Trends in antibiotic resistance among diarrheal pathogens isolated in Thailand over 15 years

New 1,3-diphenyl-1H-pyrazol-5-ols as anti-methicillin resistant Staphylococcus aureus agents: Synthesis, antimicrobial evaluation and in silico studies

In the present work, two hybrid series of pyrazole-clubbed pyrimidine and pyrazole-clubbed thiazole compounds 3-21 from 4-acetyl-1,3-diphenyl-1H-pyrazole-5(4H)-ole 1 were synthesized as novel antimicrobial agents. Their chemical structures were thoroughly elucidated in terms of spectral analyses such as IR, 1H NMR, 13C NMR and mass spectra. The compounds were in vitro evaluated for their antimicrobial efficiency against various standard pathogen strains, gram -ive bacteria (Pseudomonas aeruginosa, Klebsiella pneumonia), gram + ive bacteria (MRSA, Bacillus subtilis), and Unicellular fungi (Candida albicans) microorganisms. The ZOI results exhibited that most of the tested molecules exhibited inhibition potency from moderate to high. Where compounds 7, 8, 12, 13 and 19 represented the highest inhibition potency against most of the tested pathogenic microbes comparing with the standard drugs. In addition, the MIC results showed that the most potent molecules 7, 8, 12, 13 and 19 showed inhibition effect against most of the tested microbes at low concentration. Moreover, the docking approach of the newly synthesized compounds against DNA gyrase enzyme was performed to go deeper into their molecular mechanism of antimicrobial efficacy. Further, computational investigations to calculate the pharmacokinetics parameters of the compounds were performed. Among them 7, 8, 12, 13 and 19 are the most potent compounds revealed the highest inhibition efficacy against most of the tested pathogenic microbes comparing with the standard drugs.

The zoonotic pathogen Wohlfahrtiimonas chitiniclastica - current findings from a clinical and genomic perspective

The zoonotic pathogen Wohlfahrtiimonas chitiniclastica can cause several diseases in humans, including sepsis and bacteremia. Although the pathogenesis is not fully understood, the bacterium is thought to enter traumatic skin lesions via fly larvae, resulting in severe myiasis and/or wound contamination. Infections are typically associated with, but not limited to, infestation of an open wound by fly larvae, poor sanitary conditions, cardiovascular disease, substance abuse, and osteomyelitis. W. chitiniclastica is generally sensitive to a broad spectrum of antibiotics with the exception of fosfomycin. However, increasing drug resistance has been observed and its development should be monitored with caution. In this review, we summarize the currently available knowledge and evaluate it from both a clinical and a genomic perspective.

Antimicrobial resistance of enteric pathogens in the Military Health System, 2009 - 2019

BACKGROUND

Acute diarrhea (AD) can have significant impacts on military troop readiness. Medical providers must understand current trends of enteropathogen antimicrobial resistance (AMR) in service members (SMs) to inform proper, timely treatment options. However, little is known of enteric pathogen profiles across the Military Health System (MHS). The primary objectives of this study were to identify gaps in enteric pathogen surveillance within the MHS, describe the epidemiology of AMR in enteric pathogens, and identify trends across the MHS both within the Continental United States (CONUS) and outside of the Continental United States (OCONUS).

METHODS

Health Level 7 (HL7)-formatted laboratory data were queried for all specimens where Salmonella, Shigella, and Campylobacter species, as well as Shiga toxin-producing Escherichia coli (E. coli) (STEC) were isolated and certified between 1 January 2009 - 31 December 2019. Antibiotic susceptibility testing (AST) results were queried and summarized where available. Descriptive statistics were calculated for each organism by specimen source, year, and susceptibility testing availability.

RESULTS

Among a total of 13,852 enteric bacterial isolates, 11,877 (86%) were submitted from CONUS locations. Out of 1479 Shigella spp. and 6755 Salmonella spp. isolates, 1221 (83%) and 5019 (74%), respectively, reported any susceptibility results through the MHS. Overall, only 15% of STEC and 4% of Campylobacter spp. specimens had AST results available. Comparing AST reporting at CONUS versus OCONUS locations, AST was reported for 1175 (83%) and 46 (78%) of Shigella isolates at CONUS and OCONUS locations, respectively, and for 4591 (76%) and 428 (63%) of Salmonella isolates at CONUS and OCONUS locations, respectively.

CONCLUSIONS

This study revealed inconsistent enteropathogen AST conducted across the MHS, with differing trends between CONUS and OCONUS locations. Additional work is needed to assess pathogen-specific gaps in testing and reporting to develop optimal surveillance that supports the health of the force.

Mechanism of action, resistance, synergism, and clinical implications of azithromycin

Background

Azithromycin (AZM), sold under the name Zithromax, is classified as a macrolide. It has many benefits due to its immunomodulatory, anti‐inflammatory, and antibacterial effects. This review aims to study different clinical and biochemisterial aspects and properties of this drug which has a priority based on literature published worldwide.

Methods

Several databases including Web of Science, Google Scholar, PubMed, and Scopus were searched to obtain the relevant studies.

Results

AZM mechanism of action including the inhibition of bacterial protein synthesis, inhibition of proinflammatory cytokine production, inhibition of neutrophil infestation, and macrophage polarization alteration, gives it the ability to act against a wide range of microorganisms. Resistant organisms are spreading and being developed because of the irrational use of the drug in the case of dose and duration. AZM shows synergistic effects with other drugs against a variety of organisms. This macrolide is considered a valuable antimicrobial agent because of its use as a treatment for a vast range of diseases such as asthma, bronchiolitis, COPD, cystic fibrosis, enteric infections, STIs, and periodontal infections.

Conclusions

Our study shows an increasing global prevalence of AZM resistance. Thus, synergistic combinations are recommended to treat different pathogens. Moreover, continuous monitoring of AZM resistance by registry centers and the development of more rapid diagnostic assays are urgently needed.

Contribution of Governance and Socioeconomic Factors to the P. aeruginosa MDR in Europe

This work aims to explain the behavior of the multi-drug resistance (MDR) percentage of Pseudomonas aeruginosa in Europe, through multivariate statistical analysis and machine learning validation, using data from the European Antimicrobial Resistance Surveillance System, the World Health Organization, and the World Bank. We ran a multidimensional data panel regression analysis and used machine learning techniques to validate a pooling panel data case. The results of our analysis showed that the most important variables explaining the MDR phenomena across European countries are governance variables, such as corruption control and the rule of law. The models proposed in this study showed the complexity of the antibiotic drugs resistance problem. The efforts controlling MDR P. aeruginosa, as a well-known Healthcare-Associated Infection (HCAI), should be focused on solving national governance problems that impact resource distribution, in addition to individual guidelines, such as promoting the appropriate use of antibiotics.

Nanotechnology as a Novel Approach in Combating Microbes Providing an Alternative to Antibiotics

The emergence of infectious diseases promises to be one of the leading mortality factors in the healthcare sector. Although several drugs are available on the market, newly found microorganisms carrying multidrug resistance (MDR) against which existing drugs cannot function effectively, giving rise to escalated antibiotic dosage therapies and the need to develop novel drugs, which require time, money, and manpower. Thus, the exploitation of antimicrobials has led to the production of MDR bacteria, and their prevalence and growth are a major concern. Novel approaches to prevent antimicrobial drug resistance are in practice. Nanotechnology-based innovation provides physicians and patients the opportunity to overcome the crisis of drug resistance. Nanoparticles have promising potential in the healthcare sector. Recently, nanoparticles have been designed to address pathogenic microorganisms. A multitude of processes that can vary with various traits, including size, morphology, electrical charge, and surface coatings, allow researchers to develop novel composite antimicrobial substances for use in different applications performing antimicrobial activities. The antimicrobial activity of inorganic and carbon-based nanoparticles can be applied to various research, medical, and industrial uses in the future and offer a solution to the crisis of antimicrobial resistance to traditional approaches. Metal-based nanoparticles have also been extensively studied for many biomedical applications. In addition to reduced size and selectivity for bacteria, metal-based nanoparticles have proven effective against pathogens listed as a priority, according to the World Health Organization (WHO). Moreover, antimicrobial studies of nanoparticles were carried out not only in vitro but in vivo as well in order to investigate their efficacy. In addition, nanomaterials provide numerous opportunities for infection prevention, diagnosis, treatment, and biofilm control. This study emphasizes the antimicrobial effects of nanoparticles and contrasts nanoparticles' with antibiotics' role in the fight against pathogenic microorganisms. Future prospects revolve around developing new strategies and products to prevent, control, and treat microbial infections in humans and other animals, including viral infections seen in the current pandemic scenarios.

