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First Case Phil’s Friendly Filly: Philena

Quarter horse

One-year-old

Owner’s complaint: Yucky yellow-green

stuff running out if its nose…………. (aka nasal discharge)

Not eating well

Acting “sick”

Philena the Philly

Physical exam: Fever

Nasal discharge

Swelling behind the mandible: right side

Tip: This is abnormal 24 hour BAP culture

Some Help?

Gram’s stain of exudate

What’s Your Diagnosis? Diagnosis? (disease common name)

A. Strangles

B. Lymphadenitis

C. Mastitis

D. Runny nose

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What is the cause?

A. Streptococcus suis

B. Streptococcus agalactiae

C. Streptococcus equi

D. None of the above

What is the most probable source of the infection?

A. Soil

B. Feed

C. Normal bacterial flora in the nose

D. Another infected horse

Which of the following are important to the pathogenesis?

A. M protein on Strep. equi

B. Age of the horse

C. Acute inflammatory response: PMNs

D. Localization in regional lymph nodes

E. All of the above

Source = infected horse; another foal or adult carrierExposure history, e.g.. horse showHost immunologically vulnerable; age / naïveCritical time between end of passive immunity and beginning of active immunity

Inhalation or ingestion: infection starts at tonsilsInvasion – inflammation (PMN) – dissemination S. equi factors:resists phagocytosis: M proteinkills phagocytes: leukotoxinimpairs host attempt to wall off: fibrinolysinDNAase: thin runny pus

Source = infected horse; another foal or adult carrierExposure history, e.g.. horse showHost immunologically vulnerable; age / naïveCritical time between end of passive immunity and beginning of active immunity

Inhalation or ingestion: infection starts at tonsilsInvasion – inflammation (PMN) – dissemination S. equi factors:resists phagocytosis: M proteinkills phagocytes: leukotoxinimpairs host attempt to wall off: fibrinolysinDNAase: thin runny pus

Key Elements of the Story

More Key Story Elements

Swelling = pain, abscessation = dead PMNs

Dissemination = bastard strangles

Antibiotic resistance not a problem: penicillin

To treat or not to treat………THAT is the question

Diagnosis by culture

Prevention by vaccination

Lymph node infection – more inflammation

Swelling = pain, abscessation = dead PMNs

Dissemination = bastard strangles

Antibiotic resistance not a problem: penicillin

To treat or not to treat………THAT is the question

Diagnosis by culture

Prevention by vaccination

Lymph node infection – more inflammation

Human version of the story

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What if The Foal Was Vaccinated?

Strep equi vaccine

IM

2 doses

2 weeks apart

Vaccines Sometime Fail..why?

Dratt!

Vaccines Sometime Fail..why?

D ose; too low, not often enough or inactive (dashboard)

R oute; antibodies not at site of infection

A gent wrong; by genus, species or strain (antigenic type)what else causes strangles?

A ge; too young or too old

T iming; too soon before challenge or too long ago

T ype; killed – shorter immunity, live – longer immunity

Next Case

Marvin’s MistakeI expanded my herd by 200 cows last month. Now I’ve got some serious cases of mastitis.

Millie's Mammary

Holstein

4 years-old

Ten days post-calving

One quarter hot and inflamed

Don’t you DARE touch me!

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Milk abnormal -High somatic cell count (SCC)

Clotted, stringy, cellular

Additional information

BAP at 24 hours

Gram stain

CAMP Test

Strep unknown

Staph. aureus (dbl zone)

Synergistic hemolysis

What’s Your Diagnosis?

MastitisStreptococcus agalactiae

(a Group B Streptococcus)

What was the primary source of infection?

