Prospective observational study of Klebsiella bacteremia in 230 patients: outcome for antibiotic combinations versus monotherapy.

Combination antimicrobial agent therapy has been advocated for treatment of gram-negative bacteremia, including that caused by Klebsiella spp. We performed a prospective, observational, 10-hospital collaborative study to evaluate the efficacy of antibiotic combination therapy versus that of monotherapy for 230 consecutive patients with Klebsiella bacteremia. The species involved were K. pneumoniae (82%), K. oxytoca (15%), and K. ozaenae (0.4%). Of the bacteremias, 26% were polymicrobial in nature. A total of 53% of cases were nosocomial infections. The most common portals were the urinary tract (28%), biliary tract (12%), lung (10%), and abdomen (9%). Some 49 and 51% of the patients had received monotherapy and antibiotic combination therapy (beta-lactam plus aminoglycoside), respectively; 14-day mortalities in the two groups were 20 and 18%, respectively. However, for the subgroup of patients who experienced hypotension within 72 h prior to or on the day of the positive blood culture, those patients who received combination therapy experienced significantly lower mortality (24%) than did those who received monotherapy (50%). We conclude that monotherapy with an antibiotic that is active in vitro against Klebsiella (beta-lactam or aminoglycoside) is sufficient therapy for less severely ill patients (immunocompetent, urinary tract portal, mentally alert, normal vital signs). On the other hand, for severely ill patients who experience hypotension, antibiotic combination therapy with a beta-lactam and an aminoglycoside agent is preferred.