Lecture 6 9/25/23 Flashcards
What are the three gram positive cocci of importance?
-staphylococcus
-streptococcus
-enterococcus
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
What are the characteristics of staphylococcus virulence?
-classified based on coagulase enzyme
-coagulase pos. bacteria are more virulent than coagulase neg. bacteria
Which three coagulase positive bacteria are important for this class?
-Staph. aureus
-Staph. hyicus
-Staph. pseudintermedius
How do staph. bacteria invade the body?
through broken skin or mucous membranes
How do staph. bacteria cause damage?
-inflammation
-destruction of neutrophils
-pus formation
Which staph. species cause purulent infections in dogs and cats?
-S. pseudintermedius
-S. aureus
Which staph. species is the most common isolate from canine pyoderma?
S. pseudintermedius
Why are dogs highly susceptible to purulent staph. infections?
thin skin that can easily be invaded
Which staph. species causes greasy pig disease/exudative epidermititis?
Staph. hyicus
What staph. species causes mastitis in cattle?
S. aureus
What is botryomycosis?
a chronic pyogranulomatous inflammation caused by S. aureus
How does pyogenic inflammation differ from pyogranulomatous inflammation?
-pyogenic inf. involves lots of neutrophils/pus
-pyogranulomatous also involves macrophage pus in addition to neutrophils
What staph. species causes bumble foot/chronic pododermatitis in poultry?
S. aureus
Which toxin-mediated diseases occur in humans as a result of superantigen effects?
-staphylococcal toxic shock syndrome
-staphylococcal food poisoning
-staphylococcal scalded skin syndrome
What types of infections are coagulase-neg. staph. species involved in?
-nosocomial
-UTI
-colonization of catheters and implants
How can staph. species be diagnosed in the lab?
-cytology or gram staining
-routine aerobic culture
-PCR/molecular detection
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
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
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