Bacteraemia, antimicrobial susceptibility and treatment among Campylobacter-associated hospitalisations in the Australian Capital Territory: a review

BACKGROUND

Campylobacter spp. cause mostly self-limiting enterocolitis, although a significant proportion of cases require hospitalisation highlighting potential for severe disease. Among people admitted, blood culture specimens are frequently collected and antibiotic treatment is initiated. We sought to understand clinical and host factors associated with bacteraemia, antibiotic treatment and isolate non-susceptibility among Campylobacter-associated hospitalisations.

METHODS

Using linked hospital microbiology and administrative data we identified and reviewed Campylobacter-associated hospitalisations between 2004 and 2013. We calculated population-level incidence for Campylobacter bacteraemia and used logistic regression to examine factors associated with bacteraemia, antibiotic treatment and isolate non-susceptibility among Campylobacter-associated hospitalisations.

RESULTS

Among 685 Campylobacter-associated hospitalisations, we identified 25 admissions for bacteraemia, an estimated incidence of 0.71 cases per 100,000 population per year. Around half of hospitalisations (333/685) had blood culturing performed. Factors associated with bacteraemia included underlying liver disease (aOR 48.89, 95% CI 7.03-340.22, p < 0.001), Haematology unit admission (aOR 14.67, 95% CI 2.99-72.07, p = 0.001) and age 70-79 years (aOR 4.93, 95% CI 1.57-15.49). Approximately one-third (219/685) of admissions received antibiotics with treatment rates increasing significantly over time (p < 0.05). Factors associated with antibiotic treatment included Gastroenterology unit admission (aOR 3.75, 95% CI 1.95-7.20, p < 0.001), having blood cultures taken (aOR 2.76, 95% CI 1.79-4.26, p < 0.001) and age 40-49 years (aOR 2.34, 95% CI 1.14-4.79, p = 0.02). Non-susceptibility of isolates to standard antimicrobials increased significantly over time (p = 0.01) and was associated with overseas travel (aOR 11.80 95% CI 3.18-43.83, p < 0.001) and negatively associated with tachycardia (aOR 0.48, 95%CI 0.26-0.88, p = 0.02), suggesting a healthy traveller effect.

CONCLUSIONS

Campylobacter infections result in considerable hospital burden. Among those admitted to hospital, an interplay of factors involving clinical presentation, presence of underlying comorbidities, complications and increasing age influence how a case is investigated and managed.

A prospective observational study describing severity of acquired diarrhea among U.S. military and Western travelers participating in the Global Travelers' Diarrhea Study

BACKGROUND

Travelers' diarrhea (TD) is one of the most common illnesses affecting modern-day travelers, including military personnel. Previous work has shown that afflicted travelers may alter their itineraries and be confined to bed rest due to symptoms, and military personnel may become incapable of completing operational requirements. Examination of signs, symptoms, and severity of diarrheagenic pathogens can inform clinical diagnosis and prioritization of future surveillance and research activities.

METHODS

Utilizing a global laboratory network, culture and molecular testing were performed in parallel at each site on a group of core pathogens, and definitions for acute diarrhea (AD), severe AD, acute gastroenteritis (AGE), and severe AGE were determined using data elements in the modified Vesikari scale. We included 210 cases of TD reporting all variables of interest in our severity assessment analysis.

RESULTS

Out of all cases, 156/210 (74%) met criteria for severe AD and 35/210 (17%) for severe AGE. Examination of severity by pathogen revealed that, at non-military sites, 17/19 (89%) of enteropathogenic Escherichia coli (E. coli) (EPEC) infections, 28/32 (88%) of enterotoxigenic E. coli (ETEC) infections, and 13/15 (87%) of Shigella/enteroinvasive E. coli (EIEC) infections resulted in severe AD cases. At the military site, all infections of ETEC (6/6), Shigella-EIEC (4/4), and enteroaggregative E. coli (EAEC) resulted in AD. Norovirus infections at non-military and military sites resulted in 27% (14/51) and 33% (3/9) severe AGE cases, respectively.

CONCLUSIONS

This study found a high percentage of participants enrolled at both military and non-military sites experienced severe AD with concerning numbers of severe cases at non-military sites reporting hospitalization and reductions in performance. Since travelers with mild TD symptoms are less likely to present to health care workers than those with more severe TD, there is a potential selection bias in this study that may have overestimated the proportion of more severe outcomes among all individuals who could have participated in the GTD study. Future research should examine other covariates among pathogen and host, such as treatment and comorbid conditions, that may contribute to the presence of signs and symptoms and their severity.

Acute Bacterial Gastroenteritis

Acute bacterial gastroenteritis is among the most common infections worldwide, with millions of infections annually in the United States. Much of the illness is foodborne, occurring as both sporadic cases and large multistate outbreaks. Pathogen evolution through genetic exchange of virulence traits and antibiotic resistance determinants poses challenges for empiric therapy. Culture-independent diagnostic tests in clinical laboratories afford rapid diagnosis and expanded identification of pathogens. However, cultures remain important to generate sensitivity data and strain archiving for outbreak investigations. Most infections are self-limited, permitting judicious selection of antibiotic use in more severe forms of illness.

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.

Prevalence and characteristics of Salmonella isolates recovered from retail raw chickens in Shaanxi Province, China

In this study, we evaluated the prevalence of Salmonella in retail raw chickens in Shaanxi Province, China, on a monthly basis. In addition, we studied the antibiotic susceptibility, serotype, and genotype of Salmonella isolates and explored their relationships with sampling time, location, market type, and chicken type. The results showed that Salmonella was more prevalent in chickens sampled during the spring and summer than during the autumn and winter. Thirty-nine serotypes were identified from 406 Salmonella isolates, of which Salmonella typhimurium (16.7%) was the most prevalent. Other prevalent serotypes included S. thompson (12.8%), S. essen (9.1%), S. infantis (6.9%), S. rissen (5.7%), and S. enteritidis (5.4%). Approximately 71.4% of the 406 isolates were resistant to 3 or more antibiotics, 11.8% to 12 or more, and 1.7% to all 14 antibiotics tested. The most frequently detected resistance was to trimethoprim/sulfamethoxazole (82.0%), followed by nalidixic acid (71.9%) and tetracycline (59.4%). The frequencies of resistance to ampicillin, chloramphenicol, and amoxicillin/clavulanic acid were moderately high (∼50% each). Resistance to kanamycin, ceftiofur, streptomycin, gentamicin, and ciprofloxacin was less common (<40% each). Serotype distribution and antibiotic susceptibility of Salmonella isolates were related to sampling time, location, chicken type, and market type. Isolates recovered from the same sampling time, market type, location, and chicken type commonly exhibited identical or similar genotypes and antibiotic resistance profiles. However, DNA profiles and antibiotic resistance phenotypes of isolates within some serotypes were diverse. Our results revealed that multiple Salmonella subtypes with antibiotic resistance were prevalent in retail raw chickens in Shaanxi Province. Our study findings provide information for developing preventive measures against contamination of retail foods with Salmonella.

