Increase in acute pancreatitis, especially gallstone related, as the cause for emergency admissions: Temporal trend from Kashmir, India

BACKGROUND

The incidence of acute pancreatitis is increasing globally. Gallstones (GS) and ascariasis are the major causes for acute pancreatitis in the Kashmiri population. In recent years, we have observed an increase in the admission rate of acute pancreatitis. Many patients who present first time as gallstone pancreatitis have asymptomatic gallstones. We aimed at studying the etiology and yearly admission rate of acute pancreatitis with main focus on gallstone pancreatitis and the contribution of asymptomatic gallstones.

METHODS

This was a hospital-based, prospective, observational study from January 2015 to December 2019 for a period of five years. Patients of acute pancreatitis were evaluated for etiology and yearly admission rate. Patients of gallstone pancreatitis were evaluated in terms of clinical profile, risk factors, nature (symptomatic/asymptomatic, known/unknown gallstones), size of stones, treatment and outcome in terms of severity and mortality. The data was analyzed by Statistical Package for the Social Sciences (SPSS) version 20.0, as mean (SD), frequencies and percentages.

RESULTS

As many as 702 (8.5%) patients of acute pancreatitis were admitted among 8245 gastrointestinal emergencies in five years. The yearly admission rate of acute pancreatitis was 5.6%, 7.3%, 8.7%, 9.5% and 10.3%, respectively (p = 0.013). Gallstones, Ascariasis, alcohol and idiopathic acute pancreatitis were 47.7%, 6.9%, 1.2% and 33.7%, respectively. Gallstone pancreatitis increased from 31% in 2015 to 52.4% in 2019 (p = 0.045) and ascariasis-related acute pancreatitis declined from 14.4% to 1.6% (p = 0.034). Asymptomatic gallstones constituted 87.7% of cases. Known/unknown asymptomatic gallstones and symptomatic gallstones were 24.4%, 63.2% and 12.2%, respectively. Gallstones < 5 mm and > 5 mm were76.1% and 23.8% respectively (p = 0.027). Cholecystectomy rate in index admission was 4.7%. Mild, moderate and severe gallstone pancreatitis was 60.2%, 18.8% and 20.8%, respectively. Mortality in gallstone pancreatitis was 10.4%.

CONCLUSION

The incidence of acute pancreatitis is increasing due to gallstone pancreatitis. Ascariasis-related acute pancreatitis has declined. There is significant contribution of asymptomatic gallstones in patients who present for the first time as acute pancreatitis. Small gallstones < 5 mm are likely to be the risk factors for gallstone pancreatitis.

Mechanopathology of biofilm-like Mycobacterium tuberculosis cords

Mycobacterium tuberculosis (Mtb) cultured axenically without detergent forms biofilm-like cords, a clinical identifier of virulence. In lung-on-chip (LoC) and mouse models, cords in alveolar cells contribute to suppression of innate immune signaling via nuclear compression. Thereafter, extracellular cords cause contact-dependent phagocyte death but grow intercellularly between epithelial cells. The absence of these mechanopathological mechanisms explains the greater proportion of alveolar lesions with increased immune infiltration and dissemination defects in cording-deficient Mtb infections. Compression of Mtb lipid monolayers induces a phase transition that enables mechanical energy storage. Agent-based simulations demonstrate that the increased energy storage capacity is sufficient for the formation of cords that maintain structural integrity despite mechanical perturbation. Bacteria in cords remain translationally active despite antibiotic exposure and regrow rapidly upon cessation of treatment. This study provides a conceptual framework for the biophysics and function in tuberculosis infection and therapy of cord architectures independent of mechanisms ascribed to single bacteria.

Safety and efficacy of treatment for chronic hepatitis C during pregnancy: A prospective observational study in Srinagar, India

In India, the estimated prevalence of antenatal HCV infection is 0.3%-2.8%, and the rate of mother-to-child transmission has been estimated at 5%-15%. HCV treatment during pregnancy could reduce maternal complications from HCV infection, prevent transmission to the infant, and reduce HCV infection overall in women of childbearing age. However, there are limited studies of HCV treatment with direct-acting antiviral medications during pregnancy, and therefore, direct-acting antivirals are not commonly used for treatment during pregnancy. We describe our institutional experience in this prospective observational study over 3 years at the Sher-I-Kashmir Institute of Medical Sciences, Srinagar, India. Patients with chronic hepatitis C in pregnancy were enrolled and treated with ledipasvir and sofosbuvir after the first trimester. Primary end points were sustained virologic response at 12 weeks, adverse drug reactions, and congenital malformation of the infant. The secondary end point was the transmission of HCV infection to the infant. We enrolled 26 patients in our study. The mean age was 28 years (range of 21-36 y). All patients were noncirrhotic and treatment-naive. The mean HCV RNA before treatment was 9.2 ×10^5 IU/ml. Among the enrolled patients, 19 (73%) were genotype 3, 5 (19%) were genotype 1, and 2 (8%) were genotype 4. All patients achieved sustained virologic response at 12 weeks. Some patients reported nausea (27%), headache (27%), and fatigue (16%). All patients had institutional delivery, and no infant was found to have congenital malformations. No child had detectable HCV RNA at 6 months of age. To our knowledge, we here report results from the largest cohort of pregnant women treated for HCV infection globally. Ledipasvir and sofosbuvir were well tolerated and highly effective for both HCV cure in the mother and elimination of mother-to-child transmission. No congenital abnormalities were detected in our cohort. Elimination of mother-to-child transmission is urgently needed, and this study has shown that treatment of HCV during pregnancy may be a pragmatic approach for the greater benefit of both mother and the newborn.

Amidation of glutamate residues in mycobacterial peptidoglycan is essential for cell wall cross-linking

Introduction

Mycobacteria assemble a complex cell wall with cross-linked peptidoglycan (PG) which plays an essential role in maintenance of cell wall integrity and tolerance to osmotic pressure. We previously demonstrated that various hydrolytic enzymes are required to remodel PG during essential processes such as cell elongation and septal hydrolysis. Here, we explore the chemistry associated with PG cross-linking, specifically the requirement for amidation of the D-glutamate residue found in PG precursors.

Methods

Synthetic fluorescent probes were used to assess PG remodelling dynamics in live bacteria. Fluorescence microscopy was used to assess protein localization in live bacteria and CRISPR-interference was used to construct targeted gene knockdown strains. Time-lapse microscopy was used to assess bacterial growth. Western blotting was used to assess protein phosphorylation.

Results and discussion

In Mycobacterium smegmatis, we confirmed the essentiality for D-glutamate amidation in PG biosynthesis by labelling cells with synthetic fluorescent PG probes carrying amidation modifications. We also used CRISPRi targeted knockdown of genes encoding the MurT-GatD complex, previously implicated in D-glutamate amidation, and demonstrated that these genes are essential for mycobacterial growth. We show that MurT-rseGFP co-localizes with mRFP-GatD at the cell poles and septum, which are the sites of cell wall synthesis in mycobacteria. Furthermore, time-lapse microscopic analysis of MurT-rseGFP localization, in fluorescent D-amino acid (FDAA)-labelled mycobacterial cells during growth, demonstrated co-localization with maturing PG, suggestive of a role for PG amidation during PG remodelling and repair. Depletion of MurT and GatD caused reduced PG cross-linking and increased sensitivity to lysozyme and β-lactam antibiotics. Cell growth inhibition was found to be the result of a shutdown of PG biosynthesis mediated by the serine/threonine protein kinase B (PknB) which senses uncross-linked PG. Collectively, these data demonstrate the essentiality of D-glutamate amidation in mycobacterial PG precursors and highlight the MurT-GatD complex as a novel drug target.

