First Report of SHV-148-Type ESBL and CMY-42-Type AmpC β-Lactamase in Klebsiella pneumoniae Clinical Isolates in Tunisia

Abstract

Extended-spectrum beta-lactamase producing Enterobacteriaceae present a real problem worldwide. We aimed to investigate the molecular mechanisms of resistance to antibiotics among Klebsiella pneumoniae clinical isolates collected from a Hospital in the southeast of Tunisia. Eighteen cephalosporin–resistant K. pneumoniae were recovered between April 2015 and August 2016. Molecular characterization of antimicrobial resistance encoding genes was performed by PCR and sequencing. Results revealed several types of Ambler class A β-lactamase encoding genes among our isolates: [bla_CTXM-15 (15), bla_SHV-28 (6), bla_SHV-1 (2), bla_SHV-148 (1), bla_SHV-61 (1), bla_SHV-76 (1), bla_SHV-186 (1), bla_TEM-1 (8)]. The association of bla_OXA-1 was observed in nine isolates. However, the class C β-lactamase encoding genes were detected in four isolates [bla_CMY-4 (2), bla_CMY-42 (1), bla_ACT-35 (1)]. Molecular typing of K. pneumoniae isolates by pulsed-field gel electrophoresis showed 16 unrelated pulsotypes proving a high diversity among our isolates. Our study provides new epidemiological information showing a huge diversity of β-lactamase encoding genes among our isolates. In fact, this is the first report of SHV-76, SHV-148, and SHV-186 in Tunisia. This is also the first report of CMY-42 and ACT-35 producing K. pneumoniae in our country.