Acquisition of Antibiotic-Resistant Bacteria by U.S. International Travelers

Alterations in faecal microbiome and resistome in Chinese international travellers: a metagenomic analysis

BACKGROUND

International travel increases the risk of acquisition of antibiotic-resistant bacteria and antibiotic resistance genes (ARGs). Previous studies have characterized the changes in the gut microbiome and resistome of Western travellers; however, information on non-Western populations and the effects of travel-related risk factors on the gut microbiome and resistome remains limited.

METHODS

We conducted a prospective observational study on a cohort of 90 healthy Chinese adult residents of Hong Kong. We characterized the microbiome and resistome in stools collected from the subjects before and after travelling to diverse international locations using shotgun metagenomic sequencing and examined their associations with travel-related variables.

RESULTS

Our results showed that travel neither significantly changed the taxonomic composition of the faecal microbiota nor altered the alpha (Shannon) or beta diversity of the faecal microbiome or resistome. However, travel significantly increased the number of ARGs. Ten ARGs, including aadA, TEM, mgrB, mphA, qnrS9 and tetR, were significantly enriched in relative abundance after travel, eight of which were detected in metagenomic bins belonging to Escherichia/Shigella flexneri in the post-trip samples. In sum, 30 ARGs significantly increased in prevalence after travel, with the largest changes observed in tetD and a few qnrS variants (qnrS9, qnrS and qnrS8). We found that travel to low- or middle-income countries, or Africa or Southeast Asia, increased the number of ARG subtypes, whereas travel to low- or middle-income countries and the use of alcohol-based hand sanitizer (ABHS) or doxycycline as antimalarial prophylaxis during travel resulted in increased changes in the beta diversity of the faecal resistome.

CONCLUSIONS

Our study highlights travel to low- or middle-income countries, Africa or Southeast Asia, a long travel duration, or the use of ABHS or doxycycline as antimalarial prophylaxis as important risk factors for the acquisition/enrichment of ARGs during international travel.

Development of a prediction model for the acquisition of extended spectrum beta-lactam-resistant organisms in U.S. international travellers

BACKGROUND

Extended spectrum beta-lactamase producing Enterobacterales (ESBL-PE) present a risk to public health by limiting the efficacy of multiple classes of beta-lactam antibiotics against infection. International travellers may acquire these organisms and identifying individuals at high risk of acquisition could help inform clinical treatment or prevention strategies.

METHODS

We used data collected from a cohort of 528 international travellers enrolled in a multicentre US-based study to derive a clinical prediction rule (CPR) to identify travellers who developed ESBL-PE colonization, defined as those with new ESBL positivity in stool upon return to the United States. To select candidate features, we used data collected from pre-travel and post-travel questionnaires, alongside destination-specific data from external sources. We utilized LASSO regression for feature selection, followed by random forest or logistic regression modelling, to derive a CPR for ESBL acquisition.

RESULTS

A CPR using machine learning and logistic regression on 10 features has an internally cross-validated area under the receiver operating characteristic curve (cvAUC) of 0.70 (95% confidence interval 0.69-0.71). We also demonstrate that a four-feature model performs similarly to the 10-feature model, with a cvAUC of 0.68 (95% confidence interval 0.67-0.69). This model uses traveller's diarrhoea, and antibiotics as treatment, destination country waste management rankings and destination regional probabilities as predictors.

CONCLUSIONS

We demonstrate that by integrating traveller characteristics with destination-specific data, we could derive a CPR to identify those at highest risk of acquiring ESBL-PE during international travel.

Travel Medicine

International travel can cause new illness or exacerbate existing conditions. Because primary care providers are frequent sources of health advice to travelers, they should be familiar with destination-specific disease risks, be knowledgeable about travel and routine vaccines, be prepared to prescribe chemoprophylaxis and self-treatment regimens, and be aware of travel medicine resources. Primary care providers should recognize travelers who would benefit from referral to a specialized travel clinic for evaluation. Those requiring yellow fever vaccination, immunocompromised hosts, pregnant persons, persons with multiple comorbid conditions, or travelers with complex itineraries may warrant specialty referral.

