There have been no reports regarding the molecular characteristics, virulence features, and antibiotic resistance profiles of Staphylococcus aureus (S. aureus) from Hainan, the southernmost province of China. Two hundred twenty-seven S. aureus isolates, consisting of 76 methicillin-resistant S. aureus (MRSA) and 151 methicillin-susceptible S. aureus (MSSA), were collected in 2013–2014 and 2018–2019 in Hainan, and investigated for their molecular characteristics, virulence genes, antibiotic resistance profiles and main antibiotic resistance genes. Forty sequence types (STs) including three new STs (ST5489, ST5492 and ST5493), and 79 Staphylococcal protein A (spa) types were identified based on multilocus sequence typing (MLST) and spa typing, respectively. ST398 (14.1%, 32/227) was found to be the most prevalent, and the prevalence of ST398-MSSA increased significantly from 2013 to 2014 (5.5%, 5/91) to 2018–2019 (18.4%, 25/136). Seventy-six MRSA isolates were subject to staphylococcus chromosomal cassette mec (SCCmec) typing. SCCmec-IVa was the predominant SCCmec type, and specifically, ST45-SCCmec IVa, an infrequent type in mainland China, was predominant in S. aureus from Hainan. The antibiotic resistance profiles and antibiotic resistance genes of S. aureus show distinctive features in Hainan. The resistant rates of the MRSA isolates to a variety of antibiotics were significantly higher than those of the MSSA isolates. The predominant erythromycin and tetracycline resistance genes were ermC (90.1%, 100/111) and tetK (91.8%, 78/85), respectively. Eleven virulence genes, including the Panton-Valentine leukocidin (pvl) and eta, were determined, and the frequency of eta and pvl were found to be 57.3 and 47.6%. Such high prevalence has never been seen in mainland China before. S. aureus isolates in Hainan have unique molecular characteristics, virulence gene and antibiotic resistance profiles, and main antibiotic resistance genes which may be associated with the special geographical location of Hainan and local trends in antibiotic use.

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Molecular characteristics and virulence gene profiles of Staphylococcus aureus isolates in Hainan, China

Prevalence and characterization of Staphylococcus aureus isolates from subclinical bovine mastitis in southern Xinjiang, China.

Methicillin resistant Staphylococcus aureus strains pose a serious treatment problem because of their multi-drug resistance (MDR). In staphylococcal strains, resistance to macrolides, lincosamides, and streptogramin B (MLSB) correlates with resistance to methicillin. The rapid transmission of erm genes responsible for MLSB resistance has strongly limited the clinical application of traditional macrolides such as erythromycin. On the other hand, in the age of increasing insensitivity to antibiotics the idea of implementing a therapy based on older generation drugs brings hope that the spread of antibiotic resistance will be limited. A thorough understanding of the resistance mechanisms contributes to design of antibiotics that avoid bacterial insensitivity. This review highlights the mechanisms of action of macrolides and mechanism of resistance to these antibiotics among Staphylococcus aureus.

Mechanisms of Resistance to Macrolide Antibiotics among Staphylococcus aureus.

The prevalence of drug-resistant and virulent Staphylococcus spp. in a municipal wastewater treatment plant and their spread in the environment

Staphylococcus aureus (SA) belonging to the clonal complex 398 (CC398) took a special place within the species due to its spread throughout the world. SA CC398 is broadly separated in two subpopulations: livestock-associated methicillin-resistant SA (MRSA) and human-associated methicillin-susceptible SA (MSSA). Here, we reviewed the global epidemiology of SA CC398 in human clinical infections and focused on MSSA CC398. The last common ancestor of SA CC398 was probably a human-adapted prophage φSa3-positive MSSA CC398 strain, but the multiple transmissions between human and animal made its evolution complex. MSSA and MRSA CC398 had different geographical evolutions. Although MSSA was present in several countries all over the world, it was mainly reported in China and in France with a prevalence about 20%. MSSA CC398 was frequently implicated in severe infections such as bloodstream infections, endocarditis, and bone joint infections whereas MRSA CC398 was mainly reported in skin and soft tissue. The spread of the MSSA CC398 clone is worldwide but with a heterogeneous prevalence. The prophage φSa3 played a crucial role in the adaptation to the human niche and in the virulence of MSSA CC398. However, the biological features that allowed the recent spread of this lineage are still far from being fully understood.

https://www.mdpi.com/2076-2607/8/11/1737/pdf

Human Infection of Methicillin-Susceptible Staphylococcus aureus CC398: A Review

Background The rate of methicillin-resistant Staphylococcus aureus (MRSA) among the total of S. aureus isolates decreased to 35.3% in 2017 in China. It is unclear whether the molecular characteristics of S. aureus isolates have changed as the rate decreased. Objective This study aimed to investigate the molecular characteristics and virulence genes profile of S. aureus isolates causing bloodstream infection and analyze the correlation between the prevalence rates of the common sequence types and MRSA. Methods A total of 112 S. aureus strains from eight hospitals of four cities, including 32 MRSA isolates, were identified and evaluated through multilocus sequence typing, spa typing, and determination of virulence genes. Results Twenty-five STs were identified, of which ST5 (21.4%) was the most prevalent, whereas the prevalence of ST239 correlated with the rate of MRSA among all S. aureus isolates. Forty-six spa types were identified, of which t2460 (14.3%) was the most common. clfa, hla, seb, fnbA and hlb were the prevailing virulence genes. 81.3% MRSA and 45.0% methicillin-sensitive S. aureus (MSSA) isolates harbored six or more tested virulence genes. ST5-t2460, seldom noted in bloodborne S. aureus isolates in China, was the most common clone. The prevalence of harboring six or more virulence genes in ST5-t2460 and ST188-t189 were 93.8% and 8.3%, respectively. Conclusion ST5-t2460 was the most common clone in S. aureus causing bloodstream infection followed by ST188-t189, which had never been noted in China before. Moreover, ST5-t2460 harbored more virulence genes than ST188-t189, and the prevalence of ST239 clone decreased with the proportion of MRSA among all S. aureus isolates.

Chenglin Li

Papers

Molecular characteristics and virulence gene profiles of Staphylococcus aureus isolates in Hainan, China

Molecular characteristics and virulence gene profiles of Staphylococcus aureus causing bloodstream infection.