Mycobacterial Culture Results Research Articles

Diagnostic Value of Targeted Next-generation Sequencing in Pulmonary Mycobacterial Infections.

This study aimed to explore the diagnostic value of novel technique-targeted next-generation sequencing (tNGS) of bronchoalveolar lavage fluid (BALF) in pulmonary mycobacterial infections. This retrospective study was conducted on patients who underwent bronchoscopy and tNGS, smear microscopy, and mycobacterial culture of BALF. Patients with positive Mycobacterium tuberculosis (MTB) culture or GeneXpert results were classified into the tuberculosis case group. Those diagnosed with nontuberculous mycobacteria (NTM)-pulmonary disease (NTM-PD) composed the case group of NTM-PD patients. The control group comprised patients without tuberculosis or NTM-PD. Sensitivity, specificity, and receiver operating characteristic (ROC) curves were used to evaluate the diagnostic performance. For tuberculosis patients with positive mycobacterial culture results, the areas under the ROC curves (AUCs) for tNGS, GeneXpert, and smear microscopy were 0.975 (95% CI: 0.935, 1.000), 0.925 (95% CI: 0.859, 0.991), and 0.675 (95% CI: 0.563, 0.787), respectively. For tuberculosis patients with positive GeneXpert results, the AUCs of tNGS, culture, and smear microscopy were 0.970 (95% CI: 0.931, 1.000), 0.850 (95% CI: 0.770, 0.930), and 0.680 (95% CI: 0.579, 0.781), respectively. For NTM-PD, the AUCs of tNGS, culture, and smear-positive but GeneXpert-negative results were 0.987 (95% CI: 0.967, 1.000), 0.750 (95% CI: 0.622, 0.878), and 0.615 (95% CI: 0.479, 0.752), respectively. The sensitivity and specificity of tNGS in NTM-PD patients were 100% and 97.5%, respectively. tNGS demonstrated superior diagnostic efficacy in mycobacterial infection, indicating its potential for clinical application.

Evaluation of mycobacterial microscopy and culture results from clinical samples: A five-year analysis.

Ehrlich-Ziehl-Neelsen (EZN) staining and culture methods are often used to diagnose tuberculosis. This study aimed to determine the acidfast bacteria (AFS) positivity rates in various clinical samples sent to our laboratory over five years and the growth and resistance rates in two different (solid and liquid) cultures and compare them with the data from Türkiye and the world. A total of 62.456 clinic samples were accepted in the microbiology laboratory between 2019 and 2024. The mycobacterial culture was performed by searching for acid-resistant bacilli microscopically and parallel inoculation media [solid Löwenstein-Jensen (L-J) and MGIT 960 liquid]. Those growing in the MGIT 960 system were identified using BD MGIT TBC Identification test kits that detect the MPT64 antigen. AFS and MPT64 antigenpositive samples were identified as Mycobacterium tuberculosis complex (MTBC) while AFS-positive samples and MPT64 antigen-negative results were classified as non-tuberculous mycobacteria (NTM). Drug susceptibility testing was performed with the BACTEC MGIT 960 SIRE kit. Susceptibility to NTM samples was not performed. Out of a total of 120.829 samples, 95.101 were lung samples and 25.728 were extrapulmonary samples. AFS positivity was detected in 2961 (2.4%) samples. MTBC grew in 6854 (5.6%) samples, and NTM grew in 1506 (1.24%) samples. Contamination was detected in 7171 (5.9%) media. Two thousand one hundred and sixty-nine susceptibility tests were performed. Considering antibiotic resistance rates, isoniazid resistance was detected in 154 (7%), rifampicin resistance in 140 (6.4%), ethambutol resistance in 18 (0.8%), and streptomycin resistance in 120 (0.5%) samples. All four-drug resistance was observed in 91 (4.1%) samples. AFP positivity and resistance rates for rifampicin have decreased significantly, while there have been no significant changes in NTM rates over the years. When our data was determined, the sensitivity of microscopy was low. It is understood that mycobacterial culture and microscopy must be evaluated together to exclude tuberculosis infection. The high mycobacterial culture positivity rate, which is 5.6%, is due to the high number of follow-up patients and new referrals. It is seen that the change in sensitivity rates is due to the period of the COVID-19 epidemic, and it is similar to World Health Organization (WHO) data.

