Comparison of polymerase chain reaction and bacterial culture for Salmonella detection in the Muscovy duck in Trinidad and Tobago / Comparación de la reacción en cadena de la polimerasa y el cultivo bacteriano como métodos de detección de Salmonella en patos criollos en Trinidad y Tobago

OBJECTIVES: The purpose of this study was to investigate the presence and serovar identity of Salmonella, at the national level, in farmed Muscovy ducks (Cairina moschata) in Trinidad and Tobago, and to compare the relative benefits of bacterial culture to those of polymerase chain reaction (PCR) for use in the routine detection and surveillance of Salmonella in these ducks. METHODS: From March-September 2003, 110 fecal samples were collected from 82 farms across the islands of Trinidad and Tobago. Salmonella was isolated from fresh and frozen samples and the serotype of each was determined through bacterial culture. An in-house, nested PCR that detects all pathogenic Salmonella species was utilized in analyzing the samples. RESULTS: Five samples were positive for Salmonella by bacterial culture, whereas 44 were positive by the nested PCR. Serovars isolated were Kiambu, Orion, Uganda, and two isolates from Group E1 whose H antigens could not be fully characterized. Of the samples, 87 (79 percent) gave equivalent PCR results for both enrichment broths-28 were positive for both and 59 were negative for both). However, 16 samples were positive for one broth, but not for the other, with the majority (14 of the 16) resulting positive for Selenite broth. PCR results for seven samples were inconclusive due to ambiguous band size or multiple bands near the expected band size. CONCLUSIONS: In Trinidad and Tobago, the Muscovy duck does not appear to be a significant source of S. typhimurium or S. enteritidis, but it does harbor other Salmonella species. In-house, nested PCR represents a simple, relatively inexpensive and potentially more sensitive method than bacterial culture for the routine surveillance of pathogenic Salmonella in the Muscovy duck.

OBJETIVOS: Investigar la presencia de Salmonella en patos criollos (Cairina moschata) criados en Trinidad y Tobago e identificar los serotipos circulantes en el país, así como comparar los beneficios relativos del cultivo bacteriano con respecto a la reacción en cadena de la polimerasa (RCP) en la detección y la vigilancia cotidianas de la Salmonella en estos patos. MÉTODOS: Entre marzo y septiembre de 2003 se tomaron 110 muestras de heces fecales de 82 granjas distribuidas por las islas de Trinidad y Tobago. Se aisló Salmonella de muestras frescas y congeladas y se determinaron los serotipos mediante el cultivo bacteriano. Se utilizó un sistema autóctono de RCP anidada que detecta todas las especies patógenas de Salmonella en las muestras. RESULTADOS: Cinco muestras resultaron positivas para Salmonella mediante el cultivo bacteriano, mientras que 44 fueron positivas mediante la RCP anidada. Se asilaron los serotipos Kiambu, Orion, Uganda y dos aislamientos del grupo E1, cuyos antígenos H no se pudieron caracterizar totalmente. Hubo coincidencia en 87 (79 por ciento) de las muestras analizadas por RCP en ambos caldos de enriquecimiento (28 positivas y 59 negativas). Sin embargo, 16 muestras positivas en un caldo resultaron negativas en el otro; la mayoría de ellas (14 de 16) resultaron positivas en caldo selenito. Siete muestras resultaron indefinidas mediante la RCP debido a tallas ambiguas de las bandas o a múltiples bandas cerca de la talla esperada. CONCLUSIONES: El pato criollo no parece ser una fuente importante de infección por S. typhimurium y S. enteritidis en Trinidad y Tobago, aunque hospeda otras especies de Salmonella. El sistema autóctono de RCP anidada constituye un método simple, relativamente económico y posiblemente más sensible que el cultivo bacteriano en la vigilancia cotidiana de especies patógenas de Salmonella en el pato criollo.

In-house polymerase chain reaction for affordable and sustainable Chlamydia trachomatis detection in Trinidad and Tobago.

OBJECTIVES: To provide a preliminary assessment of in-house polymerase chain reaction (PCR) as an alternative to the more costly commercial test for detection of asymptomatic infection by Chlamydia trachomatis and to provide much needed demographic data on infection indicators within the Trinidad and Tobago public health care system. METHODS: An inexpensive in-house nested-PCR with an Internal Amplification Control was used to detect C. trachomatis and Neisseria gonorrhoeae in urine samples collected from 273 apparently healthy, pregnant women from March-September 2004 in Trinidad, West Indies. Demographic information on participants was collected and subjected to statistical analyses. RESULTS: C. trachomatis was detected in 57/273 (21 per cent) samples, of which 5 (2 per cent) were also positive for N. gonorrhoeae. Infection correlated well with certain demographic parameters, with the highest incidence of C. trachomatis infection found among pregnant women that were single or of African descent. CONCLUSIONS: Given the lack of commercial tests in Trinidad, in-house PCR is an inexpensive alternative that can be used to detect asymptomatic infections of C. trachomatis and to provide demographic information needed for interventions by the public health care system.

