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. 2016 Feb;8(1):62-9.

Emergence of colistin resistant Pseudomonas aeruginosa at Tabriz hospitals, Iran

Hamid Reza Goli  1 , Mohammad Reza Nahaei  1 , Mohammad Ahangarzadeh Rezaee  2 , Alka Hasani  2 , Hossein Samadi Kafil  1 , Mohammad Aghazadeh  1
Affiliations

Emergence of colistin resistant Pseudomonas aeruginosa at Tabriz hospitals, Iran

Hamid Reza Goli et al. Iran J Microbiol. 2016 Feb.

Abstract

Background and objectives: The prevalence of multidrug resistant Pseudomonas aeruginosa is the main reason of new drugs resurgence such as colistin. The main objectives of this study were to determine the antibiotic resistance pattern and the rate of colistin resistance along with its correlation with overexpression of MexAB-OprM and MexXY-OprM efflux pumps among P. aeruginosa isolates.

Materials and methods: Hundred clinical isolates were collected from 100 patients during 6 months in 2014. Susceptibility to the eight antibiotics was investigated using Kirby-Bauer and agar dilution methods. The Quantitative Real-time PCR was used to determine the expression levels of efflux genes.

Results: Resistance rates to various antibiotics were as follows: ticarcillin (73%), ciprofloxacin (65%), aztreonam (60%), ceftazidime (55%), gentamicin (55%), imipenem (49%), piperacillin/tazobactam (34%) and colistin (2%). In disk diffusion method, only two isolates were non susceptible to colistin, however in agar dilution method the two isolates were confirmed as resistant and two others were intermediate resistant. Sixty eight (68%) isolates were multi-drug resistant and 10 isolates were susceptible to all tested antibiotics. Both colistin resistant isolates showed overexpression of both efflux pumps, but two intermediate resistant isolates exhibited reduction of efflux genes expression.

Conclusions: Emergence of colistin resistance is increasing in P. aeruginosa indicating great challenge in the treatment of infections caused by MDR strains of this organism in Iran. ParRS may promote either induced or constitutive resistance to colistin through the activation of distinct mechanisms such as MDR efflux pumps, and LPS modification.

Keywords: Colistin; MexAB-OprM; MexXY-OprM; Multi drug resistant; Pseudomonas aeruginosa.

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Figures

Fig 1.
Fig 1.
Results of Antimicrobial Susceptibility testing and Number of MDR Isolates Abbreviations: TIC: Ticarcillin, PTZ: Piperacillin/Tazobactam, CAZ: Ceftazidime, AT: Aztreonam, IM: Imipenem, CO: Colistin, GM: Gentamicin and CIP: Ciprofloxacin.
Fig. 2.
Fig. 2.
Correlation between MIC ranges of colistin and overexpression of efflux pumps in P. aeruginosa
See this image and copyright information in PMC

References

    1. Dhariwal AK, Tullu MS. Colistin: re-emergence of the ‘forgotten’ antimicrobial agent. J Postgrad Med 2013; 59: 208– 15. - PubMed
    1. Martis N, Leroy S, Blanc V. Colistin in multi-drug resistant Pseudomonas aeruginosa blood-stream infections: a narrative review for the clinician. J Infect 2014; 69: 1– 12. - PubMed
    1. Hachem RY, Chemaly RF, Ahmar CA, Jiang Y, Boktour MR, Rjaili GA, et al. Colistin is effective in treatment of infections caused by multidrug-resistant Pseudomonas aeruginosa in cancer patients. Antimicrob Agents Chemother 2007; 51: 1905– 11. - PMC - PubMed
    1. Fernandez L, Gooderham WJ, Bains M, McPhee JB, Wiegand I, Hancock RE. Adaptive resistance to the “last hope” antibiotics polymyxin B and colistin in Pseudomonas aeruginosa is mediated by the novel two-component regulatory system ParR-ParS. Antimicrob Agents Chemother 2010; 54: 3372– 3382. - PMC - PubMed
    1. Lee JY, Na IY, Park YK, Ko KS. Genomic variations between colistin-susceptible and -resistant Pseudomonas aeruginosa clinical isolates and their effects on colistin resistance. J Antimicrob Chemother 2014; 69: 1248– 56. - PubMed

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