A. Infected purchased cattle

B. Skin of the milker’s hands

C. Cow’s environment

D. Normal microflora of the udder

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Source = infected cowOBLIGATE pathogenCan be eradicated from herd

Prevention by pre-purchase testingSpreads at milking - - HYGIENEAscending infectionAcute inflammation; neutrophilsAntibiotic resistance not a problemDiagnosis: culture, cow or bulk tankCAMP test = definitive

Source = infected cowOBLIGATE pathogenCan be eradicated from herd

Prevention by pre-purchase testingSpreads at milking - - HYGIENEAscending infectionAcute inflammation; neutrophilsAntibiotic resistance not a problemDiagnosis: culture, cow or bulk tankCAMP test = definitive

Key Elements of the Story Culture, treat, and follow-up when eradicating Strep ag

1. Culture ALL cows – not just high SCC.

2. Use commercial intramammary drugs. Use aseptic good technique when treating

3. Recheck all treated cows 10 days later.

4. Cull cows that did not cure.

What is an SCC?How do you measure the SCC?What is an SCC?How do you measure the SCC?

Mastitis Measures SCC = somatic (animal) cell

count; primarily inflammatory cells (PMNs) most common measure of milk quality; farmers paid a premium for milk with lower SCC.

DHI labs –automated cell counters.

Cow-side – CMTCalifornia Mastitis Test rough estimate of SCC.

SPC = Standard Plate Count; counts of bacteria

Clumping = positive: grade 0, 1, 2Clumping = positive: grade 0, 1, 2

SCC: How High is Too High?

High quality milk has SCC < 200,000/ml

Strep ag in a large herdFour important lessons………

1. Use a reliable lab close to home.

2. Culture all cows early.3. Culture again shortly

after treatment.4. It is possible to culture

thousands of cows and eliminate the problem.

From Pharmacia & Upjohn excerpted From Dairy Health Solutions.

Don’t Buy ProblemsJim Dickrell, Dairy Today, October 1999.

Herd A – bought 110 cows no mastitis screening: Cost of mastitis* = $48,131

Herd B – bought 450 cows cultured all cows first: Cost of prevention = $7,485

* Due to Strep agPrevention Pays !!!Prevention Pays !!!

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Next Case Katie’s Kittens Katie loves cats: she owns 12.

One of Katie’s queens, Kathleen, had her first litter of kittens last week: 5 born live and 1 born dead.

Katie says a kitten (no name yet)

died yesterday and the some of the other kittens are very lethargic and not nursing well.

Kitten’s Clinical Exam

Three kittens have a fever.

Most are weak.

Several have a moist, red, swollen umbilicus.

You start the kittens on antibiotics and submit blood for culture.

Blood Culture Result

BAP at 24 hours

Gram stain

Clear zone of hemolysis around small translucent colony.

What’s Your Diagnosis?

SepticemiaStrep canis

aka Group G Streptococcus

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What is the most probable source of infection?

A. Contaminated litter box

B. Skin of human owner

C. Vagina of the queen

D. Mouth of the tom cat?

Source = vagina of queen 50% or more cats <2 yr old are carriers

Opportunistic pathogenInvasion of neonate via umbilicusRapid dissemination septicemia / bacteremiaPrevention: disinfect umbilicus2% tincture of iodine

Kittens of immune dams get antibodies via colostrumThus, kitten septicemia due to Strep. less frequent in older queens

Diagnosis: cultureAntibiotic resistance not a problemPenicillin or ampicillin 1st drug of choice

Source = vagina of queen 50% or more cats <2 yr old are carriers

Opportunistic pathogenInvasion of neonate via umbilicusRapid dissemination septicemia / bacteremiaPrevention: disinfect umbilicus2% tincture of iodine

Kittens of immune dams get antibodies via colostrumThus, kitten septicemia due to Strep. less frequent in older queens

Diagnosis: cultureAntibiotic resistance not a problemPenicillin or ampicillin 1st drug of choice

Key Elements of the Story

What Strep Has Similar Epidemiology in Humans?

50% case fatality rate in 1970s

10% - 30% of pregnant women are colonized with GBS.

What Does Group G Mean?

Schematic from: http://www.bact.wisc.edu/bact330/lecturespyo

Strains of Strep. can be distinguished based on cell wall carbohydrates, known as Lancefield antigens. Commercial agglutination tests allow for rapid identification of Strep. GROUPS.

