So You Actually Drank the Water During Your Vacation?

- June 20, 2015

Published: Jun 20, 2015

By Christina Shenvi MD, PhD

Along with summer comes travel, and with travel comes traveler's diarrhea (TD). Here is a look at ciprofloxacin, particularly as it pertains to this troublesome summertime ailment.

Traveler's diarrhea occursin up to 40% to 50% of travelers. The risk of acquiring it depends on the travel destination, the history, and immune status of the traveler, and the style of travel. Travelers to the Middle East, southern Asia, Africa, Central America, and South America have the highest risk. Individuals who stay at resorts have a lower risk of TD than backpackers or those who are more adventuresome in their sampling of the local cuisine from street vendors. Patients who are on acid-suppressing medications are also at higher risk of acquiring TD, as the acidic stomach environment provides a natural mechanism for reducing infection from ingested bacteria.

The majority of TD (50% to 80% of cases) is attributable to bacteria and bacterial toxins. Viruses, protozoa, and helminths make up the remaining cases. Of bacterial causes, enterotoxigenic E. coli predominate in Africa and South Asia, while other E. coli species cause the majority of cases in Latin America, and Campylobacter is top of the list in Southeast Asia. 90% of cases occur within the first 2 weeks of travel.

Treatment of TD

The recommended treatment for mild cases is hydration and rest. Loperamide, which has anti-motility and anti-secretory effects, can be used for a short period of time. However it should not be used in children, and should be avoided in patients with evidence of invasive infections, such as those with bloody stools or fevers. In moderate to severe cases, antibiotics can be effective to reduce the course of the illness. Ciprofloxacin is a first-line agent. Campylobacter in Southeast Asia have high rates of ciprofloxacin resistance, in which case azithromycin is an alternative.

How It Works

Like other fluoroquinolones, ciprofloxacin inhibits bacterial DNA gyrase and topoisomerase IV. It is bactericidal, and active against Gram positive and Gram negative bacteria.

Notable History

Ciprofloxacin was developed by Bayer Pharmaceuticals in 1983, and gained FDA approval in 1987. It contains only one additional carbon atom compared with norfloxacin, but has considerably higher potency for a number of different bacteria. In 2000, ciprofloxacin was the first antimicrobial approved by the FDA for a biological attack; its indication for post-exposure inhalational anthrax was used to justify stockpiling of the medication after the 2001 anthrax mailings.

Scope of Use

Antibiotic prophylaxis is not recommended for the general public, since the illness is generally mild, and its course can be shortened by treatment after symptoms have begun. However prophylaxis with ciprofloxacin is recommended in certain travelers, particularly those who will be ex-patria for a short period of time and need to maintain their health (politicians or athletes), as well as in those with chronic illnesses, underlying GI problems (such as inflammatory bowel disease), or who are immunocompromised in whom a bout of TD could pose a serious threat. For prevention, a dose of 250-500 mg daily for a maximum of 3 weeks can prevent 80% to 90% of TD cases.

Dosing and Adjustments

For TD, Cipro can be given as a single dose of 500 mg, or as 500 mg BID for 3 days in more severe cases. Treatment can reduce the duration of disease from several days to about 1 day. In regions of high Campylobacter prevalence, azithromycin should be used instead.

Adverse Events

While there is some concern that treatment with a quinolone could increase the release of Shiga-toxin by certain strains of E. coli and thereby increase the risk of hemolytic uremic syndrome, Shiga-toxin-releasing E. coli are not a common cause of TD, so the risk is small. Treatment with any antibiotic could increase the risk of subsequent C. diff-associated diarrhea as well.

Cost

Twenty 500-mg ciprofloxacin tablets are available on the $4-list at both Target and Walmart, making ciprofloxacin an affordable medication for most patients.

Christina Shenvi, MD, PhD is an assistant professor in the department of emergency medicine at the University of North Carolina. A version of this article originally appeared at Emergency Physicans Monthly.