Skin and Bones

Question 1

List the permanent residents of normal skin

Answer 1

staphlococci (s.epidermidis, s.capitis)
corynebacteria (diphtheroids)
propionibacteria (acne)
acinetobacter

Question 2

Name a temporary common resident of normal skin

Answer 2

S.aureus

Question 3

Name a transient resident of normal skin

Answer 3

coliforms, pseudomonas

Question 4

What three bacteria are prone to colonisation with more pathogenic bacteria

Answer 4

S.aureus
streptococci
pseudomonas

Question 5

Name the two main pathogens of skin/soft tissue

Answer 5

staph. aureus

strep. pyogenes

Question 6

Name the common viral and fungal pathogens of skin/soft tissue

Answer 6

viral- herpes viruses - whitlow (HSV), shingles (VZV)

fungal - ringworm, tinea (dermatophytes)

Question 7

What is the antibiotic therapy for staph.aureus

remember some are resistant - MRSA

Answer 7

flucloxacillin

co-amoxiclav

Question 8

What is the antibiotic therapy for strep.pyogenes

Answer 8

penicillins
flucloxacillin

erythomycin
clindamycin

Question 9

What is the mechanism of resistance in MRSA

Answer 9

altered cell-wall - penicillin binding protein 2a (low-affinity now)
PBP2 main target site for penicillins in S.aureus

now cross-resistant to all beta-lactam antibiotics and usually resistant to macrolides (erythomycin)

Question 10

What are the advantages and disadvantages to topical antibiotics

Answer 10

Ads- high conc at site of infection, can use ones too toxic for systemic use, cheap and there are combinations

dis- may not penetrate to site of infection, can get systemic absorption, resistance

Question 11

Define disinfectant

Answer 11

chemical with the ability to destroy or inactivate potentially pathogenic micro-organisms

Question 12

Define antispetic

Answer 12

disinfectant that can be applied to skin or mucous membranes

Question 13

Define topical antibiotic

Answer 13

natural or synthetic drug with anti-microbial activity

like a lotion - for skin or mucosal membranes

Question 14

Name some common uses for topical antibiotics

mouth
eyes
nose
skin
vagina

Answer 14

mouth - nystatin - thrush
eyes - chloramphenicol drops/tetracycline ointments - conjunctivitis
nose - mupirocin cream - s.aureus eradication
skin - fucidin cream - impetigo
azoles- fungal
vagina - azoles - thrush

Question 15

What are the principle pathogens for septic arthritis

Answer 15

s. aureus

strep. pyogenes, pneumococcus

Question 16

what are the clinical features of septic arthritis

Answer 16

pain, inflammation, joint effusion, restricted movement, pyrexia, systemic sepsis

Question 17

How do you diagnose septic arthritis

Answer 17

joint aspirate - microscopy, sensitivity

blood culture

Question 18

How do you treat septic arthritis

Answer 18

high dose IV antibiotics
4 weeks oral after

streptococci- benzylpenicillin
s.aureus - flucloxacillin (vancomycin if MRSA)
formal washout

Question 19

What is osteomyelitis

Answer 19

acute or chronic infection of bone
usually metastatic spread of infection

differential diagnosis - tumour, degenerative OA

Question 20

What are the principle pathogens with osteomyelitis

Answer 20

staph.aureus
streptococci
mycobacterium tuberculosis

Question 21

What are the clinical features of osteomyelitis

Answer 21

pain, swelling 
fever
systemic sepsis
deformity 
collapse (vertebra), fracture

Question 22

How do you diagnose osteomyelitis

Answer 22

x-ray, bone scan, MRI scan
blood cultures
bone biopsy

Question 23

How do you treat acute osteomyelitis

How is this different to chronic osteomyelitis

Answer 23

acute - high dose IV antibac 6 weeks
surgical drainage

chronic - formation or sequestrum, months of antibiotics and surgery
relapse possible