Investigating the composition and recruitment of the mycobacterial ImuA'-ImuB-DnaE2 mutasome

A DNA damage-inducible mutagenic gene cassette has been implicated in the emergence of drug resistance in Mycobacterium tuberculosis during anti-tuberculosis (TB) chemotherapy. However, the molecular composition and operation of the encoded 'mycobacterial mutasome' - minimally comprising DnaE2 polymerase and ImuA' and ImuB accessory proteins - remain elusive. Following exposure of mycobacteria to DNA damaging agents, we observe that DnaE2 and ImuB co-localize with the DNA polymerase III β subunit (β clamp) in distinct intracellular foci. Notably, genetic inactivation of the mutasome in an imuBAAAAGG mutant containing a disrupted β clamp-binding motif abolishes ImuB-β clamp focus formation, a phenotype recapitulated pharmacologically by treating bacilli with griselimycin and in biochemical assays in which this β clamp-binding antibiotic collapses pre-formed ImuB-β clamp complexes. These observations establish the essentiality of the ImuB-β clamp interaction for mutagenic DNA repair in mycobacteria, identifying the mutasome as target for adjunctive therapeutics designed to protect anti-TB drugs against emerging resistance.

Clinical Profile, Etiology and Role of Endotherapy in Chronic Calcific Pancreatitis: An Experience from North India

Background: In recent years, we have witnessed an evolving landscape in the management of chronic pancreatitis (CP). Endoscopy plays a pivotal role in CP management. Because the management of CP is problematic, we aimed to review and evaluate the role of endoscopy in the management of CP. Methods: This study was carried out in patients with painful chronic calcific pancreatitis who were admitted to the Department of Gastroenterology at the Sher-I-Kashmir Institute of Medical Sciences (SKIMS), Srinagar. This was an observational prospective study. We included 67 patients with painful chronic calcific pancreatitis and pancreatic duct abnormalities (stones, strictures, or ductal variations) in our study. These patients had to access exocrine and endocrine status before any therapeutic measures. All the patients underwent endoscopic retrograde cholangiopancreatography (ERCP) as a therapeutic measure. After ERCP, the patients were followed up for 2 years to assess improvement in pain (visual analog scale score reduction), endocrine status (HBA1C reduction), or exocrine status (Fecal elastase reduction). Results: 67 patients were included in the study. Among them males were 32 (47.8%), females were 35(52.5%) and the age distribution studied were as in the age group of 15-30 years, patients were 23 (34.3%), in 30-45 years, there was 20 (29.9%), in age group of 45-60 year, patients were 20 (29.9%), and in the age group of 60-75 years, the patients were 4 (6%). Etiology was sought in all patients; alcohol-related CP was seen in three patients (4.5%), genetic in 11 (16.4%), IgG4 in one (1.5%), pancreatic divisum in 6 (9.0%), hyperparathyroidism in on1e (1.5%), and idiopathic in 45 (67.2%). All patients underwent ERCP for their symptoms to reduce ductal pressure, which is postulated as one of the hypotheses for pain in CP. Pancreatic duct (PD) clearance was attempted in all patients (complete in 42 [62.7%], partial in 17 [25.4%], and failed in 8 [11.9%]). These patients were followed for a period of two years after endotherapy, and the important predictors for pain reduction were single PD stones, disease in the head and body, and non-stricturing disease. Conclusion: Endotherapy offers a high rate of success in selected patients, clearance being better in distal disease and CP without PD strictures, suggesting early disease usually gets cleared very easily.

Mycobacterium tuberculosis and SARS-CoV-2 co-infections: The knowns and unknowns

Health impacts of Mycobacterium tuberculosis (Mtb) and SARS-CoV-2 co-infections are not fully understood. Both pathogens modulate host responses and induce immunopathology with extensive lung damage. With a quarter of the world's population harboring latent TB, exploring the relationship between SARS-CoV-2 infection and its effect on the transition of Mtb from latent to active form is paramount to control this pathogen. The effects of active Mtb infection on establishment and severity of COVID-19 are also unknown, despite the ability of TB to orchestrate profound long-lasting immunopathologies in the lungs. Absence of mechanistic studies and co-infection models hinder the development of effective interventions to reduce the health impacts of SARS-CoV-2 and Mtb co-infection. Here, we highlight dysregulated immune responses induced by SARS-CoV-2 and Mtb, their potential interplay, and implications for co-infection in the lungs. As both pathogens master immunomodulation, we discuss relevant converging and diverging immune-related pathways underlying SARS-CoV-2 and Mtb co-infections.

Uptake-independent killing of macrophages by extracellular Mycobacterium tuberculosis aggregates

Mycobacterium tuberculosis (Mtb) infection is initiated by inhalation of bacteria into lung alveoli, where they are phagocytosed by resident macrophages. Intracellular Mtb replication induces the death of the infected macrophages and the release of bacterial aggregates. Here, we show that these aggregates can evade phagocytosis by killing macrophages in a contact-dependent but uptake-independent manner. We use time-lapse fluorescence microscopy to show that contact with extracellular Mtb aggregates triggers macrophage plasma membrane perturbation, cytosolic calcium accumulation, and pyroptotic cell death. These effects depend on the Mtb ESX-1 secretion system, however, this system alone cannot induce calcium accumulation and macrophage death in the absence of the Mtb surface-exposed lipid phthiocerol dimycocerosate. Unexpectedly, we found that blocking ESX-1-mediated secretion of the EsxA/EsxB virulence factors does not eliminate the uptake-independent killing of macrophages and that the 50-kDa isoform of the ESX-1-secreted protein EspB can mediate killing in the absence of EsxA/EsxB secretion. Treatment with an ESX-1 inhibitor reduces uptake-independent killing of macrophages by Mtb aggregates, suggesting that novel therapies targeting this anti-phagocytic mechanism could prevent the propagation of extracellular bacteria within the lung.

Early invasion of the bladder wall by solitary bacteria protects UPEC from antibiotics and neutrophil swarms in an organoid model

Recurrence of uropathogenic Escherichia coli (UPEC) infections has been attributed to reactivation of quiescent intracellular reservoirs (QIRs) in deep layers of the bladder wall. QIRs are thought to arise late during infection following dispersal of bacteria from intracellular bacterial communities (IBCs) in superficial umbrella cells. Here, we track the formation of QIR-like bacteria in a bladder organoid model that recapitulates the stratified uroepithelium within a volume suitable for high-resolution live-cell imaging. Bacteria injected into the organoid lumen enter umbrella-like cells and proliferate to form IBC-like bodies. In parallel, single bacteria penetrate deeper layers of the organoid wall, where they localize within or between uroepithelial cells. These "solitary" bacteria evade killing by antibiotics and neutrophils and are morphologically distinct from bacteria in IBCs. We conclude that bacteria with QIR-like properties may arise at early stages of infection, independent of IBC formation and rupture.

