Gram Positive Pathogens - Robison Flashcards
Staphylococcus- General Facts
In every human’s microbiota
Can be oportunistic pathogens
What is the structure and physiology of Staphylococcus?
Gram positive cocci are non-motile, faculative aerobes, with irregular clusters
Catalase Positive
Describe S. epidermidis
most common organism on the surface of skin
coagulase negative, mannitol negative, and mostly opportunistic infections
Describe S.aureus
carried by 30-50% of healthy population
coagulase positive, mannitol positive, and more virulent
What are the three categories of Staphylococcal disease?
Non invasive - indegestion
Cutaneous - various skin conditions
Systemic
What are the Staphylococcal defenses against phagocytosis?
Inhibits the complement system by covering surface with protein A
Converts fibrinogen to fibrin with coagulase to not form blood clots; keeps its self surrounded by fibrin capsule
Which bacteria produces more toxins? S. aureus or S. epidermis?
S. aureus
What are cytolytic toxins?
pore forming toxins
What are exfoliative toxins?
causes skin cells to seperate from eachother
What are toxic- shock syndrome toxins?
causes toxic shock syndrome due to superantigen
What are some skin related diseases caused by staphylococus?
impetigo, boils (furuncle), carbuncle, scalded skin syndrome
What are some systemic diseases caused by staphylococcus?
TSS, bacteremia, endocarditis, pneumonia, osteomyelitis
Treatments for staphylococcus diseases
Methicillins for most infections
Vancomycin for MRSA
How are staphylococcus infections and diseases mostly passed?
endogenous source and easily transmitted by contact
What is the morphology and physiology of streptococcus?
Gram positive coccus arranged in pairs or chains
Aerotolerant anaerobes
What is in the Group A Streptococcus and what are characteristics?
S. pyogenes
pathogenic strains often form a capsule
can cause disease if the normal microbiota is depleted, large amounts develop, or specific immunity impaired