Empirical antimicrobial therapy for traveler's diarrhea

Trial Evaluating Ambulatory Therapy of Travelers' Diarrhea (TrEAT TD) Study: A Randomized Controlled Trial Comparing 3 Single-Dose Antibiotic Regimens With Loperamide

Background

Recommended treatment for travelers' diarrhea includes the combination of an antibiotic, usually a fluoroquinolone or azithromycin, and loperamide for rapid resolution of symptoms. However, adverse events, postdose nausea with high-dose azithromycin, effectiveness of single-dose rifaximin, and emerging resistance to front-line agents are evidence gaps underlying current recommendations.

Methods

A randomized, double-blind trial was conducted in 4 countries (Afghanistan, Djibouti, Kenya, and Honduras) between September 2012 and July 2015. US and UK service members with acute watery diarrhea were randomized and received single-dose azithromycin (500 mg; 106 persons), levofloxacin (500 mg; 111 persons), or rifaximin (1650 mg; 107 persons), in combination with loperamide (labeled dosing). The efficacy outcomes included clinical cure at 24 hours and time to last unformed stool.

Results

Clinical cure at 24 hours occurred in 81.4%, 78.3%, and 74.8% of the levofloxacin, azithromycin, and rifaximin arms, respectively. Compared with levofloxacin, azithromycin was not inferior (P = .01). Noninferiority could not be shown with rifaximin (P = .07). At 48 and 72 hours, efficacy among regimens was equivalent (approximately 91% at 48 and 96% at 72 hours). The median time to last unformed stool did not differ between treatment arms (azithromycin, 3.8 hours; levofloxacin, 6.4 hours; rifaximin, 5.6 hours). Treatment failures were uncommon (3.8%, 4.4%, and 1.9% in azithromycin, levofloxacin, and rifaximin arms, respectively) (P = .55). There were no differences between treatment arms with postdose nausea, vomiting, or other adverse events.

Conclusions

Single-dose azithromycin, levofloxacin, and rifaximin with loperamide were comparable for treatment of acute watery diarrhea.

Clinical Trial Registration

NCT01618591.

Antibiotic treatment of acute gastroenteritis in children

Antibiotic therapy is not necessary for acute diarrhea in children, as rehydration is the key treatment and symptoms resolve generally without specific therapy. Searching for the etiology of gastroenteritis is not usually needed; however, it may be necessary if antimicrobial treatment is considered. The latter is left to the physician evaluation in the absence of clear indications. Antimicrobial treatment should be considered in severely sick children, in those who have chronic conditions or specific risk factors or in specific settings. Traveler’s diarrhea, prolonged diarrhea, and antibiotic-associated diarrhea may also require antibiotic therapy. Depending on the severity of symptoms or based on risk of spreading, empiric therapy may be started while awaiting the results of microbiological investigations. The choice of antibiotic depends on suspected agents, host conditions, and local epidemiology. In most cases, empiric therapy should be started while awaiting such results. Empiric therapy may be started with oral co-trimoxazole or metronidazole, but in severe cases parenteral treatment with ceftriaxone or ciprofloxacin might be considered.

Travelers with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is the most common genetic disease among persons with African ancestry. This article provides a background to SCD and reviews many important aspects of travel preparation in this population.

METHODS

The medical literature was searched for studies on travel-associated preparedness and complications in individuals with SCD. Topics researched included malaria, bacterial infections, vaccinations, dehydration, altitude, air travel, and travel preparedness.

RESULTS

There is very little published literature that specifically addresses the risks faced by travelers with SCD. Rates of medical complications during travel appear to be high. There is a body of literature that describes complications of SCD in indigenous populations, particularly within Africa. The generalizability of these data to a traveler is uncertain. Combining these sources of data and the broader medical literature, we address major travel-related questions that may face a provider preparing an individual with SCD for safe travel.

CONCLUSIONS

Travelers with SCD face considerable medical risks when traveling to developing tropical countries, including malaria, bacterial infections, hypovolemia, and sickle cell-associated vaso-occlusive crises. For individuals with SCD, frank counseling about the risks, vigilant preventative measures, and contingency planning for illness while abroad are necessary aspects of the pre-travel visit.

