Bacterial Virulence and Skin Infections Flashcards
Define virulence factors
Individual factors that can be tied down to a particular protein that makes it more effective at causing disease
Describe virulence factor adhesin
enables binding of the organism to host tissue
Describe virulence factor impedin
enables the organism to avoid host defence mechanisms
Describe virulence factor aggressin
causes damage to the host directly
Staphylcoccus aureus is a gram ___1__ organism. It is also coagulase ___2______it grows best in ____3___
1) positive
2) positive
3) aerobic conditions but can grow anaerobically (facultatively anaerobic)
Staphylcoccus epidermis is a gram ___1___ organism but coagulase ___2____
1) positive
2) negative
Staph Epidermis is largely ___1____, usually doesn’t cause ____2______ unless in ____3_____
1) self-limiting
2) serious infections
3) hospitals
MRSA is defined by resistance to what?
Flucloxacillin
Describe TSST-1 and super antigens.
TSST-1 is a super antigen that causes toxic shock. Super antigens cause massive release of cytokines & inappropriate immune response. Cytokine storm. Over stimulation of T cells due to non-specific activation of T cells.
Strep pyogenes is a gram __1___ organism that causes ___2____ haemolysis. It is a group _3___ streptococci which can be further divided according to __4_____
1) positive
2) beta
3) A
4) M protein antigens
What organism that can also cause skin problems cause strep sore throat, pharyngitis and scarlet fever?
Strep pyogenes
What two bacteria are usually involved in skin infections?
Staph Aureus and Strep Pyogenes
Describe Impetigo
Highly contagious, relatively superficial as the infection is immediately below the surface, tend to see it in young children.
Describe cellulitis
Deeper skin infection in the dermis that is not associated with necrosis, patient more likely to have fever, feel sick, vomiting, more of an immune response
Describe necrotising fasciitis
Strain penetrates mucous membrane and develop in lesion, rapidly destroys connective. Seems to be linked with streptolysin S (pore forming cytolysis, toxic to PMN, organelles, platelets, important in animal models.
Antibiotic of choice for staph A infection
flucloxacillin
Antibiotic of choice in MRSA?
no flucloxacillin. Use doxycycline, co-trimoxazole, clindamycin and vancomycin.
What does PVL toxin produced by staph a cause?
Necrotising pneumonia
Antibiotic of choice with strep pyogenes?
Sensitive to penicillin but if you are not sure if the infection is staph or strep then you should use flucloxacillin instead as that will cover both organisms.
Name 3 skin commensals unlikely to be the cause of a problem?
Staph epidermis, corynebacterium (diphtheroids) and propionibacterium
Dermatophytes are __1____ that infect ___2__ examples are __3___ which cause a ___4______
1) fungi
2) keratinised tissues (skin, hair, nails)
3) tinea- ring worm
4) ring appearance rash
Describe candida infections
fungal infection that occurs in the skin folds.
Example of an anti fungal?
clotrimazole (if it ends in azole it is an anti-fungal)
Describe scabies and treatment?
Causes an itchy rash, give malathion or benzyl benzoate lotion
