95株临床分离耐甲氧西林金黄色葡萄球菌耐药基因分布及其与抗菌药物耐药相关性

Correlation between distribution of drug-resistance genes and antibacterial drug resistance in 95 clinical isolates of methicillin-resistant Staphylococcus aureus

    摘要
  • 摘要:
    目的 探讨临床分离的耐甲氧西林金黄色葡萄球菌(MRSA)的耐药基因分布特征及其与抗菌药物耐药的相关性。
    方法 收集95株来自上海市第八人民医院2023年11月-2024年7月临床分离的MRSA, 采用法国梅里埃自动化药敏系统鉴定其抗菌药物耐药情况; 采用聚合酶链反应(PCR)法及琼脂糖凝胶电泳法测定95株MRSA共13个耐药基因(mecA、gyrA、gyrB、ermA、ermB、ermC、aph(3')-IIIa、aac(A)-aph(D)、NorA、grlA、blaZ、tetK、tet38)的分布情况, 通过χ2检验和Pearson相关系数分析其与临床常用抗菌药物的相关性。
    结果 所有菌株均携带mecA、gyrA、gyrB三个基因, 主要耐药基因谱为mecA-gyrB-gyrA-grlA-ermA-tet38-NorA(26.32%)。药敏结果显示95株MRSA对β-内酰胺类抗菌药物100.00%耐药; 对红霉素、左氧氟沙星、莫西沙星、克林霉素的耐药率较高, 均超过60.00%;对万古霉素等糖肽类抗菌药物100.00%敏感。抗菌药物耐药的MRSA在红霉素耐药基因ermA、庆大霉素耐药基因aph(3')-IIIa和aac(A)-aph(D)、四环素耐药基因tetK的携带率中均明显高于抗菌药物敏感的菌株, 差异均有统计学意义(P < 0.05)。而其他耐药基因ermB、ermC、tet38、NorA、grlA在耐药和敏感菌株中的携带率差异均无统计学意义。耐药基因携带数与抗菌药物耐药数之间存在中等程度的正相关关系。
    结论 本研究揭示了MRSA以多重耐药为特征的耐药模式及与耐药基因的分布规律, 为指导临床合理用药提供分子依据。

     

    Abstract:
    OBJECTIVE To investigate the distribution characteristics of drug-resistance genes in clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and their correlation with antibacterial drug resistance.
    METHODS A total of 95 MRSA strains isolated clinically from Nov. 2023 to Jul. 2024 at Shanghai 8th People's Hospital were collected. The antibacterial drug resistance of these strains was identified through the French bioMerieux automated susceptibility testing system. PCR and agarose gel electrophoresis were employed to determine the distribution of 13 drug-resistance genes (mecA, gyrA, gyrB, ermA, ermB, ermC, aph(3)-IIIa, aac(A)-aph(D), NorA, grlA, blaZ, tetK, tet38) in the 95 MRSA strains. The correlation between these genes and clinically commonly used antibacterial drugs was analyzed with the χ2 test and Pearson correlation coefficient.
    RESULTS All strains carried the three genes mecA, gyrA, and gyrB. The predominant drug-resistance gene profile was mecA-gyrB-gyrA-grlA-ermA-tet38-NorA (26.32%). The susceptibility test results showed that all 95 MRSA strains were 100.00% resistant to β-lactam antibacterial drugs. They exhibited high resistance rates to erythromycin, levofloxacin, moxifloxacin and clindamycin, all exceeding 60.00%. And they were 100.00% sensitive to glycopeptide antibacterial drugs like vancomycin. The carriage rates of the erythromycin resistance gene ermA, gentamicin resistance genes aph(3)-IIIa and aac(A)-aph(D) and tetracycline resistance gene tetK were significantly higher in antibacterial drug-resistant MRSA strains than in antibacterial drug-sensitive strains, with statistically significant differences (P < 0.05). However, there were no statistically significant differences in the carriage rates of other drug-resistance genes, including ermB, ermC, tet38, NorA and grlA, between resistant and sensitive strains. There was a moderate positive correlation between the number of drug-resistance genes carried and the number of antibacterial drugs to which resistance was exhibited.
    CONCLUSIONS This study reveals the drug-resistance pattern of MRSA characterized by multidrug resistance and its distribution pattern of drug-resistance genes, providing a molecular basis for guiding rational clinical drug use.

     

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