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Investigating multidrug efflux pumps in relation to the antibiotic resistance pattern in Escherichia coli strains from patients in Iran

Objective: To investigate antibiotic resistance pattern of Escherichia coli strains isolated from patients admitted to the Shahid Mostafa Khomeini hospital in Behbahan city and survey its relationship with the presence of efflux pumps.

Methods: In this study, 180 isolates of E. coli were collected from Shahid Mostafa Khomeini hospital. After confirmation of strains by standard culturing methods and biochemical tests, their antibiotic resistance was evaluated with agar diffusion test and CLSI standards guidelines. The genes encoding the AcrA-AcrB-TolC efflux pump were identified with PCR.

Results: The percentages of resistance of the E. coli isolates to some antibiotics were as follow: novobiocin and rifampin, 68.9%; erythromycin, 52.8%; tetracycline, 52.2% and nalidixic acid, 51.7%. Isolates were sensitive to amikacin, 89.4%; tobramycin, 85.6%; meropenem, 81.7%; chloramphenicol, 77.8% and piperacillin, 65.6%, respectively. 110 (61.1%) strains from 180 taken isolates were found with multidrug- resistance (MDR) but no pandrug-resistance (PDR) was observed. 51.1%, 75.0% and 69.4% of isolates had genes acrA, acrB and tolC, respectively. Comparison of the results of antibiogram obtained from PCR with the two-way correlation test showed that there is a significant positive correlation between the presence of efflux pumps and resistance to antibiotics (excluding carbenicillin, meropenem, chloramphenicol, cefotaxime, rifampin and novobiocin).

Conclusion: Due to differences in antibiotic resistance in different strains is required using antibiotic resistance pattern for experimental and specific treatment of patients.

Author(s): Farshid Kafilzadeh, Farnoosh Farsimadan