Bacterial and Parasitic infections Flashcards
1
Q
Impetigo
- definition
- etiopathogenesis
- risk factors
- clinical features
A
- acute, superficial bacterial skin infection.
- S. aureus (bullous and non-bullous), S. pyogenes (non-bullous only)
- children, warm climate, poor hygiene, skin lesions, chronic conditions (ex: atopic dermatitis)
- around the mouth or upper limb.
- single/multiple, irregular superficial plaques
- Non-bullous - pink macule –> vesicles or pustules –> honey crusts erosions
- Bullous - small vesicles –> flaccid transparent bullae
2
Q
Impetigo
- diagnosis
- treatment
- prevention
A
- anamnesis, clinical presentation, microscopy and culture
- clean the wound, antibiotics (1st line - mupirocin), cover infected areas
- avoid close contact to others, wash wound daily, use separate towels, change laundry and clothes
3
Q
- Bullous impetigo vs.
2. Non-bullous impetigo
A
- S. aureus exfoliative toxins targe desmogein 1 and cleave off the superficial epidermis through the granular layer
- S. aureus and S. pyogenes
4
Q
Folliculitis
- definition
- risk factors
- clinical features
- classification
A
- inflammation of hair follicle
- excessive sweating, chronic use of steroids, wet/humid, immunodeficiency, dry skin, male gender, occlusion/skin irritation
- pustules with erythematous border at the site of the hair follicle
- superficial - bacterial, fungal, viral, dermodex, ingrown hair, friction, follicular trauma or occlusion
- deep - furuncle
5
Q
Folliculitis
- diagnosis
- treatment
- prevention
A
- clinical signs, anamnesis, KOH microscopy (fungal), gram staining (bacterial), tzanck test (viral)
- topical or systemic treatment depending on the causative agent (ex: acyclovir - viral, ivermectin - dermodex, ketoconazalone - fungal, penicillins - bacterial)
- eliminate risk factors, hygiene, warm compress
6
Q
Cutaneous abscess - furuncle, carbuncle
- definition
- pathogenesis
- risk factors
- clinical features
A
- furuncle - infection involving hair follicle and surrounding tissue, carbuncle - cluster of furuncles, deeper, cutaneous abscess - local collection of pus
- trauma –> bacteria enter –> inflammatory cells –> tissue destruction + pus –> further inflammation
- hot/humid climates, obesity, immunosuppressed, occlusion/friction of skin, foreign bodies, elderly
- erythematous pustules/ nodules + hair follicle in the center, together with cellulitis/lymphadenopathy/leukocytosis/ fever, heals with scaring
7
Q
Cutaneous abscess - furuncle, carbuncle
- diagnosis
- treatment
- prevention
A
-Tzanck test, KOH, culture, microscopy
- topical: warm compresses, anti-septic, local antibiotics
- systemic: drugs against MRSA (vancomycin), abscess drainage, antibiotics
-avoid risk factors
8
Q
Erysipelas and Cellulitis
- definition
- pathogenesis
- risk factors
A
- E: acute inflammatory superficial form of cellulitis
- C: bacterial infection - affects dermis and subcutis
- Group A beta hemolytic streptococcus
- bacterial release virulence factors –> virulence factors invade the skin
-previous episodes, breaks in the skin, immunodeficiency, venous diseases, current or prior injury
9
Q
Erysipelas and Cellulitis
- diagnosis
- treatment
- prevention
A
-clinical findings, gram staining, ESR, CRP, leukocytosis
- cold packs and analgesics, elevate infected limb, antibiotics (penicillin), wound care with saline dressings
- vancomycin when the cause is MRSA
-avoid pathogen entry into skin
10
Q
Erysipelas and Cellulitis
-clinical features (5)
A
- usually located in the lower leg
- prodrome - fever, chillds, myalgias, malaise
- multiple/single erythemas
- hot, sharply demarcated, raised, tender borders
- cellulitis –> not that swollen because infection is deeper
11
Q
Lyme borreliosis
- definition
- pathogenesis
- diagnosis
A
- infection caused by borrelia burgdorferi (spread by ticks)
- tick bite –> organisms migrate around the skin –> spread via the lymphatics
- anamnesis, ELISA, immunofluorescence, skin biopsy, PCR
12
Q
Lyme borreliosis
- treatment
- prevention
A
- localized lyme disease: doxycline, amoxicillin (pregnant)
- disseminated lyme disease: ceftriaxone
-avoid exposure, protective clothing
13
Q
Lyme borreliosis
-clinical features
A
Stage 1: erythema migrans (papule/macule that gradually expands, >5cm), lymphocytoma (red/blue patch in earlobe, nipples, scrotum), influenza like symptoms, non-pruritic
Stage 2: neurologic problems (Bell’s palsy, meningitis, neuritis), cardiac problems (AV block), arthritis
Stage 3: neurologic problems (confusion, short-term memory loss, numbness), arthritis
Acrodermatitis chronic atrophicans - distal limbs
- inflammatory - reddish discolouration, swelling, tender and painful
- atrophic - atrophy of skin, glands, hair, dilation of blood vessels
14
Q
Scabies
- definition
- pathogenesis
- types (2)
A
- infection caused by mite in human-human contact
- several scabies infect host –> mating –> female mite secrete proteolytic enzymes that allow them to enter the skin –> 3 eggs each day –> after 2 months female mite dies –> larva mature –> vicious cycle
- excretion of mite + decomposing bodies = type 4 hypersensitivity = pruritus + excoriations
- classic and crusted scabies (special form - Norwegian scabies)
15
Q
Scabies
- diagnosis
- treatment
- prevention
A
- anamnesis, dermoscopy - burrows, skin scraping + histology (mites, eggs, feces of mites)
- scabicidal agent (permethrin 5%), oral ivermectin, oral antihistamines (pruritus), corticosteroids if severe
- wash all textiles
