Skin infections and infestations

Question 1

How do HSV-1 and HSV-2 infections differ in manifestation?

Answer 1

HSV-1 is traditionally associated with orofacial infection, while HSV-2 is traditionally associated with genital infection, although there is considerable overlap in disease manifestations.

Question 2

In what % of cases is primary infection of HSV asymptomatic?

Answer 2

80% of cases

Question 3

Describe latency in HSV infections of both orofacial infections and genital infections

Answer 3

Latency is the establishment and maintenance of latent infection in nerve cell ganglia proximal to the site of infection:
o In orofacial infection the trigeminal ganglia are most commonly involved
o In genital infection the sacral nerve root ganglia (S2-S5) are involved

Question 4

How do primary and secondary HSV infections differ?

Answer 4

Primary HSV infections are accompanied by systemic signs, longer duration of symptoms, and higher rate of complications. Recurrent episodes are milder and shorter

Question 5

What is the most common presentation of HSV-1 infections?

Answer 5

Herpetic gingivostomatitis

Question 6

When do most cases of herpetic gingivostomatitis occur?

Answer 6

Most cases arise between the ages of six months to five years

Question 7

What are the clinical features of herpetic gingivostomatitis?

Answer 7

Clinical features include:

• systemic upset
• lymphadenopathy
• gingivitis
• painful, white vesicles on tongue, buccal mucosa, palate, pharynx and lips

Question 8

How long do the symptoms of herpetic gingivostomatitis persist?

Answer 8

The main symptoms persist for 5-7 days, and are fully resolved within two weeks

Question 9

What is the proper name for cold sores?

Answer 9

Herpes labialis

Question 10

What does recurrent infections of orofacial herpes simplex infections usually present as?

Answer 10

Herpes labialis (syn. cold sore)

Question 11

What triggers Herpes labialis (syn. cold sore)?

Answer 11

Triggers are many, including UV-radiation, minor trauma and stress

Question 12

Describe the clinical presentation of Herpes labialis

Answer 12

The clinical presentation of a cold sore is that of grouped vesicles, especially of the lips and perioral skin. The eruption is often preceded by a tingling, itching or burning sensation. Over a few days the vesicles form a crust, and the eruption resolves within 7-10 days

Question 13

What can cause herpes genitalis?

Answer 13

Can be caused by both HSV-1 and HSV-2, and is usually sexually transmitted

Question 14

Which HSV virus is more commonly associated with recurrent herpes genitalis?

Answer 14

HSV-2

Question 15

How can herpes genitalis present in both men and women?

Answer 15

Systemic symptoms may precede the development of painful ulcers in both men and women

In women, ulcers can affect the external genitalia, as well as the vagina and cervix, which is involved in 70%-90% of cases. Dysuria may be severe and can cause urinary retention

In men, ulcers are most commonly seen on the glans, prepuce and shaft of the penis. Occasionally they can extend on to the scrotum, thighs, and buttocks. Approximately one-third of men will develop a urethritis

The perianal area and rectum may be involved with anal intercourse

Question 16

What % of cases in women with herpes genitalis have their vaginas and cervixes affected?

Answer 16

70-90% of cases

Question 17

Describe Inoculation herpes simplex

Answer 17

HSV can enter through an abrasion (e.g. shaving), to affect any part of the skin e.g. face, vulva etc

Lesions arise as vesicles, and sometimes bullae, either grouped as a plaque or scattered. Systemic upset tends to be minimal

Some well-described sites include the fingertips (a herpetic whitlow), where episodes can be recurrent, and on the face of rugby players, which is referred to as ‘scrumpox’

Question 18

What are some more unusual presentations of HSV infections?

