Diagnostic applications — Which of the following infections can be identified using polymerase chain reaction (PCR)-based assays?

Introduction / Context:
PCR and related nucleic acid amplification tests (NAATs) have transformed diagnostics by detecting pathogen-specific DNA or RNA with high sensitivity and specificity. The technology applies across viruses, bacteria, and parasites, enabling detection even when culture is slow or hazardous.

Given Data / Assumptions:

• PCR can target DNA directly or, via reverse transcription, RNA genomes.
• Clinical assays exist for multiple pathogens in blood, tissue, and respiratory samples.
• The listed pathogens include both viruses and bacteria of major clinical importance.

Concept / Approach:
HIV-1/HIV-2 (RNA retroviruses) are detected by RT-PCR to quantify viral load or confirm infection. Hepatitis B virus (DNA virus) is detected with PCR for diagnosis and monitoring. Mycobacterium tuberculosis (bacterium) is identified using PCR-based tests (e.g., MTB complex detection), which are faster than culture and can include resistance markers. Therefore, all listed infections are amenable to PCR-based detection.

Step-by-Step Solution:

Verification / Alternative check:
Clinical guidelines recommend NAATs for early HIV detection and viral load, HBV DNA monitoring, and rapid MTB diagnostics, validating PCR utility.

Why Other Options Are Wrong:

• Selecting a subset ignores established PCR assays for the others.

Common Pitfalls:
Assuming PCR is only for DNA viruses; RT-PCR extends detection to RNA viruses as routine practice.

Final Answer:
All of these