Abstract
Background The clonal repertoire of community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) strains appear to differ between hospitals and geographic locations. We aimed to study the molecular epidemiology of MRSA infections in our regional hospital in Israel. Methods A retrospective analysis of MRSA isolates from hospitalized patients, which underwent spa typing between 2012 and 2019. Mainly, MRSA-bloodstream isolates were typed. Isolates were grouped into healthcare-associated (HcA) or community-associated (CA). HcA were further divided into hospital-related or long-term care facility- (LTCF-) related. Several representatives underwent SCCmec typing. Results We analyzed 166 clinical MRSA isolates: 115 (70%) bloodstream, 42 (25%) wounds/abscesses, and 9 (5%) screening isolates. 145 (87%) were HcA, and 21 (13%) were CA. Common (72%) spa types were t002, t032, t008, t001, and t065. Eighty (55%) isolates were attributed to LTCFs and 65 isolates to our hospital, both showing similar spa types distribution. The most prevalent spa type among patients with HcA infection was t002 (50 isolates, 32%), followed by t032, t065, t578, t008, and t001. Most (88/115, 77%) bloodstream infections (BSIs) were HcA, typically occurring in the same facility in which the infection was acquired. In 27 cases (23%), the BSI developed in the community setting, and in half of these cases, a previous healthcare system exposure was evident. Conclusions The MRSA clonal population in this longitudinal study was stable and consisted mainly of molecular lineages widespread in Europe. SCCmec-IV strains play a major role in causing MRSA infections in the healthcare settings, especially in LTCFs. Community-acquired MRSA BSIs without any previous healthcare exposure are still relatively rare.
Highlights
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important pathogens causing severe community- and healthcare-associated (HcA) infections [1]
Most of the analysis focused on MRSA strains, and the overall clonal data were in accordance with previous reports: the major MRSA spa types in our study were t002, t032, and t008, similar to reports from other countries in Europe [3]; to the Israeli Ministry of Health reports of 2016–2017 [4, 5]; and to a recent large community-based survey from Israel [7]
Most (87%) of the MRSA isolates were HcA, and only 21 cases were CA. spa type t002 was most commonly encountered, causing 56 (34%) of all MRSA infections. is type is commonly regarded as HcA-MRSA, usually bearing Staphylococcal chromosomal cassette mec (SCCmec)-II, and 89% of this spa type was HcA by our definitions
Summary
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most important pathogens causing severe community- and healthcare-associated (HcA) infections [1]. Methicillin resistance is coded on the Staphylococcal chromosomal cassette mec (SCCmec) element. HcA-MRSA infections were traditionally associated with SCCmec types I, II, and III; but in the last two decades, communityassociated- (CA-) MRSA infections have emerged, resulting in skin and soft tissue, as well as invasive infections, among healthy young populations with no traditional risk factors for MRSA infections. Ese CA-MRSA clones are associated with SCCmec types IV and V, which are smaller cassettes that lack resistance genes to non-beta-lactam antimicrobials. The most prevalent Staphylococcus aureus protein A (spa) types were t032, t008, and t002 in Europe; t037 and t002 in Asia; and t008, t002, and t242 in America. Several spa types are strictly related to SCCmec-I and II (such as t001), several are strongly related to SCCmec-IV (such as t032 and t008), and several may be related to both types of SCCmec (such as t002, which may be typed as SCCmec-I, II, III, IV, and V) [3]
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