Evaluation of a cefoxitin disk diffusion test for the routine detection of methicillin-resistant Staphylococcus aureus

Two oxacillin disk methods were compared with a cefoxitin disk diffusion test for detection of methicillin-resistant Staphylococcus aureus (MRSA), with PCR for mecA as the reference method. When tested with 115 MRSA and 350 methicillin-susceptible S. aureus isolates, the cefoxitin disk test (specificity 100%, sensitivity 96.5%) was superior to the oxacillin disk methods (specificity 99.1%, sensitivity 90.4%). Testing with both oxacillin and cefoxitin disks would give better sensitivity (100%) than the cefoxitin test alone, but at the expense of specificity (99.1%). The cefoxitin disk test required no special test conditions and would improve the reliability of routine tests for detection of MRSA.     

头孢西丁纸片扩散法检测耐甲氧西林金黄色葡萄球菌的研究

目的评价头孢西丁纸片扩散法检测耐甲氧西林金黄色葡萄球菌(MRSA)的准确性. 方法头孢西丁、苯唑西林药敏纸片分别采用K-B法检测 156株金黄色葡萄球菌临床分离株,同时采用PCR扩增mecA基因方法为检测MRSA的标准方法,比较两种方法的准确性. 结果 95株mecA基因阳性,61株mecA基因阴性;头孢西丁、苯唑西林药敏纸片K-B法的敏感性分别为98.9%和96.7%,特异性分别为98.4%和93.4%;头孢西丁纸片扩散法检测MRSA的敏感性和特异性高于苯唑西林纸片扩散法. 结论头孢西丁纸片扩散法是检测MRSA的可靠方法.     

金莲清热泡腾片联合头孢西丁钠治疗小儿急性上呼吸道感染的临床研究

目的探讨金莲清热泡腾片联合头孢西丁钠治疗小儿上呼吸道感染的临床疗效。方法选取2017年6月—2018年6月在河南省省立医院治疗的小儿上呼吸道感染患者102例,根据住院号分为对照组(51例)和治疗组(51例)。对照组静脉滴注头孢西丁钠注射液,100～150 mg/kg加入生理盐水100 mL,2次/d;治疗组在对照组治疗基础上口服金莲清热泡腾片,8 g/次,4次/d。两组患者经7 d治疗。观察两组患者临床疗效,同时比较治疗前后两组患者临床症状改善时间、肺功能和炎症因子水平。结果治疗后,对照组临床有效率为82.35%,显著低于治疗组的98.04%,两组比较差异有统计学意义(P0.05)。治疗后,治疗组患儿临床症状消失时间均明显短于对照组,两组比较差异具有统计学意义(P0.05)。治疗后,两组患儿呼吸频率(RR)、呼吸时间比(Ti/Te)均显著降低(P0.05),潮气量(VT)、达峰时间比(tPTEF/t E)显著升高(P0.05),且治疗组患儿肺功能明显好于对照组(P0.05)。治疗后,两组患儿超敏C反应蛋白(hs-CRP)、降钙素原(PCT)、白细胞介素-6(IL-6)、IL-13、肿瘤坏死因子-α(TNF-α)水平均明显下降(P0.05),且治疗组患儿上述炎症因子水平明显低于对照组(P0.05)。结论金莲清热泡腾片联合头孢西丁钠治疗小儿上呼吸道感染可显著改善患儿临床症状,促进患儿肺功能改善,降低患儿机体炎症反应。     

头孢西丁钠与头孢他啶治疗小儿支气管肺炎疗效分析

目的分析小儿支气管肺炎应用头孢西丁钠与头孢他啶治疗的效果。方法选取2012年9月~2014年9月我院诊治的小儿支气管肺炎患者246例分为两组,头孢西丁钠组给予头孢西丁钠合并盐酸氨溴索静脉滴注,头孢他啶组给予头孢他啶合并盐酸氨溴索静脉滴注,分析两组临床效果及成本。结果头孢他啶合并盐酸氨溴索对小儿支气管肺炎临床治疗效果优于头孢西丁钠,P0.05,差异具有统计学意义。结论头孢他啶抗菌谱较头孢西丁钠更广,但较头孢西丁钠的成本-效果值更大。     

Is There a Need to Revise the Antibiotic Concentration in Clinical and Laboratory Standards Institute-Recommended Oxacillin Screen Agar?

