We must take these recommendations and suggestions using a pinch of salt because, [1] its always difficult to clinically diagnose dehydration as 5%,10% or more based on clinical examination. (2) These are not new antibiotics but the one used in the last 20-30 years.
Advising to wait for patient to stop vomiting before commencing treatment is difficult as any patient with ten or more percent dehydration is likely to be very ill. No doctor living on earth will wait to institute treatment.
The only fact which we must give importance is to emphasis on using the correct dose based on body surface area or weight. These bacteria cause more harm when the dose of antibiotic is low because the antibiotic will kill good bacteria and these bad ones will develop resistance fast and make the patient chronic carrier. The main problem of giving adequate dose as this will increase the cost of care and also side effects which is often difficult to tolerate.