SMaRT-PCR: sampling using masks and RT-PCR, a non-invasive diagnostic tool for paediatric pulmonary TB

BACKGROUND

Key challenges in paediatric TB diagnosis are invasive sampling and poor sensitivity of standard methods. This study demonstrates the diagnostic potential of non-invasive sampling of bioaerosols from children using SMaRT-PCR, comprising mask sampling combined with reverse transcriptase-polymerase chain reaction (RT-PCR) for TB.

METHODS

Exhaled bioaerosols were captured on modified N-95 masks in a 10-min talk-cough-breathe process from 51 children (30 with TB confirmed using standard sampling methods and 21 without TB) aged 2-15 years. All mask samples were tested using in-house RT-PCR for 16s and rpoB RNA transcripts. Additional mask samples from children with TB were tested using Xpert® MTB/RIF (n = 3) and Xpert® MTB/RIF Ultra (n = 27).

RESULTS

SMaRT-PCR sensitivity for detecting TB among treatment-naïve children was 96% if 16s or rpoB was present, and 75% if both genes were present, comparable to standard methods (71%) in the same cohort. Specificity was better for both genes, at 95%, than 85% for a single gene detection. Mask sampling with Xpert MTB/RIF or Ultra had a sensitivity of only 13%.

CONCLUSION

This is the first study to provide evidence for testing bioaerosols as a promising alternative for detecting paediatric TB. Sampling is non-invasive and simple, with the potential for point-of-care applications. This pilot study also suggests that RNA transcript-based detection may improve TB diagnostic sensitivity in children; however, further investigation is required to establish its adaptability in clinical settings..

Prevalence and causes of undernutrition in medical outpatients

PURPOSE

To assess the prevalence, common causes, and frequency of recognition and treatment of undernutrition in older and younger medical outpatients using a cross-sectional survey design with 2-year follow-up of undernourished subjects.

PATIENTS AND METHODS

Charts of 1017 adult patients attending a hospital outpatient department were reviewed for the presence of undernutrition, and 85 patients meeting inclusion criteria for undernutrition were evaluated and followed for 2 years. An initial evaluation focused on nutritional, cognitive, and affective status and on nutritional attitudes using two subscales of the EAT-26 eating disorder inventory. After 2 years, initial data plus outpatient records were evaluated by 2 independent reviewers to determine a primary cause of undernutrition and to assess the recognition and treatment of undernutrition by the primary physician.

RESULTS

Undernutrition was identified in 46 (11%) and 44 (7%) of older and younger subjects respectively; odds ratio (OR) (95% [confidence interval (CI)]) for older versus younger=1.65 (1.06 to 2.51). The primary cause of undernutrition differed between age groups but was deemed treatable in nearly 90% of all subjects. Undernutrition was recognized in 19 (43%) older subjects and 5 (12%) younger subjects (OR=5.47 [1.87 to 16.0]), and appropriate intervention(s) were instituted in 6 (14%) and 2 (5%) of older and younger subjects, respectively (OR=3.08 [0.668 to 14.21]). Older subjects scored higher on the EAT-26 oral control subscale than did younger subjects (4.7 versus 2.5, P=0.004) but similarly on the EAT-26 dieting subscale (5.2 versus 6.3, P=0.332); these relationships did not change with control for potentially confounding variables.

CONCLUSIONS

In this study, undernutrition was relatively common, usually amenable to treatment, but frequently undetected and undertreated in both older and younger medical outpatients. Older undernourished subjects exhibited higher oral control needs than younger persons, which may have implications for the pathophysiology and treatment of their malnutrition. Further improvement in detection and intervention is warranted in both younger and older age groups.