Doxycycline prophylaxis of travelers' diarrhea in Honduras, an area where resistance to doxycycline is common among enterotoxigenic Escherichia coli.

ABSTRACT

PIP: This study analyzed the effect of doxycycline prophylaxis of travelers' diarrhea in Honduras, an area where antibiotic resistance is common among enterotoxigenic Escherichia coli (ETEC). 44 newly arrived US Peace Corps volunteers were given either 100 mg of doxycycline/day or a placebo. All 22 subjects who received a placebo developed travelers' diarrhea within 3 weeks compared to 7 of 22 subjects (32%) who received doxycycline. ETEC were isolated from 39% of the travelers' diarrhea episodes. In the placebo group, ETEC from 7 of 13 stool samples (54%) were resistant to doxycycline. In the doxycycline group, ETEC from 10 of 11 stool samples (91%) were resistant. Volunteers who took doxycycline had a shorter diarrheal illness than controls and a less severe disease, as measured by the peak numberof stools/day. No clinical adverse drug effects were noted. The protective effect of the drug lasted only while the drug was being taken. This study demonstrates that prophylactic doxycycline significantly reduces the severity of illness among those who experience travelers' diarrhea and can provide a 60-70% protection rate even in countries where ETEC are resistant to antibiotics. Antibiotic prophylasix should be viewed as a temporary measure, however, until safer and perhaps more effective methods such as vaccines or nonpharmacologic agents become available.