Recurrent tuberculosis (TB) continues to be a significant problem and is an important indicator of the effectiveness of TB control. Recurrence can occur by relapse or exogenous reinfection. Recurrence of TB is still a major problem in high-burden countries, where there is lack of resources and no special attention is being given to this issue. The rate of recurrence is highly variable and has been estimated to range from 4.9% to 47%. This variability is related to differences in regional epidemiology of recurrence and differences in the definitions used by the TB control programs. In addition to treatment failure from noncompliance, there are several key host factors that are associated with high rates of recurrence. The widely recognized host factors independent of treatment program that predispose to TB recurrence include gender differences, malnutrition; comorbidities such as diabetes, renal failure, and systemic diseases, especially immunosuppressive states such as human immunodeficiency virus; substance abuse; and environmental exposures such as silicosis. With improved understanding of the human genome, proteome, and metabolome, additional host-specific factors that predispose to recurrence are being identified. Information on temporal and geographical trends of TB cases as well as studies with whole-genome sequencing might provide further information to enable us to fully understand TB recurrence and discriminate between reactivation and new infection. The recently launched World Health Organization End TB Strategy emphasizes the importance of integrated, patient-centered TB care. Continued improvement in diagnosis, treatment approaches, and an understanding of host-specific factors are needed to fully understand the clinical epidemiological and social determinants of TB recurrence.

Background: The genus Mycobacterium has an ability to persist in hostile environments for years before its reactivation in favorable conditions. The major bottleneck in decades of mycobacterial research is a poor understanding of molecular mechanism which assists bacteria to attain dormancy and reactivation later. Methods: In this study, hydroxyl radical was quantified in aerobically growing mycobacterial cells using 2-deoxy-D-ribose assay. Furthermore, extraneous addition of hydroxyl radical in Wayne's dormancy model induced reactivation of dormant cells. The whole proteome of all three samples, namely, aerobic, Wayne dormancy, and hydroxyl radical reactivated cells was isolated, trypsin digested, and peptides are quantitatively characterized by liquid chromatography-elevated energy mass spectrometry. Results: This study reports the generation of highly reactive hydroxyl radical by Mycobacterium smegmatis during aerobic respiration. The hydroxyl radical levels can be managed by modulation of iron ions in the cellular pool. Proteomic characterization of resuscitation process highlights the increase in the level of ATPases, iron acquisition, redox response, changes in cell membrane dynamics, and cell wall hydrophobicity which is coupled with restoration of protein synthesis, carbohydrate, and lipid metabolism. In addition, two uncharacterized universal stress proteins MSMEG5245 and MSMEG3950 were uniquely identified in reactivated cells. Conclusion: Overall, the 1-hydroxypyridine-2-thione-induced reactivation process is a controlled and stepwise exit from dormancy.

Background: The main mechanism of resistance to PZA in Mycobacterium tuberculosis relies on mutations on its pyrazinamidase/nicotinamidase. Recently, a rapid colorimetric test relying on the PCR-based in vitro-synthesized-PZase assay has been reported for PZase activity determination from clinical M. tuberculosis isolates but the assay has not been compared with other tests to evaluate PZA susceptibility in M. tuberculosis isolates. Methods: In this study, we have used the PCR-based in vitro-synthesized-PZase assay to analyze the specific pyrazinamidase (PZase) activity of PncA mutants and have correlated the results to the PZA susceptibility phenotype determined by culture in acidic agar medium at pH 6.0. A set of 23 clinical isolates displaying mutated pncA genes (11 PZA-resistant and 12 PZA-susceptible) and 55 PZA-susceptible clinical strains displaying a wild-type pncA gene were tested. Results: Among the 23 mutants tested, 4 corresponded to mutations not reported before (I5T, Y99S, T142R and P77L+V131G). Of the 11 PncA mutants expressed from PZA-resistant clinical isolates, 9 were expressed in vitro at yields > 50% relative to the wild type enzyme. Among them, 6 enzymes (T47P, H51P, H51R, H57D, L85R and T142R) showed no detectable activity, while the relative activities for the 3 others, V9A (27%), G97D (10%) and A146V (28%) were low compared to the wild-type PZase. The remaining two mutants, I5T and V9G, presented very low relative expression (5%) and relative activities values of 12 and 1%, respectively. Twelve mutants were expressed from PZA-susceptible isolates. Their expression was similar to the wild type enzyme and behaved as active pyrazinamidase with specific relative activities ranging from 34 to 314%. Finally, discrepant results were observed for two mutants, V7A and P62T. Conclusion: Thus, this study provides the proof of concept that the PCR-based in vitro-synthesized-PZase assay represents a promising rapid approach for the evaluation of PZA susceptibility based on the estimation of the relative PZase activity from clinical isolates.

