Elke Halle

Stroke-induced Immunodeficiency Promotes Spontaneous Bacterial Infections and Is Mediated by Sympathetic Activation Reversal by Poststroke T Helper Cell Type 1–like Immunostimulation

Infections are a leading cause of death in stroke patients. In a mouse model of focal cerebral ischemia, we tested the hypothesis that a stroke-induced immunodeficiency increases the susceptibility to bacterial infections. 3 d after ischemia, all animals developed spontaneous septicemia and pneumonia. Stroke induced an extensive apoptotic loss of lymphocytes and a shift from T helper cell (Th)1 to Th2 cytokine production. Adoptive transfer of T and natural killer cells from wild-type mice, but not from interferon (IFN)-γ–deficient mice, or administration of IFN-γ at day 1 after stroke greatly decreased the bacterial burden. Importantly, the defective IFN-γ response and the occurrence of bacterial infections were prevented by blocking the sympathetic nervous system but not the hypothalamo-pituitary-adrenal axis. Furthermore, administration of the β-adrenoreceptor blocker propranolol drastically reduced mortality after stroke. These data suggest that a catecholamine-mediated defect in early lymphocyte activation is the key factor in the impaired antibacterial immune response after stroke.

Preventive Antibacterial Therapy in Acute Ischemic Stroke: A Randomized Controlled Trial

Background Pneumonia is a major risk factor of death after acute stroke. In a mouse model, preventive antibacterial therapy with moxifloxacin not only prevents the development of post-stroke infections, it also reduces mortality, and improves neurological outcome significantly. In this study we investigate whether this approach is effective in stroke patients. Methods Preventive ANtibacterial THERapy in acute Ischemic Stroke (PANTHERIS) is a randomized, double-blind, placebo-controlled trial in 80 patients with severe, non-lacunar, ischemic stroke (NIHSS>11) in the middle cerebral artery (MCA) territory. Patients received either intravenous moxifloxacin (400 mg daily) or placebo for 5 days starting within 36 hours after stroke onset. Primary endpoint was infection within 11 days. Secondary endpoints included neurological outcome, survival, development of stroke-induced immunodepression, and induction of bacterial resistance. Findings On intention-to treat analysis (79 patients), the infection rate at day 11 in the moxifloxacin treated group was 15.4% compared to 32.5% in the placebo treated group (p = 0.114). On per protocol analysis (n = 66), moxifloxacin significantly reduced infection rate from 41.9% to 17.1% (p = 0.032). Stroke associated infections were associated with a lower survival rate. In this study, neurological outcome and survival were not significantly influenced by treatment with moxifloxacin. Frequency of fluoroquinolone resistance in both treatment groups did not differ. On logistic regression analysis, treatment arm as well as the interaction between treatment arm and monocytic HLA-DR expression (a marker for immunodepression) at day 1 after stroke onset was independently and highly predictive for post-stroke infections. Interpretation PANTHERIS suggests that preventive administration of moxifloxacin is superior in reducing infections after severe non-lacunar ischemic stroke compared to placebo. In addition, the results emphasize the pivotal role of immunodepression in developing post-stroke infections. Trial Registration Controlled-Trials.com ISRCTN74386719

Preventive Antibacterial Treatment Improves the General Medical and Neurological Outcome in a Mouse Model of Stroke

Background and Purpose— Epidemiological studies have demonstrated a high incidence of infections after severe stroke and their prominent role in morbidity and mortality in stroke patients. In a mouse model, it has been shown recently that stroke is coupled with severe and long-lasting immunosuppression, which is responsible for the development of spontaneous systemic infections. Here, we investigated in the same model the effects of preventive antibiotic treatment on survival and functional outcome of experimental stroke. Methods— Mice were subjected to experimental stroke by occlusion of the middle cerebral artery (MCAO) for 60 minutes. A group of mice received moxifloxacin (6×100 mg/kg body weight every 2 hours over 12 hours) either immediately or 12 hours after MCAO. Control animals received the vector only. Behavior, neurological deficit, fever, survival, and body weight were monitored over 14 days. In a subgroup, infarct volume was measured 4 days after MCAO. Microbiological assessment was based on cultures of lung tissue, blood, and feces of animals 3 days after stroke. For a dose-response study, moxifloxacin was given immediately after MCAO in different doses and at different time points. Results— Microbiological analyses of blood and lung tissue demonstrated high bacterial burden, mainly Escherichia coli, 3 days after stroke. Accordingly, we observed clinical and histological signs of septicemia and pneumonia. Moxifloxacin prevented the development of infections and fever, significantly reduced mortality, and improved neurological outcome. Conclusions— Preventive antibiotic treatment may be an important new therapeutical approach to improve outcome in patients with severe stroke.

