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Abstract Staphylococcus aureus is a relevant pathogen in bloodstream infections (BSI), and the emergency of the COVID-19 pandemic increased its antimicrobial resistance. S. aureus isolates from BSI (September/2019 - March/2021) were analyzed phenotypically and molecularly, in addition to the clinical features of the patients. Of 88 S. aureus isolates recovered from 85 patients, 25 were isolated before the pandemic and 63 during it, and 16 were from patients with COVID-19. A rate of 45.5% of methicillin-resistant isolates (MRSA) were found, and 5% of them were ceftaroline susceptible dose-dependent. Daptomycin non-susceptibility was observed in 9.1% of isolates. The USA800/ST5/SCCmecIV lineage was prevalent among MRSA isolates (41.8%). Besides, 30.2% of the isolates were associated with community-associated MRSA (CA-MRSA) genotypes. There was a significant impact on the resistance rates for cefoxitin, clindamycin and erythromycin among S. aureus isolates from BSI in COVID-19 patients and association with the previous use of azithromycin by them (p

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.

Staphylococcus aureus is a relevant pathogen in bloodstream infections (BSI), and the emergency of the COVID-19 pandemic increased its antimicrobial resistance. S. aureus isolates from BSI (September/2019 - March/2021) were analyzed phenotypically and molecularly, in addition to the clinical features of the patients. Of 88 S. aureus isolates recovered from 85 patients, 25 were isolated before the pandemic and 63 during it, and 16 were from patients with COVID-19. A rate of 45.5% of methicillin-resistant isolates (MRSA) were found, and 5% of them were ceftaroline susceptible dose-dependent. Daptomycin non-susceptibility was observed in 9.1% of isolates. The USA800/ST5/SCCmecIV lineage was prevalent among MRSA isolates (41.8%). Besides, 30.2% of the isolates were associated with community-associated MRSA (CA-MRSA) genotypes. There was a significant impact on the resistance rates for cefoxitin, clindamycin and erythromycin among S. aureus isolates from BSI in COVID-19 patients and association with the previous use of azithromycin by them (p < 0.05). A clonal alternation and an increase in the emergence of CA-MRSA lineages were also found, highlighting the importance of constant microbiological surveillance. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]