The Importance of Fever as a Predictive Symptom for the Potency of Host's Monocytes to Release Pro- and Anti-Inflammatory Mediators

Objective. To clarify whether time lapsing from advent of fever as a first sign of sepsis may be indicative of the potency of monocytes for the release of pro- and anti-inflammatory mediators. Methods. Monocytes were isolated from blood of 51 septic patients and 9 healthy donors. Monocytes were incubated in the absence and presence of patients' serum and concentrations of tumour necrosis factor-alpha (TNF α), interleukin (IL)-6, IL-10, and malondialdehyde (MDA) were estimated in supernatants. Patients were divided into three groups: group A: <12 hours; group B: 12—24 hours, and group C: >24 hours between initiation of fever and blood sampling. Results. TNF α of supernatants of groups B and C was higher than controls, as also were IL-6 of A and C, IL-10 of A and B, and MDA of A. IL-6 of group A was increased after addition of patients serum. A negative correlation was found between time from initiation of symptoms and IL-6 of monocyte supernatants incubated in the presence of patients serum. Median IL-6 of survivors was higher than nonsurvivors. Conclusion. Monocytes are potent for the release of pro- and anti-inflammatory mediators within the first 24 hours upon advent of fever related to sepsis; serum stimulates further release of IL-6 within the first 12 hours

Effect of Clarithromycin in Patients with Sepsis and Ventilator-Associated Pneumonia

Background. Because clarithromycin provided beneficiary nonantibiotic effects in experimental studies, its efficacy was tested in patients with sepsis and ventilator-associated pneumonia (VAP). Methods. Two hundred patients with sepsis and VAP were enrolled in a double-blind, randomized, multicenter trial from June 2004 until November 2005. Clarithromycin (1 g) was administered intravenously once daily for 3 consecutive days in 100 patients; another 100 patients were treated with placebo. Main outcomes were resolution of VAP, duration of mechanical ventilation, and sepsis-related mortality within 28 days. Results. The groups were well matched with regard to demographic characteristics, disease severity, pathogens, and adequacy of the administered antimicrobials. Analysis comprising 141 patients who survived revealed that the median time for resolution of VAP was 15.5 days and 10.0 days among placebo- and clarithromycin-treated patients, respectively (P=.011); median times for weaning from mechanical ventilation were 22.5 days and 16.0 days, respectively (P=.049). Analysis comprising all enrolled patients showed a more rapid decrease of the clinical pulmonary infection score and a delay for advent of multiple organ dysfunction in clarithromycin-treated patients, compared with those of placebo-treated patients (P=.047). Among the 45 patients who died of sepsis, time to death was significantly prolonged in clarithromycin-treated compared with placebo-treated patients (P=.004). Serious adverse events were observed in 0% and 3% of placebo- and clarithromycin-treated patients, respectively (P=.25). Conclusions. Clarithromycin accelerated the resolution of VAP and weaning from mechanical ventilation in surviving patients and delayed death in those who died of sepsis. The mortality rate at day 28 was not altered. Results are encouraging and render new perspectives on the management of sepsis and VA

Effect of the Novel Influenza A (H1N1) Virus in the Human Immune System

BACKGROUND: The pandemic by the novel H1N1 virus has created the need to study any probable effects of that infection in the immune system of the host. METHODOLOGY/PRINCIPAL FINDINGS: Blood was sampled within the first two days of the presentation of signs of infection from 10 healthy volunteers; from 18 cases of flu-like syndrome; and from 31 cases of infection by H1N1 confirmed by reverse RT-PCR. Absolute counts of subtypes of monocytes and of lymphocytes were determined after staining with monoclonal antibodies and analysis by flow cytometry. Peripheral blood mononuclear cells (PBMCs) were isolated from patients and stimulated with various bacterial stimuli. Concentrations of tumour necrosis factor-alpha, interleukin (IL)-1beta, IL-6, IL-18, interferon (FN)-alpha and of IFN-gamma were estimated in supernatants by an enzyme immunoassay. Infection by H1N1 was accompanied by an increase of monocytes. PBMCs of patients evoked strong cytokine production after stimulation with most of bacterial stimuli. Defective cytokine responses were shown in response to stimulation with phytohemagglutin and with heat-killed Streptococcus pneumoniae. Adaptive immune responses of H1N1-infected patients were characterized by decreases of CD4-lymphocytes and of B-lymphocytes and by increase of T-regulatory lymphocytes (Tregs). CONCLUSIONS/SIGNIFICANCE: Infection by the H1N1 virus is accompanied by a characteristic impairment of the innate immune responses characterized by defective cytokine responses to S.pneumoniae. Alterations of the adaptive immune responses are predominated by increase of Tregs. These findings signify a predisposition for pneumococcal infections after infection by H1N1 influenza

Clarithromycin is an effective immunomodulator when administered late in experimental pyelonephritis by multidrug-resistant Pseudomonas aeruginosa

