Clinical and Bacteriological Characteristics of IMP-Type Metallo-β-Lactamase-Producing Pseudomonas aeruginosa

Abstract

IMP-type metallo-β-lactamase-producing bacteria have recently emerged worldwide. We conducted a case-control study in which 69 inpatients harboring bla_IMP-positive Pseudomonas aeruginosa and 247 control subjects with bla_IMP-negative pathogens were investigated. Prolonged hospitalization, antineoplastic chemotherapy, corticosteroid therapy (P =.001), and indwelling urinary catheters (P =.04) were risk factors for isolation of bla_IMP-positive pathogens. The predominant source was urine (P =.001). The duration of antibiotic treatment and the total dose (including of carbapenems) were significantly greater among case patients than among control subjects (P <.01). bla_IMP-positive P. aeruginosa isolates were more frequently resistant to multiple drugs (P =.001) and caused more infections (P =.001) than bla_IMP-negative pathogens. There were no significant differences in bacteriological outcome (P =.94); however, infection-related death was more frequent among case patients than among control subjects (P =.023). These results suggest that precautionary measures against the spread of bla_IMP-positive isolates are needed, because, for most of such pathogens, no antibiotic is potent enough to be used as a single agent in treatment of infection.