BacteriologyFirst identification of methicillin-resistant Staphylococcus aureus MLST types ST5 and ST45 and SCCmec types IV and Vt by multiplex PCR during an outbreak in a respiratory care ward in central Taiwan☆,☆☆,★
Introduction
Methicillin-resistant Staphylococcus aureus (MRSA) is a worldwide problem with significant prevalence in Asia. In a study conducted in Taiwan, the prevalence of MRSA among isolates of S. aureus was reported to have increased from 39% in 1991 to 75% in 2003, with the increase attributed to the overuse of certain antibiotics (Hsueh et al., 2005).
Health care-associated MRSA (HA-MRSA) infection appears to be less common in respiratory care wards (RCWs) in Taiwan (Kuo et al., 2008). However, the Nosocomial Infection Control Subcommittee of our hospital became aware of an outbreak occurrence in the RCW in May 2006 because of the increasing number of patients infected with MRSA between March and May 2006, and subsequently intervened during the outbreak in June 2006. From March to June 2006, MRSA was isolated from eight patients and an outbreak of MRSA infection was suspected. The aim of this study was to use the results of a variety of molecular typing techniques to characterize the strains isolated from health care workers (HCWs) and patients during this outbreak. In so doing, we evaluated the feasibility of these molecular methods for application during an outbreak investigation performed by a standard clinical laboratory.
Section snippets
Outbreak scenario
The Chung-Kang branch of the Chung Shan Medical University Hospital is a 169-bed general hospital. The outbreak of MRSA infection occurred only on one floor in an RCW that cared for patients hospitalized with chronic respiratory failure and those requiring a ventilator. At the time of this investigation, the ward housed 23 inpatients, five of whom had renal failure and were undergoing regular hemodialysis. These patients were cared for by 67 HCWs (including three attending physicians and two
Incidence of carriage and infection by MRSA
The index patient (Patient 1) was admitted on January 4, 2005, and developed a urinary tract infection, pneumonia, and septic shock on March 13, 2006. MRSA was isolated from two sets of blood cultures. Between April 14 and June 17, 2006, eight episodes of MRSA infection were confirmed. Five patients had primary MRSA bacteremia, one of whom had two episodes of bacteremia during a period of 3 weeks (Patient 4). Ultimately, nine isolates obtained from eight patients were confirmed to be MRSA
Discussion
The goals of our study were to characterize a single MRSA outbreak in our institution with methods that could differentiate between cases that were associated with the index case and those that were not and to validate these methods in our routine clinical setting. For this purpose, we chose a combination of PFGE, multiplex PCR to determine the SCCmec and pvl gene type, and MLST typing. Our results from PFGE, MLST typing, multiplex PCR, and antibiograms derived from susceptibility testing of
Acknowledgment
We thank both the Center for Research and Diagnostics and the Central Regional Laboratory of Taiwan CDC for PFGE genetic typing analysis of MRSA strains.
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Cited by (21)
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2019, Journal of Microbiology, Immunology and InfectionCitation Excerpt :However, it remains uncertain whether the two strains, ST45 and ST188, identified from Vietnamese attendees in the present study had been common in Vietnam previously. In Taiwan, ST45 MRSA was relatively rare30 and was firstly identified during an outbreak investigation in 2006.31 Later in a study conducted in 2012, we found that 50% of the MRSA colonizing isolates were ST45 among the residents and staff, particularly foreign health care workers, from 14 nursing homes in Taiwan.32
Comparison of molecular epidemiology of bloodstream methicillin-resistant Staphylococcus aureus isolates between a new and an old hospital in central Taiwan
2019, International Journal of Infectious DiseasesCitation Excerpt :Some specific MRSA ST types found in this study deserve more discussion. MRSA ST45 strain was first identified in 2006 in Taiwan in a respiratory care ward, colonizing a proportion of infected patients and healthcare workers (Lee et al., 2011). Furthermore, it was found to be the predominant colonizing clone among residents and healthcare workers in 14 nursing homes in a survey conducted in 2012 (Tsao et al., 2015).
Predominance of methicillin-resistant Staphylococcus aureus in the residents and environments of long-term care facilities in Taiwan
2019, Journal of Microbiology, Immunology and InfectionCitation Excerpt :In 142 isolates with available MLST results, ST59 and ST45 were the predominant MLST types. ST-45 was first identified in Taiwan in 2011 in a respiratory care ward, gradually spreading to other facilities.30 ST-45 isolates became one of the predominant isolates in LTCFs in Taiwan as well as in many other countries, including Germany, Hong Kong, and China.14,31–33
Emergence of multidrug-resistant sequence type 45 strains among mecA-positive borderline oxacillin-resistant Staphylococcus aureus causing bacteraemia in a medical centre in Taiwan
2018, International Journal of Antimicrobial AgentsCitation Excerpt :Although an epidemic strain, ST45 MRSA has rarely been reported in Asian countries [6]. In recent surveillance, however, ST45 MRSA has been observed in healthcare facilities and colonising nursing home residents and their staff since its first identification in 2006 [9,10]. In addition to oxacillin, the antimicrobial susceptibilities of ST45 MRSA are less characterised compared with ST59 MRSA [10].
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Previous presentation: This study was presented as an abstract at the 11th Western Pacific Congress on Chemotherapy and Infectious Diseases, Dec. 1, 2008, Taipei, Taiwan.
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Funding and support: The study was supported by the Chung Shan Medical University Hospital Grant No. CSH-97-C-01.
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Conflict of interest: The authors declare that they have no conflict of interest.