1. 13th April 2011 Dr Samantha Triggs GPVTS ST2
Skin Infections
13th April 2011
Dr Samantha Triggs GPVTS ST2

2. Bacterial skin infections
Viral skin infections
Fungal skin infections

3. Bacterial skin infections

4. Why does skin get infected?
There are multiple types of bacteria which are normally present on the skin.
For example: Staphylococcus epidermidis and yeasts
The presence of bacteria does not automatically lead to a skin infection
What is the difference between colonisation and infections???

5. Colonisation: Bacteria are present, but causing no harm
Infection: Bacteria are present and causing harm.
A break in the epidermal integrity can allow organisms to enter and become pathogenic. This can occur as a result of trauma, ulceration, fungal infection, skin disease such as eczema
The stratum corneum of the epidermis is important in maintaining a barrier against skin infections

6. Case History 1
A mother brings 5 yr old Johnny to surgery. He has developed this rash, which is weeping and crusting.

7. What is the diagnosis?

8. Impetigo
A highly infectious skin disease, which commonly occurs in children.

9. What is the likely causative organism?

10. The causative organism is usually Staphylococcus Aureus (>90% cases1), but less often can be strep pyogenes.
Begins as a vesicle, which may enlarge into a bulla.
Weeping, exudative area with characteristic honey coloured or golden, gummy crusts, which leave denuded red areas when removed.
May present as macules, vesicles, bullae or pustules
Bullae are more prominent in staphylococcal infection and in infants

11. What is the treatment?

12. Impetigo
Treatment:
Mild localised cases - use topical antibiotic Polyfax
Widespread or more severe infections – use systemic antibiotics, such as flucloxacillin (or erythromycin if penicillin allergic)
Up to 10 days if needed. NB if the primary skin problem is not treated, the infection may not settle eg underlying eczema needs treating as well

13. Johnny’s mum asks if Johnny has to have any time of off school
Johnny’s mum asks if Johnny has to have any time of off school. What should you tell her?
A: He does not have to be excluded from school so long as he is on antibiotics
B: He has to remain off of school for 5 days from the onset of the lesions
C: He must remain off of school until the lesions have crusted or healed
D: He must remain off of school until he has completed the antibiotic course.

14. Case History 2
A 27 year old business man attends surgery complaining of pain and itching in the beard area. You examine him and see the following:

15. What is the Diagnosis?

16. Folliculitis Inflammation of the hair follicle.
Presents as itchy or tender papules and pustules at the follicular openings.
Complications include abscess formation and cavernous sinus thrombosis if upper lip, nose or eye affected.
Sycosis Barbae is a variant which occurs in the beard area, ofen spread by shaving. Pseudofollicultis is not an infection, but an inflammatory condition caused by ingrowing hairs.

17. What is the causative organism?

18. Most common cause is Staph Aureus.
Other organisms to consider include:
Gram negative bacteria – usually in patients with acne who are on broad spec antibiotics
Pseudomonas (“Hot tub folliculitis”)
Yeasts (candida and pityrosporum)
Hot tub – typically occurs 1-4 days after bathing in unchlorinated contaminated water

19. What is the treatment?

20. Folliculitis treatment
Topical antiseptics such as Chlorhexidine
Topical antibiotics, such as Fusidic acid or Mupirocin
More resistant cases may need oral antibioics such as Flucloxacillin
Hot tub folliculitis – ciprofloxacin2
Gram negative – trimethoprim

21. Cellulitis Infection of the deep subcutaneous layer of the skin
Presents as a hot, tender area of confluent erythema of the skin
Can cause systemic infection with fever, headache and vomiting.
Erysipelas is more superficial and has a more well demarcated border
Treatement same and can coexist

22. Erysipelas

23. What is the most common causative organsism?

24. Cellulitis Streptococcus – Group A Strep Pyogenes.
Others include Group B, C, D strep, Staphylococcus Aureus, haemophilus influenzae (children) and anaerobic bacteria (e.g Pasteurella spp. After animal bites)

25. Treatment of cellulitis
Oral Flucloxacillin or erythromycin if allergic
Co-amoxiclav in facial cellulitis
If severe systemic upset, may require admission for IV antibiotics.
After the acute attack has settled, especially in recurrent episodes – consider the underlying cause

26. Orbital cellulitis – refer urgently

27. Case History 3
A mother phones the surgery about her 1 year old daughter Emma. Emma has been off her food and has had a slight runny nose. She has developed an erythematous rash. You arrange for her to attend the surgery for an appointment
When Emma is seen in the surgery, the rash has started to spread, now there is superficial blistering and parts of the epidermis can be seen to shear off after gentle pressure

