Regular Sputum Check-Up for Early Diagnosis of Tuberculosis after Exposure in Healthcare Facilities

Diagnostic value of miR-145 and its regulatory role in macrophage immune response in tuberculosis

Tuberculosis (TB) induced by Mycobacterium tuberculosis (Mtb) is a serious global health burden. This study sought to investigate the expression and diagnostic value of serum miR-145 in TB patients and explore the biological function of miR-145 using macrophages. Serum expression levels of miR-145 were estimated by quantitative real-time PCR. A receiver operating characteristic curve was plotted to evaluate the diagnostic accuracy of miR-145. This study further focused on the effects of miR-145 on cell viability and inflammation in macrophages upon Mtb infection, and explored the potential target gene of miR-145. Serum expression levels of miR-145 were decreased in TB patients, and the upregulated inflammatory cytokines in TB patients were negatively correlated with the serum expression levels of miR-145. miR-145 had considerable diagnostic accuracy in distinguishing of TB patients from healthy individuals and differentiating between active TB cases and latent TB cases. Mtb infection induced an increase in cell viability and inflammatory responses in macrophages, but these promoting effects were rescued by the overexpression of miR-145. CXCL16 was determined as a target gene of miR-145 in macrophages. Overall, this study demonstrated that the decreased serum miR-145 expression serves a candidate diagnostic biomarker in TB patients. The overexpression of miR-145 in macrophages upon Mtb infection can suppress cell viability and infection-induced inflammation via regulating CXCL16, indicating the potential of miR-145 as a therapeutic target of TB.

Disposal of the large volume of sputum positive for Mycobacterium tuberculosis by using microwave sterilisation technology as an alternative to traditional autoclaving in a tertiary respiratory care hospital in Delhi, India

Background

Everyday, tuberculosis hospitals collect enormous amount of sputum containing viable Mycobacterium tuberculosis bacilli, the disposal of which is a challenging task. Chemical (5% phenol) and physical (autoclaving) disinfection methods involve cost, space and cause further environmental degradation. Over the years, use of microwave for sterilisation of biomedical waste has become widespread. However, its efficacy to sterilise large volume of M. tuberculosis positive sputum has never been investigated.

Aim

To evaluate the effectiveness of microwave in sterilising large volumes of M. tuberculosis positive sputum samples.

Methods

226 sputum samples positive for M. tuberculosis were checked by Ziehl-Neelsen staining and liquid culture (MGIT ™) both before and after microwaving. χ² test was performed, and p-value <0.05 was considered significant.

Findings

Before microwaving, samples containing acid fast bacilli (AFB) and live M. tuberculosis bacilli were 93.8% and 95% (≈94.7%) respectively; which came down to 14.2% (32) and <1% (≈0.9%) in post microwave. In the 32 post-microwave AFB positive samples, bacilli appeared apoptotic, decreased in size, fragmented, loosely arranged and were easily missed as stain artefacts. Their beaded appearance was not appreciable. Background pus cells were of smaller size, did not take up methylene blue stain properly, and multilobed nuclear material was missing.

Conclusion

The study shows efficacy of microwave as an alternative sterilisation method for large volume sputum samples containing M. tuberculosis bacilli. Microwave can become an effective sterilisation method, especially for isolated tuberculosis care centres in countries which struggle for disposal of sputum, the biomedical waste.

A tuberculosis outbreak in a psychiatric hospital: Kanagawa, Japan, 2012

In January 2012, an inpatient in a ward of a psychiatric hospital with nearly 300 beds in Kanagawa, Japan, was diagnosed with sputum smear-positive pulmonary tuberculosis (TB). Here we characterise the TB outbreak cases and identify the population at risk. TB was diagnosed when a person tested bacteriologically positive for TB or was determined to have TB by a physician. A latent TB infection (LTBI) case was defined as a person tested positive by interferon-gamma release assay (IGRA). A total of 125 contacts were screened via IGRA and chest X-ray. In all, 15 TB and 15 LTBI cases were found by the end of October 2012, and thereafter no additional TB case was found. Of the 15 TB cases, eight were culture-positive and all the isolates had identical variable number tandem repeat patterns. Twenty-four of the 56 (42.9%, 95% confidence interval (CI) 29.7-56.8) inpatients in the ward had either TB or LTBI with a relative risk of 8.6 (95% CI 1.2-59.3), compared to the staff members who did not work full-time in the ward (one of 20 (5.0%, 95% CI 0.0-24.9)). We recommend that psychiatric hospitals conduct periodic screening of staff members and inpatients for TB to prevent nosocomial TB outbreaks.

Using genotyping to delineate tuberculosis transmission in long-term care facilities: single facility 4-year experience

Background

Residents in long-term care facilities (LTCFs) are vulnerable to tuberculosis (TB) transmission; however, to delineate possible routes of TB transmission in LTCFs is difficult. This study aimed to address the use of regular genotyping surveillance to delineate TB transmission in LTCFs.

Methods

All of Mycobacterium tuberculosis isolates in the reported 620-bed LTCF between July 2011 and August 2015 were genotyped, and we retrospectively compared epidemiological data and genotyping results.

Results

A total of 42 subjects were diagnosed with culture-positive pulmonary TB infection during the 4-year period. Their median age was 76.5 years, and 64.3% (27/42) of them were male. Genotyping identified 5 clustered TB infections involving 76.2% (32/42) of all TB subjects. In a multivariate logistic regression model adjusted for age, sex, chronic obstructive pulmonary disease, and body mass index, subjects with clustered TB infection were less likely to be Activities of Daily Living (ADL)-dependence (adjOR 0.073, 95% CI 0.007–0.758) when compared with subjects having individual TB infections. Prolonged surveillance is essential given that the median interval to diagnose secondary subjects was 673 days. Finally, only 63.0% (17/27) of the 27 secondary TB subjects in this study had contact history with index subject in the same ward.

Conclusions

In conclusion, possible routes of TB transmission in a complex TB outbreak at LTCFs might be delineated by routine genotyping surveillance and regular health check-up.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2526-2) contains supplementary material, which is available to authorized users.