Clinical Guides
Impetigo
A clinically focused, India-facing guide to recognising impetigo, using proportionate antimicrobial therapy, limiting spread and escalating invasive or atypical skin disease safely.
MedNext Academy | 12 min read
Impetigo
A clinically focused, India-facing guide to recognising impetigo, using proportionate antimicrobial therapy, limiting spread and escalating invasive or atypical skin disease safely.
Summary
Impetigo is a contagious superficial bacterial skin infection. Non-bullous impetigo is commonly caused by Staphylococcus aureus, Streptococcus pyogenes or both; bullous impetigo is caused by toxin-producing S. aureus. Non-bullous lesions usually begin as papules or pustules that break down into adherent golden or honey-coloured crusts, often on exposed face or limbs. Bullous disease has flaccid bullae and may be more widespread. The diagnosis is commonly clinical, but a lesion swab becomes important when treatment fails, disease recurs, resistance is suspected, or an outbreak is being investigated.
The therapeutic choice is not simply 'antibiotic versus no antibiotic'. Few localised non-bullous lesions may be suitable for a topical antimicrobial or, in selected cases, a no-antibiotic approach with clear review; widespread, bullous, systemically unwell, rapidly progressive or high-risk disease needs oral therapy or urgent reassessment. Treating every crust with oral antibiotics creates avoidable adverse effects and resistance, while undertreating spreading infection can permit cellulitis, dehydration in infants, staphylococcal scalded-skin syndrome or delayed post-streptococcal glomerulonephritis.
Hygiene, lesion covering, handwashing and avoiding shared towels, clothing and bedding reduce household and school transmission. Do not prescribe prophylactic antibiotics to ordinary contacts. Product choice, duration and return-to-school rules vary with local policy and resistance. This guide is educational, not an Indian formulary or a substitute for paediatric, dermatology or infectious-disease review.
How Common Is It?
Impetigo is common in young children, especially between two and five years, but can occur at any age. It is favoured by close contact, breaks in the skin, scabies, eczema, insect bites, warm humid conditions and crowding. It is more frequent in tropical and subtropical settings, which is relevant to parts of India, but a climate association is not a diagnosis and does not identify the organism or resistance pattern in an individual lesion.
No single current Indian national estimate reliably describes impetigo prevalence, aetiology or antimicrobial susceptibility in every setting. Community surveys, school inspections, dermatology clinics and hospital microbiology data sample different populations. Many mild cases are treated without a culture or with over-the-counter medicines, and a positive swab can reflect colonisation as well as the cause of an active lesion. Claims that a particular percentage is caused by streptococci or MRSA should therefore be tied to place, specimen method and date.
The meaningful burden includes missed schooling, caregiver time, inappropriate antibiotic exposure, recurrent disease from untreated scabies or household transmission, and rare invasive complications. A cluster in a school, hostel, sports team, neonatal unit or crowded household calls for infection-control assessment rather than repeated individual prescriptions. Surveillance should distinguish impetigo from cellulitis, abscess and fungal disease, record lesion extent and cultures where taken, and avoid using pharmacy sales as an incidence denominator. The patient in front of the clinician needs a severity and differential assessment, not a prevalence statistic.
Risk Factors
A disrupted skin barrier is the central risk. Atopic eczema, scabies, pediculosis, insect bites, abrasions, burns, varicella and scratching provide entry points. Ask about recurrent itch, household itch, nocturnal symptoms and close contacts because treating a bacterial crust without identifying scabies can lead to rapid recurrence. Nasal or skin carriage may matter in recurrent staphylococcal disease, but decolonisation is not a routine response to a first uncomplicated episode.
Close contact with someone who has draining lesions, sharing towels or sports equipment, crowded childcare and poor access to water or laundering increase transmission risk. Poor hygiene should be discussed without blame: a family may have limited water, private washing space, time, or ability to keep a child away from school. Malnutrition, diabetes, immune suppression, nephrotic syndrome, pregnancy-related skin changes and chronic oedema can alter healing or raise the threshold for review.
Antibiotic exposure and self-treatment can obscure presentation. Topical steroid combinations may worsen or mask infection; unregulated creams may contain potent steroids, antifungals or antibiotics. Prior macrolide or clindamycin use can matter where resistance is present. Do not infer methicillin-resistant S. aureus from severity alone. Obtain a culture when disease is recurrent, extensive, non-responsive or unusual, and use the result with local susceptibility data. A child with fever, pain out of proportion, rapidly spreading erythema or toxic appearance has a different risk profile from uncomplicated impetigo and needs urgent assessment for deeper infection.
