Microbiology Flashcards
What is the pathogenesis of a pathogen?
Adhere/colonise and invade
Evade host defences
Multiply/ complete life cycle
Exit host (host is damaged)
What is virulence?
Capacity of a microbe to cause damage to the host
What is the action of adhesin?
Enables binding of the organism to the host tissue
What is the action of invasin?
Enables the organism to invade a host cell/tissue
What is the action of impedin?
Enables the organism to avoid host defence mechanisms
What is the action of aggressin?
Causes damage to the host directly
What is the action of modulin?
Induces damage to the host indirectly
What are virulence factors?
Molecules produced by bacteria, viruses, fungi, and protozoa that add to their effectiveness
What microbes are found on the skin?
Staphylococci Staphylococcus aureus Diptheroids Streptococci Bacillus Candida Malessezia Mycobacterium
What is coagulase?
The ability of a microbe to coagulase plasma, this helps with colonisation and allows a community of bacteria to grow
Who is mostly affected by MRSA?
Eldery and immunocompromised ICU Burns patients Surgical patients IV lines Dialysis patients
What superficial lesions can S.aureus cause?
Boil to abscesses
What toxinoses can S.aureus cause?
Toxic shock
Scalded skin syndrome
What are some important virulence factors of S.aureus?
Fibrinogen binding protein TSSF-1 (toxin) Adhesin Kills leukocytes Shock, rahs, dequamation PVL
What can PVL S.aureus cause?
Necrotising pneumonia
Recurrent furunclulosis
Sepsis
Necrotising fascitis
What skin infections can staph auerus cause?
Rash Folliculitis Abscess Carbuncle Impetigo Scalded skin syndrome
What are the symptoms of TSST-1?
Rapid progression High fever Vomiting Diarrhoea Sore throat Muscle pain
What are the symptoms of scalded skin syndrome?
Exfolatin toxins in the face, axillla and groin
Often neonatal
What is the superantigen TSST-1 associated with?
Toxic shock syndrome
What are the symptoms of necrotizing pneumonia?
Infleunza like syndrome Necrotising haemorrhagic pneumonia Rapid progression Acute respiratory distress Deterioration in pulmonary function Refractory hypoxeamia Multi-organ failure despite antibiotic therapy
How would you class streptococcus pyogenes?
Streptococci
Gram +ve cocci
Catalase nergative
Beta haemolysis
What skin infections can S.pyogens cause?
Impetigo
Cellulitis
Necrotising fascitis
What is cellulitis?
Deep skin infection that is not associated with necrosis
What ks necrotizing fascitis?
Invasive strep A strains penetrate mucous membrane and develop in lesion
Rapidly destroys connective tissue
What is a superantigen?
Class of antigens that cause non-specific activation of T cells resulting in polyclonal T cell activation and massive cytokine release
What is a baceriophage?
A virus that parasitizes a bacterium by infecting it and reproducing inside it
