Co-occurrence of genes encoding carbapenemase, ESBL, pAmpC and non-β-Lactam resistance among Klebsiella pneumonia and E. coli clinical isolates in Tunisia.

This study aimed to investigate the molecular mechanisms of carbapenem and colistin resistance in K. pneumoniae and E. coli isolates obtained from hospitalized patients in Carthagene International Hospital of Tunis. A total of 25 K. pneumoniae and 2 E. coli clinical isolates with reduced susceptibility to carbapenems were recovered. Susceptibility testing and phenotypic screening tests were carried out. ESBL, AmpC, carbapenemase and other antibiotic resistance genes were sought by PCR-sequencing. The presence of plasmid-mediated colistin resistance genes (mcr-1-8) was examined by PCR and the nucleotide sequence of the mgrB gene was determined. The analysis of plasmid content was performed by PCR-Based Replicon Typing (PBRT). The clonality of isolates was assessed by PFGE and multilocus sequence typing (MLST). All of the isolates produced carbapenemase activity. They showed a great variation in the distribution of ESBL, AmpC, carbapenemase and other plasmid-mediated resistance determinants. K. pneumoniae isolates carried blaNDM-1 (n = 11), blaOXA-48 (n = 11), blaNDM-1 + blaOXA-48 (n = 1), blaNDM-1 + blaVIM-1 (n = 1), blaOXA-204 (n = 1), along with blaCTX-M , blaOXA , blaTEM , blaCMY , blaDHA and blaSHV genes variants on conjugative plasmid of IncL/M, IncR, IncFIIK , IncFIB, and IncHI1 types. Three sequence types ST101, ST307 and ST15 were identified. The mgrB alteration g109a (G37S) was detected in a single colistin-resistant, NDM-1 and OXA-48-coproducing K. pneumoniae isolate. The two E. coli isolates belonged to ST95, co-produced NDM-1 and CTX-M-15, and harboured plasmid of IncFII and IncFIB types. To our knowledge, this is the first report in Tunisia of NDM-1, OXA-48, and CTX-M-15 coexistence in colistin-resistant K. pneumoniae ST15.

Ben Sallem R ，Laribi B ，Arfaoui A ，Ben Khelifa Melki S ，Ouzari HI ，Ben Slama K ，Naas T ，Klibi N ... -  《-》

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

Mechanisms of colistin and carbapenem resistance among a collection of Klebsiella pneumoniae isolates recovered in a university hospital in Tunisia were studied. 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 β-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). 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 blaOXA-48 or blaOXA-204 in combination with blaCMY-4. Seven isolates carried blaNDM-1, of which two also harboured blaOXA-48, together with blaCMY-16 in one of them. All but two isolates also harboured blaCTX-M-15. All 20 blaOXA-48 genes were part of transposon Tn1999 on an IncL plasmid, whereas blaOXA-204 was found on transposon Tn2016 on an IncA/C plasmid. Finally, all blaNDM-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. 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.

Mansour W ，Haenni M ，Saras E ，Grami R ，Mani Y ，Ben Haj Khalifa A ，El Atrouss S ，Kheder M ，Fekih Hassen M ，Boujâafar N ，Bouallegue O ，Madec JY ... -  《-》

Molecular characteristics of antibiotic-resistant Escherichia coli and Klebsiella pneumoniae strains isolated from hospitalized patients in Tehran, Iran.

Sharahi JY ，Hashemi A ，Ardebili A ，Davoudabadi S ... -  《Annals of Clinical Microbiology and Antimicrobials》

Characterization of Resistance Genes and Polymerase Chain Reaction-Based Replicon Typing in Carbapenem-Resistant Klebsiella pneumoniae.

Erdem F ，Oncul O ，Aktas Z 《-》

Multidrug-resistant Klebsiella pneumoniae harboring extended spectrum β-lactamase encoding genes isolated from human septicemias.

Carvalho I ，Chenouf NS ，Carvalho JA ，Castro AP ，Silva V ，Capita R ，Alonso-Calleja C ，Enes Dapkevicius MLN ，Igrejas G ，Torres C ，Poeta P ... -  《PLoS One》