BACKGROUND: To apply clarithromycin as an immunomodulatory treatment in experimental urosepsis by multidrug-resistant Pseudomonas aeruginosa. METHODS: Acute pyelonephritis was induced in 40 rabbits after inoculation of the test isolate in the renal pelvis. Therapy was administered upon signs of sepsis in four groups: A, controls; B, intravenous clarithromycin; C, amikacin; and D, both agents. Survival and vital signs were recorded; blood was sampled for culture and estimation of pro-inflammatory mediators; monocytes were isolated for determination of apoptotic rate and ex vivo TNFα secretion. Quantitative cultures and biopsies of organs were performed after death. RESULTS: Increased rectal temperature and oxygen saturation were found in groups B and D compared to A and C. Mean survival of groups A, B, C and D was 2.65, 7.15, 4.25 and 8.70 days respectively. No differences were noted between groups concerning bacterial load in blood and tissues and serum endotoxins. Serum MDA and total caspase-3 activity of monocytes of group D decreased following treatment compared to other groups. Negative correlation was detected between cytoplasmic caspase-3 and ex vivo secretion of TNFα of blood monocytes of group A; similar correlation was not found for any other group. Pathology scores of liver and lung of group B were lower than group A. CONCLUSION: Clarithromycin administered late in experimental urosepsis by multidrug-resistant P. aeruginosa prolonged survival and ameliorated clinical findings. Its effect is probably attributed to immunomodulatory intervention on blood monocytes

Kinetics of progenitor hemopoetic stem cells in sepsis: Correlation with patients survival?

BACKGROUND: Current theories underline the crucial role of pro-inflammatory mediators produced by monocytes for the pathogenesis of sepsis. Since monocytes derive from progenitor hemopoetic cells, the kinetics of stem cells was studied in peripheral blood of patients with sepsis. METHODS: Blood was sampled from 44 patients with septic syndrome due to ventilator-associated pneumonia on days 1, 3, 5 and 7 upon initiation of symptoms. Concentrations of tumour necrosis factor-alpha (TNFα), interleukin (IL)-6, IL-8 and G-CSF were estimated by ELISA. CD34/CD45 cells were determined after incubation with anti-CD45 FITC and anti-CD34 PE monocloncal antibodies and flow cytometric analysis. Samples from eight healthy volunteers served as controls. RESULTS: Median of CD34/CD45 absolute count of controls was 1.0/μl. Respective values of the total study population were 123.4, 112.4, 121.5 and 120.9/μl on days 1, 3, 5 and 7 (p < 0.0001 compared to controls). Positive correlations were found between the absolute CD34/CD45 count and the absolute monocyte count on days 1, 5 and 7. Survival was prolonged among patients with less than 310/μl CD34/CD45 cells on day 1 compared to those with more than 310/μl of CD34/CD45 cells (p: 0.022). Hazard ratio for death due to sepsis was 5.47 (p: 0.039) for CD34/CD45 cells more than 310/μl. Median IL-6 on day 1 was 56.78 and 233.85 pg/ml respectively for patients with less than 310/μl and more than 310/μl CD34/CD45 cells (p: 0.021). CONCLUSION: Stem cells are increased in peripheral blood over all days of follow-up compared to healthy volunteers. Patients with counts on day 1 less than 310/μl are accompanied by increased survival compared to patients with more than 310/μl

Efficacy and pharmacodynamics of linezolid, alone and in combination with rifampicin, in an experimantal model of methicillin-resistant staphylococcus aureus (MRSA) endocarditis

In order to investigate the in vivo pharmacodynamics of linezolid in an experimental model of aortic-valve endocarditis by methicillin-resistant Staphylococcus aureus and to evaluate the efficacy of linezolid, with or without rifampicin, on both valve vegetations and secondary foci of infection comparative to vancomycin, endocarditis was induced in 81 male rabbits. Treatment groups were: A: controls (n=16); B: linezolid (n=15); C: vancomycin (n=15); D: linezolid and rifampicin (n=15); E: linezolid relapse (n=11); F: vancomycin relapse (n=9). Therapy lasted five days in all groups, with survival of animals in groups E and F being recorded for an additional five days. Blood was drawn for determination of linezolid concentration and valve vegetations and kidney, liver, lung and spleen segments collected for culture. Survival in all groups was prolonged comparative to controls; bacterial load in valve vegetations was reduced by all treatment regimens, with linezolid exhibiting bactericidal effects. Bactericidal activity of linezolid was noted in all secondary foci of infection but lung, where addition of rifampicin was necessary for bactericidal effect. Cmax/MIC ratio of greater than 2.1 and an AUC0>inf/MIC ratio of greater than 2.9 were closely correlated to bactericidal action of linezolid following single dose of the drug. It is concluded that Cmax/MIC and AUC0>inf/MIC ratios are determinant of bacterial eradication following therapy with linezolid; linezolid is also very effective in control of secondary foci. Clinical studies are needed for the implementation of these findings in therapeutics