ImageStream cytometry extends the analysis of phagocytosis and oxidative burst.

AIM: Phagocytosis is often measured using conventional microscopy and flow cytometry. ImageStream cytometry is a new technology that combines the advantages of both methods, enabling statistically robust microscopic applications. We compared ImageStream cytometry to flow cytometry in a whole blood model of phagocytosis with viable, fluorescence-marked Staphylococcus aureus. We furthermore measured the co-localization of intracellular bacteria to sites of oxidative burst, as well as changes in cell size and actin levels as a result of phagocytosis. EXPERIMENTAL DESIGN: Fluorescence-labeled S. aureus in a ratio of 5:1 bacteria per leukocyte were added to whole blood. Phagocytosis was stopped at different time points. After staining of neutrophils and lysis of erythrocytes, samples were analysed by ImageStream cytometry and flow cytometry. RESULTS: Phagocytosis and oxidative burst determined by flow cytometry and ImageStream cytometry showed strong correlation. In contrast to flow cytometry, ImageStream cytometry easily detected and excluded extracellular adherent bacteria from the measurement of phagocytosis, and enumerated the bacteria within each neutrophil. Using the Bright Detail Similarity score, we identified a subset of neutrophils with intracellular bacteria co-localized to sites of oxidative burst activity. Phagocytosis resulted in an increase in cell size and actin polymerization as determined by an increase in phalloidin fluorescence intensity. CONCLUSIONS: We describe a simple whole blood image-based method for measuring bacterial phagocytosis and oxidative burst. ImageStream cytometry provides the spatial resolution to determine the number of bacteria ingested and the sub-cellular localization and trafficking patterns that enables a more complete evaluation of the phagocytic process.

Netrin-1 dampens pulmonary inflammation during acute lung injury.

RATIONALE: Acute lung injury (ALI) is an inflammatory disorder characterized by hypoxemia and diffuse infiltration of neutrophils into the alveolar space. The migration and extravasation of neutrophils is guided through positive guidance cues, such as chemokines. Recent work has identified the neuronal guidance protein netrin-1 to be a negative guidance cue for leukocyte migration and to hold antiinflammatory potential. OBJECTIVES: To test the role of pulmonary netrin-1 during ALI. METHODS: Pulmonary netrin-1 expression was evaluated during acute inflammation in vitro and in vivo; the netrin-1 promoter was studied using pGL4 luciferase reporter. ALI was induced through LPS inhalation and mechanical ventilation in wild-type, Ntn1(+/-), and A2BAR(-/-) animals. Exogenous netrin-1 was used to evaluate its impact on pulmonary inflammation. MEASUREMENTS AND MAIN RESULTS: Wild-type animals demonstrated repression of pulmonary netrin-1 after LPS inhalation. In vitro studies confirmed the repression of netrin-1. Studies in the putative netrin-1 promoter identified a nuclear factor-kappaB-dependent mechanism to be involved in this repression. Ntn1(+/-) animals demonstrated increased inflammatory changes after LPS inhalation compared with Ntn1(+/+) animals. Reconstitution with netrin-1 dampened the infiltration of neutrophils and cytokine production in the alveolar space. This effect was dependent on the adenosine 2b receptor. The importance of netrin-1 for the control of pulmonary inflammation could be corroborated in a model of ventilator-induced lung injury. CONCLUSIONS: Pulmonary netrin-1 levels are repressed during ALI. This results in pronounced pulmonary damage, an increased infiltration of neutrophils, and increased pulmonary inflammation. Exogenous netrin-1 significantly dampens the extent of ALI through the adenosine 2B receptor.

[Resuscitation algorithms for cardiac arrest and arrhythmias]. / Reanimation: Was ist neu? Notfallbehandlung von Herzstillstand und Arrhythmien.

Recently, guidelines for cardiopulmonary resuscitation have been updated by the European Resuscitation Council. Here we focus on cardiac arrest and arrhythmia algorithms for primary healthcare providers incorporating new recommendations.

Iloprost preserves renal oxygenation and restores kidney function in endotoxemia-related acute renal failure in the rat.