Insights into mycobacteriome composition in Mycobacterium bovis-infected African buffalo (Syncerus caffer) tissue samples

Animal tuberculosis significantly challenges global health, agriculture, and wildlife conservation efforts. Mycobacterial cultures are resource-intensive, time-consuming, and challenged by heterogeneous populations. In this study, we employed a culture-independent approach, using targeted long-read-based next-generation sequencing (tNGS), to investigate the mycobacterial composition in 60 DNA samples extracted from Mycobacterium bovis infected culture-confirmed African buffalo tissue. We detected mycobacterial DNA in 93.3% of the samples and the sensitivity for detecting Mycobacterium tuberculosis complex (MTBC) was 91.7%, demonstrating a high concordance of our culture-independent tNGS approach with mycobacterial culture results. In five samples, we identified heterogenous mycobacterial populations with various non-tuberculous mycobacteria, including members of the Mycobacterium avium complex (MAC), M. smegmatis, and M. komaniense. The latter Mycobacterium species was described in South Africa from bovine nasal swabs and environmental samples from the Hluhluwe-iMfolozi Park, which was the origin of the buffalo samples in the present study. This finding suggests that exposure to environmental mycobacteria may confound detection of MTBC in wildlife. In conclusion, our approach represents a promising alternative to conventional methods for detecting mycobacterial DNA. This high-throughput technique enables rapid differentiation of heterogeneous mycobacterial populations, which will contribute valuable insights into the epidemiology, pathogenesis, and microbial synergy during mycobacterial infections.

Post-treatment Radiographic Severity and Mortality in Mycobacterium avium Complex Pulmonary Disease.

Rationale: Imaging studies are widely performed when treating Mycobacterium avium complex pulmonary disease (MAC-PD); however, the clinical significance of post-treatment radiographic change is unknown. Objectives: To determine whether a deep neural network trained with pulmonary tuberculosis could adequately score the radiographic severity of MAC-PD and then to examine relationships between post-treatment radiographic severity and its change from baseline and long-term prognosis. Methods: We retrospectively collected chest radiographs of adult patients with MAC-PD treated for ⩾6 months at baseline and at 3, 6, 9, and 12 months of treatment. We correlated the radiographic severity score generated by a deep neural network with visual and clinical severity as determined by radiologists and mycobacterial culture status, respectively. The associations between the score, improvement from baseline, and mortality were analyzed using Cox proportional hazards regression. Results: In total, 342 and 120 patients were included in the derivation and validation cohorts, respectively. The network's severity score correlated with radiologists' grading (Spearman coefficient, 0.40) and mycobacterial culture results (odds ratio, 1.02; 95% confidence interval [CI], 1.0-1.05). A significant decreasing trend in the severity score was observed over time (P < 0.001). A higher score at 12 months of treatment was independently associated with higher mortality (adjusted hazard ratio, 1.07; 95% CI, 1.03-1.10). Improvements in radiographic scores from baseline were associated with reduced mortality, regardless of culture conversion (adjusted hazard ratio, 0.42; 95% CI, 0.22-0.80). These findings were replicated in the validation cohort. Conclusions: Post-treatment radiographic severity and improvement from baseline in patients with MAC-PD were associated with long-term survival.

Xpert MTB/RIF Ultra and mycobacterial culture in routine clinical care at a paediatric hospital.

BackgroundMicrobiological confirmation of pulmonary tuberculosis (PTB) in children is a well-documented challenge. This study evaluated Xpert Mycobacterium Tuberculosis (MTB)/Rifampicin (RIF) Ultra (Ultra) and mycobacterial cultures in routine clinical care at a tertiary paediatric hospital.MethodsChildren treated for PTB and who had at least one respiratory specimen investigated by Ultra and mycobacterial culture before tuberculosis (TB) treatment was commenced were included. The findings of this retrospective study were summarised using descriptive and inferential statistics.ResultsA total of 174 children were included. The median age was 2.5 years. Microcytic anaemia, airway compression, cavitary disease and miliary TB were significantly observed in children with microbiologically confirmed TB (cTB). Tuberculosis was microbiologically confirmed in 93 (53.4%) children. The positive yield from testing the first respiratory specimens was 68/174 (39.1%) on Ultra and 82/174 (47.1%) on combined Ultra and mycobacterial culture. In the subset of children (n = 70) tested with Ultra on two sequential respiratory specimens, the incremental yield from the second specimen was 30.3%. In the subset of children (n = 16) tested with Ultra on three sequential respiratory specimens, the incremental yield from the second and third specimens was 16.7% and 0.0%, respectively. When Ultra and mycobacterial culture results were combined, the incremental yield in children who had two sequential respiratory specimens tested was 24.4% and 3.1% on Ultra and mycobacterial culture, respectively.ConclusionUltra and mycobacterial culture on a single respiratory specimen resulted in a high microbiological yield. Ultra-testing on a second respiratory specimen increased the yield of microbiologically cTB. Additional diagnostic testing may require further study.

