Michael Pichichero and colleagues at the University of Rochester Medical Center here studied 1,080 children aged 2-18 years who had tonsillopharyngitis (tonsillitis accompanied with a sore throat) caused by streptococcus bacteria, reported the online edition of health magazine WebMD.
The kids were treated at a private medical centre and each received one of nine different antibiotics to cure the infection.
However, symptoms of the infection returned in 17 percent of the children within 20 days of completing antibiotic treatment.
The relapse rate varied among the antibiotics, ranging from 7-25 percent. Based on the results, tonsillopharyngitis relapse is "not an uncommon event", said Pichichero.
The researchers said keeping one's hands clean was an important measure to prevent the spread of viruses and bacteria that cause tonsillitis.
"When you're washing your hands, lather up with soap and clean water (warm water, if possible) for 20 seconds. That's how long it takes to sing the traditional 'Happy Birthday' song twice," said one of the researchers.
"Also, avoid prolonged contact with anyone who has a sore throat and has not been taking antibiotics for at least 24 hours," warned Pichichero.