Impact and management of Campylobacter in human medicine--US perspective

Viruses, enteric bacteria and parasites can all produce similar syndromes of acute enteritis, although the pathophysiology and molecular pathogenesis may vary widely. The severity of acute enteritis varies greatly, and only a small fraction of cases undergo medical evaluation. There are over 200 000 000 episodes of acute enteritis annually in the USA, of which approximately 75 000 000 are foodborne. Fewer than 20% of estimated cases have a known etiology. Nearly half of the more than 4 000 000 cases of known foodborne bacterial enteritis are attributed to Campylobacter infections. The FoodNet active population-based surveillance system has demonstrated geographic variation in the incidence of Campylobacter infection, and generally declining incidence since 1996. Campylobacter jejuni infections vary in severity and duration. Antimicrobial therapy, especially if administered early, may hasten clinical resolution by 2-3 days. Therapy is generally restricted to individuals with moderate-to-severe disease and high-risk individuals (underlying immunodeficiency, chronic illness, extremes of age, etc.). Approximately 10-15% of C. jejuni isolates are fluoroquinolone resistant, although most strains are macrolide susceptible. Several acute intra-abdominal as well as extraintestinal complications can occur following C jejuni enteritis, although bacteremia and metastatic infection are rare, except in high-risk patients. Post-infectious syndromes include post-dysenteric bowel dysfunction, the less frequent but more severe reactive arthritis (1%), and Guillain-Barre syndrome (0.1%). The recent demonstration that antibiotic administration for Escherichia coli O157:H7 hemorrhagic enteritis increases the risk of hemolytic-uremic syndrome 5-10-fold forces reconsideration of empirical broad-spectrum antibiotic therapy for acute hemorrhagic enteritis, and supports narrow-spectrum erythromycin therapy for acute enteritis.

Diarrhoea during military deployment: current concepts and future directions

PURPOSE OF REVIEW

Diarrhoea among military travellers deployed globally in conflict and peacekeeping activities remains one of the most important health threats. Here we review recent advances in our understanding of the epidemiology, laboratory identification, treatment and chronic health consequences of this multi-cause infection, and consider the implications for public health management and future research.

RECENT FINDINGS

The incidence of diarrhoea among deployed military personnel from industrialized countries to lesser developed countries is approximately 30% per month overall, with clinical incidence between 5 and 7% per 100 person-months. The risk appears to be higher early during deployment and is associated with poor hygienic conditions and contaminated food sources. Gaps remain in our understanding of the cause, given the lack of laboratory capability in austere conditions of deployment; however, recent advances in molecular methods of characterization hold promise in improving our detection capabilities. While there have been improvements in understanding of best treatments, more work needs to be done in transforming this knowledge into action and optimizing single-dose antibiotic treatment regimens. Finally, the under-recognized burden of chronic consequences of these infections is gaining awareness and reinforces the need to find effective preventive strategies.

SUMMARY

Our understanding of the epidemiology of diarrhoea is improving but further research is needed to fully account for acute operational-focused health impacts as well as the chronic enduring disease impacts. Improved field diagnostics would be of great value to support these efforts.

Knowledge, attitudes, and practice of travelers' diarrhea management among frontline providers

BACKGROUND

Many studies have found acute gastrointestinal infections to be among the most likely reason for clinic visits among forward deployed soldiers and are considered a significant contributor to morbidity in this population. This occurs despite the controlled food and water distribution systems under which military populations operate. Furthermore, recent studies have indicated that providers often fail to appropriately identify and treat the typical causes of these infections. To adequately address this issue, an assessment of gaps in knowledge, practice, and management of acute diarrhea in deployed troops was conducted.

METHODS

A multiple-choice survey was developed by clinical researchers with expertise in travelers' diarrhea (TD) and provided to a convenience sample of clinical providers with a broad range of training and operational experience. The survey evaluated provider's knowledge of TD along with their ability to identify etiologies of various syndromic categories of acute gastrointestinal infections. Providers were also queried on selection of treatment approaches to a variety of clinical-based scenarios.

RESULTS

A total of 117 respondents completed the survey. Most were aware of the standard definition of TD (77%); however, their knowledge about the epidemiology was lower, with less than 24% correctly answering questions on etiology of diarrhea, and 31% believing that a viral pathogen was the primary cause of watery diarrhea during deployment. Evaluation of scenario-based responses showed that 64% of providers chose not to use antibiotics to treat moderate TD. Furthermore, 19% of providers felt that severe inflammatory diarrhea was best treated with hydration only while 25% felt hydration was the therapy of choice for dysentery. Across all provider types, three practitioner characteristics appeared to be related to better scores on responses to the nine management scenarios: having a Doctor of Medicine or Doctor of Osteopathy degree, greater knowledge of TD epidemiology, and favorable attitudes toward antimotility or antibiotic therapy.

CONCLUSION

Results from this survey support the need for improving knowledge and management of TD among deploying providers. The information from this study should be considered to support the establishment and dissemination of military diarrhea-management guidelines to assist in improving the health of military personnel.