Background: A variety of genetic mutations are thought to be responsible for acquisition of different infections such as tuberculosis (TB). An obvious example for these variations is the link between pulmonary TB and polymorphisms within interferon-gamma receptor 1 (IFN-γ R1) gene. This project is designed to identify the role of IFN-γR1 gene polymorphism in the development of pulmonary TB among Sudanese patients attending several hospitals in Khartoum State. Methods: One hundred (n = 100) patients with active TB and fifty (n = 50) matched healthy controls were investigated for the association of two genetic polymorphisms within IFN-γR1 gene and their risk of developing pulmonary tuberculosis. Polymerase chain reaction (PCR) assay and PCR-restriction fragment length polymorphism were performed. Results: Migrated IFN-γR1 DNA bands representing genotypes and polymorphic alleles were identified. Molecular findings revealed that two genetic variants, namely, −56C and +295C deletion 12 within IFN-γR1 gene, were nonsignificantly linked with increased risk of development of pulmonary TB, P = 0.771 and 0.343, respectively. Two genetic variants within IFN-γR1 gene were examined for suggested role in inducing development of TB. Conclusion: The two genetic variants were found to have potential risk in association with active disease development among Sudanese patients. Further intensive research work involving use of large collection of samples should be conducted to verify these findings.

Background: The WHO strategy for eradication of tuberculosis (TB) by 2035 (The End TB Strategy) is aimed at an early and precise diagnosis and subsequent effective treatment of TB patients. Currently, there is no gold standard for the diagnosis of latent TB infection. This study evaluated the diagnostic capabilities of a new intradermal test using recombinant TB allergen (Diaskintest) compared with tuberculin skin test (TST) and commercial TB interferon-gamma release assays (IGRAs). Methods: A post-hoc data analysis that involved examining 860 HIV-negative, bacillus Calmette–Guérin (BCG)-vaccinated persons aged 1–65 years who visited the TB health-care institutions of Saint Petersburg to rule out or confirm an active TB was conducted from 2011 to 2016. Results: A high degree of consistency of the Diaskintest results with the enzyme-linked immunospot and QuantiFERON-TB Gold In-Tube test (ELISPOT and QFT) results was observed in the examined pediatric population (n = 696), with a Diaskintest cutoff ≥5 mm: the kappa consistency indices were 1.000 and 0.937, for ELISPOT and QFT, respectively. A high sensitivity of Diaskintest, comparable with the IGRA tests, was observed in patients with a confirmed TB diagnosis in all age groups. The sensitivity of Diaskintest in patients of the TB/MTB + group aged 18 years and older was 88.7%; of ELISPOT, 90.6%; of QFT, 87.0%. The conducted analysis has shown a high concordance of results of the commercial TB tests in adult HIV-negative patients (n = 164) with a Diaskintest cutoff ≥5 mm: the kappa indices were 0.805 and 0.636 (Diaskintest vs. ELISPOT and QFT, respectively) among BCG-vaccinated people. Conclusion: According to the WHO recommendations, replacing the TST by IGRAs is not recommended as a public health intervention in resource-constrained settings because the IGRA tests are more costly and technically complex to conduct than the TST. Diaskintest has comparable complexity to the TST and its performance is close to that of IGRA in a BCG-vaccinated population. Thus, our study demonstrates that replacing the TST by Diaskintest can be recommended as a public health intervention in resource-constrained and universal BCG vaccination settings.

