First Report of Colistin Resistance Gene mcr-1 in Carbapenem-Resistant Clinical Isolates of Klebsiella Pneumoniae in Iraq
Keywords:Carbapenem-Resistance K.pneumoniae, Colistin, mcr-1, MLST, CRKP.
Background: The prevalence of the plasmid-borne colistin resistance gene mcr-1 in bacteria poses a potential
threat to patient treatment, particularly when hospitalized spreading of this gene causes great concern as it
can transmit between different bacteria species. The aims of this study were to investigate the presence of
the mcr-1 gene among carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates from different clinical
specimens and determine the clonal origin of strains carrying the mcr-1 gene using Multi-locus sequence
typing (MLST) method.
Method: In this study, 22 CRKP isolates from clinical specimens collected from the major four hospitals in
Najaf/Iraq were examined. All isolates were identified by a standard biochemical test and confirmed by an
automated Vitek®2 system. Antimicrobial susceptibility test was done on 12 antibiotics by the disk diffusion
method. All isolates tested to detect the presence of the mcr-1 gene using the PCR method. Determine the
sequence typing by MLST for all mcr-1-positive CRKP isolates.
Results: Out of 147 K.pneumoniae, 22 carbapenem resistance isolates from different clinical specimens
were detected. Antibiotic sensitivity test results revealed that all isolates (100 %) were resistant to ampicillin,
Cefepime, Cefoxitin, Ceftazidime, and Ceftriaxone; however, most of the CRKP isolates (86.4 %) are
sensitive to colistin. The mcr-1 gene was found in three (13.6%) of the 22 isolates of CRKP.These three
isolates are resistant to all classes of antibiotics. The MLST results revealed that three mcr-1-positive CRKP
isolates were related to three different sequence types: ST147, ST1, and ST11.
Conclusion: The spread of CRKP isolates containing plasmid-borne mcr-1gene is worth our attention due
to the consider of colistin as the last resort treatment against drug-resistant pathogens that increasingly
identified in Najaf Hospitals/Iraq.