In-house polymerase chain reaction for affordable and sustainable Chlamydia trachomatis detection in Trinidad and Tobago

OBJECTIVES: To provide a preliminary assessment of in-house polymerase chain reaction (PCR) as an alternative to the more costly commercial test for detection of asymptomatic infection by Chlamydia trachomatis and to provide much needed demographic data on infection indicators within the Trinidad and Tobago public health care system. METHODS: An inexpensive in-house nested-PCR with an Internal Amplification Control was used to detect C. trachomatis and Neisseria gonorrhoeae in urine samples collected from 273 apparently healthy, pregnant women from March-September 2004 in Trinidad, West Indies. Demographic information on participants was collected and subjected to statistical analyses. RESULTS: C. trachomatis was detected in 57/273 (21 percent) samples, of which 5 (2 percent) were also positive for N. gonorrhoeae. Infection correlated well with certain demographic parameters, with the highest incidence of C. trachomatis infection found among pregnant women that were single or of African descent. CONCLUSIONS: Given the lack of commercial tests in Trinidad, in-house PCR is an inexpensive alternative that can be used to detect asymptomatic infections of C. trachomatis and to provide demographic information needed for interventions by the public health care system.

OBJETIVOS: Hacer una evaluación preliminar de un sistema autóctono para la detección de la infección asintomática por Chlamydia trachomatis mediante la reacción en cadena de la polimerasa (RCP), como alternativa a los costosos sistemas comerciales, y ofrecer datos demográficos muy necesarios relacionados con los indicadores de esta infección en el sistema de salud pública de Trinidad y Tobago. MÉTODOS: Se empleó un sistema autóctono y económico de RCP anidada con control interno de la amplificación para la detección de C. trachomatis y Neisseria gonorrhoeae en muestras de orina de 273 mujeres embarazadas asintomáticas, entre marzo y septiembre de 2004 en Trinidad y Tobago, Indias Occidentales. Se obtuvo la información demográfica de las participantes y se sometió a análisis estadístico. RESULTADOS: Se detectó C. trachomatis en 57/273 (21 por ciento) muestras, de las cuales 5 (2 por ciento) fueron también positivas para N. gonorrhoeae. La infección se correlacionó bien con algunos parámetros demográficos; la mayor incidencia de la infección por C. trachomatis se observó en las mujeres embarazadas solteras o de ascendencia africana. CONCLUSIONES: Debido al déficit de sistemas de diagnóstico comerciales en Trinidad, la RCP autóctona es una alternativa económica que puede emplearse para detectar la infección asintomática por C. trachomatis y obtener la información demográfica necesaria para que el sistema de salud pública implemente intervenciones.

A nested-PCR with an Internal Amplification Control for the detection and differentiation of Bartonella henselae and B. clarridgeiae: an examination of cats in Trinidad

BACKGROUND: Bartonella species are bacterial blood parasites of animals capable of causing disease in both animals and man. Cat-Scratch Disease (CSD) in humans is caused mainly by Bartonella henselae and is acquired from the cat, which serves as a reservoir for the bacteria. A second species, B. clarridgeiae is also implicated in the disease. Diagnosis of Bartonellosis by culture requires a week or more of incubation on enriched media containing blood, and recovery is often complicated by faster growing contaminating bacteria and fungi. PCR has been explored as an alternative to culture for both the detection and species identification of Bartonella, however sensitivity problems have been reported and false negative reactions due to blood inhibitors have not generally been addressed in test design. METHODS: A novel, nested-PCR was designed for the detection of Bartonella henselae and B. clarridgeiae based on the strategy of targeting species-specific size differences in the 16S-23S rDNA intergenic regions. An Internal Amplification Control was used for detecting PCR inhibition. The nested-PCR was utilized in a study on 103 blood samples from pet and stray cats in Trinidad. RESULTS: None of the samples were positive by primary PCR, but the Nested-PCR detected Bartonella in 32/103 (31%) cats where 16 were infected with only B. henselae, 13 with only B. clarridgeiae and 3 with both species. Of 22 stray cats housed at an animal shelter, 13 (59%) were positive for either or both species, supporting the reported increased incidence of Bartonella among feral cats. CONCLUSION: The usefulness of a single PCR for the detection of Bartonella henselae and B. clarridgeiae in the blood of cats is questionable. A nested-PCR offers increased sensitivity over a primary PCR and should be evaluated with currently used methods for the routine detection and speciation of Bartonella henselae and B. clarridgeiae. In Trinidad, B. henselae and B. clarridgeiae are the predominant species in cats and infection appears highest with stray cats, however B. clarridgeiae may be present at levels similar to that of B. henselae in the pet population.

Molecular characterization of rabies virus isolates from Trinidad

Bovine rabies continues to be a serious problem facing the cattle industry in South and Central America. Although Trinidad played an important role in originally demonstrating the link between bats and bovine rabies, relatively little is known about rabies in Trinidad, an island 7miles off the coast of Venezuela. In order to obtain a more complete understanding of bovine rabies in the region, we report herein on a study undertaken in Trinidad to characterize isolates of rabies virus obtained from infected cattle. A portion of the nucleotide sequence of the nucleoprotein gene from six rabies virus isolates collected from bovine rabies from the years 1997, 1998 and 2000 was determined and compared both to themselves and the nucleotide sequence of other South American isolates. Results indicate that there are at least two independently evolving variants of rabies virus in Trinidad. The nucleotide sequence of either variant failed to match completely the sequence of South American isolates. However, the lack of South American isolates from coastal regions facing Trinidad leaves undetermined the question of South American influence on rabies in Trinidad. The results of this study helps complete the picture of bovine rabies in the South American region and provide basic information required locally for the creation of an effective rabies control and eradication strategy.