Pandemic clone USA300 in a Brazilian hospital: detection of an emergent lineage among methicillin-resistant Staphylococcus aureus isolates from bloodstream infections

Abstract

Background Staphylococcus aureus is one of the leading causes of bloodstream infections (BSI) worldwide. In Brazil, the hospital-acquired methicillin-resistant S. aureus USA100/SCCmecII lineage replaced the previously well-established clones. However, the emergence of community-associated (CA) MRSA lineages among hospitalized patients is an increasing issue. Methods Consecutive S. aureus isolates recovered from BSI episodes of patients admitted between January 2016 and December 2018 in a Brazilian teaching hospital were tested for antimicrobial resistance, their genotypic features were characterized, and the clinical characteristics of the patients were evaluated. Results A total of 123 S. aureus isolates were recovered from 113 patients. All isolates were susceptible to linezolid, teicoplanin and vancomycin and 13.8% were not susceptible to daptomycin. Vancomycin MIC50 and MIC90 of 2 mg/L were found for both MRSA and MSSA isolates. The MRSA isolation rate was 30.1% (37/123), and 51.4% of them carried the SCCmec type II, followed by SCCmecIV (40.5%). Among the 37 MRSA isolates, the main lineages found were USA100/SCCmecII/ST5 and ST105 (53.7%) and USA800/ST5/SCCmecIV (18.9%). Surprisingly, six (16%) CA-MRSA isolates, belonging to USA300/ST8/SCCmecIVa that carried PVL genes and the ACME cassette type I, were detected. These six patients with USA300 BSI had severe comorbidities, including cancer, and most had a Charlson score ≥ 5; furthermore, they were in wards attended by the same health professionals. MRSA isolates were associated with hospital acquired infections (p = 0.02) in more elderly patients (p = 0.03) and those diagnosed with hematologic cancer (p = 0.04). Among patients diagnosed with MRSA BSI, 19 (54.3%) died. Conclusions The pandemic MRSA USA300 was detected for the first time in the Brazilian teaching hospital under study, and its cross-transmission most probably occurred between patients with BSI. This lineage may already be circulating among other Brazilian hospitals, which highlights the importance of carrying out surveillance programs to fight multidrug resistant and hypervirulent isolates.

Hospital‐Related Lineage of USA300 Methicillin‐Resistant Staphylococcus aureus (MRSA) to Cause Bacteremia in Iran

“…This emergence has been reported regionally, as in Iran, the UAE, Australia, Kuwait Japan, Ireland, and Korea [ 6 , 11 ]. In a 2022 study conducted by Augusto et al on 123 S. aureus isolates recovered from a bloodstream in Brazil, three main lineages were USA800/ST5/SCC mec IV, ST105, and USA100/SCC mec II/ST5 [ 1 ]. Similarly, in a study in Chinese hospitals, Song et al reported a high frequency of ST5-SCC mec IV/t002 [ 25 ].…”

“…Staphylococcus aureus is an important nosocomial pathogen which is known to be responsible for bloodstream infections (BSI) [ 1 ]. Considering the recently reported evidence, S .…”

“…Therefore, several researchers have recently focused on understanding the genotypes of SAB that are responsible for both virulence and antibiotic resistance [ 2 ]. Historically, it is well understood that the pathogenesis of SAB is linked to the expression of various virulence and antibiotic resistance determinants [ 1 , 2 ]. However, in recent decades, certain genotypes of SAB have been documented to cause significant mortality rates, complications, and healthcare costs and may play a critical role in the pathogenesis of S. aureus , especially in patients with underlying diseases [ 2 ].…”

“…Over recent years, the dissemination of various S. aureus clones has been described in healthcare setting environments. USA300 (ST8-SCC mec IV/t008) is a pathogen found in North America in the general population and hospitals and is characterized by its wide genetic diversity, rapid dissemination, and association with invasive infections, such as hematogenous complications and bacteremia [ 1 , 5 ]. Literature has indicated that USA300 was isolated worldwide and particularly predominant in Spain, Canada, Switzerland, Australia, Iran, and the UAE [ 6 ].…”

High levels of biofilm formation and prevalence of biofilm-associated genes in Staphylococcus aureus isolated from food handlers in Brazil

“…These occurrences can be explained by the capacity of S. aureus strains to acquire a diversity of virulence genes, such as enterotoxin, bio lm and toxin genes, which contribute to its pathogenicity and infection. In Brazil, this pathogen has been one of the main ones associated with both healthcare-associated and foodborne infections (Cavalcante et al 2021a;Augusto et al 2022).…”