Outbreak ofKlebsiella pneumoniaeCarbapenemase–ProducingCitrobacter freundiiat a Tertiary Acute Care Facility in Miami, Florida

Abstract

OBJECTIVE To describe the investigation and control of a rare cluster of Klebsiella pneumoniae carbapenemase-producing Citrobacter freundii in a hospital in southern Florida. METHODS An epidemiologic investigation, review of infection prevention procedures, and molecular studies including whole genome sequencing were conducted. RESULTS An outbreak of K. pneumoniae carbapenemase-3-producing C. freundii was identified at a tertiary hospital in Florida in 2014. Of the 6 cases identified, 3 occurred in the same intensive care unit and were caused by the same clone. For 2 of the 3 remaining cases, the isolates had low carbapenem minimum inhibitory concentrations and were unrelated by whole genome sequencing. As a response to the outbreak, supplementary environmental cleaning was implemented, including closure and terminal cleaning of the unit where the 3 cases clustered, in addition to the infection control bundle already in place at the time. No further cases were identified after these additional interventions. CONCLUSIONS Although C. freundii is not a species that commonly demonstrates carbapenem resistance, our findings suggest that carbapenemase-producing C. freundii may be underdetected even when active surveillance is in place and has a potential to cause hospital outbreak. Infect Control Hosp Epidemiol 2017;38:320-326.

Clinical and Genomic Epidemiology of Carbapenem-Nonsusceptible Citrobacter spp. at a Tertiary Health Care Center over 2 Decades

“…Among them, carbapenem-nonsusceptible Citrobacter spp. (CNSC) have become increasingly recognized as health care-associated pathogens ( 9 – 13 ). CNSC isolates have been found to be both genotypically and phenotypically diverse ( 14 , 15 ), and their resistance to carbapenems is frequently caused by plasmid-borne carbapenemase genes, which can be readily acquired through horizontal gene transfer ( 12 , 16 ).…”

Carbapenem-resistant Citrobacter spp. isolated in Spain from 2013 to 2015 produced a variety of carbapenemases including VIM-1, OXA-48, KPC-2, NDM-1 and VIM-2

“…; very few studies have reported C. freundii producing VIM or KPC. [4][5][6][7][8] Some Enterobacteriaceae species, such as Citrobacter spp. J Antimicrob Chemother 2017; 72: 3283-3287 doi:10.1093/jac/dkx325 Advance Access publication 27 September 2017 or Enterobacter spp., often present decreased susceptibility to carbapenems, mainly ertapenem, due to the overproduction of chromosomal AmpC b-lactamase plus reduced outer membrane permeability; 9 as a consequence, production of carbapenemases in these species may be underdiagnosed in clinical microbiology laboratories.…”

Clinical and genomic epidemiology of carbapenem-non-susceptibleCitrobacterspp. at a tertiary healthcare center over two decades

“…Citrobacter spp. have become increasing recognized as a cause of multidrug-resistant healthcare-associated infections around the world (10, 42–44), and prior reports have identified CNSC predominantly from healthcare sources and often associated with nosocomial outbreaks (9, 12, 45). We detected a significant increase in the proportion of Citrobacter spp.…”

“…Among them, carbapenem-non-susceptible Citrobacter spp. (CNSC) have become increasingly recognized as a healthcare-associated pathogen (9–13). CNSC isolates have been found to be both genotypically and phenotypically diverse (14, 15), and their resistance to carbapenems is frequently caused by plasmid-encoded carbapenemases, which can be readily acquired through horizontal gene transfer (12, 16).…”

“…Information regarding the clinical epidemiology, genetic diversity, and mechanisms of carbapenem resistance among CNSC in the United States are currently limited to a small number of studies and very few isolates (9, 17–19). Here we aimed to investigate the emergence of CNSC within our healthcare system using epidemiology and genomics approaches.…”