OBJECTIVE: To investigate that exogenous prostacyclin would counterbalance an endotoxemia-induced intrarenal vasoconstriction and would therefore have beneficial effects on kidney function. DESIGN: Prospective, randomized, controlled study. SETTING: University medical center research laboratory. SUBJECTS: Eighteen male Wistar rats. INTERVENTIONS: In anesthetized and ventilated animals, arterial blood pressure (mean arterial blood pressure [MAP]) and renal blood flow (RBF) were recorded. Renal microvascular Po2 (muPo2) and renal venous Po2 were continuously measured by phosphorescence lifetime technique. All animals received a 30-minute infusion of lipopolysaccharide (LPS) (2.5 mg/kg) to induce endotoxemia. One group of rats was not resuscitated. A second group received fluid resuscitation 90 minutes after stop of LPS infusion. In a third group of rats, the prostacyclin analogue iloprost (100 ng/kg/min) was continuously infused in addition to fluid resuscitation. Furthermore, in all the animals, plasma NOx levels, renal inducible nitric-oxide synthase (iNOS) messenger RNA (mRNA) expression, and creatinine clearance were determined. MEASUREMENTS AND MAIN RESULTS: During LPS infusion, MAP and RBF progressively dropped to 50% of baseline at 120 minutes. After an initial increase in MAP and RBF, start of fluid resuscitation with iloprost resulted in the stabilization of both parameters. All animals became anuric during endotoxemia. Only in animals receiving iloprost was creatinine clearance totally restored at the end of the experiment. Iloprost had no significant effects on average muPo2, but prevented the occurrence of cortical microcirculatory hypoxic areas. NOx levels and iNOS mRNA expression were significantly increased in all animals receiving LPS after 5 hours. There was no difference in NOx concentration between the different groups. In animals receiving iloprost, iNOS mRNA expression was significantly suppressed in the inner medulla. CONCLUSIONS: Iloprost significantly restored kidney function of endotoxemic rats to baseline values. This beneficial effect of iloprost on renal function might be addressed to an improvement in intrarenal oxygenation.

Effects of 1400W and/or nitroglycerin on renal oxygenation and kidney function during endotoxaemia in anaesthetized rats.

1. The pathogenesis of acute renal failure (ARF) in sepsis is multifactorial. The role of nitric oxide (NO) in septic ARF has been a source of controversy. We hypothesized that endotoxaemia-induced exacerbation of inducible nitric oxide synthase (iNOS)-related NO release impairs renal oxygenation and contributes to ARF in anaesthetized rats. 2. In the present study, rats received lipopolysaccharide (2.5 mg/kg) for 30 min. Two hours later, fluid resuscitation was started (HES130; 5 mL/kg per h after a 5 mL/kg bolus) supplemented either by the NO donor nitroglycerin (NTG; 0.5 µg/kg per min after a 2 µg/kg bolus), the selective iNOS inhibitor 1400 W (3 mg/kg per h after a 3 mg/kg bolus) or both. Systemic haemodynamics and renal microvascular Po2 (µPo(2)) were recorded continuously. Furthermore, creatinine clearance, plasma NO(x) (nitrate + nitrite + S-nitrosothiols) levels and the expression of iNOS mRNA were measured. 3. Endotoxaemia reduced renal blood flow, decreased mean arterial pressure, resulted in anuria and was associated with an increase in plasma NO(x) levels and renal iNOS expression. Renal µPo2 deteriorated gradually during endotoxaemia and there was a significant decrease in renal O(2) delivery and consumption. Manipulation of NO levels had no beneficial effect on systemic haemodynamics, renal µPo(2) or creatinine clearance over standard fluid resuscitation. The application of 1400 W+NTG significantly reduced plasma NO(x) levels compared with fluid resuscitation and NTG alone. 4. Neither iNOS inhibition, NO donation nor a combination of both showed beneficial effects on systemic haemodynamics, renal oxygenation and renal function compared with fluid resuscitation alone. Our results question the proposed key role of NO in the pathogenesis of septic ARF in rats.

Treatment with tigecycline of recurrent urosepsis caused by extended-spectrum-beta-lactamase-producing Escherichia coli.

