BACKGROUND & AIMS:
:We assessed the prevalence and phenotypic characteristics of extended-spectrum beta-lactamase (ESBL) producers among cefuroxime-resistant (CXM-R) (MIC > or = 32 micro g/ml) members of the family Enterobacteriaceae in our institution. The 438 CXM-R clinical isolates obtained from nonurine sources among inpatients were screened. ESBL production was confirmed by disk diffusion assay using cefpodoxime (CPD), cefotaxime (CTX), and ceftazidime (CTZ) with and without clavulanate (CLAV). A difference of > or =5 mm in the size of the zone of inhibition in the presence of CLAV for at least one of the agents was considered representative of the ESBL phenotype: 186 isolates (42.5%) were confirmed as ESBL producers. The isolates tested and the rates of ESBL producers were as follows: Klebsiella spp. (n = 81), 79%; Proteus spp. (n = 58), 62%; Escherichia coli (n = 64), 53%; Enterobacter spp. (n = 69), 42%; Serratia spp. (n = 70), 14%; Citrobacter spp. (n = 25), 24%; Providencia spp. (n = 21), 24%; Morganella spp. (n = 41), 5%; and Kluyvera (n = 3), 0%. The overall sensitivity of isolated ESBL confirmatory tests was 79% for CPD-CLAV, 66% for CTZ-CLAV, and 91% for CTX-CLAV. Sensitivities of CTZ-CLAV confirmatory tests for Klebsiella spp., Proteus spp., E. coli, and Enterobacter spp. were 84, 22, 76, and 62%, respectively, and those for CTX-CLAV were 95, 97, 94, and 83%, respectively. They were 90% for CPD-CLAV and CTZ-CLAV, 95% for CPD-CLAV and CTX-CLAV, and 100% for CTZ-CLAV and CTX-CLAV. ESBL production was highly prevalent among Enterobacteriaceae. Using resistance to CXM as an ESBL screening criterion is a suitable option in high-incidence areas where Klebsiella spp. are not the dominant ESBL producers. This screening criterion may simplify the screening test and improve its sensitivity, although at the price of testing more isolates. The CTX-CLAV combination confirmed ESBL producers better than the CTZ-CLAV combination, with sensitivity varying between species. Combined CTZ-CLAV and CTX-CLAV testing detected all these strains; CPD-CLAV provided no additional benefit.
背景与目标:
:我们评估了我院肠杆菌科的耐头孢呋辛(CXM-R)(MIC>或= 32 micro g / ml)成员中广谱β-内酰胺酶(ESBL)生产者的患病率和表型特征。筛选了从住院患者中从非尿液来源获得的438种CXM-R临床分离株。通过使用头孢泊肟(CPD),头孢噻肟(CTX)和头孢他啶(CTZ)进行克拉维酸盐(CLAV)和不进行克拉维酸盐(CLAV)的磁盘扩散测定,证实了ESBL的产生。对于至少一种试剂,在存在CLAV的情况下,抑制区大小的差异≥5mm被认为是ESBL表型的代表:已确认186种分离株(42.5%)是ESBL的产生者。测试的分离物和ESBL产生者的比率如下:克雷伯菌属(Klebsiella spp)。 (n = 81),79%;变形杆菌属(n = 58),62%;大肠杆菌(n = 64),占53%;肠杆菌属。 (n = 69),42%;沙雷氏菌(n = 70),14%;柠檬杆菌属。 (n = 25),24%; Providencia spp。 (n = 21),24%; Morganella spp。 (n = 41),5%;和Kluyvera(n = 3),0%。隔离的ESBL确证测试的总体敏感性对于CPD-CLAV为79%,对于CTZ-CLAV为66%,对于CTX-CLAV为91%。 CTZ-CLAV确证试验对克雷伯菌属,变形杆菌属,大肠杆菌和肠杆菌属的敏感性。分别为84%,22%,76%和62%,而CTX-CLAV的分别为95%,97%,94%和83%。 CPD-CLAV和CTZ-CLAV为90%,CPD-CLAV和CTX-CLAV为95%,CTZ-CLAV和CTX-CLAV为100%。 ESBL的生产在肠杆菌科中非常普遍。在克雷伯菌属高发地区,使用对CXM的抗性作为ESBL筛查标准是一种合适的选择。不是主要的ESBL生产商。尽管以测试更多分离株为代价,该筛选标准可以简化筛选测试并提高其灵敏度。 CTX-CLAV组合比ESTZ-CLAV组合更能证实ESBL生产者,并且不同物种之间的敏感性也不同。结合CTZ-CLAV和CTX-CLAV测试可以检测到所有这些菌株。 CPD-CLAV没有提供任何额外的好处。