Mycobacterium tuberculosis isolates belonging to katG gyrA group 2 are associated with clustered cases of tuberculosis in Italian patients

1 Dipartimento di Scienze Biomediche, Università degli Studi di Trieste, Via Fleming 22, 34127 Trieste, Italy 2 Modulo di Microbiologia Polmonare, Ospedale di Cattinara, Trieste, Italy Correspondence L. Dolzani Dolzani{at}dsbmail.units.it Received September 13, 2003 Accepted October 24, 2003 Fifty-one consecutive isolates of Mycobacterium tuberculosis , collected during a 2-year period in the north-east of Italy, were subjected to IS 6110 -RFLP analysis to detect the presence of clusters and assigned to one of the three genotypic groups delineated by single nucleotide polymorphisms in the genes katG and gyrA . All the isolates collected from the local population belonged to group 2 or 3, while group 1 isolates were found only in specimens collected from African immigrants. Clustered cases of tuberculosis, which are likely to be related to recently transmitted infection, were found to be significantly associated with katG gyrA group 2. In the local situation, strains belonging to this group may therefore present a higher risk of transmission.