Comparison of different diagnostic modalities for isolation of Mycobacterium Tuberculosis among suspected tuberculous lymphadenitis patients / Comparação de diferentes modalidades de diagnóstico para isolamento de Mycobacterium tuberculosis entre pacientes com suspeita de linfadenite tuberculosa

Tuberculosis is a communicable disease with high morbidity and mortality rates in developing countries. The study's primary objective is to compare conventional methods such as acid-fast bacillus (AFB) culture and microscopy with rapid diagnostic methods. The secondary objective is to compare histopathological and microbiological findings in suspected patients with tubercular lymphadenitis. A total of 111 samples (August 2018 to September 2019) of lymph nodes were processed for AFB microscopy, AFB cultures, drug-susceptibility testing (DST), histopathology, and Xpert Mycobacterium Tuberculosis (MTB)/resistance to Rifampin (RIF) assays. Out of 111 lymph node samples, 6 (5.4%) were positive for AFB smear microscopy, 84 (75.6%) were positive for AFB culture, 80 (70.7%) were positive on Gene Xpert, and 102 (91.8%) were indicative of tuberculosis for histopathology studies. Mycobacteria growth indicator tube (MGIT) culture positivity was 84 (75.6%) higher than solid Lowenstein-Jensen (LJ) culture 74 (66.6%). Positive cultures underwent phenotypic DST. Two cases were Multidrug-resistant (MDR) on DST, while three cases were Rifampicin resistant on Gene Xpert. The sensitivity of Genexpert was (62%) against the conventional AFB culture method. The poor performance of conventional lymphadenitis diagnostic methods requires early and accurate diagnostic methodology. Xpert MTB/RIF test can help in the treatment of multidrug-resistant TB cases. Nonetheless, rapid and conventional methods should be used for complete isolation of Mycobacterium tuberculosis.

A tuberculose é uma doença transmissível com altas taxas de morbimortalidade nos países em desenvolvimento. O objetivo principal do estudo é comparar métodos convencionais, como cultura de bacilo álcool-ácido resistente (BAAR) e microscopia, com métodos de diagnóstico rápido. O objetivo secundário é comparar os achados histopatológicos e microbiológicos em pacientes com suspeita de linfadenite tubercular. Um total de 111 amostras (agosto de 2018 a setembro de 2019) de gânglios linfáticos foi processado para microscopia de AFB, culturas de AFB, teste de susceptibilidade a drogas (DST), histopatologia e Xpert Mycobacterium tuberculosis (MTB)/ensaios de resistência à rifampicina (RIF). Das 111 amostras de linfonodos, 6 (5,4%) foram positivas para baciloscopia de AFB, 84 (75,6%) foram positivas para cultura de AFB, 80 (70,7%) foram positivas para o GeneXpert e 102 (91,8%) foram indicativas de tuberculose para estudos histopatológicos. A positividade da cultura do tubo indicador de crescimento de micobactérias (MGIT) foi 84 (75,6%), maior que a cultura sólida de Lowenstein-Jensen (LJ), 74 (66,6%). As culturas positivas foram submetidas a DST fenotípico. Dois casos eram multirresistentes (MDR) ao DST, enquanto três casos eram resistentes à rifampicina no GeneXpert. A sensibilidade do GeneXpert foi 62% contra o método convencional de cultura AFB. O fraco desempenho dos métodos convencionais de diagnóstico de linfadenite requer metodologia de diagnóstico precoce e precisa. O teste Xpert MTB/RIF pode ajudar no tratamento de casos de tuberculose multirresistente. No entanto, métodos rápidos e convencionais devem ser usados para o isolamento completo do Mycobacterium tuberculosis.

