Making mastitis treatment decisions using laboratory culture diagnosis

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Making mastitis treatment decisions using
laboratory culture diagnosis
Utilisation de lanalyse bactériologique de lait
pour le traitement des mammites

• Philip Sears, DVM, PhD
• Department of Large Animal Clinical Science
• College of Veterinary Medicine - Michigan State
  University
• East Lansing, Michigan USA

Merci de cette invitation de parler ici par
Société Française de Buiatrie
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Clinical Mastitis Definition

• Score 1 Mild (signs milk)
• abnormal milk
• Score 2 Moderate (signs milk gland)
• abnormal milk
• swelling, pain
• Score 3 Severe (signs milk, gland cow)
• abnormal milk
• swelling, pain
• systemic fever, dehydration shock

Sears, 2001
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Clinical Predictive Schemefor Gram-negative
Mastitis

• White, et al Jones Ward Morin, et al
• watery milk watery milk watery milk
• swollen gland summer summer
• fever fever ? milk protein
• weakness gt10 dim ? rumen sounds
• clear/white milk old cow
• no abscesses
• previous mastitis

watery milk more common in Strep mastitis than
coliform mastitis - Obritzhauser et al, 1995
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Clinical Predictive Schemefor Gram-negative
Mastitis

• 3 experienced practitioners correctly predicted
  21/36 (58) culture results
• 4 less experienced practitioners correctly
  predicted 39/82 (48) culture results
• For coliform mastitis
• Sens .64, Spec .64
• PPV .51, NPV .76 (prevalence 31)

White et al, 1986
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Clinical Predictive Schemefor Gram-negative
Mastitis
Factor Sensitivity Specificity Summer -
mastitis .51 .65 Watery milk .18 .89 Rumen
contraction lt3/2min .27 .85 Summer and
rumen .08 .95 Watery milk rumen .02 .96 Fin
al model .58 .80
Morin, 1998
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Milk Cultures

• Clinical quarters or cows
• Herd analysis
• all cows
• HSCC cows
• monitoring herd
• bulk tank milk

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Milk Culture
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Milk Culturessample consideration

• Cow samples
• composite sampling for herd survey
• quarter sampling - clinical cases, high SCC
• Bulk tank samples
• screen herd for contagious pathogens
• monitor herds for Strep ag S. aureus

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Milk Sampling
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Determine EtiologyBacteriologic

• False Negatives
• clinical case caused by coliforms
• cyclic shedding of S. aureus
• Mycoplasma - require selective media
• after antibiotic therapy
• composite sample (quarter sample)
• reduce FN by multiple samples (consecutive
  samples)

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Determine EtiologyBacteriologic

• False Positive
• environmental bacterial isolates
• False Positive are less likely when
• isolation of Strep ag Staph aureus
• single pathogen culture (Strep, Staph, coliform)
• multiply culture from the same quarter
• 2-3 consecutive samples

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Milk Cultures

• Infection level in herd
• Type of infections
• Source of infections
• Control and Prevention

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Milk Cultures
1. Select cows for culture (herd, HSCC, etc) 2.
Collect an aseptic milk sample 3. Collect
composite or quarter milk sample 4. Refrigrate
(or ice) sample at collection
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Culture milk on blood agar plates or selective
media.
Cultivez le lait sur lagar de sang ou les médias
sélectifs
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Mastitis Problem Solving
Step 1 Identify possible mastitis problems.
(review records
)
Subclinical
mastitis
Clinical mastitis
Severe clinical cases
DHIA - SCC
New clinical cases
Bulk tank SCC
gt1 per year
gt15 with LSgt4.5
gt2 per month
gt250,000 cell/ml
Step 2 Use diagnostic test to determine
causative organisms
.

