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Chemical disinfectants commonly used in the poultry sector and their impact on Salmonella – an outline of methods and

Chemical disinfectants commonly used in the poultry sector and their impact on Salmonella – an outline of methods and results . Kim O. Gradel Danish Veterinary Institute, Å rhus, Denmark SYMPOSIUM: DISINFECTION IN ANIMAL PRODUCTION Tuesday 18 November, 2003, Aarhus, Denmark. Disposition.

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Chemical disinfectants commonly used in the poultry sector and their impact on Salmonella – an outline of methods and

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  1. Chemical disinfectants commonly used in the poultry sector and their impact on Salmonella– an outline of methods and results Kim O. Gradel Danish Veterinary Institute, Århus, Denmark SYMPOSIUM: DISINFECTION IN ANIMAL PRODUCTION Tuesday 18 November, 2003, Aarhus, Denmark

  2. Disposition • Resistance against disinfectants • Minimum inhibitory concentration (MIC) tests • Adaptation and de-adaptation tests • Conclusions • Surface disinfection tests • Materials and methods • Results • Conclusions • General conclusions

  3. Micro- organism Type ”State/condition” Disinfectant Surroundings Type Concentration Organic matter Temperature pH Biofilm Chemical tests related to general disinfection factors Resistance to disinfectants Surface disinfection tests

  4. Resistance against disinfectants • Hypothesis: There is an association between persistence of Salmonella in poultry houses and the common use of a few types of disinfectants in these. • Aims: • To see if minimum inhibitory concentrations (MICs) against five commonly used disinfectants could be related to Salmonella persistence or use of disinfectants in Danish broiler houses. • To see if resistance against the five disinfectants could be introduced and maintained in the laboratory.

  5. Resistance against disinfectants:epidemiological tools Since 1992, for all Danish broiler flocks/crop cycles: • samples for Salmonella have been submitted. • The use of disinfectants has been registered by a veterinarian visiting the flock. • All data have been registered in a central database.

  6. Resistance against disinfectants:persistently Salmonella-infected broiler houses

  7. Salmonella serotypeNumber of crops with the same Salmonella type123456-1011-2021-30> 30Enteritidis51642Typhimurium2743122Tennessee441124.12:b:-132246451Infantis923364Indiana112113Resistance against disinfectants:persistence in broiler houses • In this study, 67 and 21 broiler houses were represented • with two or more than two isolates, respectively.

  8. Resistance against disinfectants:persistently Salmonella-infected broiler houses First isolate selected ”Middle” isolate selected Last isolate selected

  9. Resistance against disinfectants:sources of bacterial isolates

  10. Resistance against disinfectants:disinfectants used in the study • Formaldehyde (24.5%) • Glutaraldehyde (23%) and benzalkonium chloride (5%) compound (Bio Komplet Plus) • Oxidising compound (blend of peroxygen compounds) (Virkon S) • Phenol (30-45% high boiling tar acids) (FFS) • Iodophor (FAM 30) ”Danish” disinfectants ”English” disinfectants

  11. Resistance against disinfectants:MIC-tests

  12. Resistance against disinfectants:adaptation and de-adaptation MIC-tests MIC-tests

  13. Resistance to disinfectants:MIC-tests (Salmonella results)

  14. Resistance to disinfectnats:Changes in MICs during the persistence period • 67 broiler houses represented with two isolates. • 21 broiler houses represented with more than two isolates. • Generally, no significant changes (p = 0.30). • Oxidising compound has relatively most increases, but • p = 0.10.

  15. Resistance to disinfectants:more results (data not shown) • No associations between MICs and use of disinfectants • in the preceding download period. • Adaptation or de-adaptation did not alter any MICs • beyond one doubling dilution, i.e. within normal • biological variation.

  16. Resistance to disinfectants:conclusions • Resistance to commonly used disinfectants • does not play a major role in persistence • of Salmonella in Danish broiler houses. • In the laboratory, it was not possible to adapt • selected strains to the actual disinfectants.

  17. Surface disinfection tests • Principles: • Worst-case scenario surface disinfection tests simulating conditions and disinfection procedures encountered in badly cleaned poultry houses, especially at low temperatures. • Factors: • Isolates: S. Enteritidis (low MICs), S. Senftenberg (high MICs), Enterococcus faecalis (putative indicator bacterium). • Poultry house materials: Concrete flags, rusty feed chain links, wooden dowels, jute egg belts. • Organic matter: Feed, fats, egg yolk. • Disinfectants: formalin, glutaraldehyde/benzalkomium chloride, oxidising compound, water (control). • Temperatures before and after disinfection: 6/11/20/30 and 6/11/30 oC, respectively. • Disinfection time: 5, 15, 30 minutes.

  18. Surface disinfection tests:design • High bacterial concentrations in organic matter. • Organic matter ”added to” poultry house materials. • 24 hours of drying. • Disinfection for set time periods. • 25 hours of drying. • Traditional bacteriological procedures with tenfold dilutions, i.e. a most probable number (”semi-quantitative”) method.

  19. Surface disinfection tests:concrete flag with feed

  20. Surface disinfection tests.feed chain links with feed

  21. Surface disinfection tests: disinfection of concrete flags

  22. Surface disinfection tests:results for concrete flags

  23. Surface disinfection tests: results for feed chain links

  24. Surface disinfection tests:results for wooden dowels

  25. Surface disinfection tests:results for jute egg belts

  26. Surface disinfection tests: conclusions I • Efficacy (best first): formalin > glutaraldehyde/benzalkonium chloride > oxidising compound > water. • Except: Feed chain links with fats at 30 oC before and after disinfection, where the oxidising compound apparently was the most effective. • Formalin is better than glutaraldehyde/benzalkonium chloride at 6 oC, although it is often stated that formalin is only effective above 16 oC, whereas glutaraldehyde is effective down to 5 oC!

  27. Surface disinfection tests: conclusions II • For the effective disinfectants (formalin and glutaraldehyde/benzalkonium chloride) there were no differences between the two Salmonella isolates, whereas S. Senftenberg was more susceptible than S. Enteritidis in tests with the oxidising compound and water, in spite of higher MICs for S. Senftenberg (for formalin and the oxidising compound). • In general, Enterococcus faecalis was more recalcitrant than the two Salmonella isolates, i.e. it is a putative indicator bacterium, e.g. in field trials. • Fats seem to be the best protectant for the bacteria among the types of organic matter used. • In general, there were few differences between the different poultry house materials.

  28. General conclusions • For Salmonella, resistance to commonly used disinfectants does not seem to be an important aspect of persistence. • Results from unrealistic tests are difficult to extrapolate to realistic tests. • For Salmonella and other vegetative bacteria, results indicate that the surroundings are more important for the efficacy of disinfection than the type of bacteria.

  29. Acknowledgments • Kirsten Holm, DVI, Århus, Denmark. • Luke Randall, Weybridge, UK. • Ian McLaren, Weybridge, UK.

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