Microsoft powerpoint - p51poster tom timmerman

Department of Reproduction, Obstetrics, and Herd Health Faculty of Veterinary Medicine, Ghent University RISK FACTORS ASSOCIATED WITH TETRACYCLINE RESISTANCE IN
LACTOSE-POSITIVE ENTERIC COLIFORMS FROM FATTENING PIGS
Timmerman T., Dewulf J., Catry B., Duchateau L., de Kruif A., Maes D.
Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
Introduction
To date, only a few studies evaluating the effects of various husbandry conditions on the development and
persistence of antibiotic-resistant bacteria in swine have been reported. The majority of these studies are single
factor analyses, focusing on one (or two) possible risk factor(s) like age (Langlois et al., 1988; Mathew et al.,
1999), housing conditions (Langlois et al., 1988), transport or overcrowding (Molitoris et al., 1987; Langlois and
Dawson, 1999),… . These studies indicate that, besides exposure to antibiotics, also other factors can influence
antimicrobial resistance. The aim of this study was to to assess the impact of different management and housing
conditions on the degree of tetracycline-resistance (TETR) in lactose-positive enteric coliforms (LPEC)
associated with fattening pigs kept under commercial farming conditions.
Materials and Methods
Fifty randomly selected pig
Study population on farm:
Registation of
Weaners (10 ± 2 weeks)
(a) General herd data
closed or semi-closed
Growers (18 ± 2 weeks)
(b) Antimicrobial drug consumption
located in the most
(c) Finishers (26 ± 2 weeks)
(c) Management factors
Statistical analysis:
dense pig areas
(d) Housing factors
Multivariable linear
at least 150 sows and
mixed effects model
600 fattening pigs
with herd as random
Collection of pooled faecal
Determination of TETR in LPEC per
samples per production stage
pooled sample using an agar
(4 pens, 4 pigs per pen)
dilution technique
Results and Discussion
The overall TETR in LPEC was 56.8% (min. 8.2%, median 56.9%, max. 100.0%; 95% CI 53.2%-60.4%). Results of
the univariable and multivariable analyses are shown in Table 1. The multivariable analysis identified tetracycline
treatment and inside pen hygiene as significant risk factors.
Table 1: Estimated herd-level TETR and 95% CIs from analyses based on the linear mixed model with herd as random factor.
Only parameters which were significant in the univariable analysis and which were not correlated (r<0.60) are shown.
Parameter
P-value univariable
P-value multivariable
Production system
56.4-65.3
Continuous
44.1-56.2
Moving to other pen/room
<3 days ago
52.7-92.6
3-10days ago
46.2-75.6
>10days ago
51.7-59.5
Inside pen hygiene
48.7-57.4
59.5-71.8
Tetracycline treatment
59.3-71.0
48.5-71.0
Conclusions
• Antimicrobial treatment is the most important risk factor in the development of tetracycline resistance.
• Pigs housed in dirty pens had a lower TETR than pigs housed in clean pens. This is probably caused be intake
of susceptible bacteria from the environment which dilute or replace the resistant LPEC.
• Changes in antimicrobial resistance after transport and holding stress in swine have been reported (Langlois
et al., 1984; Molitoris et al., 1987). Similar univariable effects were seen after moving pigs to another pen/room,
but could not be confirmed in the multivariable analysis.
• In the univariable analysis, animals in a continuous production system have a lower TETR. A possible
explanation is that these animals take up susceptible bacteria, originating from older or non-treated animals,
which dilute or replace the resistant LPEC.
This study was supported by IWT-Flanders, grant number SB/23200.
UNIVERSITY

Source: http://www.svepm.org.uk/posters/2005/Risk%20factors%20associated%20with%20tetracycline%20resistance%20in%20lactose%20positive%20enteric%20coliforms%20from%20fattening%20pigs.pdf