Bacterial infections
Bacterial Skin Infections
Pyodermas
 Soft tissue infections
 Superficial
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Pyodermas
Pus forming condition of skin
Causative organism:
 Staphylococcus aureus
 Group A ß haemolytic streptococci (GAS)
 Primary
Primary pyoderma is often idiopathic in nature
(occurring without any predisposing cause), and
may be a result of suppressed or compromised
immune status.
 Secondary
Secondary occurs in pre-existing skin conditions
such as eczemas, viral infections, scabies, etc.
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Impetigo
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Superficial epidermal infection
Commonly seen in children
Staphylococcus aureus, GAS
Warmth, humidity, poor hygiene, Atopic
dermatitis, diabetes mellitus
Variable pruritus, fever uncommonly
Clinical types: Impetigo Contagiosa, Bullous
Impetigo
Impetigo Contagiosa
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Non Bullous impetigo
Small vesicles quickly become pustules
Erosions with yellow brown crust
Scattered, discrete, may become confluent
Sites : face, arms, legs
Bullous Impetigo
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Bullous Impetigo
Vesicles / Bullae having turbid fluid
Hypopyon sign
No surrounding erythema
Moist erosions
Distribution
Face, legs, arms
Differential Diagnosis
a) Erosion:dermatitis, scabies
b) Bulla: Herpes zoster, bullous pemphigoid
dermatitis herpetiformis, burns
Ecthyma
Develops in neglected lesions e.g. trauma in
diabetes mellitus
 Pain, tenderness
 Deep, crusted lesions - ulcerates
 Tenderness, induration
 Sites: legs & buttocks
 Lymphadenopathy
 Heals with scars
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Impetigo and Ecthyma
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Diagnosis
Mostly clinical; Gram’s stain, culture
Treatment
General – antiseptic baths
Topical: Antibacterials such as mupirocin
Oral:
GAS – erythromycin, cephalexin
S. aureus – cephalexin, amoxycillin – clavulinic
acid
MRSA - ciprofloxacin, trimethoprim sulphamethoxazole
Infectious folliculitis
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Infection of upper portion of hair follicle
Mostly Staphylococcus aureus
Predisposing factors: Shaving hairy areas,
extraction of hair, occlusion, high temperature,
humidity, diabetes mellitus
Progresses within days and extends upto months
Pruritic, mild pain
Lymphadenopathy rarely seen
Grouped papules/pustules confined to ostium of
hair follicle
Minimal scarring, post inflammatory pigmentation
seen
Infectious folliculitis
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Face - coexist with acne
Beard - Sycosis barbae
Neck - Keloidal folliculitis
Legs - involvement common in India
Trunk - Hot tub folliculitis, Pityrosporum folliculitis
Folliculitis - face
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Superficial folliculitis with thin walled pustules at
follicular orifice
Can present on scalp and face, especially seen
at perioral areas
May arise at sites of trauma
Develops in crops and heals within few days
Most frequent cause Staphylococcus aureus
Sycosis barbae
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Chronic, follicular, perifollicular, pustular,
staphylococcal infection of the beard area
Develops as erythema, itching near upper lip or
nose
Pin head sized pustules may develop, pierced
by hair
Differential diagnosis: Dermatophytic infection,
acne vulgaris, herpetic sycosis
Keloidal folliculitis
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Keloid like papules and plaques on the occipital
scalp and the back of the neck
Starts as chronic folliculitis and perifolliculitis
Heals with keloidal scars, sometimes with
discharging sinuses
Painful and cosmetically disfiguring
Treatment : with topical antibacterials,
Intralesional Steroids,
Prevention of trauma
Chronic folliculitis
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DCPA (Dermatitis cruris pustulosa et
atrophicians)
Chronic folliculitis seen especially in young
Indian males
Involves anterior aspect of lower legs bilaterally;
may extend upto the thigh
Recalcitrant, lasting for several years
Usually clears after development of atrophy
Differential diagnosis of folliculitis
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Fungal
Pityrosporum folliculitis
Tinea capitis
Tinea barbae
Viral
Herpes simplex
Molluscum contagiosum
Syphilitic
Secondary syphillis
Infestation
Demodicidosis
Acneiform eruptions
Management: Folliculitis
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Diagnosis
- Gram’s stain
-KOH mount
- Culture
Management
- Prevention
- Antibiotics
Topical – Mupirocin, Clindamycin
