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Title: Understanding the impact of biofilm on peracetic acid high-level disinfection and implication for infection transmission by complex semi-critical medical equipment
Author: Akinbobola, Ayorinde B.
ISNI:       0000 0004 7651 7022
Awarding Body: University of the West of Scotland
Current Institution: University of the West of Scotland
Date of Award: 2018
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High-level disinfectants can kill bacteria at concentrations much lower than the concentrations used clinically for the disinfection of semi-critical medical equipment like endoscopes. Despite this, bacterial cell survival of high-level disinfection of endoscopes have been widely reported with biofilm formation in the channels of endoscopes identified as the cause of some reported cases of endoscope reprocessing failures. The impact of biofilm formation on high-level disinfection using peracetic acid (PAA), a commonly used oxidising agent for high-level disinfection was investigated in this research. This research also elucidated the mechanism of biofilm tolerance to PAA. To appreciate the impact of biofilm formation on PAA high-level disinfection, the susceptibility of planktonic cells to PAA and the impact of conditions which can occur during endoscope reprocessing on the susceptibility of planktonic cells to PAA were initially evaluated. Results from the planktonic studies demonstrated that the efficacy of PAA high-level disinfection can be compromised by a combination of the conditions investigated. Evaluation of biofilm impact on bacteria cell susceptibility to PAA showed that biofilm formation mediated a 100-fold increase in the minimum concentration of PAA required to kill Pseudomonas aeruginosa cell used for this research with aged biofilm (96 and 192 hours old) surviving at concentration of PAA used clinically for high-level disinfection. Thus, indicating that biofilm if allowed to build-up in endoscopes can cause high-level disinfection failures. Further studies to identify the mechanisms of biofilm tolerance to PAA showed that biofilm tolerance to PAA is influenced not only by the volume of biofilm extracellular matrix (ECM) but also by the relative abundance of the components of the biofilm ECM. The formation of biofilm mediated population variant with unique cultural and physiological attributes in the biofilm of the P. aeruginosa was also identified as a mechanism of tolerance to PAA. Investigation of the effect of PAA on the ECM of biofilm showed that PAA has poor effect on biomass of disinfected biofilm and biofilms formed if biomass of biofilms killed with PAA were recolonised have enhanced tolerance to PAA. The role of carbapenem resistant mechanisms in the recent prevalence of endoscope mediated carbapenem resistance Enterobacteriaceae (CRE) infection transmission was investigated. Result from the study showed that biofilms of carbapenem resistant isolates used were more tolerant to PAA compared to biofilm of carbapenem susceptible isolate
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available