Background: In low-income countries, rapid detection of tuberculosis (TB) drug resistance is often restricted by the difficulties of transporting and storing sputum samples from remote health centers to the reference laboratories where molecular tests are available. The aim of this study was to evaluate the performance of four transport and storage systems for molecular detection of rifampicin (RIF) and isoniazid (INH) resistance. Methods: This was a multicenter study. Molecular detection of RIF and INH resistance was performed directly from smear-positive TB sputa spotted on a slide, FTA card, GenoCard, and ethanol using the Genotype MTBDRplus assay. The performance of the DNA extraction method from each storage support to detect drug resistance was assessed by calculating their sensitivity and specificity compared to the phenotypic method. Results: From all sites, the overall sensitivity and specificity for RIF-resistance detection was 88% and 85%, respectively, for slides, 86% and 92%, respectively, for GenoCard, 87% and 89%, respectively, for FTA card, and 88% and 92%, respectively, for ethanol. For INH-resistance detection, the overall sensitivity and specificity was 82% and 90%, respectively, for slides, 85% and 96%, respectively, for GenoCard, 86% and 92%, respectively, for FTA card, and 86% and 94%, respectively, for ethanol. Conclusion: Smear slides and filter cards showed to be very useful tools to facilitate DNA extraction from sputum samples with the potential to accelerate the detection of drug resistance in remote areas.

Background: Mycobacterium abscessus pulmonary infection has recently emerged as a significant pathogen in patients with cystic fibrosis (CF) and is associated with significant morbidity and accelerated pulmonary decline. There is a paucity of data describing the activity of hospital biocides against this organism. Methods: M. abscessus isolates (n = 13) were recovered from CF and non-CF respiratory specimens. Seven commonly employed hospital biocides with generic ingredients as follows: acetone, propan-2-ol, diethylene glycol, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one, chlorine dioxide, 4% chlorhexidine, alcohol, and disodium carbonate, compound with hydrogen peroxide, 10% sodium hypochlorite were assayed for their biocidal activity against M. abscessus. Fresh cultures of M. abscessus were exposed to biocide in liquid medium as per manufacturers' instruction and were immediately plated following the completion of the contact period. The mean concentration of M. abscessus plated was 9.82 × 10⁶ colony-forming units (range: 1.63 × 10⁵–1.12 × 10⁸). In addition, the remaining bacteria/biocide solution was enriched nonselectively in Mueller Hinton broth (37°C/1 week) and then plated. Results: All M. abscessus isolates survived in alkyl dimethyl benzyl ammonium chloride, 5-chloro-2-methyl-2H-isothiazol-3-one (EC No. 247-500-7) and 2-methyl-2H-isothiazol-3-one, 4% Chlorhexidine™, O-phenylphenol and Sodium Lauryl Sulfate™ and disodium carbonate, compound with hydrogen peroxide. One out of 13 M. abscessus cultures was killed by Chlorine Dioxide™ and one by Sodium Dichloroisocyanurate™, representing a 5-log kill. Two isolates were killed by Alcohol™ again representing a 5 log kill. Following enrichment, O-phenylphenol and Sodium Lauryl Sulfate™ showed the greatest biocidal activity with 11/13 isolates, whereas 2/13 cultures were killed by sodium dichloroisocyanurate™. All other biocide/culture combinations yielded growth. Conclusion: These data indicate that M. abscessus may persist after exposure to several common hospital biocides. Further work is urgently needed to define unequivocal biocide contact treatments to prevent cross-infection with this mycobacterial species in this patient population and thus ensure effective infection control and prevention.