Subsequent Antituberculous Treatment May Not Be Mandatory Among Surgically Resected Culture-Negative Pulmonary Granulomas: A Retrospective Nationwide Multicenter Cohort Study.

BackgroundHistologic diagnosis of granuloma is often considered clinically equivalent to a definite diagnosis of pulmonary tuberculosis (TB) in endemic areas. Optimal management of surgically resected granulomatous inflammation in lung with negative mycobacterial culture results, however, remains unclear.MethodsFrom 7 medical institutions in northern, middle, and southern Taiwan between January 2010 and December 2018, patients whose surgically resected pulmonary nodule(s) had histological features suggestive of TB but negative microbiological study results and who received no subsequent anti-TB treatment were identified retrospectively. All patients were followed up for 2 years until death or active TB disease was diagnosed.ResultsA total of 116 patients were enrolled during the study period. Among them, 61 patients (52.6%) were clinically asymptomatic, and 36 (31.0%) patients were immunocompromised. Solitary pulmonary nodule accounted for 44 (39.6%) of all cases. The lung nodules were removed by wedge resection in 95 (81.9%), lobectomy in 17 (14.7%), and segmentectomy in 4 (3.4%) patients. The most common histological feature was granulomatous inflammation (n=116 [100%]), followed by caseous necrosis (n=39 [33.6%]). During follow-up (218.4 patient-years), none of the patients developed active TB.ConclusionsIn patients with surgically resected culture-negative pulmonary granulomas, the incidence rate of subsequent active TB is low. Watchful monitoring along with regular clinical, radiological, and microbiological follow-up, instead of routine anti-TB treatment, may also be a reasonable option.

Utility of plasma cell-free DNA detection using homobifunctional imidoesters using a microfluidic system for diagnosing active tuberculosis

Background It is difficult to diagnose tuberculosis (TB), particularly sputum-scarce pulmonary TB and extrapulmonary TB, using conventional diagnostic tests. Since these cases require additional invasive procedures to obtain appropriate specimens, new non-invasive diagnostic tests are needed. Plasma cell-free DNA (cfDNA) detection has gained interest as a novel diagnostic test for TB as it is convenient and less invasive. Therefore, we investigated the performance of enriched cfDNA for diagnosing pulmonary TB and extrapulmonary TB. Methods All patients suspected to have TB, who consented to the use of blood for detecting cfDNA, were prospectively enrolled from January 2019 to June 2020. We categorised the patients as confirmed, probable, possible TB, and not-TB. We compared the performance of cfDNA with those of conventional diagnostic tests. Results Among the 96 patients enrolled, 40 (41.7%) had TB, including 34 with confirmed TB and six probable TB, and 41 (42.7%) did not have TB. Acid-fast bacilli microscopy, Xpert MTB/RIF, and mycobacterial culture results were positive in 12 (31.6%), 22 (61.1%), and 25 (65.8%) patients, respectively. The sensitivity and specificity of cfDNA were 80.0% and 78.1%, respectively. While the sensitivity and specificity of cfDNA were similar to those of interferon-gamma releasing assay (IGRA) (sensitivity 80.6% and specificity 71.4%), the combined sensitivity and specificity of the two assays were 94.4% and 64.3%, respectively, which can be used to rule out TB. Conclusions Plasma cfDNA assay seems to be a useful adjunct to the current tests for diagnosing TB, especially when used in combination with IGRA for ruling out TB. Abbreviations TB tuberculosis cfDNA cell-free DNA PCR polymerase chain reaction AFB acid-fast bacilli IGRA interferon-gamma releasing assay CT computed tomography HIV human immunodeficiency virus

The Performance of Real-Time Polymerase Chain Reaction in Patients with Scanty Positive Acid-Fast Bacilli Sputum Smear in Diagnosis of Pulmonary Tuberculosis: 5-Year Retrospective Study

