Lecture 6 9/25/23 Flashcards by Danika Boltz

What are the three gram positive cocci of importance?

-staphylococcus
-streptococcus
-enterococcus

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What are the general characteristics of staphylococcus bacteria?

-often commensals of skin and mucous membranes
-can cause primary and opportunistic infections
-can be contagious
-seen in nosocomial infections

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What are the characteristics of staphylococcus virulence?

-classified based on coagulase enzyme
-coagulase pos. bacteria are more virulent than coagulase neg. bacteria

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Which three coagulase positive bacteria are important for this class?

-Staph. aureus
-Staph. hyicus
-Staph. pseudintermedius

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How do staph. bacteria invade the body?

through broken skin or mucous membranes

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How do staph. bacteria cause damage?

-inflammation
-destruction of neutrophils
-pus formation

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Which staph. species cause purulent infections in dogs and cats?

-S. pseudintermedius
-S. aureus

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Which staph. species is the most common isolate from canine pyoderma?

S. pseudintermedius

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Why are dogs highly susceptible to purulent staph. infections?

thin skin that can easily be invaded

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Which staph. species causes greasy pig disease/exudative epidermititis?

Staph. hyicus

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What staph. species causes mastitis in cattle?

S. aureus

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What is botryomycosis?

a chronic pyogranulomatous inflammation caused by S. aureus

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How does pyogenic inflammation differ from pyogranulomatous inflammation?

-pyogenic inf. involves lots of neutrophils/pus
-pyogranulomatous also involves macrophage pus in addition to neutrophils

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What staph. species causes bumble foot/chronic pododermatitis in poultry?

S. aureus

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Which toxin-mediated diseases occur in humans as a result of superantigen effects?

-staphylococcal toxic shock syndrome
-staphylococcal food poisoning
-staphylococcal scalded skin syndrome

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What types of infections are coagulase-neg. staph. species involved in?

-nosocomial
-UTI
-colonization of catheters and implants

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How can staph. species be diagnosed in the lab?

-cytology or gram staining
-routine aerobic culture
-PCR/molecular detection

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What is the limitation associated with using PCR to detect staph.?

staph. is a common commensal and may result in a false positive even if it is not causing the disease

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Why is it important to identify the underlying disease states with staph. infections?

staph. are primarily opportunistic, so just treating the bacterial infection will not fully resolve the problem

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What treatment options are available for staph. infections?

-cleansing shampoo
-topical antibiotic application
-other antimicrobials

What are the characteristics of MRSA and MRSP?

-staph. strains resistant to all beta-lactams
-often multi-drug resistant
-resistance mediated by mecA and mecC genes

Why is infection control important with staph. species?

-can be zoonotic/reverse zoonotic
-household spread and occupational risk possible

What preventative measures can be taken for staph.?

-proper precautions/hygiene
-identifying increased risk
-isolation of infected animals
-education of owners

Why are patients colonized with staph. species not treated?

staph. is mostly a commensal

What are the characteristics of streptococcus bacteria?

-gram pos. cocci in chains -commensals of mucous membranes

What disease is caused by Strep. equi equi?

strangles

What is strangles?

contagious upper resp. disease in horses

What are the characteristics of strangles?

-high morbidity -low mortality -young horses often protected by maternal antibodies

What are the clinical signs of strangles?

-fever -depression -anorexia -dysphagia -moist cough -purulent nasal discharge -lymph node abcess

What are the potential infection complications with S. equi?

-guttural pouch empyema -metastatic/disseminated strangles -purpura hemorrhagica

What is purpura hemorrhagica?

hemorrhage and edema triggered by a hypersensitivity immune reaction

How can S. equi be diagnosed?

-staining/micro. examination -culture -serology -PCR

What are the characteristics of S. equi treatment?

-most animals recover spontaneously following abscess maturation/rupture -can provide treatments for pain relief/speeding recovery -antibiotics only effective if given soon after exposure/sometimes in disseminated cases

What are the characteristics of S. equi control?

-reportable disease in many states -vaccination available

What are the characteristics of S. equi carriers?

-can be asymptomatic, clinical, convalescent, and/or long-term -harbor bacteria in guttural pouch after infection

What are the characteristics of S. equi zooepidemicus?

-opportunistic -broad host range -purulent infections

What are the characteristics of Strep. canis?

-commensal of skin and mucous membranes -causes infections in dogs and cats -can lead to severe bacteremia/septicemia

What are the characteristics of Strep. suis?

-pathogenic or commensal associated with pigs -can lead to severe disease -serious zoonosis

What condition is caused by Strep. porcinus?

jowl abscess in pigs

Which species are able to cause bovine streptococcal mastitis?

-S. agalactiae -S. dysgalactiae -S. uberis

Which strep. species causes subclinical mastitis?

S. uberis

What are the characteristics of Strep. iniae?

-causes acute fulminating septicemia in fish -recognized zoonosis from fish

What are the characteristics of Strep. pyogenes?

-has superantigens -can cause necrotizing fasciitis

What are the characteristics of Strep. pneumonia?

-causes pneumoccocal pneumonia, septicemia, and meningitis -domestic pets can be carriers

How can strep. species be treated/prevented?

-highly susceptible to penicillin -proper wound management and hygeine

What are the characteristics of Enterococcus sp.?

-opportunistic pathogen -normal intestinal flora -natural resistance to beta-lactams, aminoglycosides, clindamycin, and trimethoprim sulfa -developing vancomycin resistance

What is the main virulence factor of Strep. equi?

M protein

When is vancomycin used?

as a last resort, primarily for S. aureus