Objectives: Colistin has been increasingly used for the treating infections caused by carbapenem resistant bacteria. Resistance to colistin is increasingly being reported among carbapenem–resistant Enterobacteriaceae as well as Acinetobacter and Pseudomonas species. This study was undertaken to determine the frequency of colistin resistance among fermenter and non-fermenter Gram-negative rods in our setup.
Methods: The present study was conducted in the Microbiology section of Pathology Laboratory of Jinnah Burn and Reconstructive Surgery Centre, Lahore, Pakistan from April 2017 to August 2017. Gram-negative organisms, recovered from different specimens of hospitalized and follow-up burn patients resistant to all routinely used antimicrobial drug groups were included in the study. Colistin Minimum Inhibitory concentrations (MICs) were performed by E test for selected organisms.
Results: A total of 434 extremely-drug resistant Gram-negative bacteria, consisting of 244 Pseudomonas spp 126 Acinetobacter spp, 57 Klebsiella spp and 7 Escherichia spp were isolated during the present study. Among these Gram-negative bacteria, three Colistin resistant organisms were isolated. All three were non-fermenters. Two isolates were Pseudomonas aeruginosa and one was Acinetobacter baumnnii. The MIC results of Colistin as tested by E strip were 8 mg/ L for one Pseudomonas aeruginosa, 16 mg/L for the other Pseudomonas isolate and 12 mg/L for Acinetobacter species.
Conclusion: Our study highlights the emergence of Colistin resistance in non-fermenters. This is alarming, as it leaves almost no options for clinicians to treat infections caused by such organisms. It is the need of the hour to establish a policy for antimicrobial stewardship and to control antimicrobial resistance in our country.
Key words: Non-fermenters, Colistin, Carbapenem resistance.