Objective: To assess the performance of real-time polymerase chain reaction (RT-PCR) to diagnosis pulmonary tuberculosis in patients with scanty positive acid-fast bacilli sputum smears, in a single hospital.Materials and Methods: All patients, who had scanty positive AFB sputum smears in Songklanagarind Hospital; between 2015 and 2019 were included. Demographic data, clinical data, radiographic findings, RT-PCR and mycobacterial culture results were reviewed. Results: From a total of 269 patients reporting scanty AFB smears, 116 patients (43.1%) had cultures confirmed as M. tuberculosis. From overall, samples from 92 patients with scanty AFB smear were processed for RT-PCR. There were 26 (28.3%) isolates having positive RT-PCR test results. Of these 26 isolates that RT-PCR positive, 25 (96.2%) were culture positive, while only 1 (3.8%) were culture negative. A remaining 66 samples that RT-PCR negative, 15 (22.7%) were culture positive for tuberculosis. Using mycobacterial cultures as the gold standard, the sensitivity, specificity, positive predictive value and negative predictive value of RT-PCR were 62.5%, 98.1%, 96.2%, and 77.3%, respectively. Pulmonary consolidation and cavity on chest radiograph were associated with the growth of M. tuberculosis, with an OR of 2.3 (95% C.I. 0.26-0.73) and 3.4 (95% C.I. 1.2-9.9), respectively.Conclusion: Less than half of the patients with scanty smears had culture-confirmed tuberculosis; RT-PCR also has low sensitivity. Consequently, a negative RT-PCR does not exclude tuberculosis; especially in cases of a high index for clinical suspicion. Radiographic findings; including pulmonary consolidation and cavities, are helpful predictors for supporting this diagnosis.

Coinfection With Multiple Nontuberculous Mycobacteria as a Possible Exacerbating Factor in Pulmonary Nontuberculous Mycobacteriosis: Clone Library Analysis Using the 16S Ribosomal RNA Gene

Mycobacterial culture is the gold standard for the diagnosis of nontuberculous Mycobacterium (NTM) infections. However, this method is not suitable for detection of coinfection with different NTMs. The goal of this study was to determine if clone library analysis of BAL fluid (BALF) was useful for detection of NTM phylotypes, including multiple NTM phylotypes, in pulmonary NTM infections. BALF samples obtained from 120 patients with suspected pulmonary NTM infections were retrospectively evaluated by using the mycobacterial culture and clone library methods between July 2010 and August2016. In total, 55 (45.8%) patients were diagnosed as NTM positive according to results of mycobacterial culture, and 52 patients were NTM positive as determined by using the clone library method. Furthermore, 45 (86.5%) and seven (13.5%) patients exhibited a single phylotype (mono-phylotype group) and multiple phylotypes of NTM (multi-phylotype group), respectively. Compared with the mono-phylotype group, the multi-phylotype group had a significantly higher incidence of adverse chest CT findings (P= .048). In addition, 11 patients who were NTM negative according to results of BALF mycobacterial culture were determined to be NTM positive according to the clone library method. Six of these 11 patients were eventually diagnosed as NTM positive by using mycobacterial culture results within 6.2 ± 2.1months following the initial sample collection. Coinfection multiple phylotypes could be associated with adverse clinical findings. In addition, patients who test positive for NTM genes but negative for mycobacterial culture may be diagnosed with NTM lung infection within 1 year of the initial sample collection. Further follow-up of these patients may facilitate early detection of NTM species.

Field performance of the Abbott RealTime MTB assay for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting

IntroductionThe sensitivities of conventional mycobacterial culture in solid or liquid media and acid-fast bacilli (AFB) smear microscopy for Mycobacterium tuberculosis complex (MTBC) detection in extrapulmonary specimens are suboptimal. We evaluated the field performance of the Abbott RealTime MTB assay for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting. MethodsThe total number of extrapulmonary specimens with mycobacterial culture and PCR results was 566: sterile fluids (n=278), non-sterile fluids (n=147), lymph node material (n=69) tissue biopsies (n=63), and abscess aspirates (n=9). A composite standard consisting of mycobacterial culture results, clinical treatment response to anti-TB drugs, when administered, and histopathology, radiological and laboratory findings were used as a reference for sensitivity and specificity calculations. ResultsMycobacterial cultures and PCR were positive in 17 and 28 specimens, respectively. The overall agreement between culture and PCR was moderate (Cohen's kappa coefficient: 0.549; P=0.0001). Taking as a reference our composite standard, the sensitivity of the Abbott PCR assay was 77.7%, the specificity 99.5%, the PPV 95.4%, and the NPV 98.8%. In turn, the sensitivity of the mycobacterial culture was 62.9%, the specificity and PPV 100%, and the NPV 97.9%. ConclusionThe good field performance of the Abbott RealTime MTB assay makes it valuable for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting. The use of molecular methods along with culture improves the diagnosis of extrapulmonary tuberculosis.

