利奈唑胺对MRSA肺炎肥胖患者的疗效优于万古霉素

旧金山——抗微生物制剂和化疗跨学科会议上公布的一项美国全国回顾性队列分析显示，利奈唑胺对耐甲氧西林金黄色葡萄球菌(MRSA)肺炎肥胖患者的疗效优于万古霉素。

在该研究中，49例体重指数(BMI)≥30 kg/m²的患者通过静脉或口服方式接受600 mg(标准剂量)利奈唑胺治疗，每12 h给药1次。740例患者接受标准剂量万古霉素治疗。患者接受至少3天治疗。临床成功定义为第14天前在无死亡、治疗变更或插管情况下从ICU或普通病房出院。结果显示，利奈唑胺用药者的临床成功率高于万古霉素用药者(HR，1.77；95%CI，1.18~2.64)。

研究者表示不清楚产生这一结果的确切原因，有可能是因为万古霉素的剂量部分按体重计算，或是因为对肥胖患者给予的万古霉素剂量存在问题。即使BMI提示用药剂量需超过标准剂量，但临床医生出于对毒性的担心，通常不愿意这么做。尚不清楚该研究中的患者接受的万古霉素剂量是否充足。利奈唑胺在给药剂量上则较为简单直接，因此肥胖患者可能更易于接受正确的剂量。

除了上述结果之外，研究者还发现，接受利奈唑胺治疗的非肥胖患者的30天再住院率较低(HR，0.60；95%，CI 0.37~0.97)。在其他预后方面，两种药物之间无差异。

该研究获辉瑞和退伍军人事务部资助。研究者声明与辉瑞存在利益关系。

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By: M. ALEXANDER OTTO, Clinical Endocrinology News Digital Network

SAN FRANCISCO – Linezolid works better than vancomycin in obese patients with MRSA pneumonia, according to an industry-supported analysis.

Clinical success – ICU or hospital discharge by day 14 in the absence of death, therapy change, or intubation – was more likely among 49 patients with body-mass-indices of 30 or more treated with 600 mg of linezolid IV or orally every 12 hours, the standard dose, than among 740 treated with standard dosing of vancomycin (HR 1.77, 95% CI 1.18-2.64). The findings come from a national retrospective cohort analysis of Veterans Affairs hospital data. The study was funded in part by Pfizer, which markets linezolid as Zyvox.

"Clinical success rates were higher [in obese patients] with linezolid. We don’t know exactly why," lead investigator Aisling Caffrey, Ph.D., assistant professor of pharmacoepidemiology at the University of Rhode Island College of Pharmacy in Kingston, R.I., said at the Interscience Conference on Antimicrobial Agents and Chemotherapy.

Maybe it was because vancomycin dosing is, in part, weight based and perhaps problematic for obese patients. Clinicians may be reluctant to exceed standard dosing even if BMIs suggest it, due to toxicity concerns; it’s unclear if patients in the study received adequate doses.

Linezolid "is a little more straightforward. Maybe obese patients were more likely to get the right dose," Dr. Caffrey said.

She and her coinvestigators hope to look further into the antibiotic treatment of MRSA pneumonia in the overweight population.

The investigation was a subgroup analysis of a larger MRSA pneumonia comparison study that found nonobese patients treated with linezolid were less likely to have 30-day hospital readmissions (HR 0.60, 95% CI 0.37-0.97). There were no other outcome differences between the drugs. Patients in the study were treated for at least 3 days.

The conference was sponsored by the American Society for Microbiology. Pfizer and the Department of Veterans Affairs funded the study. Two of the researchers were Pfizer employees. Dr. Caffrey\'s research is funded in part by Pfizer.