Diagnosis
History
Ask about onset, itch, pain, fever, rapid spread, bullae, discharge, trauma, insect bites, eczema, scabies, prior episodes, household contacts, school or sports exposure and current creams or antibiotics. Establish drug allergy carefully, including immediate reactions versus non-allergic gastrointestinal symptoms. Ask about diabetes, immune suppression, renal disease, pregnancy and neonatal age. In recurrent disease, ask whether prior treatment was applied as prescribed, whether all contacts with scabies were treated, and whether towels or bedding were shared.
Examination
Examine lesion morphology, distribution, surrounding erythema, warmth, tenderness, bullae, erosions, crust and lymph nodes. Non-bullous impetigo has superficial pustules and honey-coloured crust; bullous impetigo has fragile superficial bullae. Look for ecthyma, cellulitis, abscess, scabies burrows, eczema, tinea, herpes lesions, varicella, insect bites and trauma. Assess temperature, hydration and overall appearance in children. Pain out of proportion, rapid progression, purpura, crepitus, mucosal involvement, widespread peeling or systemic illness needs emergency escalation.
Investigations
Diagnosis is usually clinical. CDC notes that culture of exudate or pus can identify the bacterial cause but is not routinely required for a typical first episode. Swab an open, untreated lesion if empiric therapy fails, disease recurs, MRSA or unusual infection is suspected, a neonatal or institutional cluster occurs, or oral treatment decisions depend on susceptibility. Culture after topical antibiotics may be falsely negative. Do not swab intact skin as though it proves active infection. Screen glucose or immune status only when history or poor healing indicates it; unnecessary panels distract from examining the skin and reviewing treatment.
Differential Diagnosis
Ecthyma is a deeper ulcerative form of pyoderma that extends into dermis and usually needs oral therapy; it should not be managed as a few superficial crusts. Cellulitis causes diffuse painful erythema and warmth without the classic superficial honey crust, and abscess needs examination for drainage. Staphylococcal scalded-skin syndrome, particularly in infants and young children, causes tenderness, widespread erythema and superficial desquamation and requires urgent hospital care. Necrotising infection is rare but pain out of proportion, toxicity, rapid spread, bullae or crepitus are red flags.
Herpes simplex can cause grouped painful vesicles, eczema herpeticum causes monomorphic punched-out erosions with systemic illness, and varicella has lesions at different stages. Tinea, candidiasis, seborrhoeic dermatitis, contact dermatitis, insect bites and atopic eczema may crust after scratching but require different treatment. Perioral dermatitis and impetiginised eczema can be confused with primary impetigo. Consider abuse or trauma only from a careful contextual assessment; do not label a skin lesion without evidence.
Post-streptococcal glomerulonephritis is a delayed complication, not a feature of active impetigo. Dark urine, oedema, reduced urine or hypertension one to two weeks after streptococcal skin infection needs assessment. Acute rheumatic fever after skin infection is an evolving evidence area and should not be promised as prevented by a particular topical regimen. If cultures identify unusual organisms, lesions are recurrent or there is poor response, reassess the diagnosis and adherence rather than escalating antibiotic spectrum reflexively.
Management
Give practical infection-control advice at the first visit: wash hands after touching lesions, keep nails short, cover lesions where feasible, avoid sharing towels, clothing, razors or sports equipment, and wash used linen and clothes. CDC advises that antibiotic treatment and lesion covering limit transmission; school or work return is governed by local policy and clinical appearance. Treat associated scabies, eczema or other skin-barrier disease, otherwise antibacterial treatment alone may fail.
Current guidelines recommends no antibiotic or hydrogen peroxide 1% cream for some localised non-bullous impetigo, depending on suitability and preference; a short topical antibiotic is an alternative when needed. Do not routinely combine topical and oral antibiotics. Offer an oral antibiotic for bullous impetigo, people systemically unwell or at high risk of complications, and consider it for widespread non-bullous disease when topical therapy is impractical. Antibiotic choice must cover likely staphylococcal and streptococcal pathogens and follow current local susceptibility guidance.
Review within the planned interval or earlier for spreading lesions, fever, pain, worsening redness, no response or adverse effects. Swab before changing treatment in recurrent or non-responsive disease when practical. Avoid automatic antiseptic overuse, prolonged topical antibiotics and repeated empiric broad-spectrum courses. Referral may be required for newborns, immune-suppressed people, significant eczema, suspected scalded-skin syndrome, cellulitis, deep infection or outbreak control. Explain that antibiotics do not replace hygiene and that contacts without lesions generally do not need preventive antibiotics.
Prescribing Information
Topical antibiotics are not harmless. Mupirocin, fusidic acid, retapamulin and other products have different local licences, availability and resistance implications. Use the narrowest effective product for the shortest locally recommended course, with application limited to affected skin. Repeated or widespread topical antibiotic use can select resistance and cause contact dermatitis. current guidelines specifically advises against routine topical-plus-oral combinations for impetigo. Do not use steroid-antibiotic combinations to suppress an undiagnosed rash without assessing infection and eczema separately.
