Travellers' diarrhoea. Which antimicrobial?

For those who venture from highly industrialised areas to developing tropical and semitropical areas, the chance of developing diarrhoea is about 40%. In most cases a bacterial pathogen is responsible for the illness. The antimicrobial agents with the greatest activity against these organisms are cotrimoxazole (trimethoprim/sulfamethoxazole) during the summer months in the interior of Mexico (a region where this agent has been studied extensively), and the fluoroquinolones for other places or other times, until data become available to indicate the appropriateness of cotrimoxazole here as well. Persons at risk should take along with them a drug to treat symptoms of travellers' diarrhoea, and an appropriate antimicrobial agent. At the passage of the third unformed stool, it is recommended that travellers treat themselves with fluids and salt (flavoured mineral water augmented with saltine crackers is sufficient in most cases), symptomatic treatment and antibacterial therapy. Of these, the antimicrobial is the most important component, which is given either as a single large dose or one or twice daily for 3 days. Perhaps optimal therapy for afebrile nondysenteric patients is loperamide in combination with the antibacterial drug. In the face of fever or dysentery, the antimicrobial should be used alone. In special situations where food and beverage restrictions cannot be followed and where the itinerary cannot tolerate even the slightest alterations because of illness, chemoprophylaxis can be considered. The most effective preventive medication in this case is the antimicrobial also used for therapy, taken in half the therapeutic dosage daily while in the area of risk. However, the majority of travellers should not use this approach.(ABSTRACT TRUNCATED AT 250 WORDS)