Prevalence of Methicillin Resistant Staphylococcus aureus(MRSA) in pigs and workers at abattoirs in Trinidad and Tobago

Introduction: Methicillin resistant Staphylococcus aureus (MRSA), a major cause of zoonotic infections, has emerged globally in livestock, particularly pigs. People with occupational contact with food producing animals are at high risk of colonization. The aim of this study was to determine the prevalence of MRSA in pigs and abattoir workers throughout Trinidad and Tobago as well as their resistance to other antimicrobial agents. Methodology: Nasal and skin behind the ear swabs from pigs and nasal swabs from humans were enriched in Mueller Hinton broth with 6.5% sodium chloride, followed by phenol red mannitol broth with 75 mg/L aztreonam and 5 mg/L ceftizoxime. The enriched sample was then plated on both CHROMagar MRSA and Brilliance MRSA. All incubation was at 37ºC for approximately 24 h. Suspect MRSA isolates were confirmed as MRSA using the Penicillin-Binding Protein (PBP2a) test kit and polymerase chain reaction (PCR) to detect the mecA gene. Resistance of the S. aureus and MRSA isolates to 16 antimicrobial agents was determined using the disc diffusion method. Results: Of the 929 pigs and 44 humans sampled, MRSA strains were isolated at a frequency of 0.9% (8/929) and 2.3% (1/44) respectively. All isolates exhibited resistance to one or more of the 16 antimicrobial agents. Conclusions: The study demonstrated that pigs and workers at slaughter houses in Trinidad and Tobago harbour multidrug resistance S. aureus and MRSA. This is of public health significance as occupational exposure of humans can lead to an increased risk of infection and therapeutic failure.

Molecular analysis of Salmonella isolates from poultry by pulsed-field gel electrophoresis

Objective: The study was conducted to determine geneticrelatedness of Salmonella serotypes by pulsed field gel electrophoresis (PFGE). Design and Methodology: A total of 1503 caecal samples of freshly slaughtered poultry were randomly collected from 'pluck shops' across the country. The samples were screened for Salmonella by biochemical, serological and molecular methods. The Salmonella serotypes were analyzed for genetic relatedness for phenotypic antimicrobial resistance, resistance and virulence gene profiles by PFGE generated by digestion with XbaI. Results: Ten different serotypes were detected from all 91 Salmonella isolates. PFGE fingerprinting profiles showed that the Salmonella serotypes in general, were genetically diverse with the detection of a total of 20 PFGE groups. The antibiograms of the isolates were also clearly very variable, which suggest that genotypic antimicrobial resistance may not relate to the phenotypic antibiograms in dendrograms, except for qnrB gene. Results demonstrated a varied spectrum of antimicrobial resistance and PFGE patterns among Salmonella isolates and signify the importance of sustained surveillance of foodborne pathogens in retail poultry pluck shops. Conclusions: The findings provide evidence that poultry from pluck shops are colonized by pathogenic Salmonella harboring antimicrobial resistance genes. The study also reported for the first time in Trinidad, molecular characterization of Salmonella isolates from poultry regarding the relatedness of antibiograms, possession of resistance and virulence genes using their PFGE profiles. The epidemiological surveillance of these serotypes would be necessary to evaluate their possible impact on human health in the country and possibly in the Caribbean region.

Prevalence of Salmonella species in broilers during slaughtering by processing plants in Trinidad using three isolation methods

Objective: To determine the prevalence of Salmonella species during slaughtering and dressing of broiler chickens at four poultry processing plants in Trinidad using three isolation methods. Design and Methodology: In this cross-sectional study, a total of 396 samples were collected from all four commercial poultry processing plants in Trinidad. Samples collected comprised swabs of cloacae pre-slaughter, pre evisceration and post evisceration carcasses; immersion chiller water, neck skins, whole carcasses and chicken parts (final product). Isolation and identification of Salmonella spp. were performed using standard bacteriological techniques (whole carcass enrichment, whole carcass rinse and neck skin methods). Results: The overall prevalence of Salmonella spp. was 27.5% (109/396). The prevalence of Salmonella spp. was 2.2% (2/90), 55.6% (25/45), 37.8% (17/45), 27.8% (25/90), 5.6% (2/36), 44.4% (20/45) and 40.0% (18/45) for cloacal swabs, preevisceration carcasses, post evisceration carcass swabs, neck skins, immersion chiller water, whole carcass and chicken parts respectively (p<0.001). Salmonella was isolated from 52.3% (46/88), 19.3% (34/176), 11.4% (5/44) and 27.3% (24/88) of the samples from Plant A, B, C and D respectively (p<0.001). Overall, Salmonella was detected in 27.2% (49/180), 27.8% (25/90) and 39.4% (71/180) carcasses by whole carcass rinse, neck skin method and whole carcass enrichment method respectively (p= 0.028). Conclusion: Data from the study indicate the extent of contamination by Salmonella spp. throughout the various stages of broiler processing at the four plants studied and, of significance is the risk of salmonellosis posed to consumers of contaminated, undercooked chicken sold to retail outlets by these processing plants in the country.