28. Diagnosis???

29. Staphylococcal Scalded Skin Syndrome
A superficial blistering condition caused by exfoliative toxins of certain strains of Staph Aureus
Usually in children less than 5 yrs old
Characterised by blistering and desquamation of the skin and Nikolsky's sign (shearing of the epidermis with gentle pressure), even in areas that are not obviously affected
Does not involve mucos membranes like TENs or SJS do

30. begins with a prodrome of pyrexia and malaise, often with signs and symptoms of an upper respiratory tract infection
discrete erythematous areas then develop and rapidly enlarge and coalesce, leading to generalised erythema - often worse in the flexures with sparing of the mucous membranes
large, fragile bullae form in the erythematous areas and then rupture

31. Complications include hypothermia, dehydration and secondary infection.
Treatment: ABC, refer urgently for IV antibiotics and fluids, may need referral to tertiary burns centre

32. What is the diagnosis?
Painful red nodule

33. Furunculosis (boils) and carbuncles
Deeper Staphylococcal abscess of the hair follicle
Coalescence of boils leads to the formation of a carbuncle
Treatment is with systemic antibiotics and may need incision and drainage.
Consider looking for underlying causes, such as diabetes

34. What is the diagnosis? Case history 4
Mrs. Brown is a 78 yrs old type 2 diabetic.
Mr Brown phones the surgery to request a home visit for his wife. He tells you that Mrs Brown has been feeling unwell for a few days with a pyrexia and headache. She has a red area of skin on her lower leg which is intensely painful.
You arrange a home visit.
When you arrive, Mrs Brown is quite lethargic and confused.
Temp 39 degrees
HR 115 bpm
BP 90/50
You notice that the edge of the area starts to become purple.
Started as pain, pyrexia and cellulitis, later developed purple skin discolouration and became systemically unwell
What is the diagnosis?

36. Necrotising Fasciitis
Rare, but serious and fatal condition
Deep-seated infection of subcut fat and fascia which spreads along fascial planes. Vascular thrombosis leads to rapidly progressing infarction and death of skin and tissue, with systemic infection
If suspected – refer urgently

37. Case history 5
Mr Jones is a 22 year old who works as a personal trainer. He attends surgery as he wants to discuss his smelly feet!
He tells you he has developed lots of “holes” in the soles of his feet.

38. What is the diagnosis?

39. Pitted Keratolysis
Caused by Cornebacteria, which colonise the surface stratum corneum and produce areas of sharply demarcated maceration.
Later develops a characteristic pitted appearance.
Smells like rotten fish
More common in young males, who wear tight occlusive shoes
Treatment is aimed at reducing sweating and reducing bacterial colonisation:
Breathable footwear
Topical antibiotics (fusidin or mupirocin)
Potassium permanganate, 20% aluminium chloride hexahydrate or 4% formaldehyde soaks can be affective

40. Case History 6
Mr Smith is 40 yrs old who has a rash in his axilla.

41. You are fortunate enough to have a wood’s light available in the room in your training practice!
When you use the Wood’s light, the skin lesion shows a dramatic coral pink fluorescence.

42. Erythrasma
Colonisation of axillae or groin with Cornebacterium Minutissimum.
Presents as a fine, reddish brown rash in the flexures, which is confluent and sharply marginated.
Often misdiagnosed as a fungal infection
Woods light illumination produces a characteristic coral-pink fluorescence.
Treatment is with topical fusidin cream

43. Viral Skin Infections

44. Viral warts and verrucas
Caused by human papilloma virus
Very common
Disappear spontaneously eventually
If treatment is needed, options include:
Salicylic acid topically – needs daily treatment and can take months
Duct tape occlusion
Cryotherapy

45. Case history 7
A father brings his 3year old Daughter “Sarah” to surgery. She has developed an itchy rash:

46. Diagnosis?

47. Molluscum Contagiosum
Which one of the following statements regarding this condition is incorrect?
A: Usually spontaneously resolves
B: Caused by an RNA pox virus
C: Transmission is by direct contact
D: There is no need for school exclusion
E: Lesions usually heal without scarring

48. Molluscum contagiosum
Caused by DNA pox virus
Common in children, but can occur at any age
Spread by direct contact
Presents as multiple small, pearly, dome-shaped papules with central umbilication
Can occur at any site
Usually resolve spontaneously in 6-18 months
Resolution is heralded by the development of erythema around the lesions.
Treatment is not usually necessary – simple reassurance and advice about reducing transmission.
If treatment is necessary, options include:
Piercing the lesion with an orange stick tipped with iodine
Curretage
imiquimod cream

49. Herpes Zoster (Shingles )
Caused by reactivation of the chickenpox virus which has lain dormant in the dorsal root or cranial nerve ganglia
Rash is preceded by a prodromal phase of up to 5 days of tingling or pain
Then develop painful vesicles in a dermatomal distribution. Most common in thoracic and trigeminal areas
Lesions become purulent, then crusted
Healing takes place in 3-4 weeks

50. Regarding infectivity and shingles: true or false?
1. Children with shingles should remain off school from 5 days from the onset of rash
2. Shingles in a pregnant mother does not carry a risk of her own fetus developing fetal varicella syndrome.
3. You can catch shingles from another person who has shingles
4. If not immune, you can catch Chicken Pox after contact with shingles
HPa advise no school exclusion needed so long as rash is covered and not weeping.

