Thompson, Hailey

Background Chlorhexidine is commonly used in prevention bundles for ventilator-associated pneumonia. Results for use of chlorhexidine in critically ill patients requiring mechanical ventilation via an endotracheal tube are mixed, and data for patients using a tracheostomy are lacking. Objectives To assess the risk for ventilator-associated pneumonia according to chlorhexidine exposure in patients requiring a new tracheostomy for mechanical ventilation. Methods This single-center, retrospective cohort study compared the development of ventilator-associated pneumonia according to chlorhexidine exposure in adult intensive care unit patients requiring new tracheostomy at a large academic medical center. Adults who received a new tracheostomy and required ventilator support for at least 48 hours were included. Patients treated for pneumonia at the time of tracheostomy or who met additional exclusion criteria were excluded. Results Of 235 patients who met the inclusion criteria, 203 received chlorhexidine and 32 did not. The cohort was predominantly White, male, and admitted to a surgical intensive care unit. Incidence of ventilator-associated pneumonia did not differ significantly between patients exposed or not to chlorhexidine (by 30 days, 32.5% vs 35.7%, P = .87). Time to development of ventilator-associated pneumonia also did not differ significantly between patients exposed or not (9 vs 12 days, respectively, P = .34). Conclusions Chlorhexidine exposure was not associated with a difference in the incidence of or time to ventilator-associated pneumonia after new tracheostomy. Further study is needed on the role of chlorhexidine in preventing ventilator-associated pneumonia after a new tracheostomy.

Abstract Background Small colony variants (SCVs) of Staphylococcus aureus (SA) have significant intracellular persistence. Fluoroquinolones demonstrate intracellular activity and are often utilized to treat SCVs. Delafloxacin is a fluroquinolone with increased potency at a low pH, which could lead to enhanced intracellular activity. This study evaluates delafloxacin activity against intracellular MSSA and MSRA SCV isolates.Figure 1.Illustration of SCV co-culture methods Methods Six clinical SCV-SA isolates were co-cultured with human macrophages for 1 hour, allowing for phagocytosis (Fig 1). The remaining extracellular bacteria were removed and antibiotic treatments of delafloxacin, levofloxacin, gentamicin, cefazolin, or vancomycin were added. After 5-hour and 24-hour incubation periods, supernatants were collected for extracellular colony forming unit (CFU) enumeration. Macrophages were washed, lysed, collected, and plated for intracellular bacterial CFU enumeration. All conditions were repeated in triplicate and compared using a Mann Whitney U test.Figure 2.Intracellular SCV-MSSA CFUs Results Delafloxacin resulted in a 1.9-log reduction in intracellular CFUs (p< 0.001) at 5 hours and a 3.4 log reduction (p< 0.001) at 24 hours compared to antibiotic-free control for MSSA strains (Fig 2). Similarly, levofloxacin resulted in a 1.6-log (p< 0.001) and 1.9-log (p< 0.001) reduction in CFUs after 5 and 24 hours, respectively. Delafloxacin was more effective at clearing intracellular bacteria than levofloxacin at 24 hours (p= 0.004). In MRSA-SCV isolates, delafloxacin demonstrated CFU reduction of 2.4-log (p< 0.001) at 5 hours and 4.7-log (p< 0.001) at 24 hours compared to antibiotic-free control (Fig 3). Levofloxacin demonstrated a 1.6-log (p< 0.001) reduction at 5 hours and 1.5-log (p= 0.034) reduction at 24 hours. In comparison to levofloxacin, delafloxacin led to greater reductions in MRSA CFUs at both 5 hours and 24 hours of incubation, 0.85-log (p= 0.028) and 3.2-log (p< 0.001) respectively.Figure 3.Intracellular SCV-MRSA CFUs Conclusion The results demonstrate delafloxacin having greater intracellular activity than levofloxacin and other comparator antibiotics against both MSSA and MRSA SCVs. These results support using delafloxacin to treat recurrent or chronic infections caused by either MSSA or MRSA SCVs and suggest that the observed efficacy may be a result of enhanced intracellular activity. Disclosures All Authors: No reported disclosures