Bacterial and Viral infections Flashcards
what are commensal bacteria
organism that lives on/with another organism without causing disease/pathology
what are some human bacterial commensals
S.epidermidis (other staph. Bacteria can be but are less common)
Micrococci
Corynebacteria
Proprionibacteria
S.aureus (but only up the nose, otherwise it is usually a pathogen)
when may commensals be infective
if the skin barrier is broken
overproliferation
whats are the pathologies for staph infection
primary infection on normal skin
secondary infection on damaged skin
disease through staphylococci toxin production
what topical and systemic antibiotics are useful for staph infections
topical - fusidic acid, mupirocin
Systemic - flucloxacillin, clindamycin
what are first-line antibiotics for streptococcal infections
- Pen V - only if definitely streptococcal as it doesnt work for staph
- flucloxacillin - 1st line if diagnostic doubt
- clindamycin
what hypersensitivity reactions may occur after streptococcal infection
guttate psoriasis erythema nodosum erythema multiforme vasculitis glomerulonephritis
what is impetigo
staph/strep infection on compromised skin (commonly eczema) - often has a golden crust , highly infective
what is bullous impetigo and who gets it more commonly
impetigo with blisters caused by staphylococcal toxins
infants
whats the treatment for impetigo
topical antibiotics (fluclox) unless extremely widespread
remove crust with soap and water as that’s where the bacteria are
what is folliculitis
primary infection centered around hair follicles presenting with pustules and inflammation
what tends to cause folliculitis
s.aureus
whats the treatment for folliculitis
topical fusidic acid/mupirocin, if required short course oral fluclox
recurrent/severe = 3 months tetracycline
screen for nasal carriage
whats the treatment for an infected ulcer
potassium permanganate baths
optimise ulcer factors
oral antibiotics - depends on swabs/culture but pseudomonas common so penicillin/cipro useful
whats cellulitis
infection of subcutaneous tissue causing unilateral redness/swelling
whats the treatment for cellulitis
systemic antibiotics - fluclox clarithromycin/doxycycline if pen allergic, co-amoxiclav if on face
What commonly presents alongside cellulititis
tinea pedis, as it provides a port of entry
what is erysipelas
variant of cellulitis caused by group A streptococcus
where is erysipelas usually found
anywhere but the trunk
whats the treatment for erysipelas
Pen V
what is ecthyma
deep streptococcal infection causing indurated lesions with a crust - usually covering an ulcer
who gets ecthyma most commonly
immunocompromised/diabetics
whats the treatment for ecthyma
2-4 week course of systemic antibiotics (Pen V/fluclox)
what is staphylococcal scalded skin syndrome
rare condition following a staph infection due to toxin release, causes sheets of skin to shed leaving a raw erythematous layer
whats the treatment for staphylococcal scalded skin syndrome
- IV flucloxacillin
2. intensive care support, fluids, emollient etc
what is necrosing fasciitis
destructive, often fatal disease caused by a deep synergistic infection of staph and strep
dermatological emergency with exquisite tenderness, systemic sepsis and rapidly spreading erythema/necrosis
whats the treatment for necrosing fasciitis
Resus support
Systemic antibiotics - strongest
debridement of necrotic material
what are the common mycobacterium that cause issues dermatologically
M.tuberculosis + M.leprae
what dermatological issues do mycobacterium cause
lupus vulgaris
tuberculoid leprosy
lepromatous leprosy
what is lupus vulgaris
cutaneous m.tuberclosis infection causing reddish brown nodules that slowly enlarge to form a plaque commonly on face/neck
what’s the treatment for lupus vulgaris
same as pulmonary Tb (rifampicin,izoniazid, ethambutol, pyrazinamide)
what is tuberculoid leprosy
M.leprae infection causing thickened nerves and hypopigmented anaesthetic patches of skin
whats the treatment for tuberculoid leprosy
rifampicin/dapsone for 6 months
what is lepromatous leprosy
m.leprae infection causing symmetrical nodules papules and plaques
what does lepromatous leprosy lead to if untreated
leonine facies - facial disfigurement involving severe coarsening of the facial features
whats the treatment for lepromatous leprosy
rifampicin, dapsone and clofazimine for at least 2 years
what are the two types of herpes infection
1 = lips
2 =genitalia
however there is some crossover
what is the most common Herpes simplex virus infection in children
gingivostomatitis
what is gingivostomatitis
vesicular lesions on gum, lips and hard palate from herpes simplex infection causing fevers
whats the treatment for gingivostomatitis
topical/systemic aciclovir
what is eczema herpeticum
HSV infection of eczema causing crusted monomorphic vesicles and severe systemic unwellness
whats the treatment of eczema herpeticum
topical steroids + systemic aciclovir
check for impetigo and if there use topical Abx
what is varicella zoster virus infection also known as
chickenpox
how does varicella zoster virus infection present
children - extremely pruitic cropsof vesicles with crusting
adults - same as kids but may have internal organ involvement
what is shingles
reactivation of herpres zoster virus causing a cluster of vesicles in a dermatomal distribution
what does a shingles outbreak on the tip of the nose indicate
increased chance of eye involvement causing permanent blindness
what are complications of shingles infection
blindness from eye involvement
secondary bacterial infection
encephalitis
post-herpetic neuralgia
whats the treatment for shingles
aciclovir - only if new vesicles are forming
analgesia
what is molluscum contagiousm
asymptomatic lesion caused by a pox virus, presents as a self limiting wart-like round protrusion with a central dimple
what is the treatment for molluscum contagiosum
no treatment required
