Background
Pseudomonas aeruginosa pneumonia is commonly treated with systemic antibiotics to ensure adequate treatment of multidrug resistant (MDR) bacteria. However, intravenous (IV) antibiotics often achieve suboptimal pulmonary concentrations. We therefore aimed to evaluate the effect of inhaled amikacin (AMK) plus IV meropenem (MEM) on bactericidal efficacy in a swine model of monolateral MDR P. aeruginosa pneumonia.
Methods
We ventilated 18 pigs with monolateral MDR P. aeruginosa pneumonia for up to 102 h. At 24 h after the bacterial challenge, the animals were randomized to receive 72 h of treatment with either inhaled saline (control), IV MEM only, or IV-MEM plus inhaled AMK (MEM + AMK). We dosed IV MEM at 25 mg/kg every 8 h and inhaled AMK at 400 mg every 12 h. The primary outcomes were the P. aeruginosa burden and histopathological injury in lung tissue. Secondary outcomes included the P. aeruginosa burden in tracheal secretions and bronchoalveolar lavage fluid, the development of antibiotic resistance, the antibiotic distribution, and the levels of inflammatory markers.
Results
The median (25–75th percentile) P. aeruginosa lung burden for animals in the control, MEM only, and MEM + AMK groups was 2.91 (1.75–5.69), 0.72 (0.12–3.35), and 0.90 (0–4.55) log10 CFU/g (p = 0.009). Inhaled therapy had no effect on preventing dissemination compared to systemic monotherapy, but it did have significantly higher bactericidal efficacy in tracheal secretions only. Remarkably, the minimum inhibitory concentration of MEM increased to > 32 mg/L after 72-h exposure to monotherapy in 83% of animals, while the addition of AMK prevented this increase (p = 0.037). Adjunctive therapy also slightly affected interleukin-1β downregulation. Despite finding high AMK concentrations in pulmonary samples, we found no paired differences in the epithelial lining fluid concentration between infected and non-infected lungs. Finally, a non-significant trend was observed for higher amikacin penetration in low-affected lung areas.
Conclusions
In a swine model of monolateral MDR P. aeruginosa pneumonia, resistant to the inhaled AMK and susceptible to the IV antibiotic, the use of AMK as an adjuvant treatment offered no benefits for either the colonization of pulmonary tissue or the prevention of pathogen dissemination. However, inhaled AMK improved bacterial eradication in the proximal airways and hindered antibiotic resistance.
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. carbon dioxide 30 [27][28][29][30][31][32][33][34][35] mmHg and median temperature 37.1 [36.8-37.3]°C. After removal of artefacts, the mean monitoring time was 22 h08 (8 h54). All patients had impaired cerebral autoregulation during their monitoring time. The mean IAR index was 17 (9.5) %. During H 0 H 6 and H 18 H 24 , the majority of our patients; respectively 53 and 71 % had an IAR index > 10 %. Conclusion According to our data, patients with septic shock had impaired cerebral autoregulation within the first 24 hours of their admission in the ICU. In our patients, we described a variability of distribution of impaired autoregulation according to time.
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