Antibiotic prophylaxis

• There is evidence that prophylactic antibiotics are effective in preventing traveller's diarrhoea, given that bacterial infection is a major cause of this condition.
• However, the World Health Organization (WHO) warns that the use of prophylactic antibiotics is controversial (with some experts not recommending this [NIH Consensus Development Program, 1985; Thielman and Guerrant, 2004]), although WHO acknowledges that there is a role for their use in travellers with increased susceptibility to infection and for those individuals on critical missions [WHO, 2009].
• This is supported by US guidelines [Hill et al, 2006; CDC, 2009] which also recommend that antibiotic prophylaxis should not be routinely prescribed because:
• Antibiotic prophylaxis offers no protection against non-bacterial causes of traveller's diarrhoea (such as viruses and parasites).
• For most people, traveller's diarrhoea is mild and self-limiting.
• Self-treatment with a short course of antibiotics (up to 3 days) can reduce the duration of traveller's diarrhoea.
• Taking antibiotic prophylaxis may give the traveller a false sense of security, which might lead to neglect of food and water precautions.
• The increasing prevalence of antibiotic resistance is of concern (including to fluoroquinolones [Hakanen et al, 2003; Ruiz et al, 2007; Vlieghe et al, 2008]).
• Antibiotic treatment can lead to adverse effects.
• Reports of Clostridium difficile infection (which can be potentially life-threatening) have been reported for people taking antibiotics for the treatment of traveller's diarrhoea [Norman et al, 2008]. The risk of C. difficile infection is increased in people taking a longer course of antibiotics (such as for prophylaxis).
• Other adverse effects associated with antibiotics include gastrointestinal symptoms (such as diarrhoea), allergic reactions, vaginal thrush, and sun sensitivity (associated with quinolones).
• There is no evidence to support the effectiveness of antibiotic prophylaxis for people travelling to countries with low or intermediate risk of traveller's diarrhoea.
• One double-blind trial in 127 participants found antibiotic treatment (norfloxacin) to be effective in reducing the number of Swedish travellers developing diarrhoea in high-risk countries (Africa, Asia, or Latin America, p = 0.0004) but not for those travelling to low-risk countries (Mediterranean Europe or the Canary Islands) [Wiström et al, 1987].
• No antibiotics are licensed in the UK for the prophylaxis of traveller's diarrhoea.

Groups considered for antibiotic prophylaxis

• The groups of travellers for whom antibiotic prophylaxis is recommended are in line with recommendations issued by WHO, with guidelines from the US and Canada [Public Health Agency of Canada, 2001; Hill et al, 2006; CDC, 2009; WHO, 2009], and expert opinion [Ericsson, 2003; Al-Abri et al, 2005; Welsby, 2005; Castelli et al, 2006; Bhadelia et al, 2007; DuPont, 2008; Hill and Ryan, 2008; DuPont et al, 2009b].

People on acid-suppressive therapy

• Although people on acid-suppressive therapy (such as proton pump inhibitors) are at increased risk of traveller's diarrhoea, the majority of CKS expert reviewers recommend that antibiotic prophylaxis should not be offered routinely to this group unless they have a high risk of complications (for example, if they are immunocompromised).

Empirical antibiotics for treatment of traveller's diarrhoea

• There is evidence from a Cochrane systematic review supporting the use of antibiotics for treating traveller's diarrhoea [de Bruyn et al, 2000]. Secondary outcomes indicate that antibiotics are more effective than placebo at increasing the number of people cured after 72 hours and at reducing the severity of diarrhoea. However, antibiotic treatment was associated with more adverse effects than placebo.
• Antibiotic treatment usually limits the duration of illness by an average of about 1 day (for further information, see the evidence on Antibiotic treatment) [WHO, 2009].

Indication for empirical antibiotic treatment

• The recommendation to offer empirical treatment to people travelling to high-risk regions where medical assistance is poor or limited is in line with the recommendation from WHO. WHO recommends that antibiotic treatment should be used where there is no medical help available and if bowel movements become 'very frequent, very watery or contain blood, or last beyond 3 days' [WHO, 2007].