Introduction: In routine diagnostic microbiology laboratories, Clinical and Laboratory Standards Institute (CLSI) recommends the use of cefoxitin disc, in addition to oxacillin screen agar (OSA) of 6 μg/ml for the detection of methicillin-resistant Staphylococcus aureus (MRSA), whereas minimum inhibitory concentration values of oxacillin for S. aureus are ≤2 μg/ml (susceptible) and ≥4 μg/ml (resistant). Hence, the study was carried out to evaluate the ability of screen agar with lower concentrations of oxacillin to identify the isolates of MRSA and to compare this with cefoxitin disc diffusion (CDD). Materials and Methods: Six hundred and seventy-six isolates of S. aureus were screened for methicillin resistance by OSA with 2 μg/ml and 4 μg/ml and 6 μg/ml of oxacillin concentration as well as CDD. Polymerase chain reaction for mecA gene was carried out for all isolates which grew on OSA 2, 4 and 6 μg/ml regardless of their cefoxitin susceptibility. Latex agglutination test for penicillin-binding protein 2a was performed for the isolates which grew on OSA 2 and or 4 μg/ml but not on OSA 6 μg/ml. Results: Eight per cent of MRSA isolates was missed by using OSA 6 μg/ml, when compared with other methods. Sensitivities of OSA 2 μg/ml, OSA 6 μg/ml and CDD were found to be 100%, 92.5% and 97.5%, respectively, and specificities for the same were found to be 100%, 100% and 98%, respectively. As per FDA criteria, categorical agreement for OSA 2 μg/ml was found to be 100% in comparison with the reference broth microdilution method. No major and very major discrepancies were documented. Conclusion: Similar findings on a larger and more heterogeneous collection of isolates may indicate the need to revise the concentration of OSA to 2 μg/ml for the detection of MRSA.     

头孢西丁钠治疗急性肾盂肾炎64例疗效观察

目的：评价头孢西丁钠治疗急性肾盂肾炎的临床疗效和安全性。方法：采用随机、双盲、对照的方法,64例患者分为两组：治疗组32例给予试验药物头孢西丁钠2．0g/次静滴,每8小时一次,对照组32例予左氧氟沙星注射液0．2g/次,每日2次;治疗10-14d后评价疗效。结果：两组病人经治疗后症状、体征、恢复的时间无显著差异（P＞005）。试验组中治疗有效率90．6％,细菌学清除率87．1％;对照组中治疗有效率87．5％,细菌学清除率86．2％;两组比较差异无显著性（P＞0．05）。观察期间不良反应轻微。结论：头孢西丁钠用于急性肾盂肾炎时对常见致病菌大多敏感,细菌耐药少见,治疗效果好,无明显临床不良反应。     

Cefoxitin-based antibiotic therapy for extended-spectrum β-lactamase-producing Enterobacteriaceae prostatitis: a prospective pilot study

The emergence of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) infections requires re-assessment of therapeutic choices. Here we report the efficacy of cefoxitin-based antibiotic therapy for ESBL-E prostatitis. A prospective study including patients with ESBL-E prostatitis resistant to trimethoprim/sulfamethoxazole and fluoroquinolones from January 2014 to March 2016 was conducted. Cefoxitin was administered by continuous infusion for 3 weeks in the case of acute bacterial prostatitis or 6 weeks in the case of chronic bacterial prostatitis (CBP), with intravenous fosfomycin for the first 5 days. Urological investigations were performed to diagnose underlying urinary tract pathology. Clinical and microbiological efficacy were evaluated 3 months (M3) and 6 months (M6) after the end of therapy. A total of 23 patients were included in the study. The median patient age was 74 years (range 48–88 years). Of the 23 infections, 14 (61%) were CBP and 12 (52%) were healthcare-associated infections. The bacteria involved were Escherichia coli in 11 cases, Klebsiella pneumoniae in 10 cases and Klebsiella oxytoca in 2 cases. Clinical cure was observed in 19/23 patients (83%) at M3 and in 17/22 patients (77%) at M6. Urocultures were sterile in 13/23 patients (57%) at M3 and in 9/19 patients (47%) and M6. Urinary colonisation was observed in 6/19 patients (32%) with clinical cure at M3 and 5/14 patients (36%) with clinical cure at M6. No resistance to cefoxitin was detected. Surgical treatment was required for 7/23 patients (30%). In conclusion, cefoxitin-based antibiotic therapy is suitable for difficult-to-treat ESBL-E infections such as prostatitis.     