Antimicrobial-Resistant Nontyphoidal Salmonella Infection Following International Travel-United States, 2018-2019

BACKGROUND

Antimicrobial resistance in nontyphoidal Salmonella (NTS) can limit treatment options. We assessed the contribution of international travel to antimicrobial-resistant NTS infections.

METHODS

We describe NTS infections that were reported to the Foodborne Diseases Active Surveillance Network during 2018-2019 and screened for genetic resistance determinants, including those conferring decreased susceptibility to first-line agents (ciprofloxacin, ceftriaxone, or azithromycin). We used multivariable logistic regression to assess the association between resistance and international travel during the 7 days before illness began. We estimated the contribution of international travel to resistance using population-attributable fractions, and we examined reported antimicrobial use.

RESULTS

Among 9301 NTS infections, 1159 (12%) occurred after recent international travel. Predicted resistance to first-line antimicrobials was more likely following travel; the adjusted odds ratio varied by travel region and was highest after travel to Asia (adjusted odds ratio, 7.2 [95% confidence interval, 5.5-9.5]). Overall, 19% (95% confidence interval, 17%-22%) of predicted resistance to first-line antimicrobials was attributable to international travel. More travelers than nontravelers receiving ciprofloxacin or other fluoroquinolones had isolates with predicted resistance to fluoroquinolones (29% vs 9%, respectively; P < .01).

CONCLUSIONS

International travel is a substantial risk factor for antimicrobial-resistant NTS infections. Understanding risks of resistant infection could help target prevention efforts.

Acquisition of Enterobacterales carrying the colistin resistance gene mcr following travel to the tropics

BACKGROUND

Colistin is an antibiotic of last resort in the management of highly drug-resistant Enterobacterales infections. Travel to some destinations presents a high risk of acquiring multidrug-resistant Enterobacterales, but little data are available on the risk of acquiring colistin-resistant strains. Here, we use the VOYAG-R sample collection (2012-2013) in order to evaluate the rate of acquisition of colistin-resistant Enterobacterales, excluding species with intrinsic resistance (CRE), following travel to tropical regions.

METHODS

A total of 574 frozen stool samples of travellers returning from tropical regions were screened for colistin-resistant strains using ChromID Colistin R agar (bioMerieux®) after pre-enrichment culture with 1 mg/L of colistin. Genomes were obtained by Illumina sequencing and genetic determinants of colistin resistance (mutational events and mcr genes) were searched.

RESULTS

A total of 22 travellers (3.8%) acquired colistin-resistant Enterobacterales carrying an mcr gene. Acquisition rates varied between visited regions: 9.2% (18/195) for Asia (southeast Asia: 17/18), 2.2% (4/184) for Latin America (Peru: 4/4) and 0% from Africa (0/195). Acquired strains were predominantly Escherichia coli (92%) and carried mostly the mcr-1 variant (83%). Escherichia coli strains belonged mainly to commensal phylogroups A and B1, and were genetically highly diverse (5 non-clonal sequence type (ST)10 and 17 ST singletons). Only four non mcr colistin-resistant strains (two E. coli and two Enterobacter cloacae complex) were identified. Among all the strains, two also carried extended-spectrum beta-lactamase genes.

CONCLUSIONS

Travel to tropical regions, and particularly to Southeast Asia, is a risk factor for the acquisition of mcr-carrying Enterobacterales. This study highlights the community dissemination of mcr in humans as early as 2012, 4 years prior to its first published description.

Colonization with extended-spectrum beta-lactamase-producing Escherichia coli and traveler's diarrhea attack rates among travelers to India: a systematic review and meta-analysis

Background

India is an attractive destination for travelers. Unfortunately, numerous reports exist on traveler’s diarrhea (TD) and fecal colonization with extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) among international travelers visiting India. Here, we systematically reviewed studies published on the acquisition of ESBL-EC and TD attack rates among international visitors to India.

Methods

Design: Systematic review and meta-analysis.

A systematic search was performed using Google Scholar, PubMed, EMBASE, Web of Science, and gray literature from 2000 to December 2021, for studies containing data for ESBL-EC acquisition or TD experience related to a trip to India. Random effects models were used to compute the prevalence of ESBL-EC acquisition and TD attack.

