Transmission dynamics of extended-spectrum β-lactamase-producing Enterobacteriaceae in the tertiary care hospital and the household setting.
BACKGROUND
Studies about transmission rates of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in hospitals and households are scarce.


METHODS
Eighty-two index patients with new carriage of ESBL-producing Escherichia coli (ESBL-Ec; n = 72) or ESBL-producing Klebsiella pneumoniae (ESBL-Kp; n = 10) and their hospital (n = 112) and household (n = 96) contacts were studied prospectively from May 2008 through September 2010. Isolates were phenotypically and molecularly characterized (sequencing of bla genes, repetitive extragenic palindromic polymerase chain reaction, pulse-field gel electrophoresis, and multilocus sequence typing). Transmission was defined as carriage of a clonally-related ESBL producer with identical bla(ESBL) gene(s) in the index patient and his or her contact(s).


RESULTS
CTX-M-15 was the most prevalent ESBL in ESBL-Ec (58%) and ESBL-Kp (70%) in the index patients. Twenty (28%) ESBL-Ec isolates were of the hyperepidemic clone ST131. In the hospital, transmission rates were 4.5% (ESBL-Ec) and 8.3% (ESBL-Kp) and the incidences of transmissions were 5.6 (Ec) and 13.9 (Kp) per 1000 exposure days, respectively. Incidence of ESBL-Kp hospital transmission was significantly higher than that of ESBL-Ec (P < .0001), despite implementation of infection control measures in 75% of ESBL-Kp index patients but only 22% of ESBL-Ec index patients. Detection of ESBL producers not linked to an index patient was as frequent (ESBL-Ec, 5.7%; ESBL-Kp, 16.7%) as nosocomial transmission events. In households, transmission rates were 23% for ESBL-Ec and 25% for ESBL-Kp.


CONCLUSIONS
Household outweighs nosocomial transmission of ESBL producers. The effect of hospital infection control measures may differ between different species and clones of ESBL producers.
Institute for Infectious Diseases, University of Bern, Switzerland.
Markus
M
Hilty
Belinda Y
BY
Betsch
Katja
K
Bögli-Stuber
Nadja
N
Heiniger
Markus
M
Stadler
Marianne
M
Küffer
Andreas
A
Kronenberg
Christine
C
Rohrer
Suzanne
S
Aebi
Andrea
A
Endimiani
Sara
S
Droz
Kathrin
K
Mühlemann
D000293:Adolescent; D000328:Adult; D015373:Bacterial Typing Techniques; D002353:Carrier State / Q000382:microbiology / Q000635:transmission*; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology / Q000635:transmission*; D005191:Family Characteristics; D005260:Female; D005838:Genotype; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology / Q000635:transmission*; D007711:Klebsiella pneumoniae / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D010641:Phenotype; D011446:Prospective Studies; D062606:Tertiary Care Centers; D055815:Young Adult; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
D001618:beta-Lactamases