On-farm milk culture training workshop Christina Petersson-Wolfe Department of Dairy Science Virginia Tech
The right drug for the right bug Different bugs respond to different treatments Antibiotic sensitivities previously relied on Culture based therapy is best option
Waiting 24 hr to treat? No difference in long-term outcomes Recurrence Milk production Risk for culling SCS Reduced antimicrobial usage by 50% No change in cure rates
On-farm culture Various culture systems marketed Minnesota Bi-Plate and Tri-Plate most widely used User guides printed in both English and Spanish Low initial input cost Incubator = $55 Hova-Bator (egg incubator) Supplies = ~$2-3 per sample
On-farm culture Three different selective medias Factor agar (proprietary ingredients) G+ only MTKT agar Streptococcus spp. only MacConkey agar G- only
On-farm culture Aseptically collect sample from clinical quarter Use sterile cotton swab to streak on all 3 medias dipping back in sample between Incubate overnight and observe growth at 24 h Determine treatment
Plating on Tri-plates 1. Factor Agar (Bright red) 3. MacConkey Agar (light pink) 2. Modified TKT (Dark red) 1. Mix milk samples by inverting several times 2. Using aseptic technique uncap the tube of milk 3. Take a clean loop or swab and dip it into the tube 4. Starting with Factor Agar, streak milk sample from outside-in following streak lines shown above 5. Repeat steps 1-3 and streak on Modified TKT agar 6. Repeat steps 1-3 and streak on MacConkey Agar 7. Cap milk sample and discard loop/swab 8. Incubate milk sample for 24 h at 37C
On-farm culture Gram positive growth = treatment Can determine Strep from other G+ and treat differently if vet recommended < Gram neg growth = no treatment > Gram neg growth = systemic treatment
On-farm culture Strep spp. possible Staph spp. + + +
On-farm culture Identifying Staph aureus Factor agar + Staph aureus
Factor Agar (red) Gram pos growth Staph/Strep On-farm culture results Streak in order of: Bright red (Factor Agar) Dark red (MTKT) Light pink (MacConkey) MTKT (Dark red) Grows Strep only MacConkey (pink) Gram neg growth E. coli/klebsiella Result + + - Strep or mixed Staph/Strep + - - Staph (check hemolysis) - + - Strep - - + Gram-negative (E. coli, Klebsiella, etc ) + + + Contaminated
CNS versus Staph aureus Tri-plate alone doesn t give you a definitive answer Check hemolysis patterns Can do coagulase test if wanted Pos (+) = Staph aureus Neg (-) = CNS
About the bugs Classification Bacteria Source Control Staph CNS & Staph. hyicus Skin flora, subclinical Post dip, DCT Staph. aureus Infected udders Segregation, milking hygiene, treatment, cull
About the bugs Classification Bacteria Source Control Strep Env. strep & Environment Pre & post dip Enterococcus DCT and clean environment Strep. dys. Environment and infected udders Pre & post dip DCT and clean environment
About the bugs Classification Bacteria Source Control Coliform E. coli Bedding, manure, soil Sand, clean & dry, pre dip, J5 Klebsiella Organic bedding Avoid sawdust & recycled manure, clean & dry Enterobacter Bedding, manure, soil Sand, clean & dry, pre dip, J5 Serratia Soil and plants Sand, clean & dry, pre dip, J5, no chlorhex. dip
How to treat Classification Bacteria Treatment Staph CNS & Staph hyicus Tx clinicals Today Don t tx subclin unless SCC DCT Staph. aureus Early lactation heifers 5-7d Pirsue Tx 2 nd, 3 rd lactation first time cases Chronics unresponsive Occasional cure with DCT Cull chronics when feasible Culture fresh cows to monitor and tx
Why are they hard to treat?
How to treat Classification Bacteria Treatment Strep Env. strep. & Enterococcus 4-5 d penicillin - (3.5cc/100 lbs BW systemically) Good cure with DCT Strep. dys. Label treatment with Today Good cure with DCT
How to treat Classification Bacteria Treatment Coliform E. coli Local: No IMM treatment, Klebsiella supportive therapy if necessary, infection typically clears in < 10 days Enterobacter Systemic: IV Fluids (2-3L saline), followed with oral, Banamine (20cc on sick big Holsteins), 60-80 cc Oxytet IV Serratia Resistant to antibiotics, chronic infections, often result in cull 180-300 ml hypertonic saline infused may help Extra label use - Spectinomycin
Residues Follow label directions Treatment regiment Withholding time Test for antibiotic residue
Contact me Want more info? milk@vt.edu or 540-231-4767
2015 Conference Sponsors Platinum Multimin USA Zoetis Gold Elanco Maryland-Virginia Producers Cooperative Association Silver CPC Commodities Kentucky Dairy Development Council Contributor Bluegrass Dairy and Food, Inc. DFA Mid-East DFA Southeast W.D. Hoard & Sons Thank you for your support!