Evolution of Sporadic Isolates of Methicillin-Resistant Staphylococcus aureus (MRSA) in Hospitals and Their Similarities to Isolates of Community-Acquired MRSA

Abstract

Forty-one methicillin-resistant Staphylococcus aureus (MRSA) hospital isolates that clearly differed from the six major pandemic clones of MRSA in pulsed-field gel electrophoresis type, mecA and Tn554 polymorphism, and epidemic behavior were selected from an international strain collection for more detailed characterization. SpaA typing, multilocus sequence typing, and SCCmec (staphylococcal cassette chromosome mec) typing demonstrated extensive diversity among these sporadic isolates both in genetic background and also in the structure of the associated SCCmec elements. Nevertheless, the isolates could be grouped into restricted clonal complexes by using the BURST (i.e., based upon related sequence types) program algorithm, which predicted that most sporadic MRSA isolates evolved from pandemic MRSA clones. Several of the sporadic MRSA resembled community-acquired MRSA isolates in properties that included a relatively limited multiresistance pattern, faster growth rates, diversity of genetic backgrounds, and a frequent association with SCCmec type IV.

Multilocus Sequence Typing of Methicillin-Resistant Staphylococcus aureus from an Area of Low Endemicity by Real-Time PCR

“…The presence of more than one different type of SCCmec in the same ST indicates, in congruence with other studies (1,7), that the MRSA clones arose at several occasions in the same genetic background by independent acquisition of SCCmec into methicillin-sensitive strains. This circumstance denotes the importance of combining MLST data with the SCCmec typing results when trying to understand the origins of MRSA.…”

“…MLST of large numbers of MRSA from different geographic areas has revealed that there are five major clonal lineages that are internationally dominating (1,4,24). However, community-acquired MRSA are found to possess more diverse evolutional origins compared to nosocomial strains (7,11,20,23,24), and they are predominantly carrying type IV SCCmec.…”

De novo design and in vivo activity of conformationally restrained antimicrobial arylamide foldamers

“…Recently, methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus epidermidis, vancomycinresistant enterococci (VRE), and ampicillin-resistant Escherichia coli have emerged as common nosocomial (hospitalacquired) infections (2)(3)(4). The escalating resistance to conventional agents has inspired a substantial research effort directed toward investigating the potential of antimicrobial peptides (AMPs).…”

Epidemiological Analysis of Staphylococcus aureus Isolated from Cows and the Environment of a Dairy Farm in Japan

“…Methicillin-resistant S. aureus (MRSA) strains of CC97 have been isolated from swine samples and so on. Many of these strains have been classified as SCCmec type IV, which appears to cause higher mobility than other SCCmec types [1]. Invasion and spread of SCCmec type IV strains in dairy barns may promote appearance of new MRSA strains adapted to cows.…”