Comparação entre três métodos de coloração a frio no diagnóstico primário de tuberculose: um estudo piloto

Abstract

Objective: In developing countries, sputum smear microscopy is the main tool for pulmonary tuberculosis case finding. The objective of the present study was to evaluate the diagnostic efficacy of Gabbett's staining (GS) and modified cold staining (MCS), both of which are two-step methods, in comparison with that of fluorescent staining (FS), which is a three-step method, for the detection of AFB in sputum smears. Methods: Our sample comprised 260 sputum samples collected from individuals suspected of having pulmonary tuberculosis at Kasturba Hospital, in Manipal, India. Smears were prepared in triplicate: one each for FS, MCS, and GS. The smears were randomly numbered so that the examiner was blinded to the sample identities. Results: Of the 260 samples, 16 (6.15%), 15 (5.77%), and 13 (5.00%) showed positive AFB results with FS, MCS, and GS, respectively. The sensitivity of GS and MCS, in comparison with that of FS, was 81.25% and 93.75%, respectively. The concordance of GS and MCS with FS was good (0.988 and 0.996, respectively), and no statistically significant differences were found. Conclusions: Although MCS and GS were found to be less sensitive than was FS, which is evaluated under fluorescence microscopy, the first two are promising methods for the diagnosis of tuberculosis.Keywords: Tuberculosis, pulmonary; Diagnostic techniques and procedures; Microscopy, fluorescence; Sputum. ResumoObjetivo: Em países em desenvolvimento, a baciloscopia é a principal ferramenta para a identificação de casos de tuberculose pulmonar. O objetivo do presente estudo foi avaliar a eficácia diagnóstica do método de coloração de Gabbett (MCG) e de um método modificado de coloração a frio (MMC), ambos em duas etapas, em comparação com a do método de coloração fluorescente (MCF), em três etapas, para a detecção de BAAR em esfregaços de escarro. Métodos: Nossa amostra consistiu de 260 amostras de escarro coletadas de casos suspeitos de tuberculose pulmonar no Kasturba Hospital, em Manipal, Índia. Os esfregaços foram preparados em triplicata, para cada um dos métodos: MCF, MMC e MCG. As lâminas foram numeradas aleatoriamente a fim de que o examinador fosse cegado quanto à identidade das amostras. Resultados: Das 260 amostras, 16 (6,15%), 15 (5,77%) e 13 (5,00%) foram positivas para BAAR com MCF, MMC e MCG, respectivamente. A sensibilidade de MCG e MMC em relação à de MCF foi de 81,25% e 93,75%, respectivamente. Houve boa concordância de MCG e MMC com MCF (0,988 e 0,996, respectivamente), e não houve diferenças estatísticas significativas. Conclusões: Embora MCG e MMC apresentaram menor sensibilidade que MCF, que é avaliado por microscopia de fluorescência, consideramos que os dois primeiros métodos sejam promissores no diagnóstico de tuberculose. with freshly filtered auramine-phenol (0.3 g of auramine and 3 mL of phenol in 97 mL of distilled water) for 7-10 min without heating. The smears were washed in running water and destained with a 3% acid/alcohol solution for 3-5 min. The slides were washed in running water and coun...

A survey of recently published cardiovascular, hematological and pneumological original articles in the Brazilian scientific press

“…Goncalves et al79 described the epidemiological monitoring of exposure to tuberculosis in a hospital environment and to analyze the profile of the disease in a general teaching hospital and suggest that the proposed indicators can potentially help standardize epidemiological monitoring procedures for nosocomial tuberculosis. Gupta et al80 In developing countries, sputum smear microscopy is the main tool for pulmonary tuberculosis case finding. The objective of the present study was to evaluate the diagnostic efficacy of Gabbett's staining (GS) and modified cold staining (MCS), both of which are two-step methods, in comparison with that of fluorescent staining (FS), which is a three-step method, for the detection of AFB in sputum smears.…”

Staining techniques for detection of acid fast bacilli: what hope does fluorescein-diacetate (FDA) vitality staining technique represent for the monitoring of tuberculosis treatment in resource limited settings

“…It has been advocated as an alternative staining technique. Procedure for Gabbet's cold staining method is carried out as described in Table 1 [25]. modification, and was also widely adopted [15].…”

“…Sputum smears could be done from direct, pretreated, and concentrated specimens to increase sensitivity of the method. The stained smear should show a light brown or blue color [15,25].…”

Comparative Study on Ziehl-Neelsen Staining (Light Microscopy), Auramine O Staining (Iled- Fluorescent Microscopy) and Culture on LJ Media of Sputum Samples for the Diagnosis of Pulmonary Tuberculosis

“…The speed, feasibility and cost effectiveness of microscopy aided with high sensitivity make it valuable tool for TB diagnosis, but for this technique the yield requirement is between 5,000 to 10,000 organisms per ml sample [7][8]. The use of fluorescent microscopy enhances the visualization by providing contrast coloration to the bacilli present in the sample [9]. There are also other methods like ELISA, Mycodot, X-ray, which are not confirmatory tests, and similarly, the advanced techniques like BACTEC, gene probe, PCR, gas liquid chromatography are costly and only available in very few laboratories and lack in specificity [10][11].…”