A report of the Australian Mycobacterium Reference Laboratory Network

The Australian Mycobacterium Reference Laboratory Network collected and analysed laboratory data on new cases of disease caused by Mycobacterium tuberculosis complex in the year 2002. A total of 712 cases were identifi ed by bacteriology, representing an annual reporting rate of 3.6 cases of laboratory-confi rmed tuberculosis per 100,000 population. The most commonly encountered culturepositive specimens were sputum (n=325), lymph node (n=142) and bronchoscopy (n=100). Smears containing acid fast bacilli were present in sputum (53.2%), bronchoscopy (37.9%) and lymph node (21.2%). Eight children (male n=3, female n=5) under 10 years of age had bacteriologically-confi rmed tuberculosis. A total of 55 isolates (7.7%) of M. tuberculosis were resistant to at least one of the standard anti-tuberculosis agents. Resistance to at least isoniazid and/or rifampicin was noted for 53 isolates (7.4%), with multidrug-resistance (MDRTB) observed in 12 (1.9%) isolates. Of the 12 MDRTB isolates, eight were from the respiratory tract and fi ve were from smear positive specimens. Of the patients with drug resistant M. tuberculosis isolates, 51/55 (92.7%) were classifi ed as having initial resistance, none had acquired resistance during treatment in Australia. The country of birth was known for 54 of 55 such patients; four were Australian-born, and 50 (90.9%) had migrated from a total of 17 countries. Nucleic acid amplifi cation testing (NAAT) was performed on 139 (19.5%) of the 712 culture-positive specimens. Of smear positive respiratory specimens, 74/80 (92.5%) were NAAT positive. For smear negative respiratory specimens, 12/17 (70.6%) reported a NAAT positive result. Importantly, falsenegative NAAT results were obtained from 1/16 and 5/64 of smear positive bronchoscopy and sputum specimens respectively. Commun Dis Intell 2003;27:459–465.