肺炎克雷伯菌药敏分析及其超广谱β内酰胺酶基因分型研究

目的 对北京大学人民医院分离的肺炎克雷伯菌进行药敏分析及ESBL型别测定,为控制院内肺炎克雷伯菌感染提供依据.方法 收集北京大学人民医院2001-2007年分离的1 205株肺炎克雷伯菌,采用Vitek-2全自动药敏鉴定分析仪对菌株进行鉴定及药敏试验,采用WHONET 5.3软件进行药敏结果分析,PCR法检测ESBL基因型别,比较分析各种药物敏感率和基因型比率特征和差异.结果 2001-2007年肺炎克雷伯菌中产ESBL比例逐年增加:2001年为15.8% (40/253),2002年为20.9% (53/253),2003年为32.8% (42/128),2004年为32.8% (45/137),2005年为36.6% (60/164),2006年为45.3% (68/150),2007年为45.6% (73/160).ESBL阳性菌株中SHV基因检出比例最大,2007年为83.6%(61/73).ESBL阳性菌株中CTX-M基因检出率逐年增加,2007年为54.8%(40/73).携带单一SHV基因菌株与同时携带SHV、CTX-M基因菌株对头孢他啶、头孢曲松及头孢噻肟的耐药率差异有统计学意义(χ2值分别为20.26、32.03、29.65,P均＜0.05);携带单一SHV基因菌株与同时携带SHV、TEM基因菌株对头孢他啶、头孢曲松及头孢噻肟的耐药率差异有统计学意义 (χ2值分别为7.01、9.93、11.01,P均＜0.05);携带单一SHV基因菌株与同时携带SHV、OXA基因菌株对头孢他啶、头孢曲松及头孢噻肟的耐药率有统计学差异 (χ2值分别为14.11、17.58、11.54,P均＜0.05);携带CTX-M基因菌株与同时携带SHV、CTX-M基因菌株对头孢他啶耐药率差异有统计学意义(χ2=23.61,P＜0.05);携带TEM基因菌株与同时携带SHV、TEM基因菌株对头孢他啶耐药率差异有统计学意义(P=0.01).结论 肺炎克雷伯菌产ESBL逐年增加,以SHV型为主,携带CTX-M型ESBL基因菌株逐年增多.

Abstract：

Objective To analyze the antibiotic susceptibility, ESBL genotype of clinical Klebsiella pneumoniae strains isolated from People′s hospital and facilitate the control of resistance spread. Methods Identification and antibiotic susceptibility tests of 1 205 strains from 2001 to 2007 were done by VITEK-2 system.The antibiotic susceptibility results were analyzed by whonet5.3.The ESBL gene was detected by PCR and the Chi-square test was used for statistical analysis.Results The rate of ESBL-producing strains in klebsiella pneumoniae has increased from 2001 to 200718.8% (40/213) in 2001, 20.9% (53/253) in 2002, 32.8% (42/128) in 2003, 33.6% (45/137) in 2004, 36.6% (60/164) in 2005, 45.3% (68/150) in 2006 and 45.6% (73/160) in 2007].The SHV gene was the most dominant in ESBL genotypes.There were 83.3% (50/60) ESBL strains in 2005 with SHV gene, 82.3%(56/68) in 2006 and 83.6%(61/73) in 2007.The rated of strains with CTX-M gene were increasing.There were 26.7%(16/60) ESBL strains with CTX-M gene in 2005, 36.7%(25/68) in 2006 and 54.8%(40/73) in 2007.The isolates with more than one type of ESBL gene were increasing.There were 45%(27/60) ESBL strains in 2005 with two types of ESBL gene, and no one had more than two types of ESBL gene in that year.There were 47.9%(35/73) ESBL strains in 2007 with two types of ESBL gene.In 2007 there were 9.6%(7/73) and 2.7%(2/73) ESBL strains with three types and four types of ESBL gene respectively.There was a statistical difference between the antibiotic resistance rates of cefotaxime, ceftriaxone and ceftazidime in SHV-gene-phore strains (χ2=13.22, P＜0.01).The strains with SHV gene were more resistant to cefotaxime than ceftriaxone and ceftazidime.There also was a statistical difference of the antibiotic resistance rate of cefotaxime, ceftriaxone and ceftazidime between strains with TEM gene (χ2=9.91, P＜0.01) and CTX-M gene (χ2=34.84, P＜0.01) respectively.None of the strains with CTX-M gene was sensitive to cefotaxime, and they were more resistant to ceftriaxone than ceftazidime.The strains with TEM gene were more resistant to cefotaxime than ceftriaxone and ceftazidime.There were statistical differences of the antibiotic resistance rate to cefotaxime (χ2=29.65, P＜0.01), ceftriaxone (χ2=20.26, P＜0.01) and ceftazidime (χ2=20.26, P＜0.01) between the strains with SHV gene only and strains with SHV and CTX-M gene concurrently.There were also statistical differences of the antibiotic resistance rates to cefotaxime (χ2=11.01, P＜0.01), ceftriaxone (χ2=9.93, P＜0.01) and ceftazidime (χ2=7.01, P＜0.01) between the strains with SHV gene only and strains with SHV and TEM gene concurrently.The antibiotic resistance rates to cefotaxime (χ2=11.54, P＜0.01), ceftriaxone (χ2=17.58, P＜0.01) and ceftazidime (χ2=14.11, P＜0.01) were statistically different between the strains with SHV gene only and strains with SHV and OXA gene concurrently.The antibiotic resistance rates to ceftazidime (χ2=23.61, P＜0.01) were statistically different between the strains with CTX-M gene only and strains with SHV and CTX-M gene concurrently. There was no statistical difference in antibiotic resistance rates to cefotaxime (χ2=3.55, P＜0.01) and ceftriaxone (χ2=3.35, P＜0.01) between the strains with CTX-M gene only and strains with SHV and CTX-M gene concurrently. The antibiotic resistance rates to ceftazidime (P=0.01) were statistically different between the strains with only TEM gene and strains with SHV and TEM gene concurrently, and there was no statistical difference of the antibiotic resistance rates to cefotaxime (P=0.29) and ceftriaxone (P=0.26) between the strains with TEM gene only and strains with SHV and TEM gene concurrently. ConclusionsThe producing rate of ESBL is increasing year after year and the SHV type of ESBL is the dominant one.Strains with more than one type of ESBL gene are increasing.The antibiotic resistance rates to cefotaxime, ceftriaxone and ceftazidime are statistically different between strains with same ESBL genotype.