Management of Australian Adults with Bronchiectasis in Tertiary Care: Evidence-Based or Access-Driven?

Australian data regarding the management of patients with bronchiectasis is scarce. We sought to compare the management of adults with bronchiectasis attending tertiary Australian centres with recent national and international guidelines. The Australian Bronchiectasis Registry is a centralised database of patients with radiologically confirmed bronchiectasis unrelated to cystic fibrosis recruited from 14 tertiary Australian hospitals. We excluded children (<18years) and those with incomplete data, leaving 589 adults for cross-sectional analyses. We compared the proportion of patients receiving certain therapies, as compared to the proportion eligible for those treatments according to the current guidelines and baseline clinical information available from the registry. Pulmonary rehabilitation was attended by 22%, although it was indicated in 67% of the cohort. Airway clearance was undertaken in 52% of patients, although 71% reported chronic productive cough. Sputum bacterial culture results were available for 59%, and mycobacterial culture results were available for 29% of the cohort. Inhaled antibiotics were used in half of potentially eligible patients. Despite guideline recommendations against routine use, inhaled corticosteroids were used in 48% of patients. Long-term macrolides were used in 28% of participants. Discrepancies exist between guideline recommendations and real-world treatment of bronchiectasis in Australia, even in tertiary centres. These findings suggest the need for increased patient referral to pulmonary rehabilitation, increased attention to airway clearance, increased collection of sputum samples (especially for mycobacterial culture) and rationalisation of inhaled corticosteroid use. These findings encourage a review of treatment access and will inform ongoing education to promote evidence-based care for people living with bronchiectasis.

Field performance of the Abbott RealTime MTB assay for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting

IntroductionThe sensitivities of conventional mycobacterial culture in solid or liquid media and acid-fast bacilli (AFB) smear microscopy for Mycobacterium tuberculosis complex (MTBC) detection in extrapulmonary specimens are suboptimal. We evaluated the field performance of the Abbott RealTime MTB assay for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting. MethodsThe total number of extrapulmonary specimens with mycobacterial culture and PCR results was 566: sterile fluids (n=278), non-sterile fluids (n=147), lymph node material (n=69) tissue biopsies (n=63), and abscess aspirates (n=9). A composite standard consisting of mycobacterial culture results, clinical treatment response to anti-TB drugs, when administered, and histopathology, radiological and laboratory findings were used as a reference for sensitivity and specificity calculations. ResultsMycobacterial cultures and PCR were positive in 17 and 28 specimens, respectively. The overall agreement between culture and PCR was moderate (Cohen's kappa coefficient: 0.549; P=0.0001). Taking as a reference our composite standard, the sensitivity of the Abbott PCR assay was 77.7%, the specificity 99.5%, the PPV 95.4%, and the NPV 98.8%. In turn, the sensitivity of the mycobacterial culture was 62.9%, the specificity and PPV 100%, and the NPV 97.9%. ConclusionThe good field performance of the Abbott RealTime MTB assay makes it valuable for the diagnosis of extrapulmonary tuberculosis in a low-prevalence setting. The use of molecular methods along with culture improves the diagnosis of extrapulmonary tuberculosis.

Identification of Mycobacterium tuberculosis isolated from culture-negative pulmonary and extra-pulmonary samples in cases of suspected tuberculosis.