Answer 18

• Keratoconjunctivitis
• Eczema herpeticum
• Neonatal herpes simplex
• Disseminated herpes simplex
• Erythema multiforme

Question 19

Describe keratoconjunctivitis

Answer 19

As with herpes zoster, a primary herpes simplex infection can lead to severe inflammation with the potential for damage to the cornea and conjunctivitis and blindness in the affected eye

Question 20

Describe Eczema herpeticum

Answer 20

Atopic patients are at risk of developing extensive eruptions of herpes simplex known as eczema herpeticum

The condition presents with clusters of itchy or painful vesicles / punched-out monomorphic erosions, which may coalesce

Any site can be affected, most commonly the face and neck. Lesions can occur in normal skin or in sites actively or previously affected by atopic eczema or other skin conditions

New patches form and spread over a period of 7 to 10 days, and can become widespread

Question 21

Describe neonatal herpes simplex

Answer 21

Genital herpes simplex at the time of delivery makes the risk of neonatal infection very high

Infection can also arise in the neonatal period

Symptoms vary from a localised cutaneous infection to disseminated herpes simplex

Question 22

Describe disseminated herpes simplex

Answer 22

Those at risk are immunocompromised patients (e.g. those on chemotherapy), and neonates not protected by maternally acquired antibodies. It rarely occurs in healthy individuals

Cutaneous lesions may be clinically indistinguishable from those of herpes zoster

Systemic infection, such as hepatitis and encephalitis may develop with or without widespread cutaneous lesions.

Question 23

Why is it important to distinguish early on between disseminated herpes simplex and disseminated herpes zoster?

Answer 23

The mortality from disseminated HSV is higher than that from disseminated zoster, so early recognition and treatment is essential

Question 24

Describe Erythema multiforme (EM)

Answer 24

• Is characterised by macular, papular or urticated lesions, as well as the classical ‘target lesions’ distributed preferentially on the distal extremities. Mucosal surfaces may be involved
• EM is a hypersensitivity reaction usually triggered by infections, most commonly herpes simplex. The infection may present as a cold sore, or may be subclinical

Question 25

How is primary herpetic gingivostomatitis and herpes genitalis treated?

Answer 25

Consider treatment with oral aciclovir 200 mg five times daily for 5 days. Adjust the dose accordingly in children

Alternatively use valaciclovir or famciclovir

Treatment will shorten the duration of an attack but does not prevent future attacks

In addition, for herpes genitalis, patients and their partners need screening for other sexually transmitted disease

Question 26

How is recurrent herpes labialis treated?

Answer 26

Reduce risk factors eg advise on appropriate UV-protection

5% aciclovir cream can be helpful if used as soon as patients are aware that a recurrence is occuring

For very frequent / distressing attacks consider prophylactic aciclovir 200-400 mg BD (alternatively use valaciclovir or famciclovir)

Question 27

How is recurrent herpes genitalis treated?

Answer 27

Treat with prophylactic aciclovir 400 mg BD (alternatively use valaciclovir or famciclovir)

Question 28

How is recurrent herpes simplex associated with recurrent erythema multiforme treated?

Answer 28

Treat with prophylactic aciclovir 400 mg BD (alternatively use valaciclovir or famciclovir), adjust the dose accordingly in children

Question 29

What is important to educate a HSV patient on for long term control and treatment?

Answer 29

It is important to recognise potentially life-threatening systemic infections, which are much more likely in immunocompromised patients and neonates

Patients need admitting urgently for treatment with high-dose intravenous antiviral therapy

Question 30

Who is most commonly affected by herpes zoster?

Answer 30

Herpes zoster is more common in adults, especially the elderly, the unwell, and the immunosuppressed

Not uncommon in kids, but generally quite mild

Question 31

What is usually the first manifestation of herpes zoster?

Answer 31

Pain, which may be severe, and may be accompanied by fever, headache and malaise

Question 32

How long is there between the start of pain and the onset of skin eruption in both trigeminal and thoracic herpes zoster?

Answer 32

The time between the start of the pain and the onset of the skin eruption averages 1.4 days in trigeminal zoster and 3.2 days in thoracic disease

Question 33

Describe the clinical features of herpes zoster infections

Answer 33

Dermatomal distribution of closely grouped red papules, rapidly becoming vesicular and then pustular, develop in a continuous or interrupted band in the area of one or occasionally two and, rarely, more contiguous dermatomes

New vesicles continue to appear for several days

In some patients lesions become much larger and necrotic

Question 34

What dermatomes are affected by herpes zoster?

