老年患者血流感染的病原学及危险因素分析

目的 了解老年患者血流感染(BSI)的病原菌分布及耐药性，探讨导致其发生多重耐药菌感染的危险因素及相关预后，为临床治疗和预防提供依据。方法 回顾性分析2014年1月-2017年12月天津市第五中心医院所有确诊为BSI的老年患者的临床血培养资料。结果 共221例老年BSI患者纳入研究，年龄在60~74岁之间的老年人比例最高(67.4%)，患者主要分布在肾内科和消化科，基础疾病以心血管疾病、糖尿病、肿瘤性疾病多见。共检出病原菌228株，其中革兰阴性菌占68.9%(157/228株)，革兰阳性菌占25.0%(57/228株)，真菌占4.8%(11/228株)，厌氧菌占1.3%(3/228株)。常见的病原菌依次为大肠埃希菌(37.3%)，肺炎克雷伯菌(14.9%)，金黄色葡萄球菌(8.8%)，凝固酶阴性葡萄球菌(8.3%)和铜绿假单胞菌(5.7%)。大肠埃希菌、肺炎克雷伯菌中产超广谱β-内酰胺酶(ESBL)株的比例分别为52.9%和23.5%。未检出碳青霉烯类耐药大肠埃希菌和肺炎克雷伯菌。金黄色葡萄球菌和凝固酶阴性葡萄球菌中甲氧西林耐药株的检出率分别为20%和57.9%。未发现耐万古霉素和利奈唑胺的葡萄球菌。多因素回归分析显示，年龄>65岁、合并3种及以上基础疾病是多重耐药菌感染的危险因素，血红蛋白<100g/L、合并3种及以上基础疾病、入住ICU是老年BSI患者死亡的独立危险因素。结论 老年BSI病原菌以革兰阴性菌为主，大肠埃希菌是最常见的病原菌。年龄>65岁、合并3种及以上基础疾病增加多重耐药菌感染的风险，血红蛋白<100g/L、合并3种及以上基础疾病、入住ICU提示老年BSI患者预后不佳。

Etiology and risk factors analysis of bloodstream infections in elderly patients

Objective To investigate the distribution and drug resistance of pathogens of bloodstream infections in elderly patients, particularly the risk factors and prognosis of multi-drug resistance bacteria infections, and provide evidence for clinical treatment and prevention of bloodstream infection (BSI). Methods Microbiological and clinical data were collected and reviewed retrospectively for the elderly patients with confirmed bloodstream infections who were treated as inpatients in the 5th Central Hospital of Tianjin from January 2014 to December 2017. Results A total of 221 patients were diagnosed. The elderly patients between 60 and 74 years old were dominant (67.4%). Patients mainly distributed in the nephrology and the gastroenterology departments. The most common basic illnesses were cardiovascular disease, diabetes, and tumor. A total of 228 pathogenic strains were detected, of which 68.9% were Gram-negative bacteria, 25.0% were Gram-positive bacteria, 4.8% were fungi, and 1.3% were anaerobes. The top five isolates were Escherichia coli (37.3%), Klebsiella pneumoniae (14.9%), Staphylococcus aureus (8.8%),coagulase negative Staphylococcus (8.3%), and Pseudomonas aeruginosa (5.7%). Proportion of extended-spectrum beta-lactamases (ESBL) producing strains in Escherichia coli was 52.9%, and proportion of ESBL-producing strains in Klebsiella pneumoniae was 23.5%. No carbapenem-resistant strains of Escherichia coli and Klebsiella pneumoniae were found. The percentage of methicillin-resistant S. aureus (MRSA) was 20% and the percentage of methicillin-resistant coagulase negative Staphylococcus (MRCNS) was 57.9%, respectively. Vancomycin or linezolid-resistant S. aureus or coagulase negative Staphylococcus were not detected. Multivariable regression analysis indicated that age>65 years old, combined with three or more underlying diseases were the risk factors for multi-drug resistance bacteria infections. HGB<100g/L, combined with three or more underlying diseases and ICU admission were the independent risk factors for the death of bloodstream infections in elderly patients. Conclusion The surveillance data indicated that Gram-negative bacteria played an important role in the bloodstream infections of elderly patients. Escherichia coli were the most common pathogens. These data suggested that age>65 years old, combined with three or more underlying diseases increased the risk of multi-drug resistance bacteria infections. The elderly patients with bloodstream infections, whose HGB was less than 100g/L, combined with three or more underlying diseases and admitted to ICU, had a poor