Presentation on theme: "Chemical disinfectants commonly used in the poultry sector and their impact on Salmonella – an outline of methods and results Kim O. Gradel Danish Veterinary."— Presentation transcript:
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 Resistance against disinfectants Minimum inhibitory concentration (MIC) tests Adaptation and de-adaptation tests Conclusions Surface disinfection tests Materials and methods Results Conclusions General conclusions
Chemical tests related to general disinfection factors Micro- organism DisinfectantSurroundings Type State/condition Organic matter Temperature pH Biofilm Type Concentration Resistance to disinfectants Surface disinfection tests
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.
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.
Resistance against disinfectants: persistently Salmonella-infected broiler houses
Salmonella serotype Number of crops with the same Salmonella type > 30 Enteritidis Typhimurium Tennessee :b: Infantis Indiana Resistance against disinfectants: persistence in broiler houses In this study, 67 and 21 broiler houses were represented with two or more than two isolates, respectively.
Resistance against disinfectants: persistently Salmonella-infected broiler houses First isolate selected Middle isolate selected Last isolate selected
Resistance against disinfectants: sources of bacterial isolates
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
Resistance against disinfectants: MIC-tests
Resistance against disinfectants: adaptation and de-adaptation MIC-tests
Resistance to disinfectants: MIC-tests (Salmonella results)
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.
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.
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.
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 o C, respectively. Disinfection time: 5, 15, 30 minutes.
Surface disinfection tests: design 1. High bacterial concentrations in organic matter. 2. Organic matter added to poultry house materials hours of drying. 4. Disinfection for set time periods hours of drying. 6. Traditional bacteriological procedures with tenfold dilutions, i.e. a most probable number ( semi- quantitative ) method.
Surface disinfection tests: concrete flag with feed
Surface disinfection tests. feed chain links with feed
Surface disinfection tests: disinfection of concrete flags
esults for concrete flags Surface disinfection tests: results for concrete flags CfuGpfTBTADT S. EnteritidisS. Senftenberg ForG/BOksWaForG/BOksWa L L ND0002 L L L H H
Surface disinfection tests: results for feed chain links OMTBTADT S. EnteritidisS. SenftenbergEnterococcus faecalis ForG/BOksWaForG/BOksWaForG/BOksWa FA FE
Surface disinfection tests: results for wooden dowels OMTBTADT S. EnteritidisS. SenftenbergEnterococcus faecalis ForG/BOksWaForG/BOksWaForG/BOksWa FA > FE
Surface disinfection tests: results for jute egg belts cfuTBTADT S. EnteritidisS. SenftenbergEnterococcus faecalis ForG/BOksWaForG/BOksWaForG/BOksWa L L L H H H
Surface disinfection tests: conclusions I Efficacy (best first): formalin > glutaraldehyde/benzalkonium chloride > oxidising compound > water. Except: Feed chain links with fats at 30 o C before and after disinfection, where the oxidising compound apparently was the most effective. Formalin is better than glutaraldehyde/benzalkonium chloride at 6 o C, although it is often stated that formalin is only effective above 16 o C, whereas glutaraldehyde is effective down to 5 o C!
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.
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.
Acknowledgments Kirsten Holm, DVI, Å rhus, Denmark. Luke Randall, Weybridge, UK. Ian McLaren, Weybridge, UK.