Genetic diversity of Mycobacterium tuberculosis in Madang, Papua New Guinea

SETTING: Madang and surroundings, Papua New Guinea (PNG). OBJECTIVE: To characterise the genetic diversity and drug susceptibility of Mycobacterium tuberculosis isolates collected in Madang and surroundings. DESIGN: M. tuberculosis was isolated from sputum samples from active pulmonary tuberculosis cases. Drug resistance profiles were obtained by drug susceptibility testing. M. tuberculosis lineages were identified by single nucleotide polymorphisms and sub-typing was performed by spoligotyping. Spoligotyping and 24 locus mycobacterial interspersed repetitive units-variable number of tandem repeats were combined to identify clustered isolates. RESULTS: The 173 M. tuberculosis isolates collected belonged predominantly to the Euro-American lineage (Lineage 4) and the East-Asian lineage (Lineage 2). Multidrug-resistant M. tuberculosis were observed in 5.2% of isolates. Lineage 2 M. tuberculosis, which includes the 'Beijing' genotype, was significantly associated with any drug resistance (OR 5.2, 95%CI 1.8-15.1). Cluster analyses showed 44% molecularly clustered isolates, suggesting transmission of M. tuberculosis in the community, including transmission of primary drugr esistant M. tuberculosis. CONCLUSION: These data provide the first insight into the molecular characteristics of M. tuberculosis in the Madang area of PNG, and indicate substantial drug resistance with evidence of ongoing transmission.