Quantifying within-household transmission of extended-spectrum β-lactamase-producing bacteria.
OBJECTIVE
Patients can acquire extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae during hospitalization, and colonized patients may transmit these bacteria after discharge, most likely to household contacts. In this study, ESBL transmission was quantified in households.


METHODS
Faecal samples were longitudinally collected from hospitalized patients colonized with ESBL-producing bacteria and from their household members during hospitalization of the index patient and at 3, 6, 12 and 18 months. A mathematical household model was developed, which allowed for person-to-person transmission, acquisition from other sources (background transmission), and losing carriage. Next, a deterministic population model with a household structure was created, informed by parameter values found in the household model.


RESULTS
In all, 74 index patients and 84 household members were included. In more than half of the household members ESBL-producing bacteria were demonstrated at some time during follow up. Person-to-person transmission occurred at a rate of 0.0053/colonized person/day (0.0025-0.011), background transmission at 0.00015/day (95% CI 0.00002-0.00039), and decolonization at 0.0026/day (0.0016-0.0040) for index patients and 0.0090/day (0.0046-0.018) for household members. The estimated probability of transmission from an index patient to a household contact was 67% and 37% vice versa.


CONCLUSIONS
There is frequent transmission of ESBL-producing bacteria in households, which may contribute to the observed endemicity of ESBL carriage in the Netherlands. However, the population model suggests that there is not a single dominant acquisition route in the community.
Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, The Netherlands. Electronic address: m.r.haverkate-2@umcutrecht.nl.
M R
MR
Haverkate
Department of Medical Microbiology, University Medical Centre Utrecht, Utrecht, The Netherlands; SALTRO, Department of Medical Microbiology, Utrecht, The Netherlands.
T N
TN
Platteel
Department of Medical Microbiology, University Medical Centre Utrecht, Utrecht, The Netherlands.
A C
AC
Fluit
Department of Medical Microbiology, Medisch Centrum Alkmaar, Alkmaar, The Netherlands.
J W
JW
Cohen Stuart
Department of Medical Microbiology, Bronovo Hospital, den Haag, The Netherlands; Department of Medical Microbiology, Alrijne Hospital, Leiden, The Netherlands.
M A
MA
Leverstein-van Hall
Department of Medical Microbiology, Diakonessenhuis, Utrecht, The Netherlands.
S F T
SFT
Thijsen
Department of Medical Microbiology, University Medical Centre Utrecht, Utrecht, The Netherlands.
J
J
Scharringa
Department of Medical Microbiology, University Medical Centre Utrecht, Utrecht, The Netherlands.
R C
RC
Kloosterman
Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, The Netherlands; Department of Medical Microbiology, University Medical Centre Utrecht, Utrecht, The Netherlands.
M J M
MJM
Bonten
Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Utrecht, The Netherlands; Department of Mathematics, Utrecht University, Utrecht, The Netherlands.
M C J
MCJ
Bootsma
D000328:Adult; D002353:Carrier State; D002675:Child, Preschool; D016358:Contact Tracing / Q000379:methods*; D004755:Enterobacteriaceae / Q000201:enzymology*; D004756:Enterobacteriaceae Infections / Q000382:microbiology* / Q000635:transmission*; D005191:Family Characteristics; D005260:Female; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D001618:beta-Lactamases / Q000378:metabolism*
D001618:beta-Lactamases
Colonisation; Enterobacteriaceae; Extended-spectrum beta-lactamase (ESBL); Mathematical model; Within-household transmission