Introduction: Mycobacterium tuberculosis is the cause of pulmonary and extra-pulmonary tuberculosis. Latent tuberculosis is asymptomatic and the results of mycobacterial culture in this case are negative. The purpose of this study was to determine the prevalence of M. tuberculosis in negative cultures of pulmonary and extra-pulmonary samples from suspected tuberculosis patients in Yazd city.Methods: Specimens were collected from 44 patients with suspected pulmonary and extra-pulmonary tuberculosis. The culture result of all samples was negative and DNA was extracted from culture-negative samples. Then the IS6110 sequence of M. tuberculosis was determined by PCR, and the presence of 16S rRNA and rrnA-PCL1 was checked by real-time PCR. Data were analyzed using SPSS software.Results: Of the 44 pulmonary and extra-pulmonary samples, M. tuberculosis DNA was detected in 12 cases (27%) by PCR. Of the 12 positive cases of M. tuberculosis, 9 were detected in lung samples and 3 in extra-pulmonary samples. For rrnA-PCL1 and 16S rRNA genes, 10 samples (23%) were confirmed positive by real-time PCR. The frequency distributions of M. tuberculosis according to PCR and real-time PCR were not significantly different (p=0.403).Conclusion: Latent tuberculosis is characterized by the absence of clinical symptoms and the absence of bacilli in the culture. Regardless of the statistical analysis of results, PCR more effectively detects M. tuberculosis than does real-time PCR. According to the results, detection of M. tuberculosis in pulmonary and extra-pulmonary samples with culture-negative by PCR is reliable.

Development and validation of external quality assessment panels for mycobacterial culture testing to diagnose tuberculosis in China.

Mycobacterial culture remains the gold standard for detection of Mycobacterium tuberculosis (MTB) in clinical samples. However, no external quality assessment (EQA) tools exist to validate results obtained using this sophisticated method. Therefore, we developed EQA panels to assess the quality of mycobacterial culture results produced by designated TB hospitals in China. Artificial sputum containing methylcellulose was used to supplement quantified mycobacterial solutions to simulate culture-negative and culture-positive clinical sputum samples of low or high mycobacterial concentration, respectively. After storage of the quantified simulated EQA panels for 4weeks at 4°C, experimental bacterial quantification of the panels was again conducted, with no impact of artificial sputum on mycobacterial culture results observed. Next, 47 tuberculosis (TB) hospitals were recruited for evaluation of the EQA panels. Overall, 29 hospitals (61.7%) produced mycobacterial culture test results matching expected results for the EQA panels, while the remaining 18 (38.3%) hospitals did not. False-negative results for the low mycobacterial concentration panel sample accounted for 33 (73.3%) diagnostic errors. Compared with hospitals using solid culture methods as a control group, hospitals using the liquid culture method were less likely to produce uncertified results (aOR 0.064, 95% CI 0.005-0.770). In conclusion, we first developed then evaluated EQA panels for validation of mycobacterial culture testing in China. Our data demonstrate that approximately one-third of TB hospitals failed to produce results that met criteria for classification as certified mycobacterial culture testing providers, emphasizing the importance of quality control and quality assurance in TB diagnostics.

Nontuberculous mycobacterial and Nocardia infections mimicking pulmonary tuberculosis: a retrospective study of a general hospital patient population in China.

Purpose. In this study, we differentiated between tuberculosis (TB) and infections caused by nontuberculous mycobacteria (NTM) or Nocardia in a tertiary general hospital in China. Differences in clinical manifestations and factors between respiratory infections associated with these organisms were also investigated.Methodology. A retrospective analysis was conducted for suspected pulmonary TB patients with positive bacterial culture results under treatment at Wangjing Hospital, a tertiary general hospital, between January 2014 and June 2017. Sputum samples were submitted for liquid culture and species identification by mass spectrometry.Results. Between January 2014 and June 2017, a total of 3981 suspected TB cases were analysed, of which 151 (3.8 %) exhibited positive mycobacterial culture results. Using mass spectrometry, the 151 isolates were classified into three groups: Mycobacterium tuberculosis (MTB) (n=112; 74.2 %), NTM (n=21 13.9 %) and Nocardia (n=18; 11.9 %). The NTM and Nocardia prevalence rates were significantly higher amongst elderly patients [aged ≥65 years; odds ratio (95 % confidence interval): 3.89 (1.05-14.38) for NTM; odds ratio (95 % confidence interval): 5.10 (1.09-23.91) for Nocardia]. In addition, treatment with immunosuppressive therapy [odds ratio (95 % confidence interval): 3.92 (1.16-13.27)] was identified as a risk factor for Nocardia infection in these patients.Conclusion. Our results demonstrated that a quarter of culture-positive 'suspected TB patients' harboured NTM or Nocardia infections. Notably, nearly all patients with non-TB infections presented with clinical syndromes mimicking pulmonary TB. Individuals receiving immunosuppressive therapy were at greater risk of acquiring Nocardia infections.