Etiology of diarrhea in young children and patterns of antibiotic resistance in Cambodia

BACKGROUND

Little is known about diarrhea etiology and antibiotic resistance in developing countries where diarrhea is a major public health problem.

METHODS

To describe diarrhea etiology and antibiotic resistance patterns in Cambodia, 600 children aged 3 months to 5 years with acute diarrhea (cases) and 578 children without diarrhea (controls) were enrolled from a hospital in Phnom Penh. Stool samples were collected, and pathogens and antibiotic resistance patterns were described.

RESULTS

The most frequently isolated pathogens in these cases were enteroaggregative Escherichia coli (20%) and rotavirus (26%). Enterotoxigenic E. coli, enteroaggregative E. coli, Shigella, Aeromonas, rotavirus, and adenovirus were statistically significantly associated with diarrhea. Among cases, vomiting was associated with viral infections, whereas bloody stool was associated with Shigella. Enterotoxigenic E. coli isolates were highly resistant to ampicillin, sulfonamides, and tetracycline. Approximately 50% of Campylobacter coli and 30% of Campylobacter jejuni isolates were resistant to nalidixic acid and ciprofloxacin. Over 33% of Salmonella isolates were resistant to ampicillin and tetracycline, and almost 100% of Shigella isolates were resistant to trimethoprim/sulfamethoxazole.

CONCLUSIONS

These data on the etiology of diarrhea and antibiotic resistance patterns in Cambodia will have significant effect on local public health policies and on local resource prioritization practices.

Review article: rifaximin, a minimally absorbed oral antibacterial, for the treatment of travellers' diarrhoea

BACKGROUND

Travellers' diarrhoea, a common problem worldwide with significant medical impact, is generally treated with anti-diarrhoeal agents and fluid replacement. Systemic antibiotics are also used in selected cases, but these may be associated with adverse effects, bacterial resistance and drug-drug interactions.

AIM

To review the clinical evidence supporting the efficacy and safety of the minimally absorbed oral antibiotic rifaximin in travellers' diarrhoea.

METHODS

PubMed and the Cochrane Register of Controlled Clinical Trials (to January 2010) and International Society of Travel Medicine congress abstracts (2003-2009) were searched to identify relevant publications.

RESULTS

A total of 10 publications were included in the analysis. When administered three times daily for 3 days, rifaximin is superior to placebo or loperamide; it is at least as effective as ciprofloxacin in reducing duration of illness and restoring wellbeing in patients with travellers' diarrhoea, both with and without identification of a pathogen, as well as in diarrhoea caused by Escherichia coli infection. Rifaximin demonstrates only minimal potential for development of bacterial resistance and for cytochrome P450-mediated drug-drug interactions, and its tolerability profile is similar to that of placebo.

CONCLUSION

When antibiotic therapy is warranted in uncomplicated travellers' diarrhoea, rifaximin may be considered as a first-line treatment option because of its favourable efficacy, tolerability and safety profiles.

Antimicrobial activity of prulifloxacin tested against a worldwide collection of gastroenteritis-producing pathogens, including those causing traveler's diarrhea

Prulifloxacin, the prodrug of ulifloxacin (active component), is a newer fluoroquinolone with broad activity against enteric and nonenteric gram-negative bacilli. Ulifloxacin and other oral comparator agents were tested for activity against 582 gastroenteritis strains from global surveillance studies. Ulifloxacin was highly active against Escherichia coli, Salmonella spp., Shigella spp., Yersinia spp., Vibrio spp., Aeromonas spp., and Plesiomonas spp. (MIC(50)s and MIC(90)s, or=4 microg/ml). Ciprofloxacin exhibited similar activity but was two- to fourfold less potent. Presently approved for clinical use in certain European countries and Japan, ulifloxacin was the most active of the antimicrobial agents tested against these gastroenteritis-causing pathogens.

Efficacy of pefloxacin in the treatment of patients with acute infectious diarrhoea

OBJECTIVE

To investigate the clinical and bacteriological efficacy of 5- and 7-day pefloxacin therapy in patients with acute infectious diarrhoea.

PATIENTS AND STUDY DESIGN

Eighty-two adult patients with acute infectious diarrhoea were randomly divided into three groups: group 1 (n = 20) received 5 days of treatment with pefloxacin, group 2 (n = 27) was assigned to a 7-day pefloxacin protocol, and group 3 (n = 35) was treated symptomatically. The daily dose of pefloxacin was 400mg orally. Clinical and bacteriological response was analysed on the third, fifth and seventh days of treatment as well as 1 and 4 weeks after the end of treatment. The study was an open-labelled, prospective clinical trial.

