Short notes on skin and soft tissue infections

1. Skin and
Soft Tissue
Infections
Sanjaya Gihan Weerasinghe

2. • Infections in,
– Skin
– Subcutaneous tissue
– Fasciae
– Muscles

4. Erysipelas
• Strep. Infections of dermis
• Well demarcated, painful,
erythematous
• indurated plaques, Blisters &
ulceration 
• Abrupt fever with chills
• Face, legs
• common in very young, old,
debilitated patients
• lymphoedematous
• erysipelas and Cellulitis overlap
often
• Treatment: Penicillin IV/IM

5. Impetigo
• A contagious superficial infection of the skin
• Staphylococci or β-haemolytic streptococci
• common in children
• usually involves the skin of the face, often around the
mouth and nose.
• spread by direct contact
• Minor abrasions and other skin lesions predispose to
infections
• Prevention is by good personal hygiene , particularly
hand washing with soap.

6. • It has two forms:
1. Non-bullous
Streptococcus pyogenes
"honey-crust" lesions
2. Bullous
Staphylococcus aureus
rupture of the bullae
"varnish-like" crust

8. Treatment
• Usually self-limiting
• Avoid precipitating factor (e.g., exfoliation)
• Localized
– topical fusidic acid tds. (for MRSA)
• mild and localized – Topical antibiotic
e.g.; topical mupirocin
• Extensive disease
– oral flucloxacillin, Erythromycin

9. • Other close contacts should be examined
• children should avoid school for 1week after
starting therapy.
• resistant to treatment or recurrent
– take nasal swabs and check other family
members.
• Eradication of nasal carriage
– Nasal mupirocin

10. Folliculitis
• Infections of the
superficial part of the
hair follicle
• itchy or tender papules
and pustules.
• Staphylococcus aureus

11. • Small pustules often
pierced by a hair
• Legs, face – (sycosis
barbae)
• commoner in humid
climates and when
occlusive clothes are worn.
• Extensive, itchy folliculitis
in HIV infection.

12. Treatment
• topical antiseptics
• topical sodium fusidate
• mupirocin containing ointment
• oral antibiotics
– flucloxacillin or erythromycin
• If chronic – Detect and treat carrier state

13. Boils (furuncles)
• Staph. Infections of the deeper part of hair follicle
• most common on the face, neck, armpit, buttocks, and
thighs
• On central face
– danger of cavernous sinus thrombosis
• Tender, red, cone shaped swelling
• heal with scarring
• Recurrences may occur
• Exclude carrier state
• Treatment: Antibiotics
• If large – need incision

14. CARBUNCLE
• Deep staph. Infection of
several adjacent hair
follicle
• cluster of boils that form a
connected area of infection
• neck, back, thighs
• In diabetics & debilitated
• Treatment
– Antibiotics,
– Surgical incision

15. Ecthyma
• By both streptococci and
staphylococci
• Ulcer forms under a
crusted surface of the
infection
• Heals with scarring

16. • Poor hygiene and malnutrition are predisposing
factors
• Minor injuries and other skin conditions
determine the site
• Treatment-
– Improved hygiene and nutrition
– Antibiotics
(phenoxymethylpenicillin and flucloxacillin)

17. Cellulitis
• Infection of normal skin flora or exogenous
bacteria
(S. aureus and ß-haemolytic streptococci)
• Deep skin or subcutaneous layer
• Hx of Trauma and Ulceration
• Organisms enter through breach in skin
• Infection can spread to blood stream
Bacteremia /septicemia.
• lower leg , hand ,nose ,periorbital

18. Clinical features
• Acute localised pain
• Oedema
• lymphangitis
&lymphadenitis
– Hot painful erythema
streaking, progressing
proximally from the
affected area, tracking
along lymphatics
• +/- blister
• Fever, Malaise,
Leucocytosis

20. Predisposing factors
Diabetes
Alcoholism
Malignancy
Drug abuse
venous stasis
lymphoedema

22. Investigations
• Swabs taken from relevant sites (from leading
edge or aspirating blisters)
• Gram stain and Blood cultures
• Serological-
– antistreptolysin O titre (ASOT)
– antiDNAse B titre (ADB)

23. Management
• Elevate limb.
• Treat underlying Cause
• Antibiotics
– Phenoxymethylpenicillin
– erythromycin
– flucloxacillin (all 500 mg
qds)
– Vancomycin
– Linezolid
– Clindamycin
• Widespread
– IV antibiotics (3–5 days) ,2
weeks (oral)
• Recurrent
– low dose antibiotic
prophylaxis
(phenoxymethylpenicillin)
MRSA Cellulitis

24. Complications-Local
• Blisters
• Skin necrosis
• Thrombophlebetics
• Lymphadenitis
• Abscesses

25. Complications-Systemic
• Bacteremia
• Septicemia
• Osteomyelitis
• Meningitis

26. Skin abscess
• Subcutaneous
• localized collection
of pus
• surrounded by
granulation tissue
• Hx of
– penetrating injury
– infection of haematoma

