The recovery of bacteria from the handpiece of a high school telephone.

The purpose of the experiment reported in this paper was to study the bacteria on the public telephones at Montgomery Blair High School in Silver Spring, Maryland, to determine if there is a risk of infection to students who use the phones. Five phone handpieces from around the school--from four public phones and the principal's phone--were swabbed twice, at 7 a.m. and at 3 p.m., on November 6,2000. Three sites on each handpiece were swabbed: the mouthpiece, the handle, and the earpiece. The swabs were streaked onto media supportive of aerobic-bacteria growth and incubated at 5 percent carbon dioxide for 24 and 48 hours at 37 degrees C. The plates were studied for quantitative and qualitative data. Microscopic examination of Gram-stain preparations and, in some cases, biochemical identification were performed on the bacterial isolates. Results showed an increase in the number of bacteria from morning to afternoon in specimens from 10 of the 15 observations (67 percent). Eight of these 10 observations found more than threefold increases in the number of bacteria. In the afternoon, more types of bacteria were found in eight of the 15 specimens. Only one specimen had decreases in the number and types of bacteria from morning to afternoon. None of the bacteria that were found, however, were known pathogens. The authors conclude that even though more bacteria were recovered from phones in the afternoon than in the morning, their study did not show a serious health risk to students who used the public telephones on the day of the experiment.