Clinical characteristics and risk factors for mortality in Morganella morganii bacteremia

Background and Purpose: To clarify the clinical characteristics and risk factors for mortality of patients with Morganella morganii bacteremia. Methods: Retrospective analyses were undertaken of patients with M. morganii bacteremia treated at Chang Gung Memorial Hospital-Kaohsiung, between 2002 and 2003. Results: Seventy three patients (39 male, 34 female; mean age, 64.43 ± 16.58 years) were included for analyses. At least 1 underlying disease was found in 91.7% of patients. Solid tumors (34.2%) was most frequently encountered. The leading portals of entry of M. morganii bacteremia were the urinary tract (37%) and hepatobiliary tract (22%). Of all included cases, 69.9% were community-acquired and 45.2% were of polymicrobial bacteremia. Urinary tract (47.5%) and hepatobiliary tract (30.3%) were the major portals of entry among patients with monomicrobial and polymicrobial M. morganii bacteremia, respectively. The overall mortality rate was 38.3%. Susceptibility testing of M. morganii isolates showed universal resistance to cephalothin, and high resistance rates to cefuroxime (90.5%) and amoxicillin-clavulanate (95.9%). In contrast to 95.8% of the M. morganii isolates being ceftazidime-susceptible, 19.4% were imipenem-resistant. Univariate analyses showed that fatal cases had significantly higher rates of diabetes mellitus (50% vs 20%, p=0.010), polymicrobial bacteremia (64.2% vs 33.3%, p=0.015) and inappropriate antibiotic treatment (67.8% vs 26.6%, p=0.001). Multivariate analysis indicated that inappropriate antibiotic treatment (odds ratio, 4.8, p=0.002) was the only independent risk factor for mortality. Conclusions: M. morganii bacteremia frequently occurred secondary to urinary tract or hepatobiliary tract infection, and was associated with a high mortality rate, especially for those not receiving appropriate antibiotic therapy.