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.