Center for Disease Dynamics, Economics and Policy, Washington, DC, United States of America.
PLoS One. 2011;6(9):e25298. doi: 10.1371/journal.pone.0025298. Epub 2011 Sep 26.
Knowledge of seasonal trends in hospital-associated infection incidence may improve surveillance and help guide the design and evaluation of infection prevention interventions. We estimated seasonal variation in the frequencies of inpatient bloodstream infections (BSIs) caused by common bacterial pathogens and examined associations of monthly BSI frequencies with ambient outdoor temperature, precipitation, and humidity levels.
A database containing blood cultures from 132 U.S. hospitals collected between January 1999 and September 2006 was assembled. The database included monthly counts of inpatient blood cultures positive for several clinically important Gram-negative bacteria (Acinetobacter spp, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) and Gram-positive bacteria (Enterococcus spp and Staphylococcus aureus). Monthly mean temperature, total precipitation, and mean relative humidity in the postal ZIP codes of participating hospitals were obtained from national meteorological databases.
A total of 211,697 inpatient BSIs were reported during 9,423 hospital-months. Adjusting for long-term trends, BSIs caused by each gram-negative organism examined were more frequent in summer months compared with winter months, with increases ranging from 12.2% for E. coli (95% CI 9.2-15.4) to 51.8% for Acinetobacter (95% CI 41.1-63.2). Summer season was associated with 8.7% fewer Enterococcus BSIs (95% CI 11.0-5.8) and no significant change in S. aureus BSI frequency relative to winter. Independent of season, monthly humidity, monthly precipitation, and long-term trends, each 5.6°C (10°F) rise in mean monthly temperature corresponded to increases in gram-negative bacterial BSI frequencies ranging between 3.5% for E. coli (95% CI 2.1-4.9) to 10.8% for Acinetobacter (95% CI 6.9-14.7). The same rise in mean monthly temperature corresponded to an increase of 2.2% in S. aureus BSI frequency (95% CI 1.3-3.2) but no significant change in Enterococcus BSI frequency.
Summer season and higher mean monthly outdoor temperature are associated with substantially increased frequency of BSIs, particularly among clinically important gram-negative bacteria.
了解医院相关性感染发病率的季节性趋势可能有助于加强监测，并有助于指导感染预防干预措施的设计和评估。我们评估了常见细菌病原体引起的住院患者血流感染（BSI）的频率的季节性变化，并研究了每月 BSI 频率与环境室外温度、降水和湿度水平之间的关系。
我们组建了一个包含 1999 年 1 月至 2006 年 9 月期间美国 132 家医院的血液培养物的数据库。该数据库包括几个临床重要的革兰氏阴性菌（不动杆菌属、大肠埃希菌、肺炎克雷伯菌和铜绿假单胞菌）和革兰氏阳性菌（肠球菌属和金黄色葡萄球菌）的每月住院血液培养阳性计数。从国家气象数据库中获取参与医院所在邮政区域的每月平均温度、总降水量和平均相对湿度。
在 9423 个医院月期间共报告了 211697 例住院 BSI。在调整长期趋势后，与冬季相比，检查的每种革兰氏阴性菌引起的 BSI 在夏季更为常见，增幅范围从大肠埃希菌的 12.2%（95%CI 9.2-15.4）到不动杆菌的 51.8%（95%CI 41.1-63.2）。夏季季节与肠球菌 BSI 减少 8.7%相关（95%CI 11.0-5.8），与冬季相比，金黄色葡萄球菌 BSI 频率没有明显变化。与季节无关，每月湿度、每月降水量和长期趋势，每月平均温度每升高 5.6°C（10°F），革兰氏阴性菌 BSI 频率分别增加 3.5%（95%CI 2.1-4.9）至 10.8%（95%CI 6.9-14.7）。同样的月平均温度升高对应金黄色葡萄球菌 BSI 频率增加 2.2%（95%CI 1.3-3.2），但肠球菌 BSI 频率没有明显变化。
夏季季节和较高的月平均室外温度与 BSIs 的频率显著增加有关，尤其是在重要的临床革兰氏阴性菌中。