Cytokines changes in beagle dogs vaccinated and challenged with virulent Leptospira strains

Objective: To determine the immune response of dogs by measuring the levels of cytokines tumour necrosis factor (TNF) α, interleukin (IL)-4 and interferon (IFN) γ pre- and post-vaccination with a locally produced killed whole-celled Leptospira vaccine. Design and Methodology: Three separate vaccine-challenge experiments involving 21 beagle dogs were conducted. Study 1 (duration of immunity), used 6 vaccinated and 3 non-vaccinated (control) dogs. Vaccination was done at 12 and 16 weeks of age and challenged at 12 months of age with 1-2.5 x 108 live Leptospira. Study 2 (onset of immunity) also contained the same number of dogs as study 1. Vaccination was done at 12 and 16 weeks of age and challenged at 18 weeks of age. Study 3 (onset of immunity study), as study 2, used 4 vaccinated and two control dogs but challenged with 1-2.5 X 109 live Leptospira. Blood samples were collected to measure the levels of TNF α, IL-4 and IFN γ in dogs 2 days pre-challenge and daily thereafter until day 7 post-challenge. Results: For cytokine TNF α, pre-challenge levels for Study 1, 2 and 3 were 0.0000, 0.0755 and 0.0705 pg/ml which increased to a maximum post-challenge level of 49.05 pg/ml, 0.47 pg/ml and 1.667pg/ml respectively. For cytokine IL-4 and IFN γ the level increased from 0.00 pg/ml to a maximum post-challenge level of 52.67 pg/ml, 243.34 pg/ml and 989.14 pg/ml; and 281.91 pg/ml, 1223.85 pg/ ml and 1778.95 pg/ml respectively. Conclusion: The locally produced Leptospira vaccine induced immune response post-challenge with live Leptospira.

Prevention of severe clinical signs and pathological lesions of leptospirosis in experimentally challenged dogs

Objective: To prevent severe clinical and pathological findings of leptospirosis in dogs vaccinated against L. interrogans serovar Copenhageni. Design and Methodology: Two vaccination-challenge experiments involving 22 dogs were performed using a vaccine prepared from formalin-killed cultures of L. interrogans serovar Copenhageni. The dogs were challenged by administering a suspension of 1 x 109 of a virulent strain of serovar Copenhageni (8 mL) at 2 weeks (Study 1: Onset of immunity) and 14 months (Study 2: Duration of immunity) after primary and secondary vaccinations. Each dog was observed for clinical signs of leptospirosis for five weeks post-challenge (PC). Any dog which showed irreversible clinical signs of leptospirosis was humanely euthanized, and a necropsy performed. Results: One (20.0 %) vaccinated puppy in Study 1 showed mild clinical signs (PC) which lasted for one day. Five (100.0 %) non-vaccinated (controls) puppies exhibited irreversible signs of acute severe leptospirosis PC, as well as significant postmortem lesions consistent with leptospiral infection. In Study 2, no clinical signs were exhibited by the vaccinated group of dogs PC, while two (40.0 %) non-vaccinated dogs exhibited mild clinical signs for 2 to 3 days, after which they recovered. Conclusions: The vaccine was successful in protecting vaccinated dogs against acute leptospirosis 2 weeks and 14 months after a vaccination schedule of two doses of the bacterin (primary and booster doses), since all vaccinated dogs were clinically normal after challenge with a virulent inoculum of serovar Copenhageni.

Serological evidence of widespread exposure of Grenada fruit bats to chikungunya virus.