Results

The literature search yielded a total of 5023 records. Of these, 31 met our inclusion criteria for systematic review and only 17 could be meta-analyzed (9 for TD, and 8 for ESBL-EC). The overall pooled attack rate of TD was 39% (95% confidence interval, CI: 25–53%). In studies where travelers' memory was used to diagnose TD, the pooled attack rate of TD was slightly higher (42%, 95% CI: 21–64%) compared to those where TD was objectively documented (33%, 95% CI: 17–49%). There were significant risks to be colonized with ESBL-EC among the travelers who experienced TD. The pooled rate of ESBL-EC colonization was 72% (CI: 67–78%). Most ESBL-EC produced CTX-M-15 enzyme. Furthermore, most of the travelers who acquired ESBL-EC were from highly industrialized countries recruited from travel clinics: Canada (n = 80), Germany (n = 69), Netherlands (n = 20), Sweden (n = 18), Japan (n = 10), Finland (n = 8), USA (n = 7), Spain (n = 5), and Denmark (n = 3).

Conclusions

TD pooled attack rate and ESBL-EC acquisition among international travelers visiting India were high in this study. However, we cannot make generalizations based upon this TD pooled attack rate for the current situation, due to a lack of current data. Our study highlights that travelers should be advised on TD to ensure that they do not disregard the risk of contracting TD and be better prepared as a result. It also illustrates the importance of international travel in acquiring antibiotic-resistant Escherichia coli.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40794-022-00179-1.

International Travel as a Risk Factor for Carriage of Extended-Spectrum β-Lactamase-Producing Escherichia coli in a Large Sample of European Individuals—The AWARE Study

Antibiotic resistance (AR) is currently a major threat to global health, calling for a One Health approach to be properly understood, monitored, tackled, and managed. Potential risk factors for AR are often studied in specific high-risk populations, but are still poorly understood in the general population. Our aim was to explore, describe, and characterize potential risk factors for carriage of Extended-Spectrum Beta-Lactamase-resistant Escherichia coli (ESBL-EC) in a large sample of European individuals aged between 16 and 67 years recruited from the general population in Southern Germany, the Netherlands, and Romania. Questionnaire and stool sample collection for this cross-sectional study took place from September 2018 to March 2020. Selected cultures of participants’ stool samples were analyzed for detection of ESBL-EC. A total of 1183 participants were included in the analyses: 333 from Germany, 689 from the Netherlands, and 161 from Romania. Travels to Northern Africa (adjusted Odds Ratio, aOR 4.03, 95% Confidence Interval, CI 1.67–9.68), Sub-Saharan Africa (aOR 4.60, 95% CI 1.60–13.26), and Asia (aOR 4.08, 95% CI 1.97–8.43) were identified as independent risk factors for carriage of ESBL-EC. Therefore, travel to these regions should continue to be routinely asked about by clinical practitioners as possible risk factors when considering antibiotic therapy.

Antimicrobial-resistant bacteria in international travelers

PURPOSE OF REVIEW

Antimicrobial resistance (AMR) in bacteria poses a major risk to global public health, with many factors contributing to the observed increase in AMR. International travel is one recognized contributor. The purpose of this review is to summarize current knowledge regarding the acquisition, carriage and spread of AMR bacteria by international travelers.

RECENT FINDINGS

Recent studies have highlighted that travel is an important risk factor for the acquisition of AMR bacteria, with approximately 30% of studied travelers returning with an acquired AMR bacterium. Epidemiological studies have shown there are three major risk factors for acquisition: travel destination, antimicrobial usage and travelers' diarrhea (TD). Analyses have begun to illustrate the AMR genes that are acquired and spread by travelers, risk factors for acquisition and carriage of AMR bacteria, and local transmission of imported AMR organisms.

SUMMARY

International travel is a contributor to the acquisition and dissemination of AMR organisms globally. Efforts to reduce the burden of AMR organisms should include a focus on international travelers. Routine genomic surveillance would further elucidate the role of international travel in the global spread of AMR bacteria.

