Volume 14, Number 5—May 2008
Perspective
Scale-up of Multidrug-Resistant Tuberculosis Laboratory Services, Peru
Sonya S. Shin*
, Martin Yagui†, Luis Ascencios†, Gloria Yale‡, Carmen Suarez‡, Neyda Quispe†, Cesar Bonilla‡, Joaquin Blaya§, Allison Taylor¶, Carmen Contreras#, and Peter Cegielski¶
, Martin Yagui†, Luis Ascencios†, Gloria Yale‡, Carmen Suarez‡, Neyda Quispe†, Cesar Bonilla‡, Joaquin Blaya§, Allison Taylor¶, Carmen Contreras#, and Peter Cegielski¶
Table 3
Optimal DST characteristics depending on MDR TB management strategy, Peru*
| Programmatic and epidemiologic features | Optimal DST characteristics |
|---|---|
| Standardized versus individualized regimens | |
| Standardized regimens for MDR based on regional resistance patterns | Centralized, complete DST (i.e., first- and second-line drugs) of representative samples to guide standardized treatment regimen; turnaround time less important |
| Individualized regimens |
Rapid, point-of-care DST optimal to accommodate high demand and minimize turnaround time. Semi-individualized regimens may be constructed if only DST to first-line drugs performed. |
| Who is tested for DST? | |
| Narrow DST indications (e.g., treatment failures only) | High pretest probability for MDR TB; therefore, optimal to perform DST to first- and second-line drugs to guide regimen design |
| Moderate DST indications (e.g., healthcare worker, smear-positive in second month of DOTS) | Rapid DST to first-line drugs to screen MDR TB versus non–MDR TB. If individualized treatment, drug-resistant samples may be referred for complete DST. Sensitivity may be more important than specificity because of greatest illness from failing to start appropriate treatment in patients with drug resistance. |
| Universal DST |
Rapid DST to first-line drugs to screen MDR TB versus non–MDR TB. Rapid point-of-care testing (decentralized) optimal. If individualized treatment, drug-resistant samples may be referred for complete DST. Sensitivity may be more important than specificity. |
| Epidemiologic features | |
| Patients with smear-negative disease (e.g., HIV, children) | Direct DST by using liquid medium or indirect DST after culture by liquid medium. Rapid turnaround time important given high illness rates in these risk groups. |
| High rates of resistance to second-line
drugs (XDR TB) |
Complete DST if high rates of resistance to second-line drugs, including XDR. If limited resources, DST to first-line drugs plus key second-line drugs (e.g., quinolone, kanamycin) to enable identification of XDR TB cases. |
| Management while awaiting DST results | |
| Empiric first-line regimen | Greater risk for inadequate treatment of MDR TB cases; rapid testing more important |
| Empiric MDR TB regimen | Less risk for inadequate treatment of MDR TB cases, excess cost and toxicity for non–MDR TB cases. Complete DST results permit adjustment of empiric MDR TB therapy. |
*DST, drug susceptibility testing; MDR TB, multidrug-resistant tuberculosis; XDR TB, extensively drug-resistant TB; DOTS, directly observed treatment, short course.
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Page updated: July 08, 2010
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