Summary of recent diagnostic advances, their potential application and perceived problems and/or benefits
| Diagnostic approach | Application | Problems/Benefits | Validation | |||
|---|---|---|---|---|---|---|
| LAM, lipoarabinomannan; LTBI, latent tuberculosis infection; TST, tuberculin skin test. | ||||||
| Symptom-based | ||||||
| Symptom-based screening | Screening child contacts of adult tuberculosis cases | Simple, limited resources required | Not well validated | |||
| Should improve access to preventive chemotherapy for asymptomatic high-risk contacts The use of well-defined symptoms and clinical follow-up provides reasonable diagnostic accuracy | ||||||
| Refined symptom-based diagnosis | Diagnosis of probable active tuberculosis | Simple, limited resources required | Additional validation required | |||
| Should improve access to chemotherapy in resource-limited settings | ||||||
| Poor performance in HIV-infected children | ||||||
| Immune-based | ||||||
| Antibody-based assays | Diagnosis of probable active tuberculosis | Simple, point of care testing | Additional validation required | |||
| Variable accuracy and difficulty in distinguishing LTBI from active tuberculosis | ||||||
| Antigen-based assays | ||||||
| LAM detection assay | Diagnosis of probable active tuberculosis | Simple, point of care testing | Not well validated | |||
| Limited clinical data on accuracy | ||||||
| MPB64 skin patch test | Diagnosis of probable active tuberculosis | Simple and easy to use | Not well validated | |||
| Limited clinical data on accuracy, but initial data suggests it distinguishes LTBI from active tuberculosis | ||||||
| T cell assays | Diagnosis of LTBI; potentially a “rule-out” test for active disease | Limited data in children | Not well validated in children | |||
| Inability to differentiate LTBI from active tuberculosis | ||||||
| Large blood volumes required | ||||||
| Very expensive | ||||||
| Particular relevance in high-risk children, where LTBI treatment is warranted | ||||||
| Pathogen-based | ||||||
| Colorimetric culture systems (eg, TK-Medium) | Bacteriological confirmation of active tuberculosis | Simple and feasible, limited resources required | Not well validated in children | |||
| Potential for contamination in field conditions | ||||||
| Phage-based tests (eg, FASTPlaque-tuberculosis) | Diagnosis of active tuberculosis, and detection of rifampin resistance | Requires laboratory infrastructure | Not well validated in children | |||
| Performs relatively poorly when used on clinical specimens | ||||||
| Microscopic observation drug susceptibility assay | Diagnosis of active tuberculosis, and detection of drug resistance | Simple and feasible, limited resources required | Not well validated in children | |||
| Electronic-nose technology | Diagnosis of active tuberculosis | Still in development | Never tested in children | |||
| PCR-based tests | Diagnosis of probable active tuberculosis, and detection of rifampin resistance | Rarely available in endemic areas | Extensively evaluated, but evidence not in favour of widespread use | |||
| Sensitivity tends to be poor in paucibacillary tuberculosis | ||||||
| Specificity a concern in endemic areas, where LTBI is common | ||||||
| Requires adequate quality control systems | ||||||