An investigation of the frequency of detection of fluoroquinolone residues in the muscle of broiler chickens sold at supermarkets and pluck shops in Trinidad

Objective: Fluoroquinolones are broad spectrum antimicrobials, used to treat a wide myriad of gastrointestinal, genitourinary and respiratory infections in both humans and animals. They are also used prophylactically in livestock including poultry and fish. this occurrence, coupled with the abuse of the drug due to extra-label and improper use, have led to concerns about both antimicrobial resistance to these drugs and the presence of their residues in veterinary products such as meat. Tremendous human health issues inclusive of antimicrobial resistance, anaphylactic reactions, carcinogenicity, mutagenicity, teratogenicity and the disruption of normal flora can occur due to the use and abuse of these antimicrobials. We hypothesized that fluoroquinolones residues are present in the meat of broiler chickens in Trinidad. Hence, our objectives were to detect the presence and concentrations of fluoroquinolone residues in broiler chickens sold at supermarkets and pluck shops in Trinidad. Design and Methodology: A total of 168 carcasses were sampled from supermarkets and pluck shops across Trinidad and Tobago, during July to August of 2018. The breast muscles were removed and subjected to first the extraction process then to the Ridascreen® Chinolone/Quinolones Enzyme Linked- Immunosorbent Assay (ELISA) to determine the presence and concentrations of fluoroquinolones in these samples. Results: Fluoroquinolone residues were detected at a frequency 14.3% (24/168), with concentrations ranging from 5.53-161.41µg/kg and 2.4% (4/168) of carcasses contained fluoroquinolones at levels higher than (100 µg/kg) that stipulated by the Codex Alimentarius. Conclusion: Fluoroquinolones are present in broiler chickens sold in Trinidad. Its presence, at times higher than the recommended levels, has serious public health implications.

Escherichia coli contamination of lettuce sold at markets in Trinidad: A preliminary study

Objective: Historically most foodborne disease outbreaks have been attributed to animal products but recently the number of cases associated with vegetable produce has been increasing. Most of these microbial foodborne pathogens are also part of the resident gut flora of many animals and can be shed asymptomatically in the environment. Leafy greens contamination with these pathogens are of particular concern since they are consumed uncooked. Using Escherichia coli (E. coli) as an indicator of faecal contamination, we evaluated lettuce as a potential source of foodborne disease. Design and Methodology: A cross-sectional study was carried out targeting six retail markets in Trinidad. At each market, a total of 15 lettuce samples were purchased from five retailers. The E. coli colony forming units per gram (CFU/g) of lettuce were then assessed using standard laboratory techniques. Results: All farmers surveyed reported using pipe-borne water as their primary source of irrigation water. E. coli was present in all samples. Overall, the E. coli counts ranged from 0.8 to 80,000 CFU/gram. The lettuce E. coli counts varied with location (p=0.01) and was highest in San Fernando (3.4 ± 1.1 Log10CFU/g) and lowest in Marabella (1.5 ± 0.65 Log10 CFU/g). Interestingly, lettuce farms using manure had lower E. coli counts than those not using manure (2.88 ± 1.3 Log10 CFU/g vs 2.27±1.23 Log10 CFU/g; p=0.07.) Conclusion: These high E.coli counts are indicative of either preharvest or post-harvest faecal contamination of lettuce. The high level of E. coli contamination of lettuce being sold at market should be of serious concern since this a potential risk to public health.

A comparison of the efficacy of two commercial acaricides (fipronil and amitraz) with Azadirachta indica (neem) on the brown dog tick (Rhipicephalus sanguineus) from canines in Trinidad

Objective: Rhipicephalus sanguineus, the most common species of tick found on canines in Trinidad. It is a potential vector for potentially fatal zoonotic diseases such as borreliosis (Lyme disease), babesiosis, anaplasmosis and human granulocytic ehrlichiosis. Common acaricides used by pet owners such as fipronil and amitraz are often misused and abused as owners may fail to follow the manufacturers' instructions. The objectives of this study were to compare the efficacies of the commercial acaricides (fipronil and amitraz) to the herbal alternative, neem on brown dog ticks in Trinidad. Design and Methodology: The Larval Packet Test (LPT) was conducted in triplicate for each of three concentrations (high, recommended and low concentrations) of fipronil, amitraz, neem oil and neem leaf extract. STATA version 15 was used to perform a mixed effects Poisson regression analysis. Results: Both the commercial and herbal acaricides were effective in causing death of the larvae. Larvae were susceptible to amitraz and fipronil at all concentrations used, however they displayed variable resistance to the neem oil and neem leaf extract. Conclusions: The commercial preparations (amitraz and fipronil) proved to be more effective than neem oil and neem leaf extract, however the latter can be used as a herbal alternative to control R. sanguineus in Trinidad.

