Introduction

Did you know that the term Impetigo was derived from the Latin word Impetere which means ‘attack’. This is because of the highly contagious nature of the disease.

Impetigo is a bacterial infection that affects the superficial layers of the skin.¹ It occurs predominantly in children but can also be seen in adults. Impetigo is primarily caused by the bacteria Staphylococcus aureus. Sometimes it may be due to Streptococcus pyogenes. It commonly affects the face, hands and feet, although it may occur in any part of the body. Though common in children, the adaptation of the immune system to accommodate the unborn baby places the pregnant woman at risk of impetigo. The disease is usually mild and localised but may be severe and disseminated in some cases. Antibiotics play a major role in the management. If untreated, there may be complications for the mother and baby.

Types of Impetigo

Impetigo can also be classified as primary Impetigo if it affects intact skin or secondary Impetigo if it affects previously injured skin.

Causes of skin injury that predispose to impetigo include scratching, insect bites, burns, trauma and viral skin lesions like varicella and herpes.² 

There are three main types of impetigo and a fourth rare type that may be present in pregnant women.

Non-bullous Impetigo

It is commonly caused by Staphylococcus aureus, but can also be caused by Streptococcus pyogenes in about 10% of cases.¹ It usually starts as multiple blisters or pustules(a small blister containing pus). These can rupture and merge to form larger lesions. It is associated with crust formation at the base but is not usually associated with fever

Bullous Impetigo

This is seen more in neonates(children less than one month), though it can also be present in older children (ages 2-5 years) and adults.² It is caused exclusively by S. aureus. It usually starts as small vesicles( a small fluid-filled cyst) that transform into a bullae (large blisters filled with clear fluid). The bullae usually rupture to reveal a reddish base. It is not associated with crust formation and the lesions are fewer than you have in non-bullous impetigo. It is more associated with fever and other systemic symptoms.

Ecthyma

It is a deeper form of impetigo that penetrates the deeper layer of the skin(dermis). It is a consequence of untreated Impetigo. It presents as punched-out ulcers (deep wounds with circular margins) that are associated with honey-coloured or brown-black crusts. It may be associated with the swelling of the lymph nodes around the area of the lesion.

Impetigo herpetiformis

It is a rare skin lesion that presents almost exclusively in the third trimester of pregnancy.^3,4,5 As of 2020, only 350 cases have been reported in European and American literature since year 2000. It is of unknown origin but there are speculations that it may related to reduced calcium levels and poor function of the parathyroid gland. It presents as sterile (free from microorganisms) pustules on the body fold with subsequent spread to the trunk. It may also become widespread and spread to distant areas like the tongue and the oesophagus. The relationship between it and bacteria infection is questionable. It is also called ‘pustular psoriasis of pregnancy’.

Risks of Impetigo during pregnancy

Any condition that causes a reduction in the body’s ability to fight infections increases the risk of having impetigo. 

Risk factors include;

•  Pregnancy
•  Malnutrition
•  Immunosuppression
•  Diabetes
•  Poor hygiene 
•  living in warm climates

There is a relative immunodeficiency in pregnancy. This is an adaptation to accommodate the unborn baby. This adaptation increases the risk of developing infections which can harm the mother, the baby or both.

Maternal risks

Maternal risks of Impetigo include;

• Higher risk of contracting impetigo, especially secondary infections from close contacts(people sharing the same household/workspace)
• Higher risk of dissemination of the infection to the kidneys, joints, lungs and bones 
• Higher of developing complications like cellulitis and abscess
• The rare form of non-bacterial impetigo(Impetigo herpetiformis) is also associated with delirium and seizures because of its association with reduced calcium levels⁵

Risk to the baby

The risks to the baby could be due to improper treatment or delay in treatment. Systemic infection in the mother can lead to placental insufficiency( reduced function of the placenta leading to reduced transfer of blood and nutrients to the baby)

The risks could also result from the medication used in the treatment.

The risks to the unborn baby include:

• Miscarriage
• Congenital anomalies
• Premature delivery 
• Growth restriction 
• Death of the unborn baby

Symptoms and diagnosis of Impetigo in pregnant women

Symptoms

Symptoms of impetigo depend on the type of impetigo. 

Common symptoms include;

• Multiple red blisters containing pus or clear fluid in non-bullous Impetigo
• Large bullae in bullous Impetigo
• Yellow or honey-coloured crusts(after the rupture of the blisters)
• Painful deep ulcers (wound) seen in ecthyma
• Discomfort and itching
• Swelling of the affected area
• Abscess formation

Systemic symptoms are usually present in bullous impetigo and impetigo herpetiformis. They include;

• Fever
• Diarrhoea
• Generalised weakness

Diagnosis

Diagnosis is usually based on symptoms and examination findings. The clinical findings(from the history and examination) are enough to make an accurate diagnosis. The characteristic sores and crusting are used to differentiate impetigo from other similar skin lesions.

