头孢哌酮-舒巴坦药敏纸片中舒巴坦量对药敏结果的影响

目的 探讨头孢哌酮-舒巴坦药敏纸片中舒巴坦量对药敏结果 的影响.方法 用琼脂稀释法检测头孢哌酮、头孢哌酮-舒巴坦(2:1)和头孢哌酮-舒巴坦(1:1)3组药对临床分离的534株革兰阴性杆菌的MIC值;用纸片扩散法检测头孢哌酮、头孢哌酮-舒巴坦75/30μg和75/75μg 3种纸片对此534株菌的抑菌环直径;分析MIC结果 之间、纸片扩散法之间,以及2种药敏方法 之间的结果 是否有差异.结果 经琼脂稀释法检测头孢哌酮、头孢哌酮-舒巴坦(2:1)和(1:1)MIC_(50)分别为:32、16、16μg/ml,MIC_(90)分别为≥256,128,64μg/ml,Wilcoxon秩和检验两种药量配比MIC结果 无统计学差异(Z=-0.248,P=0.804);头孢哌酮-舒巴坦75/30μg药敏纸片(75/30纸片)检测的敏感率(S%)、耐药率(R%)和中介率(I%)分别为55.3%、24.5%和20.2%,与琼脂稀释法结果 相似.头孢哌酮-舒巴坦75/75μg(75/75纸片)敏感率、耐药率和中介率分别为72.5%、12.4%和15.1%,比75/30纸片检测的总敏感率高17.2%,对75/30纸片及75/75纸片测所有菌株的2组抑菌环直径进行配对t检验(t=21.613,P＜0.01),但这种差异只来自于CISI规定检测出的产ESBL菌株、鲍曼不动杆菌和未经ESBL检测的其他肠杆菌科菌株;而对铜绿假单胞菌、嗜麦芽窄食单胞菌和ESBL阴性菌株的敏感率或耐药率差异无统计学意义.结论 头孢哌酮-舒巴坦(2:1)和(1:1)琼脂稀释法药敏结果 及75/30μg纸片法药敏结果 无差异.当使用75/75μg药敏纸片报告产ESBL菌株、鲍曼不动杆菌和其他肠杆菌科菌株的药敏结果 时,应注明舒巴坦的含量.

Influence of sulbactam content on susceptibility testing results of cefoperazone/sulbactam combination disks

Objective To study the discrepancy influence of the sulbactam content on susceptibility testing results of cefoperazone/sulbactam combination disks.Methods Agar dilution method was used to determine MICs of cefoperazone,cefoperazone/sulbactam(2:1 and 1:1),and disk diffusion was used to detect the zone diameters of cefoperazone,cefoperazone/sulbactam(75/30 and 75/75μg/disk)disks against 534 clinical gram-negative isolates.The discrepancy within the results of MICs,zore diameters,the method of agar dilution and disk diffusion was analyzed.Results By standard agar dilution method,MIC_(50) of cefoperazone,cefoperazone/sulbactam(2:1 and 1:1)were 32,16,16μg/ml,and MIC_(90) of those were ≥256.128,64 μg/ml respectively.No statistic discrepancy was found for MICs between the ratios of 2:1 and 1:1 combination by Wilcoxon ranks test(Z=-0.248,P=0.804).Susceptibility rate,resistance rate,and intermediate rate with 75/30μg disk were 55.3%,24.5%and 20.2%respectively,which were similar to those determined by agar dilution method.Susceptibility rate,resistance rate,and intermediate rate(I%)with 75/75μg disk were 72.5%,12.4% and 15.1% respectively,compared with the susceptibility rate from 75/30μg disk was 17.2% higher.Statistic discrepancy were tested by paired t-test (t=21.613,P＜0.01)with two groups of whole strains' zone diameters from 75/30μg and 75/75μg disks,and resulting in the difference of susceptibility or resistance rates for ESBL-producing strains,Acinetobacter bauamnnii and Enterobacteriaceae without ESBL tested isolates.On the contrary,for Pseudomonas aeruginosa,Stenotrophomonas maltophilia and ESBL negative isolates,the zone diameters discrepancy was not statistically significant between the results from 75/30μg and 75/75μg disks.Conclusions There is no statistic discrepancy between the susceptibility results from cefoperazone/sulbactam(2:1 or 1:1 ratios)in dilution method and in diffusion method with 75/30μg disk.When the 75/75μg disk is used to be tested for ESBL-producing strains,Acinetobacter bauamnnii and other Enterobacteriaceae,the results should be shown with sulbactam content.