Development, validation and testing costs of an in-house real-time PCR assay for the detection of Chlamydia trachomatis.

PURPOSE: To improve the screening of Chlamydia trachomatis(C. trachomatis) in Brazil, an accurate and affordable method is needed. The objective of this study was to develop and assess the performance and costs of a new in-house real-time PCR (qPCR) assay for the diagnosis of C. trachomatis infection. METHODOLOGY: Asymptomatic women aged 14-25 years who attended primary health services in Manaus, Brazil, were screened for C. trachomatis using the Digene Hybrid Capture II CT-ID (HCII CT-ID) DNA test. A subset of cervical specimens were tested using an in-house qPCR and a commercial qPCR, ArtusC. trachomatis Plus RG PCR 96 CE (Artus qPCR) kit, as a reference test. A primer/probe based on the sequence of cryptic plasmid (CP) was designed. An economic evaluation was conducted from the provider's perspective. RESULTS: The primers were considered specific for C. trachomatis because they did not amplify any product from non-sexually transmitted bacterial species tested. Overall, 292 specimens were tested by both the commercial kit (Artus qPCR) and the in-house qPCR. Of those, one resulted in no amplification and was excluded from the analysis. The sensitivity, specificity, and positive and negative predictive values of the in-house qPCR were 99.5 % [95 % confidence interval (CI): 97.1-100], 95.1 % (95 % CI: 89-98.4), 97.4 % (95 % CI: 94-99.1) and 99.0 % (95 % CI: 94.5-100), respectively. The cost per case of C. trachomatis was £0.44 ($0.55) for HCII CT-ID, £1.16 ($1.45) for Artus qPCR and £1.06 ($1.33) for in-house qPCR. CONCLUSION: We have standardized an in-house qPCR to detect cervical C. trachomatis targeting CP. The in-house qPCR showed excellent accuracy and was more affordable than the commercial qPCR kit.

Evaluation of screening for Chlamydia trachomatis among young women in primary health care services in Manaus, Amazonas State, Brazil.

Screening for Chlamydia trachomatis is not routinely offered to young asymptomatic women in Brazil. This study evaluated the performance, usefulness, and operational suitability of the Digene Hybrid Capture II (HCII) CT-ID DNA-test as an opportunistic screening tool to detect C. trachomatis in the public health system in Manaus, Amazonas State. Women aged 14-25 years who attended primary health care services were interviewed and one cervical specimen was collected during cytological screening. The HCII CT test was evaluated for its ability to detect the presence of C. trachomatis and against real-time PCR (q-PCR) in a subset of samples. Operational performance was assessed through interviews with providers and patients. Overall, 1,187 women were screened, and 1,169 had a HCII CT-ID test result (292 of these were also tested by q-PCR). Of those, 13.1% (n = 153) were positive. The sensitivity, specificity, positive and negative predictive values of HCII CT were 72.3% (95%CI: 65.4-78.6), 91.3% (95%CI: 84.1-95.9), 93.8% (95%CI: 88.5-97.1), and 64.4% (95%CI: 56.0-72.1), respectively. Sample collection caused discomfort in 19.7% of women. Among health professionals (n = 52), the main barriers reported included positive cases who did not return for results (56.4%), unwillingness to screen without an appointment (45.1%), and increase in their workload (38.8%). HCII CT-ID identified a high proportion of C. trachomatis cases among young women in Manaus. However, its moderate sensitivity limits its use as an opportunistic screening tool in primary health care settings in Manaus. Screening was well accepted although the barriers we identified, especially among health professionals, challenge screening detection and treatment efforts.

Evaluation of screening for Chlamydia trachomatis among young women in primary health care services in Manaus, Amazonas State, Brazil / Avaliação de rastreamento de Chlamydia trachomatis em mulheres jovens em serviços de atenção primaria de Manaus, Amazonas, Brasil / Evaluación de los exámenes de control de Chlamydia trachomatis entre mujeres jóvenes en los servicios de salud de atención primaria en Manaus, Amazonas, Brasil

Abstract: Screening for Chlamydia trachomatis is not routinely offered to young asymptomatic women in Brazil. This study evaluated the performance, usefulness, and operational suitability of the Digene Hybrid Capture II (HCII) CT-ID DNA-test as an opportunistic screening tool to detect C. trachomatis in the public health system in Manaus, Amazonas State. Women aged 14-25 years who attended primary health care services were interviewed and one cervical specimen was collected during cytological screening. The HCII CT test was evaluated for its ability to detect the presence of C. trachomatis and against real-time PCR (q-PCR) in a subset of samples. Operational performance was assessed through interviews with providers and patients. Overall, 1,187 women were screened, and 1,169 had a HCII CT-ID test result (292 of these were also tested by q-PCR). Of those, 13.1% (n = 153) were positive. The sensitivity, specificity, positive and negative predictive values of HCII CT were 72.3% (95%CI: 65.4-78.6), 91.3% (95%CI: 84.1-95.9), 93.8% (95%CI: 88.5-97.1), and 64.4% (95%CI: 56.0-72.1), respectively. Sample collection caused discomfort in 19.7% of women. Among health professionals (n = 52), the main barriers reported included positive cases who did not return for results (56.4%), unwillingness to screen without an appointment (45.1%), and increase in their workload (38.8%). HCII CT-ID identified a high proportion of C. trachomatis cases among young women in Manaus. However, its moderate sensitivity limits its use as an opportunistic screening tool in primary health care settings in Manaus. Screening was well accepted although the barriers we identified, especially among health professionals, challenge screening detection and treatment efforts.

