Antibiotics For Traveler's Diarrhea: Best Treatment Options

Traveler's diarrhea is the most common travel-related illness, affecting 20-50% of people who travel to certain destinations. It is caused by bacterial, viral, and parasitic infections, with bacteria being the most common cause. The most common bacterial cause is enterotoxigenic Escherichia coli, followed by Campylobacter jejuni, Shigella, and Salmonella species. The most common viral cause is norovirus, and the most common parasitic cause is Giardia.

The best antibiotic for traveler's diarrhea depends on the cause of the infection, the severity of the illness, and the region where the traveler is visiting. Antibiotics are not recommended for mild cases of traveler's diarrhea. For moderate cases, azithromycin is the preferred antibiotic, but fluoroquinolones may also be used if the traveler is not going to Southeast or South Asia, where Campylobacter resistance is common. For severe cases, azithromycin is the preferred antibiotic, but fluoroquinolones may be used for severe, non-dysenteric diarrhea if the traveler is not going to an area with a high risk of invasive pathogens.

Antibiotics for treatment

Antibiotics are an effective treatment for traveller's diarrhea, reducing the duration of the illness by 1-2 days. However, they are not recommended for mild cases, and there are concerns about the use of antibiotics leading to antibiotic resistance and the acquisition of multidrug-resistant bacteria. Antibiotics are recommended for moderate to severe cases.

The choice of antibiotic depends on the likely pathogen and the region travelled to, as resistance varies by region. Fluoroquinolones (e.g. ciprofloxacin, levofloxacin) have traditionally been the first-line treatment, but resistance is now common, especially in South and Southeast Asia. Azithromycin is an alternative, with limited global resistance, and a more favourable safety profile compared to fluoroquinolones. Rifaximin is another alternative, but it is not effective against invasive pathogens such as Campylobacter, Shigella and Salmonella.

Antibiotics can be combined with an antimotility agent such as loperamide, which can be used on its own to treat mild traveller's diarrhea.

Prophylaxis without antibiotics

The use of antibiotic prophylaxis for TD prevention in travelers is still controversial, mainly because of the challenge of managing risks and benefits. Many factors, such as emerging drug resistance, side effects, cost, and risk behavior need to be considered.

Bismuth subsalicylate (BSS) is the primary agent studied for the prevention of TD, other than antibiotics. It has been shown to have mild antimicrobial activity as well as antisecretory and anti-inflammatory properties. BSS commonly causes blackening of the tongue and stool and can cause constipation, nausea, and rarely tinnitus. It should be avoided by children under the age of 3 years and by persons allergic to salicylates, and caution is advised for patients taking other salicylate-containing medications or anticoagulants.

Lactobacillus preparations have also been used for the prevention of TD, in the hope of interfering with the colonization of the gastrointestinal tract by pathogenic organisms. However, their effectiveness has been limited, with reported protective efficacy ranging from zero to 47%.

Probiotics (e.g., Lactobacillus GG, Saccharomyces boulardii) have been studied in small numbers of people as TD prevention, but results are inconclusive, partly because standardized preparations of these bacteria are not reliably available.

Bovine colostrum has been anecdotally reported to be beneficial as a daily prophylaxis agent for TD. However, commercially sold preparations of bovine colostrum marketed as dietary supplements are not approved by the US Food and Drug Administration (FDA). Because no data from rigorous clinical trials demonstrate efficacy, insufficient information is available to recommend the use of bovine colostrum to prevent TD.

Prophylaxis with antibiotics

The choice of antibiotic for prophylaxis has changed over the years due to the development of antibiotic resistance. Older studies found that doxycycline, trimethoprim-sulfamethoxazole, and fluoroquinolones were effective in preventing traveller's diarrhea. However, resistance to these antibiotics has since emerged, particularly among Campylobacter and Shigella species. More recent studies have investigated the use of rifaximin, a non-absorbable antibiotic, which has been shown to be effective in preventing traveller's diarrhea with minimal side effects.

When used as prophylaxis, antibiotics should be taken daily as a single dose while in an area of risk and continued for 1-2 days after leaving. The duration of prophylaxis should generally be less than 3 weeks to minimise the risk of antibiotic resistance and adverse reactions.

The decision to use prophylactic antibiotics should be made on a case-by-case basis, considering the traveller's risk factors, destination, and the potential benefits and risks of antibiotic use.

Food and beverage selection

• Choose food and drinks carefully: Eat only foods that are cooked and served hot. Avoid food that has been sitting on a buffet or left out for a long time. Eat raw fruits and vegetables only if you have washed them in clean water or peeled them.
• Drink sealed beverages: Only consume beverages from factory-sealed containers and avoid ice made from unclean water.
• Be cautious with water: Do not use tap water for drinking, brushing teeth, or mixing baby formula. Use boiled water (boiled for at least 5 minutes) for mixing formula. Bottled drinks are generally safe if the seal is intact.
• Avoid high-risk foods: Do not consume raw or undercooked meat or shellfish, raw leafy vegetables, or food from street vendors.
• Breastfeed infants: For infants, breastfeeding is the best and safest food source. However, travelling may reduce milk production due to stress.
• Wash and peel produce: Wash all fruits and vegetables before eating. If possible, peel fresh produce like tomatoes and watermelons (which may be injected with water to increase weight).
• Be cautious with dairy: Drink only pasteurized milk. Dairy products may worsen symptoms of traveller's diarrhea.
• Monitor children: Keep children from putting things in their mouths or touching dirty items and then their mouths. If possible, prevent infants from crawling on dirty floors
• Check utensils and dishes: Ensure that utensils and dishes are clean before use.

These precautions can help reduce the risk of traveller's diarrhea, but they may not always be foolproof. The best approach is to combine these food and beverage selection strategies with other preventive measures, such as frequent handwashing and maintaining good hygiene practices.

Antimotility agents

The most effective antimotility agents are synthetic opiates, such as diphenoxylate with atropine (Lomotil) and loperamide (Imodium). Loperamide is the preferred option as it has little to no central opiate effects and is more gut-specific than diphenoxylate. It also has antisecretory properties and reduces the number of stools passed and the duration of diarrhea. It is safe to use in conjunction with antibiotics, even in cases of invasive pathogens.

Frequently asked questions