Current approaches to tuberculosis in the United States

An early and trustable indicator suggestive of non-tuberculosis mycobacteria isolation in a high tuberculosis burden setting

BACKGROUND

Distinguishing between nontuberculous mycobacterial (NTM) lung infections and pulmonary tuberculosis becomes challenging due to their similar clinical manifestations and radiological images. Consequently, instances of delayed diagnosis or misdiagnosis are highly frequent. A feasible and reliable indicator of the existence of NTM in the early stages of the disease would help to solve this dilemma.

METHODS

In this study, we evaluated the potential of smear-positive and Xpert assay (Cepheid, USA) negative outcomes as an early indicator of possible NTM infection in a high TB-burden setting retrospectively and prospectively.

RESULTS

During the study period, 12·77% (138/1081) of the smear-positive cases yielded negative outcomes with the simultaneous Xpert assay. From the 110 patients who yielded smear-positive/Xpert-negative outcomes and cultivated strain as well, 105 (95·45%) were proved to have NTM isolated. By incorporating an additional criterion of a negative result from the Interferon-gamma release assay, the accuracy of the screening method reached 100%. Regarding the NTM presence prediction value, smear-positive/Xpert-negative has a sensitivity of 24·86% (45/181) in all NTM isolated cases but 93·75-96·55% accuracy in retrospective study or 93·75% accuracy in prospective study in smear-positive NTM isolated cases. In addition, the specificity was ∼99·47% (943/948) in smear-positive tuberculosis cases.

CONCLUSION

The clue of the presence of NTM could be obtained on the first day of the hospital visit due to the point of care (POC) feature of smear testing and Xpert assay. About one-fourth of the NTM-isolated patients would benefit from this rapid, convenient, and reliable screening strategy in the given circumstance. Smear-positive/Xpert-negative outcome is an early, trustable indicator that is indicative of NTM isolation.

Doubled Nontuberculous Mycobacteria Isolation as a Consequence of Changes in the Diagnosis Algorithm

Background

Nontuberculous mycobacteria (NTM) and their associated diseases remain neglected. Through minor modifications in our diagnostic algorithm, we observed an unexpected higher number of cultivable NTM isolates. Therefore, a retrospective study was performed thoroughly to investigate the effect of changed laboratory procedures on NTM isolation in a specialized tuberculosis hospital.

Methods

NTM isolation rates and composition of NTM species were compared for the two diagnostic algorithms: (1) by using traditional p-nitrobenzoic acid (PNB) selective medium as a preliminary test to identify NTM isolates among the positive cultures (procedure I) and (2) by using the MPT64 antigen detection method to distinguish between Mycobacterium tuberculosis complex (MTBC) isolates and possible NTM isolates after a positive MGIT960 liquid culture (procedure II).

Results

The NTM isolation rate in procedure II was significantly higher than the procedure I (18.08% vs 9.71%; P<0.001). A noticeable increase in the ratio of NTM isolates among the identified mycobacteria was observed over the studied years (ie, from 58.18% in 2019 to 72.93% in 2021), which indicated a more precise prescription of species identification test after prompt information was provided in procedure II. In addition, the consistency of the identified species using multiple specimens from the same patient did not present a significant difference between the procedures.

Conclusion

According to our study, NTM infection might be far more underestimated than it is. A diagnostic procedure combining MGIT960 culture and MPT64 antigen detection could timely and easily identify clues of NTM isolates and improve the diagnosis of NTM infections.

Tuberculosis: a focused review for the emergency medicine clinician

INTRODUCTION

Tuberculosis (TB) is a common disease worldwide, affecting nearly one-third of the world's population. While TB has decreased in frequency in the United States, it remains an important infection to diagnose and treat.

OBJECTIVE

This narrative review discusses the evaluation and management of tuberculosis, with an emphasis on those factors most relevant for the emergency clinician.

DISCUSSION

TB is caused by Mycobacterium tuberculosis and is highly communicable through aerosolized particles. A minority of patients will develop symptomatic, primary disease. Most patients will overcome the initial infection or develop a latent infection, which can reactivate. Immunocompromised states increase the risk of primary and reactivation TB. Symptoms include fever, prolonged cough, weight loss, and hemoptysis. Initial diagnosis often includes a chest X-ray, followed by serial sputum cultures. If the patient has a normal immune system and a normal X-ray, active TB can be excluded. Newer tests, including nucleic acid amplification testing, can rapidly diagnose active TB with high sensitivity. Treatment for primary and reactivation TB differs from latent TB. Extrapulmonary forms can occur in a significant proportion of patients and involve a range of different organ systems. Patients with human immunodeficiency virus are high-risk and require specific considerations.

