青霉素对金黄色葡萄球菌耐药性及β-内酰胺酶活性的影响

Penicillin Resistance in Staphylococcus aureus and β-Lactamase Activity

目的观察青霉素对金黄色葡萄球菌耐药性及β-内酰胺酶活性的影响。方法将金黄色葡萄球菌对青霉素的敏感株及耐药株分别接种于青霉素培养基内,培养不同时间取培养物检测菌落数、青霉素残留活性及β-内酰胺酶活性。结果在64μg/ml青霉素培养基中培养24h,敏感株菌落数逐步减少;耐药菌在前6h菌落数明显减少,但随后显著增加;接种了敏感株的培养基中的青霉素活性维持稳定,接种了耐药株的培养基中的青霉素活性逐步降低;耐药菌的β-内酰胺酶活性随培养时间延长而明显增高。结论青霉素对生长繁殖早期阶段的金黄色葡萄球菌可以产生明显的抑制或杀灭作用,青霉素可诱导耐药菌株产生更多的β-内酰胺酶,从而导致细菌耐药性增强。

OBJECTIVE To study penicillin resistance in Staphylococcus aureus and the activity of β-lactamase. METHODS The strains of S. aureus both sensitive and resistant to penicillin were inoculated into the media with penicillin and then incubated in 37 ℃. The number of the bacteria and the activities of β-lactamase, were determined respectively at varying times. RESULTS In the media with 64 μg/ml penicillin, the number of the sensitive strain decreased gradually in 24 h of culturing. The number of the resistant strains decreased at first 6 h and then the number increased in subsequent 24 h. The activity of penicillin did not be changed in the media with the sensitive strain. The activitiy of penicillin was decreased obviously with the resistant stains. In the media without penicillin, the β-lactamase activities of the resistant stains were stable until 24 h of culturing, while the β- lactamase activities were increased gradually in the media with penicillin. CONCLUSIONS The growth of early stage of S. aureus can be inhibited obviously by penicillin. β-Lactamase would be induced largely in resistant S. aureus.