14 Skin and bones Flashcards

1
Q

define colonisation

A

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

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2
Q

name 4 permanent residents on skin

A

staphylococci
corynebacteria
propionibacteria
acinetobacter

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3
Q

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

A

not everyone has then

S. Aureus

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4
Q

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

A

can be on skin but usually short lived

coliforms (bowel organisms) and pseudomonas

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5
Q

what are the 2 main pathogens of skin and soft tissue

A

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

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6
Q

infections caused by S. Aureus

A
pustular lesions- spots, boils, abscesses
impetigo
cellulitis- layers directly below skin
infected wounds
venflon infections (cannula)
toxin-mediated
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7
Q

infections caused by S. Pyogenes

A
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)
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8
Q

antibiotic therapy for Staph Aureus

A
flucloxacillin
co-amoxiclav
OR
erythromycin
clindamycin
cefuroxime
vancomycin
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9
Q

antibiotic therapy for Strep Pyogenes

A
penicillins
OR
erythromycin
clindamycin
cefuroxime
vancomycin
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10
Q

MRSA mechanism of resistance

A

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

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11
Q

advantage of topical antibiotics

A

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)

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12
Q

disadvantages of topical antibiotics

A

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

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13
Q

define disinfectant

A

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

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14
Q

define antiseptic

A

disinfectant that can be applied to skin or mucous membranes

e.g. iodine, chlorhexidine, isopropanol

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15
Q

define topical antibiotic

A

natural or synthetic drug with anti-microbial activity

e.g. mupirocin, fusidic acid (fucidin)

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16
Q

where can topical antibiotics be used

A

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

17
Q

drug for candida (thrush)

A

nystatin

18
Q

drug for conjunctivitis

A

chloramphenicol drops or tetracycline ointments

19
Q

drug for eradication of S Aureus colonisation in nasal passage

A

mupirocin

20
Q

drug for impetigo

A

fucidin cream

21
Q

drug for cold sores

A

acyclovir

22
Q

drug for fungal infections

A

azoles e.g. canestan

23
Q

drug for vaginal thrush

A

azoles

24
Q

what is septic arthritis

A

bacterial infection of a joint

25
Q

septic arthritis- differential diagnosis

A

gout
acute osteoarthritis
inflammatory illness
reactive arthritis

26
Q

principle pathogens of septic arthritis

A

S. Aureus

Strep Pyogenes and other streps

27
Q

clinical features of septic arthritis

A

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

28
Q

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

A

when bacteria gets to the area via the bloodstream

or might follow a joint injection e.g. steroid joint injection

29
Q

how is septic arthritis diagnosed

A
joint aspirate (removing fluid)- microscopy, culture, sensitivity
blood cultures
30
Q

how is septic arthritis treated

A

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

31
Q

what is osteomyelitis

A

acute or chronic infection of bone

32
Q

osteomyelitis differential diagnosis

A

tumour, degenerative OA

33
Q

principle pathogens of osteomyelitis (5)

A
S Aureus
Streptococci
Mycobacterium Tuberculosis
Pseudomonas
Salmonella
34
Q

clinical features of osteomyelitis

A

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

35
Q

diagnosis of osteomyelitis

A

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

36
Q

treatment of osteomyelitis

A

high dose IV antibiotics

6 weeks and maybe surgical drainage

37
Q

describe chronic osteomyelitis

A

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