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Front. Microbiol. | doi: 10.3389/fmicb.2018.02805

Colistin Induces S. aureus Susceptibility to Bacitracin

wei si1,  Liangliang Wang2, Valentine Usongo3 and  Xin Zhao3*
  • 1McGill University Health Centre, Canada
  • 2Tsinghua University, China
  • 3McGill University, Canada

Bacitracin has been used in topical preparations with polymyxin B for bacterial infections. Colistin belongs to the polymyxin group of antibiotics and is effective against most Gram-negative bacilli. This study investigated whether colistin could affect the susceptibility of S. aureus to bacitracin. S. aureus isolates were first incubated with colistin and the susceptibility of S. aureus to bacitracin was increased. The interaction between colistin and bacitracin on S. aureus was then confirmed by the checkerboard assay and the time-kill kinetics. The Triton X-100-induced autolysis was significant increased after S. aureus was exposed to colistin. Exposure to colistin also led to a less positive charge on the cell surface and a significant leakage of Na+, Mg2, K+, Ca2+, Mn2+, Cu2+ and Zn2+. Finally, disruptions on the cell surface and an irregular morphology were observed when the bacteria were exposed to colistin and bacitracin. Bacitracin had a stronger antibacterial activity against S. aureus in the presence of colistin. This could be due to the fact that colistin damaged the bacterial membrane. This study suggests that combination of colistin with bacitracin has a potential for treating clinical S. aureus infections.

Keywords: Bacitracin, Colistin, Staphylococcus aureus, antibiotic, susceptibility

Received: 14 Jun 2018; Accepted: 31 Oct 2018.

Edited by:

Santi M. Mandal, Indian Institute of Technology Kharagpur, India

Reviewed by:

Piyush Baindara, University of Arkansas for Medical Sciences, United States
Neelam Singh, Babasaheb Bhimrao Ambedkar University, India  

Copyright: © 2018 si, Wang, Usongo and Zhao. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Xin Zhao, McGill University, Montreal, H3A 0G4, Quebec, Canada, xin.zhao@mcgill.ca