A 25-year-old female was admitted to our intensive care unit with septic shock and multiorgan failure caused by extended-spectrum beta-lactamase-producing Escherichia coli originating from the right renal pelvis. A 16-day course of treatment with meropenem reversed the septic condition, but the infection recurred thereafter. The patient recovered fully after therapy was changed to tigecycline.

The inhibition of human neutrophil phagocytosis and oxidative burst by tricyclic antidepressants.

BACKGROUND: Tricyclic antidepressants are being investigated as long-acting analgesics for topical application in wounds or IV for postoperative pain relief. However, it remains unclear if tricyclic antidepressants affect the host defense and if reported toxic effects on neutrophils are of relevance in this setting. We therefore investigated the effects of amitriptyline, nortriptyline, and fluoxetine on human neutrophil phagocytosis, oxidative burst, and neutrophil toxicity in a human whole blood model. METHODS: Heparinized blood samples from healthy volunteers were incubated with amitriptyline, nortriptyline, or fluoxetine (10(-6) to 10(-3) M) for 0, 1, or 3 h. Staphylococcus aureus in a bacteria:neutrophil ratio of 5:1 and dihydroethidium (for the determination of oxidative burst) were added. Phagocytosis was stopped after 5, 10, 20, and 40 min. After lysis of red blood cells, samples were analyzed by flow cytometry. RESULTS: In concentrations up to 10(-4) M, none of the compounds affected neutrophil phagocytosis and oxidative burst. At 10(-3) M, all three compounds were highly toxic for neutrophils. Amitriptyline preserved morphological integrity, but completely suppressed neutrophil function. Nortriptyline and fluoxetine caused a marked disruption of neutrophils. The effects of the investigated antidepressants were not time-dependent. CONCLUSIONS: Phagocytosis and intracellular host defense are largely unaffected by antidepressants in concentrations of 10(-4) M and below. Our results confirm that antidepressants are highly toxic to neutrophils in millimolar concentrations. The neurotoxic effects and clinical side effects, but not effects on neutrophil functions, therefore, are likely to be the limiting factors in using antidepressants as analgesics.

[The intensive care in the German Diagnosis Related Groups-System]. / Die Intensivmedizin im deutschen DRG (Diagnosis Related Groups)-System.

The introduction of a prospective per case reimbursement system in the year 2004 in Germany put the high end intensive care medicine to a considerable financial risk on the basis of risk selection and high maintenance costs. To face this situation, the German Interdisciplinary Union for Intensive Care Medicine (DIVI) suggested to encode intensive care services as a DRG procedure and thus to make them relevant for reimbursement. That is the case now since 2007. The suggested procedure, called " complex intensive care treatment ", is based on a new intensive care scoring system ("Cost Predictor Score") which should quantify the costs per case. This paper provides an introduction into the GR-DRG (German Refined--Diagnosis Related Groups) health care reimbursement system and its financial implications for expensive hospital departments and presents a study carried out in the Anaesthesiological Intensive Care Unit of the Tübingen University Hospital examining the suitability of this new intensive care scoring system.

Influence of fluid resuscitation on renal microvascular PO2 in a normotensive rat model of endotoxemia.

INTRODUCTION: Septic renal failure is often seen in the intensive care unit but its pathogenesis is only partly understood. This study, performed in a normotensive rat model of endotoxemia, tests the hypotheses that endotoxemia impairs renal microvascular PO2 (microPO2) and oxygen consumption (VO2,ren), that endotoxemia is associated with a diminished kidney function, that fluid resuscitation can restore microPO2, VO2,ren and kidney function, and that colloids are more effective than crystalloids. METHODS: Male Wistar rats received a one-hour intravenous infusion of lipopolysaccharide, followed by resuscitation with HES130/0.4 (Voluven), HES200/0.5 (HES-STERIL 6%) or Ringer's lactate. The renal microPO2 in the cortex and medulla and the renal venous PO2 were measured by a recently published phosphorescence lifetime technique. RESULTS: Endotoxemia induced a reduction in renal blood flow and anuria, while the renal microPO2 and VO2,ren remained relatively unchanged. Resuscitation restored renal blood flow, renal oxygen delivery and kidney function to baseline values, and was associated with oxygen redistribution showing different patterns for the different compounds used. HES200/0.5 and Ringer's lactate increased the VO2,ren, in contrast to HES130/0.4. CONCLUSION: The loss of kidney function during endotoxemia could not be explained by an oxygen deficiency. Renal oxygen redistribution could for the first time be demonstrated during fluid resuscitation. HES130/0.4 had no influence on the VO2,ren and restored renal function with the least increase in the amount of renal work.

