Enduring Challenge of Latent Tuberculosis in Older Nursing Home Residents: A Brief Review

The American Association of Tissue Banks tissue donor screening for Mycobacterium tuberculosis-Recommended criteria and literature review

After two multistate outbreaks of allograft tissue-transmitted tuberculosis (TB) due to viable bone, evidence-based donor screening criteria were developed to decrease the risk of transmission to recipients. Exclusionary criteria, commentary, and references supporting the criteria are provided, based on literature search and expert opinion. Both exposure and reactivation risk factors were considered, either for absolute exclusion or for exclusion in combination with multiple risk factors. A criteria subset was devised for tissues containing viable cells. Risk factors for consideration included exposure (e.g., geographic birth and residence, travel, homelessness, incarceration, healthcare, and workplace) and reactivation (e.g., kidney disease, liver disease, history of transplantation, immunosuppressive medications, and age). Additional donor considerations include the possibility of sepsis and chronic illness. Donor screening criteria represent minimal criteria for exclusion and do not completely exclude all possible donor TB risks. Additional measures to reduce transmission risk, such as donor and product testing, are discussed but not included in the recommendations. Careful donor evaluation is critical to tissue safety.

High all-cause mortality and increasing proportion of older adults with tuberculosis in Texas, 2008-2020

Pulmonary tuberculosis (PTB) elimination efforts must consider the global growth of the ageing population. Here we used TB surveillance data from Texas, United States (2008-2020; total n = 10656) to identify unique characteristics and outcomes in older adults (OA, ≥65 years) with PTB, compared to young adults (YA, 18-39 years) or middle-aged adults (40-64 years). We found that the proportion of OA with PTB increased from 15% in 2008 to 24% in 2020 (trend p < 0.05). Diabetes was highly prevalent in OA (32%) but not associated with adverse outcomes. Death was 13-fold higher in OA compared to YA and was 7% at the time of diagnosis which suggests diagnostic delays. However, once TB was suspected, we found no differences in culture, smear, or nucleic acid detection of mycobacteria (although less lung cavitations) in OA. During treatment, OA had less drug-resistant TB, few adverse reactions and adhered with TB treatment. We recommend training healthcare workers to 'think TB' in OA, for prompt treatment initiation to diminish deaths. Furthermore, OA should be added as a priority group to the latent TB treatment guidelines by the World Health Organization, to prevent TB disease in this highly vulnerable group.

Determining the Need for Additional Testing With Quantiferon TB Gold in Patients With Positive Tuberculin Skin Tests and a History of BCG Vaccination

OBJECTIVE

 To determine if the QuantiFERON-TB Gold (QFT) testing can be obviated for the diagnosis of latent tuberculosis infection (LTBI) in patients with a positive tuberculin skin test (TST) and a history of Bacillus Calmette-Guerin (BCG) vaccination by identifying high-risk features in patients with positive TST and a history of BCG vaccination who are associated with positive QFT.

METHODS

 Retrospective chart review was done for 76 adult patients by dividing them into two groups. Group 1 consisted of true positive TST patients who had BCG vaccination and were positive for QFT. Group 2 consisted of false positive TST patients who had BCG vaccination but were negative for QFT. The two groups were compared to determine if the high-risk features of TST induration diameter of 15mm and more, TST induration of 20mm and more, recent immigration to the US, the advanced age of more than 65 years, country of origin with high TB burden, known exposure to active TB, and smoking history were more prevalent in Group 1 compared to Group 2.

RESULTS

 Group 1 had 23 patients and Group 2 had 53 patients. Group 1 had a higher prevalence of patients with PPD induration of more than 10mm than Group 2, which was statistically significant with a P value of 0.03. Other risk factors of advanced age, exposure to active TB and smoking did not show statistically significant differences between Groups 1 and 2.  Conclusion: This study also confirms that if the TST induration is more than 10mm in patients with a history of BCG vaccination, the TST induration is likely because of LTBI and is less likely because of cross-reaction with BCG vaccination.

