Molecular Characterization of Extended Spectrum β-Lactamases, Ampccephalosporinases and Carbapenemases in Klebsiellapneumoniae Causing Bacteremia at Charles Nicolle Hospital of Tunisia
Purpose of the Study: This study was conducted to detect and characterize the genes encoding extended spectrum β-lactamases and associated β-lactamases (carbapenemases and Ambler Class C β-lactamases).
Patients and Methods: In 2011, out of the 65 non-duplicative Klebsiellapneumoniae collected from blood culture at Charles Nicolle hospital of Tunisia, 36 were resistant to 3rd generation cephalosporin.
Results: All strains showed a double disk synergy test positive. They were mainly isolated in intensive care unit (31%). They were frequently resistant to most antibiotics tested, except colistin and tigecyclin. Five isolates (13%) showed reduced susceptibility to carbapenems. blaCTX-M-15 was harbored by 35 strains and blaSHV-12 by one. blaCTX-M-15 were associated with blaTEM-1 (n=21), blaOXA-48 and blaCMY-2 (n=1) and blaOXA-48and blaTEM-1 (n=4). The conjugation wassuccessfulfor4/5 strains (3 harboring blaCTX-M-15 and one blaSHV-12). The plasmids carrying the blaCTX-M-15 were assigned to IncN or IncL/M only for 2 strains. The remaining blaCTX-M-15-carrying plasmid was negative for all of the replicons tested as well as the blaSHV-12-carrying plasmid.
Conclusion: Our results confirm the spread of CTX-M-15 in our institution. To our knowledge, this is the first report of K. pneumoniae coproducing CTX-M-15, CMY-2 and OXA-48. The implementation of preventive measures against the spread of these multiresistant bacteria is needed.