You re best taking out the grout and re grouting it, as I have been supervising the cleaning of houses for many years and if you have the mould spots in the grout, they never really come out....the other alternative is to use neat bleach and a scrubbing brush and clean the area with that and then just take out the grout which is too far gone to bleach. Bleach kills the mould spores. Mould should never be left so long that you have to do drastic action as mould spores can kill, especially someone who is asthmatic. Care must be used when using the bleach, use in a well ventilated room, use a mask over the nose and mouth, cover your clothes as it will bleach them, so wear old clothes. You will not have instant results, you will have to wait 10 minutes, then go back and have a look and wash off the bleach and leave to dry.
You re best taking out the grout and re grouting it, as I have been supervising the cleaning of houses for many years and if you have the mould spots in the grout, they never really come out....the other alternative is to use neat bleach and a scrubbing brush and clean the area with that and then just take out the grout which is too far gone to bleach. Bleach kills the mould spores. Mould should never be left so long that you have to do drastic action as mould spores can kill, especially someone who is asthmatic. Care must be used when using the bleach, use in a well ventilated room, use a mask over the nose and mouth, cover your clothes as it will bleach them, so wear old clothes. You will not have instant results, you will have to wait 10 minutes, then go back and have a look and wash off the bleach and leave to dry.