Oral as per culture and sensitivity studies
Abscess, Furuncle and Carbuncle
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Staphylococcus aureus
Predisposing factors
- Chronic carrier states
- Diabetes Mellitus
- Obesity
- Poor hygiene
- Bactericidal defects (e.g. chronic
granulomatous disease)
- Hyper - IgE syndrome
Abscess, Furuncle and Carbuncle
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Abscess is circumscribed collection of pus
Furuncle is an acute deep necrotising infection
of a hair follicle and perifollicular area
Carbuncle is a deep infection involving multiple
contiguous hair follicles
Clinical Presentation
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Abscess
Erythematous, warm, painful/tender
Arises in the dermis, subcutaneous fat or
muscle
Tender nodule; central pus collection
Furuncle
Arise in hair bearing area
Firm tender nodule
Central necrotic plug
Usually follow staphylococcal folliculitis
Abscess formation below necrotic plug
Clinical Presentation
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Carbuncle
Evolution similar to furuncle
Deep infection of a group of contiguous follicles
with Staphylococcus aureus
Sieve like openings draining pus
Management
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Grams’ stain and culture
Treatment
Incision and drainage
Systemic antibiotics
Recurrent furunculosis
Due to persistent S. aureus
Proper cleansing measures
Nasal, inguinal, axillary and perianal mupirocin
Rifampicin 600 mg PO for 7 - 10 days for MRSA
Erysipelas and Cellulitis
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Soft tissue infections – Acute, diffuse,
edematous inflammation of dermis and
subcutaneous tissue.
Erysipelas – Superficial soft tissue infection of
dermis & upper subcutaneous tissue. Raised
plaque with sharp margins.
Cellulitis – Inflammation of subcutaneous tissue.
Not raised and no clear margins.
Erysipelas and Cellulitis
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GAS (erysipelas) or S. Aureus
Arises via a portal of entry in skin or mucous
membrane
Fever with chills, malaise, local pain and
tenderness
May become necrotising
Clinical Presentation
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Red, hot, edematous shiny plaque
Well demarcated border in erysipelas
Vesicles, bullae, erosions, abscesses and
necrosis
Breaks in skin, chronic dermatitis
Risk factors
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Diabetes
Immunodeficiency
Drug and alcohol abuse
Cancer and chemotherapy
Chronic lymphedema
Cirrhosis
Neutropenia
Renal failure
Systemic atherosclerosis
Management
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Diagnosis
Gram’s stain and culture
Rule out systemic involvement by blood tests
and imaging
Prognosis
Favorable if treatment started early
Hematological and lymphatic dissemination if
treatment delayed
Treatment
Supportive: rest, leg elevation, analgesia
Appropriate antibiotics
Superficial Cutaneous Infections
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Affect stratum corneum
Overgrowth of normal flora
Three infections
Erythrasma
Pitted keratolysis
Trichomycosis axillaris
Erythrasma
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Corynebacterium minutissimum
Humid climate and occlusion
Asymptomatic; occasional pruritus
Sharply marginated reddish brown patch/macules
Groin fold, axillae, intergluteal & submammary
folds
Wood’s lamp: coral red fluorescence
Treatment: Erythromycin, oral and topical if
extensive lesions. Topically azole antifungal
agents-clotrimazole & miconazole for 2 weeks
Pitted Keratolysis
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Micrococcus sedentarius
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Hyperhidrosis of feet; occlusive footwear
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Asymptomatic, foot odour, itching
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Discrete / confluent pits in toe webs or on heels
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Treatment: Reduce moisture, absorbing
powders, erythromycin oral/topical, benzoyl
peroxide
Trichomycosis Axillaris
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Aerobic Corynebacteria
Adherent brown black, yellow, red concretions
on hair shaft which can be hard, soft,
nodular/more diffuse
Axillae and pubic areas
Underlying skin normal
Treatment: Shaving/ clipping/ topical
antimicrobials
Other Bacterial Infections
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Paronychia
Periporitis
Staphylococcal scalded skin syndrome
Toxic shock syndrome
Scarlet fever
Paronychia
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Acute infection of the nail fold
Facilitated by cuticular damage.