Antibody detection against selected potentially zoonotic vector-borne alphaviruses and flaviviruses was conducted on sera from bats from all six parishes in Grenada, West Indies. Sera were tested for (i) antibodies to flaviviruses West Nile virus, St. Louis encephalitis virus, Ilhéus virus, Bussuquara virus (BSQV), Rio Bravo virus and all four serotypes of dengue virus (DENV) by plaque reduction neutralization test (PRNT); (ii) antibodies to alphaviruses western equine encephalitis virus, Venezuelan equine encephalitis virus and eastern equine encephalitis virus by epitope-blocking enzyme-linked immunosorbent assay (ELISA); and (iii) antibodies to the alphavirus chikungunya (CHIKV) by PRNT. Two species of fruit bats were sampled, Artibeus jamaicensis and Artibeus lituratus, all roosting in or within 1,000 m of human settlements. Fifteen (36%) of the 42 bats tested for neutralizing antibodies to CHIKV were positive. The CHIKV-seropositive bats lived in localities spanning five of the six parishes. All 43 bats tested for epitope-blocking ELISA antibody to the other alphaviruses were negative, except one positive for Venezuelan equine encephalitis virus. All 50 bats tested for neutralizing antibody to flaviviruses were negative, except one that had a BSQV PRNT80 titre of 20. The CHIKV serology results indicate that bats living close to and within human settlements were exposed to CHIKV in multiple locations. Importantly, bats for this study were trapped a year after the introduction and peak of the human CHIKV epidemic in Grenada. Thus, our data indicate that bats were exposed to CHIKV possibly during a time of marked decline in human cases.

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 selected alphaviruses and flaviviruses in bats in Trinidad.

A serosurvey of antibodies against selected flaviviruses and alphaviruses in 384 bats (representing 10 genera and 14 species) was conducted in the Caribbean island of Trinidad. Sera were analysed using epitope-blocking enzyme-linked immunosorbent assays (ELISAs) specific for antibodies against West Nile virus (WNV), Venezuelan equine encephalitis virus (VEEV) and eastern equine encephalitis virus (EEEV), all of which are zoonotic viruses of public health significance in the region. Overall, the ELISAs resulted in the detection of VEEV-specific antibodies in 11 (2.9%) of 384 bats. Antibodies to WNV and EEEV were not detected in any sera. Of the 384 sera, 308 were also screened using hemagglutination inhibition assay (HIA) for antibodies to the aforementioned viruses as well as St. Louis encephalitis virus (SLEV; which also causes epidemic disease in humans), Rio Bravo virus (RBV), Tamana bat virus (TABV) and western equine encephalitis virus (WEEV). Using this approach, antibodies to TABV and RBV were detected in 47 (15.3%) and 3 (1.0%) bats, respectively. HIA results also suggest the presence of antibodies to an undetermined flavivirus(es) in 8 (2.6%) bats. Seropositivity for TABV was significantly (P<0.05; χ2) associated with bat species, location and feeding preference, and for VEEV with roost type and location. Differences in prevalence rates between urban and rural locations were statistically significant (P<0.05; χ2) for TABV only. None of the aforementioned factors was significantly associated with RBV seropositivity rates.

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.

Calabash pregnancy: a malingering response to infertility complicated by domestic violence.

This is a case report of a 20-year old para 0+0 who presented with an 11-month pregnancy. On evaluation, the pregnancy was found to be a fake made-up 'calabash pregnancy'. There were no pregnancy symptoms and she had just menstruated three weeks prior to presentation. This was a deliberate event in response to delayed pregnancy attainment complicated by domestic violence. Domestic violence was in the form of verbal and physical abuse and later was on a monthly basis precipitated by onset of her menstrual flow. The patient's age, monogamous union and the fact that she is an orphan made her vulnerable to domestic violence.

Efficacy of commonly used anthelmintics: first report of multiple drug resistance in gastrointestinal nematodes of sheep in Trinidad.

In Trinidad, small ruminant farms are semi-intensively managed under tropical conditions which support the development and survival of the infective stages of the helminths. Local farmers use anthelmintics to control gastrointestinal nematodes frequently. Frequent use of anthelmintics has the potential to select for populations of nematodes resistance to those chemicals. Hence, an attempt was made to study the efficacy of commonly used drugs on gastrointestinal nematodes of sheep. Three farms situated in different counties in Trinidad were selected. Sheep aged 6-15 months and not treated with anthelmintics for a minimum of six months previous and with faecal egg count (FEC)>150 eggs per gram were selected for study. They were allocated into 5 groups, each consisting 10 animals. The Group TA animals were treated once with albendazole (5mg/kg. b.wt.), group TF with fenbendazole (5mg/kg.b.wt.), group TI animals with ivermectin (200 µg/kg b.wt.), group TL with levamisol (7.5mg/kg b.wt.). The group NTC animals were not given any drug and served as control. The number of nematode eggs per gram of faeces from each animal was determined before treatment and at 14 days after treatment. The anthelmintic susceptibility to different drugs was detected by FECRT (in vivo) with EPG recorded at 14 day post-treatment. The data analysis using FECRT revealed that efficacy of albendazole (46-62%), fenbendazole (44-61%) and levamisol (53-81%) were reduced compared to ivermectin (95-97%). An attempt has also been made to find a suitable method for calculation of FECR (%).

