Infection and Drug Resistance (Jan 2023)

Resistance and Molecular Characteristics of Methicillin-Resistant Staphylococcus aureus and Heterogeneous Vancomycin-Intermediate Staphylococcus aureus

  • Liang J,
  • Hu Y,
  • Fu M,
  • Li N,
  • Wang F,
  • Yu X,
  • Ji B

Journal volume & issue
Vol. Volume 16
pp. 379 – 388

Abstract

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Jin Liang,1,* Yuanfang Hu,1,* Mingxia Fu,2 Na Li,1 Fengxia Wang,1 Xiaojun Yu,1 Bing Ji1 1Department of Laboratory Medicine, Binzhou Medical University Hospital, Binzhou, People’s Republic of China; 2Department of Laboratory Medicine, Binzhou People’s Hospital, Binzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Bing Ji, Email [email protected]: To investigate the molecular epidemiology of Staphylococcus aureus (S. aureus) isolated from patients in the Yellow River Delta region and to construct antibiotic resistance profiles in different genetic backgrounds.Methods: Antibiotics susceptibility testing, staphylococcal protein A (spa) typing and accessory gene regulator (agr) typing were performed for all the 204 strains. Isolates with the positive mecA gene and heterogeneous vancomycin-intermediate S. aureus (hVISA) were subjected to multilocus sequence typing (MLST) and Staphylococcal chromosomal cassettes mec (SCCmec) typing.Results: Thirty-nine MRSA strains were identified by mecA gene. Twenty-two hVISA isolates including 9 MRSA and 13 methicillin-sensitive S. aureus (MSSA) strains were confirmed, the rest isolates (n = 182) were vancomycin-susceptible S. aureus (VSSA). 94.9% of MRSA and 63.6% of hVISA belonged to agrI. Fifty-seven distinct spa types including 5 novel types were mainly t309 (30.9%), t078 (11.8%) and t437 (11.8%). Fourteen sequence types (STs) containing 3 new STs were classified into 3 clone complexes (CCs) and 7 singletons among MRSA and hVISA isolates. Most MRSA isolates (87.2%) belonged to type Ⅳ SCCmec.Conclusion: The predominant genotype among MRSA population was ST59-t437-agrI-IVa (53.8%), followed by ST72-t2431-agrI-IVF (15.4%). ST72 and CC5 (ST5/965/7197) were the most common hVISA clones. Both CC59 (ST59/7437) and ST72 clones were resistant to erythromycin and clindamycin among MRSA population. Strains of MSSA with phenotypic hVISA (MS-hVISA) exhibited a striking genetic diversity accompanied by the diversification of drug resistance patterns.Keywords: Staphylococcus aureus, heterogeneous vancomycin-intermediateS. aureus, accessory gene regulator, multilocus sequence typing, erythromycin

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