An Association of an eBURST Group With Triazole Resistance of Candida tropicalis Blood Isolates

Candidemia, a bloodstream infection caused by genus Candida, has a high mortality rate. Candida albicans was previously reported to be the most common causative species among candidemia patients. However, during the past 10 years in Thailand, Candida tropicalis has been recovered from blood more frequently than C. albicans. The cause of this shift in the prevalence of Candida spp. remains unexplored. We conducted in vitro virulence studies and antifungal susceptibility profiles of 48 C. tropicalis blood isolates collected during 2015-2017. To compare to global isolates of C. tropicalis, multilocus sequence typing (MLST), a minimum spanning tree, and an eBURST analysis were also conducted. C. tropicalis and C. albicans were the most (47-48.7%) and second-most (21.5-33.9%) common species to be isolated from candidemia patients, respectively. Of the C. tropicalis blood isolates, 29.2, 0, 100, and 93.8% exhibited proteinase activity, phospholipase activity, hemolytic activity, and biofilm formation, respectively. Moreover, 20.8% (10/48) of the isolates were resistant to voriconazole and fluconazole, and also showed high minimum inhibitory concentrations (MICs) to posaconazole and itraconazole. In contrast, most of the isolates were susceptible to anidulafungin (97.9%), micafungin (97.9%), and caspofungin (97.9%), and showed low MICs to amphotericin B (100%) and 5-flucytosine (100%). The MLST identified 22 diploid sequence types. Based on the eBURST analysis and minimum spanning tree, 9 out of 13 members (69.2%) of an eBURST group 3 were resistant to voriconazole and fluconazole, and also showed high MICs to posaconazole and itraconazole. Association analysis revealed the eBURST group 3 was significantly associated with the four triazole resistance (p < 0.001). In conclusion, the eBURST group 3 was associated with the triazole resistance and resistance to many antifungal drugs might be collectively responsible for the prevalence shift.

Prevalence and antimicrobial susceptibility of Salmonella and Shigella species isolated from diarrheic children in Ambo town

BACKGROUND

Diarrhea, particularly of enteric bacterial pathogen, remains a major cause of morbidity and mortality in Ethiopia. Despite the high prevalence of diarrheal disease among under-five children, antibiotic resistance of bacterial pathogens test is not part of routine childcare in the study area. This study aimed to investigate the prevalence and antimicrobial susceptibility status of Salmonella and Shigella species among diarrheic children attending public health institutions in Ambo town, west Showa, Ethiopia.

METHODS

Institutional based, cross-sectional study was carried out from January to July 2014 among 239 diarrheic children below five years of age in Ambo town, Ethiopia. Information about patient demographics, signs, and symptoms was obtained from the parents/guardians of each child using a questionnaire. Stool samples from diarrheic children were collected and processed for isolation of Salmonella and Shigella using conventional microbiology procedures. Suspected Salmonella isolates were confirmed by genus-specific PCR and serotyped using a slide agglutination test. Susceptibility to 10 commonly used antimicrobials was assessed using the Kirby Bauer disc diffusion method.

RESULTS

From the 239 children screened, only nine (3.8%) of them were positive for either Salmonella (n = 3) or Shigella (n = 6) and 19 (7.9%) positive for the intestinal parasite. Three species of Shigella were identified: Shigella flexinari (n = 3), Shigella boydii (n = 2), and Shigella sonnei (n = 1). The three Salmonella isolates were S. chicago, S. caracas, and S. saintpaul. Salmonella and Shigella isolates were resistant to ampicillin (88.9%), followed by tetracycline (66.7%), cotrimoxazole (55.6%), chloramphenicol (44.4%), amoxicillin (33.3%), nalidixic acid (11.1%) and cefotaxime (11.1%). All isolates were sensitive to amikacin, ciprofloxacin, and gentamycin.

CONCLUSION

In this study, either Salmonella or Shigella species were detected only in 3.8% of diarrheic children in Ambo town, suggesting the dominance of other causes of diarrhea in the study area. A further study targeting other causes of diarrhea should be conducted to establish the major causes of childhood diarrhea in the study area.

Screening of Metal and Antibiotic Resistance in Beta-lactamase Producing Coliform Bacteria from Hospital Wastewater of Northern India

AIMS

Our exploration work has uncovered the different anti-toxin/metal tolerance and patterns against the heavy metal resistant coliform microscopic organisms from the aquatic waste of the hospital. It might give new routes for the treatment of irresistible ailments particularly by coliform and critical for hazard evaluation as well as hazard management associated with the effluents of the hospital.

BACKGROUND

The higher use of pharmaceuticals, Radionuclides, and other antimicrobial solvents are the major source of metals in hospital wastewater. The hospital aquatic environment has a high content of both organic and inorganic matter with living organisms. Bacteria can resist an antimicrobial agent by producing extracellular enzymes that eliminate antibiotics and metal toxicity. In this study, we covered the existing patent literature in this area. New patents in the areas of topically applied antibiotics and agents that can potentiate the achievement of existing antibiotics may extend their helpful lifetime.

METHODS

Samples were collected from three different Departments of King George Medical University, Lucknow during the month of December to May (2015-16). Isolation and metal tolerance of coliform isolates were done on metal amended plates. The antibiotic sensitivity test was done by disc diffusion method. The plasmid DNA of bacterial isolates was done by the alkaline lysis method. The conjugation study was also performed in wastewater as well as a nutrient medium.

RESULTS

Maximum isolates demonstrated their MICs at 400, 800 and 1600 μg/ml against all the metals, respectively. The high level of resistance was observed against Methicillin (88.32%, 80.60%) followed by penicillin (75%, 76%), Cephradin (59.52%, 28.84%) and least to Gentamycine (1.92%, 5.76) in E. coli and Enterobacter, respectively. Of 70%, 78% E. coli and Enterobacter isolates produce beta-lactamase activity. Six amino acid residues namely, Glu104, Tyr105, Asn132, Asn170, Ala237, and Gly238 of the beta-lactamase were found in the common interaction with the selected drugs. Plasmid DNA size ranged between 48-58.8 kb. The conjugation experiments showed a higher transfer frequency (5.5×10-1 and 3.6×10-1) rate among antibiotics and metals tested.

CONCLUSION

The finding of this study presents a potential health problem as the predominant coliform species have increasingly been associated with outbreaks of hospital infections. It is recommended that hospital waste must be properly treated before its release into the environment.

Prevalence and antimicrobial profile of Shigella isolates in a tertiary care hospital of North Karnataka: A 12-year study

Context

Shigella is a common cause of bacillary dysentery. Although it is reported worldwide, the majority of the infections are seen in developing countries with Shigella flexneri being the most common isolate. Prevalence of Shigella species and their antibiotic susceptibility profiles vary according to geographic area and season.

Aims

In the present study, the epidemiology and antimicrobial profile of Shigella from stool samples received at our hospital for a period of 12 years (January 2006 to December 2017) was evaluated.

Subjects and Methods

A total of 4578 stool samples were collected from the cases of acute gastroenteritis and diarrhoea. Samples were processed for culture and sensitivity according to standard microbiological techniques. The presumptive identification of Shigella species was done using standard conventional biochemical tests and confirmed using antisera.

Results

A total of 189 (4.2%) samples yielded Shigella spp. Isolation of Shigella spp. were more frequent from males (58.2%). S. flexneri was the commonest species isolated (47.6%) followed by Shigella sonnei(11.6%), Shigella dysenteriae (4.2%) and Shigella boydii (2.1%). Non-typeable Shigella was commonly recovered. The isolates showed high resistance to ampicillin (76.7%) and co-trimoxazole (75%) while highest susceptibility was observed to ceftriaxone (79.2%).

Conclusions

S. flexneri was the most prevalent species isolated at this centre. Shigella isolates from the study showed alarming resistance to recommended antibiotics. Non-typeable Shigella accounted for 34.4% isolates. Molecular discrimination between Shigella and Escherichia coli is essential.

New Tools to Test Stool: Managing Travelers' Diarrhea in the Era of Molecular Diagnostics

Travelers' diarrhea affects up to 60% of visitors to tropical and subtropical regions. Although symptoms are generally self-limited, some infections are associated with significant morbidity and occasional mortality. Newer molecular diagnostic techniques allow for highly sensitive, specific, and expeditious testing of a wide range of potential pathogens. Identification of the causative pathogen of travelers' diarrhea allows for targeted therapy and management and a reduction in empiric broad-spectrum coverage.