Activated protein C ameliorates impaired renal microvascular oxygenation and sodium reabsorption in endotoxemic rats.

INTRODUCTION: We aimed to test whether continuous recombinant human activated protein C (APC) administration would be able to protect renal oxygenation and function during endotoxemia in order to provide more insight into the role of coagulation and inflammation in the development of septic acute kidney injury. METHODS: In anesthetized, mechanically ventilated Wistar rats, endotoxemia was induced by lipopolysaccharide administration (10 mg/kg i.v. over 30 min). One hour later, the rats received fluid resuscitation with 0 (LPS + FR group; n = 8), 10 (APC10 group; n = 8), or 100 (APC100 group; n = 8) µg/kg/h APC for 2 h. Renal microvascular oxygenation in the cortex and medulla were measured using phosphorimetry, and renal creatinine clearance rate and sodium reabsorption were measured as indicators of renal function. Statistical significance of differences between groups was tested using two-way ANOVA with Bonferroni post hoc tests. RESULTS: APC did not have notable effects on systemic and renal hemodynamic and oxygenation variables or creatinine clearance. The changes in renal microvascular oxygenation in both the cortex (r = 0.66; p < 0.001) and medulla (r = 0.80; p < 0.001) were correlated to renal sodium reabsorption. CONCLUSION: Renal sodium reabsorption is closely correlated to renal microvascular oxygenation during endotoxemia. In this study, fluid resuscitation and APC supplementation were not significantly effective in protecting renal microvascular oxygenation and renal function. The specific mechanisms responsible for these effects of APC warrant further study.

Local anesthetic effects on human neutrophil priming and activation.

BACKGROUND: The anti-inflammatory effects of local anesthetics (LAs) are well documented. Local anesthetics in micromolar concentrations inhibit extracellular oxygen release in isolated neutrophils; the underlying mechanism seems to be an inhibition of leukocyte priming. It remains unclear, however, if first, these effects also can be observed in whole blood, and second, if the priming of other neutrophil functions is similarly attenuated by LAs. Furthermore, the effects of LAs on intracellular generation of oxidative species remain to be investigated. METHODS: Whole-blood samples from healthy volunteers were incubated for 0, 1, or 3 hrs with different concentrations (10 to 10 M) of either lidocaine, ropivacaine, QX314, or NaCl 0.9% as control. Dihydroethidium was added to quantify oxidative burst. Samples were primed with platelet-activating factor (PAF, 10 M) and/or activated with formyl-methyl-leucyl-phenylalanine (10 M) for 15 mins each. After staining for CD11b and lysis of erythrocytes, samples were analyzed by flow cytometry. RESULTS: Priming of leukocytes is a relevant mechanism in whole blood. Platelet-activating factor stimulates the priming of oxidative burst and CD11b expression. Lidocaine up to millimolar concentrations did not affect the PAF priming and formyl-methyl-leucyl-phenylalanine activation of oxidative burst. The priming of CD11b expression and the priming and activation of changes in cell morphology were significantly attenuated by lidocaine. CONCLUSIONS: The intracellular generation of reactive oxygen species remains largely unaffected by LAs in clinical concentrations. This suggests that the anti-inflammatory effects of LAs do not interfere with the host defense.

Low-dose dexamethasone-supplemented fluid resuscitation reverses endotoxin-induced acute renal failure and prevents cortical microvascular hypoxia.

