Table 2 Laboratory methods to assess in vitro/ex vivo susceptibility of Plasmodium falciparum parasites to antimalarial drugs
From: Tools for surveillance of anti-malarial drug resistance: an assessment of the current landscape
| Â | WHO microtest | Isotopic | ELISA | Flow cytometry | SYBR green | RSA |
|---|---|---|---|---|---|---|
Infrastructure | Biosafety laboratory level 2 for parasite culture | Biosafety laboratory level 2 for parasite culture | Biosafety laboratory level 2 for parasite culture | Biosafety laboratory level 2 for parasite culture | Biosafety laboratory level 2 for parasite culture | Biosafety laboratory level 2 for parasite culture |
Equipment | Refrigerator Freezer Microscopy Biosafety cabinet Incubator with gas (CO2, O2 and N2) | Refrigerator Freezer Microscopy Biosafety cabinet Incubator (CO2 and O2) Liquid scintillation counter | Refrigerator Freezer Microscopy Biosafety cabinet Incubator with gas (CO2, O2 and N2) Spectrophotometer | Refrigerator Freezer Microscopy Biosafety cabinet Incubator with gas (CO2, O2 and N2) Flow cytometer | Refrigerator Freezer Microscopy Biosafety cabinet Incubator with gas (CO2, O2 and N2) Fluorimeter | Refrigerator Freezer Microscopy Biosafety cabinet Incubator with gas (CO2, O2 and N2) Flow cytometer) |
Reagents | Reagents for culture | Reagents for culture [3H] hypoxanthine | Reagents for culture HRP2/pLDH monoclonal antibodies Reagents for ELISA | Reagents for culture Fluorochrome | Reagents for culture SYBR Green | Reagents for culture Fluorochrome |
Incubation time (h) | 24–30 | 48 | 72 | 48 | 48 | 48 |
Time to results (12 samples) (h) | 38–42 | 52 | 80 | 54 | 52 | 60 |
Reproducibility | Variable | Good | Variable | Good | Good | Variable to good |
Cost by sample (USD $) | ≥ 5 | ≥ 5 | 1–5 (HRP2) 0.5–2 (pLDH) | ≥ 5 | 0.08 | ≥ 5 |
Advantages | No heavy equipment | Automatic reading | Relatively inexpensive | Highly sensitive | Inexpensive Short Procedure | No heavy equipment (except if using flow cytometry) |
Disadvantages | Labour intensive Requires quality assured microscopy Difficult to standardize Expensive | Use of radioactive reagents Heavy equipment Expensive | High inter-variability between laboratories and users No commercially available Kit for pLDH | Heavy equipment Expensive | Underestimation of parasitemia because of DNA-binding proteins competing with the dye Heavy equipment Interaction between drugs and the dye | Labour intensive (microscopy) Requires quality assured microscopy Difficult to standardize (microscopy) Heavy equipment (if using flow cytometry) Expensive |