Most common cause of acute epiglottitis in children is:

Hemophilus influenzae type B REF: P L Dhingra 4th edition page 266, 399 "Acute epiglottitis in children is caused by Hemophilus influenzae type B. It produces a typical "Thumb sign" on lateral X-ray film. Ampicillin was considered the drug of choice but now many organisms have become resistant to it and ceftriaxone is preferred" "It is a serious condition and affects children of 2-7 years of age but can also affect adults H. influenzae B is the most common organism responsible for this condition in children"