mastitis epidemiology epidemiology and pathogenesis: paradigm … · 2013. 5. 27. · 1 nkvet, 2013...

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NKVet, 2013 - © RN Zadoks

Epidemiology and

Pathogenesis: Paradigm

Shifts in the Molecular Era

Ruth Zadoks

Moredun Research Institute

University of Glasgow


Mastitis Epidemiology

Contagious mastitis:

5-Point Plan

Environmental mastitis:

Pressure vs. Resistance


Mastitis Pathobiology

Host adapted

“Knows how to behave”

Opportunistic

“Does not know how to behave”

Reduce incidence:

prevention

Reduce duration:

treatment, culling


Pathobiology ↔ Epidemiology

• Host level affects population level

• Host or niche adaptation or ecotype

Zadoks, CAB Reviews 2007;2:030e


Species and Strains

Zadoks and Schukken, Vet Clin North Am 2006;22:229 NKVet, 2013 - © RN Zadoks

Comparative Typing

• Based on comparison of fragment length polymorphisms

or “banding patterns”

• Standardization problematic – scope of studies limited

• “Quick and dirty” vs. “cheap and cheerful”

• Only strain typing method used for diagnostics (RAPD)

PF

GE

RA

PD

http://en.wikipedia.org/wiki/File:New_Glasgow_Crest.png

2


Definitive Typing

• Based on DNA sequence data – A, C, G and T

• Standardization easy – web based infrastructure

• World wide comparison across studies

• “Slow and expensive” vs. “value for money”

• In diagnostic use in human medicine

Gen

om

es

ML

ST

Richards et al., Infect Genet Evol. 2011;11:1263


Strain Heterogeneity

Klebsiella from soil Strep. uberis from soil

L 80 81 82 89 88 64 65 67 68 79 69 70 71 72 52 53 54 62 L

KPKVRPKO

L 80 81 82 89 88 64 65 67 68 79 69 70 71 72 52 53 54 62 L

KPKVRPKO

L 80 81 82 89 88 64 65 67 68 79 69 70 71 72 52 53 54 62 L

KPKVRPKO

Many different strains in the environment

Many different strains present in environmental mastitis cases


Strain Homogeneity



Molecular Clockspeed and

Spatio-temporal Scale

Struelens et al., Inf Control Hospital Epidemiol. 998;19:565


Applications and Insights

• Pathobiology in animals

– Transient and persistent infections (RAPD, PFGE)

– Host adaptation and response to treatment (MLST)

• Introduction of pathogens into herds

– Animals (PFGE)

– Other sources (MLST)

• Transmission in herds

– Contagious (RAPD)

– Environmental (RAPD)

– Point source (RAPD)

– Host-to-host (whole genome sequencing)

http://www.chicagostamps.com/rrtroot/articles/cattlearticle.htmlhttp://www.google.co.uk/imgres?imgurl=http://image.shutterstock.com/display_pic_with_logo/299839/299839,1274098507,8/stock-photo-vietnam-circa-a-stamp-printed-in-vietnam-shows-a-young-goat-series-devoted-to-pet-circa-53257390.jpg&imgrefurl=http://www.shutterstock.com/pic-53257390/stock-photo-vietnam-circa-a-stamp-printed-in-vietnam-shows-a-young-goat-series-devoted-to-pet-circa.html&usg=__nYCKolOqIS3ZOmfHTXegg5GuBYk=&h=470&w=362&sz=91&hl=en&start=5&zoom=1&um=1&itbs=1&tbnid=VEJmH111vIbSrM:&tbnh=129&tbnw=99&prev=/images?q=stamp+collection+goat&um=1&hl=en&rls=com.microsoft:en-gb:IE-SearchBox&rlz=1I7GGLH&tbs=isch:1

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Transient E. coli Infections

• Each cow has her own strain of E. coli

• Many different strains are present on a single farm

• Multiple infections due to a single strain are unlikely

Schukken et al., J Dairy Sci. 2011;94:6203


Repeated Clinical Mastitis

• Scenario 1 – Cow becomes infected, CM

– Cow clears infection

– Cows become infected, CM

– Cow clears infection

– Etc.

• Failure of prevention

• Multiple infections,

multiple strains

• Scenario 2 – Cow becomes infected, CM

– Clinical signs disappear

– Clinical signs recur, CM

– Clinical signs disappear

– Etc.

• Failure of cure

• Single infection,

single strain

In the milking parlour, the clinical appearance is the same


Persistent E. coli Infections

Döpfer et al., J Dairy Sci. 1999;82:80 Bradley et al., J Dairy Sci.2000;83:1957


Pathobiology and Treatment

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Study

% b

ac

teri

olo

gic

al c

ure

N

N N

N

E

E

E

S

S S S

S

C

C

N No treatment

S 2-3 day subclinical C 2-3 day clinical

E Extended therapy Host-adapted

Strep. uberis

Opportunistic

Strep. uberis

Zadoks, CAB Reviews 2007;2:030e


Pathobiology and Treatment

• Dutch field trial on subclinical S. aureus mastitis – 166 isolates, 139 quarters, 119 cows, 31 herds

– treatment and control groups

• Hypothesis: host-adaptation predicts cure – niche-adapted (CC50, CC97, CC151, CC497): low cure

– non-adapted (all others): high cure

• Literature: penicillin-resistance predicts cure – resistant: low cure (even with other antibiotics)

– non-resistant: high cure

• Result: host adaptation does NOT predict cure

Barkema et al., J. Dairy Sci. 2006;89:1877 Van den Borne et al., J. Dairy Sci. 2010;93:2550


S. aureus - Probability of Cure

Theory

• Bovine ↓

• Non-bovine ↑

• Resistant ↓

• Non-resistant ↑

Practice?