Dynamic persistence of UPEC intracellular bacterial communities in a human bladder-chip model of urinary tract infection

Uropathogenic Escherichia coli (UPEC) proliferate within superficial bladder umbrella cells to form intracellular bacterial communities (IBCs) during early stages of urinary tract infections. However, the dynamic responses of IBCs to host stresses and antibiotic therapy are difficult to assess in situ. We develop a human bladder-chip model wherein umbrella cells and bladder microvascular endothelial cells are co-cultured under flow in urine and nutritive media respectively, and bladder filling and voiding mimicked mechanically by application and release of linear strain. Using time-lapse microscopy, we show that rapid recruitment of neutrophils from the vascular channel to sites of infection leads to swarm and neutrophil extracellular trap formation but does not prevent IBC formation. Subsequently, we tracked bacterial growth dynamics in individual IBCs through two cycles of antibiotic administration interspersed with recovery periods which revealed that the elimination of bacteria within IBCs by the antibiotic was delayed, and in some instances, did not occur at all. During the recovery period, rapid proliferation in a significant fraction of IBCs reseeded new foci of infection through bacterial shedding and host cell exfoliation. These insights reinforce a dynamic role for IBCs as harbors of bacterial persistence, with significant consequences for non-compliance with antibiotic regimens.

Urinary tract infections are one of the most common reasons people need antibiotics. These bacterial infections are typically caused by uropathogenic Escherichia coli (also known as UPEC), which either float freely in the urine and wash away when the bladder empties, or form communities inside cells that the bladder struggles to clear. It is possible that the bacteria living within cells are also more protected from the immune system and antibiotics. But this is hard to study in animal models.

To overcome this, Sharma et al. built a ‘bladder-chip’ which mimics the interface between the blood vessels and the tissue layers of the human bladder. Similar chip devices have also been made for other organs. However, until now, no such model had been developed for the bladder.

On the chip created by Sharma et al. is a layer of bladder cells which sit at the bottom of a channel filled with diluted human urine. These cells were infected with UPEC, and then imaged over time to see how the bacteria moved, interacted with the bladder cells, and aggregated together. Immune cells from human blood were then added to a vascular channel underneath the bladder tissue, which is coated with endothelial cells that normally line blood vessels. The immune cells rapidly crossed the endothelial barrier and entered the bladder tissue, and swarmed around sites of infection. In some instances, they released the contents of their cells to form net-like traps to catch the bacteria. But these traps failed to remove the bacteria living inside bladder cells.

Antibiotics were then added to the urine flowing over the bladder cells as well as the vascular channel, similar to how drugs would be delivered in live human tissue. Sharma et al. discovered that the antibiotics killed bacteria residing in bladder cells slower than bacteria floating freely in the urine. Furthermore, they found that bacteria living in tightly packed communities within bladder cells were more likely to survive treatment and go on to re-infect other parts of the tissue.

Antibiotic resistance is a pressing global challenge, and recurrent urinary tract infections are a significant contributor. The bladder-chip presented here could further our understanding of how these bacterial infections develop in vivo and how good antibiotics are at removing them. This could help researchers identify the best dosing and treatment strategies, as well as provide a platform for rapidly testing new antibiotic drugs and other therapies.

Rapid endotheliitis and vascular damage characterize SARS-CoV-2 infection in a human lung-on-chip model

Severe cases of SARS-CoV-2 infection are characterized by hypercoagulopathies and systemic endotheliitis of the lung microvasculature. The dynamics of vascular damage, and whether it is a direct consequence of endothelial infection or an indirect consequence of an immune cell-mediated cytokine storm remain unknown. Using a vascularized lung-on-chip model, we find that infection of alveolar epithelial cells leads to limited apical release of virions, consistent with reports of monoculture infection. However, viral RNA and proteins are rapidly detected in underlying endothelial cells, which are themselves refractory to apical infection in monocultures. Although endothelial infection is unproductive, it leads to the formation of cell clusters with low CD31 expression, a progressive loss of barrier integrity and a pro-coagulatory microenvironment. Viral RNA persists in individual cells generating an inflammatory response, which is transient in epithelial cells but persistent in endothelial cells and typified by IL-6 secretion even in the absence of immune cells. Inhibition of IL-6 signalling with tocilizumab reduces but does not prevent loss of barrier integrity. SARS-CoV-2-mediated endothelial cell damage thus occurs independently of cytokine storm.

A lung-on-chip model of early Mycobacterium tuberculosis infection reveals an essential role for alveolar epithelial cells in controlling bacterial growth

We establish a murine lung-on-chip infection model and use time-lapse imaging to reveal the dynamics of host-Mycobacterium tuberculosis interactions at an air-liquid interface with a spatiotemporal resolution unattainable in animal models and to probe the direct role of pulmonary surfactant in early infection. Surfactant deficiency results in rapid and uncontrolled bacterial growth in both macrophages and alveolar epithelial cells. In contrast, under normal surfactant levels, a significant fraction of intracellular bacteria are non-growing. The surfactant-deficient phenotype is rescued by exogenous addition of surfactant replacement formulations, which have no effect on bacterial viability in the absence of host cells. Surfactant partially removes virulence-associated lipids and proteins from the bacterial cell surface. Consistent with this mechanism, the attenuation of bacteria lacking the ESX-1 secretion system is independent of surfactant levels. These findings may partly explain why smokers and elderly persons with compromised surfactant function are at increased risk of developing active tuberculosis.

Tuberculosis is a contagious respiratory disease caused by the bacterium Mycobacterium tuberculosis. Droplets in the air carry these bacteria deep into the lungs, where they cling onto and infect lung cells. Only small droplets, holding one or two bacteria, can reach the right cells, which means that just a couple of bacterial cells can trigger an infection. But people respond differently to the bacteria: some develop active and fatal forms of tuberculosis, while many show no signs of infection. With no effective tuberculosis vaccine for adults, understanding why individuals respond differently to Mycobacterium tuberculosis may help develop treatments.

Different responses to Mycobacterium tuberculosis may stem from the earliest stages of infection, but these stages are difficult to study. For one thing, tracking the movements of the few bacterial cells that initiate infection is tricky. For another, studying the molecules, called ‘surfactants’, that the lungs produce to protect themselves from tuberculosis can prove difficult because these molecules are necessary for the lungs to inflate and deflate normally. Normally, the role of a molecule can be studied by genetically modifying an animal so it does not produce the molecule in question, which provides information as to its potential roles. Unfortunately, due to the role of surfactants in normal breathing, animals lacking them die. Therefore, to reveal the role of some of surfactants in tuberculosis, Thacker et al. used ‘lung-on-chip’ technology. The ‘chip’ (a transparent device made of a polymer compatible with biological tissues) is coated with layers of cells and has channels to simulate air and blood flow.

