Bacterial skin disorders can be caused by resident or pathogenic bacteria on the skin. Common bacterial skin infections include impetigo, bullous impetigo, ecthyma, folliculitis, furuncles, carbuncles, erysipelas, and cellulitis. Impetigo is usually caused by Staphylococcus aureus or Streptococcus pyogenes and presents as crusty sores that can spread. Bullous impetigo caused by S. aureus causes fluid-filled blisters in infants. Folliculitis is a bacterial infection of hair follicles that can be superficial or deep. Furuncles are painful, pus-filled bumps under the skin caused by infected hair follicles

1. Bacterial Skin Disorders
By:- Hely Parikh

2. Normal Skin Flora
Resident Flora
(Non- Pathogenic)
Resident Flora
(Pathogenic)
Staphylococcus Epidermitis Staphylococcus aureus
Corneybacterium Staphylococcus pyogens

3. Functions of Resident Flora
❏ Compete with pathogenic organisms for nutrients.
❏ Produce antibiotics and other chemicals which inhibit growth
of pathogens.
❏ Modify secretions of skin to make skin a less favorable habitat
for pathogens.

4. Bacterial Skin Infections
Pyodermas
Non-Follicular Follicular
Localized
● Impetigo
● Ecthyema
Spreading
● Erysipelas
● Cellulitis
Folliculitis
● Superficial
● Deep
Peri-Folliculitis
● Furuncle
● Carbuncle

5. Impetigo Contagiosa
Caused By
S. aureus (in developed countries)
S. pyogenes
Age: Preschool and young school children.
Gender: males > females.

6. Morphology
● Multiple lesions
● Thin-walled bulla on an erythematous base
● Exudative plaque covered with honey-colored crusts
● Removal of the crust reveals an erosion
● On drying, the crust falls leaving erythema which fades
without scarring.
Common Sites: Face (periorificial area)

8. Differential diagnosis
❖ Bullous Impetigo
❖ HSV infection
Treatment
❖ Localized lesions: Topical antibiotics like fusidic acid or mupirocin
❖ Extensive lesions: Systemic antibiotics (erythromycin group) If
resistance present then amoxicillin–clavulanic acid or cephalexin

9. Bullous Impetigo
Causative Bacteria: S. aureus
Age: Newborn and infants

10. Morphology
● Bullae, containing turbid fluid
● Erythematous halo (+/-)
● Rupture after a few days and forms thin, varnish-like crusts
● Heal in the center to form annular plaques.
● Sites: Face (sites of existing skin disease)

12. Differential Diagnosis
❏ Impetigo Contagiosa
Complications
❏ Staphylococcal scalded skin
syndrome
❏ Lymphadenopathy (Rare)
Treatment
❏ Local hygiene
❏ Localized lesions: Topical
antibiotics (Mupirocin)
❏ Extensive lesions: Systemic
antibiotics (amoxicillin
clavulanic acid, methicillin)

14. SSSS
❖ Staphylococcal Scalded Skin
Syndrome
❖ S. aureus infection present at
distant sites, like middle ear,
lungs, skin which produces an
exotoxin (exfoliative toxin)
which spreads hematogenously
and causes a split in the upper
layers of epidermis

15. Clinical Features
Infants.
Onset is acute with fever and skin tenderness.
Initial erythema and tenderness followed by superficial peeling of the skin in
thin sheets to reveal moist erythematous floor
Mucous membranes spared
However, Lesions DO NOT contain any
microorganism

16. Treatment
❏ Supportive and nursing
measures
❏ initially intravenous later oral
antistaphylococcal antibiotics

17. Ecthyema
A consequence of neglected impetigo contagiosa.
Deep Pyoderma
Causative Organism:
● S. pyogenes.
● S. aureus

18. Predisposing factors:
★ Poor hygiene
★ Malnutrition
★ Minor injuries
★ Insect bites
★ Scabies

20. Morphology
❏ Small bulla or pustule on an erythematous base
❏ Forming a crusted, indurated, tender plaque, with an
erythematous, edematous areola
❏ Removal of crust reveals an irregular punched out ulcer
❏ Site: legs, thighs, and buttocks

21. Treatment
● Local hygiene.
● Treat predisposing factors.
● Systemic antibiotics (penicillin/ erythromycin group).

22. Superficial Folliculitis
❏ Infectious: S. aureus
❏ Can also be Chemical.
Eg. Mineral Oils, Petroleum,
Cosmetic exposure
Or
❏ Mechanical
Eg. Post Shave/Wax.

23. Morphology
● Dome-shaped follicular pustules
○ Site: Legs > Forearms
● Mechanical aka Pseudo-folliculitis
○ beard area (after shaving)
○ thighs or and arms (after hair removal eg. waxing)

24. Treatment
● Infectious
○ Localized: Topical Antibiotics
○ Extensive: Systemic Antibiotics
● Chemical/ Mechanical
○ Removal of trigger
○ Correction of shaving/waxing technique
○ Topical steroid-antibiotic combination
○ Retinol

25. Deep Folliculitis
● Etiology: S. aureus
● Deep seated, erythematous follicular papules and pustules
● Sites: Beard
○ Scalp
● Treatment
○ Systemic Antibiotics

28. Furuncle
● A painful, pus-filled bump under the skin
caused by infected, inflamed hair follicles.
● Deep-seated follicular and perifollicular
infection
● Etiology: S. aureus
● Adolescent boys most susceptible

29. Predisposing Factors
❏ Nasal/perineal carriage of S.
aureus.
❏ Diabetes, HIV infection.
❏ Underlying skin disease, e.g.,
scabies, atopic dermatitis

30. Clinical Features
● Pain at site
● Usually one to two tender, firm red, follicular nodules which become
necrotic and discharge their central core.
● Lesions heal with barely perceptible scarring
● Sites: Hair-bearing, friction prone sites eg. face axillae, buttocks, legs
and perineal region

31. Treatment
Acute Episode
Hot Compress
Antibiotics
Surgical incision and
drainage of pus
Chronic/ recurrent episodes
Antibiotics
Treat carrier state with topical
mupirocin applied intranasally
and in perineum
Rifampicin

32. Carbuncle
Deep infection of contiguous hair
follicles
Etiology: S. aureus
Deep infection of contiguous hair
follicles seen most frequently in
diabetics and in patients on
steroid therapy
Males > Females

33. Clinical Features
❏ Fever always present
❏ Lesions excruciatingly painful
❏ Tender, lobulated, indurated, intensely erythematous plaque
discharging pus from many openings
❏ Heals with scarring
Sites: Back >>> Neck > Thighs

34. Treatment
Hot Compress
Aggressive treatment with flucloxacillin or other penicillinase-resistant
antibiotics
Incision and drainage

35. Carbuncle V/S Furuncle
A carbuncle is a cluster of Furuncles (boils) that form a connected area of infection under the skin

36. Erysipelas Cellulitis
Erysipelas is a superficial spreading
pyoderma
Cellulitis is deeper spreading pyoderma

37. Clinical Features
Acute erythematous, warm,
indurated, rapidly spreading
plaques
Margin is sharply defined
and superficial vesiculation
may occur on the plaque
Acute erythematous, warm,
indurated, rapidly spreading
plaques
Lesion is ill-defined and deeper
Skip areas characteristic

38. Sites: Lower > Upper Limb > Face
Fatal
If untreated

39. Treatment
● Symptomatic treatment
○ Rest.
○ Limb elevation.
○ Nonsteroidal anti-inflammatory drugs
● Specific Treatment
○ Parenteral Penicillin
○ Erythromycin
● Recurrence managed with Benzathine Penicillin

40. Thank You