Outbreak of colistin-resistant carbapenemase-producing Klebsiella pneumoniae in Tunisia

Wejdène Mansour (1, 2) , Marisa Haenni (3) , Estelle Saras (3) , Raoudha Grami (1, 3) , Yosra Mani (1) , Anis Ben Haj Khalifa (4, 5) , Souhail El Atrouss (4) , Mohamed Kheder (4) , Mohamed Fekih Hassen (4) , Noureddine Boujâafar (1, 5) , Olfa Bouallegue (1, 6) , Jean-Yves Madec (3)

1 CHU Sahloul - Hôpital Universitaire Sahloul
2 Institut Supérieur des Sciences Appliquées et de Technologie de Mahdia
3 AVB - Unité Antibiorésistance et Virulence Bactériennes
4 Hôpital Tahar Sfar, Mahdia
5 UM - Université de Monastir - University of Monastir
6 Université de Sousse

Objectives: Mechanisms of colistin and carbapenem resistance among a collection of Klebsiella pneumoniae isolates recovered in a university hospital in Tunisia were studied. Methods: In vitro antimicrobial susceptibility testing, S1 nuclease pulsed-field gel electrophoresis (S1-PFGE), Southern blotting and PCR-based replicon typing (PBRT) were performed. Extended-spectrum b-lactamases (ESBLs), carbapenemases, AmpC-type enzymes and mgrB genes were detected by PCR and sequencing. Clonality of isolates was assessed by PFGE and multilocus sequence typing (MLST). Results: Of 940 Enterobacteriaceae isolates recovered from June 2015 to March 2016 in Tahar Sfar Hospital (Mahdia, Tunisia), 220 were identified as K. pneumoniae, among which 29 were carbapenem-resistant. Carbapenem resistance was mostly due to expression of bla OXA-48 or bla OXA-204 in combination with bla CMY-4. Seven isolates carried bla NDM-1 , of which two also harboured bla OXA-48 , together with bla CMY-16 in one of them. All but two isolates also harboured bla CTX-M-15. All 20 bla OXA-48 genes were part of transposon Tn1999 on an IncL plasmid, whereas bla OXA-204 was found on transposon Tn2016 on an IncA/C plasmid. Finally, all bla NDM-1 genes were located within a Tn125 transposon on an IncFIIk plasmid. Interestingly, 7 (24.1%) of 29 carbapenem-resistant isolates were resistant to colistin, of which 6 were assigned to ST101, had similar PFGE profiles and presented the same 2-kb insertion in the mgrB gene. Conclusions: This study reports, for the first time in Tunisia, the full molecular characterisation of colistin resistance in K. pneumoniae. There is an urgent need for control measures and prudent use of colistin in treatment of infections with carbapenemase-producing K. pneumoniae.

Mots clés: Klebsiella pneumoniae; OXA-48; NDM-1 inhibitors; MgrB

Domaines: Bactériologie

Wejdène Mansour, Marisa Haenni, Estelle Saras, Raoudha Grami, Yosra Mani, et al.. Outbreak of colistin-resistant carbapenemase-producing Klebsiella pneumoniae in Tunisia. Journal of Global Antimicrobial Resistance, 2017, 10, pp.88 - 94. ⟨10.1016/j.jgar.2017.03.017⟩. ⟨anses-04013258⟩