Cooper, Ben (2000) The transmission dynamics of methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci in hospital wards. PhD thesis, University of Warwick.

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Abstract

This thesis presents a study of the transmission dynamics of nosocomial
pathogens in hospital wards, with particular reference to methicillinresistant
Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci
(VRE). The work makes use of mathematical models, and observational
and epidemiological studies.
Transmission dynamics of a potential pathogen are first explored using
a stochastic host-vector epidemic model, where health-care workers' hands
are assumed to be the vectors. Consequences of changes in patient management
are presented, and stochastic effects are shown to be essential to an
understanding of ward dynamics.

Observations of carer handwashing behaviour and carer-patient contact
patterns are described, and the factors associated with hand washing compliance
and contact rates explored using statistical models. Patient-carer
mixing patterns are investigated. Refinements to the host-vector model are
used to show how different aspects of observed contact patterns may both
increase and decrease the spread of nosocomial pathogens. For contact patterns
typical of intensive care units, the model predicts that infection rates
will increase as the staff-to-patient ratio decreases, so understaffing may
result in more cross-infection even if handwashing levels do not change.
The effect of antibiotic treatment on the spread of resistant strains is
studied using a two-strain model. Changing patterns of antibiotic use are
shown to be capable of causing large and rapid changes in ward prevalences
of resistant strains.
To investigate possible fitness costs, growth kinetics of methicillin-sensitive
and methicillin-resistant S. aureus strains are compared. No evidence for
differences in growth rates is found, though there is a suggestion that MRSA
stains may have longer lag periods.

Finally, a Markov chain Monte Carlo (MCMC) approach is developed to
enable model parameters to be estimated from the incomplete data typical
of ward-based epidemiological studies. The approach is used to estimate
parameters using S. aureus and VRE transmission data. With the latter
data, transmission rates were related to patient antibiotic use. All antibiotic
combinations considered were associated with increased acquisition rates,
the effect being strongest for cephalosporins.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	R Medicine > R Medicine (General) R Medicine > RA Public aspects of medicine > RA0421 Public health. Hygiene. Preventive Medicine
Library of Congress Subject Headings (LCSH):	Pathogenic microorganisms -- Research, Hospital wards -- Great Britain, Hospitals -- Medical staff -- Great Britain, Drug resistance in microorganisms , Methicillin resistance, Stochastic analysis
Official Date:	September 2000
Dates:	Date Event September 2000 Submitted
Institution:	University of Warwick
Theses Department:	Department of Biological Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Medley, Graham ; Scott, Geoffrey M.
Sponsors:	Wellcome Trust (London, England)
Extent:	xv, [283] leaves : illustrations
Language:	eng

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