Background: Mycobacterium avium subsp. hominissuis (MAH) is an environmental opportunistic pathogen for humans and swine worldwide; in humans, the vast majority of MAH infections is due to strains belonging to specific genotypes, such as the internal transcribed spacer (ITS)-sequevars Mav-A and Mav-B that mostly cause pulmonary infections in elderly patients and severe disseminated infections in acquired immunodeficiency syndrome patients, respectively. To test whether the different types of infections in distinct patients' populations might reflect a different virulence of the infecting genotypes, MAH human isolates, genotyped by ITS sequencing and MIRU-VNTR minisatellite analysis, were studied for the capacity to infect and replicate in human macrophages in vitro. Methods: Cultures of human peripheral blood mononuclear cells and phagocytic human leukemic cell line THP-1 cells were infected with each MAH isolate and intracellular colony-forming units (CFU) were determined. Results: At 2 h after infection, i.e., immediately after cell entry, the numbers of intracellular bacteria did not differ between Mav-A and Mav-B organisms in both phagocytic cell types. At 5 days, Mav-A organisms, sharing highly related VNTR-MIRU genotypes, yielded numbers of intracellular CFUs significantly higher than Mav-B organisms in both phagocytic cell types. MIRU-VNTR-based minimum spanning tree analysis of the MAH isolates showed a divergent phylogenetic pathway of Mav-A and Mav-B organisms. Conclusion: Mav-A and Mav-B sequevars might have evolved different pathogenetic properties that might account for their association with different human infections.

Background: The environment is the nontuberculous mycobacteria (NTM) reservoir, opportunistic pathogens of great diversity and ubiquity, which is observed in the constant description of new species capable of causing infection. Since its introduction, molecular methods are essential for species identification. Most comparative studies between molecular and conventional methods, have used isolated strains from clinical samples. Methods: The aim of this study was to evaluate the usefulness of molecular methods, especially the hsp65-PRA (PCR-Restriction Enzyme Analysis), and biochemical tests in the identification of NTM recovered from water of different origins, using the sequencing of 16S rRNA and hsp 65 genes as assessment methods of the previous ones. Species identification was performed for all 56 NTM isolates what were recovered from 32 (42.1%) positive water samples, using conventional phenotypic methods, hsp65-PRA, partial sequencing of 16S rRNA and sequencing of hsp 65 genes. Results: Phenotypic evaluation and hsp65-PRA were concordant with 23 (41.1%) isolates. Also, the PRA was concordant with 16 (28.6%) and 27 (48.2%) isolates, with the partial sequencing of 16S rRNA and sequencing of hsp 65 genes, respectively. It is considered that the 19.6% (n = 11) could not be identified. Conclusion: Identification of NTM environmental isolates to the species level, especially when they are pigmented and fast-growing, both the analysis of the restriction patterns obtained by PRA and the sequencing of the 16S rRNA and hsp 65 genes are insufficient by themselves. Although they are demanding and time-consuming, biochemical tests are very useful to support data obtained by molecular methods.

Background: The Mycobacterium tuberculosis (MTB) uridine diphosphogalactofuranose (UDP)-galactopyranose mutase (UGM) is an essential flavoenzyme for mycobacterial viability and an important component of cell wall. It catalyzes the interconversion of UDP-galactopyranose into UDP-galactofuranose, a key building block for cell wall construction, essential for linking the peptidoglycan and mycolic acid cell wall layers in MTB through a 2-keto intermediate. Further, as this enzyme is not present in humans, it is an excellent therapeutic target for MTB. Thus, inhibition of this UGM enzyme is a good approach to explore new anti-TB drug. This study aims to find novel and effective inhibitors against UGM from reported natural phytochemicals and ZINC database using virtual screening approach. Methods: In this study, 148 phytochemicals with reported antitubercular activity and 5280 ZINC compounds with 70% structural similarity with the natural substrate of UGM (UDP-galactopyranose and UDP-galactofuranose) were screened against UGM. Results: In virtual screening, 19 phytochemicals and 477 ZINC compounds showed comparatively better binding affinity than natural substrates. Among them, best 10 compounds from each group were proposed as potential inhibitors for UGM based on the binding energy and protein-ligand interaction analysis. Among phytochemicals, three compounds, namely, tiliacorine, amentoflavone, and 2'-nortiliacorinine showed highest binding affinity (binding energy of −10.5, −10.4, and −10.3 Kcal/mol, respectively), while among ZINC compounds, ZINC08219848 and ZINC08217649, showing highest binding affinity (binding energy of −10.0 and −9.7 Kcal/mol, respectively) toward UGM as compared to its substrates. Conclusion: These selected compounds may be proposed as potential inhibitors of UGM and need to be tested in TB culture studies in vitro to assess their anti-TB activity.

