Microbiology, appropriateness of empiric antibiotics and clinical outcome of hospital-acquired pneumonia in the era of multidrug-resistant Acinetobacter baumannii

Backgrounds: The choice of empiric antibiotic therapy should be based on knowledge of the prevailing pathogens, susceptibility patterns, and individual patient risk factors for multidrug resistance. Methods: The admitted patients with hospital-acquired pneumonia via ICD-10 from Jan. 1st, 2019 to Dec. 31st, 2019 in Hallym University Chuncheon Sacred Heart Hospital were searched. Appropriate therapy was considered present if all pathogens in the initial culture were sensitive to the empiric antibiotics. Results: Of 155 patients with hospital-acquired pneumonia, 60% were male and the mean age was 69.6±13.5. 73 (47.1%) were treated at the Intensive care unit and 60 (38.7%) were mechanically ventilated. Steroid and proton pump inhibitors were administered to 29.7%, and 65.8% of patients respectively. Hospital and ICU stays were 39.7±45.4, 14±23.1 respectively. Days with mechanical ventilation were 5.8±13.6. The predominant pathogens isolated in the first episode of pneumonia were Gram-negative bacilli (81.7 percent): Acinetobacter baumannii 32 (22 were multidrug-resistant), Klebsiella pneumoniae 17, Pseudomonas spp. 11 (6 were MDR). E. coli 8, Sternotrophomonas maltophilia 6, carbapenem-resistant Enterobacteriaceae 3. etc. Gram-positive bacilli were 9: methicillin-resistant Staphylococcus aureus 6, methicillin-resistant coagulase-negative Staphylococcus 3. Clinical success was 124 (80%) and mortality was 35 (22.6%). The proportion of Inappropriate therapy was 37 (41.6%). Conclusions: MDR-Acinetobacter baumannii was the prevailing pathogen that caused the inappropriateness of empiric antibiotic therapy.