Next Case Case: Rita’s Wrist

Adult human

Infected wound

Rapid progression

Extensive tissue destruction

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24 hour BAP culture

Culture results What’s Your Diagnosis?

Necrotizing fasciitis Streptococcus pyogenes

Group A Strep

NNFF = true stories

Source = exogenous or endogenousInoculation: wound, surgery, burn, virus. Host immunologically vulnerableInvasion – inflammation (PMN) – dissemination S. pyogenes exceptionally virulent strain

– named by the press “Flesh Eating Bacteria”resists phagocytosis: M proteinkills phagocytes: leukotoxinPyrogenic exotoxins A, B, C… = Superantigens

Source = exogenous or endogenousInoculation: wound, surgery, burn, virus. Host immunologically vulnerableInvasion – inflammation (PMN) – dissemination S. pyogenes exceptionally virulent strain

– named by the press “Flesh Eating Bacteria”resists phagocytosis: M proteinkills phagocytes: leukotoxinPyrogenic exotoxins A, B, C… = Superantigens

Key Elements of the Story

Superantigens trigger cytokine release Bind MHC-II on antigen presenting cell

(APC) to Vβ region of T cell receptors nonspecifically causing massive activation and cytokine release:

IL-1,IL-6, TNF, IFN tissue destruction & leaky capillaries hypotension hypotension shock death

Story - continuedSuperantigen Binding Site Outside Typical Receptor

Activates only“primed” T-cells

Activation ofALL T-cells

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Flesh Eating BacteriaA well-deserved name

Summary: Strep Virulence Factorsnot all factors are present in all species or strains of Strep.

M-proteins Block phagocytosis Bind fibronectin to covers C’ binding sites Adherence to host cells

Capsule Low immunogenicity

Hyaluronic acid (like host tissue) Polysaccharide

Hydrophilic Impairs phagocytosis

Blocks complement (C’) activation by covering C’ binding sites

Other cell wall proteins Bind Fc portion of antibodies covering

Strep cell with host IgG decreasing C’binding and phagocytosis

Lipoteichoic acid Host cell binding

C5a peptidase Cleaves C5a (chemotaxin) preventing

recruitment of PMNs.

Exoenzymes Streptolysin S

β hemolysin; creates pores in cell membrane Fibrinolysin - fibrin lysis enhances spread of Strep

into deeper tissues

Hyaluronidase DNAases

Superantigens Toxic shock-like toxins

Immunomodulatory; triggers nonspecifc T cell stimulation and cytokine release serious negative affects on multiple organ systems leading to shock and death.

Leukocidin Kills leukocytes

Cell-associated Secreted

Multiple redundant virulence factors make streptococci very common and successful pathogens.

Multiple redundant virulence factors make streptococci very common and successful pathogens.

Immune-Mediated Sequelae Rheumatic fever – after Strep pharyngitis

Heart tissue damage caused by…. Cross reactive antigens: myosin & M-protein Genetic susceptibility of host Immune complex deposition

Acute glomerulonephritis – after skin infections Kidney damage - theories

Immune complex deposition Cross reactive antigens Alteration of glomerular tissues by Strep Complement activation by Strep in glomeruli

Purpura hemmorhagica in horses? Some experts think this is also a immune-mediated disease

triggered by strep infections.

Hemorrhages on mucosa

Edema

Other Strep Infections

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Streptococcus pneumoniaeLobar pneumonia in humans and primates.

The polysaccharide capsule is a critical virulence factor.

77 H1N1 cases evaluated

22 had bacterial pneumonia 10 Strep. pneumoniae

6 Strep. pyogenes

7 Staph. aureus – most MRSA

2 Strep. mitis

Vegetative endocarditisMultiple species of streptococci can cause this condition.

Damaged tissues predisposed to infection.

EnterococcusStrep-like morphology; differentiated by lab tests

Normal flora skin & gut

Opportunistic infections Cystitis, mastitis, endocarditis

Pathogenesis poorly understood

Difficult to treat

Emerging problem Antibiotic resistance acquired in animals can be

transferred to human strains of Enterococcus.

The End