Transferable Mechanisms of Quinolone Resistance from 1998 Onward

While the description of resistance to quinolones is almost as old as these antimicrobial agents themselves, transferable mechanisms of quinolone resistance (TMQR) remained absent from the scenario for more than 36 years, appearing first as sporadic events and afterward as epidemics. In 1998, the first TMQR was soundly described, that is, QnrA. The presence of QnrA was almost anecdotal for years, but in the middle of the first decade of the 21st century, there was an explosion of TMQR descriptions, which definitively changed the epidemiology of quinolone resistance. Currently, 3 different clinically relevant mechanisms of quinolone resistance are encoded within mobile elements: (i) target protection, which is mediated by 7 different families of Qnr (QnrA, QnrB, QnrC, QnrD, QnrE, QnrS, and QnrVC), which overall account for more than 100 recognized alleles; (ii) antibiotic efflux, which is mediated by 2 main transferable efflux pumps (QepA and OqxAB), which together account for more than 30 alleles, and a series of other efflux pumps (e.g., QacBIII), which at present have been sporadically described; and (iii) antibiotic modification, which is mediated by the enzymes AAC(6')Ib-cr, from which different alleles have been claimed, as well as CrpP, a newly described phosphorylase.

Ashworth A, Ricke SC. A Historical Review on Antibiotic Resistance of Foodborne Campylobacter

Campylobacter is one of the most commonly reported foodborne human bacterial gastrointestinal pathogens. Campylobacter is the etiological agent of campylobacteriosis, which is generally a self-limited illness and therefore does not require treatment. However, when patients are immunocompromised or have other co-morbidities, antimicrobial treatment may be necessary for clinical treatment of campylobacteriosis, macrolides and fluoroquinolones are the drugs of choices. However, the increase in antimicrobial resistance of Campylobacter to clinically important antibiotics may become insurmountable. Because of the transmission between poultry and humans, the poultry industry must now allocate resources to address the problem by reducing Campylobacter as well as antimicrobial use, which may reduce resistance. This review will focus on the incidence of antibiotic-resistant Campylobacter in poultry, the clinical consequences of this resistance, and the mechanisms of antibiotic resistance associated with Campylobacter.

Epidemiology and etiology of Traveler's diarrhea in Bangkok, Thailand, a case-control study

Background

Traveler’s diarrhea (TD) is a common health problem among visitors from developed to developing countries. Although global and regional estimates of pathogen distribution are available, the etiology of diarrhea among non-military travelers to Thailand is largely unknown.

Methods

A prospective TD case-control study was conducted among adult travelers from developed countries at a prominent hospital in Bangkok, Thailand during 2001–2003. Stool samples were collected from acute TD cases and non-diarrheal controls and analyzed for bacterial, viral, and protozoan pathogens by microbiology, ELISA or PCR methods. Calculation of adjusted odd ratios for risk factors was performed by logistic regression using STATA statistical software.

Results

Stool samples were collected and analyzed from 389 TD cases and 400 non-diarrhea controls. At least one pathogen was detected in 227 (58%) cases and 124 (31%) controls. Plesiomonas (14%), Vibrio (14%), Campylobacter (14%), and norovirus (12%) were the most frequently isolated pathogens among cases and significantly associated with diarrhea at p = 0.006, p < 0.001, p < 0.001, p < 0.001, respectively. Shigella (3%) and ETEC (8%), detected in lower prevalence, also showed significant association with TD at p < 0.001 and p = 0.002, respectively. Travelers from East Asian countries had an increased risk of Vibrio infection (Crude odds ratio: 3.1, p-value = 0.001); travelers from the United States, Canada, and Europe had an increased risk of Campylobacter infection (Crude odds ratio: 2.6, p-value = 0.001); and travelers from Australia and New Zealand had an increased risk of Salmonella infection (Crude odds ratio: 3.2, p-value = 0.009).

Conclusions

Etiology of TD in Thailand is mainly of bacterial origin. Plesiomonas, Vibrio, and norovirus are underappreciated diarrheagenic pathogens. In our study, the origin of the traveler plays an important role in diarrhea etiology. Understanding variations in TD severity and etiology among travelers from different regions warrants further study.

Electronic supplementary material

The online version of this article (10.1186/s40794-019-0085-9) contains supplementary material, which is available to authorized users.

A review of antibiotic prophylaxis for traveler's diarrhea: past to present

As there is rapid increase in international travel to tropical and subtropical countries, there will likely be more people exposed to diarrheal pathogens in these moderate to high risk areas and subsequent increased concern for traveler’s diarrhea. The disease may appear as a mild clinical syndrome, yet a more debilitating presentation can lead to itinerary changes and hospitalization. As bacterial etiologies are the most common causative agents of TD, the use of antibiotic prophylaxis to prevent TD has been reported among travelers for several years. The most common type of antibiotic used for TD has changed over 50 years, depending on many influencing factors. The use of antibiotic prophylaxis for TD prevention in travelers is still controversial, mainly because of difficulties balancing the risks and benefits. Many factors, such as emerging drug resistance, side effects, cost and risk behavior need to be considered. This article aims to review antibiotic prophylaxis from the 1950s to 2000s, to describe the trend and reasons for different antibiotic use in each decade. We conclude that prophylactic antibiotics should be restricted to some high-risk travelers or short-term critical trips.

Distribution and dissemination of antimicrobial-resistant Salmonella in broiler farms with or without enrofloxacin use

BACKGROUND

Salmonella is a major zoonotic food-borne pathogen that persists on poultry farms, and animals undergo reinfection with endemic strains. The present study aimed to investigate the characteristics and dissemination of antimicrobial-resistant Salmonella within and between broiler farms that used enrofloxacin and those that did not.

RESULTS

Cloacal and environmental (litter, feed, and water) samples from two selected flocks in each of 12 farms owned by the same company were collected three times over a 30-day period of two production cycles during 2015-2016. The rate of Salmonella isolation was 7.8% (123/1584). Nine Salmonella serotypes (116 isolates) and seven untypable isolates were identified, and Salmonella Montevideo was the most prevalent serotype. Azithromycin-resistant (17.9%) and colistin-resistant (3.3%) isolates were detected, and multidrug-resistant isolates (43.1%) were also observed. No isolate was resistant to enrofloxacin or ciprofloxacin; however, intermediate resistance to enrofloxacin was significantly higher (P < 0.05) in farms that used enrofloxacin than in those that did not. The rate of multi-drug resistance among litter isolates (25/44, 56.8%) was significantly higher (P < 0.05) than that among cloacal swab (24/67, 35.8%) and feed (4/12, 33.3%) isolates. Pulsed-field gel electrophoresis (PFGE) analysis of strains of the same serotype was conducted to determine their epidemiological relationship. The PFGE types were classified into 31 groups with a 100% correlation cutoff in dendrograms for Salmonella Montevideo isolates, which showed 100% genomic identity based on age, sample type, flock, and production cycle within and between farms.

CONCLUSION

The present study highlights the occurrence of horizontal transmission and cyclic contamination with antimicrobial-resistant Salmonella in broiler farms owned by the same company. Litter may be a good indicator of indoor environmental contamination with antimicrobial-resistant Salmonella on farms. Additionally, enrofloxacin use may be one of the factors promoting resistance towards it in Salmonella.

Preface: Guidelines for the Treatment of Travelers' Diarrhea in Deployed Military Personnel

Diarrheal disease frequently affects military personnel deployed to developing countries, resulting in decreased job performance and potential negative impacts on military operational readiness. Travelers' diarrhea is a self-limiting illness; however, antibiotic treatment (with and without use of adjunct loperamide therapy) has been shown to significantly reduce clinical presentation of symptoms and duration of illness. Nonetheless, the choice of first-line antibiotics must be carefully considered as increasing resistance of enteric pathogens in endemic regions has rendered many first-line antibiotics ineffective (e.g., Campylobacter spp. are resistant to fluoroquinolones in Southeast Asia). Presently, there are no standardized recommendations for the treatment of travelers' diarrhea among deployed military personnel. Therefore, an expert panel was convened to develop evidence-based, consensus-driven guidelines that address key clinical issues related to self-treatment, antibiotic treatment for acute watery diarrhea and febrile diarrhea/dysentery, and diagnostics. These guidelines "Management of Acute Diarrheal Illness during Deployment" are published in this supplement along with articles reviewing the evidence-based data that supported their development.

