Evaluation of combination therapies with colistin in an experimental mouse pneumonia model induced by carbapenem-resistant Acinetobacter baumannii strain.

The treatment options are limited in Acinetobacter baumannii infections. In this study, the effectiveness of colistin monotherapy and combinations of colistin with different antibiotics were investigated in an experimental pneumonia model induced by carbapenem-resistant A. baumannii strain. Mice in the study were divided into five groups as control (no treatment), colistin monotherapy, colistin + sulbactam, colistin + imipenem, and colistin + tigecycline combinations. The modified experimental surgical pneumonia model of Esposito and Pennington was applied to all groups. The presence of bacteria in blood and lung samples was investigated. Results were compared. In blood cultures, while there was no difference between the control and colistin groups, there was a statistical difference between the control and the combination groups (P = 0.029). When the groups were compared in terms of lung tissue culture positivity, there was a statistical difference between the control group and all treatment groups (colistin, colistin + sulbactam, colistin + imipenem, and colistin + tigecycline) (P = 0.026, P < 0.001, P < 0.001, and P = 0.002, respectively). The number of microorganisms that grew in the lung tissue was found to be statistically significantly lower in all treatment groups in comparison with the control group (P = 0.001). Both monotherapy and combination therapies of colistin were found to be effective in the treatment of carbapenem-resistant A. baumannii pneumonia, but the superiority of combination therapies over colistin monotherapy has not been demonstrated.

Selenium exerts protective effects on inflammatory cardiovascular damage: molecular aspects via SIRT1/p53 and Cyt-c/Cas-3 pathways.

BACKGROUND: Systemic inflammatory response could affect many systems. Cardiac dysfunction develops due to cardiovascular system damage and could be mortal. Selenium is a trace element that can be used as a dietary supplement and has antioxidant, anti-inflammatory, and anti-apoptotic properties. This study aims to evaluate the protective effects of selenium on cardiovascular damage via silenced information regulator 1 (SIRT1)/p53 and cytochrome C (Cyt-c)/ caspase-3 (Cas-3) pathways. METHODS AND RESULTS: Thirty-two rats were randomly divided into 4 groups as control, LPS (0.1 mg/kg, intraperitoneally(i.p.), 2-7 days) and LPS + Selenium (LPS-0.1 mg/kg, i.p., 2-7 days, selenium - 100 µg/kg, i.p., 1-7 days) and selenium (100 µg/kg, i.p., 1-7 days) group. On the 8th day of the experiment, rats were sacrificed. Blood samples and half of the left ventricles were collected for biochemical and genetic analysis. The remaining left ventricles and aorta were taken for histological and immunohistochemical analysis. In the LPS group myocardial hemorrhages, hyperemia, and endothelial cell loss were observed. Also, Cas-3 and vascular endothelial growth factor (VEGF) expressions; creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), tumor necrosis factor-alpha (TNF-α), ischemia modified albumin (IMA), total oxidant status (TOS), oxidative stress index (OSI) levels; p53, Cyt-c, Cas-3 mRNA expressions increased while total antioxidant status (TAS) levels, glutathione peroxidase (GPx) activity, SIRT1 mRNA expression decreased. Selenium treatment reversed all these changes. CONCLUSION: Selenium showed protective effects on cardiovascular injury via regulating SIRT1/p53 and Cyt-c/Cas-3 pathways. This study enlightened the possible usage of selenium on cardiotoxicity.