血液来源人葡萄球菌生物被膜形成能力及耐药性的研究

Study on biofilm formation ability and antibiotic resistance of blood-derived Staphylococcus hominis

目的探究人葡萄球菌生物被膜能力和耐药性,为预防与治疗提供理论依据。方法收集临床分离血液来源人葡萄球菌,琼脂稀释法检测16种抗菌药物的最小抑菌浓度(MIC),通过耐苯唑西林表型和mecA基因型以准确区分耐甲氧西林人葡萄球菌(MRSHo)和甲氧西林敏感人葡萄球菌(MSSHo),比较二者在耐药性上的差异;体外微孔板黏附实验(TCP)测定生物被膜,并分析其对耐药性的影响。结果收集菌株共计55株,药物耐药率由高到低分别为青霉素92.73%、红霉素87.27%、苯唑西林83.64%、克林霉素67.27%、复方磺胺甲噁唑65.45%、环丙沙星47.27%、左氧氟沙星47.27%、四环素41.82%、莫西沙星34.55%、利福平16.36%和庆大霉素10.91%及万古霉素、利奈唑胺、普丁/达福、呋喃妥因和替加环素0.00%,无耐药株检出。46株(83.6%)mecA阳性为MRSHo,与MSSHo相比MRSHo更易对青霉素、四环素、奎诺酮类及复方磺胺甲噁唑耐药,差异有统计学意义(P<0.05)。35株(63.6%)可产生物被膜,生物被膜阴阳性菌株组间在16种抗菌药物耐药性比较,差异无统计学意义(P>0.05)。结论临床分离血液来源人葡萄球菌易产生物被膜、甲氧西林耐药率高、MRSHo常为多重耐药。

Objective To study the characteristics of biofilm formation ability and drug resistance of Staph ylococcus hominis,and to provide the basis for prevention and treatment of the infection. Methods Staphylo coccus hominis were isolated from positive blood culture and identified by automatic microbiological identifica tion system. Minimal inhibitory concentration （MIC） of 16 antibiotics were determined by the agar dilution method. The mecA gene was detected by PCR for differentiation of Methicillin resistant Staphylococcus homi nis （MRSHo）and Methicillin susceptive Staphylococcus hominis（MSSHo）, and differences in antimicrobial susceptibility between MRSHo and MSSHo were analyzed. Microtite Plate Assay （TCP） was used to evaluate biofilm formation capacity of Staphylococcus hominis, and the differences in antimicrobial susceptibility be tween biofilm forming and non-biofilm strains were analyzed. Results A total of 55 Staphylococcus hominis strains were isolated from positive blood cultures. The antimicrobial resistance rates were penicillin（92.73% ）, erythromycin （ 87. 27 %）, oxacillin （ 83. 64 % ）, clindamycin （ 67. 27 % ）, trimethoprim/sulpham-ethoxazole （65.45%） ,ciprofloxacin （47.27%）,lavofloxacin （47.27%）,tetracycline （41.82%）,moxifloxacin （34.55%）, rifampicin （16. 36%） and gentamicin （10.91%）,respectively,while the resistance rates of all of vancomycin, linezolid, quinupristin/dalfopristin, nitrofurantion, and tigecycline were 0. 00%. Among these strains, 46 （83.64%） isolates were MRSHo and 9 isolates were MSSHo. There were significant differences in antimicro- bial susceptibility between MRSHo and MSSHo. For ciprofloxacin,lavofloxacin,moxifloxacin,penicillin,tetra- cycline,trimethoprim/sulphamethoxazole,MRSHo had a higher resistance rates than MSSHo （P〈0.05）. Re- sults indicated that 35 isolates were biofilm producers （63.6% ）. There was no significant difference in antimi-crobial susceptibility between biofilm forming and non-biofilm strains （P〉0.05）. Conclusion The analyzed Staphylococcus hominis isolates have a strong biofilm formation ability and high prevalence of methicillin re- sistance and multiple resistance.