Samples may be collected from the lesions for bacterial culture especially if there is suspicion of an antibiotic-resistant strain of S. aureus.

A biopsy(taking a part of the infected tissue for testing in the laboratory) may be required to confirm the diagnosis in some cases, particularly if the condition becomes refractory(resistant to treatment)

Treatment options for Impetigo during pregnancy

Antibiotic treatment

If untreated, Impetigo can resolve within a few weeks without treatment.

Even though impetigo can resolve on its own, antibiotics help to reduce

•  The duration of the disease 
•  The spread of the disease
•  Complications involving other organs like the kidneys and joints.

In pregnancy, consideration is given to fetal safety. Some antibiotics can cause abnormalities in the baby and these are generally avoided. Only medications whose potential benefits outweigh the risks are used.⁶ It is recommended that the full course of the antibiotic dose should be taken, even if the lesions dry up immediately after therapy is commenced.⁷

The treatment option depends on the type of impetigo. Local or systemic administration of antibiotics may be required. The antibiotics used should have activity against the causative organisms, S aureus and S pyogenes.

Topical (Local) treatment

Non-bullous impetigo usually requires local(topical) antibiotics. The preferred antibiotics include mupirocin, retapamulin, ozenoxacin and fusidic acid. These are creams that are applied directly to the lesion.

Mupirocin is a naturally occurring antibiotic produced by fermentation of the organism, Pseudomonas fluorescens. It acts by the inhibition of protein synthesis in bacteria. It is the recommended first-line treatment in pregnancy as it has been shown to limit the spread of the disease.

Systemic treatment

Systemic treatment is needed in patients with:

• Widespread lesions 
• Complicated infections
• Those associated with systemic manifestations

The antibiotics are usually administered either as oral or intravenous (through the vein) medications.

Systemic antibiotic therapy(relates to and affects the entire system) is required in Bullous impetigo. This is because of the presence of additional symptoms in other parts of the body. In addition, patients with non-bullous impetigo who have more than five lesions would require systemic therapy. Antibiotics with a wide range of activity like cephalosporins, dicloxacillin and amoxicillin-clavulanic acid are preferred. In pregnancy, the recommended first-line treatment for you is oral first-generation cephalosporins like cephalexin and oral dicloxacillin. This is because of their effectiveness and good safety profile. 

If you develop abscess or cellulitis and lack of response to conventional antibiotics, it may be suggestive of methicillin-resistant S.aureus infection (MRSA). This is a type of “S.auereus infection which does not respond to the antibiotics, methicillin. If this is confirmed by culture, your doctor would recommend clindamycin(an antibiotic) as the preferred therapy in pregnancy.²

Impetigo herpetiformis is treated with systemic steroids like prednisolone. Refractory cases may require the use of cyclosporine. Methotrexate and retinoids are not recommended in pregnancy as they cause harm to the unborn baby. They can be considered if the condition persists till the postnatal period. Some scholars are also in favour of additional treatment with antibiotics, even though cultures do not typically yield bacteria organisms.³ Since it is associated with reduced calcium levels, calcium and fluid replacement are essential in the management.

Non-antibiotic management

Non-antibiotic management is required to reduce discomfort, further aid healing and also to prevent the spread of the disease.

These include:

• Cleansing of the lesions with antibacterial soaps and removal of the crust
• Use of antihistamine medications to reduce itching
• Good hand hygiene with antibacterial washes
• Washing of clothes, bedding and contaminated surfaces
• Covering the wound with a bandage
• Avoiding close contact with uninfected persons (including the newborn baby)

These measures would facilitate healing and also limit the spread of the disease to other parts of the body. It would also limit the spread of the disease to close contacts.

Monitoring 

Mild infections do not usually harm the baby, severe infections, however, may affect blood flow to the baby, so there is a need for monitoring. Your doctor would monitor the baby by checking the heart rate and doing regular ultrasounds. This would help to determine the effect of the disease on the unborn baby. It would also enable timely intervention.

FAQs

What are the common sites for impetigo?

You're most likely to get an impetigo infection around your nose and mouth or your hands and feet, but impetigo sores can appear anywhere on your skin or the body. 

Is Impetigo airborne?

 Impetigo is not airborne, but it is contagious. You can get the infection if you touch infected skin or items that have touched infected skin (such as clothing, towels, and bed linens). 

Can I breastfeed my baby with impetigo?

Infected lesions on the breast and any other part of the body can spread to your baby when you breastfeed.

If you have impetigo, you should not breastfeed until the lesions have cleared. 

Summary

Impetigo is normally a mild condition, but it can become severe on occasion. Pregnancy raises the risk of infection for both mother and infant but early detection and therapy are necessary to shorten the duration of the disease. Rational antibiotic use is critical to ensuring positive outcomes for the mother and baby. Instituting preventive measures helps to curtail the spread of the disease.