Background: Among Mycobacterium abscessus complex infections, patients with M. abscessus subsp. abscessus (MAA) lung disease are difficult to treat and no standard therapy has been established. Few reports have investigated the drug susceptibility of these strains. We retrospectively investigated how in vitro drug susceptibility testing (DST) of MAA affects the induction of sputum conversion using pharmacotherapy. Methods: Patients with MAA lung disease diagnosed and treated between 2010 and 2014 at our hospital were enrolled and divided into Group A (sputum conversion without relapse within 1 year) and Group B (persistent positive cultured or negative conversion with relapse). MAA was identified in M. abscessus using sequence with genotyping, and DST of MAA was performed. Results: We assessed 23 patients (9 males and 14 females). There were 8 patients in Group A and 15 in Group B. Higher prevalence of susceptible isolates for clarithromycin (CAM) susceptibility on day 14 was noted in Group A than in Group B (P = 0.03) and no significant difference observed in the two groups for other drugs. Conclusions: In vitro DST of MAA, especially CAM susceptibility on day 14, affected the results of negative conversion. No other drugs were found to affect sputum culture negative conversion.

Background: Tuberculosis is well-known airborne disease caused by Mycobacterium tuberculosis. Available treatment regimen was unsuccessful in eradicating the deaths caused by the disease worldwide. Owing to the drawbacks such as prolonged treatment period, side effects, and drug tolerance, there resulted in patient noncompliance. In the current study, we attempted to develop inhibitors against unexplored key target glutamate racemase. Methods: Lead identification was done using thermal shift assay from in-house library; inhibitors were developed by lead derivatization technique and evaluated using various biological assays. Results: In indazole series, compounds 11 (6.32 ± 0.35 μM) and 22 (6.11 ± 0.51 μM) were found to be most promising potent inhibitors among all. These compounds also showed their inhibition on replicating and nonreplicating bacteria. Conclusion: We have developed the novel inhibitors against M. tuberculosis capable of inhibiting active and dormant bacteria, further optimization of inhibitor derivatives can results in better compounds for eradicating tuberculosis.

Background: Tuberculosis (TB) has been identified in skeletons over 6000 years old and still remains as the most prevalent infectious disease in the world; thus, there is a need for development of new drugs or tuning of old drugs. Nanotechnology, an advanced technology, plays a vital role in research for the diagnosis and treatment of TB, thus preventing adverse effects and drug resistance. The objective of this study was to enhance the antimycobacterial activity of isoniazid- (INH) and rifampicin (RIF)-incorporated norbornene (NOR) nanoparticles in comparison with plain INH and RIF without nanoparticles. Methods: Norbornene-polyethylene glycol – Isoniazid copolymer (NOR-PEG-INH) and norbornene polyethylene rifampicin Co polymer (NOR-PEG-RIF) were used for this study. The percentage of INH and RIF in NOR nanoparticles was 35% and 74%, respectively. Mycobacterium growth indicator tube containing Middlebrook 7H9 broth, the liquid medium, was used to analyze in vitro activity of the NOR-based drug and the plain drug. Minimum inhibitory concentration (MIC) of the drugs was determined from H37Rv control strain of mycobacterium TB (MTB). Results: The dosage of INH and RIF is minimal in the combination form with the NOR nanoparticles compared to the plain INH and RIF. The results indicate that the minimum concentration of NOR-PEG-INH and NOR-PEG-RIF required inhibiting H37Rv strain of MTB was 0.05 μg/ml and 0.5 μg/ml, respectively. The results were similar to plain INH and RIF MIC. Conclusion: Low dosage of INH and RIF along with NOR nanocarrier has similar activity to that of INH and RIF; thus this is expected to reduce adverse effects and NOR did not alter the functional activity of INH and RIF, thus becoming eligible for the newer drug carrier in TB treatment.