Occurrence and genetic relatedness of Listeria spp. in two brands of locally processed ready-to-eat meats in Trinidad.

Contamination of locally produced, ready-to-eat meats by Listeria spp. has been previously reported at one processing plant in Trinidad. However, the status of this pathogen in locally produced products sold at retail outlets is unknown. This study was conducted to establish whether there is a risk to consumers of locally processed meats caused by the presence of Listeria spp., and whether a link exists between the presence of the pathogen in retail products and the manufacturing plant of one brand (B). Four hundred and eighty ready-to-eat meat products of two popular local brands (A and B) were collected from retail outlets and analysed for the presence of Listeria spp. together with food samples and surfaces from one manufacturing plant (B). Eighty-eight of the retail products (18·3%) were contaminated with Listeria spp., of which, 52·3% were L. innocua, 44·3% were L. monocytogenes and 3·4% belonged to the L. seeligeri-L. welshimeri-L. ivanovii (Siwi) group. L. innocua was found in 15 in-process food samples and on three surfaces of equipment at plant B. Four in-process food samples were also contaminated with Siwi isolates. Repetitive extragenic palindromic PCR DNA fingerprinting showed a possible association between strains of different Listeria spp. and brand as well as with manufacturing plant B.

Seroprevalence of toxoplasmosis, leptospirosis and brucellosis in sugarcane field-workers in Trinidad and Tobago.

Sugarcane field-workers, like rice field-workers, livestock farmers and abattoir workers are known to be occupationally exposed to zoonotic agents. The study determined the seroprevalence of immunoglobulins to Toxoplasma gondii (IgM), Leptospira spp (IgM) and Brucella abortus (IgG) in sugarcane field-workers across weighing stations in the island of Trinidad. In addition, the association of risk factors to infections by the three zoonoses was investigated. Blood samples were collected from consenting apparently healthy sugarcane field-workers across the island of Trinidad. Current/acute infection in individuals was determined in the sera of individuals using the enzyme immunoassay (EIA) for T gondii IgM antibodies, enzyme-linked immunosorbent assay (ELISA) for Leptospira spp IgM immunoglobulins and both buffered plate agglutination test (BPAT) and competitive ELISA for B abortus IgG antibodies. The seroprevalence of IgM immunoglobulins to T gondii was 15.7% (64 of 407) and to Leptospira spp was 0.7% (5 of 704) and the difference was statistically significant (p 0 < 0.05; chi2). All 704 samples tested for B abortus IgG immunoglobulins were negative. All risk factors (age, gender race and type of work done) were not statistically significantly (p > 0.05; chi2) associated with infections by T gondii and Leptospira spp. It was concluded that sugarcane field-workers in Trinidad were at high risk of acute toxoplasmosis and, to a lesser extent, to leptospirosis. The fact that the four risk factors studied were not significantly associated with T gondii and Leptospira spp infections suggests that they may not be important in the epidemiology of both diseases in the population studied.

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.

Seroprevalence of toxoplasmosis, leptospirosis and brucellosis in sugarcane fieldworkers in Trinidad and Tobago / Seroprevalencia de la toxoplasmosis, la leptospirosis y la brucelosis en los trabajadores de las plantaciones de caña de azúcar en Trinidad y Tobago

