危重患者抗生素应用过程中致病菌快速变化的探讨

目的 探讨危重患者抗生素目标治疗7 d内致病菌种类和比例变化的特点.方法 对已明确致病菌并根据细菌学检验使用抗生素的100例医院获得性肺炎(HAP)患者,观察不同时间内痰标本中检测出的致病菌种类和比例的变化,并分析其与年龄、用药时间、住院时间等因素的关系.结果 共分离出295株致病菌,其中以革兰阴性(Gˉ)菌为主,占菌株数的62.4%(184/295).排在前3位的致病菌分别为铜绿假单胞菌22.4%(66/295)、耐甲氧西林金黄色葡萄球菌/耐甲氧西林表皮葡萄球菌(MRSA/MRSE)20.7%(61/295)、不动杆菌属10.5%(31/295),占菌株数的53.6%.根据细菌培养结果选用敏感抗生素1种及以上,结果发现,致病菌比例发生变化160株,种类发生变化126株;其中随抗生素使用时阃延长,致病菌比例变化逐渐下降,3～5 d致病菌比例变化较6～7 d明显,分别为72.7%、62.5%、60.0%(P＜0.01),说明治疗效果确切;而致病菌种类变化则随时间延长逐渐增多,6～7 d较3～5 d变化为甚,分别为66.0%、77.1%(P＜0.01),表现为新的非敏感菌种出现.随着抗生素应用种类的增加,致病菌种类变化呈逐渐增加的趋势.抗Gˉ菌时常出现的新菌种为白色念珠菌、MRSA;抗G+菌时常出现的新菌种为白色念珠菌、铜绿假单胞菌、阴沟肠杆菌.致病菌的变化与年龄和住院时间有关,年龄越大,住院时间越长,致病菌的种类变化越显著.结论 抗生素目标治疗7 d内即可出现新的非敏感致病菌,且抗生素使用时间越长,种类越多,致病菌的种类变化越明显;患者年龄越大,住院时间越长,致病菌的种类变化也越明显.致病菌种类的变化中白色念珠菌出现几率较高.动态监测致病菌的变化,及时调整并合理使用抗生素,对进一步认识及攻克难治性感染具有重要意义.

The vicissitude of pathogenic bacteria isolated from critically ill patients in an intensive care unit during a period of using antibiotics

Objective To observe the changing spectrum of the pathogenic bacteria during seven-day antibiotics targeted therapy in an intensive care unit(ICU).Methods In a group of 100 patients of hospital-acquired pneumonia(HAP)with identified pathogenic bacteria undergoing antibiotic treatment according to susceptibility test,the changes in the species of the pathogens and their ratio in their sputum specimens were studied,and the relationship were analyzed the characteristic between the changes and the age,the time of medication and the length of stay.Results Among all the bacterial isolates(n=295)in ICU,the percentage of Gram-negative bacillus was 62.4%(184/295).The prevalent causative microorganisms isolated were Pseudomonas aeruginosa 22.4%(66/295),MRSA/MRSE 20.7%(61/295)and Acinetobacter spp.10.5% (31/295).When one or more than one potent antibiotic in accord with the result of sensitivity test,change in ratio of pathogens occurred in 160,and change in species in 126.When the use of antibiotics was prolonged,the change in the former became less often.The change in ratio was less in 3-5 days than that of 6-7 days,the ratio was 72.7%,62.5%,60.O%(P<0.01)respectively on the 3rd day,the 4th day and the 5th day,showing that susceptible pathogenic bacteria became less gradually,indicating that the treatment was effective,However,the change in species of pathogenic bacteria began more obvious,and it was more predominant on the 6th day and the 7th day,which was 66.0%,77.1%(P<0.01)respectively,showing emergence of new non-susceptible pathogenic bacteria.With increase in the use of different antibiotics,the species of pathogenic bacteria showed to increase an increasing tendency of change.When Gram-negative bacillus infection was treated,antibiotic resistant bacteria such as Candida albicans and MRSA usually appeared.But when Gram.positive bacillus infections were treated,Candida albicans,Pseudomonas aeruginosa and Enterobacter cloacae readily appeared.There was relationship between the change in pathogenic bacteria and age,and the length of stay of the patients.The more older in age and the longer the length of stay,the change in pathogenic bacteria was more predominant.Conclusion New antibiotic resistant pathogenic bacteria appeares after seven-day antibiotic-targeted therapy in ICU.The change of species of pathogenic bacteria is related to the duration and type of using antibiotic,and also the age and length of stay.The longer time of use and the more different types of antibiotic used,the older in age and the longer in length of stay,the change in species of pathogenic bacteria is more predominant.Monitoring the dynamic change of pathogenic bacteria,adjusting the antibiotic promptly and rational use of antibiotics are very important to decrease the change in species and antibiotic resistance of the bacteria.