CONCLUSIONS

TB is a disease associated with significant morbidity and mortality. The emergency clinician must consider TB in the appropriate setting, based on history and examination. Accurate diagnosis and rapid therapy can improve patient outcomes and reduce the spread of this communicable disease.

Timing of treatment interruption among latently infected tuberculosis cases treated with a nine-month course of daily isoniazid: findings from a time to event analysis

Background

Treatment of latent tuberculosis infection (LTBI) in high-risk groups is an effective strategy for TB control and elimination in low incidence settings. A nine-month course of daily isoniazid (INH) has been the longest prescribed therapy; however, completion rates are suboptimal. We need data to guide TB program outreach efforts to optimize LTBI treatment completion rates.

Methods

We pooled seven (2009–2015) years of LTBI treatment outcome data. We computed the probability of INH treatment disruption over time by patient demographic and clinical risk factors. We used log-rank tests and Cox proportional hazards models to assess the risk factors for treatment disruption.

Results

We analyzed data from 12,495 persons with complete data on INH treatment initiation. Pediatric cases (0–17 years), recent contacts of active TB patients, and non-U.S.-born adults living in the United States ≤5 years represented 25.2, 13.0, and 59.2% of the study population, respectively. Overall, 48.4% failed to complete therapy. The median treatment duration was 306 days (95% CI: 297, 315). A significant drop in adherence could be observed around day 30 of treatment initiation. Indeed, by day 30 of treatment, 17.0% (95% CI: 16.4, 17.7) of patients had defaulted on therapy. Pediatric patients (HR = 0.83, 95% CI: 0.78, 0.89), recent contacts (HR = 0.74, 95% CI: 0.68, 0.81), patients with diabetes (HR = 0.77, 95% CI: 0.60, 0.98), and patients with HIV (HR = 0.39, 95% CI: 0.30, 0.51) had a lower risk of treatment default. However, black patients (HR = 1.57, 95% CI: 1.44, 1.70), Hispanic patients (HR = 1.54, 95% CI: 1.43, 1.66), and non-U.S.-born persons living in the United States ≤5 years (HR = 1.25, 95% CI: 1.18, 1.32) were significantly more likely to default on therapy.

Conclusions

In this analysis of INH treatment outcome, we see high levels of treatment discontinuation. On average, patients defaulted on their prescribed nine-month daily INH therapy within 30 days of initiating treatment, and those at increased risk of progression to active disease were most likely to do so. We highlight the need to introduce patient-centered programs to increase treatment adherence in this population.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7524-4) contains supplementary material, which is available to authorized users.

Design, Synthesis and Biological Evaluation of Some Triazole Schiff's Base Derivatives as Potential Antitubercular Agents

Background:

Tuberculosis (TB) is the second important cause of death worldwide caused by a bacterium called Mycobacterium tuberculosis. There is a need to find and develop new Anti-TB medications that are effective, inexpensive and suitable with human immunodeficiency virus and other anti-TB drugs used in many countries and mainly the developing countries where the disease is widespread. These drugs must be designed to shorten treatment time and to be active against resistant forms of the mycobacteria that will help to increase the patients compliance. A key compound which could be used as a lead to meet these requirements, is the thiolactomycin (TLM). This antibiotic which is naturally available has an ability to treat M. tuberculosis by inhibiting condensing enzymes called FAS II (mtFabH, KasA and KasB) which are related to biosynthesis of mycolic acid.

Methods:

Our main aims are to design and synthesize analogues of TLM as new lead molecules which could be a possible anti–TB candidate. To overcome the synthetic challenges associated with preparing the chiral TLM analogues; we synthesized and investigated a series of triazole analogues as inhibitors of KasA enzyme and the whole cell Mycobacteria. A series of twelve compounds were synthesized, purified and fully characterized using several spectroscopic techniques. Molecular modelling studies for our synthesised compounds were achieved by using a modelling program called AutoDock 4.2 utilising rigid docking.

Results:

Our results indicate that analogues of TLM show a good activity as compared to TLM.

Conclusion:

The activity obtained for the synthesized compounds against Mycobacteria tuberculosis indicate that the synthesised compounds 1, 2, 6 and 9 are pharmacologically active as they restrained the growth of the Mycobacteria bacteria.

