First report of nosocomial infection caused by Klebsiella pneumoniae ST147 producing OXA-48 and VEB-8 β-lactamases in Tunisia

• First report of coproduction of OXA-48 and VEB-8 by clinical isolate of Klebsiella pneumoniae isolate belonged to ST147.
• KPM2 carried entB, ybtS, mrkD and ycfM virulence genes.
• KPM2 harboured blaOXA-48, blaVEB-8 in combination with the usual blaCMY-2, blaCTX-M-15 and blaTEM-1.
• The blaOXA-48 gene was embedded in transposon Tn1999.2 and was carried by a conjugative IncL/M plasmid of about 60 kb.
• blaVEB-8gene was harbored on a conjugative IncA/C plasmid of about 120 kb.

The aim of this study was to determine the origin of virulence and multiresistance of a Klebsiella pneumoniae isolate from an abdominal wound infection of a patient with a gunshot injury in the thoracoabdominal region. The isolate was identified using biochemical tests and Phoenix™ automated system and was confirmed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). MICs of each antibiotic were determined by Etest. Screening for carbapenemase production was performed by the modified Hodge test and was confirmed by PCR amplification. Virulence factors were also studied. Plasmid replicon typing was used to classify Incompatibility (Inc) plasmids harbouring the resistance genes. The transferability of each plasmid was determined by conjugation using Escherichia coli J53. Finally, multilocus sequence typing (MLST) was performed to determine the ST of the strain. The bacterial isolate was identified as K. pneumoniae and was named KPM2, carrying entB, ybtS, mrkD and ycfM virulence genes, but it did not overexpress OqxAB. Isolate KPM2 belonged to ST147 and was classified as resistant to all of the tested antibiotics with MICs above the clinical breakpoints. These resistances were due to production of OXA-48, CMY-2, TEM-1, CTX-M-15 and VEB-8 β-lactamases. Genetic and molecular studies showed that blaOXA-48 was embedded in transposon Tn1999.2 and was carried by a conjugative IncL/M plasmid of ca. 60 kb; blaVEB-8 was harboured on a conjugative IncA/C plasmid of ca. 120 kb. This study confirmed that the resistance conferred by OXA-48 and VEB-8 contributed to the failure of antibiotic treatment and consequently death of the patient.