Resumo: O rastreamento de Chlamydia trachomatis não é feito de rotina em mulheres jovens assintomáticas no Brasil. O estudo avaliou o desempenho, utilidade e adequação operacional do teste de DNA Digene Hybrid Capture II (HCII) CT-ID como ferramenta de rastreamento oportunista para detectar C. trachomatis no sistema público de saúde em Manaus, Amazonas. Mulheres entre 14 e 25 anos de idade que frequentavam serviços de atenção básica foram entrevistadas, com a coleta de uma amostra cervicouterina durante o rastreamento citológico. O teste HCII CT foi avaliado em relação à capacidade de detectar a presença de C. trachomatis, e comparado à PCR em tempo real (q-PCR) em um sub-conjunto de amostras. O desempenho operacional foi avaliado através de entrevistas com profissionais e pacientes. Foram examinadas 1.187 mulheres, das quais 1.169 tiveram um resultado de teste HCII CT-ID (destas, 292 foram testadas também com q-PCR). Um total de 153 mulheres (13,1%) testaram positivas para C. trachomatis. A sensibilidade, especificidade e valores preditivos positivo e negativo do HCII CT foram 72,3% (IC95%: 65,4-78,6), 91,3% (IC95%: 84,1-95,9), 93,8% (IC95%: 88,5-97,1) e 64,4% (IC95%: 56,0-72,1), respectivamente. A coleta de amostras provocou desconforto em 19,7% das mulheres. As principais barreiras relatadas pelos profissionais de saúde (n = 52) eram casos positivos que não retornavam para os resultados (56,4%), falta de disponibilidade de realizar o rastreamento sem consulta agendada (45,1%) e aumento da carga de trabalho (38,8%). O HCII CT-ID identificou alta prevalência de C. trachomatis em mulheres jovens de Manaus. Entretanto, a sensibilidade moderada limita o uso como ferramenta de rastreamento oportunista em serviços de atenção básica naquela cidade. O rastreamento era bem-recebido, mas as barreiras identificadas, principalmente entre profissionais de saúde, limitam a detecção através do rastreamento e as iniciativas de tratamento.

Resumen: Los exámenes de control de Chlamydia trachomatis no se ofrecen habitualmente a las mujeres jóvenes asintomáticas en Brasil. Este estudio evaluó los resultados, utilidad e idoneidad operativa del test Digene Hybrid Capture II (HCII) CT-ID DNA como una herramienta de examen apropiada para detectar la C. trachomatis en el sistema de salud público de Manaus, Amazonas. Las mujeres con una edad comprendida entre los 14-25 años que asistieron a un centro de atención primaria fueron entrevistadas, y se recogió una muestra cervical durante el examen citológico. Se evaluó el test HCII CT, debido a su habilidad para detectar la presencia de C. trachomatis, frente al realtime PCR (q-PCR) en un subconjunto de muestras. El resultado operativo fue evaluado mediante entrevistas con proveedores y pacientes. Globalmente, se examinaron a 1.187 mujeres, y 1.169 de ellas contaban con los resultados de la prueba HCII CT-ID (a 292 de las cuales también se les aplicó el test q-PCR). Entre ellas, un 13,1% (n = 153) eran positivo. La sensibilidad, especificidad, los valores predictivos positivos y negativos del HCII CT fueron 72,3% (IC95%: 65,4-78,6), 91,3% (IC95%: 84,1-95,9), 93,8% (IC95%: 88,5-97,1), y 64,4% (IC95%: 56,0-72,1), respectivamente. La toma de muestras resultó incómoda en un 19,7% de las mujeres. Entre los profesionales de la salud (n = 52), las barreras principales informadas incluyeron casos positivos que no volvieron a recoger los resultados (56,4%), reticencia a realizarse el examen sin cita previa (45,1%), e incremento en su carga laboral (38,8%). El HCII CT-ID identificó un alto porcentaje de casos de C. trachomatis entre mujeres jóvenes en Manaus. No obstante, su moderada sensibilidad limita su uso como una herramienta idónea en los centros de atención primaria en Manaus. El examen fue bien aceptado, pese a que identificamos obstáculos, especialmente entre los profesionales de salud, lo que supone un desafío para la detección de la enfermedad que requiere esfuerzos para su tratamiento.