Risk factors and outcomes for the acquisition of carbapenem-resistant Gram-negative bacillus bacteremia: A retrospective propensity-matched case control study

Abstract

Background/purpose: A substantial number of carbapenem-resistant Gram-negative bacilli (CR GNB) have been identified among the etiologic multidrug-resistant GNB in healthcare-associated infections. For achieving a better therapeutic outcome by minimizing inappropriate empirical antibiotic treatment before blood culture and susceptibility testing results are available, it is very important to identify patients who are at risk for the development of CR GNB bacteremia. Methods: Retrospective analysis of propensity-score matched (PSM) adult patients with CR GNB bacteremia (PSM-group 1 [n = 95]) and those with non-CR GNB bacteremia (PSM-group 2 [n = 190]). Results: PSM-group 1 was found to a significantly longer length of hospital stay (27 vs. 18 days; p < 0.001) after emerging GNB bacteremia and a higher 30-day all-cause mortality rate (27.4% vs. 5.8%; p < 0.001), when compared with PSM-2 group. Independent risk factors for the acquisition of CR GNB bacteremia were previous exposure to an antipseudomonal penicillin (odds ratio [OR] = 3.58; 95% confidence interval [CI] = 1.30–9.90), an antipseudomonal cephalosporin (OR = 3.49; 95% CI = 1.09–11.24), and a carbapenem (OR = 3.60; 95% CI = 1.37–9.47), and longer length of hospital stay before the development of GNB bacteremia (OR = 1.03; 95% CI = 1.01–1.05). Conclusion: Risk factors for acquisition of CR GNB bacteremia identified in this study each may serve as a reminder alerting clinicians to hospitalized patients at risk for CR GNB bacteremia requiring appropriate antibiotic coverage, and in these circumstances, combined antibiotics may be used until antimicrobial de-escalation/adjustment is clearly indicated by the subsequently identified pathogenic GNB and its susceptibility profile. Keywords: Risk factors, Outcomes, Carbapenem-resistant, Gram-negative bacillus, Bacteremia, Propensity-matched