Morphometric and microbiological features of ventilator associated tracheobronchitis

Changes in the composition of the microbiota of the tracheobronchial tree in patients on prolonged mechanical ventilation can contribute to various disorders of the immune defense of the respiratory tract, damaging mucociliary clearance, and cause a strong inflammatory response, including the formation of ventilator-associated tracheobronchitis (VAT). The aim was to study the specifics of changes in the microflora and histopathology of the tracheobronchial tree in VAT. Over a 10 year period 975 bacteriological analyzes were carried out in 355 patients who were on extended mechanical ventilation for more than 48 hours. VAT is accompanied by a pronounced lymphoid-neutrophilic infiltration of the mucosa of the trachea and bronchi, and in a complicated course with the presence of a purulent-inflammatory and erosive-hemorrhagic component leads to a violation of the integrity of tissues due to destruction and necrosis. The leading pathogens were representatives of gram-negative flora of 65.8% (47-76%), gram-positive flora was detected in 17.5% (10-30%) of cases, fungi of the genus Candida in 16.5 (4-42%) cases. Analysis of the antibiograms of isolated cultures in patients on prolonged mechanical ventilation shows high resistance to a wide range of antibiotics, namely: acinetobacter spp. - high resistance to all antibiotics, except for imipenem (0% resistant strains), polymyxin (0%) and tetracyclines (7-15.4%). Imipenem (10.5%), polymyxin (10.5%), amikacin (31.5%) and cefoperazone/sulbactam (31.5%) are active against Esherichia coli. Klebsiella pneumoniae was susceptible to imipenem, amikacin, ofloxacin and inhibitor-protected antibiotics-cefoperazone/sulbactam, piperacillin/tazobactam. Staphylococcus aureus was susceptible to III generation cephalosporins (cefotaxime, ceftriaxone, cefoperazone) and tetracyclines - 36.3% of resistant strains. Microbiological monitoring in patients with VAT over a 10-year period revealed a trend towards the prevalence of gram-negative microflora inoculation, and over the past two years, the range of isolated multi-resistant flora has been expanding.