耐甲氧西林金黄色葡萄球菌耐药基因及消毒剂耐药相关基因研究

Research on resistance genes of methicillin-resistant Staphylococcus aureus and disinfectant resistancerelated genes

目的 探讨耐甲氧西林金黄色葡萄球菌(Methicillin-resistant Staphylococcus aureus,MRSA)耐药基因及消毒剂耐药相关基因,以期为临床感染防控和新型治疗策略的制定提供依据。方法 收集本院检验科分离保存的105株MRSA,将其分为医院获得性MRSA(HA-MRSA)和社区获得性MRSA(CA-MRSA),对比分析两组MRSA菌株对常见抗菌药物的耐药率,采用聚合酶链反应(PCR)方法检测两组菌株耐药基因及消毒剂耐药相关基因携带情况。按照是否携带消毒剂耐药相关基因将其分组,对比两组菌株的耐药率。结果 105株MRSA中,各标本来源占比如下:伤口分泌物38.10%,呼吸道分泌物14.29%,尿液11.43%,肺泡灌洗液9.52%,血液7.62%,胸腔积液6.67%,腹水和胸水各4.76%,关节液2.86%。科室来源占比:烧伤科23.81%,ICU 17.14%,呼吸内科12.38%,骨外科10.48%,儿内科8.57%,神经内科、普外科各6.67%,急诊科4.76%,胸外科、产科各2.86%,泌尿外科、乳腺外科各1.90%。105株MRSA中,HA-MRSA 65株(61.90%),CA-MRSA 40株(38.10%)。两者对青霉素G、苯唑西林均耐药,对利奈唑胺、万古霉素、替考拉宁均敏感。HA-MRSA对红霉素、克林霉素等多种抗生素的耐药率高于CA-MRSA,尤其四环素、庆大霉素、利福平的耐药率差异有统计学意义(P<0.05)。HA-MRSA耐药基因携带率如下:mecA 100%,tetM 70.77%,aac(6')/aph(2') 46.15%,aph3'-Ⅲ30.77%,ermA 47.69%,ermC 35.38%;CA-MRSA中,mecA 100%,tetM 50%,aac(6')/aph(2') 25%,aph3'-Ⅲ12.5%,ermA 27.5%,ermC 17.5%。HA-MRSA的多个耐药基因携带率高于CA-MRSA,差异显著(P<0.05)。HA-MRSA消毒剂耐药基因qacA/B携带率50.77%,CA-MRSA 25%,差异显著(P<0.05)。携带qacA/B基因的MRSA菌株(n=43)与未携带qacA/B基因的MRSA菌株(n=62)对青霉素G、苯唑西林耐药率为100%,对利奈唑胺、万古霉素、替考拉宁敏感度为100%。携带qacA/B基因的菌株对红霉素、克林霉素等多种抗生素的耐药率更高,差异显著(P<0.05)。结论 本次研究中,MRSA菌株主要分离自伤口分泌物标本,来源于烧伤科。HA-MRSA对多种抗生素的耐药率高于CA-MRSA,HA-MRSA的多个耐药基因携带率高于CA-MRSA,携带qacA/B基因的菌株对红霉素、克林霉素等多种抗生素的耐药率更高。

Objective To explore the resistance genes of Methicillin-resistant Staphylococcus aureus(MRSA)and the genes related to disinfectant resistance,with the aim of providing a theoretical basis for the prevention and control of clinical infections and the formulation of new treatment strategies.Methods105 strains of MRSA isolated and preserved in the clinical laboratory of our hospital were selected as the research subjects for this study.They were divided into hospital-acquired MRSA(HA-MRSA)and community-acquired MRSA(CA-MRSA).The resistance rates of the two groups of MRSA strains to common antibacterial drugs were compared and analyzed.The polymerase chain reaction(PCR)method was used to detect the carrying status of resistance genes and disinfectant resistance-related genes in the two groups of strains.They were grouped according to whether they carried disinfectant resistance-related genes,and the drug resistance rates of the two groups of strains were compared.Results Among the 1o5 strains of MRSA,the proportions of the sources of each specimen were as follows:38.10%from wound secretions,14.29%from respiratory secretions,11.43%from urine,9.52%from alveolar lavage fluid,7.62%from blood,6.67%from pleural effusion,4.76%each from ascites and pleural fluid,and 2.86%from joint fluid.The proportions of the sources of departments were as follows:23.81%from the department of burns,17.14%from the ICU,12.38%from the department of respiratory medicine,10.48%from the department of orthopedic surgery,8.57%from the department of pediatric internal medicine,6.67%each from the department of neurology and the department of general surgery,4.76%from the emergency department,2.86%each from the department of thoracic surgery and the department of obstetrics,and 1.90%each from the department of urology and the department of breast surgery.Among the 105 strains of MRSA,there were 65 strains of HA-MRSA(61.90%)and 40 strains of CA-MRSA(38.10%).Both were resistant to penicillin G and oxacillin,and were sensitive to linezolid,vancomycin and teicoplanin.The resistance rate of HA-MRSA to various antibiotics such as erythromycin and clindamycin was higher than that of CA-MRSA.Especially,the differences in the resistance rates of tetracycline,gentamicin and rifampicin were significant(P<0.05).The carrying rates of resistance genes in HA-MRSA were as follows:mecA 100%,tetM 70.77%,aac(6)/aph(2)46.15%,aph3-II 30.77%,ermA 47.69%,ermC 35.38%;In CA-MRSA,mecA 100%,tetM 50%,aac(6)/aph(2)25%,aph3-II 12.5%,ermA 27.5%,ermC 17.5%.The carrying rates of multiple resistance genes in HA-MRSA were higher than those in CA-MRSA,and the difference was significant(P<0.05).The carrying rate of the disinfectant resistance gene qacA/B in HA-MRSA was 50.77%,and in CA-MRSA it was 25%.The difference was significant(P<0.05).The resistance rates of MRSA strains carrying the qacA/B gene(n=43)and those not carrying the qacA/B gene(n=62)to penicillin G and oxacillin were 100%,and the sensitivity to linezolid,vancomycin and teicoplanin was 1oo%.The resistance rates of the strains carrying the qacA/B gene to various antibiotics such as erythromycin and clindamycin were higher,and the difference was significant(P<0.05).Conclusion In this study,MRSA strains were mainly isolated from wound secretion specimens and originated from the department of burns.The resistance rate of HA-MRSA to multiple antibiotics was higher than that of CA-MRSA.The carrying rate of multiple resistance genes of HA-MRSA was higher than that of CA-MRSA.The resistance rate of the strains carrying the qacA/B gene to various antibiotics such as erythromycin and clindamycin was higher.