Li Xiao-fang, Fan Xin-jian, Guo Xiao-Jing, Feng Peng, Lü Xiao-ju, Gao Yan-Yu, Xiong Ya-Li, Yu Ru-Jia, Ding Xia
Department of Infectious Diseases, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.
Sichuan Da Xue Xue Bao Yi Xue Ban. 2006 May;37(3):365-8.
To inquire into the mechanism of drug resistance in Staphylococcus aureus.
A total of 198 strains of Staphylococcus aureus were isolated from the samples sent to the Clinical Laboratory of Microbiology,West China Hospital. The resistance of Staphylococcus aureus to Methicillin was assayed with agar dilution. Staphylococcus aureus mecA gene was measured by PCR assay and beta-lactamase was detected by Nitrocephin.
The rate of resistance to methicillin was 64.65% in 198 strains of Staphylococcus aureus; 118 strains of methicillin-resistant staphylococcus aureus(MRSA) were found to have high level resistance in 128 MRSA;10 strains of MRSA were found to have low level resistance; 41(58.57%) strains of methicillin-sensitive Staphylococcus aureus (MSSA) expressed beta-lactamase; 2 Staphylococcus aureus had mecA among them; 67 Staphylococcus aureus expressed beta-lactamase in high level resistance, 63(53.39%)Staphylococcus aureus expressed beta-lactamase in high level resistance, among them, 5 Staphylococcus aureus had mecA; 40.00% MRSA expressed beta-lactamase in low level resistance, 55 MRSA did not express beta-lactamase in high level resistance, which had all mecA; 9 Staphylococcus aureus did not express beta-lactamase in low level resistance, among them, 5 Staphylococcus aureus had mecA. The difference in expression of beta-lactamase was statistically significant between MSSA and MRSA; MRSA(53.39%) was lower than MSSA (58.57%); the other differences were not significant. The difference in having mecA was statistically significant between MRSA(having high resistant level and no expression of beta-lactamase) and the others; MRSA had higher mecA than did the others.
The resistance in Staphylococcus aureus mainly involved two mechanisms: the expression of beta-lactamase and the expression of mecA.
探讨金黄色葡萄球菌耐药机制。
从四川大学华西医院临床微生物实验室送检标本中分离出198株金黄色葡萄球菌。采用琼脂稀释法检测金黄色葡萄球菌对甲氧西林的耐药性，用聚合酶链反应（PCR）法检测mecA基因，用头孢硝噻吩检测β-内酰胺酶。
198株金黄色葡萄球菌中对甲氧西林耐药率为64.65%；118株耐甲氧西林金黄色葡萄球菌（MRSA）中，128株呈高水平耐药，10株呈低水平耐药；41株（58.57%）甲氧西林敏感金黄色葡萄球菌（MSSA）表达β-内酰胺酶，其中2株含mecA基因；67株MRSA呈高水平耐药，63株（53.39%）呈高水平耐药，其中5株含mecA基因；40.00%的MRSA呈低水平耐药表达β-内酰胺酶，55株MRSA呈高水平耐药不表达β-内酰胺酶，均含mecA基因；9株MRSA呈低水平耐药不表达β-内酰胺酶，其中5株含mecA基因。MSSA与MRSA的β-内酰胺酶表达差异有统计学意义；MRSA（53.39%）低于MSSA（58.57%）；其他差异无统计学意义。MRSA（高水平耐药且不表达β-内酰胺酶）与其他菌株含mecA基因差异有统计学意义；MRSA的mecA基因携带率高于其他菌株。
金黄色葡萄球菌耐药主要涉及β-内酰胺酶表达和mecA基因表达两种机制。
