Investigating two component regulatory systems for the determination of adaptive responses in A. baumannii.

Evans, Laura Pauline (2013). Investigating two component regulatory systems for the determination of adaptive responses in A. baumannii. University of Birmingham. M.Phil.

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Abstract

To investigate the role of the two component systems AdeRS and PmrAB in adaptation to the presence of antimicrobials, adeRS and pmrAB were deleted in multi-drug resistant Acinetobacter baumannii strain AYE. The effect of deleting these genes on antimicrobial susceptibility, growth, accumulation, virulence and ability to form a biofilm was investigated. The deletion of adeRS and pmrAB had no effect on bacterial growth or the accumulation of Hoechst 33342 (bis-benzimide). AYE\(\Delta\)pmrAB, but not AYE\(\Delta\)adeRS, accumulated significantly more norfloxacin than AYE. All strains accumulated more norfloxacin in the presence of the efflux inhibitor carbonyl cyanide m-chlorophenylhydrazone. AYE\(\Delta\)adeRS and AYE\(\Delta\)pmrAB, but not AYE, accumulated more norfloxacin in the presence of verapamil. AYE\(\Delta\)adeRS was more susceptible than AYE to antibiotics and biocides and both strains in biofilm were more tolerant of biocides than their planktonic counterparts. Deletion of pmrAB had no effect on antibiotic susceptibility. AYE was more virulent than both AYE\(\Delta\)adeRS and AYE\(\Delta\)pmrAB. The results of this study suggest that in strain AYE, adeRS are not essential for efflux of norfloxacin or Hoechst 33342 and that pmrAB are involved in the accumulation of some compounds. Both AdeRS and PmrAB are important for virulence and AdeRS has a role in antimicrobial susceptibility.

Type of Work:

Thesis (Masters by Research > M.Phil.)

Award Type:

Masters by Research > M.Phil.

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