Polymyxin resistance in Enterobacterales: overview and epidemiology in the Americas

The worldwide spread of carbapenem- and polymyxin-resistant Enterobacterales represents an urgent public-health threat. However, for most countries in the Americas, the available data are limited, although Latin America has been suggested as a silent spreading reservoir for isolates carrying plasmid-mediated polymyxin resistance mechanisms. This work provides an overall update on polymyxin and polymyxin resistance and focuses on uses, availability and susceptibility testing. Moreover, a comprehensive review of the current polymyxin resistance epidemiology in the Americas is provided. We found that reports in the English and Spanish literature show widespread carbapenemase-producing and colistin-resistant Klebsiella pneumoniae in the Americas determined by the clonal expansion of the pandemic clone ST258 and mgrB-mediated colistin resistance. In addition, widespread IncI2 and IncX4 plasmids carrying mcr-1 in Escherichia coli come mainly from human sources; however, plasmid-mediated colistin resistance in the Americas is underreported in the veterinary sector. These findings demonstrate the urgent need for the implementation of polymyxin resistance surveillance in Enterobacterales as well as appropriate regulatory measures for antimicrobial use in veterinary medicine.

Multiresistant Gram-Negative Pathogens—A Zoonotic Problem

BACKGROUND

Extended-spectrum-β-lactamase-producing, carbapenemase-producing, and colistin-resistant Enterobacteriaceae (ESBL-E, CPE, and Col-E) are multiresistant pathogens that are increasingly being encountered in both human and veterinary medicine. In this review, we discuss the frequency, sources, and significance of the zoonotic transmission of these pathogens between animals and human beings.

METHODS

This review is based on pertinent publications retrieved by a selective literature search. Findings for Germany are presented in the global context.

RESULTS

ESBL-E are common in Germany in both animals and human beings, with a 6-10% colonization rate in the general human population. A major source of ESBL-E is human-tohuman transmission, partly through travel. Some colonizations are of zoonotic origin (i.e., brought about by contact with animals or animal-derived food products); in the Netherlands, more than 20% of cases are thought to be of this type. CPE infections, on the other hand, are rare in Germany in both animals and human beings. Their main source in human beings is nosocomial transmission. Col-E, which bear mcr resistance genes, have been described in Germany mainly in food-producing animals and their meat. No representative data are available on Col-E in human beings in Germany; in Europe, the prevalence of colonization is less than 2%, with long-distance travel as a risk factor. The relevance of animals as a source of Col-E for human beings is not yet entirely clear.

CONCLUSION

Livestock farming and animal contact affect human colonization with the multiresistant Gram-negative pathogens CPE, ESBL-E and Col-E to differing extents. Improved prevention will require the joint efforts of human and veterinary medicine.

Destination shapes antibiotic resistance gene acquisitions, abundance increases, and diversity changes in Dutch travelers

BACKGROUND

Antimicrobial-resistant bacteria and their antimicrobial resistance (AMR) genes can spread by hitchhiking in human guts. International travel can exacerbate this public health threat when travelers acquire AMR genes endemic to their destinations and bring them back to their home countries. Prior studies have demonstrated travel-related acquisition of specific opportunistic pathogens and AMR genes, but the extent and magnitude of travel's effects on the gut resistome remain largely unknown.

METHODS

Using whole metagenomic shotgun sequencing, functional metagenomics, and Dirichlet multinomial mixture models, we investigated the abundance, diversity, function, resistome architecture, and context of AMR genes in the fecal microbiomes of 190 Dutch individuals, before and after travel to diverse international locations.

RESULTS

Travel markedly increased the abundance and α-diversity of AMR genes in the travelers' gut resistome, and we determined that 56 unique AMR genes showed significant acquisition following international travel. These acquisition events were biased towards AMR genes with efflux, inactivation, and target replacement resistance mechanisms. Travel-induced shaping of the gut resistome had distinct correlations with geographical destination, so individuals returning to The Netherlands from the same destination country were more likely to have similar resistome features. Finally, we identified and detailed specific acquisition events of high-risk, mobile genetic element-associated AMR genes including qnr fluoroquinolone resistance genes, blaCTX-M family extended-spectrum β-lactamases, and the plasmid-borne mcr-1 colistin resistance gene.

