Clonality, virulence genes, and antibiotic resistance of Staphylococcus aureus isolated from blood in Shandong, China

Abstract

Background Bloodstream infection (BSI) caused by Staphylococcus aureus (S. aureus) can be life-threatening and pose a great challenge to infection control and clinical treatment. However, little information exists regarding the characterization of S. aureus in BSI patients in Shandong, China. To identify the clonality, virulence genes, and antibiotic resistance of S. aureus in blood, a total of 101 nonrepetitive blood isolates were collected. The antibiotic resistance phenotypes were determined, and virulence genes were analyzed with polymerase chain reaction (PCR). Finally, the genetic relatedness was investigated with Staphylococcus chromosomal cassette mec (SCCmec) typing for methicillin-resistant S. aureus (MRSA) isolates, Staphylococcal protein A (spa), and multilocus sequence typing (MLST) for all of 101 isolates. Results Of the 101 S. aureus isolates, 24 MRSA isolates and 77 methicillin-susceptible S. aureus (MSSA) isolates were identified. Overall, MRSA isolates had higher resistance rates than MSSA isolates when exposed to any of the 15 antibiotics tested in this study except for trimethoprim/sulfamethoxazole. Among the 17 virulence genes tested in this study, hla, hld, and hlg could be detected in all isolates. MRSA isolates were more likely to carry seb and hlb genes, while MSSA isolates were more likely to carry seg and sei genes. Thirty-five sequence types (STs) and 49 spa types were identified, of which ST59-t437 and ST398-t571 were the most abundant. These two genotypes were also the most abundant ST-spa types in MRSA and MSSA isolates, but their abundances shifted over time, with ST398-t571 being the predominant genotype from 2016 to 2017, and ST59-t437 from 2018 to 2020. Besides, all the ST59-t437 isolates harbored hlgb gene, whereas most (88.9%) ST398-t571 did not. In addition, twenty-four MRSA isolates were subject to SCCmec typing. SCCmec IVa was the most prevalent SCCmec type, and all the ST59-t437 MRSA isolates were SCCmec IVa. We also observed 15 new STs, and some of them were MRSA. Conclusion These findings provide additional observations and epidemiological data for blood S. aureus isolates, which can improve future infection-control measures and aid in potential clinical treatments in hospitals and other clinical settings.

Investigation of SCCmec Types using the Real Time PCR Method in Cefoxitin-Resistant Staphylococcus aureus Isolates

“…All of the isolates were found susceptible to linezolid, teicoplanin, and vancomycin, and 65.5% was resistant to erythromycin, and they were similar to the literature [23][24][25][26].…”

Spectrum of Virulence Factors in Clinical Isolates of Staphylococcus aureus and Prevalence of SCCmec Types in Methicillin-Resistant Staphylococcus aureus in a Tertiary Care Center

“…41 Other investigators from other countries have found the prevalence of pvl gene to be ranging from 11.3% to 42.8%. 2,3,8,20,36,40,42 In this study, the adhesion (fnbA, fnbB, and clfA) and cytolysins (hlb and hla) genes occurred more frequently particularly among isolates from exudative specimens. This suggests that adherence and cytotoxicity are majorly operative in skin and skin and soft tissue infections by Staphylococcus aureus In this study, there is no significant difference in the distribution of virulence genes among MRSA and MSSA.…”

“…Previous studies have found wide variation (0.2% to 94.4%) in the occurrence of the eta gene in Staphylococcus aureus. 8,10,20,[34][35][36] The prevalence of tst gene ranged between 5% and 34.6% in various published reports. 8,32,35,[37][38][39][40] Pvl gene was detected in 6.7% (9/133) and all were from isolates recovered from wound exudates.…”

“…6 Staphylococcus aureus produces exotoxins 7 that are cytolytic which form β-barrel pores in the plasma membrane, leading to leakage of the cell contents and lysis cytolysins include α-hemolysin, β-hemolysin, γ-hemolysin, leukocidin, and Panton-Valentine leukocidin (PVL). 8 The hla gene codes for the α-hemolysin that is lethal to human epithelial cells and a primary agent in skin infections. The beta-hemolysin, encoded by the hlb gene, is a sphingomyelinase and is presumed to have a role in lung injury and pneumonia.…”

Changes in molecular characteristics and antimicrobial resistance of invasive Staphylococcus aureus infection strains isolated from children in Kunming, China during the COVID-19 epidemic

“…The molecular characteristics of prevalent S. aureus strains also vary over time. Wang et al (2021a) found that the S. aureus strain responsible for bloodstream infection was ST398-t571 from 2016 to 2017 and ST59-t437 from 2018 to 2020 in Shandong Province, China. Thus, it is important to continuously monitor the prevalence of S. aureus in various regions.…”