There is growing evidence that impairment in intrarenal oxygenation and hypoxic injury might contribute to the pathogenesis of septic renal failure. An important molecule known to act on the renal microvascular tone and therefore consequently being involved in the regulation of intrarenal oxygen supply is NO. The main production of NO under septic conditions derives from iNOS, an enzyme that can be blocked by dexamethasone (DEX). In an animal model of endotoxin-induced renal failure, we tested the hypothesis that inhibition of iNOS by low-dose DEX would improve an impaired intrarenal oxygenation and kidney function. Twenty-two male Wistar rats received a 30-min intravenous infusion of LPS (2.5 mg/kg) and consecutively developed endotoxemic shock. Two hours later, in 12 animals, fluid resuscitation was initiated. Six rats did not receive resuscitation; four animals served as time control. In addition to the fluid, six animals received a bolus of low-dose DEX (0.1 mg/kg). In these animals, the renal iNOS mRNA expression was significantly suppressed 3 h later. Dexamethasone prevented the appearance of cortical microcirculatory hypoxic areas, improved renal oxygen delivery, and significantly restored oxygen consumption. Besides a significant increase in MAP and renal blood flow, DEX restored kidney function and tubular sodium reabsorption to baseline values. In conclusion, treatment with low-dose DEX in addition to fluid resuscitation reversed endotoxin-induced renal failure associated by an improvement in intrarenal microvascular oxygenation. Therefore, low-dose DEX might have potential application in the prevention of septic acute renal failure.

Local anesthetics time-dependently inhibit staphylococcus aureus phagocytosis, oxidative burst and CD11b expression by human neutrophils.

BACKGROUND AND OBJECTIVES: Local anesthetics have been shown to modulate neutrophil functions in a time-dependent manner, which might help to prevent inflammatory injury to the organism. However, if host defense mechanisms are affected similarly, the ability to eliminate bacteria might be reduced. We hypothesized that local anesthetics have time-dependent effects on phagocytosis of S. aureus, oxidative burst, and CD11b expression by human neutrophils. To test this hypothesis, we reanalyzed data from a previous study. METHODS: Blood samples from 11 healthy volunteers were incubated with lidocaine (1,846 mumol/L), bupivacaine (770 mumol/L) or ropivacaine (801 mumol/L) for 30 minutes. Thereafter, bacteria were added, either fluorescently labeled for determination of phagocytosis, or unstained for determination of oxidative burst and CD11b expression. After an additional incubation for 0, 10, 30, or 60 minutes, phagocytosis was stopped and neutrophils were stained with monoclonal antibodies for flow cytometric analysis. Data were analyzed by analysis of variance for repeated measurements. RESULTS: Lidocaine and bupivacaine inhibited neutrophil functions in a time-dependent manner (P < .05). Prolonged local anesthetic exposure reduced the fraction of ingesting neutrophils by 20% +/- 12% (mean +/- SD) and 7% +/- 7%, bacterial uptake by 19% +/- 16% and 14% +/- 12%, oxidative burst by 29% +/- 23% and 28% +/- 25%, and CD11b expression by 66% +/- 24% and 25% +/- 21% for lidocaine and bupivacaine, respectively. Ropivacaine exerted a time-dependent effect on CD11b expression only (24% +/- 34%; P < .05). CONCLUSIONS: Our results indicate that in a whole blood model, time-dependent effects of local anesthetics affect key neutrophil functions necessary for bacterial elimination. However, these effects only occur at concentrations that are unlikely to be routinely attained in the clinical setting, and concern about interfering with the host defense is likely unwarranted.

Acute decrease in renal microvascular PO2 during acute normovolemic hemodilution.

Large differences in the tolerance of organ systems to conditions of decreased O(2) delivery such as hemodilution exist. The kidney receives approximately 25% of the cardiac output and O(2) delivery is in excess of the oxygen demand under normal circumstances. In a rat model of acute normovolemic hemodilution (ANH), we studied the effect of reduced hematocrit on renal regional and microvascular oxygenation. Experiments were performed in 12 anesthetized male Wistar rats. Six animals underwent four steps of ANH (hematocrit 25, 15, 10, and <10%). Six animals served as time-matched controls. Systemic and renal hemodynamic and oxygenation parameters were monitored. Renal cortical (c) and outer medullary (m) microvascular PO(2) (microPO(2)) and the renal venous PO(2) (P(rv)O(2)) were continuously measured by oxygen-dependent quenching of phosphorescence. Despite a significant increase in renal blood flow in the first two steps of ANH, cmicroPO(2) and mmicroPO(2) dropped immediately. From the first step onward oxygen consumption (VO(2(ren))) became dependent on oxygen delivery (DO(2(ren))). With a progressive decrease in hematocrit, a significant correlation between microPO(2) and VO(2(ren)) could be observed, as well as a PO(2) gap between microPO(2) and P(rv)O(2). Furthermore, there was a high correlation between VO(2(ren)) and RBF over a wide range of flows. In conclusion, the oxygen supply to the renal tissue is becoming critical already in an early stage of ANH due to the combination of increased VO(2(ren)), decreased DO(2(ren)), and intrarenal O(2) shunt. This has clinical relevance as recent publications reporting that hemodilution during surgery forms a risk factor for postoperative renal dysfunction.