RESULTS

In the 47 patients (100%) of both pefloxacin groups a clinical improvement was noted on the third day compared with the control group, where this occurred on day 7. Bacteriological eradication was verified on the fifth day in 18 patients (90%) from group 1 and in 25 patients (93%) from group 2; they all had negative stool cultures 1 and 4 weeks after therapy was completed. Only 22 patients (63%) in the control group had negative stool cultures on the seventh day of treatment, but 4 weeks later all of them were negative.

CONCLUSION

There was no difference in clinical (p = 0.232) and bacteriological (p = 0.972) efficacy between the 5- and 7-day pefloxacin treatment protocols. However, both protocols differed significantly in clinical improvement (p < 0.001) and bacteriological eradication (p = 0.017) from the control group.

Guideline for low-cost antimicrobial use in the outpatient setting

In an effort to increase appropriate prescribing of low-cost antimicrobials in the outpatient setting, an evidence-based guideline was created to identify situations when low-cost medications can be used. A literature search identified relevant clinical trials describing the efficacy of antimicrobials used in the outpatient setting. These were analyzed to identify low-cost medications defined as $15 or less. The information was put into guideline format that includes the level of evidence for recommending the drug and information about cost. Sixteen common infections and their treatments were included in the guideline. The efficacy data were similar for the low-cost and higher-cost antimicrobials for all infections included. We created a low-cost antimicrobial guideline for common infections treated in the outpatient setting. The treatment options have similar efficacy to higher cost medications. This guideline will serve as an information source for providers to help them rapidly determine the low-cost treatments for common infections. In addition, it can serve as a template for the development of similar guidelines in other therapeutic classes. These guidelines should be customized before implementation at other health care organizations, with consideration of local resistance patterns, drug availability and patient factors. The effect of guideline implementation on future prescribing habits and providers' opinions about availability of cost information and subsequent conversations with patients and prescribers of medications deserves further study.

Self-reported description of diarrhea among military populations in operations Iraqi Freedom and Enduring Freedom

BACKGROUND

Infectious diarrhea is among the most common medical problems associated with military deployments and has been reported as a frequent problem for troops currently deployed to Iraq and Afghanistan. Lacking is information describing clinical presentation, risk behaviors, and treatment of travelers' diarrhea in this population.

METHODS

An anonymous cross-sectional survey was conducted among 15,459 US military personnel deployed to Southwest Asia during 2003 to 2004.

RESULTS

Overall, diarrhea was commonly reported (76.8% in Iraq and 54.4% in Afghanistan) and was frequently severe (more than six stools/d) (20.8% in Iraq and 14.0% in Afghanistan) or associated with fever (25.8%), vomiting (18% with diarrhea and 16.5% without), persistent symptoms (>14 d, 9.8%), or chronic symptoms (>30 d, 3.3%). Diarrhea was associated with time spent off military compounds and eating local food. Over 80% of respondents sought care for their symptoms, usually at the lowest echelon of care (field medic), and were most often treated with either loperamide or an antibiotic. Self-treatment with loperamide or Pepto-Bismol was also common and successful with only 9% of self-treated individuals reporting seeking further medical care.

CONCLUSIONS

Infectious diarrhea is a common problem for US military personnel, and associated fevers and vomiting are more common than in past conflicts in the region. As with past studies, time spent off base and local food consumption, both more common in Iraq than Afghanistan, continue to be the most important risk factors for acquiring diarrhea. The majority of soldiers reported seeking care for diarrhea, but appropriate treatment, including self-treatment with over-the-counter medicines, was generally successful. Further studies should be conducted to evaluate appropriate treatment algorithms, including the use of self-treatment, for deployed military personnel.

The epidemiology of travel-associated shigellosis—regional risks, seasonality and serogroups

OBJECTIVES

To give a detailed risk estimate of contracting travel-associated shigellosis in various regions of the world.

METHODS

Data on notifications of travel-associated shigellosis in Sweden 1997-2003 were compared with information on recent travel abroad from a comprehensive database based on telephone interviews with more than 160,000 Swedish travellers.

RESULTS

From the national notification database 2678 patients with travel-associated shigellosis were retrieved. The highest risk of being notified with shigellosis was seen in returning travellers from India and neighbouring countries (318/100,000 travellers), East Africa (219/100,000), West Africa (120/100,000), and North Africa (76/100,000). Data on serogroup was available for 2529 isolates. Shigella sonnei was the most common serogroup (67%), followed by Shigella flexneri (26%), Shigella boydii (5%), and Shigella dysenteriae (3%). A higher risk was seen in children below the age of six, compared to older children and adults and in women compared to men. A distinct seasonal pattern was noted with the highest risk of shigellosis in July-October and the lowest in May.