A study of the histological classification and grading of canine malignant mammary tumours in Trinidad

Objective: Mammary gland tumors are a common occurrence in dogs, cats and humans but a rarity in other species. Histologically, grading these tumors evaluates the relevant prognostic variables which may be useful in treatment. The objective of this study was to classify canine malignant mammary tumours according to their morphological and staining characteristics using a standardized histologic classification scheme. Design and Methodology: A total of n = 78 canine mammary gland tumours (CMTs) were diagnosed during the period March 2013 to April 2017. CMTs were evaluated subsequent to routine tissue processing for microscopic evaluation followed by statistical analyses. Results: The two main tumour groups examined were malignant epithelial neoplasms and malignant epithelial neoplasms ­ special types, n= 69 (88.5%) and n= 9 (11.5%) respectively. The majority, n= 62 (79.5%) of tumours were classified as low grade or well differentiated (grade 1), n= 14 (17.9%) of tumours were intermediate grade or moderately differentiated (grade 2) and n= 2 (2.6%) of tumours were classified as high grade or poorly differentiated (grade 3). The significance of age or breed predilection could not fully be determined with this small sample size n = 78, however, all the dogs in this study were female. Conclusion: This study is the first of its kind to be conducted in Trinidad, which fully applies a standardized classification scheme as an independent prognostic indicator of CMTs.

A review of neoplastic and non-neoplastic canine skin tumours in Trinidad from 2010-2015

This retrospective study was performed on samples submitted to the Pathology Unit of the School of Veterinary Medicine, Faculty of Medical Sciences, St. Augustine, Trinidad, during the period 2010 to 2015. A total of 471 non-inflammatory cutaneous masses were analyzed, of which 225 (47.8%) were malignant, 202 (42.9%) were benign and 44 (9.3%) were non-neoplastic. The most common malignant tumors were haemangiosarcoma, 50 (22.2%); mast cell tumour, 49 (21.8%); soft tissue sarcoma 35 (15.6%), lymphoma, 20 (8.9%) and melanoma 20 (8.9%). The most common benign tumors were haemangioma, 39 (19.3%); lipoma, 27 (13.4%), trichoblastoma, 26 (12.9%), histiocytoma 25 (12.4%), plasma cell tumor, 23 (11.4%) and papilloma 9 (4.5%). Common non-neoplastic skin lesions included collagen naevi, 26 (59.1%) and follicular cysts, 11 (25.0%). Mixed breed dogs 241 (51.2%), was most frequently represented with neoplasms followed by Rottweilers 50 (10.6%) and Pit bulls 48 (10.1%).

Antimicrobial susceptibility of Leptospira isolates from dogs and rats to 12 antimicrobial agents.

This study determined the antimicrobial susceptibilities of 67 isolates of Leptospira from dogs (suspect canine cases: n=7 and stray dogs: n=6) and rodents (n=54) in Trinidad to 12 antimicrobial agents using broth microdilution and macrodilution techniques. Commonly used antimicrobial agents such as the penicillin G and ceftriaxone had relatively low minimal inhibitory concentrations (MICs) while doxycycline displayed a relatively higher value but was still considered to be effective. While imipenem was the most effective with low MIC values in vitro, sulphamethoxazole-trimethoprim had the highest i.e. least effective. Based on these results, the drugs commonly used in the treatment of leptospirosis (penicillin G, penicillin-streptomycin, doxycycline and ceftriaxone) in both humans and animals in Trinidad appear to have similar MICs and MBCs in vitro when compared with published reports. The serovar of Leptospira spp. and in most cases the origin of the isolates did not significantly (P>0.05) influence their susceptibilities to the antimicrobial agents tested.

