Antibiotic Selective Treatment System based on quarter level Petrifilm™ results at dry-off

From research project : Selective Dry-off Treatment based on quarter level using on-farm diagnosis.
Jean-Philippe Roy (Principal investigator, UMontréal), Fidèle Kabera (Ph.D. candidate, UMontréal),
Greg Keefe (collaborator, UPEI) and Simon Dufour (collaborator, UMontréal)

Herd Selection Criteria

• SCC < 250,000 cells/ml in bulk tank milk

Cow Selection Criteria
  • Dry-off duration: 45 – 75 days
  • Currently pregnant and in good shape
  • No antimicrobial treatment during the last 14 days before dry-off
The day before drying off, collect a sterile sample of milk per quarter
Milk culture per quarter on a Petrifilm AC
  • Petrifilm identification for each quartier

  • Dilution 1:10 of the quarter milk sample

  • Petrifilm inoculation for each quarter

Petrifilm Interpretation
  • 0 – 4 colonies : non-infected quarter

  • 5 colonies : infected quarter

Apply dry-off treatment to quarter accordingly to Petrifilm results
  • 0 – 4 colonies : use internal teat sealant only in that quarter

  • 5 colonies : use antibiotic treatment and internal teat sealant in that quarter

MATERIALS
R

Ink marker

R

Applicator

R

Syringes 3ml, 10ml and 1 1/2 in. needles

R

Petrifilm AC plates

R

Sterile Water Bottle

R

Disposable gloves

R

Incubator

R

Sterile sample vials

R

70% alcohol soaked gauze pad

NOTES
$

Repeat the same steps for the four quarters of the cow (a Petrifilm plate for each quarter).

$

INOCULATE EACH PETRIFILMTM PLATE AND SPREAD THE SAMPLE ON CIRCULAR AREA BEFORE GOING NEXT

$

SAMPLING, DILUTION AND INOCULATION MUST BE MADE WITH PRECAUTION AND STERILITY

  • Do not touch the inside of the tube and the cap with the syringe or fingers or remove the cap on the table when handling.
  • Change the syringe and needle for each quarter.
  • Disinfect the cap of the sterile water bottle each time the sample is taken.
  • After opening, write the date on the bottle and keep it in the fridge for a maximum of one month.

Petrifilm AC inoculation protocole

(Test for the counting of the total aerobic flora)

Step 1

Take 9 ml of sterile water and put in a sterile tube. Do not touch the inside of the tube and cap with the syringe or fingers.

Step 2

Take 1 ml of the milk sample.

Step 3

Put 1 ml of milk in a tube containing 9 ml of sterile water (dilution 1:10).

Step 4

Homogenize: Close the tube and shake the diluted milk tube by flipping it up and down at least 5 times.

Etape 5 Prélever 1 ml de lait dilué à l’aide de la seringue utilisée précédemment. Aspirer et remettre le lait dilué une fois, afin de rincer la seringue.

Step 5

Take 1 ml of diluted milk using the syringe used previously. Aspirate and return the diluted milk once, to rinse the syringe.

Step 6

Place the previously identified Petrifilm plate (cow, quarter, date and time) on a flat surface, lift the top film, then place 1 ml of diluted milk in the center of the lower film without touching it with the syringe or fingers.

Step 7

Release the top film. Place the applicator over the top film (circular side down) and lightly apply pressure to spread the sample over the circular area.
Image credits: 3M

Step 8

Put the Petrifilm in the incubator at 35 °C (95 °F) for 24 hours. Make sure it contains some water to maintain a slight humidity.

Step 9

Read the results on the Petrifilm. Each point represents a bacterial colony. Count the entire plate, not just a square. Record the results in your files.

 

Réseau canadien de recherche sur la mammite bovine et la qualité du lait (RCRMBQL)

The Mastitis Network brings together numerous Canadian and international researchers, students and other professionals around an ambitious research program. The purpose of this program is to offer the Canadian dairy industry new tools and knowledge to improve udder health, milk quality and to reduce the important economic losses caused by mastitis.

To contact the administrative team click here

Location:
Faculté de médecine vétérinaire, Université de Montréal
3200,  Sicotte street, Saint-Hyacinthe (Quebec) J2S 2M2 CANADA

Tel. : (450) 773-8521 ext.8619 |   Site internet: www.mastitisnetwork.org

 

Contact us

9 + 11 =