Answer 34

o Thoracic 53%
o Cervical 20%
o Trigeminal, including ophthalmic 15%
o Lumbosacral 11%

Question 35

Describe herpes zoster oticus and the Ramsay-Hunt syndrome

Answer 35

Peripheral facial nerve palsy accompanied by an erythematous vesicular rash on the ear (herpes zoster oticus) or in the mouth

Is caused by varicella zoster virus (VZV) infection of the head and neck involving the facial nerve (seventh cranial nerve).

Question 36

Describe herpes zoster ophthalmicus

Answer 36

Skin lesions are located in the dermatome of the nasociliary nerve. This area includes not only the tip of the nose, but also involves the skin at the inner corner of the eye, and the root and side of the nose (Hutchinson’s sign)

Contact ophthalmologist ASAP to ensure sight isn’t affected

Question 37

Describe disseminated herpes zoster and who is mainly affected

Answer 37

The risk of cutaneous dissemination, which has been defined as more than 20 vesicles outside the area of the primary and adjacent dermatomes, increases with age

Life-threatening systemic dissemination is rare, and mainly affects patients with lymphoma and other immunocompromised conditions

Question 38

What is Hutchinsons sign?

Answer 38

Vesicles on the tip of the nose, or vesicles on the side of the nose, precedes the development of ophthalmic herpes zoster. This occurs because the nasociliary branch of the trigeminal nerve innervates both the cornea and the lateral dorsum of the nose as well as the tip of the nose

Question 39

What is postherpetic neuralgia?

Answer 39

o Is defined as the persistence or recurrence of pain more than one month after the onset of herpes zoster
o It becomes increasingly common with age, affecting about one-third of patients aged over 40. It is particularly likely if there is facial involvement
o The pain may be continuous and burning with increased sensitivity in the affected areas or a spasmodic shooting type of pain. Some patients complain of an itch and a crawling sensation. The overlying skin can be numb or exquisitely sensitive to touch

Question 40

What is standard treatment of herpes zoster virus?

Answer 40

Adults - oral antiviral therapy e.g. aciclovir tablets, 800 mg five times a day for seven days

Children - in healthy children the condition is often relatively mild and may not require treatment, however, children who take courses of systemic steroids, e.g. for asthma, are rendered vulnerable for up to three months after treatment is complete - if the child develops chickenpox in this period parents should seek urgent competent advice as treatment with oral antiviral therapy will be required

Question 41

Who should be closely monitored while on herpes zoster treatment?

Answer 41

Children who take courses of systemic steroids, e.g. for asthma, are rendered vulnerable for up to three months after treatment is complete - if the child develops chickenpox in this period parents should seek urgent competent advice as treatment with oral antiviral therapy will be required

Question 42

How is herpes zoster treated in immunocompromised patients?

Answer 42

Should continue on with oral antiviral therapy for two days after crusting of the lesions

If the patient is unwell / develops widespread (disseminated) zoster, admission will be needed

Question 43

How is ophthalmic zoster treated?

Answer 43

All patients with ophthalmic zoster, irrespective of age or severity of symptoms, should be prescribed oral antiviral drugs at the first sign of disease

Patients with a red eye or visual complaints must be referred to an ophthalmologist on an urgent basis

Those not needing referral must be reviewed after at most one week

Question 44

How is herpes zoster with Ramsay Hunt syndrome treated?

Answer 44

Oral antiviral therapy must be started immediately and contact the on-call ENT team

Some advocate the use of systemic steroids - refer to local guidelines for management

Question 45

How is postherpatic neuralgia treated?

Answer 45

Tricyclic antidepressants such as amitriptyline, or anticonvulsants such as gabapentin, are the mainstay of treatment

Question 46

What is impetigo?

