Organisms Flashcards
Virulence
the capacity of a microbe to cause damage to its host
Pathogen
a harmful organism that produces a pathology
Commensal
an organism that is part of the normal flora
Coagulase test
use to differentiate between Staph. aureus and coagulase negative Staph. (including Staph epidermis)
Haemolysis test
used to differentiate between Streptococci
Group A strep
Strep pyogenes
Group B strep
Strep agalctiaea
Group C/G strep
strep dysgalactiae
Group D strep
strep bovis
Gram Positive Cocci in chains
Staphylococcus aureus
Staphylococcus Epidermidis
Disease presentation of staph aureus
Cellulitis, endocarditis, osteomyelitis, iatrogenic
Disease presentation of staph epidermidis
endocarditis in prosthetic heart valves
Virulence factors
Virulence factors result in disease caused by specific component of pathogen e.g. toxic shock
TSST-1
superantigen which is the commonest cause of toxic shock
Toxic Shock Syndrome diagnostic criteria
Fever (39℃)
Diffuse macular erythroderma and desquamation
Hypotension (≲90 mHg)
≳3 organ systems involved
Panton-Valentine Leukocidin
Specific secreted proteins that form one functional complex that attacks white blood cells (specific toxicity for leukocytes)
Associated with severe skin infections e.g. recurrent furunulosis, sepsis/necrotising fasciitis
Protein A
binds to Fc portion of antibodies, rendering them inaccessible to the opsonins, impairing phagocytosis
Coagulase
protein enzyme tightly bound to the surface of S. aureus which can coat its surface with fibrin upon contact with blood → protects against phagocytosis
Gram Positive Diplococci
Strep pneumoniae
Enterococcus faecium
Enterococcus Faecalis
Disease presentation of strep pneumoniae
Pneumonia
Meningitis
Otitis media
Disease presentation of enterococci
UTIs, and intra-abdominal infections
Gram Positive Cocci in Chains
Strep pyogenes (Group A strep)
Strep agalactiae (Group B strep)
Disease presentation of Group A strep
Tonsilitis
Scarlet fever
Rheumatic fever
cellulitis
Disease presentation of Group B strep?
neonatal sepsis
Gram Positive Bacilli?
Clostridium perfringens
Clostridium difficile
Clostridium tetani
Listeria monocytogenes
Disease presentation of clostridium perfringens?
Gas gangrene
Cholecystitis
Gastroenteritis
Disease presentation of listeria monocytogenes?
meningitis, gastroenteritis, neonatal sepsis
Gram negative diplococci?
Neisseria meningitidis
Moraxella catarrhalis
Gram negative coccobacilli
Haemophilus influenzae
Bordetella pertussis
Acinetobacter
Gram negative bacilli?
E, coli,
proteus,
klebsiella
Vibrios
vibrio cholerae
Spirochetes
treponema pallidum (syphilis)
borrelia burgdorferi (lyme disease)
Bacteria that don’t gram stain
Mycobacterium tuberculosis
Mycoplasma