A cost-benefit analysis of a proposed overseas refugee latent tuberculosis infection screening and treatment program

BACKGROUND

This study explored the effect of screening and treatment of refugees for latent tuberculosis infection (LTBI) before entrance to the United States as a strategy for reducing active tuberculosis (TB). The purpose of this study was to estimate the costs and benefits of LTBI screening and treatment in United States bound refugees prior to arrival.

METHODS

Costs were included for foreign and domestic LTBI screening and treatment and the domestic treatment of active TB. A decision tree with multiple Markov nodes was developed to determine the total costs and number of active TB cases that occurred in refugee populations that tested 55, 35, and 20 % tuberculin skin test positive under two models: no overseas LTBI screening and overseas LTBI screening and treatment. For this analysis, refugees that tested 55, 35, and 20 % tuberculin skin test positive were divided into high, moderate, and low LTBI prevalence categories to denote their prevalence of LTBI relative to other refugee populations.

RESULTS

For a hypothetical 1-year cohort of 100,000 refugees arriving in the United States from regions with high, moderate, and low LTBI prevalence, implementation of overseas screening would be expected to prevent 440, 220, and 57 active TB cases in the United States during the first 20 years after arrival. The cost savings associated with treatment of these averted cases would offset the cost of LTBI screening and treatment for refugees from countries with high (net cost-saving: $4.9 million) and moderate (net cost-saving: $1.6 million) LTBI prevalence. For low LTBI prevalence populations, LTBI screening and treatment exceed expected future TB treatment cost savings (net cost of $780,000).

CONCLUSIONS

Implementing LTBI screening and treatment for United States bound refugees from countries with high or moderate LTBI prevalence would potentially save millions of dollars and contribute to United States TB elimination goals. These estimates are conservative since secondary transmission from tuberculosis cases in the United States was not considered in the model.

Challenges of infectious diseases in the USA

In the USA, infectious diseases continue to exact a substantial toll on health and health-care resources. Endemic diseases such as chronic hepatitis, HIV, and other sexually transmitted infections affect millions of individuals and widen health disparities. Additional concerns include health-care-associated and foodborne infections--both of which have been targets of broad prevention efforts, with success in some areas, yet major challenges remain. Although substantial progress in reduction of the burden of vaccine-preventable diseases has been made, continued cases and outbreaks of these diseases persist, driven by various contributing factors. Worldwide, emerging and reemerging infections continue to challenge prevention and control strategies while the growing problem of antimicrobial resistance needs urgent action. An important priority for control of infectious disease is to ensure that scientific and technological advances in molecular diagnostics and bioinformatics are well integrated into public health. Broad and diverse partnerships across governments, health care, academia, and industry, and with the public, are essential to effectively reduce the burden of infectious diseases.

Application of Pulsed Field Gel Electrophoresis for Study of Genetic Diversity in Mycobacterium tuberculosis Strains Isolated From Tuberculosis Patients

Background:

Mycobacterium tuberculosis genotyping can effectively improve tuberculosis (TB) control programs by controlling disease transmission. Pulsed field gel electrophoresis (PFGE) is a particularly powerful tool for determination of clonal identity of bacteria providing information for understanding and controlling the spread of disease.

Objectives:

The aim of present study was to investigate the genetic diversity of M. tuberculosis strains in Khuzestan province by the PFGE technique.

Patients and Methods:

In total, 80 M. tuberculosis positive cultures were obtained from tuberculosis patients. PFGE was performed on 60 PCR-confirmed isolates by using DraI and XbaI restriction enzymes according to standard protocols. Plugs containing digested DNA were then loaded on agarose gels and run using contour-clamped homogenous electric fields.

Results:

Fifty distinct DNA banding patterns were obtained by digestion of DNA with DraI and 38 DNA banding patterns by digestion with XbaI restriction enzymes. The patterns comprised of 17 different clusters in which cluster I was the major one, containing six strains. Three clusters contained three strains each and the 13 remaining clusters comprised of two strains each. Digestion with DraI yielded 15-20 DNA fragments with 50-485 kb size, while digestion by XbaI produced DNA fragments with a size smaller than 50-242 kb.

Conclusions:

Despite the ability of PFGE for study of genetic diversity of many mycobacterial species and it being considered as a robust and useful tool, in this study we only found a 15% epidemiological relationship amongst the isolates. Thus, for higher discrimination of genotypic clusters among M. tuberculosis clinical isolates, the application of more sophisticated complementary techniques is required.