To see what effects surfactants have on M. tuberculosis bacteria, Thacker et al. altered the levels of surfactants produced by the cells on the lung-on-chip device. Two types of mouse cells were grown on the chip: lung cells and immune cells. When cells lacked surfactants, bacteria grew rapidly on both lung and immune cells, but when surfactants were present bacteria grew much slower on both cell types, or did not grow at all. Further probing showed that the surfactants pulled out proteins and fats on the surface of M. tuberculosis that help the bacteria to infect their host, highlighting the protective role of surfactants in tuberculosis.

These findings lay the foundations for a system to study respiratory infections without using animals. This will allow scientists to study the early stages of Mycobacterium tuberculosis infection, which is crucial for finding ways to manage tuberculosis.

Driving polar growth

Profiling the phenotype of 200,000 mutants revealed a new cofactor that may help a group of rod-shaped bacteria elongate and grow.

Genotype 1 and 3 Response to Velpatasvir and Sofosbuvir in Chronic Hepatitis C in the Kashmiri Population: An Observational Study

BACKGROUND

Our data is one of the earliest study from the Indian subcontinent on Velpatasvir/Sofosbuvir (VEL/SOF) combination in chronic hepatitis C (CHC). The primary end point was to evaluate sustained virologic response (SVR) 12 in CHC-infected patients and to determine its effect in patients with hepatitis C virus-related cirrhosis. The secondary end point was to observe any adverse events related to treatment.

METHODS

All patients with CHC were randomized into two groups: noncirrhotic and cirrhotic. The combination of VEL/SOF was given as recommended.

RESULTS

One hundred patients with CHC infection treated with the VEL/SOF regimen were evaluated. A total of 79 (79%) of 100 patients were noncirrhotic, and 21 (21%) were cirrhotic. We achieved SVR12 in 99 (99%) of 100 patients. Among cirrhotics, the mean serum bilirubin (mg/dl), albumin (g/dl), and platelet count (×10³/μL) improved from baseline 1.82 ± 0.87, 3.22 ± 0.69, and 80.19 ± 46.03 to 1.74 ± 0.87, 3.48 ± 0.72, and 85.05 ± 42.50, respectively, at SVR12 (P-value > 0.05). Mean serum alanine aminotransferase (ALT) (U/L) improved from baseline 71.28 ± 59.17 to 35.38 ± 17.39 at SVR12 (P-value < 0.024). Baseline mean liver stiffness measurement (LSM) in cirrhotic patients was 28.24 ± 10.87 kPa, which decreased to 24.04 ± 9.33 kPa at SVR12 (P-value, 0.02). The baseline Model for End-Stage Liver Disease (MELD) score was 13.47 ± 3.66, which decreased to 12.33 ± 5.46 at SVR12 (P-value, 0.28). The Child-Turcotte-Pugh score improved by 1 point in 33.33% (7/21) patients and 2 points in 9.52% (2/21) patients, and in the majority, that is, 38.09% (8/21), the score remained as it is.

CONCLUSION

A single daily dose of the tablet SOF/VEL combination is safe and effective in all types of CHC. There was a significant improvement in the mean transaminase level and LSM at SVR12. And the MELD score improved by 1 point at SVR12 among cirrhotics.

Preexisting variation in DNA damage response predicts the fate of single mycobacteria under stress

Clonal microbial populations are inherently heterogeneous, and this diversification is often considered as an adaptation strategy. In clinical infections, phenotypic diversity is found to be associated with drug tolerance, which in turn could evolve into genetic resistance. Mycobacterium tuberculosis, which ranks among the top ten causes of mortality with high incidence of drug-resistant infections, exhibits considerable phenotypic diversity. In this study, we quantitatively analyze the cellular dynamics of DNA damage responses in mycobacteria using microfluidics and live-cell fluorescence imaging. We show that individual cells growing under optimal conditions experience sporadic DNA-damaging events manifested by RecA expression pulses. Single-cell responses to these events occur as transient pulses of fluorescence expression, which are dependent on the gene-network structure but are triggered by extrinsic signals. We demonstrate that preexisting subpopulations, with discrete levels of DNA damage response, are associated with differential susceptibility to fluoroquinolones. Our findings reveal that the extent of DNA integrity prior to drug exposure impacts the drug activity against mycobacteria, with conceivable therapeutic implications.

Fluorescent Benzothiazinone Analogues Efficiently and Selectively Label Dpre1 in Mycobacteria and Actinobacteria

Benzothiazinones (BTZ) are highly potent bactericidal inhibitors of mycobacteria and the lead compound, BTZ043, and the optimized drug candidate, PBTZ169, have potential for the treatment of tuberculosis. Here, we exploited the tractability of the BTZ scaffold by attaching a range of fluorophores to the 2-substituent of the BTZ ring via short linkers. We show by means of fluorescence imaging that the most advanced derivative, JN108, is capable of efficiently labeling its target, the essential flavoenzyme DprE1, both in cell-free extracts and after purification as well as in growing cells of different actinobacterial species. DprE1 displays a polar localization in Mycobacterium tuberculosis, M. marinum, M. smegmatis, and Nocardia farcinica but not in Corynebacterium glutamicum. Finally, mutation of the cysteine residue in DprE1 in these species, to which BTZ covalently binds, abolishes completely the interaction with JN108, thereby highlighting the specificity of this fluorescent probe.

Elucidating the role of (p)ppGpp in mycobacterial persistence against antibiotics

Bacterial persistence, the ability of bacteria to survive high concentrations of antibiotics for extended periods of time, is an important contributing factor to therapy failure and development of chronic and recurrent infections. Several recent studies have suggested that this persistence is mediated primarily by (p)ppGpp, through its interactions with toxin-antitoxin modules and polyphosphates. In this study, we address whether these key players play a role in mycobacterial persistence against antibiotics. We targeted these specific pathways in Mycobacterium smegmatis by constructing deletion strains of (p)ppGpp synthetase/hydrolase (relA), polyphosphate kinases (ppk1 and ppk2), exopolyphosphatases (ppx1 and ppx2), and the lon protease. None of these mutant strains exhibited altered levels of persisters against isoniazid and ciprofloxacin, when compared with wild-type strain. Even under conditions in which the stringent response usually gets activated, these strains displayed wild-type persister levels. Interestingly, we also found that unlike Escherichia coli, maintaining M. smegmatis in exponential phase by repeated passaging does not eliminate persisters suggesting that at least against the antibiotics tested, stationary-phase dependent persisters (type I) are not the major contributors. Thus, our data demonstrate that multiple mechanisms of antibiotic persistence exist and that these vary widely among different bacterial species. © 2018 IUBMB Life, 70(9):836-844, 2018.