Impact of human Campylobacter infections in Southeast Asia: The contribution of the poultry sector

Campylobacter is globally recognized as a major cause of foodborne infection in humans, whilst the development of antimicrobial resistance and the possibility of repelling therapy increase the threat to public health. Poultry is the most frequent source of Campylobacter infection in humans, and southeast Asia is a global leader in poultry production, consumption, and exports. Though three of the world's top 20 most populated countries are located in southeast Asia, the true burden of Campylobacter infection in the region has not been fully elucidated. Based on published data, Campylobacter has been reported in humans, animals, and food commodities in the region. To our knowledge, this study is the first to review the status of human Campylobacter infection in southeast Asia and to discuss future perspectives. Gaining insight into the true burden of the infection and prevalence levels of Campylobacter spp. in the southeast Asian region is essential to ensuring global and regional food safety through facilitating improvements in surveillance systems, food safety regulations, and mitigation strategies.

Antibiotic resistance trends and mechanisms in the foodborne pathogen,Campylobacter

Campylobacteris a major foodborne pathogen and is commonly present in food producing animals. This pathogenic organism is highly adaptable and has become increasingly resistant to various antibiotics. Recently, both the Centers for Disease Control and Prevention and the World Health Organization have designated antibiotic-resistantCampylobacteras a serious threat to public health. For the past decade, multiple mechanisms conferring resistance to clinically important antibiotics have been described inCampylobacter, and new resistance mechanisms constantly emerge in the pathogen. Some of the recent examples include theerm(B)gene conferring macrolide resistance, thecfr(C)genes mediating resistance to florfenicol and other antimicrobials, and a functionally enhanced variant of the multidrug resistance efflux pump, CmeABC. The continued emergence of new resistance mechanisms illustrates the extraordinary adaptability ofCampylobacterto antibiotic selection pressure and demonstrate the need for innovative strategies to control antibiotic-resistantCampylobacter. In this review, we will briefly summarize the trends of antibiotic resistance inCampylobacterand discuss the mechanisms of resistance to antibiotics used for animal production and important for clinical therapy in humans. A special emphasis will be given to the newly discovered antibiotic resistance.

A meta-analysis of the use of rifaximin to prevent travellers' diarrhoea

BACKGROUND

Travellers' diarrhoea affects tens of millions of people travelling to less developed countries or regions annually. There are positive reports of the use of rifaximin, a non-absorbed, gut-selective antibiotic to prevent travellers' diarrhoea. This study will critically review and analyse clinical trials on the subject.

METHODS

Using the keywords [diarrhoea OR diarrhoea OR travel*] AND [rifaximin OR xifaxan OR xifaxanta OR normix OR rifagut], a preliminary search on the PubMed and Ovid databases yielded 411 papers published in English between 1 January 1988 and 1 July 2016. Of these, there were only five relevant clinical trials.

RESULTS

The clinical trials were double-blind, placebo-controlled, randomized trials with a total of 879 subjects. The meta-analysis found significant reduction in risk of travellers' diarrhoea with rifaximin use compared to placebo (pooled RR 0.478, 95% CI: 0.375-0.610, and P  < 0.001). For the entire travel and follow-up period, the risk of developing travellers' diarrhoea was significantly greater in individuals receiving the placebo than those receiving rifaximin (daily doses of 400-600 mg). Overall, rifaximin offered significant protection rates of 48-72%, with lower protection rates for Asian than Latin American countries. In terms of tolerability, similar rates of adverse events were reported for the rifaximin and placebo group ( P  > 0.05), with no clinically significant or serious adverse events related to rifaximin use.

CONCLUSIONS

There is good evidence supporting the use of rifaximin as a chemoprophylactic agent against travellers' diarrhoea, especially in individuals who are at high risk of severe complications from acute infectious diarrhoea. Rifaximin has an excellent tolerability/safety profile and demonstrated efficacy against diarrhoeagenic Escherichia coli and even enteroinvasive bacteria such Campylobacter species. Future studies should study the most effective dosing regimen for rifaximin chemoprophylaxis, as well as profile local antimicrobial resistance/susceptibility data in less developed regions to further guide rifaximin use.

Antibiotic Therapy for Acute Watery Diarrhea and Dysentery

Diarrheal disease affects a large proportion of military personnel deployed to developing countries, resulting in decreased job performance and operational readiness. Travelers' diarrhea is self-limiting and generally resolves within 5 days; however, antibiotic treatment significantly reduces symptom severity and duration of illness. Presently, azithromycin is the preferred first-line antibiotic for the treatment of acute watery diarrhea (single dose 500 mg), as well as for febrile diarrhea and dysentery (single dose 1,000 mg). Levofloxacin and ciprofloxacin are also options for acute watery diarrhea (single dose 500 mg and 750 mg, respectively) and febrile diarrhea/dysentery in areas with high rates of Shigella (500 mg once for 3 days [once daily with levofloxacin and twice daily with ciprofloxacin]), but are becoming less effective because of increasing fluoroquinolone resistance, particularly among Campylobacter spp. Another alternate for acute watery diarrhea is rifaximin (200 mg 3 times per day for 3 days); however, it should not be used with invasive illness. Use of loperamide in combination with antibiotic treatment is also beneficial as it has been shown to further reduce gastrointestinal symptoms and duration of illness. Because of regional differences in the predominance of pathogens and resistance levels, choice of antibiotic should take travel destination into consideration.

Management of Acute Diarrheal Illness During Deployment: A Deployment Health Guideline and Expert Panel Report

BACKGROUND

Acute diarrheal illness during deployment causes significant morbidity and loss of duty days. Effective and timely treatment is needed to reduce individual, unit, and health system performance impacts.

METHODS

This critical appraisal of the literature, as part of the development of expert consensus guidelines, asked several key questions related to self-care and healthcare-seeking behavior, antibiotics for self-treatment of travelers' diarrhea, what antibiotics/regimens should be considered for treatment of acute watery diarrhea and febrile diarrhea and/or dysentery, and when and what laboratory diagnostics should be used to support management of deployment-related travelers' diarrhea. Studies of acute diarrhea management in military and other travelers were assessed for relevance and quality. On the basis of this critical appraisal, guideline recommendations were developed and graded by the Expert Panel using good standards in clinical guideline development methodology.

RESULTS

New definitions for defining the severity of diarrhea during deployment were established. A total of 13 graded recommendations on the topics of prophylaxis, therapy and diagnosis, and follow-up were developed. In addition, four non-graded consensus-based statements were adopted.

CONCLUSIONS

Successful management of acute diarrheal illness during deployment requires action at the provider, population, and commander levels. Strong evidence supports that single-dose antimicrobial therapy is effective in most cases of moderate to severe acute diarrheal illness during deployment. Further studies are needed to address gaps in available knowledge regarding optimal therapies for treatment, prevention, and laboratory testing of acute diarrheal illness.

Antibiotic resistance in Campylobacter and other diarrheal pathogens isolated from US military personnel deployed to Thailand in 2002-2004: a case-control study

Background

Campylobacter continues to be an important cause of diarrheal disease worldwide and a leading cause in Southeast Asia. Studies of US soldiers and marines deployed to Thailand for a 2 to 3 week field exercise provide a unique population in which to study traveler’s diarrhea.

Methods

A case–control study of 217 deployed military personnel was conducted from 2002 through 2004. Of these, 155 subjects who presented to a field medical unit with acute diarrhea were enrolled as cases. These subjects referred an additional 62 diarrhea-free colleagues who served as controls. Frequencies of isolation of Campylobacter spp. and other enteric pathogens were compared in cases and controls, and antibiotic resistance of isolates was described.

Results

Of the 155 subjects with diarrhea, Campylobacter spp. was the most commonly identified pathogen, found in 54 (35%) of the subjects, followed by non-typhoidal Salmonella species found in 36 (23%) subjects. Of the 57 separate C. jejuni and C. coli isolates from these individuals, 51 (89%) were resistant to ciprofloxacin by the disc diffusion method. Nearly one-third of the Campylobacter species were resistant to ampicillin and trimethoprim-sulfamethoxazole. Resistance to azithromycin remained low at 2% (n = 1).

Conclusions

The significant morbidity and marked fluoroquinolone resistance associated with Campylobacter infections in Thailand are important considerations for clinicians providing counseling on appropriate antibacterial regimens for civilian and military travelers.