Alcohol and HIV: Experimental and Clinical Evidence of Combined Impact on the Lung

Despite antiretroviral therapy, lung disease is a leading cause of death in individuals infected with human immunodeficiency virus type 1 (HIV). Individuals infected with HIV are susceptible to serious bacterial and viral infections, such as pneumococcus and influenza, which are particularly problematic for lung health, resulting in lung injury. Additionally, HIV-infected individuals are susceptible to a number of pulmonary diseases for unknown reasons. Alcohol, the most commonly abused drug in the world, continues to exact an enormous toll on morbidity and mortality in individuals living with HIV. Chronic alcohol abuse has been shown to affect lung immunity, resulting in significant lung injury. There is a paucity of literature on the additive effects of HIV and alcohol, two diseases of immune senescence, in the lung. This chapter begins by discussing the latest literature evaluating the epidemiology of HIV, alcohol use, and lung health focusing on two prevalent infections, tuberculosis and pneumococcal pneumonia. In parallel, we discuss the interactions of alcohol and HIV on the risk for acute lung injury and subsequent morbidity and mortality. We then discuss the pathophysiology of how these two diseases of immune dysfunction affect the lung, with a focus on the oxidative stress, alveolar macrophage host immune capacity, and immunomodulatory role of zinc in the airway. Finally, we review the latest literature on how HIV and alcohol affect other pulmonary disorders including chronic obstructive pulmonary disease, pulmonary hypertension, and lung cancer.

D-cycloserine or similar physiochemical compounds may be uniquely suited for use in Bacillus anthracis spore decontamination strategies

AIMS

As observed in the aftermath of the anthrax attacks of 2001, decontamination and remediation of a site contaminated by the accidental or intentional release of Bacillus anthracis spores is difficult, costly and potentially damaging to the environment. The identification of novel strategies that neutralize the threat of spores while minimizing environmental damage remains a high priority. We investigated the efficacy of d-cycloserine (DCS), an antibiotic and inhibitor of the spore-associated enzyme (alanine racemase) responsible for converting l-alanine to d-alanine, as a spore germination enhancer and antimicrobial agent.

METHODS AND RESULTS

We characterized the impact of DCS exposure on both germinating spores and vegetative cells of fully virulent B. anthracis by evaluating spore germination kinetics, determining the minimum inhibitory concentrations (MICs) required to affect growth of the bacteria and performing macrophage viability assays. DCS enhanced germination induced by l-alanine and also efficiently killed the newly germinated spores. Furthermore, DCS proved nontoxic to macrophages at concentrations that provided protection from the killing effects of spores. Similar tests were conducted with Bacillus thuringiensis (subspecies kurstaki and Al Hakam) to determine its potential as a possible surrogate for B. anthracis field trials. Bacillus thuringiensis spores responded in a similar manner to B. anthracis spores when exposed to DCS.

CONCLUSIONS

These results further support that DCS augments the germination response of spores in the presence of l-alanine but also reveal that DCS is bactericidal towards germinating spores.

SIGNIFICANCE AND IMPACT OF THE STUDY

DCS (or similar compounds) may be uniquely suited for use as part of decontamination strategies by augmenting the induction of spore germination and then rendering the germinated spores nonviable.

Peritoneal tuberculosis in an immunocompetent, unknown risk patient

A 36-year-old man with no significant past medical history presented with two-month abdominal distention, night sweats, and weight loss of 15 Ib. He had no known exposure to tuberculosis. PPD test was negative prior to the hospital admission. Physical examination was notable for new onset ascites, but no superficial lymphadenopathy or stigmata of chronic liver disease was found. CT scan demonstrated enlarged mesenteric lymph nodes, and prominent retroperitoneal lymph nodes along with moderate ascites and omental infiltration. Diagnostic paracentesis yielded WBC of 295/mm³, lymphocytic predominance (70%), and serum ascitic albumin gradient of 0.1, consistent with exudate. Both the ascitic culture and AFB smear were negative, and ascitic cytology revealed nonmalignant cells. Exploratory laparoscopy for excisional biopsy of mesenteric lymph nodes was performed. Pathologic findings revealed caseous granulomas with scattered multinucleated giant cells. Mesenteric lymph node tissue culture subsequently grew Mycobacterium tuberculosis complex and the diagnosis of peritoneal tuberculosis was confirmed. The patient was started on quadruple therapy. A couple of days after the antibiotics were started, the small bowel obstruction started to resolve with resumption of bowel movements and tolerance of oral intake. A week later, ascites stopped accumulating and fever was no longer noted. He has been well and continues to be under observation.