近4年产超广谱β-内酰胺酶肺炎克雷伯菌基因型分布及耐药性变化

Genotype Profiles and Antibiotic Resistance of ESBLs-producing Klebsiella pneumoniae Isolates during Last Four Years

目的了解我院近4年产超广谱β-内酰胺酶(ESBLs)肺炎克雷伯菌的基因型分布及耐药性性变化. 方法采用美国临床实验室标准化委员会(NCCLS)推荐的表型确证试验,筛选出我院2000年6月～2003年8月产ESBLs肺炎克雷伯菌64株;应用PCR及DNA测序方法检测所有产酶株的TEM、SHV及CTX-M基因.应用琼脂稀释法测定11种抗菌药物对所有产酶株最低抑菌浓度(MIC). 结果 64株肺炎克雷伯菌产生的ESBLs 以SHV-12和CTX-M-14为主要基因型,在产酶株中的检出率分别51.6%和46.9%,2000年只检出SHV-12基因,2001年共检出9种基因型, 2002年共检出10种基因型, 2003年共检出8种基因型;2000年未发现携带多个基因的菌株,2001年多基因携带率达50%, 2002年多基因携带率达51.6%, 2003年多基因携带率达63.6%,2001～2003年3年间多基因携带率差异无显著性;2000年的6株菌均对头孢他啶和氨曲南的耐药,对氨苄西林/舒巴坦也有较高耐药性,对其他药物很敏感,2001～2003年间的产ESBLs肺炎克雷伯菌除对亚胺培南100%敏感外,对其余10种抗菌药物出现不同程度的耐药. 结论我院肺炎克雷伯菌临床分离株中的ESBLs基因型主要为SHV-12和CTX-M-14,且携带多种β-内酰胺基因产酶株检出率高,所有产酶株均对亚胺培南敏感.

OBJECTIVE To understand the profiles of genotype and antibiotic resistance of E5BLs-producing Klebsiella pneumoniae isolates from our hospital during the last four years. METHODS Sixty four ESBLs- producing K. pneumoniae isolates were detected by phenotype confirmatory test according to NCCLS standard from isolates between J un 2000 and Aug 2003. TEM,SHV and CTX-M genes in these ESBLs-producing isolate were detected by PCR and DNA sequencing. Minimal inhibitory concentrations （MIC） for 11 antibiotics against the isolates were determined by the agar dilution method. RESULTS （1） SHV-12 type and CTX-M-14 type were common ESBLs that produced by 64 K. pneumoniae isolates. Of all these isolates,51.6% were detected harboring blaSHV-12,46.9% were detected harboring CTX-M-14. （2）In 2000, all isolates were found harboring only blaSHV-12 gene. Among the isolates in 2001,2002 and 2003, 50%, 51.6% and 63.6%, respectively were found, harboring more than one β-1actamase genes we analyzed. （3） Six isolates in the year of 2000 were all resistant to ceftazidime and aztreonam,and had high resistance rate to ampicillin/sulbactam, but they were almost susceptible to the rest of the antibiotics. Isolates between 2001 and 2003 were all susceptible to imipenem, but they showed various resistance to other antibiotics. CONCLUSIONS SHV-12 and CTX-M-14 are major genotypes of ESBLs produced strains by clinical isolates in our hospital. ESBLs-producing K. pneumoniae which harbored more than one β-lactamase genes are very commom. All these isolates are susceptible to imipenem.