Resistance to first-line antituberculosis drugs in Spain, 2010-2011. RETUBES Study.

Introduction: The magnitude of current resistance to antituberculosis drugs in Spain is unknown. The objective of this study is to describe resistance to first-line antituberculosis drugs and determine the associated factors.

Methods: Prospective multicenter study of adult tuberculosis patients with positive Mycobacterium tuberculosis culture and antibiogram including first-line drugs in 32 hospitals and one out-patient center of the Spanish Health System between 2010 and 2011.

Results: A total of 519 patients, 342 Spanish nationals and 177 (34.1%) foreigners were studied. Drug resistance was found in 48 (9.2%), of which 35 (6.7%) were isoniazid-resistant. There were 10 (1.9%) multiresistant cases and no strain was extremely resistant. Initial isoniazid resistance was detected in 28 of the 487 (5.7%) antituberulosis-naïve patients, most of whom were foreigners (P<.01). Acquired resistance was seen in 7 (22.6%) previously treated cases. Multiresistance was initial in 6 cases (1.2%) and acquired in another 4 (12.9%). Factors associated with initial isoniazid resistance were immigrant status and group cohabitation OR=2.3; 95%CI: .98-5.67 and OR=2.2; 95%CI: 1.05-7.07 respectively). The factor associated with acquired resistance to isoniazid was age below 50 years (P=.03).

Conclusions: The rate of initial isoniazid resistance is greater than estimated, probably due to the increase in immigration during recent years, suggesting that systematic national monitoring is required. Immigrants and those who cohabit in groups have a higher risk of isoniazid resistance.