Bacterial/viral infections

Question 1

What are the commensal organisms in the normal skin flora?

Answer 1

S. epidermis (staph)
Micrococci
Corynebacteria
Proprionibacteria 
S. aureus

Question 2

Which infections are causes by primary S. aureus?

Answer 2

Impetigo
Ecthyma
Folliculitis
Furunculosis
Carbuncle
Cellulitis

Question 3

What is the management for impetigo?

Answer 3

Topical antiseptics or antibiotics
Flucloxacillin for more extensive
Golden crust should be soaked off with soap and water, full of water

Question 4

What is the management for folliculitis?

Answer 4

Screen for nasal carriage and treat with mupirocin nasal ointment if positive
Topical antibiotics
Oral flucloxacillin
3 month course of tetracycline if severe

Question 5

How is bullous impetigo managed?

Answer 5

Blisters 2-3cm
Toxin produced by certain strains of S. aureus
Flucloxacillin or erythromycin

Question 6

How is staph scalded skin syndrome (SSS) managed?

Answer 6

Antibiotics
May require intensive care support 
Blood cultures are only rarely positive 
IV flucloxacillin or erythromycin 
Most cases resolve 7-14 days

Question 7

What is erysipelas?

Answer 7

Form of cellulits caused by streptococci
Beefy bolstered edge, painful
Treated with penicillin V

Question 8

How does scarlet fever present?

Answer 8

rash of tiny pinkish-red spots that cover the body
Strep throat or impetigo caused by group A strep
Sydden fever, sore throat, neck lymphadenopathy, headache, nausea, swollen and red strawberry tongue
rash appears 12-48 hours after the start of the fever. Peeling of the rash tends to happen at day 6 and may continue up to 6 weeks
Penicillin is prescibed for 10 days

Question 9

What is pitted keratolysis?

Answer 9

Caused by overgrowth of micrococci. Occurs with occlusive footwear and sweaty feet.
Treatment: better hygiene, topical antibiotic, and soaks with 0.01% potassium permanganate or 3% formaldehyde.

Question 10

What is erythrasma?

Answer 10

Overgrowth of corynebacteria This is usually asymptomatic.
Fluoresces coral-pink under Wood’s light.
Treatment: topical imidazole creams, fusidic acid or oral erythromycin.

Question 11

What are the types of warts?

Answer 11

Plantar Warts (HPV-1,2,4 or 57) occur on the soles of the feet and may produce discomfort due to pressure effects on the surrounding skin. They are more resistant to treatment than other warts.
Common Warts (HPV-2) are elevated papules often seen on the back of the hands of young children. They are usually multiple and may sometimes occur on the face.
Plane Warts (HPV-3) are flat-topped warts usually found on the face or back of the hands.
Filiform Warts are hyperkeratotic papillomatous warts that commonly occur on the eyelids, neck, face and body folds. Response to topical paints is poor and electrocautery +/- curettage is recommended.
Mosaic Warts are confluent crops of warts usually seen on the hands/feet. They are very resistant to all forms of therapy.
Anogenital Warts (HPV-6 & HPV-11)  may predispose to cervical neoplasia, all females should have cervical cytology performed. Referral to the genito-urinary for STI check

Question 12

How are topical paints used for warts?

Answer 12

As effective as cryotherapy if applied on a daily basis for 8-12 weeks. Most preparations contain a combination of salicyclic and lactic acid as keratolytic agents. They should be applied after a 5 minute soak in warm water and preferably after removal of excess keratin using an emery board or nail file (which are often included with the product).

Question 13

How is cryotherapy used for warts?

Answer 13

liquid nitrogen (-196ºC) can be effective if used as a double freeze-thaw cycle on three or more occasions. It should be applied to produce freezing of 1mm of surrounding skin, which will normally take 5-30 seconds. It can be very painful and commonly produces blistering.

Question 14

How is curettage and cautery used for warts?

Answer 14

Very effective method of treatment followed by haemostasis using silver nitrate or electrocautery. Local anaesthetic will be required and histology is necessary to confirm the diagnosis. Squamous cell carcinomas and melanomas may occasionally mimic cutaneous warts. Warts should never be excised since they frequently recur in the scar.

Question 15

How are formalin soaks and podophyllin used for warts?

Answer 15

Resistant warts may require 4% formalin soaks or 10-20% podophyllin (not in pregnancy). These should only be applied under careful supervision. Podophyllin is very effective for anogenital warts.

Question 16

How does molluscum cotangiousum present?

Answer 16

Molluscipox Virus Type 1 or Type II
Young infants and children (esp atopic dermatitis)
Small umbillicated papules on trunk
Inflammatory changes supervene due to the immune response which results in suppuration, crusting and intense erythema around individual lesions. Secondary infection may occur and rarely giant mollusca can be present.

Question 17

What is the treatment for molluscum contagiosum?

Answer 17

Lasts between 4-18 months (self limiting)
Contagious among children, doesn’t require treatment
Lesions in older patients can be treated with cryotherapy or topical podophyllin.

Question 18

What can trigger recurrent attacks in HSV 1?

Answer 18

Minor trauma, UV exposure, upper respiratory tract infection, surgery or dermabrasion

Question 19

How does varicella voster virus (chickenpox) present?

Answer 19

Transmitted in respiratory drops
Incubation is 14-17 days
Infective 2 days before and 5 days after eruption
Headache, fever malaise for 24-48 hours followed by vesicles on trunka nd scalp
Rash lasts 10-14 days with crusting and occasional scarring

Question 20

What are the complications of VCV?

Answer 20

Pregnancy: Chicken Pox occurring in the first 20 weeks of pregnancy is associated with a 2% risk of foetal damage including neurological, ocular and limb defects.
Pneumonia
Hepatitis
Encephalitis
Disseminated Infection: Fatalities may occur in patients taking oral prednisolone or those that are immunocompromised.

Question 21

What is the treatment for VCV?

Answer 21

Adults, immunocompromised or patients on prednisolone require oral aciclovir for 5-7 days.

Question 22

How does parapox virus present?

Answer 22

Widespread in lambs/goats
he initial incubation period is 5-6 days and is followed by the development of a small reddish-purple papule on the finger which often blisters. The lesion extends to become 2-3cm in diameter and may become secondarily affected.
It is a self-limiting disease lasting 2-3 weeks. Secondary infection may require oral Flucloxacillin.

Question 23

How does coxsackie virus present?

Answer 23

Infants and young children
erythematous vesicles affecting the mouth, palms of the hands and the soles of the feet
Lesions last 5-7 days
School epidemics occur
Diagnosis:
Characteristic distribution of vesicles on the hands and feet +/- oral lesions. Electron microscopy will demonstrate viral particles but this is rarely required.
Sel-limiting

Question 24

How does pityriasis rosea present?

Answer 24

herald patch which consists of an oval erythematous plaque with surface scaling 2-5 cm in size. This precedes a generalised eruption of multiple smaller well-defined erythematous macules on the trunk in 5-15 days after the herald patch. The macules have a distinctive outer edge of collarette scale. The patients are normally well. The generalised eruption on the trunk is usually symptomatic or mildly pruritic.
Diagnosed by Clinical history of herald patch (80% cases) + distinctive collarette scale.
Symptomatic cases treated with mild steroids or UVB