Sugarcane field-workers, like rice field-workers, livestock farmers and abattoir workers are known to be occupationally exposed to zoonotic agents. The study determined the seroprevalence of immunoglobulins to Toxoplasma gondii (IgM), Leptospira spp (IgM) and Brucella abortus (IgG) in sugarcane field-workers across weighing stations in the island of Trinidad. In addition, the association of risk factors to infections by the three zoonoses was investigated. Blood samples were collected from consenting apparently healthy sugarcane field-workers across the island of Trinidad. Current/acute infection in individuals was determined in the sera of individuals using the enzyme immunoassay (EIA) for T gondii IgM antibodies, enzyme-linked immunosorbent assay (ELISA) for Leptospira spp IgM immunoglobulins and both buffered plate agglutination test (BPAT) and competitive ELISA for B abortus IgG antibodies. The seroprevalence of IgM immunoglobulins to T gondii was 15.7% (64 of 407) and to Leptospira spp was 0.7% (5 of 704) and the difference was statistically significant (p 0 < 0.05; χ2). All 704 samples tested for B abortus IgG immunoglobulins were negative. All risk factors (age, gender, race and type of work done) were not statistically significantly (p > 0.05; χ2) associated with infections by T gondii and Leptospira spp. It was concluded that sugarcane field-workers in Trinidad were at high risk of acute toxoplasmosis and, to a lesser extent, to leptospirosis. The fact that the four risk factors studied were not significantly associated with T gondiiand Leptospira spp infections suggests that they may not be important in the epidemiology of both diseases in the population studied.

Se sabe que los trabajadores de las plantaciones de caña de azúcar - al igual que los trabajadores de los campos de arroz, la ganadería y los mataderos - se hallan expuestos a agentes zoonóticos debido a su ocupación. El estudio determinó la seroprevalencia de las inmunoglobulinas en relación con Toxoplasma gondii (IgM), Leptospira spp (IgM) y Brucella abortus (IgG) en los trabajadores cañeros a lo largo de las estaciones de pesaje en la isla de Trinidad. Además, se investigó la asociación de factores de riesgo de infecciones por las tres formas de zoonosis. Se obtuvieron muestras de sangre a lo largo de la isla de Trinidad, tomadas de trabajadores cañeros de apariencia saludable, que dieron su consentimiento. La infección aguda presente en los individuos, fue determinada en sus sueros mediante el inmunoensayo enzimático (IEE) para anticuerpos de T gondii IgM, el ensayo inmunosorbente vinculado a enzimas (ELISA) para inmunoglobulinas frente a Leptospira spp IgM, y la prueba de aglutinación tamponada en placa (BPAT) así como el ELISA competitivo para anticuerpos de B abortus IgG. Palabras claves: toxoplasmosis, leptospirosis, brucelosis, trabajadores cañeros, Trinidad. La seroprevalencia de inmunoglobulinas IgM para T gondii fue de 15,7% (64 de 407) en tanto que para la Leptospira spp fue 0,7% (5 de 704). La diferencia fue estadísticamente significativa (p 0 < 0.05; c²). Las 704 muestras sometidas a la prueba de inmunoglobulinas para B abortus IgG, fueron negativas. Los factores de riesgo (edad, género, raza y tipo de trabajo realizado) no estuvieron significativamente asociados (p > 0.05; c²) de manera estadística con las infecciones por T gondii y Leptospira spp Se llegó a la conclusión de que los trabajadores cañeros de Trinidad presentaban un alto riesgo de toxoplasmosis aguda y, en menor medida, de leptospirosis. El hecho de que los cuatro factores de riesgo estudiados no estaban significativamente asociadas con T gondiiy a infecciones de Leptospira spp, sugiere que puede que no sean importantes en la epidemiología de ambas enfermedades en la población estudiada.

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.

Prevalence of bacterial pathogens and their anti-microbial resistance in Tilapia and their pond water in Trinidad.

In Trinidad, Tilapia (Oreonchromis spp.) is one of the most important fresh water food fish and the number of farms has been increasing annually. A study was conducted in the local tilapia industry to determine the microbial quality of pond water, prevalence of bacterial pathogens and their anti-microbial resistance using the disk diffusion method. Seventy-five apparently healthy fish and 15 pond water samples from three of the four commercial tilapia fish farms in the country were processed. The 202 bacterial isolates recovered from fish slurry and 88 from water, belonged to 13 and 16 genera respectively. The predominant bacteria from fish slurry were Pseudomonas spp. (60.0%), Aeromonas spp. (44.0%), Plesiomonas (41.3%) and Chromobacterium (36.0%) (P < 0.05; chi(2)) compared with isolates from pond water where Bacillus spp. (80.0%), Staphylococcus spp., Alcaligenes spp. and Aeromonas spp. (60.0%) were most prevalent (P < 0.05; chi(2)). Using eight anti-microbial agents, to test bacteria from five genera (Aeromonas, Chromobacterium, Enterobacter, Plesiomonas and Pseudomonas), 168 (97.1%) of 173 bacterial isolates from fish slurry exhibited resistance to one or more anti-microbial agents compared with 47 (90.4%) of 52 from water (P > 0.05; chi(2)). Resistance was high to ampicillin, 90.2% (158 of 173), erythromycin, 66.5% (115 of 173) and oxytetracycline, 52.6%, (91 of 173) but relatively low to chloramphenicol, 9.8% (17 of 173) and sulphamethoxazole/trimethoprim, 6.4% (11 of 173) (P < 0.05; chi(2)). For pond water isolates, the frequency of resistance across bacterial genera ranged from 75% (nine of 12) for Chromobacter spp. to 100% found amongst Enterobacter spp. (six of six), Plesiomonas spp. (nine of nine) and Pseudomonas spp. (eight of eight) (P < 0.05; chi(2)). Resistance was generally high to ampicillin, 78.8% (41 of 52), erythromycin, 51.9% (27 of 52) and oxytetracycline, 34.5% (18 of 52) but low to sulphamethoxazole/trimethoprim, 7.7% (four of 52) and norfloxacin, 3.8% (two of 52) (P < 0.05; chi(2)). It was concluded that the rather high prevalence of bacterial pathogens in tilapia along with their high prevalence of resistance to anti-microbial agents might pose therapeutic problems as well as health risk to consumers. The microbial presence and their anti-microbial resistance in the tilapia industry are being reported for the first time in the country.