CONCLUSIONS

Denominator based data on reported travel-associated infections are well suited to give risk estimates per region of infection, that could be used to target high-risk groups for pre-travel advice.

Pathophysiology and impact of enteric bacterial and protozoal infections: new approaches to therapy

Despite numerous scientific advances in the past few years regarding the pathogenesis, diagnostic tools and treatment of infectious enteritis, enteric infections remain a serious threat to health worldwide. With globalization of the food supply, the increase in travel, mass food processing and antibiotic resistance, infectious diarrhea has become a critical concern for both developing and developed countries. Oral rehydration therapy has been cited as the most important medical discovery of the century due to the millions of lives that have been saved. However, statistics concerning diarrhea-induced mortality and the highly underestimated morbidity continue to demonstrate the severity of the problem. A more complete understanding of the pathogenesis of infectious diarrhea and potential new vaccines and effective treatments are badly needed. In addition, public health preventive actions, such as early detection of outbreaks, care with food, water and sanitation and, where relevant, immunization, should be considered a priority. This article provides an overview of the epidemiological impact, pathogenesis and new approaches to the management of enteric infections.

Pharmacotherapy, vaccines and malaria advice for HIV-infected travellers

Since the introduction of effective antiretroviral therapy (ART), HIV-infected individuals are travelling more frequently and international travel has become much safer. Specific concerns include the safety of ART during travel, drug adherence and interaction considerations, and effects of immunosuppression. This review describes potentially important infections, vaccine effectiveness, safety and special approaches for their use, and HIV-related issues regarding predeparture counselling. With advanced immunosuppression (CD4+ T-cell count < 200/microl or < 14%), the immunogenicity of several vaccines is reduced, complications could occur after live attenuated vaccines and certain infections acquired during travel may be more frequent or severe. Challenges include the best options for malaria chemoprophylaxis, standby treatment and medical follow-up of the increasing number of HIV-infected long-term travellers.

Posttreatment changes in Escherichia coli antimicrobial susceptibility rates among diarrheic patients treated with ciprofloxacin

Changes in antimicrobial resistance of Escherichia coli among deployed U.S. military personnel being treated for diarrhea were evaluated. Stool samples were collected pretreatment and on days 7, 14, and 28 posttreatment. Resistance to ciprofloxacin was noted in 13.3% of baseline specimens, and rates of resistance against multiple antibiotics increased dramatically from baseline to day 7 and then tapered off to return to pretreatment levels by day 28, except for ciprofloxacin, suggesting that population accumulative usage of fluoroquinolones may result in an incremental increase in resistance rates.

Traveller's diarrhoea

Traveller's diarrhoea affects over 50% of travellers to some destinations and can disrupt holidays and business trips. This review examines the main causes and epidemiology of the syndrome, which is associated with poor public health infrastructure and hygiene practices, particularly in warmer climates. Although travellers may be given common sense advice on avoidance of high-risk foods and other measures to prevent traveller's diarrhoea, adherence to such advice is sometimes difficult and the evidence for its effectiveness is contradictory. However, non-antimicrobial means for prevention of traveller's diarrhoea are favoured in most settings. A simple stepwise approach to the management of traveller's diarrhoea includes single doses or 3-day courses of antimicrobials, often self administered. The antibiotics of choice are currently fluoroquinolones or azithromycin, with an emerging role for rifaximin. In the long term, there will be greater benefit and effect on the health of local inhabitants and travellers from improving public health and hygiene standards at tourist destinations.

Travel-associated non-typhoidal salmonellosis: geographical and seasonal differences and serotype distribution

The Swedish database on notifiable communicable diseases was used to identify 24 803 cases of travel-associated non-typhoidal salmonellosis from the period 1997-2003. Serotype data were available for 24 358 (98.2%) of these cases, which were compared with a data set from the same period of 16 255 randomly selected Swedish residents with a history of recent overnight travel outside Sweden. The highest risk of disease was seen in travellers returning from East Africa (471/100 000 travellers; 95% CI 294-755), or the Indian subcontinent (474/100 000; 95% CI 330-681). Children aged 0-6 years were at higher risk than travellers of other ages (OR 2.4; 95% CI 2.1-2.8). Some distinct seasonal patterns could be distinguished, with highest (adjusted) risk in December in East Asia, and in August in Europe. Marked geographical differences in serotype distribution were noted. Salmonella Enteritidis was especially dominant in Europe, but was much less common in Africa, Asia and America, where the variety of circulating serotypes was greater. Overall, the two data sets provided important information on travel risks which are also likely to apply to travellers from other western countries.

