Multiplex PCR testing for travelers’ diarrhea—friend or foe?

[Usefulness of Stool Multiplex Polymerase Chain Reaction Assays in Patients with Acute Diarrhea]

Background/Aims

There is a recent increase in the use of stool multiplex PCR assay-based diagnostic tests in patients with acute diarrhea. We used multiplex PCR assays to analyze the distribution of diarrhea-causing bacteria and viruses, as well as the clinical features of patients with acute diarrhea.

Methods

We retrospectively reviewed stool specimens of inpatients complaining of acute diarrhea from October 2018 to July 2020. The stool specimens had been tested for bacteria and viruses using multiplex PCR assays.

Results

A total of 414 stool specimens from 346 patients were tested, and 152 pathogens were detected in 131 stool samples (131/414, 31.6%). Co-infection was detected in 20 patients (20/346, 5.8%). The common pathogens detected as causes of acute diarrhea, including co-infection, were Clostridium perfringens (34.9%), Clostridioides difficile (19.7%), and Campylobacter spp. (18.4%). The average age of patients with multiplex PCR-positive tests was lower than those with multiplex PCR-negative tests (p=0.001). In patients with suspected C. difficile infection (CDI), the RT-PCR for toxin gene assay was performed in 370 stool samples, 35 of which were positive (9.5%). Furthermore, 16 of the 35 samples were positive on the multiplex PCR assay (45.7%).

Conclusions

The multiplex PCR assay revealed that C. perfringens was the most common diarrhea-causing pathogen. In addition, in patients with suspected CDI, the multiplex PCR assay alone was insufficiently sensitive to detect pathogens and a conventional CDI test was additionally required.

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.

Risk factors for different intestinal pathogens among patients with traveler's diarrhea: A retrospective analysis at a German travel clinic (2009-2017)

BACKGROUND

Travelers' diarrhea (TD) is the most common illness experienced by travelers to developing regions of the world and may be caused by bacterial, parasitic or viral pathogens. The available diagnostic tests include stool microscopy for parasitic infections, culture-dependent methods for bacterial infections and molecular methods for bacterial, parasitic and viral infections.

METHOD

We retrospectively evaluated demographic, clinical and microbiological data of patients presenting with TD at our travel clinic between 2009 and 2017.

RESULTS

Among 676 patients with TD included in our study, at least one etiologic agent was found in 21% (n = 145) of cases. In total, 195 enteropathogens were detected of which 110 were bacteria, 70 protozoa and 15 helminths. Bacterial infections were significantly more common when symptoms were present less than 14 days and travel duration did not exceed 29 days. Protozoa and helminths were predominantly detected in patients with longer lasting complaints. After stool culture was replaced by a multiplex-PCR gastrointestinal pathogen panel (GPP) at our center, significantly more intestinal bacterial pathogens were detected.

CONCLUSIONS

Our results support an individualized approach in the diagnostic workup of patients with TD taking host and travel characteristics into account to avoid unnecessary diagnostic testing. Molecular culture-independent diagnostic stool tests provide better coverage of the variety of etiological agents than traditional stool culture and have the benefit of rapid detection. However, the high sensitivity bears challenges differentiating colonization from infection.

Evaluation of the sick returned traveler

Infections are common during travel, and frontline physicians frequently must evaluate sick returned travelers. Sick travelers can be clinically challenging due to the wide range of endemic diseases in different geographic regions. To guide the diagnostic and treatment plan, consideration of endemic and emerging infections in the region of travel, as well as careful review of the travelers' exposures and preventative measures are necessary. Routine laboratory tests and cultures cannot confirm many tropical infections, and pathogen directed testing is typically required. Common tropical infections that can be severe, such as malaria, dengue, and enteric fever, should always be considered in the diagnostic evaluation. Providers should also be vigilant for rare but highly pathogenic emerging infections such as Ebola virus disease and Middle East respiratory syndrome (MERS).

Travelers' Diarrhea: A Clinical Review

BACKGROUND

Travelers' diarrhea is the most common travel-related malady. It affects millions of international travelers to developing countries annually and can significantly disrupt travel plans.

OBJECTIVE

To provide an update on the evaluation, diagnosis, treatment, and prevention of traveler's diarrhea.

METHODS

A PubMed search was completed in Clinical Queries using the key term "traveler's diarrhea". The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews. The search was restricted to English literature. Patents were searched using the key term "traveler's diarrhea" from www.freepatentsonline.com.

RESULTS

Between 10% and 40% of travelers develop diarrhea. The attack rate is highest for travelers from a developed country who visit a developing country. Children are at particular risk. Travelers' diarrhea is usually acquired through ingestion of food and water contaminated by feces. Most cases are due to a bacterial pathogen, commonly, Escherichia coli, and occur within the first few days after arrival in a foreign country. Dehydration is the most common complication. Pretravel education on hygiene and on the safe selection of food items is important in minimizing episodes. For mild travelers' diarrhea, the use of antibiotic is not recommended. The use of bismuth subsalicylate or loperamide may be considered. For moderate travelers' diarrhea, antibiotics such as fluoroquinolones, azithromycin, and rifaximin may be used. Loperamide may be considered as monotherapy or adjunctive therapy. For severe travelers' diarrhea, antibiotics such as azithromycin, fluoroquinolones, and rifaximin should be used. Azithromycin can be used even for the treatment of dysentery whereas fluoroquinolones and rifaximin cannot be used for such purpose. Recent patents related to the management of travelers' diarrhea are discussed.

CONCLUSION

Although travelers' diarrhea is usually self-limited, many travelers prefer expedient relief of diarrhea, especially when they are traveling for extended periods by air or ground. Judicious use of an antimotility agent and antimicrobial therapy reduces the duration and severity of diarrhea.

Antibiotic resistance in travellers' diarrhoeal disease, an external perspective

BACKGROUND

There are many recommendations on the use of antibiotics for prophylaxis and treatment of travellers' diarrhoea (TD). As pharmacists with a special interest in antimicrobial stewardship, we examine and offer our perspective on advice that is recommended to travellers in terms of prevention, treatment and management of TD with a focus on antibiotic use and resistance.

METHODS

Publications on TD were identified through PubMed, Google Scholar and Cochrane Library databases searches using search terms 'travellers diarrhoea', 'travellers diarrhoea', 'travellers' diarrhoea' 'guidelines', 'expert opinion', 'expert reviews', 'South Asia' and 'South East Asia' (S and SE Asia), 'antibiotics', 'resistance genes', 'travel advice', 'pharmacists', 'guidelines', 'prevention' and 'treatment'. References of articles were also screened for additional relevant studies.

RESULTS

Whilst most guidelines and expert reviews were in agreement with the restricted use of antibiotics unless there was a clinical need, the literature review identified gaps in research into behaviours of travellers regarding non-compliance with the pre-travel advice provided and the need for in depth training and education for all healthcare professionals in providing 'tailored' advice for travellers going to high-risk destinations.

CONCLUSIONS

Travellers should be made aware of the problems of antimicrobial resistance in their destination and home countries and offered alternative forms of prophylaxis for TD. Strategies for prevention of TD, other than the use of antibiotics, also need to be emphasized. All healthcare professionals involved in giving advice about TD should be familiar with the epidemiology of the condition as this will inform responsible behaviours, risk assessment and management strategies in different geographical areas.