Oral therapy is chosen for bullous, widespread, high-risk or systemically unwell disease. Confirm allergy history, weight in children, renal or hepatic impairment, pregnancy, breastfeeding, drug interactions and local resistance. Penicillin has not had a reported clinical GAS resistance isolate in CDC guidance, but non-bullous impetigo may also involve S. aureus and macrolide or clindamycin resistance varies geographically. A reported penicillin allergy does not automatically make a macrolide appropriate; immediate hypersensitivity, culture results and local advice matter.
Prescribe exact dose and duration from the current Indian product information or institutional antimicrobial policy, not this guide. Record indication, lesion extent, review date and adverse-effect advice. Consider culture before second-line treatment, particularly after recent antibiotics. In neonates, pregnancy, severe renal disease, immune suppression or suspected invasive infection, discuss with paediatrics, obstetrics, dermatology or microbiology. Antimicrobial stewardship means both avoiding unnecessary treatment and ensuring that genuinely extensive infection receives adequate, monitored therapy.
When to Refer
Refer urgently to hospital for a neonate with suspected impetigo, a child or adult who is systemically unwell, widespread bullous disease, rapidly spreading cellulitis, severe pain, dehydration, immune suppression, facial or periorbital involvement with eye symptoms, or concern for staphylococcal scalded-skin syndrome or necrotising infection. Acute red eye, visual change or inability to open the eye needs ophthalmic assessment, not merely topical skin treatment.
Seek dermatology, paediatric, infectious-disease or microbiology advice for recurrent episodes, failure after appropriate therapy, suspected MRSA, significant eczema, extensive scarring or pigment change, unusual distribution, institutional clusters or a need for decolonisation strategy. A patient with dark urine, oedema, hypertension or reduced urine after skin infection needs medical assessment for possible post-streptococcal glomerulonephritis. Household scabies or repeated shared exposure may need coordinated community treatment rather than referral of one child alone.
In India, local access to culture, susceptibility testing, dermatology and paediatric care differs. Referral should identify a reachable facility and provide the lesion history, photographs if consented, prior topical and oral products, allergy history, systemic signs and social exposure context. Do not promise a particular antibiotic, MRSA test or school exclusion duration. Public-health advice in outbreaks must follow local authority direction, especially in schools, hostels, neonatal units and food-handling settings.
Red Flags
Immediate review is needed for fever, lethargy, poor feeding, vomiting, dehydration, rapidly spreading erythema, severe tenderness, pain out of proportion, purpura, haemorrhagic bullae, skin necrosis, crepitus, hypotension or altered mental state. These features point beyond uncomplicated superficial impetigo to cellulitis, sepsis, scalded-skin syndrome, toxic shock or necrotising soft-tissue infection. Infants, especially neonates, can deteriorate quickly and should be assessed with a low threshold.
Periorbital swelling, eye pain, visual symptoms, proptosis or impaired eye movement may signal preseptal or orbital cellulitis. Widespread erythema and tenderness with superficial peeling, mucosal sparing and a positive Nikolsky sign suggest staphylococcal scalded-skin syndrome and need hospital treatment. Eczema herpeticum is another emergency when a child with eczema has painful monomorphic erosions, fever or eye involvement.
Delayed renal symptoms after a preceding skin infection—tea-coloured urine, oedema, hypertension or reduced urine—need urgent assessment. Treatment red flags include rash, facial swelling, wheeze, severe diarrhoea, jaundice or neurological symptoms after antibiotics. Parents and carers should receive a written plan for spreading redness, fever, poor feeding and reduced urine, with a clear emergency route. Avoid telling families simply to wait for crusts to heal if the child becomes unwell or lesions are rapidly changing.
Indian Clinical Context
international and CDC guidance support stewardship but do not establish Indian first-line products, topical availability, resistance patterns or school policy. Local microbiology, state antimicrobial guidance, CDSCO labelling and institutional formulary must determine the antibiotic selected. Community access to clean water, laundry, follow-up and culture may be limited, so counselling should focus on feasible steps: hand hygiene, separate towels where possible, covering lesions and early review for deterioration.
Impetigo may coexist with scabies, eczema, fungal disease or insect bites. In crowded households, schools and hostels, treating one visible child while ignoring shared scabies exposure or access to washing can lead to recurrence and stigma. Avoid blame around hygiene, poverty or parenting. Ask about traditional creams and over-the-counter steroid-antibiotic combinations respectfully; the patient may not know their ingredients.
India-specific evidence on topical and oral resistance is geographically variable and changes over time. Do not state that an imported resistance rate applies locally. Culture is particularly valuable after failure, recurrent disease or a cluster, but lack of culture must not delay emergency transfer for systemic infection. NMC training supports skin examination, antimicrobial stewardship, infection prevention and referral, while exact competency coding must be checked locally. This guide is an awaiting-review educational draft and does not claim completed Indian clinical endorsement.