Dose-dependent influence of barbiturates but not of propofol on human leukocyte phagocytosis of viable Staphylococcus aureus.

OBJECTIVE: Deep sedation with barbiturates or propofol is a standard therapy for patients with critically elevated intracranial pressure. Such patients are prone to infectious complications, especially to pneumonias, which are most commonly caused by Staphylococcus aureus. Although various immunomodulatory effects of barbiturates have been described in vitro, their influence on the phagocytosis of viable S. aureus has yet to be investigated. Therefore, we examined the effects of thiopentone, methohexitone, and propofol on the phagocytosis of viable S. aureus. DESIGN: Laboratory study. SETTING: University laboratory. PATIENTS: Ten healthy volunteers aged 32.5 +/- 7 yrs. INTERVENTIONS: Blood sampling. MEASUREMENTS AND MAIN RESULTS: Whole blood samples were preincubated with different concentrations of thiopentone, methohexitone, and propofol, which is an isopropylphenol derivate. After viable S. aureus was added, phagocytosis was stopped at different time points. Leukocytes were then stained with monoclonal antibodies for flow cytometric analysis of granulocyte recruitment (ratio of ingesting granulocytes) and phagocytosis activity (fluorescence intensity of ingested bacteria). Both barbiturates inhibited granulocyte recruitment and phagocytosis activity in a dose-dependent manner, whereas propofol did not affect any of the investigated variables. At concentrations higher than 7.6 x 10(-3) M (for thiopentone, p < .008) and 1.1 x 10(-3) M (for methohexitone, p < .04), granulocyte recruitment and phagocytosis activity were significantly inhibited. The calculated inhibitory concentrations (IC50) of thiopentone for granulocyte recruitment and for phagocytosis activity were 1.3 x 10(-2) M and 1.1 x 10(-2) M, respectively. The corresponding values for methohexitone were 3.6 x 10(-3) M and 1.1 x 10(-3) M. CONCLUSIONS: Our in vitro model points at substantially different effects of barbiturates and propofol on phagocytosis of S. aureus, which is one of the most important pathogens in patients who need neuroprotective therapy. The inhibitory effects of both barbiturates demonstrate a strong dose-dependency, with more pronounced effects for methohexitone. Impairment of phagocytosis activity was more pronounced than granulocyte recruitment.

Selective decontamination of the digestive tract.

Ventilator-associated pneumonia usually originates from the patient's oropharyngeal microflora. In selective digestive decontamination, topical antibiotics are applied to the oropharynx and stomach for prevention of pneumonia and other infections, possibly reducing infection-related mortality. Selective digestive decontamination is also used for the prevention of gut-derived infections in acute necrotizing pancreatitis and liver transplantation. Despite numerous clinical trials, selective digestive decontamination remains controversial. Reduction of the incidence of pneumonia is accepted, but the extent of reduction is debated. Mortality was not reduced in most individual trials, but this finding was calculated in meta-analyses, especially for combined use of topical and systemic antibiotics in surgical ICU patients. Some investigators reported increased resistance and a shift to Gram-positive pathogens. Today, it appears that selective means not only selective suppression of pathogenic bacteria but also selection of appropriate groups of patients for underlying diseases and severity of illness, and selection of ICUs, where the endemic resistance patterns might allow the use of selective digestive decontamination at a relatively low risk for increased selection pressure.

Treatment of meningitis due to methicillin-resistant Staphylococcus epidermidis with linezolid.