CONCLUSIONS

Our results show that travel shapes the architecture of the human gut resistome and results in AMR gene acquisition against a variety of antimicrobial drug classes. These broad acquisitions highlight the putative risks that international travel poses to public health by gut resistome perturbation and the global spread of locally endemic AMR genes.

Acquisition of antimicrobial resistance determinants in Enterobacterales by international travelers from a large urban setting in Brazil

BACKGROUND

Antimicrobial resistance is increased by international mobility. We present data about intestinal colonization of travelers departing from a middle-income country.

METHODS

Travelers were recruited from 2015 to 2019, collected an anal stool specimen and answered a questionnaire before and after travel. Enterobacterales isolates were investigated for antimicrobial resistance; extended-spectrum beta-lactamase (ESBL) and carbapenemase production; plasmid-encoded cephalosporinases (pAmpC), plasmid-mediated quinolone resistance (PMQR) and mcr genes by PCR and sequencing; and association with travel related variables.

RESULTS

Among 210 travelers, 26 (12%) carried multidrug-resistant Enterobacterales (MDR-E) and 18 (9%) ESBL-producing Enterobacterales (ESBL-E) before travel, with an increased prevalence from 1% to 11% over the study years. Acquisition of MDR-E and ESBL-E occurred in 59 (32%) and 43 (22%) travelers, respectively, mostly bla_CTX-M-15 carrying Escherichia coli. One traveler acquired one isolate carrying bla_OXA-181 gene, and two others, isolates carrying mcr-1. PMQR were detected in 14 isolates of returning travelers. The risk of MDR-E acquisition was higher in Southeast Asia and the Indian subcontinent, and after using antimicrobial agents.

CONCLUSION

We describe an increasing pre-travel prevalence of ESBL-E colonization in subjects departing from this middle-income country over time. Travel to known risk areas and use of antimicrobial agents during travel were associated with acquisition of MDR-E. Travel advice is critical to mitigating this risk, as colonization by MDR-E may raise the chances of antimicrobial-resistant infections.

Potential of Therapeutic Bacteriophages in Nosocomial Infection Management

Nosocomial infections (NIs) are hospital-acquired infections which pose a high healthcare burden worldwide. The impact of NIs is further aggravated by the global spread of antimicrobial resistance (AMR). Conventional treatment and disinfection agents are often insufficient to catch up with the increasing AMR and tolerance of the pathogenic bacteria. This has resulted in a need for alternative approaches and raised new interest in therapeutic bacteriophages (phages). In contrast to the limited clinical options available against AMR bacteria, the extreme abundance and biodiversity of phages in nature provides an opportunity to establish an ever-expanding phage library that collectively provides sustained broad-spectrum and poly microbial coverage. Given the specificity of phage-host interactions, phage susceptibility testing can serve as a rapid and cost-effective method for bacterial subtyping. The library can also provide a database for routine monitoring of nosocomial infections as a prelude to preparing ready-to-use phages for patient treatment and environmental sterilization. Despite the remaining obstacles for clinical application of phages, the establishment of phage libraries, pre-stocked phage vials prepared to good manufacturing practice (GMP) standards, and pre-optimized phage screening technology will facilitate efforts to make phages available as modern medicine. This may provide the breakthrough needed to demonstrate the great potential in nosocomial infection management.

Social distancing to combat COVID-19 led to a marked decrease in food-borne infections and sexually transmitted diseases in Spain

Data from a recent epidemiological surveillance network showed a decrease in the reported number of sexually transmitted diseases (STDs) and food-borne infections. We reflect on the possible drivers and consequences of a decrease in these transmittable infectious diseases linked to human contact in relation to social distancing due to the COVID-19 pandemic in Madrid (Spain).

Acquisition and Long-term Carriage of Multidrug-Resistant Organisms in US International Travelers

We performed prospective screening of stool for multidrug-resistant organisms from 608 US international travelers and identified an acquisition rate of 38% following travel. Carriage rates remained significantly elevated for at least 6 months post-travel. Travel-related diarrhea was a risk factor for acquisition, as well as for long-term carriage upon return.

