Imported Klebsiella pneumoniae carbapenemase-producing K. pneumoniae clones in a Greek hospital: impact of infection control measures for restraining their dissemination

Abstract

The recent emergence of carbapenemase-producing Enterobacteriaceae strains represents a major threat for hospitalized patients. We document the dissemination and control of carbapenemase-producing Klebsiella pneumoniae clones in a Greek hospital. During a 3-year study period (January 2009 to December 2011), carbapenemase-producing K. pneumoniae strains were isolated from clinical samples from 73 individual patients. Phenotyping and molecular testing confirmed that 52 patients were infected with K. pneumoniae carbapenemase 2 (KPC-2) producers, 12 were infected with VIM-1 producers, and the remaining 9 were infected with isolates producing both KPC-2 and VIM-1 enzymes. Twenty-eight of these clinical cases were characterized as imported health care associated, and 23 of these were attributed to KPC producers and 5 were attributed to KPC and VIM producers. The remaining 45 cases were deemed hospital acquired. In the second year of the study, intensified infection control intervention was implemented, followed by active surveillance and carrier isolation in the third year. The incidence of carbapenemase-producing K. pneumoniae patient cases decreased from 0.52/1,000 patient days in 2009 to 0.32/1,000 patient days in 2010 (P = 0.075). Following these additional infection control measures, the incidence fell to 0.21/1,000 patient days in 2011 and differed significantly from that in 2009 (P = 0.0028). Despite the fact that the imported cases of carbapenemase-producing K. pneumoniae were equally distributed over this 3-year period, the incidence of hospital-acquired cases decreased from 0.36/1,000 patient days in 2009 to 0.19/1,000 patient days in 2010 (P = 0.058) and to 0.1/1,000 patient days in 2011 (P = 0.0012). Our findings suggest that rigorous infection control measures and active surveillance can effectively reduce the incidence of secondary transmission due to KPC-producing pathogens.

Fig 1

Distribution of new clinical cases due to carbapenemase-producing K. pneumoniae in the ICU and medical and surgical wards.

Fig 2

PFGE clonal types and subtypes detected among carbapenemase-producing K. pneumoniae isolates. Lanes 1 to 11, 15, 20, and 21, representative isolates from KPC-producing K. pneumoniae clinical cases; lanes 12 to 14 and 16 to 18, representative isolates from KPC- and VIM-producing K. pneumonia clinical cases; lane 19, KPC- and VIM-producing K. pneumoniae environmental isolate; lanes M, molecular size markers.

Fig 3

Incidence of new clinical cases due to carbapenemase-producing K. pneumoniae per 1,000 patient days per quarter during the 3 years of this study. Arrows a and b indicate the starting points of the additional infection control intervention measures undertaken in January 2010 and January 2011, respectively.