The epidemiology of self-reported diarrhea in operations Iraqi freedom and enduring freedom

Diarrhea remains a potential cause of compromised military effectiveness. To assess diarrhea rates and mission impact in operations in Iraq and Afghanistan, a survey was administered to soldiers participating in the "Rest and Recuperation" program in Doha, Qatar. Between October and December 2003, 2,389 volunteers completed a questionnaire designed to assess the occurrence and impact of diarrhea. The median length of deployment was 7.2 months, 70% reported at least one episode, and 56% had multiple episodes of diarrhea. Overall, 43% reported decreased job performance for a median of 2 days, and 17% reported being on bed rest for a median of 2 days. While this survey showed high rates of diarrhea associated with decreased operational effectiveness, the results are consistent with prior military operations in this region. Further research is needed to develop better methods for illness prevention and its minimization on operational impact.

Antimicrobial Resistance Among Gram-Negative Foodborne Bacterial Pathogens Associated with Foods of Animal Origin

Antimicrobial-resistant foodborne pathogens are acquired primarily through consumption of contaminated food of animal origin or water. While there is much disagreement on the health burden imposed by resistance in foodborne bacterial pathogens, it is generally agreed that the use of antimicrobials, whether for growth promotion, prevention, or treatment, can select for resistant bacterial pathogens, and that these pathogens can be transmitted on food originating from sites processing treated animals. Information on the evolution and dissemination of antimicrobial resistance in foodborne pathogens shows that the situation is complex and differs by organism and antimicrobial. A clearer understanding of the ecology of resistance is needed in order to support science-based assessments of the public health risks due to the use of antimicrobials in the animal husbandry environment.

Public health consequences of macrolide use in food animals: a deterministic risk assessment

The potential impact on human health from antibiotic-resistant bacteria selected by use of antibiotics in food animals has resulted in many reports and recommended actions. The U.S. Food and Drug Administration Center for Veterinary Medicine has issued Guidance Document 152, which advises veterinary drug sponsors of one potential process for conducting a qualitative risk assessment of drug use in food animals. Using this guideline, we developed a deterministic model to assess the risk from two macrolide antibiotics, tylosin and tilmicosin. The scope of modeling included all label claim uses of both macrolides in poultry, swine, and beef cattle. The Guidance Document was followed to define the hazard, which is illness (i) caused by foodborne bacteria with a resistance determinant, (ii) attributed to a specified animal-derived meat commodity, and (iii) treated with a human use drug of the same class. Risk was defined as the probability of this hazard combined with the consequence of treatment failure due to resistant Campylobacter spp. or Enterococcus faecium. A binomial event model was applied to estimate the annual risk for the U.S. general population. Parameters were derived from industry drug use surveys, scientific literature, medical guidelines, and government documents. This unique farm-to-patient risk assessment demonstrated that use of tylosin and tilmicosin in food animals presents a very low risk of human treatment failure, with an approximate annual probability of less than 1 in 10 million Campylobacter-derived and approximately 1 in 3 billion E. faecium-derived risk.

Azithromycin Found to Be Comparable to Levofloxacin for the Treatment of US Travelers with Acute Diarrhea Acquired in Mexico

Increased drug resistance among enteropathogens is an emergent problem in travelers' diarrhea. This randomized, double-blind trial was conducted in Guadalajara, Mexico, during the summers of 1999-2001 to compare azithromycin with levofloxacin for the treatment of travelers' diarrhea. A total of 217 US adults were randomized to receive a single oral dose of azithromycin (1000 mg; 108 persons) or levofloxacin (500 mg; 109 persons), with a follow-up period of 4 days. Three patients in each group dropped out of the study. The median time between initiation of therapy and passage of the last unformed stool (azithromycin group, 22.3 h; levofloxacin group, 21.5 h) and the number of unformed stools passed during the 4-day follow-up period (azithromycin group, 6.5; levofloxacin group, 5.5) were similar. Treatment failure occurred in 10 patients (9.5%) receiving azithromycin and 8 patients (7.5%) receiving levofloxacin. Possible minor, self-limiting adverse events occurred in 57 patients in each treatment group. Azithromycin was found to be a safe and effective alternative to levofloxacin for the treatment of acute travelers' diarrhea in US adult travelers to Mexico.