Background: Antituberculosis drugs (ATDs) efficiently combat Mycobacterium tuberculosis either through direct molecular interactions or those of its metabolites. However, a variety of adverse effects have been reported, leading to frequent interruptions of treatment. To investigate the possible metabolic disturbances resulting from antituberculosis (TB) treatment, the uric acid (UA) level of patients on ATDs was measured in the southwest region of Cameroon. Methods: This hospital-based cross-sectional study involved 96 TB patients on ATDs and 32 controls who were neither on ATDs nor any other treatment that could increase UA levels. The hospital records of consenting participants were reviewed for medical history and questionnaires were issued. About 2 ml venous blood was collected and analyzed using spectrophotometers to determine UA levels. Results: Hyperuricemia was observed in 56/96 (58.3%) of the studied group as compared with 4/32 (12.5%) in the control group (P < 0.001). Our results indicated that treatment duration was significantly associated with hyperuricemia (P = 0.0016) while gender (P = 0.1275) was not. Conclusion: Hyperuricemia is associated with ATDs, with treatment duration being a significant factor. The disorder should be closely monitored, especially during the intensive phase of treatment.

This report describes the presence of cutaneous nodules and ulceration of the right leg of 1-year duration in an elderly woman. Prior biopsies had demonstrated dermal and subcutaneous granulomatous inflammation. Special stains for microorganisms and cultures were repeatedly negative. Polymerase chain reaction evaluation of the tissue block demonstrated the presence of Mycobacterium obuense.

Paradoxical reactions during tuberculosis (TB) treatment are well-described in the HIV seropositive population but less so in the HIV seronegative group. Abdominal TB rarely presents as spontaneous perforation; cases occurring during anti-TB therapy are even rarer. We describe the clinical progress of a case of an HIV-negative patient who developed acute peritonitis while on anti-TB treatment for peritoneal TB through a series of clinical, radiological and histological images. Visceral perforation can occur as a complication of TB treatment. A high index of suspicion with early surgical intervention is crucial in the management of such cases.

Type 2 leprosy reactions commonly known as erythema nodosum leprosum, but various clinical manifestations of type 2 leprosy reaction were exist. The highlight of this case series was to report various atypical clinical manifestations of type 2 leprosy reaction such as reactive perforating leprosy, erythema multiforme-like reaction, and sweet's syndrome (SS)-like reaction.

The diagnosis and treatment of tuberculosis (TB) in transplanted receivers presents several challenges. TB is an opportunistic infection with high morbidity and mortality in solid organs of transplanted patients, therefore, the diagnosis difficulties. A case of a 30-year-old male, heart transplanted patient, who after being submitted to mediastinoscopy, obtained a result of lymph node TB.

We report a case of an 88-year-old man with osteomyelitis of the right ankle, with histopathology demonstrating a Mycobacterium spindle cell pseudotumor. The Mycobacterium contained in this spindle cell pseudotumor was Mycobacterium chelonae. M. chelonae spindle cell pseudotumors are rare and have only been reported twice previously in the literature. Similarly, M. chelonae presenting as the pathogen in bone infection is rare. Due to this unusual presentation of M. chelonae, the antibiotic rationale was based largely on case reports and consisted of imipenem, clarithromycin, and linezolid. Antibiotic complications were experienced by the patient. Despite a renally adjusted dose of imipenem, the patient experienced imipenem toxicity and his antibiotics were modified to tigecycline and clarithromycin. Although his symptoms were clinically resolving, the patient sadly passed away before completing treatment.