Lecture 5: Staphylococcus species

Describe the key features of Staphylococcus

• Facultative Anaerobe

• Gram + Cocci

• Clusters

• Commensal on skin and mucosa

A coagulase assay is a common test performed on bacteria, what is coagulase and what does it do?

• Coagulase is an enzyme that clots plasma into fibrin clots

• Coagulase hides bacteria from PMNs

  • Therefore it positively contributes to a bacteria’s virulence

What are the Coagulase + and Coagulase - staphylococcus?

• C+

  • S. aureus

  • S. pseudintermedius

  • S. coagulans

  • S. hyicus

• C-

  • S. epidermidis

  • S. felis

  • S. chromogenes

Staphylococcus that are CPS (Coagulase psotive staphylococci) and grown on a blood agar plate can create a _____ ___ hemolysis

Double Zone

Staphylococci that are CPS will have _________ and ________

+ Hemolysis and + Coagulase

Why is S. aureus so dangerous?

• It has MANY virulence factors

  • Capsule, Protein A, Extracellular toxins and free coagulase

    • These factors allow it to adhere, invade, survive and cause damage within the host

• It also is antimicrobial resistant

  • MRSA

How did Methicillin Resistant Staphylococcus Aureus (MRSA) get so bad?

• The gene that is responsible for the resistance, SCCmec, can be passed between S. aureus

  • This gene gives S. aureus resistance to all beta-lactams

• Coupled with inappropriate antibiotic use

T/F: SCCmec makes S. aureus more virulent

False, it makes it harder to treat, not necessarily more virulent

What is a Clone?

A group of strains with the same genotype with a common ancestor

S. aureus human and animal clones are different but closely related, why is that an issue?

• Bc it increases the chances for them to be zoonotic

  • MRSA clones easily colonize and spread amongst different host species

Which animal is a major reservoir for MRSA for humans?

Pigs

S. aureus is referred to as a “pathogen for all ________”

Seasons, because it can do it all

What does nosocomial mean?

It means that something is hospital associated

T/F: S. aureus is a primary and opportunistic pathogen

True

T/F: S. aureus is zoonotic and anthropozoonotic

True, it means it can go from animals to humans or from humans to animals

S. aureus is known to cause what affliction in lambs in the UK and Ireland? Describe a bit about the infection

• “Tick pyaemia“ abscesses

  • This is an opportunistic infection by S. aureus

  • The opportunity is triggered by immunosuppression of the host, caused by Anaplasma phagocytophilum (tick borne disease)

  • S. aureus is in the tick bites/wound and then it abscesses into the joints and organs (liver) of the animal

What disease does S. aureus subsp. anaerobius cause? and in what species?

• Morel’s Disease in Sheep/Goats

  • Abscesses near cervical lymph node and in lungs

  • The abscesses are caused by coordination w. Cornybacterium pseudotuberculosis (which causes Caesous lymphadenitisi)

What common foot disease does S. aureus cause in raptors/poultry?

Bumblefoot

S. aureus causes what disease in guinea pigs?

Pododermatitis

S. aureus is a VERY common cause of ______ _____ _____ in cattle

Chronic Bovine Mastitis

S. aureus is a ______ mastitis pathogen in cattle

• Contagious

  • transmits between the environment, humans, and cattle

Why does the S. aureus that causes C.B.M in cattle have a poor response to antimicrobials?

• This iteration of S. aureus “hides“ in abscesses within the udder

  • The antimicrobials don’t work because they can’t reach the bacteria

How is C.B.M managed in herds?

Since antimicrobials are not effective against this form a S. aureus infected cattle must be culled or segregated

What type of S. aureus cause C.B.M in cattle?

S. aureus clone ET3

What is the severe form of C.B.M called?

Severe Chronic Mastitis botryomycosis lesions

T/F: CNS bacteria are normal flora of the of the udder

true

What is the new definition for some CNS bacteria?

Mammaliicoccus species

What is the most important CPS in dogs?

Staphylococcus pseudointermedius

T/F: 90% of dogs are colonized with S. pseudointermedius

True

S. pseudointermedius is both _______ and ________ to dogs

Commensal, pathogenic

S. pseudointermedius has similar virulence factors to which other CPS bacteria?

• S. aureus

  • S. pseudointermedius is coagulase and catalase +

    • It produces exfoliative toxins that damage epidermal cells and cause pyoderma

What happens when dogs with S. pseudointermedius infection are treated with Cephalexin?

• Within 1 week they detected MRSP

  • the Cephalexin selects for MRSP by removing the sensitive strains of S. pseudointermedius

What is co-selection and why is it so dangerous?

• The treatment of one antimicrobial can select for resistance across antimicrobial classes

  • It can create resistance superbugs

1. S. pseudointermedius

   1. Low

   2. Dogs

   3. Very Common

   4. Frequent

2. S. aureus

   1. Increased

   2. Humans, livestock, horses

   3. Less common

   4. Rare

CPS are ________ pathogens in inflamed ears, what 2 species are usually responsible for chronic otitis externa in canines?

• Opportunistic

• S. pseudointermedius and S. coagulans

All Staphylococcus species (CPS and CNS) produce the ______ enzyme, what conditions can this enzyme cause?

• Urease

  • Hydrolyses urea and causes UTIs and or Bladder Stones

Staphylococcus felis is a pathogenic ___ in cats

CNS (Coagulase Negative Staphylococcus)

What are some C.S of S. felis?

• UTIs

• Otitis externa, dermatitis, abscesses, wound infections

T/F: S. felis has low zoonotic potential

True, but it still can be zoonotic

What is the staph species found in pigs? Is it CNS or CPS?

• Staphylococcus Hyicus

  • CPS, but an abnormal one

Why is S. Hyicus an abnormal CPS?

• It is non-hemolytic

• Produces “china-white“ colonies

• Variable to have coagulase 50/50

What common pig disease does S. hyicus cause?

Greasy Pig Disease

What are some clinical symptoms of a S. hyicus infection in pigs?

• Contagious, debilitating dermatitis in young pigs

  • Secondary bacterial infections

S. hyicus produces an ______ toxin

• Exfoliative

  • irulence factors produced by the bacterium Staphylococcus hyicus, which cause exudative epidermitis, commonly known as greasy pig disease

T/F: CPS are pathogenic while CNS are not

False

T/F: S. pseudointermedius is more common than S. aureus in dogs

True

T/F: Clones are unique to each animal species and cannot spread between humans an animals

False

T/F: The staphylococci MecA gene confers resistance to all beta-lactam antimicrobials

False, it provides resistant to most not all beta-lactams

T/F: Antimicrobial treatment for canine dermatitis can select for multidrug-resistant resistant-MRSP

True

T/F: Exudative epidermitis in pigs is caused by strains of S. hyicus, which produce a toxin causing damage to the epithelial cells

True (Exfoliative toxin)