Infection after Acute Ischemic Stroke: Risk Factors, Biomarkers, and Outcome

SAGE-Hindawi Access to Research Stroke Research and Treatment Volume 2011, Article ID 830614, 8 pages doi:10.4061/2011/830614 Clinical Study Infection after Acute Ischemic Stroke: Risk Factors, Biomarkers, and Outcome Katja E. Wartenberg,1 Anett Stoll,2 Andreas Funk,3 Andreas Meyer,4 J. Michael Schmidt,5 and Joerg Berrouschot2 1 Department of Neurology, Martin Luther University Halle-Wittenberg, Ernst-Grube-Strasse 40, 06120 Halle (Saale), Germany 2 Department of Neurology, Klinikum Altenburger Land, Am Waldessaum 10, 04600 Altenburg, Germany 3 Department of General Surgery, Klinikum Altenburger Land, Am Waldessaum 10, 04600 Altenburg, Germany 4 Central Laboratory, Klinikum Altenburger Land, Am Waldessaum 10, 04600 Altenburg, Germany 5 Division of Neurocritical Care, Neurological Institute, Columbia University College of Physicians and Surgeons, 710 West 168th Street, New York, NY 10032, USA Correspondence should be addressed to Katja E. Wartenberg, Received 22 February 2011; Accepted 31 March 2011 Academic Editor: Byung Woo Yoon Copyright © 2011 Katja E. Wartenberg et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. The activation of inflammatory cascades triggered by ischemic stroke may play a key role in the development of infections. Methods. Patients admitted with ischemic stroke within 24 hours were prospectively enrolled. Biomarkers of infection were measured on days 1, 3, and 5. The patients were continuously monitored for predefined infections. Results. Patients with infection were older (OR 1.06 per year, 95% CI 1.01–1.11) and had a higher National Institute of Health Stroke Scale Score (NIHSS, OR 1.21, 95% CI 1.10–1.34), localization in the insula, and higher stroke volumes on diffusion-weighted imaging. The maximum temperature on days 1 and 3, leukocytes, interleukin-6, lipopolysaccharide-binding protein on days 1, 3, and 5, C-reactive protein on days 3 and 5, and procalcitonin on day 5 were higher and HLA-DR-expression on monocytes on days 1, 3, and 5 lower in patients with infection. Age and NIHSS predicted the development of infections. Infection was an independent predictor of poor functional outcome. Conclusions. Severe stroke and increasing age were shown to be early predictors for infections after stroke. 1. Introduction Infections complicating acute ischemic stroke contribute to mortality and poor functional outcome after stroke in most clinical studies [1–6]. Pneumonia occurs in 5–22% and is the most common cause of death in stroke patients [1–8]. The risk of infection is highest in the acute phase after stroke [4] which may be attributed to stroke-induced immunodepression syndrome (SIDS). SIDS is characterized by loss of lymphocytes through apoptosis, shift of T-helper cell 1 to 2 cytokine production, decreased monocyte count and function, and interferon γ deficiency which begins a few hours after ischemia and lasts for several weeks. These effects are associated with infection after stroke [9, 10]. Biomarkers may facilitate an early diagnosis of infection in patients with acute ischemic stroke [11]. In this study we attempted to define biomarkers of early infection, identify early predictors of infection during the hospital course after acute ischemic stroke and the impact of infection on functional outcome after 3 months. 2. Material and Methods 2.1. Patient Population. Patients admitted to our stroke unit during one year were enrolled in the study if they (1) had symptoms and signs of an acute ischemic stroke, (2) were treated within 24 hours after symptom onset, (3) had a premorbid modified Rankin Scale score (mRS) of 0 to 1, and (4) gave informed consent. Patients were excluded from the study if they (1) had an intracranial hemorrhage, hypoglycemia, or other causes of a new focal deficit, (2) 2 had contraindications against magnetic resonance imaging (MRI), (3) were taking antibiotics, (4) were immunocompromised by chemotherapy or acquired immunodeficiency syndrome, (5) had severe comorbidities, or (6) could not participate in the follow-up examination. The comprehensive stroke unit encompasses 8 monitored beds for stroke patients and 4 monitored beds with capacity for mechanical ventilation (neurointensive care unit). Patient recruitment was performed prospectively. The study was approved by the local ethics committee. Written informed consent was obtained from all patients (or their legal guardian) prior to participating in the study. 2.2. Clinical Management and Data. The patients were treated according to the guidelines of management of acute ischemic stroke [12, 13]. The patients were screened on admission (day 1); demographic data, medical history including the presence of an infection in the last two weeks and medications prior to admission (specifically antibiotics) and risk factors, and vital signs were obtained. The temperature was measured continuously utilizing the temperature probe of the urinary catheter if placed or an axillary temperature probe. The maximum daily temperature was charted on days 1 and 3. Clinical examination encompassed a general evaluation, the National Institute of Health Stroke Scale (NIHSS), and mRS [14]. The patients received an electrocardiogram, a focused MRI (diffusionweighted imaging = DWI and fluid attenuated inversion recovery imaging = FLAIR), and a chest radiograph on day 1. Laboratory markers on admission included a complete blood count with differential, renal, and liver function tests, cardiac enzymes, and a urine analysis. The inflammatory markers, white blood cells (WBCs), C-reactive protein (CRP) [15, 16], procalcitonin (PCT), interleukin-6 (IL-6) [16–20], HLA-DR-expression on monocytes (HLADRM) [16, 19, 21], and lipopolysaccharide-binding protein (LBP) [22], were collected on days 1, 3, and 5 along with the mean body temperature (measured every 1–4 hours). The biomarkers were measured by chemical luminescence immunoassay (Immulite DPC Biermann, Siemens Diagnostics, Germany) (IL-6, LBP), automated immunofluorescent assay (Kryptor Brahms Diagnostica, Berlin, Germany), immunoturbidimetry (AU 600 Olympus, Dallas, TX, USA) (CRP), electrical impedance or flow cytometry (SE 9000 Sysmex, Digitana, Horgen, Switzerland) (WBC), and flow cytometry (EPICS XL, Beckman Coulter, Fullerton, CA, USA) (HLADRM). Another focused MRI (DWI and FLAIR) was performed on days 5–7. The infarction and edema volumes were calculated on DWI (day 1) and FLAIR (days 5–7) using the planimetry method [23]. All infections and procedures, presence of dysphagia from admission through day 5, duration of hospital stay, the localization, and final etiology of the ischemic stroke according to the TOAST criteria [24] were recorded. Hospital procedures included the placement of urinary catheters in patients with urinary incontinence, requiring close mo (...truncated)