临床表葡菌耐药性和氟喹诺酮类药物外排检测研究

Detection of resistance and fluoroquinolone-resistant efflux pump in Staphylococcus epidermidis

分离鉴定临床表葡菌126株,通过Kirby-Bauer法和平皿二倍稀释法测定了126株临床分离表皮葡萄球菌对13种抗菌药物(甲氧西林、卡那霉素、庆大霉素、氨苄西林、四环素、红霉素、克林霉素、磺胺甲口恶唑/甲氧苄啶、利福平、头孢曲松、头孢噻肟、头孢唑林、万古霉素)的耐药水平及78株表葡菌对13种抗菌药物的耐药谱。126株表葡菌中甲氧西林耐药菌(MRSE)为79株,占62.7%。万古霉素对MRSE和MSSE的作用最好,抑菌率均为100%,利福平对MRSE的抑菌作用也较强,抑菌率为83.5%,其次是卡那霉素、四环素和磺胺甲口恶唑/甲氧苄啶。采用平皿二倍稀释法测定78株表葡菌(从126株菌随意挑选)对4种氟喹诺酮类药物(诺氟沙星、氧氟沙星、环丙沙星和司帕沙星)的耐药水平及交叉耐药性。78株表葡菌中,对环丙沙星耐药25株(32.05%);对诺氟沙星耐药34株(43.59%);对氧氟沙星耐药22株(28.21%);对司帕沙星耐药16株(20.51%)。且菌株对此4种药物存在高度交叉耐药性;16株表葡菌在加入利舍平后MIC变小,说明外排泵介导的氟喹诺酮耐药机制普遍存在于临床分离的表葡菌中。但菌株SE7、SE9、SE68的MIC在加入利舍平后增大。说明这些菌株中除主动外排耐药机制外,还存在着其它耐药机制。

One hundred and twenty-six clinical isolates of Staphylococcu epidermidis were identified and their resistance was determined by Kirby-Bauer method and the antimicrobial susceptibility tests against 13 antibiotics were also performed. There are 79 MRSE (62.7%) among them. Vancomycin has a good antibacterial activity to MRSE and MSSE, then rifampicin, kanamycin, tetracycline and trimoxazole. In 78 isolates randomly selected from S.epidermidis, there are 25 ciprofloxacin-resistant strains, 34 norfloxacin-resistant strains, 22 ofloxacin-resistant strains and 16 sparfloxacin-resistant strains. In these strains, there exists high cross-resistance to four drugs. The MIC of 16 S.epidermidis decreased after adding of reserpine. It was considered that efflux pump-mediated resistant mechanism exists in clinical isolates of S.epidermidis. On the contrary, MIC of SE7, SE9 and SE68 increased after adding of reserpine. It was suggested that there are another resistant mechanism besides efflux pump-mediated resistant mechanism.