Superinfection associated with prolonged antibiotic use in non-ventilator associated hospital-acquired pneumonia

Background Non-ventilator associated hospital-acquired pneumonia accounts for significant antibiotic use and is associated with a high rate of resistance emergence. However, the optimal duration of antibiotic treatment is uncertain, especially in cases of non-fermenting gram-negative bacilli. Objective To compare a short course (5-7 days) to a prolonged course (10-14 days) of antibiotics for non-ventilator associated hospital-acquired pneumonia. Methods Data collected retrospectively on patients completed treatment in a Malaysian tertiary hospital from January 2017 till December 2018. Regression analysis determined variables independently associated with clinical outcome. Main outcome measures Clinical resolution, superinfection, 30-day and 90-day all-cause mortality between short and prolonged courses. Results Of the 167 patients included, 112 patients were treated with a short course antibiotic, whereas 55 patients received a prolonged course of therapy. Neither short nor prolonged course group has a significantly higher rate of clinical resolution. Short course group had significantly higher mean +/- SD antibiotic-free days (21.9 +/- 3.5 versus 15.1 +/- 6.2 days, p < 0.001). Higher rate of superinfection was observed in prolonged course group compared to short course group (6.3% versus 18.2%, p = 0.027). For non-ventilator associated hospital-acquired pneumonia caused by non-fermenting gram-negative bacilli, the superinfection rate was higher in prolonged course group (35.7% versus 15.4%, p = 0.385) while 30-day mortality rate was higher in the short course group (38.5% versus 14.3%, p = 0.209). Non-fermenting gram-negative bacilli cause higher rate of superinfection (p = 0.010). Conclusion We found no clinical benefit as defined by clinical resolution and reduction in all-cause mortality in prolonging antimicrobial therapy. Superinfections emerge more frequently in prolonged course of antibiotic therapy and more likely to develop in non-fermenting gram-negative bacilli.