Proficiency testing of first- and second-line anti-tuberculosis drugs in Italy

Abstract

To the Editors: The emergence of drug-resistant tuberculosis (TB) is an increasing threat to public health in industrialised countries; thus, it is important to supervise mycobacteriology laboratories by performing periodic proficiency of anti-TB drug susceptibility testing (DST). In 1994, the World Health Organization (WHO) and the International Union against Tuberculosis and Lung Diseases developed a global project of anti-TB drug resistance surveillance to assist countries via a network of supranational reference laboratories (SRLs). Proficiency test (PT) results of first-line anti-TB drugs have been reported for the SRL network [1] and for some individual countries [2, 3]. The SRL in Rome, Italy, coordinated two PTs of first-line drugs in endemic countries in 2002–2006 [4] and two PTs of first-line drugs in Italy in 1998–2000 [5, 6]. The present study aims to verify whether the quality of DST in Italy changed after that time; to this end, a comprehensive survey of five PTs during a 13-yr period (1998–2010) is reported here, together with a pilot round of second-line drug PTs in 2010. Laboratories covering 18 out of 20 Italian regions participated in the PT exercise: 22 laboratories in 1998, 20 in 2000, 28 in 2003, 29 in 2007 and 30 in 2010. To maintain knowledge and skills, the laboratories were selected by the SRL on the basis of the number of patient samples analysed for DST. For instance, a mean of 88 first-line DSTs per laboratory (range 21–357) were performed in 2009. In 2010, 13 laboratories with a mean of 113 first-line and six second-line DSTs per laboratory in 2009 also performed the second-line drug PT. A mean of nine second-line DSTs per laboratory was performed in 2010. The Mycobacterium tuberculosis panels for first- and second-line drug PTs distributed by the Rome …