Bacteriological Cultures

(milk)
Contagious organisms
Environmental organisms
(usually
subclinical
)
(usually clinical)
Coliforms
Strep
sp
Strep ag
Staph
sp
Staph aureus
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Selective Media - Bi-plates
1
2
3
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Coliforms
Coliformes
Gram-negative rods KOH negative Large grey
colonies mosit or mucoid
Klebsiella sp
E. coli
Tiges Gram-négative Négative de KOH Grandes
colonies grises moite ou mucoïde
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esculin reaction
CAMP Test
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Staphylococci
Staphylocoques
Staph aureus
Staph sp
Gram-positive cocci KOH negative Opaque
colonies white to yellow colonies
Couques Gram-positifs Positif de KOH Colonies
opaques Blanc pour jaunir des colonies
Staph aureus

? ?
-
Staph sp
Staph sp
Coagulase Test
Staphylococcus aureus
Double zone hemolysis
Coagulate plasma
(? - ?)
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Clinical Mastitis Pathogen Isolation
Sears, 2003
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Clinical Mastitis Treatment Protocol
Remove cow
Quarter loss to
production
Cull
Return to Herd
Milk
Hess 2003
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20 Tx
80 NT
Hess 2003
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CONCLUSION
E. coli and no growth did not benefit from
antibiotic treatment for salable milk and
clinical signs. Culture identified no growth and
Coliforms rapidly (24 hrs). Treatment delay
reduced antibiotic treatment 80. Treatment
delay did not effect clinical outcome for
Gram-positive bacteria (Strep Staph, 20 of
cases). Change in treatment protocol did not
jeopardize the animals health or well-being.
Hess 2003
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Treatment Decisions
Dans un article récent qui emploie un modèle
clinique de mastite, le traite-ment antibiotique
n'est pas profitable. Le coût d'écart de lait au
loin-repose le gain dans la production.
(Bennedsgaard, 2003) Cependant, ces modèles
placent tous les microbes pathogènes ensemble et
n'identifient pas la mastite de staphylo-coque et
de streptocoque qui peut répondre favorable à la
thérapie antibiotique.
(Wilson, 1996)
In a recent article that uses a clinical mastitis
model, antibiotic treatment is not profitable.
The cost of milk discard off-sets the gain in
production. (Bennedsgaard,
2003) However, these models place all pathogens
together and do not separate out Staph and Strep
mastitis that can respond favorably to antibiotic
therapy. (Wilson, 1996)
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CLINICAL MASTITIS PROTOCOL
Submit aseptically
collected milk sample
Moderate Cases
Severe Cases
Mild Cases
milk abnormal
milk abnormal
milk abnormal
udder abnormal
udder abnormal
udder normal
cow normal
cow abnormal
cow normal
Day 1 fluids, systemic
Day 1

no therapy, re-evaluate
antibiotics, anti-inflammatory,
Day 1

no therapy
severity within 6-8 hours
calcium as needed
Day 2 re-evaluate severity
Day 2 re-evaluate severity
Day 2 re-evaluate severity
continue treatment as needed
IMM treatment based on
IMM treatment based on
IMM treatment based on
presumptive culture
presumptive culture
presumptive culture
Culture
other
Other
Streptococcus
Yeast or
Staphylococcus
Mild E. coli
Severe E. coli
Klebsiella sp
No Growth
Streptococci
Gram-negative
agalactiae
Mycoplasma
aureus
Approved intramammary therapy
No intramammary
Approved intramammary antibiotic
unlikely to be effective consider
treatment
therapy
systemic or extra-label antibiotic
therapy
Roberson J, Vet Clinic N Am 2003
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Summary

• Culturing cows with subclinical infections can
  aid in the develop-ment of mastitis treatment
  protocols and mastitis prevention plans.
• Culturing clinical cases can be useful in
  identifying cases responsive to antibiotic
  therapy and reducing antibiotic residues without
  jeopardizing animal health.

• La cultivation des vaches avec des infections
  de subcliniques peut faciliter le développement
  des protocoles de traitement de mastite et des
  plans d'empêchement de mastite.
• La cultivation des cas cliniques peut être
  utile en identifiant des cas sensibles à la
  thérapie antibiotique et en réduisant les résidus
  antibiotiques sans compromettre la santé des
  animaux.

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Thank You Merci