Gram-Negative Pneumonia

This study is designed to evaluate the clinical and antibacterial efficacy, safety and pharmacokinetics of the drug Fluorothiazinone compared to placebo to prevent nosocomial gram-negative bacterial infections with participation of patients on mechanical ventilation. The main objectives of this study are: * Evaluation of the clinical and antibacterial efficacy of the drug Fluorothiazinone in combination with standard measures for the prevention of nosocomial infections compared to placebo in combination with standard measures for the prevention of nosocomial infections for the prevention of nosocomial infections caused by bacterial gram-negative flora in patients on mechanical ventilation. * Evaluation of the safety and tolerability of the drug Fluorothiazinone in patients on mechanical ventilation. * Evaluation of the pharmacokinetics (in whole blood) of the drug Fluorothiazinone with a single daily dose of 2400 mg/day. Researchers will compare results for the treatment and the placebo arms.