Project description:BackgroundThere is a paucity of data on the role of molecular methods in the diagnosis of osteoarticular tuberculosis. The present study was conducted to define the role of molecular (CBNAAT, LPA), phenotypic (AFB smear and culture) and histopathological evaluation in the diagnosis of osteoarticular TB.MethodsSeventy-seven consecutive cases of osteoarticular tuberculosis were grouped into presumptive TB cases (group A) and presumptive drug-resistant cases (group B). Tissue samples obtained were submitted for CBNAAT, LPA, AFB smear, liquid culture and histological examinations. The diagnostic accuracy of each test was reported against histologically diagnosed cases and in all tests in tandem.ResultsGroup A and group B had 65 and 12 cases, respectively. The diagnostic accuracy for tuberculosis was 84.62% by CBNAAT, 70.77% by LPA, 86.15% by molecular tests (combined), 47.69% by AFB smear, 50.77% by liquid culture and 87.69% by histology in group A, and 91.67% for CBNAAT, 83.33% for LPA, 91.67% for molecular tests (combined), 25% for AFB smear, 16.67% for liquid culture and 83.33% for histology in group B. The drug resistance detection rate was 4.62% on CBNAAT, 3.08% on LPA, 6.15% on molecular tests (combined) and 1.54% on DST in group A, while it was 33.33% on CBNAAT, 58.33% on LPA, 58.33% on molecular tests (combined) and 16.67% on DST among group B cases. Similar sensitivity rates for the various tests were obtained among both the groups on comparison with histology (taken as denominator). The addition of molecular methods increased the overall diagnostic accuracy (all tests in tandem) from 93.8 to 100% in group A and from 83.3 to 100% in group B cases.ConclusionNo single tests could diagnose tuberculosis in all cases; hence, samples should be evaluated by molecular tests (CBNAAT and LPA), AFB smear, culture and histological examinations simultaneously. The molecular tests have better demonstration of drug resistance from mycobacterial culture.Supplementary informationThe online version contains supplementary material available at 10.1007/s43465-020-00326-w.

Project description:Tsukamurella species are obligate aerobic, gram-positive, weak acid-fast, nonmotile bacilli. They are found in various environments, such as soil, water, sludge, and petroleum reservoir wastewater, and belong to the order Actinomycetales. In 2016, there was a reclassification of species within the genus Tsukamurella, merging the species Tsukamurella tyrosinosolvens (T. tyrosinosolvens) and Tsukamurella carboxydivorans. Tsukamurella species are clinically considered to be a rare opportunistic pathogen, because most reported cases have been related to bacteremia and intravascular prosthetic devices and immunosuppression. To date, it has been isolated only from human specimens, and has always been associated with clinical disease; human infections are very rare. Reported infections have included pneumonia, brain abscesses, catheter-related bloodstream infections, ocular infections, bacteremia, and sepsis presenting with septic pulmonary emboli in patients who are immunocompromised. To date, there is no commercially available test for identification. On the other hand, sequence-based identification, including matrix-assisted laser desorption ionization time-of-flight mass spectrometry, is an alternative method for identifying clinical isolates that are either slow growers or difficult to identify through biochemical profiling. The golden standards for diagnosis and optimal management still remain to be determined. However, newer molecular biological techniques can provide accurate identification, and contribute to the appropriate selection of definitive therapy for infections caused by this organism. Combinations of several antimicrobial agents have been proposed for treatment, though the length of treatment for infections has yet to be determined, and should be individualized according to clinical response. Immunocompromised patients often experience severe cases due to infection, and life-threatening T. tyrosinosolvens events associated with dissemination and/or failure of source control have occurred. Favorable prognoses can be achieved through earlier identification of the cause of infection, as well as successful management, including appropriate antibiotic therapy together with source control. Further analyses of similar cases are required to establish the most adequate diagnostic methods and treatment regimens for infections.

Project description:BackgroundSmear-negative pulmonary tuberculosis (PTB) is common and difficult to diagnose. In this study, we investigated the diagnostic value of nucleic acid amplification testing and sequencing combined with acid-fast bacteria (AFB) staining of needle biopsy lung tissues for patients with suspected smear-negative PTB.MethodsPatients with suspected smear-negative PTB who underwent percutaneous transthoracic needle biopsy between May 1, 2012, and June 30, 2015, were enrolled in this retrospective study. Patients with AFB in sputum smears were excluded. All lung biopsy specimens were fixed in formalin, embedded in paraffin, and subjected to acid-fast staining and tuberculous polymerase chain reaction (TB-PCR). For patients with positive AFB and negative TB-PCR results in lung tissues, probe assays and 16S rRNA sequencing were used for identification of nontuberculous mycobacteria (NTM). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of PCR and AFB staining were calculated separately and in combination.ResultsAmong the 220 eligible patients, 133 were diagnosed with TB (men/women: 76/57; age range: 17-80 years, confirmed TB: 9, probable TB: 124). Forty-eight patients who were diagnosed with other specific diseases were assigned as negative controls, and 39 patients with indeterminate final diagnosis were excluded from statistical analysis. The sensitivity, specificity, PPV, NPV, and accuracy of histological AFB (HAFB) for the diagnosis of smear-negative were 61.7% (82/133), 100% (48/48), 100% (82/82), 48.5% (48/181), and 71.8% (130/181), respectively. The sensitivity, specificity, PPV, and NPV of histological PCR were 89.5% (119/133), 95.8% (46/48), 98.3% (119/121), and 76.7% (46/60), respectively, demonstrating that histological PCR had significantly higher accuracy (91.2% [165/181]) than histological acid-fast staining (71.8% [130/181]), P < 0.001. Parallel testing of histological AFB staining and PCR showed the sensitivity, specificity, PPV, NPV, and accuracy to be 94.0% (125/133), 95.8% (46/48), 98.4% (125/127), 85.2% (46/54), and 94.5% (171/181), respectively. Among patients with positive AFB and negative PCR results in lung tissue specimens, two were diagnosed with NTM infections (Mycobacterium avium-intracellulare complex and Mycobacterium kansasii).ConclusionNucleic acid amplification testing combined with acid-fast staining in lung biopsy tissues can lead to early and accurate diagnosis in patients with smear-negative pulmonary tuberculosis. For patients with positive histological AFB and negative tuberculous PCR results in lung tissue, NTM infection should be suspected and could be identified by specific probe assays or 16S rRNA sequencing.

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The Acid-Fast Bacilli Smear: Hail and Farewell.

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