Clinically manifested as painful swelling of the
proximal/ lateral nail fold
Bacterial Culture and sensitivity helps in
diagnosis
Differential diagnosis: Herpetic whitlow, fungal
paronychia
Treatment involves incision and drainage;
systemic and topical antibiotics
Periporitis
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Pustular lesion, mostly in children during
summers, due to staphylococcal infection of
sweat gland
Sites: face, buttocks, upper trunk, scalp
May progress to sweat gland abscess
Clinically present as erythematous deep seated
nodules. May localize and rupture, leaving
behind scar
Differential diagnosis: Furuncles, Miliaria
pustulosa
Treatment : topical &/or oral antibiotics.
Prevention: minimizing sweat retention in the
affected area
Staphylococcal Scalded Skin Syndrome
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Generalized, confluent, superficially exfoliative
disease
Mostly occurs in neonates and young children.
Due to action of exfoliative exotoxins type A and
B liberated by staphylococcus aureus.
Fever, skin tenderness and erythema involving
the neck, groins and axillae followed by
generalized desquamation.
Diagnosis by histopathology,
immunofluorescence and frozen section of
peeled skin.
Treatment: Immediate institution of appropriate
antibiotic therapy such as methicillin,
erythromycin.
Toxic Shock Syndrome
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Acute febrile multisystem disease
Mediated by one or more toxins elaborated by
staphylococcus aureus
Occurs due to infections in wounds, catheters,
nasal packs
Diagnosis: primarily clinical, supported by the
confirmation of staphylococcal infection
Treatment: systemic antibiotics;
Intensive supportive treatment
Scarlet Fever
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Streptococcal pharyngitis, tonsilliits or cellulitis
causing diffuse erythematous exanthem
because of pyrogenic exotoxin.
Manifested as red tonsils, strawberry tongue,
diffuse erythema, Pastia’s lines, circumoral
pallor with facial flushing.
ASO titre may be diagnostic
Treatment: systemic antibiotics
Secondary Pyodermas
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Secondary bacterial infections in pre-existing
dermatological conditions
May complicate conditions such as scabies,
pediculosis, atopic dermatitis and
neurodermatitis
Treatment: appropriate oral and/or topical
antibiotics; treat pre-existing disease
Management of Pyodermas:
General Principles
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Identify, Assess and Treat Predisposing factors:
Poor hygiene, Malnutrition, Recurrent trauma,
Diabetes mellitus, Pre existing skin diseases ,
Congenital and acquired Immunodeficiency
Investigations:(recalcitrant and recurrent
infections)
For the identification of predisposing factors
Smear, Culture and Antibiotic Sensitivity test
(SCABS).
Management of Pyodermas:
General Principles
Topical Therapy:
 Soaks /compresses: Condy’s solution (KMNO4),
Burrow’s solution (aluminum chlorohydrate)
 Topical Antiseptics: Chlorhexidine, Povidine
iodine.
 Topical antibiotics : Mupirocin, Framycetin,
Sisomicin, Nadifloxacin, Neomycin, Gentamicin
Polymyxin B, Bacitracin, Fusidic acid.
Systemic therapy :
 Semi synthetic penicillins, Cephalosporins,
Macrolides, Tetracyclines, Quinolones.
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