Distribution of spa types of methicillin-resistant Staphylocccus [sic] aureus in three local hospitals in Hong Kong

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Distribution of spa types of methicillin-resistant Staphylocccus [sic] aureus in three local hospitals in Hong Kong


Author: Au, Wing Yan
Title: Distribution of spa types of methicillin-resistant Staphylocccus [sic] aureus in three local hospitals in Hong Kong
Degree: M.Sc.
Year: 2013
Subject: Staphylococcus aureus -- Prevention.
Methicillin resistance.
Hospitals -- Sanitation.
Hong Kong Polytechnic University -- Dissertations
Department: Dept. of Health Technology and Informatics
Pages: xv, 149 leaves : ill. (chiefly col.), 1 col. map ; 30 cm.
Language: English
OneSearch: https://www.lib.polyu.edu.hk/bib/b2637217
URI: http://theses.lib.polyu.edu.hk/handle/200/7057
Abstract: Methicillin resistant Staphylococcus aureus (MRSA) is a clinically important pathogen. Not only is it entrenched in hospital settings, different clones of community-acquired MRSA (CA-MRSA) also emerge worldwide, causing a range of devastating infections including wound infections, toxic shock syndrome (TSS), bacteraemia, osteomyelitis, endocarditus, and the like. With a variety of drug resistant genes interchanging between strains, MRSA limits the therapeutic choice. The etiological agent is widespread in hospitals all over the world. Individuals with various risk factors are prone to MRSA infections. To tackle the problem, different infection control interventions have been set up in order to minimize spreading. Knowledge about the nature and number of MRSA clones that are disseminating is required because it helps to implement any strategies to control the transmission of the pathogen within the hospitals and in the community. Besides, studies of various risk factors associated with MRSA strains are needed. Nowadays, bacteraemia rate has been used as the indicator for assessing efficacy of infection control measures. In this project, spa typing which is a rapid and robust sequenced-based typing system to identify different MRSA strains based on the variable number of different repeats in the Staphylococcal protein A (spa) gene was used to identify spa type of 140 MRSA isolates recovered from blood cultures in 3 local hospitals, namely Caritas Medical Centre (CMC), Princess Margaret Hospital (PMH) and Yan Chai Hospital (YCH).
Four common endemic clones of MRSA of spa type t1081 (57.44%), t002 (10%), t032 (9.29%) and t037 (9.29%) were discovered in the 3 hospitals in descending prevalence. The dominance of spa type t1081 can be explained by the fact that this clone has better survival and higher transmissibility in hospital settings. Besides, these 3 hospitals have high admission rate of elderly patients from residential care home for the elderly (RCHE), where t1081 had been reported in high prevalence. The relationship of spa types with different parameters including wards with infections, specialties with infections and sources of infections were investigated and no special association could be identified. High prevalence of spa type t1081 in the wards, specialties and sources of infections was merely manifestation of spa type distribution in individual hospitals. The fact that the majority of bloodstream infections occurred in the medical and geriatric wards in the 3 hospitals in addition to the renal wards in PMH suggests heavy contamination of ward environment and transmission of MRSA carried along by a particular group of clinical staff associating with these wards. On the top of this, the spectrum of spa types were wider in these specialties, probably due to frequent admission, transfer and discharge of patients in these wards. Obviously, disinfection and infection control measures were not adequate in these wards. Besides, indwelling medical devices were found to be the most common source of infection, necessitating the need to enhance infection control measures targeting on this area. The discovery of 1 CA-MRSA and 2 community-onset hospital-acquired MRSA (HA-MRSA) demonstrated the transmission dynamics of MRSA between the hospitals and the community. To sum up, local bloodstream infections are dominated by the MRSA clone of spa type t1081. The infection control measures were not adequate in the 3 hospitals. Continuous monitoring of local molecular epidemiology is required in order to guide and improve the strategy for infection control interventions. Yet, collaborating effort is needed for both hospital staff and patients for high compliance to the infection control practice in order to minimize spreading of this notorious superbug.

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