Division site selection linked to inherited cell surface wave troughs in mycobacteria

Cell division is tightly controlled in space and time to maintain cell size and ploidy within narrow bounds. In bacteria, the canonical Minicell (Min) and nucleoid occlusion (Noc) systems together ensure that division is restricted to midcell after completion of chromosome segregation¹. It is unknown how division site selection is controlled in bacteria that lack homologues of the Min and Noc proteins, including mycobacteria responsible for tuberculosis and other chronic infections². Here, we use correlated optical and atomic-force microscopy^3,4 to demonstrate that morphological landmarks (waveform troughs) on the undulating surface of mycobacterial cells correspond to future sites of cell division. Newborn cells inherit wave troughs from the (grand)mother cell and ultimately divide at the centre-most wave trough, making these morphological features the earliest known landmark of future division sites. In cells lacking the chromosome partitioning (Par) system, missegregation of chromosomes is accompanied by asymmetric cell division at off-centre wave troughs, resulting in the formation of anucleate cells. These results demonstrate that inherited morphological landmarks and chromosome positioning together restrict mycobacterial division to the midcell position.

The Inosine Monophosphate Dehydrogenase, GuaB2, Is a Vulnerable New Bactericidal Drug Target for Tuberculosis

VCC234718, a molecule with growth inhibitory activity against Mycobacterium tuberculosis (Mtb), was identified by phenotypic screening of a 15344-compound library. Sequencing of a VCC234718-resistant mutant identified a Y487C substitution in the inosine monophosphate dehydrogenase, GuaB2, which was subsequently validated to be the primary molecular target of VCC234718 in Mtb. VCC234718 inhibits Mtb GuaB2 with a Ki of 100 nM and is uncompetitive with respect to IMP and NAD+. This compound binds at the NAD+ site, after IMP has bound, and makes direct interactions with IMP; therefore, the inhibitor is by definition uncompetitive. VCC234718 forms strong pi interactions with the Y487 residue side chain from the adjacent protomer in the tetramer, explaining the resistance-conferring mutation. In addition to sensitizing Mtb to VCC234718, depletion of GuaB2 was bactericidal in Mtb in vitro and in macrophages. When supplied at a high concentration (≥125 μM), guanine alleviated the toxicity of VCC234718 treatment or GuaB2 depletion via purine salvage. However, transcriptional silencing of guaB2 prevented Mtb from establishing an infection in mice, confirming that Mtb has limited access to guanine in this animal model. Together, these data provide compelling validation of GuaB2 as a new tuberculosis drug target.

Identification of aminopyrimidine-sulfonamides as potent modulators of Wag31-mediated cell elongation in mycobacteria

There is an urgent need to discover new anti-tubercular agents with novel mechanisms of action in order to tackle the scourge of drug-resistant tuberculosis. Here, we report the identification of such a molecule - an AminoPYrimidine-Sulfonamide (APYS1) that has potent, bactericidal activity against M. tuberculosis. Mutations in APYS1-resistant M. tuberculosis mapped exclusively to wag31, a gene that encodes a scaffolding protein thought to orchestrate cell elongation. Recombineering confirmed that a Gln201Arg mutation in Wag31 was sufficient to cause resistance to APYS1, however, neither overexpression nor conditional depletion of wag31 impacted M. tuberculosis susceptibility to this compound. In contrast, expression of the wildtype allele of wag31 in APYS1-resistant M. tuberculosis was dominant and restored susceptibility to APYS1 to wildtype levels. Time-lapse imaging and scanning electron microscopy revealed that APYS1 caused gross malformation of the old pole of M. tuberculosis, with eventual lysis. These effects resembled the morphological changes observed following transcriptional silencing of wag31 in M. tuberculosis. These data show that Wag31 is likely not the direct target of APYS1, but the striking phenotypic similarity between APYS1 exposure and genetic depletion of Wag31 in M. tuberculosis suggests that APYS1 might indirectly affect Wag31 through an as yet unknown mechanism.

Antitubercular drugs for an old target: GSK693 as a promising InhA direct inhibitor

Despite being one of the first antitubercular agents identified, isoniazid (INH) is still the most prescribed drug for prophylaxis and tuberculosis (TB) treatment and, together with rifampicin, the pillars of current chemotherapy. A high percentage of isoniazid resistance is linked to mutations in the pro-drug activating enzyme KatG, so the discovery of direct inhibitors (DI) of the enoyl-ACP reductase (InhA) has been pursued by many groups leading to the identification of different enzyme inhibitors, active against Mycobacterium tuberculosis (Mtb), but with poor physicochemical properties to be considered as preclinical candidates. Here, we present a series of InhA DI active against multidrug (MDR) and extensively (XDR) drug-resistant clinical isolates as well as in TB murine models when orally dosed that can be a promising foundation for a future treatment.

Whole Cell Target Engagement Identifies Novel Inhibitors of Mycobacterium tuberculosis Decaprenylphosphoryl-β-d-ribose Oxidase

We have targeted the Mycobacterium tuberculosis decaprenylphosphoryl-β-d-ribose oxidase (Mt-DprE1) for potential chemotherapeutic intervention of tuberculosis. A multicopy suppression strategy that overexpressed Mt-DprE1 in M. bovis BCG was used to profile the publically available GlaxoSmithKline antimycobacterial compound set, and one compound (GSK710) was identified that showed an 8-fold higher minimum inhibitory concentration relative to the control strain. Analogues of GSK710 show a clear relationship between whole cell potency and in vitro activity using an enzymatic assay employing recombinant Mt-DprE1, with binding affinity measured by fluorescence quenching of the flavin cofactor of the enzyme. M. bovis BCG spontaneous resistant mutants to GSK710 and a closely related analogue were isolated and sequencing of ten such mutants revealed a single point mutation at two sites, E221Q or G248S within DprE1, providing further evidence that DprE1 is the main target of these compounds. Finally, time-lapse microscopy experiments showed that exposure of M. tuberculosis to a compound of this series arrests bacterial growth rapidly followed by a slower cytolysis phase.

A Comprehensive Study on Mo/CdTe Metal-Semiconductor Interface Deposited by Radio Frequency Magnetron Sputtering

Metal-semiconductor (MS) junction between Mo and CdTe, which is one of the fundamental issues for CdTe based solar cell, has been investigated for films deposited on different substrates. XRD pattern of Mo/CdTe films on the polyimide (PI) substrate shows a strong preferential orientation of MoTe2 in (100) at 2θ = 29.44 degrees, which becomes less apparent as deposition time of CdTe increases. However, on soda lime glass (SLG) no such XRD reflection pattern is observed. Moreover, from EDX measurement, Mo-Te compound also identifies MoTe2 at Mo/CdTe interface on PI substrate, which is not present on SLG. Bulk carrier concentration of Mo/CdTe films on PI substrate for lower deposition time of CdTe is found 1.42 x 10(18) cm(-3), which is almost equal to MoTe2. Thereafter, it decreases as CdTe growth time increases. The type of unintentionally formed MoTe2 on PI substrate is found to be n-type in nature. Lattice constants of a = 6.5 Å for CdTe and a = 3.52 Å for MoTe2 are found from nanostructure study by TEM.