• NB-NR: low SCC, excl.

• B-R: high SCC, culled

• NB-R, B-NR: present

Resistant Non-

resistant

Bovine ↓↓ ↓↑

Non-bovine ↑↓ ↑↑

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Introduction – Cattle

• One-year study with 4 samplings in 15 herds

• More animals purchased, more strains introduced

• May apply to expanding herds in Nordic countries

Category Herds Total New

Closed herds 6 3 1

Contract reared replacement heifers 4 9 4

Purchased lactating cows 2 7 5

Purchased replacement heifers 3 15 10

S. aureus strainsMiddleton et al., Epidemiol Infect. 2002;129:387


Introduction – Niche adaptation

Bisharat et al., J Clin Microbiol. 2004;42:2161 Delannoy et al., BMC Microbiol. 2013;13:41

ST67


Introduction - Humans

S. agalactiae in Denmark:

strains (MLST)

S. agalactiae in Denmark:

prevalence

Katholm, Veterinärkongressen 2010 Zadoks et al., J Mammary Gland Biol Neoplasia 2011;16(4):357-72


Transmission

A

A

A

C

D

B


S. aureus - Contagious

Juhasz et al., Emerging Inf Dis. 2007;13:630 Zadoks and Schukken, Vet Clin North Am. 2006;22:229

I - ST151


S. aureus - Environmental

Schukken et al., submitted

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• Multiple strains in lactating cows

• Different strains in pre-calving heifers – not milked yet

• Transient, severe (heifer) or mild (cow) clinical mastitis

• Not controlled by 5-point plan

L 1 2 3 4 5 6 7 8 9 10 11 + L

Schukken et al., submitted



Gu

rja

r e

t a

l., V

et C

lin N

ort

h A

m

20

12

;28:5

65

Sommerhauser et al., Vet Microbiol. 2003;96:91


S. uberis - Environmental

• S. uberis is common in dry cows and heifers

• The 5-point plan does not eliminate S. uberis mastitis

Baseggio et al., Mol Cell Probes 1997;11:349 Wang et al., Epidemiol Infect.1999;123:317


S. uberis - Contagious

• One strain affecting multiple lactating cows

• Spread via liners of milking machine demonstrated

• PMTD and treatment/segregation of infected animals

• Ignore the 5-point plan at your peril!

L 1 2 3 4 5 6 7 8 9 10 11 12 13 14 L

+ + - W


A

A

A

C

D

BA

A

A

C

D

B

Contagious or Point Source?

?


Klebsiella mastitis

• One strain in most cows

• Contagious or point source

• Isolated from liners

Multiple strains

• Isolated from bedding

One dominant strain

L Milk + - w L

Munoz et al., J Clin Microbiol. 2007;45:3964

Position Position

time time

LF RF LF RF

LR RR LR RR

LF RF 1100 LF RF 174 Kleb. events

LR RR LR RR (Index) * LR 4/2

LF RF LF RF 28m * RR 4/15

LR RR LR RR

37t 40t

LF RF 1068 LF RF

LR RR LR RR

LF RF LF RF

LR RR 23m LR RR

LF RF 842 41t 44t LF RF 1028

31t LR RR LR RR

LF RF 21m 24m LF RF

LR RR LR RR

29t 32t 48t

Cow

9 right 7 right

Cow

6


"Contagious via the Environment"


MRSA transmission - PFGE

• 1978 - MRSA mastitis in

dairy cattle in Belgium -

milkers thought to be the

source (Devriese, 1978)

• 2007 - MRSA mastitis in

dairy cattle in Hungary -

milker and cattle share

same strain

Mastitis outbreak

isolates

Human

isolate

Juhasz et al., Emerging Inf Dis. 2007;13:630


MRSA - MLST

• Host-association of CCs

• Major human CCs

• Major bovine CCs

– CC97

– CC151

– CC479

• MRSA in cattle and milker: ST1

–

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Lessons for Management

Low High

Low Environmental Environmental

Hig

h

Environmental ContagiousDu

rati

on

Transmission risk


Conclusion and Outlook

• Pathogens, knowledge and management evolves –

paradigms (and veterinarians) also need to evolve

• Gram positive and Gram negative species can cause

chronic infections

• Gram positive and Gram negative species can cause

contagious mastitis

• Contagious or environmental epidemiology is determined

by pathogen species, strain and herd management

• Whole genome sequencing, microbiomics and

metagenomics will generate additional insights into

mastitis pathobiology and epidemiology

mastitis epidemiology epidemiology and pathogenesis: paradigm … · 2013. 5. 27. · 1 nkvet, 2013...

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