Cardiff Metropolitan University
849 - Peter Obee.pdf (2.88 MB)

Hospital surfaces and their importance in cross contamination and the spread and transmission of bacteria

Download (2.88 MB)
posted on 2022-10-14, 10:38 authored by Peter Obee


Healthcare associated infections (HCAI) place an economic burden on health services, and cause distress to patients and relatives. The recent rise in HCAI rates has been linked to poor standards of environmental hygiene, but clear evidence is lacking.

This thesis explores contamination on environmental and other surfaces, how it can be monitored, and its role in the spread of bacteria. Possible control measures and their incorporation into management strategy are also examined.

Investigations into different methods for sampling surfaces revealed that sampling efficiency could vary by 1000-fold. Such variation would hamper the management of decontamination intervention and highlights the need for standard methodologies.

The decontamination of medical instruments was assessed against an established standard, using methods developed in this study, and failure rates up to 45% were detected. Poor implementation, caused by poor process management and absence of routine monitoring, was a contributory factor.

Methods developed in this study were used to investigate the cleaning of ward surfaces. For some sites, benchmark cleaning values for bacteria were exceeded on 86% of occasions, and 100% of occasions for ATP. Simple modifications to cleaning practice produced significant improvements, but disinfectants did not offer advantages over detergents for routine cleaning.

Surface touches and their subsequent potential to contribute to the spread of bacteria was quantified using novel methodology, and it was found that the vicinity of the patients‟ beds was of key importance in the transfer of bacteria to patients.

Data gathered in preceding work was used to model exposure routes and determine the effect of implementing control measures. Effective hand decontamination reduced the mean transfer of bacteria to patients by 98.7%, but reductions in surface contamination also reduced the spread of bacteria. The benefits of hand decontamination could be undone with 2 touches of contaminated surfaces.

Overall, evidence was found to support the theory that hospital surfaces contribute to the spread of bacteria, and that surface cleaning may have some role in the control of HCAI.



  • School of Sport and Health Sciences

Qualification level

  • Doctoral

Qualification name

  • PhD

Publication year


Usage metrics

    Cardiff Met Theses Collection



    Ref. manager