2-Carboxyquinoxalines kill mycobacterium tuberculosis through noncovalent inhibition of DprE1

Phenotypic screening of a quinoxaline library against replicating Mycobacterium tuberculosis led to the identification of lead compound Ty38c (3-((4-methoxybenzyl)amino)-6-(trifluoromethyl)quinoxaline-2-carboxylic acid). With an MIC99 and MBC of 3.1 μM, Ty38c is bactericidal and active against intracellular bacteria. To investigate its mechanism of action, we isolated mutants resistant to Ty38c and sequenced their genomes. Mutations were found in rv3405c, coding for the transcriptional repressor of the divergently expressed rv3406 gene. Biochemical studies clearly showed that Rv3406 decarboxylates Ty38c into its inactive keto metabolite. The actual target was then identified by isolating Ty38c-resistant mutants of an M. tuberculosis strain lacking rv3406. Here, mutations were found in dprE1, encoding the decaprenylphosphoryl-d-ribose oxidase DprE1, essential for biogenesis of the mycobacterial cell wall. Genetics, biochemical validation, and X-ray crystallography revealed Ty38c to be a noncovalent, noncompetitive DprE1 inhibitor. Structure-activity relationship studies generated a family of DprE1 inhibitors with a range of IC50's and bactericidal activity. Co-crystal structures of DprE1 in complex with eight different quinoxaline analogs provided a high-resolution interaction map of the active site of this extremely vulnerable target in M. tuberculosis.

Single-cell analysis of mycobacteria using microfluidics and time-lapse microscopy

The crucial role of phenotypic heterogeneity in bacterial physiology and adaptive responses has required the introduction of new ways to investigate bacterial individuality. Time-lapse microscopy is a powerful technique for evaluating phenotypic diversity in bacteria at the single-cell level, whether exploring the dynamics of gene expression and protein localization or characterizing the heterogeneous phenotypic response to perturbations. Here, we present protocols to carry out time-lapse imaging of mycobacteria at the single-cell level using either agarose pads or customized microfluidic devices. The sequences of images obtained can be analyzed using programs such as ImageJ and allow the investigator not only to extract various parameters of growth and gene expression dynamics but also to unravel the physiological basis behind phenomenon such as persistence against stresses.

EspI regulates the ESX-1 secretion system in response to ATP levels in Mycobacterium tuberculosis

The function of EspI, a 70 kDa protein in Mycobacterium tuberculosis, has remained unclear. Although EspI is encoded by a gene within the esx-1 locus, in this study we clarify previous conflicting results and show that EspI is not essential for ESX-1-mediated secretion or virulence in M. tuberculosis. We also provide evidence that reduction of cellular ATP levels in wild-type M. tuberculosis using the drug bedaquiline completely blocks ESX-1-mediated secretion. Remarkably, M. tuberculosis lacking EspI fails to exhibit this phenotype. Furthermore, mutagenesis of a highly conserved ATP-binding motif in EspI renders M. tuberculosis incapable of shutting down ESX-1-mediated secretion during ATP depletion. Collectively these results show that M. tuberculosis EspI negatively regulates the ESX-1 secretion system in response to low cellular ATP levels and this function requires the ATP-binding motif. In light of our results the potential significance of EspI in ESX-1 function during latent tuberculosis infection and reactivation is also discussed.

Dielectrophoresis-based purification of antibiotic-treated bacterial subpopulations

Persistence of bacteria during antibiotic therapy is a widespread phenomenon, of particular importance in refractory mycobacterial infections such as leprosy and tuberculosis. Persistence is characterized by the phenotypic tolerance of a subpopulation of bacterial cells to antibiotics. Characterization of these "persister" cells is often difficult due to the transient, non-heritable nature of the phenotype and due to the presence of contaminating material from non-persisting cells, which usually comprise the larger fraction. In this study, we use 3D carbon-electrode arrays for dielectrophoresis-based separation of intact cells from damaged cells, revealed by differential staining with propidium iodide, and we use this procedure to purify intact cells from cultures of Mycobacterium smegmatis treated with isoniazid, a frontline anti-tuberculosis drug. The method presented in this study could be used for rapid label-free enrichment of intact persister cells from antibiotic-treated cultures while preserving the metastable persister phenotype. This approach would facilitate the downstream analysis of low-frequency subpopulations of cells using conventional omics techniques, such as transcriptomic and proteomic analysis.

Assessing the essentiality of the decaprenyl-phospho-d-arabinofuranose pathway in Mycobacterium tuberculosis using conditional mutants

In Mycobacterium tuberculosis the decaprenyl-phospho-d-arabinofuranose (DPA) pathway is a validated target for the drugs ethambutol and benzothiazinones. To identify other potential drug targets in the pathway, we generated conditional knock-down mutants of each gene involved using the TET-PIP OFF system. dprE1, dprE2, ubiA, prsA, rv2361c, tkt and rpiB were confirmed to be essential under non-permissive conditions, whereas rv3807c was not required for survival. In the most vulnerable group, DprE1-depleted cells died faster in vitro and intracellularly than those lacking UbiA and PrsA. Downregulation of DprE1 and UbiA resulted in similar phenotypes, namely swelling of the bacteria, cell wall damage and lysis as observed at the single cell level, by real time microscopy and electron microscopy. By contrast, depletion of PrsA led to cell elongation and implosion, which was suggestive of a more pleiotropic effect. Drug sensitivity assays with known DPA-inhibitors supported the use of conditional knock-down strains for target-based whole-cell screens. Together, our work provides strong evidence for the vulnerability of all but one of the enzymes in the DPA pathway and generates valuable tools for the identification of lead compounds targeting the different biosynthetic steps. PrsA, phosphoribosyl-pyrophosphate synthetase, appears to be a particularly attractive new target for drug discovery.

Delayed bactericidal response of Mycobacterium tuberculosis to bedaquiline involves remodelling of bacterial metabolism

Bedaquiline (BDQ), an ATP synthase inhibitor, is the first drug to be approved for treatment of multidrug-resistant tuberculosis in decades. Though BDQ has shown excellent efficacy in clinical trials, its early bactericidal activity during the first week of chemotherapy is minimal. Here, using microfluidic devices and time-lapse microscopy of Mycobacterium tuberculosis, we confirm the absence of significant bacteriolytic activity during the first 3-4 days of exposure to BDQ. BDQ-induced inhibition of ATP synthesis leads to bacteriostasis within hours after drug addition. Transcriptional and proteomic analyses reveal that M. tuberculosis responds to BDQ by induction of the dormancy regulon and activation of ATP-generating pathways, thereby maintaining bacterial viability during initial drug exposure. BDQ-induced bacterial killing is significantly enhanced when the mycobacteria are grown on non-fermentable energy sources such as lipids (impeding ATP synthesis via glycolysis). Our results show that BDQ exposure triggers a metabolic remodelling in mycobacteria, thereby enabling transient bacterial survival.

Mycobacterium tuberculosis EspB binds phospholipids and mediates EsxA-independent virulence

The type-VII ESX-1 secretion apparatus, encoded by the esx-1 genetic locus, is essential for the export of EsxA and EsxB, two major virulence factors of Mycobacterium tuberculosis. ESX-1 also requires the products of the unlinked espACD operon for optimal function and these proteins are considered integral parts of the secretion apparatus. Here we show that the espACD operon is not necessary for the secretion of EspB, another ESX-1 substrate, and this unimpeded secretion of EspB is associated with significant residual virulence. Upon further investigation, we found that purified EspB can facilitate M. tb virulence even in the absence of EsxA and EsxB, and may do so by binding the bioactive phospholipids phosphatidic acid and phosphatidylserine, both of which are potent bioactive molecules with prominent roles in eukaryotic cell signalling. Our findings provide new insights into the impact of the espACD operon on the ESX-1 apparatus and reveal a distinct virulence function for EspB with novel implications in M. tb-host interactions.