Preparing the traveller

The four steps for giving travellers the foundation for healthy journeys are to assess their health, analyse their itineraries, select vaccines, and provide education about prevention and self-treatment of travel-related diseases. This process takes time. Since there is a risk of information overload, travellers should leave the clinic with some written advice for reinforcement. The order of these steps can be tailored to what best suits the travel clinic, but vaccinating early in the process allows monitoring for adverse reactions. Face-to-face discussion is vital for explaining the use and side-effects of medications. Those who provide a travel medicine service should be seeing many travellers and should seek specialist training. In 2003, the International Society of Travel Medicine introduced a certificate of knowledge examination in travel medicine. We cannot make travellers bullet-proof but it is possible to make them bullet-resistant. The pre-travel visit should minimise health risks specific to the journey, give travellers the capability to handle most minor medical problems, and allow them to identify when to seek local care during the trip or on return.

Antimicrobial susceptibilities of Campylobacter strains isolated from Finnish subjects infected domestically or from those infected abroad

The in vitro susceptibilities of 678 Campylobacter jejuni and Campylobacter coli strains isolated from stool samples of the same number of Finnish subjects were studied. A total of 523 patients, representing inhabitants from throughout Finland, had not traveled abroad within the 2 weeks prior to becoming ill, whereas 155 persons had presumably acquired their infections abroad. The antimicrobial agents studied were erythromycin, ciprofloxacin, levofloxacin, trovafloxacin, and moxifloxacin. The MICs of these antimicrobial agents were determined by the agar dilution method. The growth of all domestic isolates was inhibited by erythromycin at concentrations of 4 microg/ml, and for these isolates the fluoroquinolone MICs at which 90% of isolates are inhibited (MIC(90)s) ranged from 0.06 to 0.5 microg/ml. For the foreign isolates, the erythromycin MIC(90) was still low (4 microg/ml), but their susceptibilities to fluoroquinolones were clearly reduced (MIC(90)s, 8 to 64 microg/ml). Of the four different fluoroquinolones studied, ciprofloxacin was the least active (MIC(90), 64 micro g/ml).

Increasing fluoroquinolone resistance in Campylobacter jejuni, Pennsylvania, USA,1982-2001

Fluoroquinolone-resistant Campylobacter jejuni has been observed worldwide and is now being seen in the United States. Among patients in our health-care system in Pennsylvania, fluoroquinolone-resistant C. jejuni were not observed from 1982 to 1992; however, resistance increased to 40.5% in 2001. Resistance to erythromycin remains at a low level (<5%).

The place of probiotics in human intestinal infections

A number of studies have been carried out on the effect of several probiotic species on treatment and prevention of intestinal infections. The most commonly used microorganisms are lactic-acid producing bacteria such as lactobacilli and bifidobacteria belonging to the human normal microflora. In vitro and animal studies have shown that probiotic microorganisms interfere with the colonisation of Helicobacter pylori and of enteropathogenic microorganisms. In humans the significance is more uncertain. Clinically significant benefits of probiotics have been demonstrated in the treatment of rotavirus induced diarrhoea and of Saccharomyces boulardii in the prevention of antibiotic-associated diarrhoea (AAD). In patients suffering from inflammatory bowel disease, several probiotic strains have been shown to be as effective as traditional medication in preventing relapses. Standardised and well performed studies are needed to elucidate further the mechanisms of action and the clinical significance of probiotics.

Enterotoxigenic Escherichia coli as cause of diarrhea among Mexican adults and US travelers in Mexico

BACKGROUND

Enterotoxigenic Escherichia coli (ETEC) is the most common pathogen identified in travelers to Mexico with diarrhea. There have been few recent studies looking at the etiology of diarrhea in travelers compared with the local resident population.

METHODS

We compared enteric pathogens isolated in two populations experiencing acute diarrhea acquired in Guadalajara, Mexico and also compared clinical illness caused by the principal pathogen, ETEC.

RESULTS

A single and 2 enteropathogens were detected in 107 (23%) and 8 (2%), respectively, of 457 Mexicans in 1995 and 1997, and 37 (29%) and 2 (2%), respectively, of 127 US adults in 1997. The most common pathogen was ETEC in both groups (11% of Mexican, 19% of US adults), although more common in the US travelers group (p =.0017). Shigella spp and Cryptosporidium spp were less common in the Mexican (<1% and <1%, respectively) than in the travelers group (6% and 3%, respectively) (p <.001 and p =.002, respectively). Entamoeba histolytica was more often found in the Mexican group (4% Mexican, 0% US adults; p =.027).

