Tuberculosis in Australia: bacteriologically confirmed cases and drug resistance, 2008 and 2009. A report of the Australian Mycobacterium Reference Laboratory Network.

Abstract

There were 886 and 1,062 bacteriologically-confirmed cases of tuberculosis (TB) in 2008 and 2009, representing an annual rate of 4.1 and 4.9 cases per 100,000 population respectively. Over the 2 years, a total of 23 children aged under 10 years (male n = 13, female n = 10) had bacteriologically confirmed tuberculosis, including 3 children with TB meningitis. Results of in vitro drug susceptibility testing were available for 885 of 886 and 1,060 of 1,062 isolates for isoniazid (INH), rifampicin (RIF), ethambutol (EMB), and pyrazinamide (PYZ) in 2008 and 2009 respectively. In 2008, a total of 94 (10.7%) isolates of Mycobacterium tuberculosis complex were resistant to at least one of the anti-tuberculosis agents. Any resistance to INH was noted for 76 (8.7%), 23 (2.6%) for RIF, 10 (1.1%) for EMB and 9 (1.0%) for PYZ. Resistance to at least INH and RIF (defined as multidrug-resistant TB (MDR-TB) was detected in 21 (2.4%) isolates. None of the 21 MDR-TB isolates had resistance to either ofloxacin or the injectable agents. In 2009, a total of 168 (15.9%) were resistant to at least one of the anti-TB agents. Any resistance to INH was noted for 150 (14.2%) isolates, 37 (3.5%) for RIF, 5 (0.5%) for EMB and 13 (1.2%) for PYZ. A total of 31 (2.9%) isolates were MDR-TB. In 2009, there were 2 cases of quinolone resistance in MDR-TB from persons born overseas. Mono-resistance to INH was the most commonly detected resistance with 33 and 80 isolates in 2008 and 2009, respectively. Mono-resistance to RIF was infrequently encountered with 2 and 5 isolates in 2008 and 2009 respectively. There were six and 11 MDR-TB patients from the Papua New Guinea (PNG) - Torres Strait Islands (TSI) cross-border region in 2008 and 2009 respectively. The PNG-TSI zone now contributes a substantial proportion of MDR-TB cases to the database. In addition, there were 24 isolates of Mycobacterium bovis bacille Calmette Guérin (BCG), 15 were cultured from males (4 aged < or = 5 years) and from 9 females (5 aged < or = 5 years). The predominant site of isolation was from vaccination abscess. Eight males (range: 57-87 years) had M. bovis BCG isolated from urine or blood culture.