De la escrófula a la linfoadenitis micobacteriana / From scrophula to mycobacterial lymphadenitis

Resumen En el siglo XIX se pensaba que la tuberculosis y la tumefacción ganglionar cervical llamada escrófula afectaban a individuos predispuestos por una "constitución diatésica" heredada. En 1882 Robert Koch demostró que lesiones tuberculosas y escrofulosas humanas eran causadas por el bacilo Mycobacterium tuberculosis. A principios del siglo XX se estableció que Mycobacterium bovis, bacilo de la tuberculosis del ganado, podía también causar linfoadenitis cervical en humanos, especialmente en niños, por la ingestión de leche de vacas enfermas. La condición disminuyó después que se controló la infección en el ganado y se introdujo la pasteurización de la leche. En 1956 se describió la linfoadenitis cervicofacial granulomatosa necrosante y supurada causada por micobacterias no tuberculosas. Afecta principalmente a niños bajo los cinco años, especialmente en países sin endemia de tuberculosis. Las linfoadenitis cervicales tuberculosas predominan en adultos jóvenes en países con tuberculosis endémica y en individuos infectados por VIH.

In the 19th century it was widely believed that both tuberculosis and cervical lymph node swelling, known as scrophula, affected individuals predisposed to an inherited "diathetic constitution". In 1882 Robert Koch proved that human tuberculosis and scrophulous lesions were caused by the bacillus Mycobacterium tuberculosis. In the early twentieth century it was stated that Mycobacterium bovis, the bacillus of cattle tuberculosis, could also cause cervical lymphoadenitis in humans, especially in children, by the intake of milk from sick cows. The incidence of this condition decreased after the infection was controlled in cattle and pasteurization of the milk was introduced. A type of granulomatous necrotizing and suppurative cervico-facial lymphadenitis associated to non-tuberculous mycobacteria was described in 1956. It mainly affects children younger than 5 years old, particularly those born in countries with non-endemic tuberculosis. Tuberculous cervical lymphadenitis is prevalent in young adults from tuberculosis-endemic countries and in HIV-infected subjects. Infectious etiology displaced the importance of a personal disposition in the development of scrophula. Nevertheless, mutations that confer susceptibility to mycobacterial infection are currently investigated.

HIV-associated tuberculous lymphadenitis: the importance of polymerase chain reaction (PCR) as a complementary tool for the diagnosis of tuberculosis - a study of 104 patients / Linfadenite tuberculosa associada ao HIV: a importância da reação em cadeia de polimerase (PCR) como ferramenta complementar para o diagnóstico da tuberculose - estudo de 104 pacientes

BACKGROUND: Lymphadenitis is common in HIV-positive patients. Diagnosis of the infections associated with this condition is complex, particularly in the case of tuberculosis. Rapid and specific detection of Mycobacterium tuberculosis (M. tuberculosis) is fundamental in ensuring adequate treatment. In addition, frequent causes of lymphadenitis such as those associated with lymphoma and histoplasmosis, among others, must be eliminated as possible causes. OBJECTIVES: To evaluate the accuracy of polymerase chain reaction as a tool for the diagnosis of lymphadenitis resulting from M. tuberculosis. METHODS: In this study, a protocol was developed using the following procedures: direct microscopy using Ziehl-Neelsen staining, culture in Lowenstein-Jensen medium, histology and polymerase chain reaction. RESULTS: A total of 104 patients were included in the study. According to histopathology, 38 patients (36 percent) were found to have nonspecific chronic lymphadenitis, 27 (26 percent) had tuberculous lymphadenitis, 11 patients (10.5 percent) had lymphoma and 9 (8.7 percent) had histoplasmosis. When Lowenstein-Jensen culture was performed, positive tests for tuberculous lymphadenitis increased by 30 percent. With polymerase chain reaction, M. tuberculosis DNA was detected in 6 out of 38 samples of non-specific chronic lymphadenitis. Three of these patients were followed up, developed symptoms of tuberculosis and were cured following specific treatment. CONCLUSION: The data obtained in this study suggest that all cases of lymphadenopathies should be submitted to histopathology, Lowenstein-Jensen or Ogawa culture and polymerase chain reaction. Polymerase chain reaction may prove to be useful in providing an early and accurate detection of cases of extrapulmonary tuberculosis in HIV-positive patients with lymphadenopathies, avoiding empirical treatment and the possible development of resistant strains.