Factors Associated With Sputum Culture-Negative vs Culture-Positive Diagnosis of Pulmonary Tuberculosis

Recognition of active tuberculosis (TB) in its earliest stages could reduce morbidity and prevent advancement to transmissible disease. Little is published about the occurrence and presentation of sputum culture-negative pulmonary TB (PTB), an early paucibacillary but often underrecognized disease state. To assess differences between culture-negative and culture-positive PTB regarding occurrence, clinical presentation, radiographic findings, demographics, and comorbidities. Cross-sectional study in which surveillance data of adult patients with PTB reported to the New York City Department of Health in New York, New York, from 2011 through 2013, ie, years for which demographic, clinical, and radiographic data were collected. Patients were aged 18 years or older, had signs of pulmonary disease, and had mycobacterial sputum culture results; those with HIV coinfection or a TB diagnosis within 2 years prior to presentation were excluded. Culture-negative PTB was defined as clinical and radiographic presentation consistent with TB, 3 negative results on sputum culture, and improvement with antituberculous treatment. The analyses were performed between 2015 and 2016; notably, the proportion of reported patients with culture-negative PTB has remained consistent during the past 2 decades. The occurrence of culture-negative PTB among all patients with PTB was calculated, and demographics, comorbidities, symptoms, and radiographic findings were compared between culture-negative and culture-positive PTB. Of the 796 patients with PTB (median [interquartile range] age, 41 [29-54] years; 499 [63%] men) who met criteria for analysis, 116 (15%) had negative results on sputum culture. Patients with culture-negative PTB compared with culture-positive PTB were less frequently male (53% vs 64%; P = .03) and presented with a significantly lower frequency of cough (68% vs 89%; P < .001), weight loss (39% vs 51%; P = .03), and cavitation on both chest radiograph (7% vs 28%; P < .001) and chest computed tomographic scan (26% vs 59%; P < .001). Given the lack of criterion-standard test confirmation and the relative paucity of symptoms and radiological abnormalities, culture-negative PTB is likely underdiagnosed and its occurrence underestimated globally. Awareness of these findings, enhanced diagnostic approaches, and, ideally, better biomarkers could improve detection and treatment of this early disease and reduce the development of transmissible TB.

Clinical Characteristics and Radiologic Features of Immunocompromised Patients With Pauci-Bacillary Pulmonary Tuberculosis Receiving Delayed Diagnosis and Treatment.

BackgroundPauci-bacillary pulmonary tuberculosis (TB) can be delayed to diagnose and start anti-TB therapy, especially in immunocompromised patients. We therefore evaluated the clinical and radiologic features of these delayed cases.MethodsImmunocompromised adult patients with pauci-bacillary pulmonary TB were retrospectively enrolled in a tertiary hospital in an intermediate–TB burden country over a 5-year period. We defined “missed TB” or “not-missed TB” patients as those who started anti-TB therapy after or before positive mycobacterial culture results, respectively.ResultsOf 258 patients, 134 (52%) were classified in the missed TB group, and 124 (48%) in the not-missed TB group. Positive results of molecular tests including MTB polymerase chain reaction and/or Xpert TB/RIF were only obtained in the not-missed TB group (54/106, 54%). The median diagnostic delay in the missed TB group was longer than in the other group (30 vs 6 days; P < .001). In the missed TB group, the most common working diagnoses were pneumonia (46, 34%) and lung metastasis of malignancy (40, 30%). Typical radiologic findings for TB, such as upper lobe predominance and centrilobular nodules with tree-in-bud appearance, were less common in the missed TB group than in the other group. Old age (odds ratio [OR], 1.03), solid organ transplant (OR, 3.46), solid tumor (OR, 3.83), and hematologic malignancy (OR, 4.04) were independently associated with missed TB.ConclusionsCare is needed to differentiate pauci-bacillary TB, especially in immunocompromised patients with the mentioned risk factors, even without the usual radiologic features of TB. Additional rapid diagnostic tests to rule out pauci-bacillary TB are urgently needed.