Acquisition of multidrug-resistant bacteria and colistin resistance genes in French medical students on internships abroad

BACKGROUND

Acquisition of multidrug resistant bacteria (MDR) and colistin resistance genes by international travellers has been demonstrated. Studies conducted in medical students during internships abroad are scant.

METHODS

Nasopharyngeal, rectal, and vaginal swabs samples were collected from 382 French medical students before and after travel to investigate the acquisition of MDR bacteria. The bacterial diversity in the samples was assessed by culture on selective media. We also genetically characterised the isolates of MDR bacteria including Extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E), methicillin-resistant Staphylococcus aureus (MRSA), and Carbapenemase-producing Enterobacteriacae (CPE) using the real-time polymerase chain reaction method. The samples were collected from 293 students and were investigated for mcr colistin-resistance genes using RT-PCR directly on the samples, followed by conventional PCR and sequencing.

RESULTS

A proportion of 29.3% (112/382) of the participants had acquired ESBL-E and 2.6% (10/382) had acquired CPE. The most common species and ESBL-E encoding gene were Escherichia coli (125/127 isolates, 98.4%) and bla_CTX-M-A (121/127, 95.3%), respectively. A proportion of 6.8% (20/293) of the participants had acquired mcr-1 genes, followed by mcr-3 (1/293, 0.3%) and mcr-8 (1/293, 0.3%). We found that taking part in humanitarian missions to orphanages (aRR = 2.01, p < 0.0001), being in contact with children during travel (aRR = 1.78, p = 0.006), the primary destination of travel being Vietnam (aRR = 2.15, p < 0.0001) and north India (aRR = 2.41, p = 0.001), using antibiotics during travel (aRR = 1.77, p = 0.01), and studying in 2018 (aRR = 1.55, p = 0.03) were associated with the acquisition of ESBL-E. When the primary destination of travel was Vietnam (aRR = 2.74, p < 0.0001) and the year of study was 2018 (aRR = 1.93, p < 0.002), this was associated with acquisition of colistin resistance genes.

CONCLUSION

Medical students are at a potential risk of acquiring ESBL-E, CPE and colistin resistance genes. A number of risk factors have been identified, which may be used to develop targeted preventive measures.

Prescribing Patterns of Antibiotics for the Self-Treatment of Travelers' Diarrhea in Global TravEpiNet, 2009-2018

Background

International travelers are often prescribed antibiotics for self-treatment of travelers' diarrhea (TD), but the benefits and risks of antibiotics are debated. We assessed the prescribing patterns of empiric antibiotics for TD in international travelers evaluated at Global TravEpiNet (GTEN) sites (2009-2018).

Methods

We performed a prospective, multisite cross-sectional study regarding antibiotic prescriptions for the self-treatment of TD at 31 GTEN sites providing pretravel consultations to adult international travelers. We described traveler demographics, itineraries, and antibiotic(s) prescribed. We used multivariable logistic regressions to assess the association of year of consultation with antibiotic prescribing (yes/no) and class (fluoroquinolones vs azithromycin). We performed interrupted time-series analyses to examine differences in prescribing before and after the Food and Drug Administration (FDA) warning on fluoroquinolones (July 2016).

Results

Antibiotics were not prescribed in 23 096 (22.2%) of 103 843 eligible pretravel GTEN consultations; azithromycin and fluoroquinolones were most frequently prescribed. Antibiotic prescribing declined significantly each year between 2009 and 2018 (odds ratio [OR], 0.84; 95% CI, 0.79-0.89), as did fluoroquinolone prescribing, relative to azithromycin (OR, 0.77; 95% CI, 0.73-0.82). The rate of decline in fluoroquinolone prescribing was significantly greater after the FDA fluoroquinolone warning (15.3%/year) than before (1.1%/year; P < .001).

Conclusions

Empiric antibiotics for TD were prescribed in >75% of pretravel GTEN consultations, but antibiotic prescribing declined steadily between 2009 and 2018. Fluoroquinolones were less frequently prescribed than azithromycin, especially after the 2016 FDA fluoroquinolone warning. Emphasis on the risks of antibiotics may influence antibiotic prescribing by providers for empiric treatment of TD.