impetigo

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By, M.Logeshwary (PharmD III year)

• IMPETIGO

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DEINITION

• Impetigo is a superficial skin infection that is
  seen most commonly in children and is transmitted
  easily from person to person.
• Based on clinical presentations

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• There are two ways an initial infection can
  occur
• primary impetigo - is when the bacteria invades
  the skin through a cut , insect bite, or other
  injury, and
• secondary impetigo - is where the bacteria
  invades the skin because the skin barrier has
  been disrupted by another skin infection, such as
  scabies or eczema.

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Epidemiology

• The bullous form most frequently affects neonates
  and accounts for approximately 10 of all cases
  of impetigo
• Based on data from studies published since 2000
  from low and low-middle income countries, we
  estimate the global population of children
  suffering from impetigo at any one time to be in
  excess of 162 million, predominantly in tropical,
  resource-poor contexts. Impetigo is an
  under-recognised disease and in conjunction with
  scabies, comprises a major childhood
  dermatological condition with potential lifelong
  consequences if untreated.

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Occurence

• On exposed skin mainly on face.
• most common during hot, humid weather, which
  facilitates microbial colonization of the skin.
• Minor trauma, such as scratches or insect bites,
  then allows entry of organisms into the
  superficial layers of skin, and infection ensues

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Causes

• Caused by S. pyogenes
• But S. aureus either alone or in combination with
  S. pyogenes has emerged more recently as the
  principal cause of impetigo
• The bullous form is caused by strains of S.
  aureus capable of producing exfoliative toxins

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BULLOUS IMPETIGO (BLISTERS)

• This form is caused by staph bacteria that
  produce a toxin that causes a break between the
  top layer (epidermis) and the lower levels of
  skin forming a blister. (The medical term for
  blister is bulla.) Blisters can appear in various
  skin areas, especially the buttocks, though these
  blisters are fragile and often break and leave
  red, raw skin with a ragged edge. No prior trauma
  is needed for these blisters to appear.

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NON -BULLOUS IMPETIGO

• This is the common form, caused by both staph
  and strep bacteria. It appears as small blisters
  or scabs, which then form yellow or honey-colored
  crusts. These often start around the nose and on
  the face, but they also may affect the arms
  and legs. At times , there may be swollen glands
  nearby.

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Pathophysiology

• Bullous impetigo is caused by staphylococci
  producing exfoliative toxin that contains serine
  proteases acting on desmoglein , a structurally
  critical peptide bond in a molecule that holds
  epidermal cells together. This process
  allows Staphylococcus aureus to spread under the
  stratum corneum in the space formed by the toxin,
  causing the epidermis to split just below the
  stratum granulosum. Large blisters then form in
  the epidermis with neutrophil .
• In bullous impetigo, the bullae rupture quickly,
  causing superficial erosion and a yellow crust,
• while in non-bullous impetigo, Streptococcus typic
  ally produces a thick-walled pustule with an
  erythematous base. Histology of non-bullous
  established lesions shows a thick surface crust
  composed of serum and neutrophils in various
  stages of breakdown with parakeratotic material

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Symptoms

• Pruritus(severe itching) is common, and
  scratching of the lesions may further spread
  infection through excoriation of the skin.
• Other systemic signs of infection are minimal.
• Weakness, fever, and diarrhea sometimes are seen
  with bullous impetigo.

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Signs

• Non bullous impetigo manifests initially as
  small, fluid filled vesicles.
• These lesions rapidly develop into pus-filled
  blisters that rupture readily.
• Purulent discharge from the lesions dries to form
  golden-yellow crusts that are characteristic of
  impetigo.
• In the bullous form of impetigo, the lesions
  begin as vesicles and turn into bullae
  containing clear yellow fluid.
• Bullae soon rupture, forming thin, light brown
  crusts.
• Regional lymph nodes may be enlarged.

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IS IMPETIGO CONTAGIOUS?

• Impetigo is contagious, mostly from direct
  contact with someone who has it.
• Can be transmitted through
• 1. towels,
• 2. toys,
• 3. clothing or
• 4. household items

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DIAGNOSIS

• Doctors generally diagnose impetigo by looking at
  the distinctive sores.
• Sometimes culture test are done rarely to
  identify the type of bacteria causing lesions.
• A complete blood count is often performed because
  leukocytosis is common.

