Bacterial and viral infections Flashcards
1
Q
-nb commensal bacterial are the normal, non-harmful flora colonizing humans
staphylococcus aureus. not part of resident flora other than in a minority who carry it in nostrils, perineum, armpits
-skin conditions caused by staph aureus (5)
A
- impetigo can also be caused by strep
- cellulitis
- ecthyma
- furunculosis/boils
- scalded skin syndrome
- toxic shoke syndrome
2
Q
-ecthyma - type of lesion (1) forms where(1) complication
A
ecythyma
- an ulcer. forming under a crusted surface infection - eg insect bite, neglected minor trauma.
- heals with scarring - because the ulcer is full thickness of the epidermis. whereas impetigo is only the stratum corneum.
3
Q
furunculosis/boils
- infection of where. who is at increased risk (5). type of lesion (1) morphology (3) course (3). complications (4) rarer complications (2)
- sudden appearance of many furuncles may suggest what (1)
- investigations (4)
- treament. general (1) acute episode (1). anitbiotics when(3) . chronic (1)
A
- infection of a hair follicle
- teenage boys partularly susceptible, diabetes, systemic steroids, skin disease, minor trauma. some individuals may have chronic furunculosis. may carry staph in nose , groin
- nodule - red, with central supperating core. tender
- -*enlarges, may discharge, usually then clears.
- complications - fever, enlarged drainage nodes, scarring. rare ones - septicaemia, caverous sinus thrombosis
- sudden appearance of many may suggest virulent staph inc strains of MRS.
investigating
-Hx and skin examination - check for underlying skin diseases - eg scabies, eczema
-FBC. urine glucose - check for diabetes
-culture swabs - check organism is staph. ab sensitivity
treatment
-general - antiseptic soaps
-acute episode - incision and drainage, ab in eruptions, systemic sx or immunosupressed
-chronic - treat carrier sites nose or groin w topical antibiotics
4
Q
carbuncle
- infection of what (1) dcm (3). Sx (2)
- who is predisposed (1)
- Mx(2)
A
- deep inection of many hair follicles
- dcm - swelling, supperation, discharge from many points
- Sx - pain, systemic upset
- diabetic pts predisposed.
- Mx - topical and systemic. ab incision and drainage may speed up healing but is difficult
5
Q
scalded skin syndrome
- dmc (4)
- who is at risk (2) what is the cause (1)
- Mx(1)
A
- skin - resembles a scalp, tender, erythema, sloughing (=sheding) of patches of stratum corneum
- children, pts with renal failure are at risk. adults usually have antibody to the toxin. cause of a toxic produced by staph from infection elsewhere eg imetigo
- systemic antibiotics
- nb differential in adults is toxic epidermal necrolysis. this involves full thickness damage to epidermis - skin biopsy will distinguish*
6
Q
toxic shock syndrome
- dmc (3). Sx(1). complication (1) course (1)
- cause (1)
- Mx(2)
A
- wide spread eythematous rash. fever.
- complication is shock - i think septic?
- 1-2 wks later initial reaction is followed by desquamation most markedly fingers and hands
- case is staph toxic mainly due to overgrowth of staph in vagina of woman using tampon
- Mx systemic ab and irrigation of infected site
7
Q
streptococcus pyogenes. what infections can be caused by streptococcal bacteria(6)
A
- impetigo
- cellulitis
- erysipelas
- necrotizing fasciitis
8
Q
- erysipelas
- Sx(2). type of lesion(1) dmc(4)
- complications(3)
- Mx
- cause
- course
A
- first Sx malaise, fever
- after a few hours a plaque erupts - erythematous, spreading, well define edge, may blister
- complications - can be fatal if untreated. episodes can affect same area repeatedly. this can cause lymphoedema
- caused by strep entering through broken skin - between toes, behind ears
- Mx - systemic penicillin, sometimes given iv.
- also treat cause of original skin split eg tinea pedis*
9
Q
necrotizing fasciitis - this is rare and is caused by strep plus anaerobes
- at risk pts (2)
- at first resembles what(1) progresses to what (2)
- complication (1)
- Ix (3)
- Mx(2)
- prog(1)
A
- diabetics, post surgery
- at first resembles cellulitis. progresses to necrosis of skin and subcutaneous tissue
- complication - central anaesthetic area due to cutaneous nn damage
- Ix - incision biopsy. culture. MRI to assess spreading.
- Mx - surgical debridement, iv ab
- prognosis is poor
10
Q
impetigo
-caused by staph aureus or streptococcal bacteria or both together
>general rule what type is staph and what type is strep
- type of lesion (1) may become (1)
- d(2)
- course (3)
- Ix (2) and Mx (1)
A
- general rule the bullous type of staph and the ulcerated crusted type is strep
- blisters. may become pustule.
- lesions often multiple and around face. can also affect folicles.
- pustules may rupture leaving exudation and crusting. condition can spread through a family. tends to be self limiting.
- streptococcal impetigo can trigger acute glomerulonephritis.
- examination. swabs for culture. severe cases may need ab.
11
Q
cellulitis - can be caused by staph or strep or other bacteria
- inflammation deeper than erysipelas. often involving subcutaneous tissue
- dcm (2)
- cause
- mx
A
- affected area very swollen. border less well defined than in erysipelas
- cause - usually trauma
- -*Mx - systemic ab, sometimes iv. also rest and elevation.
12
Q
-HPV - viral warts
-some possible patterns (6)
A
- common warts
- plantar warts
- mosaic warts
- plane warts
- facial warts
- anogenital warts
13
Q
HPV - viral warts
-who is most at risk (2). course (1). Mx (1)
A
- school children, immosupressed
- spontaneous resolution as healthy immune response overcomes infection. ranges from months - years in different pts.
- -*Mx either leave warts or cyrotherapy
14
Q
- common warts - type of lesion (1). colour (1). surface (1) d(3) pain?(1)
- planar warts -d(1) pain?(1)
- mosaic warts - d(4)
A
- common warts - papule (or nodule depending on size). skin coloured. irregular surface. hands, face, genitals. usually pain free
- plantar warts - less elevated than common warts. occur on soles of feet. can be painful.
-mosaic warts - multiple small tightly packed individual warts. occur on soles, palms, around finger nails
15
Q
- plane warts. type of lesion (1) surface (1) d(3) colour (1) course (2) c (1) pain?(1)
- facial warts - d(1) pain?(1)
- anogenital warts - type of lesion (2) surface (1) d(1) pain?(1) risk factors (2)
A
- plane warts. papules, smooth, skin coloured. face, shaven legs, backs of hands. become inflammed and resolve spontaneously. not painful. may be arranged in a line.
- facial warts. most common in beard area of men. spread by shaving. not painful
- anogenital warts - papillomatous plaques. moist surface. anywhere in genital region. may be painful. risks - sexual abuse in children, or spreading from common warts elsewhere.