FUNDAMENTOS: A linfadenite é comum em pacientes HIV-positivos. O diagnóstico das infecções associadas a essa condição é complexo, especialmente em relação à tuberculose. A detecção rápida e específica do Mycobacterium tuberculosis (M. tuberculosis) é essencial para o tratamento adequado. Além disso, frequentes causas de linfadenites tais como as relacionadas a linfoma, histoplasmose, e outras, devem ser afastadas. OBJETIVOS: Avaliar a importância da biópsia cirúrgica excisional das linfadenites e realização dos exames histopatológicos, exames baciloscópicos (Ziehl-Neelsen), cultura (Lowenstein-Jensen) e reação em cadeia da polimerase (PCR) com finalidade diagnostica MÉTODOS: Desenvolveu-se um protocolo para biópsias excisionais de linfonodos, adotando-se os seguintes procedimentos: exame direto de esfregaços corados pelo método de Ziehl-Neelsen, cultura em meio de Lowenstein-Jensen, exame anátomo-patológico e PCR. RESULTADOS: Ao todo foram incluídos 104 pacientes, e o exame histopatológico evidenciou 36 por cento (n = 38 pacientes) de casos de linfadenite crônica inespecífica, 26 por cento (n = 27) de linfadenite tuberculosa, 10,5 por cento (n =11) de linfoma e 8,7 por cento (n = 9) de histoplasmose. Através da cultura no meio de Lowenstein-Jensen, os casos positivos para linfadenite tuberculosa aumentaram para 30 por cento. A PCR detectou M. tuberculosis em 6 das 38 amostras de linfadenite crônica inespecífica. Três desses pacientes foram acompanhados, exibiram sintomas de tuberculose e foram curados após tratamento específico. CONCLUSÃO: Os dados obtidos neste trabalho sugerem que em todos os casos de linfadenopatia deve-se realizar exame histopatológico, cultura em Lowenstein-Jensen ou Ogawa e reação em cadeia da polimerase. A reação em cadeia da polimerase pode ser útil na detecção precoce e acurada de casos de TB extrapulmonar nos pacientes HIV-positivos com linfadenopatias, evitando-se o uso de tratamentos empíricos e o eventual desenvolvimento de cepas resistentes.

High mast cell density associated with granulomatous formation in tuberculous lymphadenitis.

Mast cells are one of the main inflammatory cells involved in the pathogenesis of tuberculosis. Previous reports revealed that mast cells participated in both acute and chronic states of infection with Mycobacterium tuberculosis through direct contact or indirect enhancement by releasing mediators. The authors evaluated mast cell density on tissue sections of tuberculous lymphadenitis stained with 0.1% toluidine blue from 45 cases, all of which were retrieved from the surgical pathology files of King Chulalongkorn Memorial Hospital from 1999 to 2006. A number of mast cells were correlated semiquantitatively with granulomas which were formed by aggregation of epithelioid histiocytes, multinucleated giant cells, and caseous necrosis. We found that mast cell density was significantly increased in lymph nodes with greater granuloma involvement (p = 0.030) and multinucleated giant cell formation (p = 0.010). These findings indicate a significant correlation between mast cell density and the granulomatous formation responsible for M. tuberculosis.

Polymerase chain reaction to identify mycobacterium tuberculosis in patients with tuberculous lymphadenopathy.

Tuberculous lymphadenopathy is often diagnosed and treated on clinical and cytopathological grounds as Mycobacterium tuberculosis remains undetected in tissue specimens from such patients. At times, lymph nodes are known to respond sluggishly to and reappear during antitubercular therapy. We report a polymerase chain reaction-based approach to confirm the presence of M. tuberculosis in 4 such patients.

A histological spectrum of host responses in tuberculous lymphadenitis.