Answer 46

Impetigo is a highly contagious bacterial skin infection causing blisters and sores. Impetigo mainly affects children, often on the face, especially around the nose and mouth, and sometimes on the arms or legs. The two types of impetigo are bullous impetigo and non-bullous impetigo

Question 47

Describe the pathogens that cause both non-bullous and bullous impetigo

Answer 47

Impetigo - in the UK Staphylococcus aureus is the most common organism, Streptococcus pyogenes is the other pathogen involved, and on occasions both organisms can be found together. In warmer climates Streptococcus pyogenes is more prevalent

Bullous impetigo - is nearly always caused by Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly common cause of impetigo, and is associated more often with the non-bullous form

Question 48

Who is most commonly affected by both non-bullous and bollous impetigo?

Answer 48

Although impetigo can affect any age, the non-bullous form is most common in children 2-5 years of age, and bullous impetigo under the age of 2 years

Question 49

What investigations are carried out for impetigo?

Answer 49

• Impetigo is usually diagnosed on the basis of the clinical appearance
• Poorly responsive or recurrent cases of impetigo should be swabbed for C&S to identify possible methicillin-resistant Staphylococcus aureus (MRSA). Swabs are best taken from a moist lesion, or, in cases of bullous impetigo from a de-roofed blister

Question 50

What general measures are taken to treat impetigo?

Answer 50

o Provide a patient information leaflet on impetigo
o Cover affected areas where possible
o Wash hands regularly
o Use separate towels and flannels
o Avoid school until the lesions are healed or crusted over, or 48 hours after antibiotics are started

Question 51

How is local/mild impetigo treated?

Answer 51

o First-line treatment is topical fusidic acid for 7-10 days

o In cases of fusidic acid resistance, use topical mupirocin

Question 52

How is widespread impetigo treated?

Answer 52

Use a systemic antibiotic for 7 days, either flucloxacillin or erythromycin / clarithromycin. Reasons for choosing the latter include cases of penicillin allergy, or if there are concerns with regards to compliance with flucloxacillin given its unpleasant taste and QDS dosing regime

Question 53

How is persistent or recurrent impetigo treated?

Answer 53

The nose is one of the most common sites of carriage for Staphylococcus aureus, so treatment of recurrent cases should include the application of nasal mupirocin up both nostrils BD for 5 days

Wash the whole body daily with antibacterial emollient, eg the Dermol range, or anti-septic, eg chlorhexidine

Consider a prolonged course of oral antibiotics for up to six weeks

Identify and treat other carriers and possible sources of re-infection - it may be useful to take nasal swabs from other household contacts even if they do not have any cutaneous symptoms

Question 54

If strep. causes impetigo, what could be a possible complication?

Answer 54

Streptococcal infection occasionally causes acute glomerulonephritis

Question 55

What is folliculitis and what is the common causative agent?

Answer 55

Folliculitis is a common skin condition in which hair follicles become inflamed. It’s usually caused by a bacterial or fungal infection. At first it may look like small red bumps or white-headed pimples around hair follicles.

Commonly associated with Staph infections

Question 56

What is a carbuncle and what is the common causative agent?

Answer 56

A carbuncle is a red, swollen, and painful cluster of boils that are connected to each other under the skin. 
A boil (or furuncle) is an infection of a hair follicle that has a small collection of pus (called an abscess) under the skin

Commonly caused by Staph infections

Question 57

Describe Erysipelas

Answer 57

Erysipelas is an acute infection typically with a skin rash, usually on any of the legs and toes, face, arms, and fingers. It is an infection of the upper dermis and superficial lymphatics, usually caused by beta-hemolytic group A Streptococcus bacteria on scratches or otherwise infected areas

Erysipelas is more superficial than cellulitis, and is typically more raised and demarcated

Question 58

Wha is the most common cause of erysipelas

Answer 58

Usually caused by beta-hemolytic group A Streptococcus bacteria on scratches or otherwise infected areas

Question 59

Describe cellulitis

Answer 59

Cellulitis is a bacterial infection involving the inner layers of the skin. It specifically affects the dermis and subcutaneous fat. Signs and symptoms include an area of redness which increases in size over a few days. The borders of the area of redness are generally not sharp and the skin may be swollen. While the redness often turns white when pressure is applied, this is not always the case. The area of infection is usually painful. Lymphatic vessels may occasionally be involved, and the person may have a fever and feel tired.

