The antibiotic susceptibility and extended spectrum .BETA.-lactamase genotype of clinical Klebsiella pneumoniae

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 2007[18.8% (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. Key words: Klebsiella pneumoniae; Drug resistance, bacterial; Microbial sensitivity tests; beta-Lactamases; Genotype