NMC Competency Mapping
Impetigo connects dermatology, paediatrics, microbiology, pharmacology and community medicine. Learners should recognise classic superficial lesions, differentiate bullous impetigo from ecthyma and cellulitis, examine for scabies and eczema, assess systemic illness, and take a medication and allergy history. They should know when culture has value and why a colonisation result or a swab from intact skin does not automatically define the infection.
At Know and Know How level, students explain the roles of S. aureus and GAS, transmission through lesion contact, hygiene measures, complications and principles of topical versus oral treatment. At Show How level, they demonstrate hand-hygiene counselling, lesion covering, medicine application instruction, return precautions and a safe referral for periorbital, neonatal or systemic disease. Antibiotic selection and paediatric dosing are supervised activities tied to the local policy and susceptibility data.
A practical assessment can present a child with honey-coloured facial crusts and household itch, asking for morphology, scabies assessment, first treatment category and household advice. A second vignette with fever, painful spreading erythema or a neonate tests emergency escalation. Professionalism includes non-stigmatising discussion of hygiene, avoiding unnecessary antibiotics and protecting a child's school participation while reducing transmission. Consult current NMC regulations and the adopted institutional curriculum for formal code-level mapping.
Key Exam Pearls for NEET PG
Non-bullous impetigo is a superficial infection caused by S. aureus, GAS or both; papules and pustules form thick honey-coloured crusts. Bullous impetigo is caused by toxin-producing S. aureus. Impetigo is usually clinical; culture is reserved for atypical, recurrent, non-responsive or outbreak-related disease. Ecthyma is deeper and ulcerative. Scabies and eczema are common predisposing conditions and need parallel management.
Use topical treatment only for limited disease when appropriate; oral treatment is considered for widespread or bullous disease, systemic illness or high risk. Do not routinely combine topical and oral antibiotics. Repeated topical antibiotics promote resistance. Penicillin resistance has not been reported in GAS clinical isolates, but impetigo can include S. aureus and macrolide or clindamycin resistance varies by place and time. Choose treatment from the current local policy.
Complications and red flags matter: post-streptococcal glomerulonephritis can occur one to two weeks later; dark urine, oedema and hypertension require review. Fever, pain out of proportion, rapidly spreading cellulitis, bullae with systemic illness, neonatal disease, periorbital symptoms or widespread peeling require urgent assessment. Handwashing, covering lesions and not sharing linen reduce transmission; routine prophylactic antibiotics for contacts are not indicated.
Frequently Asked Questions
Does every child with a few honey-coloured crusts need oral antibiotics?
No. The choice depends on lesion number, bullae, spread, systemic illness, risk of complications, ability to apply topical treatment and local guidance. current guidelines permits no-antibiotic or topical approaches in some localised non-bullous cases, while oral treatment is used for bullous, widespread or high-risk disease. A clinician should review worsening, failure to improve or diagnostic uncertainty rather than automatically escalating antibiotics.
Can a swab identify whether impetigo is staphylococcal or streptococcal?
Culture of exudate or pus can identify bacteria, but a typical first episode is commonly diagnosed clinically and does not always need a swab. Swabs are more useful after treatment failure, recurrence, unusual disease, suspected resistant infection or a cluster. The sample should be from an active lesion and interpreted with the clinical picture because skin colonisation can occur.
Should family members take antibiotics to prevent impetigo?
Usually no. Routine preventive antibiotics for ordinary close contacts are not recommended. Instead, cover lesions, wash hands, avoid sharing towels, clothing and bedding, and assess household scabies or active lesions. Public-health or infectious-disease advice is appropriate for outbreaks, high-risk settings or repeated transmission, where a coordinated strategy may be needed.
When can a child return to school after impetigo?
Follow the local school and public-health policy. CDC notes that children with group A strep infection can generally return when well appearing and at least 12 hours after appropriate antibiotic treatment, with lesions covered, but local rules may use a different time frame or require 24 hours. A child with fever, spreading disease or untreated active lesions needs reassessment rather than school clearance.
Inside MedNext for this topic
- 411 MedNext-authored chapters
- 80,000+ MCQ bank
- 15 study modes
- a growing library of visual revision sheets
Study modes
- Notes
- MCQ
- Audio
- Video
- Visual
- 3D Anatomy
- Trace
- Flashcards
- Mnemonics
- Image Bank
- Clinical
- Microscopy
- Audio QBank
- Cadaver
- Book Match
Continue reading
Clinical GuidesAll Clinical Guides
Browse all clinical management guides for Indian medical practice.
Test your knowledge
Attempt structured MCQs on this topic to consolidate your understanding and connect the guide to exam-focused practice.
Try MCQs on this topic