Most TB cases are diagnosed through laboratory findings, with 70% of cases having a positive TB culture and 12% of cases having a positive PCR (without a positive culture).
Mycobacterium tuberculosis complex are a small group of closely related species of bacteria that cause tuberculosis disease in humans and animals. In NSW, M. tuberculosis is responsible for most TB disease (98%) with a small number of M. orygis (1%) and M. bovis (<1%) reported.
First line TB drugs consists of four antibiotics, isoniazid, rifampicin, ethambutol, and pyrazinamide. Most TB cases were fully susceptible to first-line drugs (91%). Drug resistance was uncommon overall, including resistance to isoniazid (5%), rifampicin (<1%), MDR-TB (1%) and pre‑XDR TB (<1%), with no XDR-TB identified.
Culture positive cases found to be linked to another NSW case by WGS are classified as being in a cluster. Linked cases are within 12 single nucleotide polymorphisms (SNPs) of another case in the same cluster.
34 (9%) Culture positive cases linked by WGS
27WGS clusters where new case was added
The first case in the cluster is the index case. Epidemiological investigations found a confirmed or possible link for 71% of cases in WGS clusters in 2025. A confirmed link is when there is direct contact between two cases, in both place and time, while the first case was infectious. A possible link is when there are similarities in place and time but a direct link is not identified when the first case was infectious.
The most common type of link, when known, to another case in the cluster was a community links (46%), followed by household, family and close friend links (38%). Community links can include sports, places of worship, other community groups or residence in the same geographical area.
