Prevalence of Colistin Resistance Among Clinical Isolates of Enterobacteriaceae Family in Palestinian Hospitals

Tasnim Ali AbdelMunem Abu Sibaa
تسنيم علي عبد المنعم أبو سباع
Journal Title
Journal ISSN
Volume Title
Al-Quds University
Background: Microbial resistance to antibiotic is an increasing global public health threats. Colistin are polycationic piptides antibiotics used as an effective traetment against multidrug resistant (MDR) gram negative bacteria mainly acting on lipopolysaccharide (LPS) and considred as one of the important antibiotics in human medicine despite its side effects and toxicity in some cases. Colistin resistance can be acquired by chromosomal mutations that affect the lipid A moiety of the lipopolysaccharide chain or by acquisition of MCR genes. Aims: The general aim of this study was to investigate the prevalence of colistin resistance among clinical Enterobacteriaceae isolates from Palestinian hospitals. In addition to identify Enterobacteriaceae spp that are resistant to colistin. A third aim, is to compare colistin susceptibility using the Disc Diffusion Method (DDM) in relation to the reference method; Broth Micro-Dilution Method (BMD). A fourth aim is to detect the plasmid coded gene (mcr-1) responsible for colistin resistance as a marker for colistin resistance. Methodology: A total of 80 bacterial isolates were collected from three hospitals in Palestine (AL-Makassed Hospital in Jerusalem, Al-Ahli Hospital and Alia Hospital in Hebron). The isolates were identified as Enterobacteriaceae and the speciation was done using Enterotube identification kit. The antimicrobial susceptibility testing for colistin was done by disc DD and BMD method. Furthermore, we used PCR reaction to detection of plasmid mcr-1 gene, which code for colistin resistance. Result: A total of 80 isolates were tested using DD and BMD method to determine the susceptibility of the clinical isolates to colistin. Only two isolates were colistin resistance one was Serratia marcescens and the other was Proteus mirabilis according to DDM results. However, when BMD method was used, ten (10) was identified; confirming the two isolates previously reported positive using DDM, the remaining were not detected by DDM. Escherichia coli was the most common organism among colistin resistance isolates (40%), followed by Proteus (20%), Serratia (20%), Enterobacter cloacae (10%) and Klebsiella pneumoniae (10%). Cifuroxime a beta lactum showed highest resistance (80%), followed by Ciprofloxacin a quinoone (55%). The most effective drug other than colistin, was Amikacin (80%) followed by v Gentamycin, Ertapenem, Merobenem and Tazobactum/Pipercillin (65%) respectively. All the colistin resistant isolates were tested negative for plasmid mcr-1 gene after amplification by PCR. Discussion: Colistin resistance is largely attributed to the PmrA-PmrB and PhoP-PhoQ regulatory systems and their responses to environmental changes. Resistance may also be Plasmid-mediated by the gene mcr-1. These limit and complicate treatment options of infection caused by Enterobacteriaceae in Palestinian Hospitals, which in turn calls for immediate actions to controlling and monitoring the use of antimicrobials in general and colistin in particular. Conclusion: High resistant rate was reported for colistin (12.5%) using BMD. Although, DDM was inexpensive and easy to perform, it failed to detect most of the colistin resistant isolates. BMD method was very reliable and gave excellent results although it is expensive and not routinely performed in the clinical microbiology laboratories. For plasmid detection using PCR, all the colistin resistant isolates tested negative for the mcr-1 gene, indicating that the cause of resistance could be physiologically or chromosomal mediated. Keywords: Drugs resistance, colistin antibiotic, plasmid mcr-1 gene, broth micro-dilution, Enterobacteriaceae family.