Yet monitoring the efficacy of a cleaning and disinfection programme is like fighting an invisible enemy. And even having established the presence of micro-organisms, it may also be important to distinguish between pathogenic or non-pathogenic, specific (eg. Salmonella enteritidis), non-specific (eg. E. Coli) or disease-causing bacteria, viruses, fungi or mycoplasma.

Three options for effectively monitoring hatchery hygiene

1. Visual inspection

Regularly take a critical look at levels of cleanliness throughout the hatchery and its equipment. Use a checklist, on which dirty spots can be indicated and recorded. Pay special attention to hard-to-reach areas, like backside cooling coils, door rubbers, ventilation pipes and the suction heads of the transfer machine. When dirt is visible to the naked eye, there will certainly be many micro-organisms present.

2. Agar cultures for non-specific bacteria

Make the enemy visible using a non-specific bacteria count. When compared with a reference (see example, table 1), this will illustrate the efficacy of your cleaning and disinfection programme. Remember that pathogenic bacteria and other micro-organisms are likely to co-exist alongside non-specific bacteria, and some fungi can also be revealed by this procedure.

Methods for inspecting flat surfaces (e.g. walls, ceilings) include:

• Swab and streak procedure: rub a sterile swab, moistened in a sterile solution or a manufactured sterile culturette, over a 2.5-5.0 cm area of sample surface. Gently streak the used swab over the surface of an agar plate several times, in a zig-zag fashion.
• Rodac plate procedure: Rodac plates are pre-filled with agar gel, which is slightly higher than the edge of the plate, so that direct contact can be made with the surface to be sampled. Remove the cover of the plate, press the agar gently onto the surface to be monitored (do not move the plate while contact is made), then replace the cover, taking care not to touch the agar.

Whether you use swabs or Rodac plates:

• Keep one agar plate unopened as a "negative sample", to test the sterility of the plates and act as a 'control'.
• Clearly mark where each sample was collected on the outside base of each plate. Predefine the number of samples per room - and test a variety of locations within each room/area (e.g. door handle, candling table, hatching egg).
• Store collected samples and your 'negative' sample upside down at 37ºC-37.5ºC in a laboratory incubator or setter, taking care to place the plates in a plastic bag and set them down where they will not be disturbed. Agar contains nutrients that bacteria thrive upon. A single bacterium - and to a lesser extent, a fungal spore - will multiply under these conditions, to become visible as a colony.

After 24-48 hours, count and record the cultures. The number of colonies present indicates the hygienic state of the surface sampled. The evaluation of these counts should be based on the hatchery's own criteria, or by the terms of a national or integration-wide quality programme.

3. Specific bacterial and fungal monitoring

To test for particular bacteria and fungi, specific plates contain a selective agar, formulated specifically to encourage growth or colonisation by the bacterium/fungi being investigated. Fluff, chick paper and other hatchery materials may also be prepared for monitoring in this way.

For specific monitoring, it is often advisable to contact a specialised laboratory for sampling and/or an accurate interpretation of results.

Advice

To fully benefit from this type of monitoring programme, the results should be discussed with staff responsible for cleaning and disinfection and/or with your supplier of detergents and disinfectants. Depending on results, you may need to change procedures and/or consider a change of the cleaning and disinfection products being used.

It is good practice to maintain records of all results, so that any changes occurring over time can be observed in the different areas monitored. It is also recommended that results are carefully compared with hatchability and liveability data.

Table 1: evaluation of bacterial counts according to Dutch standards (1999 Poultry Farming Hygiene Regulations).
Colonies/Plate	Score	Average hatchery score	Rating
No colonies	0	0.0-0.5	Excellent
1-40	1	0.6-1.0	Good
41-120	2	1.1-1.5	Reasonable
121-400	3	1.6-2.0	Moderate
> 400	4	2.1-2.5	Bad
Uncountable	5	> 2.6	Very bad

Based on Rodac plates with a diameter of 5,5 cm; Number of samples and locations are specified.

May 2008