Ldt_Mav2, a nonclassical transpeptidase and susceptibility of Mycobacterium avium to carbapenems

Aim: Mycobacterium avium infections, especially in immune-compromised individuals, present a significant challenge as therapeutic options are limited. In this study, we investigated if M. avium genome encodes nonclassical transpeptidases and if newer carbapenems are effective against this mycobacteria. Materials & methods: Biochemical and microbiological approaches were used to identify and characterize a nonclassical transpeptidase, namely L,D-transpeptidase, in M. avium. Results & conclusion: We describe the biochemical and physiological attributes of a L,D-transpeptidase in M. avium, Ldt_Mav2. Suggestive of a constitutive requirement, levels of Ldt_Mav2, a L,D-transpeptidase in M. avium, remain constant during exponential and stationary phases of growth. Among β-lactam antibacterials, only a subset of carbapenems inhibit Ldt_Mav2 and tebipenem, a new oral carbapenem, inhibits growth of M. avium.