Lesson 1 to Lesson 2 Flashcards
relative capacity of a pathogen to damage a host
virulence
A dairy farmer notices a decline in milk production in several cows. Upon examination, the cows have swollen udders with thickened secretions. Laboratory results reveal a Gram-positive, catalase-positive, coagulase-positive coccus. Which organism is the most likely cause?
A) Streptococcus uberis
B) Staphylococcus aureus
C) Streptococcus agalactiae
D) Staphylococcus hyicus
Staphylococcus aureus
- A veterinarian examines a young pig suffering from widespread greasy exudates and exfoliation of the skin. Laboratory culture reveals Gram-positive cocci. What is the most likely causative agent?
Staphylococcus hyicus
A horse presents with a chronic, suppurative granulomatous infection at the site of a recent castration. The lesion is firm and nodular. Gram staining reveals Gram-positive cocci in clusters. What is the likely diagnosis?
Botryomycosis caused by Staphylococcus aureus
commensals living in skin or mucous membranes take advantage of impaired antimicrobial defenses of the hosts and behave as opportunistic pathogens
endogenous infections
A veterinarian treats a dog with recurrent otitis externa. A culture from the ear canal reveals Gram-positive cocci that are catalase-positive and coagulase-positive. The infection is resistant to beta-lactam antibiotics. What is the most likely organism?
Methicillin-resistant Staphylococcus aureus (MRSA)
A lamb develops septicemia and multiple abscesses following tick infestation. Ixodes ricinus is identified as a vector involved in disease transmission. What is the most likely causative agent?
Staphylococcus aureus
What is the major virulence factor contributing to the tissue necrosis seen in bovine staphylococcal mastitis?
Alpha toxin
- A pig farm experiences an outbreak of exudative epidermitis in piglets. What is the primary mode of entry of Staphylococcus hyicus into the host?
A) Inhalation of contaminated air
B) Ingestion of contaminated feed
C) Skin abrasions
D) Direct penetration through intact skin
Skin abrasions
A horse presents with high fever, nasal discharge, and abscessed lymph nodes around the throat. The veterinarian suspects strangles. What is the most likely causative agent?
Streptococcus equi subsp. equi
A dairy herd experiences an outbreak of mastitis. Laboratory tests confirm Streptococcus agalactiae as the causative agent. What is the most effective method to control transmission?
A) Quarantine affected cows
B) Vaccinate the herd
C) Improve milking hygiene and sanitation
D) Increase dietary protein
Improve milking hygiene and sanitation
What type of hemolysis is most commonly associated with highly pathogenic Streptococcus species?
Beta-hemolysis
A veterinarian submits a sample of pus from a swollen lymph node*in a horse with suspected strangles. What is the best laboratory test to confirm Streptococcus equi?
A) Coagulase test
B) Sugar fermentation test
C) Lancefield grouping
D) Urease test
C) Lancefield grouping
Which of the following species is commonly associated with summer mastitis in cattle?
A) Streptococcus pyogenes
B) Streptococcus dysgalactiae
C) Streptococcus pneumoniae
D) Staphylococcus pseudintermedius
Streptococcus dysgalactiae
main portals of entry of pathogens
mucosae of GI, respiratory, and urogenital tracts
often resistant to phagocytosis
encapsulated bacteria