Starnes Margaret J, Brown Carlos V R, Morales Irma R, Hadjizacharia Pantelis, Salim Ali, Inaba Kenji, Rhee Peter, Demetriades Demetrios
Department of Surgery, Division of Trauma and Critical care, Los Angeles County and University of Southern California Medical Center, Los Angeles, CA 90033, USA.
J Crit Care. 2008 Dec;23(4):507-12. doi: 10.1016/j.jcrc.2008.02.007. Epub 2008 May 14.
Nosocomial infections in the intensive care unit (ICU) are well-known causes of morbidity and mortality in critically ill patients. Further complicating this issue is the ever-increasing number of multidrug-resistant pathogens. This study was designed to investigate and document changing microbial trends within the Los Angeles County/University of Southern California Medical Center surgical ICU (SICU), including drug-resistant pathogens.
A 6-year retrospective cohort study of all patients 18 to 85 years old with positive blood, urine, or sputum cultures admitted to an urban, level 1 trauma/SICU. Patients were identified through the Los Angeles County/University of Southern California Medical Center epidemiological records and computerized ICU database. The entire data set was analyzed according to pathogen classification schemes, culture date, type of infection, and with some patient characteristics including sex, average age, and Acute Physiology and Chronic Health Evaluation II score. Two groups were created to analyze changing trends: a past group (2000-2002 cultures) and a present group (2003-2005 cultures). Any repeated cultures were excluded, as was coagulase-negative Staphylococcus, which was considered a contaminant.
Over the past 6 years, there were 1164 SICU patients who developed 2260 positive cultures (346 blood, 1,685 respiratory, 229 urine). The average age of patients was 43 +/- 19 years, and their average Acute Physiology and Chronic Health Evaluation II score was 22 +/- 12. Of the 1164 patients, 76% were male, and 64% suffered trauma injuries. Although there was no difference in the rate of positive blood cultures caused by Gram-positive (GP) or Gram-negative (GN) organisms in the past and present groups (P = .32), GPs became more common in the present group for both respiratory (P < .0001) and urine (P = .004) cultures. In both blood and respiratory cultures, oxacillin-resistant Staphylococcus aureus was a more common GP pathogen (22% vs 7%, P = .004 and 20% vs 11%, P = .004) and represented a larger proportion of staphylococcal species in the present group (50% vs 21%, P = .01 and 30% vs. 21%, P = .04).
Our study found that within the SICU, GP organisms play an increasing pathogenic role in critical patients. Staphylococcal species have become more common pathogens in the last 6 years, with an increase in the proportion of drug-resistant strains (oxacillin-resistant S aureus). These findings illustrate the need to keep constant surveillance on microbial trends within the SICU, especially those among drug-resistant pathogens.
重症监护病房（ICU）内的医院感染是危重症患者发病和死亡的常见原因。使这一问题更加复杂的是多重耐药病原体的数量不断增加。本研究旨在调查并记录洛杉矶县/南加州大学医学中心外科ICU（SICU）内微生物趋势的变化，包括耐药病原体。
对所有年龄在18至85岁、血培养、尿培养或痰培养呈阳性且入住城市一级创伤/SICU的患者进行一项为期6年的回顾性队列研究。通过洛杉矶县/南加州大学医学中心的流行病学记录和ICU计算机数据库识别患者。根据病原体分类方案、培养日期、感染类型以及一些患者特征（包括性别、平均年龄和急性生理与慢性健康状况评估II评分）对整个数据集进行分析。创建了两组来分析变化趋势：过去组（2000 - 2002年培养物）和当前组（2003 - 2005年培养物）。排除任何重复培养物以及被视为污染物的凝固酶阴性葡萄球菌。
在过去6年中，有1164名SICU患者出现了2260次阳性培养（346次血培养、1685次呼吸道培养、229次尿培养）。患者的平均年龄为43±19岁，平均急性生理与慢性健康状况评估II评分为22±12。在1164名患者中，76%为男性，64%遭受创伤。尽管过去组和当前组中革兰氏阳性（GP）或革兰氏阴性（GN）菌引起的血培养阳性率无差异（P = 0.32），但在当前组中，GP菌在呼吸道培养（P < 0.0001）和尿培养（P = 0.004）中更为常见。在血培养和呼吸道培养中，耐苯唑西林金黄色葡萄球菌都是更常见的GP病原体（分别为22%对7%，P = 0.004和20%对11%，P = 0.004），并且在当前组中占葡萄球菌属的比例更大（分别为50%对21%，P = 0.01和30%对21%，P = 0.04）。
我们的研究发现，在SICU内，GP菌在危重症患者中发挥着越来越重要的致病作用。在过去6年中，葡萄球菌属已成为更常见的病原体，耐药菌株（耐苯唑西林金黄色葡萄球菌）的比例有所增加。这些发现表明有必要持续监测SICU内的微生物趋势，尤其是耐药病原体中的趋势。