A Review on Antibiotic Resistance: Alarm Bells are Ringing

Antibiotics are the 'wonder drugs' to combat microbes. For decades, multiple varieties of antibiotics have not only been used for therapeutic purposes but practiced prophylactically across other industries such as agriculture and animal husbandry. Uncertainty has arisen, as microbes have become resistant to common antibiotics while the host remains unaware that antibiotic resistance has emerged. The aim of this review is to explore the origin, development, and the current state of antibiotic resistance, regulation, and challenges by examining available literature. We found that antibiotic resistance is increasing at an alarming rate. A growing list of infections i.e., pneumonia, tuberculosis, and gonorrhea are becoming harder and at times impossible to treat while antibiotics are becoming less effective. Antibiotic-resistant infections correlate with the level of antibiotic consumption. Non-judicial use of antibiotics is mostly responsible for making the microbes resistant. The antibiotic treatment repertoire for existing or emerging hard-to-treat multidrug-resistant bacterial infections is limited, resulting in high morbidity and mortality report. This review article reiterates the optimal use of antimicrobial medicines in human and animal health to reduce antibiotic resistance. Evidence from the literature suggests that the knowledge regarding antibiotic resistance in the population is still scarce. Therefore, the need of educating patients and the public is essential to fight against the antimicrobial resistance battle.

Fluoroquinolone and macrolide resistance in Campylobacter jejuni isolated from broiler slaughterhouses in southern Brazil

Campylobacter jejuni is recognized as a leading cause of acute bacterial gastroenteritis in humans. The over-use of antimicrobials in the human population and in animal husbandry has led to an increase in antimicrobial-resistant infections, particularly with fluoroquinolones and macrolides. The aim of the present study was to provide information of the current status of antimicrobial resistance patterns in Campylobacter jejuni from poultry sources. Fifty strains were recovered from broiler slaughterhouses in Rio Grande do Sul state, Brazil, 2012. The strains were investigated for antimicrobial susceptibility against three agents (ciprofloxacin, nalidixic acid and erythromycin) by minimal inhibitory concentrations. The strains were analysed by polymerase chain reaction-restriction fragment length polymorphism for detection of the Thr-86 mutation that confers resistance to ciprofloxacin. In addition, all the strains were tested for the presence of efflux systems (cmeB gene) conferring antimicrobial resistance. The minimum inhibitory concentrations results showed that 98% of isolates were sensitive to erythromycin and most isolates were resistant to ciprofloxacin (94%) and nalidixic acid (90%). A complete correlation was observed between the minimum inhibitory concentrations and PCR-RFLP assay. Finally, the cmeB gene that is responsible for multidrug resistance was detected in 16 isolates out the 50 strains (32%).

Guidelines for the prevention and treatment of travelers' diarrhea: a graded expert panel report

BACKGROUND

: Travelers' diarrhea causes significant morbidity including some sequelae, lost travel time and opportunity cost to both travelers and countries receiving travelers. Effective prevention and treatment are needed to reduce these negative impacts.

METHODS

: This critical appraisal of the literature and expert consensus guideline development effort asked several key questions related to antibiotic and non-antibiotic prophylaxis and treatment, utility of available diagnostics, impact of multi-drug resistant (MDR) colonization associated with travel and travelers' diarrhea, and how our understanding of the gastrointestinal microbiome should influence current practice and future research. Studies related to these key clinical areas were assessed for relevance and quality. Based on this critical appraisal, guidelines were developed and voted on using current standards for clinical guideline development methodology.

RESULTS

: New definitions for severity of travelers' diarrhea were developed. A total of 20 graded recommendations on the topics of prophylaxis, diagnosis, therapy and follow-up were developed. In addition, three non-graded consensus-based statements were adopted.

CONCLUSIONS

: Prevention and treatment of travelers' diarrhea requires action at the provider, traveler and research community levels. Strong evidence supports the effectiveness of antimicrobial therapy in most cases of moderate to severe travelers' diarrhea, while either increasing intake of fluids only or loperamide or bismuth subsalicylate may suffice for most cases of mild diarrhea. Further studies are needed to address knowledge gaps regarding optimal therapies, the individual, community and global health risks of MDR acquisition, manipulation of the microbiome in prevention and treatment and the utility of laboratory testing in returning travelers with persistent diarrhea.

Medications for the prevention and treatment of travellers' diarrhea

BACKGROUND

. Travellers' diarrhea (TD) remains one of the most common illnesses encountered by travellers to less developed areas of the world. Because bacterial pathogens such as enterotoxigenic Escherichia coli (ETEC), enteroaggregative E. coli , Campylobacter spp. and Shigella spp. are the most frequent causes, antibiotics have been useful in both prevention and treatment of TD.

METHODS.

Results of trials that assessed the use of medications for the prevention and treatment of TD were identified through PubMed and MEDLINE searches using search terms 'travellers' diarrhea', 'prevention' and 'treatment'. References of articles were also screened for additional relevant studies.

RESULTS.

Prevention of TD with antibiotics has been recommended only under special circumstances. Doxycycline, trimethoprim-sulfamethoxazole, fluoroquinolones and rifaximin have been used for prevention, but at present the first three antibiotics may have limited use secondary to increasing resistance, leaving rifaximin as the only current option. Bismuth subsalicylate (BSS) (Pepto-Bismol tablets) is also an option for prophylaxis. Treatment with antibiotics has been recommended for moderate to severe TD. Azithromycin is the drug of choice, especially in Asia where Campylobacter is common. Fluoroquinolone antibiotics continue to be effectively used in Latin America and Africa where ETEC is predominant. BSS and loperamide (LOP) also are effective as standalone treatments. LOP may be used alone for treatment of mild TD or in conjunction with antibiotics for treatment of TD.

CONCLUSIONS

. Historically, antibiotic prophylaxis has not been routinely recommended and has been reserved for special circumstances such as when a traveller with an underlying illness cannot tolerate TD. Antibiotics with or without LOP have been useful in shortening the duration and severity of TD. Emerging antibiotic resistance, limited new antibiotic alternatives and faecal carriage of antibiotic-resistant bacteria by travellers may prompt a re-evaluation of classic recommendations for treatment and prevention of TD with antibiotics.

Resistant pathogens as causes of traveller's diarrhea globally and impact(s) on treatment failure and recommendations

BACKGROUND

: Diarrhea is a frequent clinical syndrome affecting international travellers. Bacterial etiologic agents have a long history of emergent antimicrobial resistance against commonly used antibiotics. Current approaches applying first-line antimicrobial therapy are being challenged by increasingly resistant organisms. This review summarizes recent epidemiological and clinical evidence of antibiotic resistance among enteropathogens causing traveller's diarrhea and the subsequent impact on current treatment recommendations.

METHODS

: The PubMed database was systemically searched for articles related to antibiotic susceptibility and diarrheal pathogens.

RESULTS

: Antibiotic resistance related to travellers' diarrhea has increased in recent years. Most notably, fluoroquinolone resistance has expanded from the Campylobacter -associated cases well documented in Southeast Asia in the 1990s to widespread occurrence, as well as increases among other common bacterial enteropathogens including, enterotoxigenic and enteroaggregative Escherichia coli , Shigella and non-typhoidal Salmonella . Multidrug resistance among enteropathogenic Enterobacteriacae and Campylobacter species create further challenges with the selection of empiric therapy. Treatment failures requiring early use of alternative agents, as well as delayed recovery comparable to placebo rates emphasize the impact of antimicrobial resistance on effective treatment.

CONCLUSIONS

: Although there are limitations in the available data, the increasing antibiotic resistance and adverse impact on clinical outcome require continued surveillance and reconsideration of practice guidelines.

ACG Clinical Guideline: Diagnosis, Treatment, and Prevention of Acute Diarrheal Infections in Adults

Acute diarrheal infections are a common health problem globally and among both individuals in the United States and traveling to developing world countries. Multiple modalities including antibiotic and non-antibiotic therapies have been used to address these common infections. Information on treatment, prevention, diagnostics, and the consequences of acute diarrhea infection has emerged and helps to inform clinical management. In this ACG Clinical Guideline, the authors present an evidence-based approach to diagnosis, prevention, and treatment of acute diarrhea infection in both US-based and travel settings.

