With additional inputs from Dr.Vivek Verma (ID).
Thank you for asking your query at DoctorSpring.
Human body has a very good inbuilt immune system. That is the reason why your mother is not having any issues even when she is taking care of your grandmother without any precautions.
Your twins also have a good amount of own immunity and protection mechanism (initially from the mother, but later they develop own immunity), but not as strong as a grown up. The fact that they were premature and currently using steroid creams put them into some risk of contracting infections because of low immunity.
So yes, there is a slight risk of infection transmission directly from your grandmother or mother. But this risk not very high or does not require any extreme measures of isolation. The common bacteria which are causing the cellulitis are universal. They are found in many places and even in normal human skin. So an absolute isolation is pointless. Instead some smart and evidenced based precautions will make sense in this scenario.
1. Hand wash – This is the most important single factor that can help in prevent bacterial transmission. Normal intact skin of the baby will not transmit microorganisms. The risk occurs when there is contact with broken skin or wound, eye, nasal mucosa and genitalia. Washing hands prevents this kind transmission. Use a non-touch liquid soap. You can make it a rule (or habit) everyone should wash their hands thoroughly before handling them. You can make this rule universal and say it is needed because of the eczema (to avoid hurting any personal feelings)
2. Cover any wounds with clean sterilised dressing. Open wounds (unlike intact skin) have high chance of getting infected.
4. Testing for carrier state is not necessary. It will not give any actionable information. Even if the tests are all negative you will need to take some precautions. The pus or discharge from the cellulitis should be already tested by your grandmother’s Doctor. Chances are that there could be some antibiotic resistance already. A complete cure of the cellulitis will only eradicate the bacteria. I assume she already had / currently taking antibiotics for this purpose.
4. Reduce the frequency (or even exclude) of the visits to the grandmother’s place until the eczema lesions are healed and dry , with no steroid use.
5. Avoid cross contact with spoiled dresses, dressings, bandages etc.
So In short, some precautions are needed, but no extreme measure per se. As a mother you will have to take charge here and when it comes to child’s health everyone will understand and cooperate. These precautions need to be continued till the eczema lesions heal. (or the cellultits is contained and well treated).
Hope this helps
Please feel free to ask followup queries