How many infections are caused by patient-to-patient transmission in intensive care units?*

Objective:The proportion of intensive care unit (ICU)-acquired infections that are a consequence of nosocomial cross-transmission between patients in tertiary ICUs is unknown. Such information would be useful for the implementation of appropriate infection control measures. Design:A prospective cohort study during 18 months. Setting:Five ICUs from two university hospitals. Patients:All patients admitted for ≥48 hrs. Measurement:ICU-acquired infections were ascertained during daily bedside patient and chart reviews. Episodes of potential cross-transmission were identified by highly discriminating genetic typing of all clinical and surveillance isolates of the ten bacterial species most frequently associated with nosocomial infections in ICUs. Isolation of indistinguishable isolates in two or more patients defined potential transmission episodes. Main Results:During 28,498 patient days, 431 ICU-acquired infections and 141 episodes of nosocomial transmissions were identified. A total of 278 infections were caused by the ten species that were genotyped, and 41 of these (14.5%) could be associated with transmissions between patients. Conclusion:Infections acquired during treatment in modern tertiary ICUs are common, but a causative role of direct patient-to-patient transmission can only be ascertained for a minority of these infections on the basis of routine microbiological investigations.

Impact of adherence to standard operating procedures for pneumonia on outcome of intensive care unit patients.

Background:Pneumonia accounts for almost half of intensive care unit (ICU) infections and nearly 60% of deaths from nosocomial infections. It increases hospital stay by 7–9 days, crude mortality by 70% and attributable mortality by 30%. Objective:Our purpose was to assess the impact of standard operating procedures adapted to the local resistance rates in the initial empirical treatment for pneumonia on duration of first pneumonia episode, duration of mechanical ventilation, and length of ICU stay. Design:Prospective observational cohort study with retrospective expert audit. Setting:Five anesthesiologically managed ICUs at University hospital (one cardio-surgical, one neurosurgical, two interdisciplinary, and one intermediate care). Patients:Of 524 consecutive patients with ≥36 hr ICU treatment 131 patients with pneumonia on ICU were identified. Their first pneumonia episode was evaluated daily for adherence to standard operating procedures. Pneumonia was diagnosed according to the American Thoracic Society guidelines. Patients with >70% compliance were assigned to high adherence group (HAG), patients with ≤70% to low adherence group (LAG). Measurements and Results:HAG consisted of 45 (49 first episode) patients, LAG of 86 (82 first episode) patients, respectively. Mean duration of treatment of the first pneumonia episode was 10.11 ± 7.95 days in the LAG and 6.22 ± 3.27 days in the HAG (p = 0.001). Duration of mechanical ventilation was 317.59 ± 336.18 hrs in the LAG and 178.07 ± 191.33 hrs in the HAG (p = 0.017). Length of ICU stay was 20.24 ± 16.59 days in the LAG and 12.04 ± 10.42 days in the HAG (p = 0.001). Limitations:Barriers in compliance need further evaluation. Conclusion:Adherence to standard operating procedure is associated with a shorter duration of treatment of first pneumonia episode, a shorter duration of mechanical ventilation, and a shorter ICU stay.

Fluorescence in situ hybridisation (FISH) accelerates identification of Gram-positive cocci in positive blood cultures

Sepsis is a life-threatening disease with a high mortality rate. Rapid identification of blood culture isolates plays a crucial role in adequate antimicrobial therapy in sepsis patients. To accelerate microbiological diagnosis, a comprehensive panel of oligonucleotide probes for fluorescence in situ hybridisation (FISH) targeting Gram-positive cocci was compiled and evaluated on 428 positive blood culture specimens. By combining genus-specific and species-specific probes, the assay allowed discrimination of staphylococci, streptococci and enterococci as well as differentiation of therapy-relevant pathogens such as Staphylococcus aureus and Enterococcus faecium/durans. Furthermore, the newly designed FISH probes STREP2, ENCO and GRANU targeted Streptococcus pneumoniae/mitis, Enterococcus spp. (except E. faecalis) and Granulicatella adiacens group, respectively. The FISH assay achieved an overall sensitivity of 98.65% and a specificity of 99.0% and therefore allowed rapid and reliable molecular identification of Gram-positive cocci in blood culture specimens.