A total of 446 lymph node biopsy specimens showing histological evidence of tuberculosis were classified into four groups based on the organization of the granuloma, the type and numbers of participating cells and the nature of necrosis. These were, hyperplastic (22.4%)--a well-formed epithelioid cell granuloma with very little necrosis, reactive (54.3%)--a well-formed granuloma consisting of epithelioid cells, macrophages, lymphocytes and plasma cells with fine, eosinophilic caseation necrosis, hyporeactive (17.7%)--a poorly organized granuloma with macrophages, immature epithelioid cells, lymphocytes and plasma cells and coarse, predominantly basophilic caseation necrosis and nonreactive (3.6%)--unorganized granuloma with macrophages, lymphocytes, plasma cells and polymorphs with non caseating necrosis. Though the number of bacilli in the sections differed in each group, there were no differences in culture positivity, Mantoux reaction or the clinical features. It is likely that the spectrum of histological responses seen in tuberculous lymphadenitis is the end result of different pathogenic mechanisms underlying the disease.

Application of PCR from the fine needle aspirates for the diagnosis of cervical tuberculous lymphadenitis

Tuberculosis remains a major public health problem worldwide. A definitive and accurate diagnosis of tuberculosis in cervical lymphadenopathy is important because satisfactory results can be achieved with chemotherapy alone, obviating surgery. Recently, fine needle aspiration cytology (FNAC) has provided an alternative and easy procedure for collection of material for cytomorphologic and bacteriologic examination. But the detection rate for M. tuberculosis from the aspirate material is still low with Ziehl-Neelson stain and even with culture. The authors therefore performed polymerase chain reaction (PCR) for mycobacterial DNA sequences in 31 cases of cytodiagnosis of tuberculous lymphadenitis and compared conventional bacteriologic methods. Ziehl-Neelson staining for acid-fast bacilli (AFB) was positive in 3 cases (10%) in direct smears, and the cultures for M. tuberculosis were positive in 6 cases (19%). In 19 (61%) among 31 samples, mycobacterial DNA fragments were detected, using the PCR method. With combined conventional and PCR method, the rate of detection was increased to 68 percent high. In conclusion, PCR is the most sensitive technique in the demonstration of M. tuberculosis in patient with clinically suspected as tuberculosis, who have AFB stain or culture negative cytology. Combined conventional and PCR methods as well as cytologic findings are of further help in the detection and characterization of M. tuberculosis.

Correlative study of histopathology and bacteriology in patients of tubercular lymphadenitis.

Histopathology as well as bacteriology of lymph node specimen are useful diagnostic tools for tuberculous lymphadenitis. In the present study, a total of 71 cases of lymphadenitis were selected for histopathological and bacteriological studies. Only 46 patients had caseating type and 4 had non-caseating type of tuberculous lymphadenitis while 21 patients revealed non-specific chronic lymphadenitis on histopathological examination. Only 6 lymph node smears were positive for acid fast bacilli (AFB), 19 cases were positive for mycobacterial culture growth. Thus, it is not necessary that the cases which are histopathologically positive will be positive for culture as well. Therefore, both bacteriology and histopathology are complimentary diagnostic tools for tuberculous lymphadenitis.

Cytologic diagnosis of tuberculous lymphadenitis in children by fine needle aspiration.

One hundred consecutively diagnosed cases of tuberculous lymphadenitis in children have been analysed retrospectively. All cases were stained by May Grunwald Giemsa for cytomorphology and Ziehl Neelsen stain for acidfast bacilli (AFB). In 52 cases the material was sufficient and AFB cultures were possible. A diagnosis of tuberculosis was made when smears showed epithelioid cell granulomas or AFB on either smears or culture. M. tuberculosis and atypical mucobacteria were cultured in 26 and 3 cases respectively. In 6 cases the diagnosis of tuberculosis would have been missed but for culture studies, the cytologic smears were necrotic and stains for AFB negative.