Antimicrobial susceptibility of Leptospira isolates from dogs and rats to 12 antimicrobial agents

This study determined the antimicrobial susceptibilities of 67 isolates of Leptospira from dogs (suspect canine cases: n=7 and stray dogs: n=6) and rodents (n=54) in Trinidad to 12 antimicrobial agents using broth microdilution and macrodilution techniques. Commonly used antimicrobial agents such as the penicillin G and ceftriaxone had relatively low minimal inhibitory concentrations (MICs) while doxycycline displayed a relatively higher value but was still considered to be effective. While imipenem was the most effective with low MIC values in vitro, sulphamethoxazole-trimethoprim had the highest i.e. least effective. Based on these results, the drugs commonly used in the treatment of leptospirosis (penicillin G, penicillin-streptomycin, doxycycline and ceftriaxone) in both humans and animals in Trinidad appear to have similar MICs and MBCs in vitro when compared with published reports. The serovar of Leptospira spp. and in most cases the origin of the isolates did not significantly (P>0.05) influence their susceptibilities to the antimicrobial agents tested

Seroepidemiology of leptospirosis in dogs and rats in Trinidad.

Stray dogs (n=207), suspected canine cases of leptospirosis (n=50) and rats (n=200) from the Caribbean island of Trinidad were subjected to the Microscopic Agglutination Test (MAT) for leptospirosis. The seroprevalence in stray dogs was 15.5% (n=32), the predominant serogroup was Icterohaemorrhagiae (14.5%; n=30) with agglutinations to serovars Copenhageni at 5.8%, Icterohaemorrhagiae at 4.8%, Mankarso at 3.9%. The seroprevalence among suspected canine cases was 72% (n=36) with Icterohaemorrhagiae again being the predominant serogroup at 60% inclusive of serovars: Copenhageni, 44%; Mankarso, 14%; and Icterohaemorrhagiae 2%. A seroprevalence of 16.5% was determined in rats, all agglutinations were to the Icterohaemorrhagiae serogroup (inclusive of serovars Copenhageni, 9.5%; Icterohaemorrhagiae, 5.5%; and Mankarso, 1.5%). Overall serovar Copenhageni was the most common serovar as 11.6% of all the animal species tested by the MAT were positive and may be an important zoonotic serovar in Trinidad. The titres of infecting serovars of Leptospira in suspected canine cases of leptospirosis were considerably higher than that found in stray dogs and in rats where the lowest titres were found. Age and sex were not significant risk factors except in the case of rats where age was significant, indicating that juvenile rats were at a significantly higher risk. There was no definite pattern of the distribution of positive animals or the serovars when using the MAT. Data obtained in the current study indicate that dogs and rats in Trinidad have the potential to be sources of leptospiral infections for humans. This potential has public health implications making it imperative to control rat and stray dog populations in the island to reduce the risk of human leptospirosis.

Seroepidemiology of leptospirosis in dogs and rats in Trinidad

Stray dogs (n=207), suspected canine cases of leptospirosis (n=50) and rats (n=200) from the Caribbean island of Trinidad were subjected to the Microscopic Agglutination Test (MAT) for leptospirosis. The seroprevalence in stray dogs was 15.5% (n=32), the predominant serogroup was Icterohaemorrhagiae (14.5%; n=30) with agglutinations to serovars Copenhageni at 5.8%, Icterohaemorrhagiae at 4.8%, Mankarso at 3.9%. The seroprevalence among suspected canine cases was 72% (n=36) with Icterohaemorrhagiae again being the predominant serogroup at 60% inclusive of serovars: Copenhageni, 44%; Mankarso, 14%; and Icterohaemorrhagiae 2%. A seroprevalence of 16.5% was determined in rats, all agglutinations were to the Icterohaemorrhagiae serogroup (inclusive of serovars Copenhageni, 9.5%; Icterohaemorrhagiae, 5.5%; and Mankarso, 1.5%). Overall serovar Copenhageni was the most common serovar as 11.6% of all the animal species tested by the MAT were positive and may be an important zoonotic serovar in Trinidad. The titres of infecting serovars of Leptospira in suspected canine cases of leptospirosis were considerably higher than that found in stray dogs and in rats where the lowest titres were found. Age and sex were not significant risk factors except in the case of rats where age was significant, indicating that juvenile rats were at a significantly higher risk. There was no definite pattern of the distribution of positive animals or the serovars when using the MAT. Data obtained in the current study indicate that dogs and rats in Trinidad have the potential to be sources of leptospiral infections for humans. This potential has public health implications making it imperative to control rat and stray dog populations in the island to reduce the risk of human leptospirosis.

