Contribution of microbiology in the diagnosis of tuberculosis in Castile and León (Spain): Findings of the GRUMICALE 2013 study. / Contribución de la microbiología al diagnóstico de la tuberculosis en Castilla y León: conclusiones del estudio GRUMICALE 2013.

INTRODUCTION AND OBJECTIVES: A retrospective study was conducted by collecting microbiological tuberculosis (TB) data in Castile and León during the year 2013 in order to determine the incidence and distribution of TB, and resistance to the tuberculostatic drug, and compare them with the epidemiological data provided by the Department of Epidemiological Surveillance (SIVE). MATERIAL AND METHODS: Microbiologists of the 14 hospitals of the Castile and León public health network (GRUMICALE) collected epidemiological, microbiological, and management data from the Microbiology laboratories in the community during the year 2013. A single isolate of Mycobacterium tuberculosis complex (MTC) per patient was considered. RESULTS: The study included a total of 270 MTC isolates (an incidence rate of 11.63 cases/100,000 inhab./year). A total of 288 cases of TB (11.43 cases/100,000 inhab. year) were recovered using epidemiological data, which included 243 confirmed, 29 suspected, and 16 as probable cases. Pulmonary TB was predominant, followed a long way off by the pleural TB and the remaining locations. A total of 27,620 samples were processed for mycobacterial detection. Mycobacterial growth was observed in 3.46% of automated fluid cultures, and 50.37% were positive by direct staining of the smear. Resistance to one tuberculostatic drug, mostly to isoniazid, was observed in 16 (5.92%) isolates of Mycobacterium tuberculosis (MT). The province with greater incidence and number of isolates was León (24.23 cases/100,000 inhab./year), with the highest being observed in El Bierzo health area (30.46 cases/100,000 inhab./year). CONCLUSIONS: An adequate collection of microbiological information is essential to determine the epidemiology of TB in our region.

Detection of Mycobacterium tuberculosis complex by nested polymerase chain reaction in pulmonary and extrapulmonary specimens / Detecção do complexo Mycobacterium tuberculosis por nested polymerase chain reaction em espécimes pulmonares e extrapulmonares

OBJECTIVE: To compare the performance of nested polymerase chain reaction (NPCR) with that of cultures in the detection of the Mycobacterium tuberculosis complex in pulmonary and extrapulmonary specimens. METHODS: We analyzed 20 and 78 pulmonary and extrapulmonary specimens, respectively, of 67 hospitalized patients suspected of having tuberculosis. An automated microbial system was used for the identification of Mycobacterium spp. cultures, and M. tuberculosis IS6110 was used as the target sequence in the NPCR. The kappa statistic was used in order to assess the level of agreement among the results. RESULTS: Among the 67 patients, 6 and 5, respectively, were diagnosed with pulmonary and extrapulmonary tuberculosis, and the NPCR was positive in all of the cases. Among the 98 clinical specimens, smear microscopy, culture, and NPCR were positive in 6.00%, 8.16%, and 13.26%, respectively. Comparing the results of NPCR with those of cultures (the gold standard), we found that NPCR had a sensitivity and specificity of 100% and 83%, respectively, in pulmonary specimens, compared with 83% and 96%, respectively, in extrapulmonary specimens, with good concordance between the tests (kappa, 0.50 and 0.6867, respectively). CONCLUSIONS: Although NPCR proved to be a very useful tool for the detection of M. tuberculosis complex, clinical, epidemiological, and other laboratory data should also be considered in the diagnosis and treatment of pulmonary and extrapulmonary tuberculosis. .

OBJETIVO: Comparar o desempenho da técnica nested polymerase chain reaction (NPCR) com aquele de culturas na detecção do complexo Mycobacterium tuberculosis em espécimes pulmonares e extrapulmonares. MÉTODOS: Analisamos 20 e 78 espécimes pulmonares e extrapulmonares, respectivamente, de 67 pacientes hospitalizados com suspeita de tuberculose. Um sistema automatizado foi utilizado na identificação de culturas de Mycobacterium spp., e M. tuberculosis IS6110 foi utilizada como sequência alvo na NPCR. A estatística kappa foi utilizada para verificar a concordância entre os resultados. RESULTADOS: Entre os 67 pacientes, 6 e 5, respectivamente foram diagnosticados com tuberculose pulmonar e extrapulmonar, e a NPCR foi positiva em todos os casos. Entre os 98 espécimes clínicos, a baciloscopia, cultura e NPCR foram positivas em 6,00%, 8,16% e 13,26%, respectivamente. Comparando-se os resultados da NPCR com aqueles da cultura (padrão ouro) nos espécimes pulmonares, a sensibilidade e a especificidade foram 100% e 83%, respectivamente, enquanto essas nos espécimes extrapulmonares foram 83% e 96% respectivamente, com boa concordância entre os testes (kappa, 0,50 e 0,6867, respectivamente). CONCLUSÕES: Embora a NPCR tenha se mostrado uma ferramenta muito útil na detecção do complexo M. tuberculosis, No entanto, os resultados positivos da NPCR devem ser associados à clínica, dados clínicos, epidemiológicos e outros dados laboratoriais devem também ser considerados no diagnóstico e tratamento da tuberculose pulmonar e extrapulmonar. .

The role of the third acid-fast bacillus smear in tuberculosis screening for infection control purposes: A controversial topic revisited.

INTRODUCTION: Recent studies have suggested that two negative acid-fast bacillus (AFB) smears may be as effective as three when screening patients with suspected Mycobacterium tuberculosis for respiratory isolation purposes. However, current recommendations in Canada, the United States and Europe still support a three-smear approach. METHODS: The microbiology database of a tertiary care hospital was searched for sputum, tracheal aspirates and bronchoalveolar lavage samples from 2003 to 2007 that had been sent for mycobacterial testing. The first patient specimen to become AFB smear positive was noted. As well, the time required to collect the third specimen in hospitalized patients who remained smear negative was used to estimate the savings in isolation costs associated with a two-smear approach. RESULTS: There were 8347 respiratory specimens from 5168 patients in the five-year period. Of these patients, 2.2% (116 of 5168) were AFB smear positive, of whom 55.2% (64 of 116) were culture positive for Mycobacterium tuberculosis. Overall 89% (57 of 64) of patients were identified as being AFB smear positive by the first smear, 7.8% (five of 64) were identified by the second smear and 3.2% (two of 64) were identified by further smears. Smear-negative patients spent a combined 710 days in isolation awaiting collection of the third sample at a cost of approximately $142,000 over five years. CONCLUSION: A two-smear approach for discontinuation of respiratory isolation precautions is safe and has the potential to reduce hospital expenditures.