Evaluation of immunogenicity and protective efficacy of combination heat-killed immunogens from three entero-invasive bacteria in rabbit model

Diarrhea is a very common health problem in both developing and developed countries. Among the major entero-invasive bacteria, Shigella, Salmonella and Campylobacter cause serious problems in different geographic regions. Recently we have shown immunogenicity and protective efficacy of heat killed multi-serotype Shigella immunogen in different animal models. In our present study, we have advanced our research by preparing a combination heat-killed immunogen of three different entero-invasive bacteria, Shigella, Salmonella and Campylobacter. After three doses on 0th, 14th and 28th day of oral immunization with tri-valent heat-killed (TVHK) immunogen in rabbit model, the immunogenicity was determined by differential count of white blood cells and immunoglobulin assay at various time points. During oral immunization differential count of lymphocytes increased where as polymorphonuclear leucocytes (PMN) count decreased. Serum IgG and IgA showed significant elevation during oral immunization and remained at a detectable value upto 120 days. Protection study was performed in both, in vitro and in vivo conditions, using bacteriocidal assay and rabbit ligated ileal loop model, respectively, which conferred protection against homologous bacteria. Moreover, immunoblot assay against whole cell lysate and lipopolysaccharide exhibited significant amount of antigen-specific immunoglobulins raised against three different bacteria which proved that proteins along with lipopolysaccharides played a pivotal role in immunogenicity and protective efficacy. This trivalent heat-killed immunogen could be a low-cost, simple, oral, non-living vaccine candidate for future use against invasive diarrhea.

Summary of the Committee to Advise on Tropical Medicine and Travel (CATMAT) Statement on Travellers' Diarrhea

Background

Most travellers' diarrhea (TD) infections occur during travel to low- and middle-income countries. Type of travel, duration of stay, age of traveller and presence of certain medical conditions are important factors to consider for risk of TD. The Committee to Advise on Tropical Medicine and Travel (CATMAT) assembled a TD working group to develop recommendations on prevention and treatment of TD in travellers. This document is a summary of the Statement on Travellers' Diarrhea.

Methods

Following a systematic review of the literature, recommendations on the prevention and treatment of TD were developed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology to evaluate data quality, benefits and harms of the intervention, and values and preferences of the traveller. Other recommendations were based on a review of the literature and expert opinion.

Recommendations

Using the GRADE methodology, CATMAT concluded that oral cholera vaccine should not be routinely recommended to prevent TD in Canadian travellers. This recommendation was based on moderate quality data that showed this vaccine was not effective in preventing TD in travellers compared to placebo. Bismuth subsalicylate (BSS), fluoroquinolones or rifaximin are options for the prevention of TD based on high-quality data for BSS and fluoroquinolones and moderate evidence for rifaximin. For the treatment of TD, loperamide (alone or in combination with antibiotics), fluoroquinolones, azithromycin and rifaximin are all options, with varying degrees of data quality. Based on available evidence and expert opinion, CATMAT recommends handwashing or the use of hand sanitizer, as well as prudent choice and preparation of food and beverages as best practices for preventing diarrhea while travelling. At this time, a recommendation cannot be made for either the use of probiotics and prebiotics to prevent TD or the use of BSS to treat TD due to insufficient available evidence.

Conclusion

With the exception of BSS for prevention of TD (strong recommendation for use), CATMAT conditionally recommends the use of each of the other GRADE-evaluated preventive and therapeutic products assessed in this Statement. These CATMAT recommendations should be considered as options in the prevention and treatment of TD based on the particular situation of the traveller.

Enteric Bacteria Isolated from Diarrheal Patients in Korea in 2014

OBJECTIVES

The aim of this study was to characterize the pathogens responsible for causing diarrhea according to season, region of isolation, patient age, and sex as well as to provide useful data for the prevention of diarrheal disease.

METHODS

Stool specimens from 14,886 patients with diarrhea were collected to identify pathogenic bacteria from January 2014 to December 2014 in Korea. A total of 3,526 pathogenic bacteria were isolated and analyzed according to season, region of isolation, and the age and sex of the patient.

RESULTS

The breakdown of the isolated pathogenic bacteria were as follows: Salmonella spp. 476 (13.5%), pathogenic Escherichia coli 777 (22.0%), Vibrio parahaemolyticus 26 (0.74%), Shigella spp. 13 (0.37%), Campylobacter spp. 215 (6.10%), Clostridium perfringens 508 (14.4%), Staphylococcus aureus 1,144 (32.4%), Bacillus cereus 356 (10.1%), Listeria monocytogenes 1 (0.03%), and Yersinia enterocolitica 10 (0.3%). The isolation rate trend showed the highest ratio in the summer season from June to September for most of the pathogenic bacteria except the Gram-positive bacteria. The isolation rate of most of the pathogenic bacteria by patient age showed highest ratio in the 0-19 year age range. For isolation rate by region, 56.2% were isolated from cities and 43.8% were isolated from provinces.

CONCLUSION

Hygiene education should be addressed for diarrheal disease-susceptible groups, such as those younger than 10 years, aged 10-19 years, and older than 70 years, and monitoring for the pathogens is still required. In addition, an efficient laboratory surveillance system for infection control should be continued.

Heat killed multi-serotype Shigella immunogens induced humoral immunity and protection against heterologous challenge in rabbit model

Recently we have shown the homologous protective efficacy of heat killed multi-serotype Shigella (HKMS) immunogens in a guinea pig colitis model. In our present study, we have advanced our research by immunizing rabbits with a reduced number of oral doses and evaluating the host's adaptive immune responses. The duration of immunogenicity and subsequently protective efficacy was determined against wild type heterologous Shigella strains in a rabbit luminal model. After three successive oral immunizations with HKMS immunogens, serum and lymphocyte supernatant antibody titer against the heterologous shigellae were reciprocally increased and remained at an elevated level up to 180 days. Serogroup and serotype specific O-antigen of lipopolysaccharide and immunogenic proteins of heterologous challenge strains were detected by immunoblot assay. Up-regulation of IL-12p35, IFN-γ and IL-10 mRNA expression was detected in immunized rabbit peripheral blood mononuclear cells (PBMC) after stimulation with HKMS in vitro. HKMS-specific plasma cell response was confirmed by production of a relatively higher level of HKMS-specific IgG in immunized PBMC supernatant compared to control group. Furthermore, the immunized groups of rabbits exhibited complete protection against wild type heterologous shigellae challenge. Thus HKMS immunogens induced humoral and Th1-mediated adaptive immunity and provided complete protection in a rabbit model. These immunogens could be a broad spectrum non-living vaccine candidate for human use in the near future.

Novel Drug Targets for Food-Borne Pathogen Campylobacter jejuni: An Integrated Subtractive Genomics and Comparative Metabolic Pathway Study

Campylobacters are a major global health burden and a cause of food-borne diarrheal illness and economic loss worldwide. In developing countries, Campylobacter infections are frequent in children under age two and may be associated with mortality. In developed countries, they are a common cause of bacterial diarrhea in early adulthood. In the United States, antibiotic resistance against Campylobacter is notably increased from 13% in 1997 to nearly 25% in 2011. Novel drug targets are urgently needed but remain a daunting task to accomplish. We suggest that omics-guided drug discovery is timely and worth considering in this context. The present study employed an integrated subtractive genomics and comparative metabolic pathway analysis approach. We identified 16 unique pathways from Campylobacter when compared against H. sapiens with 326 non-redundant proteins; 115 of these were found to be essential in the Database of Essential Genes. Sixty-six proteins among these were non-homologous to the human proteome. Six membrane proteins, of which four are transporters, have been proposed as potential vaccine candidates. Screening of 66 essential non-homologous proteins against DrugBank resulted in identification of 34 proteins with drug-ability potential, many of which play critical roles in bacterial growth and survival. Out of these, eight proteins had approved drug targets available in DrugBank, the majority serving crucial roles in cell wall synthesis and energy metabolism and therefore having the potential to be utilized as drug targets. We conclude by underscoring that screening against these proteins with inhibitors may aid in future discovery of novel therapeutics against campylobacteriosis in ways that will be pathogen specific, and thus have minimal toxic effect on host. Omics-guided drug discovery and bioinformatics analyses offer the broad potential for veritable advances in global health relevant novel therapeutics.

Early childhood diarrhoeal diseases and cognition: are we missing the rest of the iceberg?