Structural basis for benzothiazinone-mediated killing of Mycobacterium tuberculosis

The benzothiazinone BTZ043 is a tuberculosis drug candidate with nanomolar whole-cell activity. BTZ043 targets the DprE1 catalytic component of the essential enzyme decaprenylphosphoryl-β-D-ribofuranose-2'-epimerase, thus blocking biosynthesis of arabinans, vital components of mycobacterial cell walls. Crystal structures of DprE1, in its native form and in a complex with BTZ043, reveal formation of a semimercaptal adduct between the drug and an active-site cysteine, as well as contacts to a neighboring catalytic lysine residue. Kinetic studies confirm that BTZ043 is a mechanism-based, covalent inhibitor. This explains the exquisite potency of BTZ043, which, when fluorescently labeled, localizes DprE1 at the poles of growing bacteria. Menaquinone can reoxidize the flavin adenine dinucleotide cofactor in DprE1 and may be the natural electron acceptor for this reaction in the mycobacterium. Our structural and kinetic analysis provides both insight into a critical epimerization reaction and a platform for structure-based design of improved inhibitors.

Dynamic persistence of antibiotic-stressed mycobacteria

Exposure of an isogenic bacterial population to a cidal antibiotic typically fails to eliminate a small fraction of refractory cells. Historically, fractional killing has been attributed to infrequently dividing or nondividing "persisters." Using microfluidic cultures and time-lapse microscopy, we found that Mycobacterium smegmatis persists by dividing in the presence of the drug isoniazid (INH). Although persistence in these studies was characterized by stable numbers of cells, this apparent stability was actually a dynamic state of balanced division and death. Single cells expressed catalase-peroxidase (KatG), which activates INH, in stochastic pulses that were negatively correlated with cell survival. These behaviors may reflect epigenetic effects, because KatG pulsing and death were correlated between sibling cells. Selection of lineages characterized by infrequent KatG pulsing could allow nonresponsive adaptation during prolonged drug exposure.

Nanoparticle conjugation and pulmonary delivery enhance the protective efficacy of Ag85B and CpG against tuberculosis

Vaccines that drive robust T-cell immunity against Mycobacterium tuberculosis (Mtb) are needed both for prophylactic and therapeutic purposes. We have recently developed a synthetic vaccine delivery platform with Pluronic-stabilized polypropylene sulfide nanoparticles (NPs), which target lymphoid tissues by their small size (∼ 30 nm) and which activate the complement cascade by their surface chemistry. Here we conjugated the tuberculosis antigen Ag85B to the NPs (NP-Ag85B) and compared their efficacy in eliciting relevant immune responses in mice after intradermal or pulmonary administration. Pulmonary administration of NP-Ag85B with the adjuvant CpG led to enhanced induction of antigen-specific polyfunctional Th1 responses in the spleen, the lung and lung-draining lymph nodes as compared to soluble Ag85B with CpG and to the intradermally-delivered formulations. Mucosal and systemic Th17 responses were also observed with this adjuvanted NP formulation and vaccination route, especially in the lung. We then evaluated protection induced by the adjuvanted NP formulation following a Mtb aerosol challenge and found that vaccination with NP-Ag85B and CpG via the pulmonary route displayed a substantial reduction of the lung bacterial burden, both compared to soluble Ag85B with CpG and to the corresponding intradermally delivered formulations. These findings highlight the potential of administrating NP-based formulations by the pulmonary route for TB vaccination.

Development of a repressible mycobacterial promoter system based on two transcriptional repressors

Tightly regulated gene expression systems represent invaluable tools for studying gene function and for the validation of drug targets in bacteria. While several regulated bacterial promoters have been characterized, few of them have been successfully used in mycobacteria. In this article we describe the development of a novel repressible promoter system effective in both fast- and slow-growing mycobacteria based on two chromosomally encoded repressors, dependent on tetracycline (TetR) and pristinamycin (Pip), respectively. This uniqueness results in high versatility and stringency. Using this method we were able to obtain an ftsZ conditional mutant in Mycobacterium smegmatis and a fadD32 conditional mutant in Mycobacterium tuberculosis, confirming their essentiality for bacterial growth in vitro. This repressible promoter system could also be exploited to regulate gene expression during M. tuberculosis intracellular growth.

Boosting with a DNA vaccine expressing ESAT-6 (DNAE6) obliterates the protection imparted by recombinant BCG (rBCGE6) against aerosol Mycobacterium tuberculosis infection in guinea pigs

Owing to its highly immunodominant nature and ability to induce long-lived memory immunity, ESAT-6, a prominent antigen of Mycobacterium tuberculosis, has been employed in several approaches to develop tuberculosis vaccines. Here, for the first time, we combined ESAT-6 based recombinant BCG (rBCG) and DNA vaccine (DNAE6) in a prime boost approach. Interestingly, in spite of inducing an enhanced antigen specific IFN-gamma response in mice, a DNAE6 booster completely obliterated the protection imparted by rBCG against tuberculosis in guinea pigs. Analysis of immunopathology and cytokine responses suggests involvement of an exaggerated immunity behind the lack of protection imparted by this regimen.

Assessment of utilization of untied fund provided under the national rural health mission in Uttar Pradesh

OBJECTIVES

To seek opinion regarding the procurement and spending of untied fund provided to health centers and Village Health and Sanitation Committees (VHSCs) in selected districts in the state of Uttar Pradesh.

METHODS

It was a cross sectional descriptive study conducted during September-December 2008. The multi-stage random sampling technique was adopted to select the districts, health facilities and VHSCs. The data was collected using semi structured interview schedule, Focus Group Discussions (FGDs) with ANMs for qualitative information, review of the records of health centers and VHSCs.

RESULTS

The concept of untied fund was perceived to be a very good one at all levels. Guideline for utilization of untied fund was either not available or if available, was not clear to concerned personnel. The decision of expenditure of untied funds of CHCs and PHCs was taken in the meeting of Rogi Kalyan Samiti (RKS), but members from other sectors such as PRI, education, revenue department etc. usually did not attend the meeting. Most of Medical Officer in charges (MOICs) were not aware regarding availability of untied fund. About 50% of ANMs were not able to expend the money due to non co-operation of Pradhan. In majority of the cases the decision regarding the utilization of untied fund was taken by ANM herself instead of VHSC meeting.

CONCLUSION

Regular update and orientation to the service providers about the untied fund and its efficient utilization, strict monitoring of utilization of untied fund at each and every level is needed.

Indigenous system of medicine lady doctors and general nurse midwives in operationalization of 24 x 7 services under NRHM in selected districts of Uttar Pradesh

OBJECTIVES

To find out the status of utilization of MCH services after the induction of the indigenous system of medicine (ISM) lady doctors and CNMs for 24 x 7 services and the acceptance of this innovation by the health system and the community.

