Pediatric tuberculosis-human immunodeficiency virus co-infection in the United Kingdom highlights the need for better therapy monitoring tools: a case report

Abstract

Background: Tuberculosis is an infection that requires at least 6 months of chemotherapy in order to clear the bacteria from the patient's lungs. Usually, therapeutic monitoring is dependent on smear microscopy where a decline in acid-fast bacilli is observed. However, this might not be indicative of the actual decline of bacterial load and thus other tools such as culture and molecular assays are required for patient management.

Case presentation: Here, we report the case of a 12-year-old Black African boy co-infected with tuberculosis and human immunodeficiency virus who remained smear culture positive and liquid culture negative for a prolonged period of time following chemotherapy. In order to determine whether there was any live bacteria present in his specimens, we applied the newly developed molecular bacterial load assay that detects the presence of 16S ribosomal ribonucleic acid derived from the bacteria. Using this methodology, we were able to quantify his bacterial load and inform the management of his treatment in order to reduce the disease burden. Following this intervention he went on to make a complete recovery.

Conclusions: This case report highlights the value of improved biomarkers for monitoring the treatment of tuberculosis and the role of molecular assays such as the molecular bacterial load assay applied here. The molecular bacterial load assay detects bacterial ribonucleic acid which corresponds closely with the number of live bacilli as compared with polymerase chain reaction that detects deoxyribonucleic acid and may include dead bacteria.

Keywords: Case report; Childhood tuberculosis; Clinical decisions; Molecular bacterial load; Rapid assay; Tuberculosis treatment monitoring.

Fig. 1

The clinical presentation of the patient over time. Three representative X-ray pictures from patient presentation, during therapy, and follow-up are shown on top of the graph. The time to positivity from culture is reported in days on the left y-axis with black squares. A time to positivity of 56 is considered to be negative. The molecular bacterial load values are shown on right y-axis as black dots. Smear microscopy is referred to as acid-fast bacilli positive or acid-fast bacilli negative for positive or negative samples respectively and is shown on the graph as diamonds. AAFB+ acid-fast bacilli positive, AAFB– acid-fast bacilli negative, CFU colony-forming unit, MBL molecular bacterial load, TTP time to positivity, ZN Ziehl–Neelsen