Microbial load and the prevalence of Escherichia coli, Salmonella spp. and Listeria spp. in Ready-to-Eat products in Trinidad.

This study was designed to determine the prevalence and microbial load of Listeria spp., Escherichia coli O157 and Salmonella spp. in ready-to-eat products in supermarkets across Trinidad. The microbial load was assessed using the total aerobic plate count (TAPC) per g/ml of foods and prevalence of Escherichia coli O157 and Salmonella spp. determined using conventional methods. For Listeria monocytogenes, immunomagnetic separation (IMS), TECRA (enzymelinked immunosorbent assay, ELISA) and conventional methods were used. The log10 mean ñ sd TAPC per g or ml was highest for vegetables (11.0ñ11.6), and lowest for seafood (5.2ñ5.7) (p < 0.05). The prevalence of L. monocytogenes was 1.7 per cent. Sixteen (4.5 per cent) of 153 samples yielded E. coli but all samples were negative for Salmonella spp. and E. coli O157. The high microbial load and isolation of L. monocytogenes and E. coli from popular RTE foods could pose a health risk to consumers in the country.

Prevalence of bacterial pathogens and their anti-microbial resistance in Tilapia and their pond water in Trinidad.

In Trinidad, Tilapia (Oreonchromis spp.) is one of the most important fresh water food fish and the number of farms has been increasing annually. A study was conducted in the local tilapia industry to determine the microbial quality of pond water, prevalence of bacterial pathogens and their anti-microbial resistance using the disk diffusion method. Seventy-five apparently healthy fish and 15 pond water samples from three of the four commercial tilapia fish farms in the country were processed. The 202 bacterial isolates recovered from fish slurry and 88 from water, belonged to 13 and 16 genera respectively. The predominant bacteria from fish slurry were Pseudomonas spp. (60.0 per cent), Aeromonas spp. (44.0 per cent), Plesiomonas (41.3 per cent) and Chromobacterium (36.0 per cent) (P < 0.05; chi(2)) compared with isolates from pond water where Bacillus spp. (80.0 per cent), Staphylococcus spp., Alcaligenes spp. and Aeromonas spp. (60.0 per cent) were most prevalent (P < 0.05; chi(2)). Using eight anti-microbial agents, to test bacteria from five genera (Aeromonas, Chromobacterium, Enterobacter, Plesiomonas and Pseudomonas), 168 (97.1 per cent) of 173 bacterial isolates from fish slurry exhibited resistance to one or more anti-microbial agents compared with 47 (90.4 per cent) of 52 from water (P > 0.05; chi(2)). Resistance was high to ampicillin, 90.2 per cent (158 of 173), erythromycin, 66.5 per cent (115 of 173) and oxytetracycline, 52.6 per cent, (91 of 173) but relatively low to chloramphenicol, 9.8 per cent (17 of 173) and sulphamethoxazole/trimethoprim, 6.4 per cent (11 of 173) (P < 0.05; chi(2)). For pond water isolates, the frequency of resistance across bacterial genera ranged from 75 per cent (nine of 12) for Chromobacter spp. to 100 per cent found amongst Enterobacter spp. (six of six), Plesiomonas spp. (nine of nine) and Pseudomonas spp. (eight of eight) (P < 0.05; chi(2))...