In Vitro Effects of Brodimoprim on Human Polymorphonuclear Leukocyte Functions. Preliminary Results

Effect of montelukast on polymorphonuclear leukocyte functions in asthmatic patients

Leukotriene receptor antagonists are being used widely in the treatment of bronchial asthma. They have been shown to possess anti-inflammatory properties, but there is no sufficient data about their effects on polymorphonuclear leukocyte functions. The aim of this study was to investigate the effects of montelukast, a specific cysteinyl leukotriene-1 receptor antagonist, on human polymorphonuclear leukocyte (PMN) functions (phagocytic and intracellular killing activity) in asthmatic patients. Fifteen mild to moderate asthmatic patients were included in the study. They were treated with montelukast (10 mg/day per os) in addition to their previous medications for 2 weeks. Whole blood samples of patients were taken before and after this treatment period. Phagocytic activities and intracellular killing activities of polymorphonuclear leukocytes isolated from whole blood samples were tested by using appropriate technics. Phagocytic and intracellular killing activities of PMNs were significantly increased (p<0.001, p<0.05) by montelukast compared to those before treatment. These results show that montelukast has an enhancing effect on PMN functions in asthmatic patients.

In vitro effect of cefodizime, imipenem/cilastatin and co-trimoxazole on dexamethasone and cyclosporin A depressed phagocytosis

Phagocytosis is an important part of the host defense against infection. Antibiotics can influence phagocytic function. In the present study, leukocyte metabolic response to phagocytic challenge by latex was assessed in relation to in vitro addition of cotrimoxazole, imipenem/cilastatin, cefodizime, dexamethasone (DXM), and/or cyclosporin A (CsA). Using latex particles as phagocytic challenge, glucose-1-14C utilization and 14CO2 production were measured by liquid scintillation counting. The phagocytic response was impaired by in vitro addition of DXM or CsA and this setup was used as an experimental model of immunodepression. The addition of co-trimoxazole to control samples (without DXM or CsA) depressed the response to latex challenge, whereas imipenem and cefodizime had a neutral effect. In the presence of DXM, co-trimoxazole induced a further decrease. The depressive effect of DXM was partially neutralized in the presence of cefodizime. With CsA depression, co-trimoxazole also induced a further decrease, imipenem had a neutral effect, while cefodizime partially restored the CsA suppressed reaction. Co-trimoxazole depressed the phagocytic response, imipenem had a neutral effect, whereas cefodizime restored the experimentally induced immunosuppression.

Brodimoprim: effects of subminimal inhibitory concentrations on virulence traits of respiratory and urinary tract pathogens, and on plasmid transfer and stability

The effects of brodimoprim, a new trimethoprim analogue, on several virulence traits of respiratory and urinary tract pathogens exposed to sub-lethal levels of the drug was studied. Adherence to tracheal epithelial cells was inhibited by brodimoprim in Klebsiella pneumoniae (41-67% reduction), Moraxella catarrhalis (87-90%) and Haemophilus influenzae (0-53%), while in Streptococcus pneumoniae binding was unaffected. With buccal epithelial cells the comparison between treated and control bacteria indicated statistically significant reduction in adherence with both S.pneumoniae and H.influenzae, (P < 0.015). With M.catarrhalis and Streptococcus pyogenes only marginal changes were detected (P > 0.05). Exoenzyme and capsule production were assessed in at least three isolates of diverse respiratory pathogens grown in the presence of sub-lethal levels of the new agent. The drug affected protease and beta-hemolysin (alpha-toxin) production in both oxacillin-susceptible and -resistant S.aureus. On the contrary, synthesis of lipase, DNase, coagulase, and beta-lactamase (S.aureus), pneumolysin (S.pneumoniae), streptolysin S, DNase, and protease (S.pyogenes), capsule (K.pneumoniae, H.influenzae and S.pneumoniae), and beta-lactamase (K.pneumoniae, H.influenzae and M.catarrhalis) were not inhibited by subminimal inhibitory concentrations (sub-MICs) of the drug. Finally, motility was blocked in urinary pathogens E.coli, P.mirabilis and P.aeruginosa, while in this latter microorganism pigment production was also affected. High molecular weight low-copy F'lac, and low molecular weight high-copy pHSG298 plasmids were eliminated from E.coli treated with sub-MIC concentrations of brodimoprim. The incidence and cured cells ranged from 9% for F'lac to 23% for pHSG298. F'lac transfer was also inhibited by the drug. When conjugation was carried out with bacteria exposed to brodimoprim (5XMIC), a reduction (50%) in the number of recombinants was noted in comparison to the control. The fact that brodimoprim interferes with the expression of some virulence traits, in particular with adherence, at sub-MIC levels may assist the drug in eradicating respiratory pathogens from the epithelial lining, thus diminishing the probability of reinfection.