Staphylococcus 1 Flashcards by Nicole Kuehne

What are the major points to understand about Pathogenic Streptococcus spp?

tend to be species-adapted

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With staphylococcus what test is used to determine if its Staphylococcus aureus or other type of Staph?

coagulase test - S. aureus is coagulase pos

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Transmission of Staphylococcus spp. can occur how?

via exogenous or endogenous spread

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What factors would predispose and animal to Staphylococcus?

Compromise in the integrity of skin or mucous membrane
Impairment in some other host defense
Presence of a foreign body - e.g. catheter, suture, prosthesis

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What are the cell associated virulence factors of Staphylococcus?

capsule, protein A, adhesions

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What is the purpose of protein A virulence factor?

avoid phagocytosis

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Exotoxins are a virulence factor for Staphylococcus. What is their pathogenic effect?

Food poisoning in humans

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What are the three Staphylococcus species of veterinary importance?

S. auerus, S. pseudointermedius, S. hyicus

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Of the three veterinary importance Staphylococcus which ones are coagulase positive?

S. aureus
S. pseudintermedius

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Clinical conditions due to S. aureus in sheep are:

Tick pyemia, mastitis, dermatitis

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S. aureus causes what in horses?

Scirrhous cord - botryomycosis of the spermatic cord

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S. pseudintermedius in dogs causes what?

Pyoderma, endometritis, cystitis, otitis externa and other suppurative conditions

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If we are culturing Staphylococcus what would we see on blood agar?

Observe for colony morphology

Hemolysis

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What biochemical tests are used for diagnosing staphylococcus spp?

Catalase
Coagulase
DNase
Latex agglutination tests

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T or F Staphylococcus spp. are non-fastidious.

True - grow on non-enriched media

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What do staphylococcus colonies look like on medium?

yellowish/golden (especially S. aureus)

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What type of test would you utilize to distinguish between S. aureus and S. epidermidis?

Tube coagulase test

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Methicillin-resistance (MR) is the major cause of antibiotic resistance with Staphylococcus. What encodes for this resistance? Which antibiotic is it resistant against?

mec A/C gene, resistance to beta-lactam antibiotics

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Due to multidrug resistance staphylococcal infections in animals, what antibiotics are veterinarians left with for treatment?

rifampicin, chloramphenicol, aminoglycosides, newer antimicrobial agents

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What are the three major points to understand about Staphylococcus spp?

major opportunistic pathogen, associated pyogenic infections, mainly involved in skin and soft tissue infections

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T or F Some Enterococci are of emerging importance because of innate resistance to most common antimicrobials

TRUE

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What test do we use to determine if its staphylococcus or streptococcus?

staph is catalase positive, step and enterococcus are catalase negative

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Staphylococcus are Gram () that form clusters

Gram (+)
irregular clusters that resemble a bunch of grapes

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Staphylococcus spp. are resistant to what enzyme?

lysozyme

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What type of infection to Staphylococcus spp. cause?

pyogenic infections (via opportunistic pathogens)

T or F Staphylococcus spp. are only a cause of secondary infection.

False can be primary or secondary infection

Staphylococcus spp. virulence factor capsule has what pathogenic effect?

Anti-phagocytic

Adhesins allow Staphylococcus to not only bind to host cells but is important for formation of what?

Biofilms

What staphlococci exotoxin is a superantigen in humans?

Toxic Shock Syndrome Toxin

What causes desquamation as an exotoxin?

Exfoliative toxin

What is the pathogenic effect of hemolysins and leukocidin?

hemolysin: Destroy red blood cells leukocidin: Kills polymorphonuclear leukocytes

What exoenzymes pathogenic effect is the break down of hydrogen peroxide?

catalase

Which exoenzymes pathogenic effect is to promotes clotting; may lead to walling off the infection site?

coagulase

How many species are there of Staphylococcus?

over 50

Staphylococcus pseudintermedius is isolated from what species?

dogs and cats

S. aureus can be hosted in what species?

cattle, sheep, horses, and poultry

Clinical conditions due to S. aureus in cattle are:

Mastitis

S. aureus causes what in poultry?

bumblefoot

S. hyicus in pigs causes what?

Exudative epidermitis (greasy-pig disease)

S. equorum is a commensal in what species?

horse

S. felis is a commensal in what species?

cats

S. equorum and S. felis are coagulase ___?

negative

What specimens can be used for diagnosis of Staphylococcus?

Pus, milk or other suitable specimens

When culturing Staphylococcus, what medium do we use?

Blood agar and selctive medium

If we are culturing a sample and suspect Staphylococcus, which selective media would be used?

MSA and Purple Agar

PCR is used to detect what with Staphylococcus spp?

To detect MRSA, MLST

What type of oxygen content do Staphylococcus require?

Facultative anaerobes

T or F Staphylococcus species are mostly salt tolerant, catalase (+), non-motile, and non-spore forming

TRUE

How quickly do Staphylococcus grow on medium?

Rapid growth in 18-24 hours at 37°C

hemolysis on blood agar can be variable with Staphylococcus. What does this mean?

Depends on species can be non-hemolytic, single hemolysis, or double hemolysis

S. aureus and S. pseudintermedius produce what type of hemolysis on blood agar

Produce double haemolysis on sheep blood agar

The use of Mannitol Salt Agar (MSA) is used to differentiate between what spp?

Differentiates staphylococci from coliforms and streptococci

What staph spp. causes yellow fermentation on purple agar?

S. aureus - this is due to fermenting the maltose

Since Staphylococcus spp are normal commensals, where are they found on the body?

skin, mucous membranes, URT, lower urogenital tract, trasient flora of GIT

Which type of staphylococci (coagulase positive or negative) can cause infections?

both

Staphylococcus spp. can be cultured on what agar?

blood agar

What are the common clinical conditions seen in dogs and cats due to Staphylococcus spp?

pyoderma, otitis externa, mastitis, osteomyelitis, wound infection

Why are Methicillin-resistant staphylococcal infections important to understand in vet med?

Difficult to treat, may display multidrug resistance

T or F Staphylococci are catalase-negative

False - they are positive

T or F Only coagulase-positive staphylococci are pathogenic

False: both can cause infections

T or F Staphylococcus hyicus is non-hemolytic

TRUE

T or F Staphylococcus aureus and Staphylococcus pseudintermedius are non-hemolytic

False: they are both hemolytic

T or F Staphylococcus aureus is responsible for greasy pig disease/exudative epidermitis

False: S. hyicus via exfoliative toxin

What virulence factors of Staph are the exoenzymes?

Catalase -Lipase -Elastase -Hyaluronaidase