Abstract
Background: The polymyxins including colistin are the “last resort” antibiotics for treatment of infections with carbapenem resistant Enterobacteriaceae. Recently, transferable colistin resistance mediated by the mcr-genes has been described in Enterobacteriaceae. The Testing of colistin susceptibility is challenging. The aim of the work is to detect the occurence of mcr-1 and mcr-2 genes in phenotypically colistin-resistant carbapenem resistant Escherichia coli and Klebsiella pneumoniae isolates using conventional PCR. Methods: One hundred and sixteen carbapenem-resistant E.coli and K.pneumoniae isolates were collected from patients admitted to different wards of Suez Canal University Hospitals in Ismailia. Urine, endotracheal aspirates, blood, pus and sputum specimens were collected from different patients. Minimal inhibitory concentration by broth microdiluton method was done to assess phenotypic colistin resistance. The colistin resistant E.coli and K.pneumoniae isolates were tested by conventional PCR to detect plasmid mediated mcr-1 and mcr-2 genes. Chi-square test was applied and p -value < 0.05 was considered statistically significant. Results: Forty three isolates out of 116 carbapenem resistant isolates (37.1%) were colistin resistant as shown by MIC by broth microdiluton method. The 43 colistin resistant E.coli and K.pneumoniae isolates were tested by conventional PCR to detect plasmid mediated mcr-1 and mcr-2 genes. Two mcr-2 genes and one mcr-1 gene were detected. Conclusion: Results revealed that the prevalence of colistin resistance among carbapenem-resistant E.coli and K.pneumoniae in SCUHs is concerning; further limiting potential therapeutic options. Plasmid mediated colistin resistance genes mcr-1 and mcr-2 is emerging in SCUHs which refer to a problem in the hospital as by horizontal transfer of this plasmid, the resistance can spread to many isolates in the hospital.
Highlights
The polymyxins including colistin are considered the last choice of antibiotics for treatment of infections with carbapenem resistant Enterobacteriaceae (CRE)
The mcr-1 gene firstly discovered in Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) in China [3], after that several studies across the world reported the presence of the mcr-1 gene in various bacteria from many other countries such as United States, European Union, Turkey, South Africa, Malaysia, Greece, Italy, Algeria, Tunisia and Kuwait [4]
The purpose of the present study is to evaluate the frequency of colistin resistance among E.coli and Klebsiella carbapenem resistant isolates obtained from patients in Suez Canal University Hospitals (SCUHs), and to determine how often mcr-1 and mcr-2 genes are detected among the colistin-resistant subset
Summary
The polymyxins including colistin are considered the last choice of antibiotics for treatment of infections with carbapenem resistant Enterobacteriaceae (CRE). Colistin resistance was considered only due to chromosomal mutations in the genes encoding the PmrA/PmrB and PhoP/PhoQ signalling systems or the negative regulator MgrB. These mutations cause modifications to the Lipid A molecule [2]. The aim of the work is to detect the occurence of mcr-1 and mcr-2 genes in phenotypically colistin-resistant carbapenem resistant Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) isolates using conventional polymerse chain reaction (PCR). The 43 colistin resistant E.coli and K.pneumoniae isolates were tested by conventional PCR to detect plasmid mediated mcr-1 and mcr-2 genes. Plasmid mediated colistin resistance genes mcr-1 and mcr-2 is emerging in SCUHs which refer to a problem in the hospital as by horizontal transfer of this plasmid, the resistance can spread to many isolates in the hospital
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