Doxycycline Malaria Prophylaxis Impact on Risk of Travelers' Diarrhea among International Travelers

Doxycycline as an antimalarial: Impact on travellers' diarrhoea and doxycycline resistance among various stool bacteria - Prospective study and literature review

BACKGROUND

Antibiotics predispose travellers to acquire multidrug-resistant bacteria, such as extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-PE). Although widely used in antimalarial prophylaxis, doxycycline has scarcely been studied in this respect.

METHODS

We explored the impact of doxycycline on rates of traveller's diarrhoea (TD), ESBL-PE acquisition and, particularly, doxycycline co-resistance among travel-acquired ESBL-PE in a sample of 412 visitors to low- and middle-income countries. We reviewed the literature on traveller studies of doxycycline/tetracycline resistance among stool pathogens and the impact of doxycycline on TD rates, ESBL-PE acquisition, and doxycycline/tetracycline resistance.

RESULTS

The TD rates were similar for doxycycline users (32/46; 69.6%) and non-users (256/366; 69.9%). Of the 90 travel-acquired ESBL-PE isolates, 84.4% were co-resistant to doxycycline: 100% (11/11) among users and 82.3% (65/79) among non-users. The literature on doxycycline's effect on TD was not conclusive nor did it support a recent decline in doxycycline resistance. Although doxycycline did not increase ESBL-PE acquisition, doxycycline-resistance among stool pathogens proved more frequent for users than non-users.

CONCLUSIONS

Our prospective data and the literature review together suggest the following: 1) doxycycline does not prevent TD; 2) doxycycline use favours acquisition of doxy/tetracycline-co-resistant intestinal bacteria; 3) although doxycycline does not predispose to travel-related ESBL-PE acquisition per se, it selects ESBL-PE strains co-resistant to doxycycline; 4) doxycycline resistance rates are high among stool bacteria in general with no evidence of any tendency to decrease.

Bacterial travellers' diarrhoea: A narrative review of literature published over the past 10 years

Travellers' diarrhoea (TD) is the most frequent illness experienced by international travellers to lower-income countries with bacterial agents considered to account for 80-90% of cases. In this review, we summarise evidence published on bacterial TD over the past 10 years, focusing on the epidemiology and aetiology of TD. Diarrhoeagenic Escherichia coli (DEC) continue to be the most commonly implicated bacteria in TD, although Enteropathogenic E. coli (EPEC) and Enteroaggregative E. coli (EAEC) now appear to be predominant where Enterotoxigenic E. coli (ETEC) was previously considered most prevalent globally. Where fluroquinolone resistance had primarily been documented for Campylobacter in Southeast Asia, widespread resistance has been observed in most regions of the world for multiple enteropathogens, including Shigella, Salmonella, ETEC and EAEC. Implementation of novel molecular methods for pathogen detection has led to identification of bacterial pathogens, including Clostridium difficile (with and without the use of prior antibiotics), Arcobacter species and Bacteroides fragilis, as aetiological agents in TD. The widespread resistance to first-line antibiotics in multiple bacterial enteropathogens warrants continued surveillance and re-evaluation of current treatment practices. Further investigations are required to determine the prevalence and geographical distribution of bacterial enteropathogens that have been more recently implicated in TD.

What's new in travellers' diarrhoea: updates on epidemiology, diagnostics, treatment and long-term consequences

BACKGROUND

Travellers' diarrhoea (TD) is the most common clinical syndrome affecting travellers. This narrative review summarizes key discoveries reported in the last two years related to TD and suggests areas for future research.

METHODS

A PubMed literature search was conducted for novel data in TD research published between 12 January 2018 and 12 January 2020. Inclusion was based on contribution to epidemiology, aetiology, diagnostics, management and long-term consequences and relevance to public health, discovery and clinical practice.

RESULTS

The initial literature search yielded 118 articles. We retrieved 72 and reviewed 31 articles for inclusion. The findings support our understanding that TD incidence varies by traveller group and environment with students and military-travel remaining moderately high risk, and control of food and water in mass gathering events remain an important goal. The growth of culture-independent testing has led to a continued detection of previously known pathogens, but also an increased detection frequency of norovirus. Another consequence is the increase in multi-pathogen infections, which require consideration of clinical, epidemiological and diagnostic data. Fluoroquinolone resistant rates continue to rise. New data on non-absorbable antibiotics continue to emerge, offering a potential alternative to current recommendations (azithromycin and fluoroquinolones), but are not recommended for febrile diarrhoea or dysentery or regions/itineraries where invasive pathogens are likely to cause illness. Recent studies investigated the interaction of the microbiome in TD prevention and consequences, and while discriminating features were identified, much uncertainty remains. The prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) acquisition and carriage is increasing. Finally, continued research documents the post-infectious consequences, whereas mechanisms of reactive arthritis and post-infectious IBS necessitate further investigation.