METHODS

This was a cross-sectional descriptive study conducted during October to November 2008 in 10 blocks of 5 selected districts in Uttar Pradesh. Study subjects (CMO, MO I/C, ISM lady doctors, GNMs, PRI members) were interviewed and FGDs were also conducted.

RESULTS

Shortages of medical and paramedical staff as well as facilities for institutional delivery at the district and block level were revealed. Only 6 out of 16 ISMs were trained. Knowledge of the ISMs/GNMs was lacking in many essential components of MCH including identifying high-risk pregnancy, high-risk newborn for urgent and timely referral. 36% could identify high-risk pregnancy and only 18% used partograph during labour. About 68% of the ISMs/GNMs were dissatisfied regarding honorarium, 59% with work conditions and 55% with delivery instrument. Induction of ISMs/GNMs were welcomed and accepted by medical officers and panchayets. Delay in payment of honorarium and pay disparity between MBBS doctors and ISM lady doctors and lack of proper logistic support were some of the problems facing the ISMs/GNMs.

CONCLUSION

For sustenance, in service training, provision of transport and accommodation, logistic support, well equipped labour room, timely monitoring and supervision, removal of pay disparities need to be ensured. The contractual appointment should also be made permanent and lucrative.

An assessment of functioning of mobile medical units in Jharkhand

BACKGROUND & OBJECTIVE

A scheme of Mobile Medical Units (MMUs) has been initiated under NRHM in Jharkhand state from the year 2008 in an effort to take healthcare to doorstep of the public in rural areas, especially in underserved areas. The objective of the study was to assess the functioning of Medical Mobile Units in Jharkhand through rapid assessment mode.

METHODS

A cross sectional descriptive study was conducted in three selected districts of Jharkhand state during September-December 2008. Data was collected through in-depth interview using semistructured schedules with State Programme Managers, Chief Medical Officers, District programme managers, staff of MMU and beneficiaries.

RESULTS

The scheme provided curative and diagnostic facilities like X-ray, ultra sound, and blood test to the poor and under-served areas. More than 90% of clients reported availability of medicines in MMUs. However, more than 90% of them had no prior information about the day and time of visits by the MMUs. Some of the operational difficulties being faced by the scheme were reported to be vibrations of generator disturbing the lab investigations, poor condition of the road, unwillingness of doctors to go in far-off areas and heavy workload.

CONCLUSION

The scheme of MMUs has been successful in providing health services to the poor and under-served areas.

Benzothiazinones kill Mycobacterium tuberculosis by blocking arabinan synthesis

New drugs are required to counter the tuberculosis (TB) pandemic. Here, we describe the synthesis and characterization of 1,3-benzothiazin-4-ones (BTZs), a new class of antimycobacterial agents that kill Mycobacterium tuberculosis in vitro, ex vivo, and in mouse models of TB. Using genetics and biochemistry, we identified the enzyme decaprenylphosphoryl-beta-d-ribose 2'-epimerase as a major BTZ target. Inhibition of this enzymatic activity abolishes the formation of decaprenylphosphoryl arabinose, a key precursor that is required for the synthesis of the cell-wall arabinans, thus provoking cell lysis and bacterial death. The most advanced compound, BTZ043, is a candidate for inclusion in combination therapies for both drug-sensitive and extensively drug-resistant TB.

Enhanced and enduring protection against tuberculosis by recombinant BCG-Ag85C and its association with modulation of cytokine profile in lung

Background

The variable efficacy (0–80%) of Mycobacterium bovis Bacille Calmette Guréin (BCG) vaccine against adult tuberculosis (TB) necessitates development of alternative vaccine candidates. Development of recombinant BCG (rBCG) over-expressing promising immunodominant antigens of M. tuberculosis represents one of the potential approaches for the development of vaccines against TB.

Methods/Principal Findings

A recombinant strain of BCG - rBCG85C, over expressing the antigen 85C, a secretory immuno-dominant protein of M. tuberculosis, was evaluated for its protective efficacy in guinea pigs against M. tuberculosis challenge by aerosol route. Immunization with rBCG85C resulted in a substantial reduction in the lung (1.87 log₁₀, p<0.01) and spleen (2.36 log₁₀, p<0.001) bacillary load with a commensurate reduction in pathological damage, when compared to the animals immunized with the parent BCG strain at 10 weeks post-infection. rBCG85C continued to provide superior protection over BCG even when post-challenge period was prolonged to 16 weeks. The cytokine profile of pulmonary granulomas revealed that the superior protection imparted by rBCG85C was associated with the reduced levels of pro-inflammatory cytokines - interleukin (IL)-12, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, moderate levels of anti-inflammatory cytokine - transforming growth factor (TGF)-β along with up-regulation of inducible nitric oxide synthase (iNOS). In addition, the rBCG85C vaccine induced modulation of the cytokine levels was found to be associated with reduced fibrosis and antigen load accompanied by the restoration of normal lung architecture.

Conclusions/Significance

These results clearly indicate the superiority of rBCG85C over BCG as a promising prophylactic vaccine against TB. The enduring protection observed in this study gives enough reason to postulate that if an open-ended study is carried out with low dose of infection, rBCG85C vaccine in all likelihood would show enhanced survival of guinea pigs.

Microbial phenotypic heterogeneity and antibiotic tolerance

Phenotypic heterogeneity, defined as metastable variation in cellular parameters generated by epigenetic mechanisms, is crucial for the persistence of bacterial populations under fluctuating selective pressures. Diversity ensures that some individuals will survive a potentially lethal stress, such as an antibiotic, that would otherwise obliterate the entire population. The refractoriness of bacterial infections to antibiotic therapy has been ascribed to antibiotic-tolerant variants known as 'persisters'. The persisters are not drug-resistant mutants and it is unclear why they survive antibiotic pressure that kills their genetically identical siblings. Recent conceptual and technological advances are beginning to yield some surprising new insights into the mechanistic basis of this clinically important manifestation of phenotypic heterogeneity.

Elicitation of efficient, protective immune responses by using DNA vaccines against tuberculosis

DNA vaccination is an effective method for elicitation of strong humoral as well as cellular immune responses. DNA vaccines expressing mycobacterial antigens ESAT-6 (Rv3875), alpha-crystallin (Rv2031c) and superoxide dismutase A (Rv3846) were evaluated for their immune responses in Balb/c mice and protective efficacy in guinea pigs. Immunization of mice with the DNA vaccines expressing superoxide dismutase A and alpha-crystallin resulted in markedly higher levels of IFN-gamma as compared to the levels of IL-10. The DNA vaccine expressing ESAT-6 elicited a mixed Th1/Th2 response. Immunization of guinea pigs with these DNA vaccines and subsequent challenge of animals with Mycobacterium tuberculosis H(37)Rv, showed that DNA vaccine expressing superoxide dismutase imparted the maximum protection as observed by a 50 and 10 folds reduction in bacillary load in spleens and lungs, respectively, in comparison to immunization with vector control.