Long-term effect of computer-assisted decision support for antibiotic treatment in critically ill patients: a prospective ‘before/after’ cohort study

Objectives Antibiotic resistance has risen dramatically over the past years. For individual patients, adequate initial antibiotic therapy is essential for clinical outcome. Computer-assisted decision support systems (CDSSs) are advocated to support implementation of rational anti-infective treatment strategies based on guidelines. The aim of this study was to evaluate long-term effects after implementation of a CDSS. Design This prospective ‘before/after’ cohort study was conducted over four observation periods within 5 years. One preinterventional period (pre) was compared with three postinterventional periods: directly after intensive implementation efforts (post1), 2 years (post2) and 3 years (post3) after implementation. Setting Five anaesthesiological-managed intensive care units (ICU) (one cardiosurgical, one neurosurgical, two interdisciplinary and one intermediate care) at a university hospital. Participants Adult patients with an ICU stay of >48 h were included in the analysis. 1316 patients were included in the analysis for a total of 12 965 ICU days. Intervention Implementation of a CDSS. Outcome measures The primary end point was percentage of days with guideline adherence during ICU treatment. Secondary end points were antibiotic-free days and all-cause mortality compared for patients with low versus high guideline adherence. Main results Adherence to guidelines increased from 61% prior to implementation to 92% in post1, decreased in post2 to 76% and remained significantly higher compared with baseline in post3, with 71% (p=0.178). Additionally, antibiotic-free days increased over study periods. At all time periods, mortality for patients with low guideline adherence was higher with 12.3% versus 8% (p=0.014) and an adjusted OR of 1.56 (95% CI 1.05 to 2.31). Conclusions Implementation of computerised regional adapted guidelines for antibiotic therapy is paralleled with improved adherence. Even without further measures, adherence stayed high for a longer period and was paralleled by reduced antibiotic exposure. Improved guideline adherence was associated with reduced ICU mortality. Trial registration number ISRCTN54598675.

Linezolid-resistant Enterococcus faecium and Enterococcus faecalis isolated from a septic patient: report of first isolates in Germany.

Abstract.Here we report the first German case of necrotizing pancreatitis, peritonitis, and septic shock caused by linezolid-resistant Enterococcus faecium and Enterococcus faecalis.

Computer-assisted Decision Support for Changing Practice in Severe Sepsis and Septic Shock

Computer-assisted decision support systems (CDSS) are designed to improve infection management. The aim of this prospective, clinical pre- and post-intervention study was to investigate the influence of CDSS on infection management of severe sepsis and septic shock in intensive care units (ICUs). Data were collected for a total of 180 days during two study periods in 2006 and 2007. Of the 186 patients with severe sepsis or septic shock, 62 were stratified into a low adherence to infection management standards group (LAG) and 124 were stratified into a high adherence group (HAG). ICU mortality was significantly increased in LAG versus HAG patients (Kaplan–Meier analysis). Following CDSS implementation, adherence to standards increased significantly by 35%, paralleled with improved diagnostics, more antibiotic-free days and a shortened time until antibiotics were administered. In conclusion, adherence to infection standards is beneficial for patients with severe sepsis or septic shock and CDSS is a useful tool to aid adherence.

Neonatal Septicaemia—Incidence, Etiology and Outcome A 6‐year Analysis

Grauel, E. L., Halle, E., Bollmann, R., Buchholz, P. and Buttenberg, S. (Department of Neonatology, Pediatric Clinic and Institute of Medical Microbiology, University‐Hospital (Charité), Berlin, GDR). Neonatal septicaemia—incidence, etiology and outcome. A 6‐year analysis. Acta Paediatr Scand Suppl 360: 113, 1989.