The Effect of Triclosan Adaptation on Antimicrobial Resistance among Clinical Escherichia coli Isolates from Egyptian Patients

Eman A El-Masry,Ahmed E Taha,Soma E Ajlan

doi:10.22207/jpam.15.4.64

Abstract

There is a possible link between exposure to Triclosan (TCS) and changes in antimicrobial susceptibility. The change in the tolerance of clinical Escherichia coli (n=45) isolates to the biocide TCS, changes in antibiotic resistance and differences in the efflux pump mechanism were analyzed. 45 E. coli isolates were obtained. The minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC) of TCS, and the expression of four efflux pump encoding genes in antibiotic-resistant isolates were determined before and after TCS adaptation. The number of TCS-tolerant isolates was 11 (24.4%). After adaptation, the percentage of tolerant isolates increased to 42.2% (n=19). A significant change (p<0.05) in antimicrobial resistance of the tested isolates (n=45) before and after TCS adaptation was detected for ceftazidime, ceftriaxone, ertapenem, imipenem, amikacin, gentamicin, tobramycin, ciprofloxacin, levofloxacin and doxycycline. Among the new TCS tolerant isolates (n=8). there was an increase in TCS MIC as well as the MBC after TSC adaptation. The adapted isolates exhibited a significant increase in the expression of mdfA and norE genes (p=<0.001). There is a strong correlation between efflux pump gene overexpression and susceptibility to TCS and other antimicrobials.

Highlights

Triclosan (TCS) (2,4,4-trichloro-2-hydroxydiphenyl ether) is a broad spectrum non-antibiotic antimicrobial agent that is a common ingredient in more than 200 consumer products, such as detergents, soaps, disinfectants, toothpaste, and shower gels.[1]
TCS is characterized by a wide activity range against several microorganisms, for example, Staphylococcus aureus and Escherichia coli.[2,3]
Other studies investigated a decrease in antibiotic susceptibility in E. coli, Ps. aeruginosa, Salmonella, and S. aureus after exposure to biocide or adaptation.[36,37,38,39,40]. These findings indicated that exposure to biocides could alter antibiotic susceptibility

Summary

Introduction

Triclosan (TCS) (2,4,4-trichloro-2-hydroxydiphenyl ether) is a broad spectrum non-antibiotic antimicrobial agent that is a common ingredient in more than 200 consumer products, such as detergents, soaps, disinfectants, toothpaste, and shower gels.[1] TCS is characterized by a wide activity range against several microorganisms, for example, Staphylococcus aureus and Escherichia coli.[2,3]. TCS, like other biocides, is not used to treat host infections, and as a result, the regulations on use of this compound are not as strict as they are for antibiotics. Biocides are widely used without restrictions in many fields, such as the food industry, household hand-cleaning chemicals, and dental washing. Biocides may select for antibiotic-resistant microorganisms.[4] Even at low concentrations, TCS has been shown to cause antibiotic resistance via different mechanisms.[4,5]

Methods

Discussion

Conclusion