in samples taken in the preheat and postheat treatment areas of ...

International journal of food microbiology, 2015

Extended spectrum β-lactamase (ESBL) producing Escherichia coli have emerged as a contaminant on ... more Extended spectrum β-lactamase (ESBL) producing Escherichia coli have emerged as a contaminant on modified charcoal cefoperazone deoxycholate agar (mCCDA) when attempting to selectively isolate Campylobacter spp. from poultry. E. coli are particularly problematic given their ability to grow under microaerophilic conditions and have been shown to outcompete Campylobacter species making Campylobacter detection or enumeration difficult. This paper recommends a novel method for restoring the selectivity of mCCDA using tazobactam, a β-lactamase inhibitor. The method significantly inhibited ESBL E. coli growth in spiked or naturally contaminated broiler caecal samples (p≤0.01) when compared to conventional mCCDA. This effect was seen at concentrations as low as 1mg/L tazobactam. TmCCDA(1) was found to inhibit up to 8log10CFU/mL of ESBL E. coli in mixed pure cultures and 7.5log10CFU/mL in caecal samples. Furthermore TmCCDA concentrations up to 10mg/L had no statistically significant inhibit...

International Journal of Food Microbiology

The aim of the current study was to assess the ability of a number of chemicals (acetic Acid (AA)... more The aim of the current study was to assess the ability of a number of chemicals (acetic Acid (AA), citric acid (CA) lactic acid (LA), sodium decanoate (SD) and trisodium phosphate (TSP)) to reduce microbial populations (total viable count, Campylobacter jejuni, Escherichia coli, Salmonella typhimurium and Listeria monocytogenes) on raw beef using an immersion system. The following concentrations of each chemical were used: 3 &amp;amp;amp;amp;amp;amp;amp;amp; 5% for AA, CA, LA, SD and 10 &amp;amp;amp;amp;amp;amp;amp;amp;12% for TSP. Possible synergistic effects of using combinations of two chemicals sequentially (LA+CA and LA+AA) were also investigated. L*, a* and b* values were measured before and after treatments and ΔE* values were calculated in order to determine any changes in the color of meat due to the use of these chemicals. In general, all chemical treatments resulted in significantly (p&amp;amp;amp;amp;amp;amp;amp;lt;0.05) reduced bacterial counts when compared to untreated controls. The greatest reductions were obtained by using LA3%, SD5%, AA5%, LA5% and SD3% for TVC, C. jejuni, E. coli, S. typhimurium and L. monocytogenes, respectively. However, no significant difference in microbial load was observed between the different concentrations of each chemical used (p&amp;amp;amp;amp;amp;amp;amp;gt;0.05). The application of combinations of chemical immersion treatments (LA3%+AA3% and LA3%+CA3%) did not result in further significant reductions in microbial populations when compared to single chemical treatments (P&amp;amp;amp;amp;amp;amp;amp;lt;0.05). Assessment of color changes in meat following the application of chemical immersion treatments indicated that using AA or CA at either concentration and LA at 5% led to an increase in the ΔE* value of &amp;amp;amp;amp;amp;amp;amp;gt;3 immediately after treatment and after 24h storage. The remaining treatments did not result in significant changes to the color of raw beef.

Irish Veterinary Journal

The γ-interferon assay was evaluated in 203 M. bovis-infected cattle which had previously been id... more The γ-interferon assay was evaluated in 203 M. bovis-infected cattle which had previously been identified by the single intradermal comparative tuberculin test, and in 923 cattle from 13 herds which were considered free of tuberculosis. Eight methods were used to interpret the results and the proportion of infected cattle giving a positive result range A from 56.2% to 87.7%. The proportion of cattle from herds considered free of tuberculosis giving a positive result ranged from 3.4% to 11.9%. These results suggest that the γ-interferon assay is worthy of further investigation for the diagnosis of tuberculosis in cattle in Ireland.