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TREATMENT

• Impetigo is not serious, may go away and dry up
  on its own, and is easy to treat.
• Mild cases can be handled by gentle cleansing,
  removing crusts, and applying the
  prescription-strength antibiotic ointment
  mupirocin ( Bactroban).
• More severe or widespread cases, especially of
  bullous impetigo, may require oral antibiotic
  medication for impetigo.
• impetigo may resolve spontaneously, antimicrobial
  treatment is indicated to relieve symptoms,
  prevent formation of new lesions, and prevent
  complications, such as cellulitis.

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Treatment
DRUGS DOSAGE INDICATIONS
Penicillinase resistant penicillins (dicloxacillin) 12.5 mg/kg orally daily in four divided doses for children increased incidence of infections caused by S. aureus
First-generation cephalosporins Cephalexin 2550 mg/kg orally daily in two divided doses for children -
cefadroxil 30 mg/kg orally daily in two divided doses for children -
Penicillin administered as either a single intramuscular dose of benzathine penicillin G 300,000 600,000 units in children, 1.2 million units in adults infections caused by S. pyogenes
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TREATMENT

clindamycin adults 150300 mg orally every 6 to 8 hours children 1030 mg/kg per day in three to four divided doses The duration of therapy is 7 to 10 days. Penicillin-allergic patients can be treated
Topical antibiotics, such as mupirocin and bacitracin - used to treat non-bullous impetigo.
Mupirocin ointment applied three times daily for 7 days as effective as erythromycin.
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• With proper treatment, healing of skin lesions
  generally is rapid and occurs without residual
  scarring.
• Removal of crusts by soaking in soap and warm
  water also may be helpful in providing
  symptomatic relief

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EVALUATION OF THERAPEUTIC OUTCOMES

• Clinical response should be seen within 7 days of
  initiating antimicrobial therapy for impetigo.
• Treatment failures could be due to noncompliance
  or antimicrobial resistance.
• A follow-up culture of exudates should be
  collected for culture and sensitivity, with
  treatment modified accordingly.

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Case study

• OB, a 3-year-old boy, is brought to the clinic
  with a facial rash. According to OB's mother, the
  rash started 4 days ago as little red bumps below
  his nose. The rash has spread around his mouth
  and chin. The rash also has changed in appearance
  to flat, reddened areas with fluid-filled
  pustules. On physical examination, the
  pediatrician finds OB to be a content and alert
  child in no acute distress. His vital signs are
  stable and within normal limits. The pediatrician
  notes that some of the pustules have ruptured,
  leaving weepy, red lesions and honey-colored
  crusts. The affected area is not excessively warm
  or swollen.
• The pediatrician suspects that OB has impetigo.
  He explains to the mother that impetigo is a
  contagious condition that requires treatment with
  antibiotics. He knows that the most common
  pathogen causing impetigo is ( ?
  ), with ( ?
  )coinfection. The pediatrician is aware that
  impetigo was traditionally treated with
  penicillin, but resistance has limited the
  usefulness of this antibiotic. Instead he hopes
  to use an antibiotic that effectively will cover
  staphylococci and streptococci.
• As the pediatrician checks the supplies of
  medications available in the clinic, the mother
  comments that OB will not take any medications by
  mouth. She asks whether there are any medications
  that can be applied to the rash, rather than
  given by mouth.
• Are there any topical options available to treat
  OB's impetigo?
• Whether it is bullous or non-bullous impetigo?

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• Because many cases of impetigo involve
  coinfection with streptococci, antibiotic
  selection must consider covering for both
  organisms. Antimicrobial agents that will cover
  for both organisms include dicloxcillin,
  cephalexin, erythromycin, and amoxicillin/clavulan
  ate. Since OB will not take oral antibiotics,
  mupirocin ointment is another option. Mupirocin
  should be used only for mild cases, however.
• The pediatrician should advise the mother about
  the importance of not spreading the infection to
  the rest of the family (or even to other parts of
  OB's body). The most important measure of
  prevention is frequent hand washing. OB also
  should be reminded not to touch the rash.
• Non-bullous impetigo.

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Thank you smarties