Objectives:To analyze the antimicrobial resistance profiles(ARPs) of Staphylococcus aureus (SAU) isolated from primary medical institutions in Guangdong region from 2017 to 2021, to provide a basis for the use of antibiotics in the treatment of SAU infections.Methods:The SAU strains were collected from Guangdong region from 2017 to 2021 and inspected by Guangzhou Kingmed Center for Clinical Laboratory. Identification and antibiotic susceptibility tests were carried out by BioMérieux VITEK? MS microbial mass spectrometry system and Vitek-2 compact antibiotic susceptibility analysis system. Statistical analysis of the distribution and drug resistance of pathogenic bacteria were carried out using WHONET 5.6 software.Results:A total of 9713 non-replicating SAU were collected from 2017 to 2021, in which 4959 strains (51.06%)were identified as methicillin-resistant Staphylococcus aureus (MRSA). The main specimen sources of SAU were sputum 41.50%, wound secretions 31.87%, pus 8.87%, pharyngeal swabs 5.34%, and blood 4.74%. Sputum, urine, alveolar lavage fluid, blood, puncture fluid and pharyngeal swab MRSA isolation rate exceeded 50.00%. For SAU, the resistance to penicillin, oxacillin, erythromycin and clindamycin were all up to 50.00%. The isolation rate of multidrug-resistant methicillin-susceptible Staphylococcus aureus (MSSA) was 20.09%, and showed a decreasing trend yearly. The isolation rate of penicillin-sensitive MSSA (MSSA-PENS) showed an increasing trend. Among the MRSA strains, 41.51% were resistance to ten antibiotics, 12.54% were resistant to four antibiotics and 11.57% were resistant to five antibiotics. There were 105 ARPs of MRSA, 59 of which had more than two isolates, and 10 ARPs with more than 100 isolates. The dominant ARPs were ARPs Ⅶ: PEN/OXA/ERY/CLI/CIP; ARPs Ⅷ: PEN/OXA; ARPs Ⅸ: PEN/OXA/ERY/CLI; ARPs Ⅹ: PEN/OXA/TET/CIP/LEV/MXF/ERY/CLI/GEN. The isolation rate of MRSA on ARPs Ⅶ and Ⅸ were decreasing, while the isolation rate of MRSA strains on ARPs Ⅷ and Ⅹ were increasing.Conclusions:The rate of MRSA isolation in primary care institutions in Guangdong Province is high, the susceptibility of MSSA bacteria to antibiotics such as penicillin is increasing, and the APRs of MRSA are changing. The primary medical institutions need to strengthen nosocomial infection surveillance and drug resistance tests, as well as raise awareness of medical workers about prevention. Clinical departments should further make reasonable use of antibiotics to prevent the prevalence and outbreaks of SAU and MRSA.

Staphylococcus aureus (S. aureus) is one of the important human pathogens and causes both superficial and systemic infections. More importantly, the formation of S. aureus biofilms, a main cause of its pathogenicity and drug resistance, has been a critical challenge in clinical treatment. Carvacrol, a plant-based natural product, has gained great interest for therapeutic purposes due to its effective biological activity with low cytotoxicity. The present study aimed to investigate the effect of carvacrol on anti-biofilm activity. Growth curve analysis showed that applying a sub-inhibitory concentration of carvacrol (4 μg mL-1) was not lethal to S. aureus SYN; however, the inhibition rate of biofilm formation was as high as 63.6%, and the clearance rate of mature biofilms was as high as 30.7%. In addition, carvacrol effectively reduced the production of biofilm-associated extracellular polysaccharides and showed no effect on eDNA release. Furthermore, qPCR analysis revealed that carvacrol significantly down-regulated the expression of icaA, icaB, icaC, agrA, and sarA (P < 0.05). The in vivo efficacy of carvacrol against biofilm infection was further verified with a biological model of G. mellonella larvae. The results showed that carvacrol was non-toxic to the larvae and can effectively increase the survival rate of the larvae infected with S. aureus strain SYN.

Background:Staphylococcus haemolyticus is an opportunistic pathogen that belongs to coagulase-negative Staphylococci (CoNS). Increasing infection and multi-drug resistance cases caused by this strain have been reported and thus it poses a great health threat.Methods:The third-generation sequencing technology was performed on a S. haemolyticus SH-1 isolated from a clinical sample to analyze the drug resistance genes, which included vancomycin resistance related genes. In addition, antimicrobial susceptibility tests, transmission electron microscopy and Triton X-100 stimulated autolysis were conducted to understand its biological characteristics.Results:The study shows that this clinical isolate is a vancomycin intermediate-resistant strain. Genome comparison also revealed that WalK(N70K) and WalK(R280Q) mutations may contribute to the vancomycin resistant phenotype. Besides, S. haemolyticus SH-1 exhibit common features of thicker cell wall and decreased autolytic activity.Conclusion:S. haemolyticus SH-1 with WalKR mutations shows typical characteristics of vancomycin resistant strains. Combining the genome features and biological properties, our findings may provide important information for the understanding of the molecular mechanism of S. haemolyticus to vancomycin intermediate-resistance.

目的 对分离自血液样本的一株万古霉素中介耐药溶血葡萄球菌进行全基因组测序分析,探讨细菌对万古霉素中介耐药的可能机制.方法 通过第三代测序技术对一株万古霉素中介耐药溶血葡萄球菌临床分离株SH-1进行全基因组测序分析,进一步运用Blast对耐药基因和万古霉素耐药相关基因进行分析.VITEK 2 Compact全自动细菌鉴定及药敏分析系统分析SH-1的药物敏感性,E-test法检测SH-1对万古霉素的敏感性.结果 溶血葡萄球菌SH-1对青霉素、苯唑西林、替考拉宁等抗菌药物耐药,对万古霉素中介耐药.E-test检测结果显示SH-1对万古霉素最低抑菌浓度(MIC)值为8 μg/ml.SH-1全基因组大小为2 622 719 bp,GC含量有32.85％,含有2 556个编码序列,63个tRNA编码基因,以及16个rRNA基因编码的操纵子.SH-1属于ST97型耐甲氧西林溶血葡萄球菌,SH-1中有18个基因发生了突变,其中万古霉素耐药相关二元调控系统WalK(N70K)、WalK(R280Q)发生了点突变.结论 通过全基因组测序初步分析了一株溶血葡萄球菌SH-1菌株基因组特征,研究了 SH-1基因突变情况,二元调控系统WalK(N70K)、WalK(R280Q)发生了点突变可能是引起SH-1对万古霉素中介耐药的重要原因.