14 Skin and bones

Question 1

define colonisation

Answer 1

the presence of bacteria on the skin, a mucous membrane or a wound without any symptoms of signs of infection

Question 2

name 4 permanent residents on skin

Answer 2

staphylococci
corynebacteria
propionibacteria
acinetobacter

Question 3

what are temporary residents in the microbiology of normal skin and give an example

Answer 3

not everyone has then

S. Aureus

Question 4

what are transient flora in the microbiology of normal skin and give 2 examples

Answer 4

can be on skin but usually short lived

coliforms (bowel organisms) and pseudomonas

Question 5

what are the 2 main pathogens of skin and soft tissue

Answer 5

Staph Aureus
Strep Pyogenes (group A)
both gram positive
cluster vs chains

Question 6

infections caused by S. Aureus

Answer 6

pustular lesions- spots, boils, abscesses
impetigo
cellulitis- layers directly below skin
infected wounds
venflon infections (cannula)
toxin-mediated

Question 7

infections caused by S. Pyogenes

Answer 7

impetigo
erysipelas- face
cellulitis
necrotising fasciltis (flesh-eating bug, severe and rapidly progressing, antibiotics don't work, surgery and poss amputation)
scarlet fever (toxin-mediated)

Question 8

antibiotic therapy for Staph Aureus

Answer 8

flucloxacillin
co-amoxiclav
OR
erythromycin
clindamycin
cefuroxime
vancomycin

Question 9

antibiotic therapy for Strep Pyogenes

Answer 9

penicillins
OR
erythromycin
clindamycin
cefuroxime
vancomycin

Question 10

MRSA mechanism of resistance

Answer 10

altered cell wall- penicillin binding protein 2a (low affinity for penicillins), this is main target sit for penicillins in S Aureus
cross-resistant to all beta lactam antibiotics, and usually resistant to macrolides

Question 11

advantage of topical antibiotics

Answer 11

high conc of antibiotic at site of action
can use agents too toxic for systemic use
cheap
combination preparations available (+/- steroids) (most dermatology conditions of skin can use steroids but infection, so if use both then good chance of getting rid of rash)

Question 12

disadvantages of topical antibiotics

Answer 12

may not penetrate site of infection
can get systemic absorption
resistance can emerge

Question 13

define disinfectant

Answer 13

chemical with ability to destroy or inactivate potentially pathogenic micro-organisms
e.g. hypochlorite, glutaraldehyde

Question 14

define antiseptic

Answer 14

disinfectant that can be applied to skin or mucous membranes

e.g. iodine, chlorhexidine, isopropanol

Question 15

define topical antibiotic

Answer 15

natural or synthetic drug with anti-microbial activity

e.g. mupirocin, fusidic acid (fucidin)

Question 16

where can topical antibiotics be used

Answer 16

skin and mucosal membranes (oropharynx, nose, eyes, ears, vagina)

Question 17

drug for candida (thrush)

Answer 17

nystatin

Question 18

drug for conjunctivitis

Answer 18

chloramphenicol drops or tetracycline ointments

Question 19

drug for eradication of S Aureus colonisation in nasal passage

Answer 19

mupirocin

Question 20

drug for impetigo

Answer 20

fucidin cream

Question 21

drug for cold sores

Answer 21

acyclovir

Question 22

drug for fungal infections

Answer 22

azoles e.g. canestan

Question 23

drug for vaginal thrush

Answer 23

azoles

Question 24

what is septic arthritis

Answer 24

bacterial infection of a joint

Question 25

septic arthritis- differential diagnosis

Answer 25

gout acute osteoarthritis inflammatory illness reactive arthritis

Question 26

principle pathogens of septic arthritis

Answer 26

S. Aureus | Strep Pyogenes and other streps

Question 27

clinical features of septic arthritis

Answer 27

pain, inflammation, joint effusion (increased synovial fluid), restricted movement, pyrexia (raised body temperature, fever), systemic sepsis

Question 28

septic arthritis is usually a metastatic infection, define this, how else could the infection occur

Answer 28

when bacteria gets to the area via the bloodstream | or might follow a joint injection e.g. steroid joint injection

Question 29

how is septic arthritis diagnosed

Answer 29

``` joint aspirate (removing fluid)- microscopy, culture, sensitivity blood cultures ```

Question 30

how is septic arthritis treated

Answer 30

high dose IV antibiotics for 2 weeks then 4 weeks of oral antibiotics strep= use benzylpenicillin S Aureus= use flucloxacillin (vancomycin if MRSA)

Question 31

what is osteomyelitis

Answer 31

acute or chronic infection of bone

Question 32

osteomyelitis differential diagnosis

Answer 32

tumour, degenerative OA

Question 33

principle pathogens of osteomyelitis (5)

Answer 33

``` S Aureus Streptococci Mycobacterium Tuberculosis Pseudomonas Salmonella ```

Question 34

clinical features of osteomyelitis

Answer 34

pain, swelling, fever, systemic sepsis, deformity, collapse, fracture

Question 35

diagnosis of osteomyelitis

Answer 35

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

Question 36

treatment of osteomyelitis

Answer 36

high dose IV antibiotics | 6 weeks and maybe surgical drainage

Question 37

describe chronic osteomyelitis

Answer 37

osteomyelitis can develop into chronic osteomyelitis formation of dead bone tissue formed within a diseased or injured bone (sequestrum) difficult to manage often months of antibiotics required and surgery often relapses