氟喹诺酮类药物对动物源MRSA和MSSA的防耐药变异浓度比较

Comparison of mutant prevention concentrations of fluoroquinolones against methicillin-resistant and susceptible Staphylococcus aureus isolated from animal

目的比较4种氟喹诺酮类药物对动物源性MRSA和MSSA的耐药突变体的选择能力。方法采用琼脂平板稀释法分别测定环丙沙星、左氧沙星、加替沙星和吉米沙星对MRSA和MSSA的MIC值和MPC值,并计算MIC90和MPC90。结果 4种氟喹诺酮药物对85株动物源性MSSA的MPC90值分别为4mg/L、2mg/L、0.5mg/L、0.5mg/L,加替沙星的MPC90/MIC90比值最小;对21株动物源性MRSA的MPC90值分别为128mg/L、64mg/L、16mg/L、8mg/L,吉米沙星的MPC90/MIC90比值最小。结论对动物源性MSSA,加替沙星防耐药突变能力优于其它,加替沙星和吉米沙星单药能有效限制耐药突变株的选择,而左氧沙星和环丙沙星则易选择耐药菌株。对动物源性MRSA,4种药物单药给药均不能有效限制耐药突变株的选择。

In order to compare the selection capacity on resistant mutant strains of 4 kinds of fluoroquinolones against methicillin-susceptible （MSSA） and methicillin-resistant （MRSA） S. aureus isolated from animal, the minimum inhibitory con- centration （MIC） and mutant prevention concentration （MPC） of ciprofloxacin, levofloxacin, gatifloxacin, and gemifloxacin for MSSA and MRSA were determined by agar plate dilution methods. The results showed that for 85 MSSA strains, the rank or- der of potency based on MPC90 values were ciprofloxacin （4 mg/L） 〉 levofloxacin （2 mg/L） 〉 gatifloxacin （0.5 mg/L） gemifloxacin （0.5 mg/L）. The selective index （MPC90/MIC90） of gatifloxacin was minimal. For 21 MRSA strains, the MPC90 of ciprofloxacin, levofloxacin, gatifloxacin and gemifloxacin were 128 mg/L, 64 rag/L, 16 mg/L and 8 mg/L respectively and the selective index of gemifloxacin was minimal. The ability of gatifloxacin for restricting the selection of MSSA resistant mu- tants was stronger than that of other fluoroquinolones. Gatifloxacin and gemifloxacin may restrict the selective enrichment of resistant mutants among MSSA whenever they are administered as mono-therapy. But for MRSA strains, four fluoroquinolones will select resistant mutants whenever they are administered as mono-therapy.