Differentiation among members of the Mycobacterium tuberculosis complex bymolecular and biochemical features: Evidence for two pyrazinamide-susceptible subtypes of M-bovis

The variations in biochemical as well as molecular characteristics among se veral members of the Mycobacterium tuberculosis complex that are not M. tub erculosis have been assessed to facilitate an unambiguous species identific ation. Altogether, 96 M. tuberculosis complex strains including 52 M. bovis isolates and 44 M. africanum isolates were analyzed by spoligotyping, The strains could be clustered into fire spoligotype groups. All ni. bovis isol ates showed the typical absence of the spacers 39 to 43 and typical biochem ical properties. However, within these strains we found a group of strains that had a spoligotype pattern which is clearly defined by the additional a bsence of spacers 3 to 16 and that were uncommonly susceptible to pyrazinam ide (PZA). This spoligotype pattern has previously been described as being typical for a caprine genotype because of its predominant isolation from sh eep and goats. Due to the clinical importance of PZA resistance, we propose two M. bovis subtypes: M. bovis subtype bovis, which is resistant to PZA, and M. bovis subtype caprae, which is susceptible to PZA Two additional str ains that clustered in group 3 showed biochemical and genetic properties ty pical for M. bovis and were also sensitive to PW; thus, they may represent a third PW-susceptible,li. bovis subtype. The,ll. africanum isolates could be clustered into two spoligotype groups which can be differentiated from M . bovis by hybridization to spacers 39 to 13. These groups correspond to th e previously described M. africanum subtypes I and II and can be clearly di stinguished from each other by spoligotyping and resistance to thiophen-2-c arboxylic acid hydrazide. Our results demonstrate that spoligotyping is a u seful tool for differentiation of M. bovis and M. africanum. Moreover, we d escribe two PZA-susceptible ni. bovis subtypes and describe a method that f acilitates an unambiguous differentiation of the two M. africanum subtypes.