Thymidine-requiring Haemophilus influenzae and Staphylococcus aureus [letter].

In the past year we have isolated thy- Staphylococcus aureus from the 
sputum of four children with cystic fibrosis who were receiving co-trimoxazole, 
and lately we have isolated a thy- strain of Haemophilus influenzae 
from a patient with cystic fibrosis also receiving co-trimoxazole. In view 
of the exacting growth requirements of H. influenzae we feel that 
thy- strains might easily be overlooked or assumed to have died 
when they fail to grow on sensitivity-test media. 