Study on the efficacy of Leptospira vaccines developed from serovars isolated from Trinidad and comparison with commercial vaccines using a hamster model.

A hamster model was used to determine the efficacy of commercially prepared canine vaccines against Leptospira serovars circulating in Trinidad and to assess the effectiveness of killed whole-cell vaccines prepared from local isolates. The local isolates used for vaccine preparation and challenge were isolates of serovars Copenhageni and Mankarso obtained from a local dog and rodent. Their estimated lethal dose-50 (LD(50)) were 5 and 10 organisms, respectively and clinical signs observed on infection were consistent with leptospirosis. An unvaccinated control group of hamsters and other groups of hamsters that had been vaccinated with 3 doses of (i) in-house whole-cell Copenhageni vaccine, (ii) in-house whole-cell Mankarso vaccine, (iii) commercial vaccine Brand A or (iv) commercial vaccines Brand B were challenged with 1000 times the LD(50) of the respective challenge serovar. The most commonly used commercial vaccine (Brand A) did not offer protection to challenged hamsters, whereas Brand B facilitated the renal carrier state of the Leptospira organism. In contrast the whole-cell vaccines developed from local strains of serovars Copenhageni and Mankarso, protected all hamsters tested from both clinical disease and renal carrier states.

Study on the efficacy of Leptospira vaccines developed from serovars isolated from Trinidad and comparison with commercial vaccines using a hamster model

A hamster model was used to determine the efficacy of commercially prepared canine vaccines against Leptospira serovars circulating in Trinidad and to assess the effectiveness of killed whole-cell vaccines prepared from local isolates. The local isolates used for vaccine preparation and challenge were isolates of serovars Copenhageni and Mankarso obtained from a local dog and rodent. Their estimated lethal dose-50 (LD(50)) were 5 and 10 organisms, respectively and clinical signs observed on infection were consistent with leptospirosis. An unvaccinated control group of hamsters and other groups of hamsters that had been vaccinated with 3 doses of (i) in-house whole-cell Copenhageni vaccine, (ii) in-house whole-cell Mankarso vaccine, (iii) commercial vaccine Brand A or (iv) commercial vaccines Brand B were challenged with 1000 times the LD(50) of the respective challenge serovar. The most commonly used commercial vaccine (Brand A) did not offer protection to challenged hamsters, whereas Brand B facilitated the renal carrier state of the Leptospira organism. In contrast the whole-cell vaccines developed from local strains of serovars Copenhageni and Mankarso, protected all hamsters tested from both clinical disease and renal carrier states.

Serovars of Leptospira isolated from dogs and rodents.

We determined the frequency of isolation of Leptospira from dogs and rodents, the serovars of Leptospira, and the clinical, gross and histological manifestations in dogs with leptospirosis in Trinidad. From dogs, samples of urine, blood and kidney were collected while only kidney and blood samples of trapped rodents were used. Isolates were cultured and serotyped using a panel of 23 international serovars and monoclonal antibodies. The risk factors for leptospirosis were also determined in owned dogs using a standard questionnaire. Of a total of 468 animals investigated for Leptospira, 70 (15.0%) were positive, comprising nine (18.0%) of 50 suspected canine leptospirosis cases, seven (3.4%) of 207 stray dogs and 54 (25.6%) of 211 rodents. The observation that rodents have a statistically (P<0.05, chi2) higher frequency of isolation emphasizes the importance of rodents as reservoirs of leptospirosis in the country. Copenhageni was the predominant serovar found in 100.0% (7/7), 33.3% (2/6) and 68.5% (37/54) of isolates from suspected canine leptospirosis cases, stray dogs and rodents, respectively. Serovars Icterohaemorrhagiae and Canicola, the two serovars present in the commercial vaccines used locally, were detected in one (1.5%) and zero (0.0%) isolates respectively of the 67 tested. Data provided suggest that the apparent vaccine failure may be a consequence of the fact that the predominant serovar (Copenhageni) detected in sick, apparently healthy dogs and in rodents is not contained in the vaccines used locally to protect dogs against canine leptospirosis.