Metallo-β-lactamase (MBL) producing bacteria constitute nowadays a serious global concern worldwide. The purpose of our present study was to characterize molecular features of MBL producing bacteria and to identify the existing clones in our area. Thirteen MBL-producing-Klebsiella pneumoniae were detected in clinical samples from patients hospitalized in the Military hospital of Tunisia during 2017. The molecular research by polymerase chain reaction and sequencing of gene encoding MBL enzymes showed that only two types were identified in our study: bla_NDM-1 and bla_VIM-1 genes detected, respectively, in eight and six isolates. An association between these two MBL genes (bla_NDM-1+bla_VIM-1) has been observed in one of our isolates. Other β-lactamase types (CTXM-15/4 isolates; SHV/2 isolates; OXA-48/3 isolates) were detected in association with New Delhi metallo-beta-lactamase (NDM) and/or Verona Integron-Mediated Metallo-β-lactamase (VIM) enzymes. Furthermore, these isolates were resistant to other antimicrobial agents, including gentamicin [aac(3)-II/11 isolates], tetracycline (tetB or tetA/2 isolates), chloramphenicol (cmlA and/or floR/3 isolates), streptomycin (aadA/5 isolates), and sulfonamides (sul1 or sul2 or sul3/4isolates). The Multilocus Sequence Typing revealed 10 different Sequence types (ST) of which 7 novel ST: ST147 (3 isolates), ST101 (1 isolate), ST630 (1 isolate), ST3485 (1 isolate), ST3486 (1 isolate), ST3487 (1 isolate), ST3488 (1 isolate), ST3489 (1 isolate), ST3490 (1 isolate), ST3491 (2 isolates). Our study provides new data about MBL producing K. pneumoniae in Tunisia. Thus, we report for the first time the coexpression of bla_NDM-1 and bla_VIM-1 in our country and also we describe seven novel ST of MBL producing K. pneumoniae in the world.

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