Standardization and implantation of the susceptibility test for second-line drugs for Mycobacterium tuberculosis: overview of extensively drug-resistant tuberculosis in São Paulo state

Abstract

The drug resistance in tuberculosis (TB) is a major threat to the public
health. In 2015, Worth Health Organization estimated that 9.5% of all
global multidrug-resistant TB (MDR-TB) cases were extensively drug
resistant TB (XDR-TB). This study was aimed the standardization of
susceptibility testing to the 2nd line drugs by BD BACTEC ™ MGIT
™ 960 method and to describe the overview of XDR-TB in São Paulo
state, in the years of 2006 and 20112013. Clinical, epidemiological and
demographic data were obtained from Notification and Monitoring System
of Cases of Tuberculosis and laboratory data was obtained from Adolfo
Lutz Institute’s Hospital Information and Management System. Statistical
analyses were performed using SPSS. The BD BACTEC ™ MGIT ™ 960
method was 100% reproducible and was validated through proficiency
testing. The prevalence of XDRTB cases among MDRTB cases in the
years 2006, 2011, 2012 and 2013 was respectively: 4.4%, 9.3%, 12% and
13.7%. The main drug resistance observed was ofloxacin. Regarding the
associated factors with resistance, the variables gender, previous history
of TB, notification type and outcome showed a statistically significant
difference between the groups. The molecular characterization of the
XDRTB cases, showed that 24 (63.1%) were grouped into 9 genotypes
by RFLP-IS6110 and epidemiological relationships were observed for 11
cases (28.9%). By Spoligotyping the families observed were: Haarlem,
T, LAM and X. The study allowed a better comprehension about XDRTB
in the state of São Paulo on the period studied.