CONCLUSION

ETEC is the most common pathogen among travelers and Mexican residents in this study. The duration of untreated diarrhea due to ETEC was significantly shorter among Mexicans (49 hours in Mexican, 94 hours in US adults; p =.0004), as was the average number of unformed stools passed over 4 days (Mexicans 8.8 versus travelers 17.9 stools; p =.0009

Recent Advances and New Challenges in Travel Medicine

Recent advances in travel medicine include the use of computer resources to obtain information on outbreaks and recommendations to travelers, the introduction of atovaquone/proguanil as chemoprophylaxis and treatment for malaria, the use of azithromycin as an alternative in the self-treatment of traveler's diarrhea, and the combination of hepatitis A and hepatitis B vaccines. At the same time, new challenges continue to appear. Shifts in the distribution of infections, such as West Nile virus and dengue fever, underscore the need for up-to-date information. Well-known infectious diseases, such as polio, meningococcal meningitis, and influenza are appearing in unexpected ways and settings. It is increasingly clear that travelers, while at risk for infections, also play a role in the global dispersal of pathogens, such as certain serogroups of Neisseria meningitidis and influenza. Increasing drug resistance affects the choice of drugs for treatment and chemoprophylaxis, and decisions about use of vaccines. Newly identified adverse events associated with yellow fever vaccine have prompted enhanced surveillance after vaccination and careful scrutiny of appropriate indications for the vaccine.

Update on Traveler's Diarrhea

Diarrhea is one of the most common health problems among travelers. Although enterotoxigenic Escherichia coli is implicated most commonly, enteroaggregative E. coli has recently been described as a major pathogen. Shigella, Campylobacter, and Salmonella organisms are less common causes of acute diarrhea, and intestinal protozoa are typical causes of protracted diarrhea. Although education is the mainstay of prevention measures, behavior modification has been shown to be difficult. Chemoprevention is rarely required with the availability of effective treatment, but there has been some interest in the use of vaccines. Maintenance of hydration is most important in children. In addition to bismuth preparations and loperamide, newer agents being developed for symptomatic relief include zaldaride maleate and racecadotril. Fluoroquinolones effectively treat severe traveler's diarrhea, and even a single dose may be sufficient. However, with the emergence of resistance, particularly in Campylobacter infection, other agents are required; interest has focused on azithromycin and rifaximin.

Tropical diarrhoea: new developments in traveller's diarrhoea

Traveller's diarrhoea is the most common illness acquired by visitors to developing countries, affecting 20-50% of the 35 million people who travel from industrialized countries each year. Important risk factors include point of origin and destination of the traveller, host factors, and exposure to contaminated food and water. The most common causes of traveller's diarrhoea in adults in developing countries include infection with Escherichia coli, Shigella spp., Salmonella spp., Campylobacter spp., Vibrio parahaemolyticus (in Asia), rotavirus (in Latin America), and protozoa (Giardia, Cryptosporidium and Cyclospora spp., and Entamoeba histolytica). No pathogen is identified in over half of patients with traveller's diarrhoea, however. The primary objectives of treatment of traveller's diarrhoea are to reduce the symptoms and duration of diarrhoeal illness, to reduce inconvenience caused by such illness and to prevent cancellation of planned activities. These important objectives are best accomplished by empirical self-therapy with a combination of antimicrobial agents and loperamide. Since the first use of ciprofloxacin, fluoroquinolones have become the drugs of choice in empirical therapy for moderate-to-severe traveller's diarrhoea in adults. The options for children include nalidixic acid, trimethoprim-sulfamethoxazole (along with erythromycin if Campylobacter infection is a possibility) and furazolidone. Education on hygiene and safe food preparation help to prevent many diarrhoeal diseases, including traveller's diarrhoea.

Diarrhea in the returned traveler

Diarrhea in the returned traveler is a common problem that can be caused by a number of different pathogens. A history of the patient's travel and exposures, the duration of illness, the response to prior treatment, and the clinical syndrome can help to establish a good etiologic differential diagnosis on which further therapy can be based. Many of these patients can be treated empirically with antibiotics, either a fluoroquinolone or azithromycin, without further microbiologic evaluation. Those patients with severe or persistent disease or comorbid illnesses, or those who have failed empiric therapy, should undergo further microbiologic evaluation with directed stool cultures and ova and parasite screening. For those patients with negative evaluations, further empiric therapy may be warranted if syndromes are suggestive of specific agents of infection, such as by Giardia or Cyclospora species. Other patients may require endoscopic evaluation to exclude diagnoses such as tropical sprue or inflammatory bowel disease.