CONCLUSIONS

Globally, TD remains an important travel health issue and advances in our understanding continue. More research is needed to mitigate risk factors where possible and develop risk-based management strategies to reduce antibiotic usage and its attendant consequences.

Travel-Related Behaviors and Health Outcomes of Adolescents Compared with Adults on Short-Term International Service Missions

With an increasing number of adolescents participating in international travel, little is known about travel-related behaviors and health risks in this age group. In the years 2015-2016, we conducted an anonymous, posttravel, questionnaire-based survey with the aim to compare self-reported practices and travel-related symptoms between adolescents (< 18 years old, N = 87) and adults (≥ 18 years old, N = 149) who came to our travel clinic before their humanitarian missions. They had the same pretravel health education, and traveled together to perform similar activities. In univariate analysis, compared with adults, we found that adolescents reported less prior international travel (P < 0.001), more often wore long-sleeved clothing for malaria prevention (P < 0.001) but less often for sun protection (P = 0.009), more often used insect repellents (P = 0.011), and less often had diarrhea (P = 0.024). All other practices and health outcomes were similar between the groups. Multivariate analyses using Bayesian network show strong associations between adults and prior travel experience, and not wearing long-sleeve clothing for malaria prevention. We also found strong associations between prior international travel and sustaining an injury, and having jet lag, as well as between taking malaria prophylaxis and not having diarrhea. Overall, most practices and health outcomes were similar between age groups. Adolescent age and lack of prior international travel experience did not have significant impacts on practices and health outcomes. Our findings highlight the need for more effective strategies to improve the behaviors and health outcomes in both adolescents and adults.

Clinical and Epidemiological Changes in French Soldiers After Deployment: Impact of Doxycycline Malaria Prophylaxis on Body Weight

BACKGROUND

Antibiotics are growth promotors used in animal farming. Doxycycline (DOXY) is a tetracycline antibiotic taken daily and continued 1 month after return to protect against malaria during travel and deployment in endemic areas. We evaluated DOXY impact on body weight in military international travelers.

MATERIEL AND METHODS

A prospective cohort analysis was conducted in 2016-2018, recruiting 170 French soldiers before a 4-month assignment overseas. Many clinical data including anthropometric measures by an investigator were collected before and after deployment. Weight gain was defined by an increase of 2% from baseline. The study protocol was supported by the French Armed Forces Health Services and approved by the French ethics committee (IRB no. 2015-A01961-48, ref promoter 2015RC0). Written, informed consent was obtained with signature from each volunteer before inclusion.

RESULTS

After deployment, 84 soldiers were followed up. Overall, 38/84 (45%) were deployed to Mali with DOXY malaria prophylaxis, and others were deployed to Iraq or Lebanon without malaria prophylaxis according to international recommendations. Body weight increased in 24/84 (30%), of whom 14/24 (58%) were exposed to DOXY. In bivariate analysis, DOXY had a positive but not significant effect on weight gain (P-value = .4). In the final logistic regression model (Fig. 3), weight gain after deployment positively correlated with an increase in waist circumference (odds ratio [OR] 1.23 with 95% CI [1.06-1.47]) suggesting fat gain; with sedentary work (OR 5.34; 95% CI [1.07-31.90]); and with probiotic intake (OR 5.27; 95% CI [1.51-20.40]). Weight impact of probiotics was more important when associated with DOXY intake (OR 6.86; 95% CI [1.52-38.1]; P-value = .016).

CONCLUSIONS

Doxycycline (DOXY) malaria prophylaxis during several months did not cause significant weight gain in soldiers. Further studies are required in older and less sportive traveling populations, and to investigate a cumulative effect over time and recurrent DOXY exposure. Doxycycline (DOXY) may enhance other growth-promoting factors including fatty food, sedentariness, and strain-specific probiotics contained in fermented dairy products which are also used as growth promotors.

Gut Microbiota in Military International Travelers with Doxycycline Malaria Prophylaxis: Towards the Risk of a Simpson Paradox in the Human Microbiome Field

Dysbiosis, developed upon antibiotic administration, results in loss of diversity and shifts in the abundance of gut microbes. Doxycycline is a tetracycline antibiotic widely used for malaria prophylaxis in travelers. We prospectively studied changes in the fecal microbiota of 15 French soldiers after a 4-month mission to Mali with doxycycline malaria prophylaxis, compared to changes in the microbiota of 28 soldiers deployed to Iraq and Lebanon without doxycycline. Stool samples were collected with clinical data before and after missions, and 16S rRNA sequenced on MiSeq targeting the V3-V4 region. Doxycycline exposure resulted in increased alpha-biodiversity and no significant beta-dissimilarities. It led to expansion in Bacteroides, with a reduction in Bifidobacterium and Lactobacillus, as in the group deployed without doxycycline. Doxycycline did not alter the community structure and was specifically associated with a reduction in Escherichia and expression of Rothia. Differences in the microbiota existed at baseline between military units but not within the studied groups. This group-effect highlighted the risk of a Simpson paradox in microbiome studies.