Question 60

What is the causative agent of scabies?

Answer 60

Human scabies is caused by infection with a mite known as Sarcoptes scabiei var. hominis.

Question 61

Describe scabies

Answer 61

Itch, which is characteristically worse at night

Scabies should be part of the differential diagnosis of any itchy rash where no other cause can be readily identified. It is possible for patients with eczema to also acquire scabies

Question 62

Where is mostly affected on the body by scabies?

Answer 62

The trunk and limbs are the predominant sites that are affected

The face and scalp are rarely involved other than in infants and bed-bound elderly patients

Question 63

Describe the morphology of scabies

Answer 63

A generalised rash with erythema, papular and urticated lesions. This is caused by an allergy to the mites and their products, and may take several weeks to develop after infestation

Burrows - are seen as very small irregular tracks. These are most common on the sides of fingers, the webs, the borders of the hands, the wrists and the feet. They can also be found on the male genitalia, axillae and buttocks

Papules and nodules - most commonly seen on the shaft of the penis (pathognomonic), the groins and in the axillae. They may persist for several weeks after the scabies has been eradicated

Papules and pustules on the palms and soles are characteristic of scabies in infancy

Question 64

What is crusted scabies?

Answer 64

Crusted scabies (syn. Norwegian scabies) is an uncommon form of scabies which is highly contagious.

It most commonly arises in patients with the following:
• Dementia
• Down’s syndrome
• Conditions associated with neurological impairment
• Immunosuppression
• Those who have been inappropriately treated with potent or super-potent topical steroids

Clinical features - generalised scaly rash. The itch is often significantly less than with classical scabies. The scalp may be involved

Question 65

In which groups is crusted scabies most commonly seen in?

Answer 65

It most commonly arises in patients with the following:
• Dementia
• Down’s syndrome
• Conditions associated with neurological impairment
• Immunosuppression
• Those who have been inappropriately treated with potent or super-potent topical steroids

Question 66

How is scabies treated?

Answer 66

5% permethrin cream (Lyclear ®) is the treatment of choice and is safe to use in pregnancy; other scabicides are more irritant and less effective. 1 x 30 g tube should cover an average adult

The cream should be applied uniformly over all the body from the neck downwards. Every inch of skin must be covered with special attention paid to skin creases, the genitalia and underneath the nails. The face and scalp should only be treated if they are affected, which is uncommon in adults and older children - Lyclear ® cream rinse should be used for the scalp

Wash off after 8 to 24 hours (note the cream should be re-applied to the hands if they are washed within 8 hours of first applying the cream)

Repeat treatment after seven days

Treat secondary infection if present with a systemic antibiotic e.g. flucloxacillin, or erythromycin if the patient is allergic to penicillin

Question 67

How are patient contacts of those who have scabies treated?

Answer 67

This includes anyone living in the same house, partners and others who have significant contact though child care eg in some situations grandparents

Remember other contacts can be infected with scabies but remain asymptomatic for several weeks

All such contacts need to be managed in exactly the same way as the patient, however for most only one treatment is needed. Only symptomatic contacts require two treatments

Question 68

How should persistent symptoms of scabies be treated?

Answer 68

The itch of scabies may not clear for at least a month after successful eradication of the mite. Treatment with Eurax HC ® cream helps reduce itch and it also acts as a mild scabicide.

Nodules, which are not contagious, can occasionally persist for several months and should be treated with a moderately potent topical steroid

Question 69

How is severe or crusted scabies treated?

Answer 69

Patients need frequent applications of permethrin, sometimes for several weeks. Oral ivermectin is sometimes used in such cases

Question 70

When should a discussion/referral to a dermatologist be considered in scabies cases?

Answer 70

o Diagnostic uncertainty / failure to respond to adequate treatment of the patient and contacts
o Crusted scabies
o An outbreak in a nursing or other care home