Atypical mycobacterial infection, a diagnostic and therapeutic challenge-Case report and review of literature

As atypical mycobacterial disease is very difficult to be differentiated from Mycobacterium tuberculosis, mycobacterial culture results can be the corner stone to solve the problem and avoid the un-necessary suffering of the patient and in the same time it helps in prescribing the correct drug regime for the patient. Here we present a case of a 23-year-old female who underwent LUCS one year back that was complicated with development of multiple abdominal wall abscesses. Initially she was treated with a combination of intermittent surgical drainage and prolonged antibiotic course, later antitubercular drugs were put on based on the positive AFB smear and biopsy report. This case is of interest that Mycobacterium abscessus was isolated from the patient who was improved after therapy with sensitive drugs. Our case highlights the fact that NTM disease should be put into consideration in patients with positive AFB smear and requires referral of samples to specialized microbiology laboratories.

Antibody response against Mycobacterium avium complex in cystic fibrosis patients measured by a novel IgG ELISA test

BackgroundEarly signs of Mycobacterium avium complex pulmonary disease can be missed in patients with cystic fibrosis due to subclinical infection or delays in mycobacterial culture. The aim of this study was to determine the diagnostic accuracy of a novel enzyme linked immunosorbent assay for immunoglobulin G against Mycobacterium avium complex, which could help stratify patients according to risk. MethodsA retrospective cross sectional analysis of serum samples from the Copenhagen Cystic Fibrosis Center was performed. Corresponding clinical data were reviewed and patients with cystic fibrosis were assigned to one of four groups based on their mycobacterial culture results. In addition, anti-Mycobacterium avium complex immunoglobulin G levels were measured longitudinally before and after first positive culture in the period 1984–2015. ResultsThree-hundred and five patients with cystic fibrosis were included with a median of five nontuberculous mycobacterial cultures. Four individuals had Mycobacterium avium complex pulmonary disease at the time of cross sectional testing and their median antibody level was 22-fold higher than patients with no history of infection (1820 vs. 80 IgG units; p < 0.001). Test sensitivity was 100% (95% CI 40–100) and specificity 77% (95% CI 72–81). Longitudinal kinetics showed rising antibodies prior to first positive culture suggesting diagnostic delay. ConclusionsAntibody screening for Mycobacterium avium complex may be used as a supplement to culture. Although confirmation in a larger cohort is needed, our findings suggest that stratifying a cystic fibrosis population into high- and low-risk groups based on antibody levels may help clinicians identify patients in need of more frequent culture.

Evaluation of the SD Bioline TB Ag MPT64 test for identification of Mycobacterium tuberculosis complex from liquid cultures in Southwestern Uganda.

BackgroundTo confirm presence of Mycobacterium tuberculosis complex, some tuberculosis culture laboratories still rely on para-nitrobenzoic acid (PNB), a traditional technique that requires sub-culturing of clinical isolates and two to three weeks to give results. Rapid identification tests have improved turnaround times for mycobacterial culture results. Considering the challenges of the PNB method, we assessed the performance of the SD Bioline TB Ag MPT64 assay by using PNB as gold standard to detect M. tuberculosis complex from acid-fast bacilli (AFB) positive cultures.ObjectivesThe aim of this study was to determine the sensitivity, specificity and turnaround time of the SD MPT64 assay for identification of M. tuberculosis complex, in a setting with high prevalence of tuberculosis and HIV.MethodsA convenience sample of 690 patients, with tuberculosis symptoms, was enrolled at Epicentre Mbarara Research Centre between April 2010 and June 2011. The samples were decontaminated using NALC-NaOH and re-suspended sediments inoculated in Mycobacterium Growth Indicator Tubes (MGIT) media, then incubated at 37 °C for a maximum of eight weeks. A random sample of 50 known negative cultures and 50 non-tuberculous mycobacteria isolates were tested for specificity, while sensitivity was based on AFB positivity. The time required from positive culture to reporting of results was also assessed with PNB used as the gold standard.ResultsOf the 138 cultures that were AFB-positive, the sensitivity of the SD MPT64 assay was 100.0% [95% CI: 97.3 – 100] and specificity was 100.0% (95% CI, 96.4 – 100). The median time from a specimen receipt to confirmation of strain was 10 days [IQR: 8–12] with SD MPT64 and 24 days [IQR: 22–26] with PNB.ConclusionThe SD MPT64 assay is comparable to PNB for identification of M. tuberculosis complex and reduces the time to detection.