Methicillin-resistant Staphylococcus epidermidis (MRSE) can cause nosocomial meningitis in the presence of prosthetic devices. Vancomycin is the treatment of choice, but its penetration into the cerebrospinal fluid is poor, especially in cases without severe meningeal inflammation. We successfully used linezolid to treat a case of posttraumatic MRSE meningitis with a low-level inflammatory response. Therapeutic effectiveness was documented microbiologically and by the simultaneous measurement of linezolid levels in serum and cerebrospinal fluid.

Influence of combined intravenous and topical antibiotic prophylaxis on the incidence of infections, organ dysfunctions, and mortality in critically ill surgical patients: a prospective, stratified, randomized, double-blind, placebo-controlled clinical trial.

We prospectively studied the impact of an antibiotic prophylaxis regimen on the incidence of infections, organ dysfunctions, and mortality in a predominantly surgical and trauma intensive care unit (ICU) population. A total of 546 patients were enrolled and stratified according to Acute Physiology and Chronic Health Evaluation (APACHE)-II scores. They were then randomized to receive either 2 x 400 mg of intravenous ciprofloxacin for 4 days, together with a mixture of topical gentamicin and polymyxin applied to the nostrils, mouth, and stomach throughout their ICU stay or to receive intravenous and topical placebo. When receiving prophylaxis, significantly fewer patients acquired infections (p = 0.001, risk ratio [RR], 0.477; 95% confidence interval [CI], 0.367-0.620), especially pneumonias (6 versus 29, p = 0.007), other lower respiratory tract infections (39 versus 70, p = 0.007), bloodstream infections (14 versus 36, p = 0.007), or urinary tract infections (36 versus 60, p = 0.042). Also, significantly fewer patients acquired severe organ dysfunctions (63 versus 96 patients, p = 0.0051; RR, 0.636; 95% CI, 0.463-0.874), especially renal dysfunctions (17 versus 38; p = 0.018). Within 5 days after admission, 24 patients died in each group, whereas 28 patients receiving prophylaxis and 51 receiving placebo died in the ICU thereafter (p = 0.0589; RR, 0.640; 95% CI, 0.402-1.017). The overall ICU mortality was not statistically different (52 versus 75 fatalities), but the mortality was significantly reduced for 237 patients of the midrange stratum with APACHE-II scores of 20-29 on admission (20 versus 38 fatalities, p = 0.0147; RR, 0.508; 95% CI, 0.295-0.875); there was still a favorable trend after 1 year (51 versus 60 fatalities; p = 0.0844; RR, 0.720; 95% CI, 0.496-1.046). Surveillance cultures from tracheobronchial, oropharyngeal, and gastric secretions and from rectal swabs did not show any evidence for the selection of resistant microorganisms in the patients receiving prophylaxis.

Correlation of meropenem plasma levels with pharmacodynamic requirements in critically ill patients receiving continuous veno-venous hemofiltration.

BACKGROUND: In patients with acute renal failure, the pharmacokinetics of meropenem depend on the operational characteristics of the renal replacement therapy. Dosage recommendations are based on the correlation of plasma levels with pharmacodynamic requirements. METHODS: Eight critically ill patients with acute renal failure were treated by continuous veno-venous hemofiltration with a filtrate flow of 1,600 ml/h and received 500 mg of meropenem every 12 h. Plasma and hemofiltrate concentrations of meropenem at steady state were determined by HPLC. RESULTS: Peak levels in plasma amounted to 39.5 +/- 10.5 mg/l (mean +/- SD) and trough levels were 2.4 +/- 1.5 mg/l. The minimal inhibitory concentration (MIC) for susceptible bacteria (4 mg/l) was covered for 40% of the dosing interval or longer in all patients. The MIC for intermediately susceptible organisms (8 mg/l) was covered for 33% in 6 of the 8 patients. The elimination half-life was prolonged to 3.63 +/- 0.77 h. The sieving coefficient of meropenem was 0.91 +/- 0.10 and the recovery in hemofiltrate amounted to 30.9 +/- 11.5% of the dose. CONCLUSIONS: A dosage of 500 mg twice daily provides appropriate serum levels for the treatment of infections caused by susceptible bacteria. A higher dosage is adequate for infections by intermediately susceptible bacteria or for renal replacement therapies with markedly higher filtrate flow rates.