Immunomodulatory intervention in sepsis by multidrug-resistant Pseudomonas aeruginosa with thalidomide: an experimental study

BACKGROUND: Thalidomide is an inhibitor of tumour necrosis factor-alpha (TNFα) that has been proven effective for the treatment of experimental sepsis by Escherichia coli. It was tested whether it might behave as an effective immunomodulator in experimental sepsis by multidrug-resistant (MDR) Pseudomonas aeruginosa. METHODS: Sepsis was induced by the intraperitoneal injection of 1 × 10(8 )cfu/kg inoculum of the test isolate in a total of 109 Wistar rats divided in three groups as follows: group A controls; group B administered seed oil 30 minutes before bacterial challenge; and group C administered 50 mg/kg of thalidomide diluted in seed oil 30 minutes before bacterial challenge. Blood was sampled for estimation of endotoxins (LPS), TNFα, interferon-gamma (IFNγ), nitric oxide (NO) and malondialdehyde (MDA). LPS was measured by the QCL-1000 LAL assay, TNFα and IFNγ by ELISA, NO by a colorimetric assay and MDA by the thiobarbiturate assay. RESULTS: Mean (± SE) survival of groups A, B and C were 18.60 ± 1.84, 12.60 ± 0.60 and 30.50 ± 6.62 hours (p of comparisons A to C equal to 0.043 and B to C equal to 0.002). Decreased TNFα and NO levels were found in sera of animals of group C compared to group A. Plasma levels of LPS, MDA and IFNγ did not differ between groups. CONCLUSION: Intake of thalidomide considerably prolonged survival in experimental sepsis by MDR P.aeruginosa an effect probably attributed to decrease of serum TNFα

Detrimental effect of apoptosis of lymphocytes at an early time point of experimental abdominal sepsis

<p>Abstract</p> <p>Background</p> <p>Apoptosis of lymphocytes is considered a late sequelum in the sepsis cascade. The role of apoptosis of lymphocytes as a driver of final outcome was investigated.</p> <p>Methods</p> <p>Abdominal sepsis was induced after cecal ligation and puncture (CLP) in 31 rabbits. Blood was sampled at serial time intervals and peripheral blood mononuclear cells (PBMCs) were isolated. Apoptosis of lymphocytes and monocytes was measured through flow cytometric analysis. PBMCs were stimulated with LPS and Pam3Cys for the release of tumor necrosis factor-alpha (TNFα). Tissue bacterial growth was quantitatively measured. In a second set of experiments, CLP was performed in another 40 rabbits; 20 received single intravenous infusions of ciprofloxacin and of metronidazole 4 hours after surgery.</p> <p>Results</p> <p>Animals were divided into two groups based on the percentage of lymphocyte apoptosis at 4 hours after surgery; less than or equal to 32% and more than 32%. Survival of the former was shorter than the latter (p: 0.017). Tissue growth was similar between groups. Apoptosis of lymphocytes and of monocytes was lower in the former group over follow-up. Release of ΤNFα did not differ. The above findings on survival were repeated in the second set of experiments. Administration of antimicrobials prolonged survival of the former group (p: 0.039) but not of the latter group (pNS).</p> <p>Conclusions</p> <p>Lymphocyte apoptosis at an early time point of experimental peritonitis is a major driver for death. A lower percentage of apoptosis leads earlier to death. Antimicrobials were beneficial even at that disease state.</p

In vitro antimicrobial effects of aztreonam, colistin, and the 3-drug combination of aztreonam, ceftazidime and amikacin on metallo-β-lactamase-producing Pseudomonas aeruginosa

<p>Abstract</p> <p>Background</p> <p>There are limited choice of antimicrobial agents to treat infection with metallo-<it>β</it>-lactamase-producing <it>Pseudomonas aeruginosa</it>. We evaluate the antimicrobial effects of aztreonam alone, colistin alone and the 3-drug combination of aztreonam, ceftazidime and amikacin on 23 strains of metallo-<it>β</it>-lactamase-producing <it>P. aeruginosa </it>by time-killing tests.</p> <p>Methods</p> <p>Strains used were from different hospitals in Japan and had different pulse-field gel electrophoresis patterns by restriction with <it>Spe</it>I. The minimum inhibitory concentrations of 11 antimicrobial agents (piperacillin, piperacillin/tazobactam, imipenem, meropenem, aztreonam, ceftazidime, amikacin, tobramycin, arbekacin, ciprofloxacin and colistin) were determined using the agar dilution test. The effects of aztreonam, colistin and the combination of aztreonam, ceftazidime and amikacin were determined by time-killing studies.</p> <p>Results</p> <p>Bacteriostatic effects after 6 hours of drug exposure were observed in 12 strains (52.2%) of 23 strains of metallo-<it>β</it>-lactamase-producing <it>P. aeruginosa </it>with 48 mg/l aztreonam, in 19 strains (82.6%) with the 3-drug combination of 16 mg/l aztreonam, 16 mg/l ceftazidime, and 4 mg/l amikacin, and in 23 strains (100%) with 2 mg/l colistin. Bactericidal effects after 6 h drug exposure were observed in 1 strain (4.3%) with 48 mg/l aztreonam, in 8 strains (30.4%) with the 3-drug combination and in all 23 strains (100%) with 2 mg/l colistin.</p> <p>Conclusion</p> <p>Evaluation of <it>in vitro </it>antimicrobial effects on metallo-<it>β</it>-lactamase-producing <it>P. aeruginosa </it>revealed relatively good effects of the 3-drug combination of aztreonam, ceftazidime and amikacin and marked effects of colistin.</p

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

Procalcitonin (PCT) and C-reactive Protein (CRP) as severe systemic infection markers in febrile neutropenic adults

Abstract\ud \ud \ud \ud Background\ud \ud Procalcitonin (PCT) is an inflammatory marker that has been used as indicator of severe bacterial infection. We evaluated the concentrations of PCT as a marker for systemic infection compared to C-reactive protein (CRP) in patients neutropenic febrile.\ud \ud \ud \ud Methods\ud \ud 52 adult patients were enrolled in the study. Blood sample was collected in order to determine the serum concentrations of PCT, CRP and other hematological parameters at the onset of fever. The patients were divided into 2 groups, one with severe infection (n = 26) and the other in which the patients did not present such an infection (n = 26). Then PCT and CRP concentrations at the fever onset were compared between groups using non parametric statistical tests, ROC curve, sensitivity, specificity, likelihood ratio, and Spearman's correlation coefficient.\ud \ud \ud \ud Results\ud \ud The mean of PCT was significantly higher in the group with severe infection (6.7 ng/mL versus 0.6 ng/mL – p = 0.0075) comparing with CRP. Serum concentrations of 0.245 ng/mL of PCT displayed 100% de sensitivity and 69.2% specificity. PCT concentrations of 2,145 ng/mL presented a likelihood ratio of 13, which was not observed for any concentration of CRP.\ud \ud \ud \ud Conclusion\ud \ud PCT seems to be an useful marker for the diagnosis of systemic infection in febrile neutropenic patients, probably better than CRP

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