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
binding of complement and antibody to the bacterial surface
opsonization
produced and secreted by viable bacteria
exotoxins
integral constituents of the bacterial cell wall not released until the microorganms are lysed
endotoxins
detects conserved molecular patterns unique to microorganisms not expressed by the hosts
Pattern Recognition Receptors
Mammals possess a family of transmembrane PRR called as?
Toll-like receptors
microbial patterns which recognize LPS, lipoteichoic acid, DNA from bacteria, glucans from fungi
Pathogen-associated molecular patterns
it detect molecular signatures of microbial pathogens and orchestrate the innate immune response to help initiate adaptive immune response
TLRs
host wherein pathogens are sequestered in a specific organ such as gall bladder or lymph nodes and not exreted in the feces
latent carrier
pathogen is shed in the feces
active carrier
bacteria present in bloodstream without replication
bacteremia
pathogens present in bloodstream that multiply and produce systemic diseases
septicemia
occur when the host fails to eliminate the pathogen
chronic infection
causes suppurative lesion
pyogenic
Staphylococcal diseases of importance in domestic animals
- mastitis
- tick pyaemia
- exudative epidermitis
- botryomycosis
- pyoderma
virulence factor of S. aereus that result to tissue necrosis
alpha toxin
a vector for the rickettsial agent of tick-borne fever
Ixodes ricinus
occurs worldwide in sucklers and weaned pigs up to 3 months of age
greasy pig disease
chronic, suppurative granulomatous condition, occurs within a few weeks of castration in the horse due to infection of the stump of the spermatic cord
botryomycosis
common cause of nosocomial infection in vet hospitals
methicillin-resistant staphylococcal infection in animals
produce double hemolysis
S. aereus and S. pseudointermedius
color of colonies of bovine and human strains of S. aereus
golden yellow
has a role in shielding the organism from phagocytic cells
coagulase
carry S. aureus on their skin and nasal mucosa and infection occurs through minor skin trauma including tick bites
Lambs
What are the principal pathogens involved in streptococcal mastitis?
Streptococcus agalactiae, S. dysgalactiae and S. uberis
Disease outbreaks are most common in intensively reared pigs when they are subjected to overcrowding, poor ventilation and other stress factors.
Streptococcus infections
a febrile disease involving the upper respiratory tract with abscessation of regional lymph nodes of horses
Strangles
