摘要目的 研究烧伤病房分离的甲氧西林耐药金黄色葡萄球菌(MRSA)的葡萄球菌盒式染色体mec(SCCmec)基因分型及耐药现状. 方法 2012年9月-2013年9月,从笔者单位烧伤整形科ICU及普通病房送检的患者创面分泌物、血液及痰液标本r中,检出非重复金黄色葡萄球菌179株(ICU来源68株、普通病房来源111株).采月头孢西丁K-B纸片扩散法检测金黄色葡萄球菌MRSA表型,对ICU和普通病房中MRSA检出率进行比较.采用PCR法对MRSA进行SCCmec.分型,经检测甲氧西林耐药决定子mecA基因对前述MRSA鉴定结果进行验证 . 采用用 K-B纸片扩散法检测MRSA与甲氧西林敏感金黄色葡萄球菌(MSSA)对23种临床常用抗菌药物的耐药情况 除去MRSA对其耐药率为100.0％或0的抗菌药物,将SCCmecⅢ型MRSA与非SCCmecⅢ型MRSA 对剩余抗菌药物的耐药率进行比较对数据行Pearsonx2检验或校正x2检验. 结果 179株金黄色葡萄球菌中148株鉴定为MRSA占82.7％,其中ICU来源62株、普通病房来源86株;其余31株为MSSA占 17.3％.ICU中 MRSA在该病区内检出金黄色葡萄球菌中所占百分比为91.2％(62/68),显著高于普通病房中的77.5％(86/111),x2=5.526,P=0.019. PCR检测显示148株MRSA均携带mecA基因,其中106株为SCCmecⅢ型阳性占71.6％;ICU与普通病房中 SCCmecⅢ型MRSA占各自病区内检出MRSA的百分比分别为72.6％ (45/62)和70.9％ (61/86),差异无统计学意义(x2=0.048,P=0.826).148株MRSA对青霉素及头孢类抗生素共8种抗菌药物100.0％耐药,对万古霉素、替考拉宁、利奈唑胺、替加环素、呋喃妥因及奎奴普丁/达隔普汀的耐药率均为0除2种菌对其耐药率为0的6种抗菌药物外,MRSA对剩余17种抗菌药物的耐药率均显著高于MSSA(x2值为4.091 ～138.546,P＜0.05或P＜0.01) 106株SCCmecⅢ型MRSA对左氧氟沙星、环丙沙星、利福平、四环素、红霉素、林可霉素、庆大霉素、克林霉素的耐药率分别为56.6％(60/106)、85.8％ (91/106)、89.6％ (95/106) 、86.8％(92/106)、84.9％ (90/106)、78.3％(83/106)、92.5％ (98/106)、74.5％ (79/106),均显著高于42株非SCCmecⅢ型MRSA的33.3％ (14/42)、61.9％(26/42) 、71.4％ (30/42)、66.7％ (28/42) 、69.0％(29/42)、57.1％(24/42)、71.4％(30/42)、52.4％ (22/42),x2值为4.801 ～11.377,P＜0.05或P＜0.01. 结论 笔者单位烧伤病房的MRSA检出率高且耐药现状十分严峻,流行情况以SCCmec.Ⅲ型为主,未见对糖肽类抗生素耐药情况.

abstractsObjective To investigate the genotype of staphylococcal chromosomal cassette mec (SCCmec) in methicillin-resistant Staphylococcus aureus (MRSA) isolated from burn wards and its current status of drug resistance.Methods One hundred and seventy-nine strains of Staphylococcus aureus were isolated from wound excretion,blood,and sputum samples of patients that were admitted to ICU or public wards of our Department of Burns and Plastic Surgery from September 2012 to September 2013.Among them,68 strains were from ICU and 111 strains from public wards.The MRSA phenotype of Staphylococcus aureus was detected with cefoxitin K-B disk diffusion method,and the isolation rates of MRSA in ICU and public wards were compared.Genotyping of SCCmec was performed by PCR in strains of MRSA.In the meantime,the identification result of MRSA by K-B method was verified through detecting methicillin-resistant determinant mecA.The antimicrobial resistance of MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) to 23 kinds of commonly used antibiotics in clinic were detected by K-B disk diffusion method.Except for the antibiotics to which the resistant rates of MRSA were 100.0％ or 0,the resistant rates of SCCmec Ⅲ MRSA and non-SCCmecⅢ MRSA to the rest of antibiotics were compared.Data were processed with Pearson chi-square test or corrected chi-square test.Results One hundred and forty-eight strains out of the 179 Staphylococcus aureus were identified as MRSA (accounting for 82.7％),among which 62 were originated from ICU and 86 from public wards.The rest 31 strains of Staphylococcus aureus were MSSA,accounting for 17.3％.The percentage of MRSA in the isolated Staphylococcus aureus was 91.2％ (62/68)in ICU,which was significantly higher than that in the public wards [77.5％ (86/111),x2 =5.526,P =0.019].PCR detection showed that the 148 strains of MRSA harbored the mecA gene,out of which 106 strains were SCCmec Ⅲ positive,accounting for 71.6％.The percentages of SCCmec Ⅲ type MRSA in MRSA isolated from ICU and public wards were respectively 72.6％ (45/62) and 70.9％ (61/86),showing no statistically significant difference(x2 =0.048,P =0.826).The 148 strains of MRSA were 100.0％ resistant to a total of 8 kinds of antibiotics including penicillin and cephalosporins,but it was 0 for vancomycin,teicoplanin,linezolid,tigecycline,nitrofurantoin,and quinupristin/dalfopristin.Except for the 6 kinds of antibiotics to which the resistant rates of MRSA and MSSA were 0,resistant rates of MRSA to the remaining 17 kinds of antibiotics were significantly higher than those of MSSA (with x2 values from 4.091 to 138.546,P ＜ 0.05 or P ＜ 0.01).Resistant rates of the 106 strains of SCCmec Ⅲ type MRSA to levofloxacin,ciprofloxacin,rifampicin,tetracycline,erythrocin,lincomycin,gentamicin,clindamycin were respectively 56.6％ (60/106),85.8％ (91/106),89.6％ (95/106),86.8％ (92/106),84.9％ (90/106),78.3％ (83/106),92.5％ (98/106),74.5％ (79/106),and they were significantly higher than those of the 42 strains of non-SCCmecⅢ type MRSA [33.3％ (14/42),61.9％ (26/42),71.4％ (30/42),66.7 ％ (28/42),69.0％ (29/42),57.1％ (24/42),71.4％ (30/42),52.4％ (22/42),with x2 values from 4.801 to 11.377,P ＜ 0.05 or P ＜ 0.01].Conclusions Isolation rate of MRSA from burn wards in our hospital is high,and drug resistance status of this strain against antibiotics is very serious.SCCmec Ⅲ is the major genotype of the isolated MRSA,but no strains resistant to the glycopeptide antibiotics are found.