Determinants of latent tuberculosis infection and treatment interruption in long-term care facilities: A retrospective cohort study in Taiwan

BACKGROUND/PURPOSE

Latent tuberculosis infection (LTBI) treatment is challenging in long-term care facilities (LTCFs) residents due to the occurrence of medical complexities. However, factors associated with treatment interruption have not been extensively studied. This retrospective cohort study aimed to determine LTBI-associated factors and treatment interruption in LTCF residents and employees in Taiwan.

METHODS

From May 2017 through September 2020, the residents and employees of 20 LTCFs in Taipei, Taiwan, were screened for LTBI by using QuantiFERON-TB Gold In-Tube test. The LTBI individuals underwent directly observed preventive therapy (DOPT), including regimens of 9-month daily isoniazid (9H) and 3-month weekly isoniazid plus rifapentine (3HP). All the LTBI cases were followed up till treatment completion, death, or treatment interruption.

RESULTS

Among 2207 LTCF subjects, 16.8% had LTBI. After controlling for other covariates, residents of public facilities had a significantly higher LTBI prevalence than those of private facilities (adjusted odds ratio [AOR] = 1.43; 95% confidence interval [CI]: 1.08-1.88). Among 264 LTBI cases receiving preventive therapy, 52 (19.7%) had treatment interruption. LTBI cases receiving 3HP were less likely to have treatment interruption than those receiving 9H (AOR = 0.22; 95% CI: 0.07-0.71).

CONCLUSIONS

LTCF residents, particular those living in public facilities, had a high LTBI prevalence. 3HP with DOPT is considered the priority regimen for preventive therapy among LTBI cases in LTCFs.

Associating the blood vitamin A, C, D and E status with tuberculosis: a systematic review and meta-analysis of observational studies

Vitamins may play an important role in preventing tuberculosis. The purpose of this work is to associate the vitamin A, C, D and E status with tuberculosis through a systematic review and meta-analysis of observational studies. Web of Science, Pubmed and Scopus were searched from the earliest date of the database to May 2021. The standardized mean differences (SMDs) of blood vitamin concentrations and odds ratios (ORs) of vitamin deficiency between the tuberculosis patients and the control subjects were used as the main effect sizes. The effect sizes were pooled by a random-effects model using the Stata software (Version 11). The vitamin A concentration was significantly lower in the tuberculosis group than in the control group [SMD (95% CI): -0.96 (-1.31, -0.61), p < 0.01]. Only two case-control studies reported the vitamin C concentrations in the tuberculosis group versus the control group, and the difference was not significant. The blood vitamin D concentration was significantly lower in the tuberculosis group than in the control group [SMD (95% CI): -0.53 (-0.75, -0.32), p < 0.01]. Consistently, the number of people with vitamin D deficiency was significantly higher in the tuberculosis group [OR (95% CI): 2.29 (1.55, 3.37), p < 0.01]. The vitamin E concentration was significantly lower in the tuberculosis group than in the control group [SMD (95% CI): -0.34 (-0.61, -0.08), p = 0.01]. The current meta-analysis suggested a negative association between the vitamin A, D and E status and tuberculosis, and the association between the vitamin C status and tuberculosis was inconclusive due to the limited studies available.

Can immunization with Bacillus Calmette-Guérin be improved for prevention or therapy and elimination of chronic Mycobacterium tuberculosis infection?

Introduction: Tuberculosis (TB) is one of the most prevalent infectious diseases in the world. Current vaccination with BCG can prevent meningeal and disseminated TB in children. However, success against latent pulmonary TB infection (LTBI) or its reactivation is limited. Evidence suggests that there may be means to improve the efficacy of BCG raising the possibility of developing new vaccine candidates against LTBI.Areas covered: BCG improvements include the use of purified mycobacterial immunogenic proteins, either from an active or dormant state, as well as expressing those proteins from recombinant BCG strains that harvor those specific genes. It also includes boost protein mixtures with synthetic adjuvants or within liposomes, as a way to increase a protective immune response during chronic TB produced in laboratory animal models. References cited were chosen from PubMed searches.Expertopinion: Strategies aiming to improve or boost BCG have been receiving increased attention. With the advent of -omics, it has been possible to dissect several specific stages during mycobacterial infection. Recent experimental models of disease, diagnostic and immunological data obtained from individual M. tuberculosis antigens could introduce promising developments for more effective TB vaccines that may contribute to eliminating the hidden (latent) form of this infectious disease.