51. Shingles treatment Aciclovir 800mg 5 times daily, for 7 days
Rest, analgesia
Complications include:
Post herpetic neuralgia
Secondary infection
Guillain Barre Syndrome
Occular disease
Reduces duration of rasha nd reduces pain. Should be started within 72 hours of onset. Id opthalmic nerve involved. Need opthalmic opionin in trigeminal, esp if lesions on the side and tip of the nose.

52. Post-herpetic Neuralgia
= pain lasting longer than 3 months after the rash.
Which of the following is NOT a risk factor for developing post-herpetic neuralgia?
A: Younger age
B: More severe pain
C: Severe rash
D: Prodromal pain in dermatome
Risk reduced by antgi-viral agents at the start of the rash. Treatments include amitriptyline, pregabalin as per NICe guidelines on neuropathic pain management

53. Herpes Simplex Virus True or false:
HSV 1 is commonly sexually transmitted
The correct dose of aciclovir for HSV is 200mg 5 times daily for 5 days
Caesarean section should be recommended to all women presenting with primary episode genital herpes lesions at the time of delivery
Caesarean section is routinely recommended for women with recurrent genital herpes lesions at the onset of labour.
F, T, T, F (RC0G advise small rosik to baby if recurrent infection and so not routinely recommend CS

54. Herpes Simplex Virus
A highly contagious infection spread by direct contact
HSV 1 = common coldsore
HSV 2 usually presents on the genitalia
Primary infection presents as acute, painful gingivo-stomatitis with multiple small intra-oral ulcers. Associated with fever, malaise and lymphadenopathy.
Attacks are usually self-limiting
Topical aciclovir can be used for oral lesions: 5 times daily for 5 days. Reduces duration of attack and duration of viral shedding.
NB orogential contact can result in HSV 1 in the genital area.

55. Types: Genital herpes Herpetic Whitlow Eczema Herpeticum
Herpes Simplex Keratitis

56. Fungal Infections

57. Diagnosis?
Itchy rash

58. Dermatophyte infections
3 main genera:
Trichophyton
Microsporum
Epidermophyton
Invade the keratin of the stratum corneum
Can be:
Anthopophilic – contracted from humans
Zoophilic – contracted from animals
Geographic – contracted from soil
Clinical appearance depends on the organism involved, the site and the host reaction

59. Name the fungus!!!

60. Tinea Corporis - Presents as scaly erythematous plaques with central clearing

61. Tinea Cruris – commoner in males, assymmetrical erythema spreading from groin to upper thigh. Scaly advancing edge.

62. Tinea Pedis: 2 main presentations:
- Moist scaling between the toes, esp 4/5 webspace.
- Mocassin type – fine, dry diffuse scaling over the whole sole.

63. Tinea Manuum – diffuse dry scaling over the palm

64. Tinea Capitis – commonest in children
Tinea Capitis – commonest in children. Presents as non-itchy patches of hair loss with broken hairs.

65. Tinea Unguium – Different presentation including:
- White Onchomycosis
- Oncholysis
- Sub-ungural hyperkeratosis
- Thickening of nail plate

66. Case History 8
A 22 year old lady returns from a holiday in Spain. She has a tan. She has noticed hypopigmented lesions on her chest and back.

67. Choose the diagnosis from the list below
Tinea Corporis
Lyme’s Disease
Psoriasis
Pityriasis Versicolor
Vitiligo

68. Pityriasis Versicolor
Common in young adults
Occurs when the commensal follicular yeast Pityrosporum Orbiculare transforms into a mycelial form.
Presents as fine, reddish-brown, scaly eruptions which are asymptomatic.
Once the rash has gone, it leaves hypopigmented macules which fail to tan
Treat with topical imidazole cream if fine scaling present
Takes 1-2 yrs for repigmentation

69. Candida
A commensal organism which becomes pathogenic under certain circumstances:
With broad spec antibiotic use
Pregnancy
Immuno-compromise and diabetes
Moist skin folds and areas of damp skin
Can present at various sites, including orally, in genitals, groin, under breasts
Management:
drying affected area,removing causative factors.
topical antifungal creams

70. Any Questions????

71. References Kumar and Clark: clinical medicine 5th Edition.
General Practice Notebook
RCOG Greentop guideline number 30: Genital Herpes in pregnancy
Practical General Practice