Journal of Jilin University(Medicine Edition) ›› 2024, Vol. 50 ›› Issue (2): 422-430.doi: 10.13481/j.1671-587X.20240215

• Research in clinical medicine • Previous Articles    

Comparison of drug resistance of MRSA clinical strains from respiratory tract and non-respiratory tract specimens and their molecular epidemiological characteristics

ERDEMUTU1,2,Yanyan WANG3,Yutong LI4,Guilin CHEN1(),Junrui WANG3()   

  1. 1.Department of Biology,School of Life Sciences,Inner Mongolia University,Hohhot 010050,China
    2.Department of Collaborative Innovation Center of Mongolian Medicine,Medical Innovation Center for Nationalities,Inner Mongolian Medical University,Hohhot 010110,China
    3.Department of Laboratory Medicine,Affiliated Hospital,Inner Mongolian Medical University,Hohhot 010050,China
    4.Department of Laboratory Medicine,School of First Clinical Medical Sciences,Inner Mongolian Medical University,Hohhot 010050,china
  • Received:2022-03-14 Online:2024-03-28 Published:2024-04-28
  • Contact: Guilin CHEN,Junrui WANG E-mail:guilinchen61@163.com;wangjunrui123@yeah.net

Abstract:

Objective To discuss the differences in drug resistance, molecular typing, and biofilm-forming abilities of methicillin-resistant Staphylococcus aureus (MRSA) isolated from respiratory and non-respiratory tract specimens. Methods A total of 100 MRSA strains were selected from clinical specimens of the hospitalized patients, and 50 MRSA strains were isolated from the respiratory specimens and another 50 MRSA strains were isolated from non-respiratory tract specimens. These 100 MRSA strains underwent an in vitro susceptibility test for 14 kinds of antimicrobial drugs, molecular typing was performed through multilocus sequence typing (MLST) and Staphylococcus aureus protein A (Spa) typing, and their biofilm-forming abilities were detected by crystal violet staining assay. Results The in vitro susceptibility tests results showed that all the 100 MRSA strains had high overall resistance rates of over 60.0% to penicillin, erythromycin, clindamycin, levofloxacin, ciprofloxacin, moxifloxacin, and tetracycline, while only 9.0% exhibited resistance to trimethoprim-sulfamethoxazole, and all the strains were susceptible to vancomycin, linezolid, tigecycline, and quinupristin/dalfopristin. Compared with those isolated from non-respiratory tract specimens,the MRSA strains isolated from respiratory tract specimens showed significantly higher resistance rates to moxifloxacin, levofloxacin, ciprofloxacin, tetracycline, and gentamicin (P<0.05). Among the 100 MRSA strains, 17 genotypes were identified, and the dominant types weve ST5-t2460 (26.0%), ST239-t030 (23.0%), and ST59-t437 (20.0%). In the MRSA from the respiratory tract specimens, the dominant types were ST5-t2460 (20.0%) and ST239-t030 (13.0%), followed by ST59-t437 (7.0%); in the non-respiratory tract specimens, 13 genotypes were found, and the dominant types were ST59-t437 (13.0%) and ST239-t030 (10.0%). All 100 MRSA strains were biofilm producers, among them the strong biofilm formers, moderate biofilm formers, and weak biofilm formers accounted for 2.0% (2/100), 24.0% (24/100), and 74.0% (74/100), respectively. The ST59-t437 clones had overall strong biofilm-forming abilities, and 60.0% (12/20) stains were moderate to strong biofilm formers. Conclusion The MRSA strains isolated from the respiratory tract specimens have a significantly higher overall resistance rate than those isolated from the non-respiratory tract specimens. The ST59-t437 and ST239-t030 genotypes are dominant clones common to both types of specimens, and ST59-t437 strains show strong biofilm-forming abilities, and ST239-t030 strains exhibit the strongest resistance.

Key words: Methicillin-resistant Staphylococcus aureus, Drug resistance, Molecular typing, Biofilm

CLC Number: 

  • R378.1