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Volume 14, Number 5—May 2008
Perspective

Scale-up of Multidrug-Resistant Tuberculosis Laboratory Services, Peru

Sonya S. Shin*Comments to Author , Martin Yagui†, Luis Ascencios†, Gloria Yale‡, Carmen Suarez‡, Neyda Quispe†, Cesar Bonilla‡, Joaquin Blaya§, Allison Taylor¶, Carmen Contreras#, and Peter Cegielski¶
Author affiliations: *Brigham and Women’s Hospital, Boston, Massachusetts, USA; †Instituto Nacional de Salud, Lima, Peru; ‡Programa de Control de Tuberculosis, Lima, Peru; §Partners in Health, Boston, Massachusetts, USA; ¶Centers for Disease Control and Prevention, Atlanta, Georgia, USA; #Socios en Salud, Lima, Peru;

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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 created: July 08, 2010
Page updated: July 08, 2010
Page reviewed: July 08, 2010
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