27. Features:
Cellulitis present
Swollen
Soft center
feels like fluid
underneath
Painful
Tender
Cellulitis
Abscess
• S. aureus is the common infecting organism
• Poor hygiene is predisposing
• Rx- incision and drainage

28. Necrotizing fasciitis
• Surgical emergency
• Polymicrobial Infection of the fascia
Type 1- E.coli, Pseudomonas, Proteus, Bacteroides,
Clostridium
Type 2- Streptococcus
• May proceed rapidly to underlying muscle.
• Diagnosis is often delayed
• Primarily a clinical diagnosis
• Rapid progression to septic shock
• Mortality 30-50%

30. Clinical Features
• Severe pain at the site
of initial infection
• Tissue necrosis.
• spreading erythema
• pain
• soft tissue crepitus
– (infection tracks rapidly
along the tissue planes)
• Fever ,Tachycardia

31.  Diagnose on
signs and
symptoms.
 Imaging- air in
the tissues.

32. Clinical findings in necrotising fasciitis
Early findings
1. Pain
2. Cellulitis
3. Pyrexia
4. Tachycardia
5. Swelling
6. Skin anesthesia
Late findings
1. Severe pain
2. Skin discoloration (purple or
black)
3. Blistering
4. Hemorrhagic bullae
5. Crepitus
6. Discharge of “dishwater” fluid
7. Severe sepsis or systemic
inflammatory response syndrome
8. Multi-organ failure

33. • Treat aggressively and promptly
• antibiotics
–Type 1-
– Broad-spectrum combination
(amoxicillin , imipenem, levofloxacin)
–Type 2
• benzylpenicillin and clindamycin

34. • urgent surgical exploration
– Extensive debridement or
– amputation (if necessary)
Necrotizing fasciitis after debridement

35. •
Staphylococcal scalded skin syndrome
• exfoliate or epidermolytic
toxin.
• rapidly spreading tender
erythema
• Dermonecrosis
• Outer layer of the epidermis
peel off
• Blistering
• Ritter's Disease of the
Newborn - most severe form
of SSSS

36. • Affects
– infants, immunosuppressed , renal disease,
Malignancy
• Mortality – higher in adult
• Diagnosis
– Clinical
– Culture
– Frozen section examination of skin – shows split
• Treatment: IV antibiotics & nursing care
or Self limiting.

37. Hidradenitis suppurativa
• Infection in Apocrine sweat glands
• Common in Axillae and groin and in females
• Multiple tender swellings
• Enlarging and discharging pus
• Recurrence
• worse in obese individuals
• Rx-
– weight loss
– oral retinoids (Vitamin A)
– Zinc gluconate

38. Erythrasma
• Chronic skin infection of
Corynebacterium
• Macular wrinkled, slightly scaly pink
,brown or macerated white areas
• armpits ,groin or between toe webs
• Coral pink under Wood’s light
• prevalent among diabetics, the
obese, and in warm climates
• Rx – Topical fusidic acid ,Miconazole

39. Pyomyositis
• S. aureus & Streptococcus
infection of the skeletal
muscles
• pus-filled abscess
• most common
in tropical areas- “ myositis
tropicans”
• can affect any skeletal muscle
• most often infects the large
muscle groups
e.g.-quadriceps or gluteal
muscles

40. • Fever, Sepsis, Localized
inflammation
• Muscle pain
• Predisposing factors-
Immunodeficiency,
IVDAs, Trauma and
malnutrition
• Complications- Abscess,
sepsis
• Rx- Drain surgically and
antibiotics

41. Gangrene
• Clinical situation where extensive tissue
necrosis is complicated by bacterial infection
Dry gangrene
Wet gangrene
Gas gangrene
• Predisposing factors
– Serious injuries
– Ischemia due to atherosclerosis and PVD
– Diabetes

42. Dry Gangrene
• The result of
ischaemic coagulative
necrosis.
• Black, dry, sharply
demarcated
• Secondary bacterial
infection is insignificant
E.g. Gangrene of
extremities in
thrombo-embolic
occlusion of vessels

43. Wet Gangrene
• Tissue necrosis is complicated by severe infection.
• Swollen, reddish-black foul smelling tissue.
• Extensive liquefaction of dead tissue occurs due to
invasion of organisms & acute inflammation.
• No clear demarcation between dead and viable
tissue.
• Occurs in extremities and internal organs
E.g. Diabetic gangrene of foot
Gangrene of bowel

45. Gas Gangrene
(Clostridial myonecrosis)
• Clostridium perfringens
• Extensive tissue
destruction
• gas production by
fermentative action of
bacteria.
• Swollen reddish-black
foul smelling tissue
with crepitus.

46. Treatment
• usually surgical debridement
• amputation (if necessary)
• Antibiotics alone are not effective