ABSTRACT
@#Data on the accuracy of Xpert® MTB/RIF (Xpert) assay in detecting TB in lymph node aspirates in Papua New Guinea (PNG) is scanty. This study evaluated Xpert performance in diagnosing tuberculous lymphadenitis (TBLN) using lymph node needle aspirates at the Port Moresby General Hospital (PMGH). The objective of the study was to compare Xpert accuracy to acid fast bacilli (AFB) microscopy, cytomorphology, a composite reference test (CRS) and culture. A total of 107 eligible subjects were recruited out of 1080 clinic attendees. Results showed Xpert detected significantly more cases of TBLN than AFB microscopy (66 vs 35; p=0.001). Compared to AFB microscopy Xpert had a sensitivity of 45.4% (95% CI 33.1-58.1), specificity of 87.8% (95% CI 73.8-95.9), positive predictive value (PPV) of 85.7% (95% CI 71.6-93.4) and negative predictive value (NPV) of 50.0%% (95% CI 43.8-56.1). There was no difference between Xpert and cytomorphology (66 vs 60; p=0.5). Compared to cytomorphology Xpert had a sensitivity of 71.6% (95% CI 58.5-82.5), specificity of 51.1% (95% CI 35.7-66.3), PPV of 66.1% (95% CI 58.2-73.2) and NPV of 57.5% (95% CI 45.2-68.9). There was no difference between Xpert and CRS (66 vs 71; p=0.6). Compared to CRS Xpert had a sensitivity of 76.0% (95% CI 64.4- 85.3), specificity of 66.6% (95% CI 49.0-81.4), PPV of 81.8% (95% CI 73.5-87.9) and NPV of 58.4% (95% CI 46.7-69.4). Culture was completed on 24 subjects with positive isolates in 14 giving a culture yield of 58.3%. Of the 24 subjects, Xpert was positive in 21 subjects. There was no difference between Xpert and culture (21 vs 14; p=0.8). Compared to culture Xpert had a sensitivity of 100.0% (95% CI 76.8-100.0), specificity of 30.0% (95% CI 6.6-65.2), PPV of 66.6% (95% CI 57.1-75) and NPV of 100.0%. The results suggest Xpert is more sensitive than AFB microscopy but comparable to cytomorphology and CRS for TBLN diagnosis in the PNG context. Xpert can be used for diagnosing TBLN at PMGH
ABSTRACT
This study evaluated occurrences of Leishmania infantum in dogs in the municipality of Palmas, Tocantins, comparing diagnostic data obtained using the polymerase chain reaction (PCR) and parasitological diagnosis. Blood samples and lymph node aspirates were collected from 63 dogs of males and females and various ages and races, with or without owners, between August 2009 and June 2010. Slides containing smears of lymph node aspirates were stained with Giemsa stained. In PCR, the 145 bp target sequence of the LT1 fragment, located in the Leishmania donovani kDNA minicircle was detected using the RV1 and RV2 oligonucleotide primers. The chi-square test revealed that there was a significant relationship between the symptoms and dogs that were positive for visceral leishmaniasis (VL). The parasitological investigation showed concordance of 66.7% with PCR on blood and 84.1% with PCR on lymph node aspirate. In addition to these tests, evaluations of the diagnoses in parallel and in series were conducted, which showed concordances with the parasitological test of 76.2% and 74.6%, respectively. The results make it possible to suggest that PCR on lymph nodes should be used in evaluating large populations (surveys) and that the parasitological test should be used for initial clinical evaluations in veterinary consultation offices.
Avaliou-se a ocorrência de Leishmania infantum em cães do município de Palmas-TO, comparando dados diagnósticos obtidos pela Reação em Cadeia da Polimerase (PCR) e pelo diagnóstico parasitológico. Foram coletadas amostras de sangue e de aspirado de linfonodo de 63 cães machos e fêmeas, várias idades e raças, domiciliares ou não de agosto de 2009 a junho de 2010. As lâminas contendo esfregaço dos aspirados de linfonodos foram coradas pelo corante Giemsa. Na PCR, a sequência alvo de 145 pb do fragmento LT1, situado no minicírculo do kDNA do grupo Leishmania donovani, foi detectada através dos oligonucleotídeos iniciadores RV1 e RV2. O teste χ² (Qui-quadrado), demonstrou haver relação significativa entre a sintomatologia e a positividade dos cães para Leishmaniose Visceral (LV). O exame parasitológico mostrou uma concordância de 66,7% com a PCR em sangue e 84,1% com a PCR de aspirado de linfonodo. Além destas análises, houve a avaliação dos diagnósticos em paralelo e em série, onde as concordâncias com o exame parasitológico foram de 76,2% e 74,6%, respectivamente. Os resultados permitem sugerir a utilização da PCR de linfonodos na avaliação de grandes populações (inquéritos), e o exame parasitológico para a avaliação clínica inicial em consultórios veterinários.