头孢西丁纸片扩散法检测耐甲氧西林葡萄球菌的临床应用评价

目的用PCR法检测葡萄球菌的mecA基因为参比方法,评价头孢西丁纸片扩散法检测耐甲氧西林葡萄球菌(MRS)的临床应用价值。方法临床分离的163株葡萄球菌,分别用头孢西丁、苯唑西林纸片扩散法、PCR法检测mecA基因,以PCR扩增法检测mecA基因作为参比方法进行比较。结果163株临床分离的葡萄球菌经PCR法检测mecA基因,阳性率为81.0%,其中,耐甲氧西林金黄色葡萄球菌(MRSA)和耐甲氧西林凝固酶阴性葡萄球菌(MRCNS)的发生率分别为74.1%和83.8%。头孢西丁、苯唑西林纸片扩散法用于检测MRSA与PCR法检测mecA基因有很好的一致性,其敏感性和特异性均为100.0%,而对于凝固酶阴性葡萄球菌,头孢西丁纸片扩散法比苯唑西林纸片扩散法检测MRS的敏感性和特异性高,敏感性分别为100.0%和94.3%,特异性分别为96.0%和88.0%。结论头孢西丁纸片扩散法检测耐甲氧西林葡萄球菌具有很高的灵敏度,但对于mecA基因阴性的凝固酶阴性葡萄球菌,用头孢西丁纸片法检测,约有5%菌株要误报为MRCNS。由于头孢西丁纸片扩散法操作简单,较苯唑西林纸片扩散法检出MRS的敏感度和特异性高,结果与PCR法检测mecA基因有很好的相关性,不需特殊仪器设备,可在临床微生物实验室常规开展。     

血流感染病原菌AmpC酶及相关耐药机制的初步研究

目的 了解血流感染病原菌中产AmpC β-内酰胺酶(简称AmpC酶)菌株的分布情况和临床病例特点,并对相关基因ampC和ampD进行初步研究.方法 收集2006年1月-2008年9月血流感染革兰阴性菌181株,分别采用头孢西丁初筛试验和三维试验筛选产AmpC酶菌株和高产AmpC酶菌株;对初筛试验阳性相关临床病例进行回顾性分析.同时对初筛试验阳性菌株ampC,ampD基因PCR扩增、测序和比对,Rep-PCR分析ampC阳性菌株基因型.结果 181株病原菌中头孢西丁初筛试验法检出产AmpC酶39株,概率为21.5%(39/181);三维试验法检出高产AmpC酶菌株的概率为43.6%(17/39).PCR结果显示ampC和ampD基因阳性率分别为41%(16/39)和56.4%(22/39).对16株ampC阳性菌进行基因测序,与GenBank相应ampC核酸序列比对发现同源性达98%-100%;2株阴沟肠杆菌ampD基因的测序发现在ampD基因羧基端存在可疑的突变位点.结论 本研究相关败血症患者血流耐药病原菌感染主要源自院内感染.在产AmpC酶的血流病原菌中,ampC基因突变比较少见,而阴沟肠杆菌ampD基因突变发生率比较高,且ampD蛋白羧基末端氨基酸的缺失或替代可能与AmpC酶去阻遏表达高度相关.     

基因扩增和3种表型筛查法检测耐甲氧西林葡萄球菌的应用评价

目的比较4种方法检测耐甲氧西林葡萄球菌(MRS)的阳性检出率、灵敏度和特异度,以便临床检测MRS时选择。方法用Vitek-32全自动细菌鉴定仪法、苯唑西林琼脂稀释法、头孢西丁纸片扩散法和mecA基因检测法分别检测175株葡萄球菌中的耐甲氧西林金黄色葡萄球菌(MRSA)和耐甲氧西林凝固酶阴性葡萄球菌(MRCNS),经行×列表资料的χ2检验比较阳性检出率,并以mecA基因检测法为"金标准"计算其他3种方法的灵敏度和特异度。结果4种方法检出MRSA的阳性率无差别(χ2=1.640,P>0.05),但检测MRCNS的阳性率有差别(χ2=9.478,P<0.05),其中Vitek-32全自动细菌鉴定仪法和苯唑西林琼脂稀释法检出MRCNS的阳性率高于mecA基因检测法;3种表型检测法检测MRSA的灵敏度和特异度分别为100%、96.3%、96.3%和88.2%、100%、100%,检测MRCNS的灵敏度均为100%,特异度分别为50%、46.1%和65.4%。结论最终判定MRS时,要考虑到mecA基因和苯唑西林最低抑菌浓度两个因素,并区别对待mecA基因介导的MRS和非mecA基因介导的MRS。