Risk factors which interfere with cognitive function are especially important during the first 2 years of life - a period referred to as early child development and a time during which rapid growth and essential development occur. Malnutrition, a condition whose effect on cognitive function is well known, has been shown to be part of a vicious cycle with diarrhoeal diseases, and the two pathologies together continue to be the leading cause of illness and death in young children in developing countries. This paper reviews the burden of early childhood diarrhoeal diseases globally and the emerging evidence of their relationship with global disparities in neurocognitive development. The strength of evidence which indicates that the severe childhood diarrhoeal burden may be implicated in cognitive impairment of children from low- and middle-income counties is discussed. Findings suggest that greater investment in multi-site, longitudinal enteric infection studies that assess long-term repercussions are warranted. Furthermore, economic analyses using the concept of human capital should play a key role in advancing our understanding of the breadth and complexities of the health, social and economic ramifications of early childhood diarrhoeal diseases and enteric infections. This broadened awareness can serve to help advocate for more effective interventions, particularly in developing economies.

Antimicrobial susceptibility pattern of nasal Staphylococcus aureus among Dessie Referral Hospital health care workers, Dessie, Northeast Ethiopia

BACKGROUND

Staphylococcus aureus is a major pathogen in skin and soft tissue infections. Methicillin-resistant S. aureus (MRSA) is prevalent in most of the countries in which it is sought. MRSA is one of the important pathogens implicated in hospital-acquired infections. The main objectives of this study were to determine the antimicrobial susceptibility pattern of S. aureus isolates, the prevalence of MRSA, and the nasal carriage rate in healthy hospital staff members.

METHODS

A total of 118 health care workers (HCWs) were enrolled using a cross-sectional study design. Nasal swabs were collected and cultured on mannitol salt agar (MSA). The slide coagulase test was performed. Susceptibility testing was carried out on Mueller-Hinton agar using the modified Kirby-Bauer disk diffusion method with 10 antibiotics.

RESULTS

Of the 118 HCWs, 34 had S. aureus and 15 had MRSA, with overall positivity rates of 28.8% and 12.7%, respectively. None of the S. aureus isolates were sensitive to penicillin. MRSA isolates were resistant to commonly available antibiotics. Only two (13.3%) of the nasal isolates were vancomycin-resistant.

CONCLUSIONS

A high rate of nasal carriage and multidrug-resistant S. aureus was found in this study, indicating the need for standard infection control to prevent transmission in our health care setting.

Increased carriage of macrolide-resistant fecal E. coli following mass distribution of azithromycin for trachoma control

BACKGROUND

Mass drug treatment with azithromycin (MDA) is part of the WHO-endorsed 'SAFE' strategy for trachoma control in endemic communities. MDA has been associated with reduced trachoma prevalence and short-term reductions in other bacterial infections, but can also lead to increased circulation of macrolide-resistant bacteria.

METHODS

We prospectively monitored macrolide resistance in fecal E. coli collected from young children participating in the PRET+ Study in rural Tanzania. MDA was administered in four villages with >10% trachoma prevalence. Four nearby communities with lower trachoma prevalence served as controls. Rectal swabs were collected during cross-sectional surveys performed at baseline, 1, 3 and 6 months after MDA. Fecal E. coli isolates were screened for macrolide susceptibility using disc diffusion and minimum inhibitory concentration methods. Cross-sectional and longitudinal differences in resistance prevalence by MDA exposure were compared using t-tests and logistic regression.

RESULTS

There was no difference in the proportion of individuals carrying azithromycin-resistant E. coli at baseline (0.21 vs. 0.16, P > 0.05). Azithromycin resistance carriage prevalence remained stable over follow-up in non-MDA villages but increased sharply in MDA villages (0.61 at 1 month, 0.42 at 3 months and 0.31 at 6 months). MDA exposure was highly associated with azithromycin resistance carriage at 1 month post-MDA (OR 15.27, P < 0.001) and subsequent surveys. Younger age and recent diarrhoea were also associated with increased odds of resistance (P < 0.01).

CONCLUSIONS

MDA resulted in significantly increased prevalence of macrolide resistance in E. coli. Although MDA is effective for trachoma elimination, it has costs; it is essential to monitor antimicrobial resistance following MDA.

Dense genomic sampling identifies highways of pneumococcal recombination

Evasion of clinical interventions by Streptococcus pneumoniae occurs through selection of non-susceptible genomic variants. We report whole-genome sequencing of 3,085 pneumococcal carriage isolates from a 2.4-km(2) refugee camp. This sequencing provides unprecedented resolution of the process of recombination and its impact on population evolution. Genomic recombination hotspots show remarkable consistency between lineages, indicating common selective pressures acting at certain loci, particularly those associated with antibiotic resistance. Temporal changes in antibiotic consumption are reflected in changes in recombination trends, demonstrating rapid spread of resistance when selective pressure is high. The highest frequencies of receipt and donation of recombined DNA fragments were observed in non-encapsulated lineages, implying that this largely overlooked pneumococcal group, which is beyond the reach of current vaccines, may have a major role in genetic exchange and the adaptation of the species as a whole. These findings advance understanding of pneumococcal population dynamics and provide information for the design of future intervention strategies.

Widespread acquisition of antimicrobial resistance among Campylobacter isolates from UK retail poultry and evidence for clonal expansion of resistant lineages

Background

Antimicrobial resistance is increasing among clinical Campylobacter cases and is common among isolates from other sources, specifically retail poultry - a major source of human infection. In this study the antimicrobial susceptibility of isolates from a UK-wide survey of Campylobacter in retail poultry in 2001 and 2004–5 was investigated. The occurrence of phenotypes resistant to tetracycline, quinolones (ciprofloxacin and naladixic acid), erythromycin, chloramphenicol and aminoglycosides was quantified. This was compared with a phylogeny for these isolates based upon Multi Locus Sequence Typing (MLST) to investigate the pattern of antimicrobial resistance acquisition.

Results

Antimicrobial resistance was present in all lineage clusters, but statistical testing showed a non-random distribution. Erythromycin resistance was associated with Campylobacter coli. For all antimicrobials tested, resistant isolates were distributed among relatively distant lineages indicative of widespread acquisition. There was also evidence of clustering of resistance phenotypes within lineages; indicative of local expansion of resistant strains.

Conclusions

These results are consistent with the widespread acquisition of antimicrobial resistance among chicken associated Campylobacter isolates, either through mutation or horizontal gene transfer, and the expansion of these lineages as a proportion of the population. As Campylobacter are not known to multiply outside of the host and long-term carriage in humans is extremely infrequent in industrialized countries, the most likely location for the proliferation of resistant lineages is in farmed chickens.

Antimicrobial resistance mechanisms among Campylobacter

Campylobacter jejuni and Campylobacter coli are recognized as the most common causative agents of bacterial gastroenteritis in the world. Humans most often become infected by ingesting contaminated food, especially undercooked chicken, but also other sources of bacteria have been described. Campylobacteriosis is normally a self-limiting disease. Antimicrobial treatment is needed only in patients with more severe disease and in those who are immunologically compromised. The most common antimicrobial agents used in the treatment of Campylobacter infections are macrolides, such as erythromycin, and fluoroquinolones, such as ciprofloxacin. Tetracyclines have been suggested as an alternative choice in the treatment of clinical campylobacteriosis but in practice are not often used. However, during the past few decades an increasing number of resistant Campylobacter isolates have developed resistance to fluoroquinolones and other antimicrobials such as macrolides, aminoglycosides, and beta-lactams. Trends in antimicrobial resistance have shown a clear correlation between use of antibiotics in the veterinary medicine and animal production and resistant isolates of Campylobacter in humans. In this review, the patterns of emerging resistance to the antimicrobial agents useful in treatment of the disease are presented and the mechanisms of resistance to these drugs in Campylobacter are discussed.

Resistance mechanisms in Campylobacter jejuni

Campylobacter jejuni is a major cause of food-borne gastroenteritis worldwide. While mortality is low, morbidity imparted by post-infectious sequelae such as Guillain-Barré syndrome, Reiter syndrome/reactive arthritis and irritable bowel syndrome is significant. In addition, the economic cost is high due to lost productivity. Food animals, particularly poultry, are the main reservoirs of C. jejuni. The over-use of antibiotics in the human population and in animal husbandry has led to an increase in antibiotic-resistant infections, particularly with fluoroquinolones. This is problematic because C. jejuni gastroenteritis is clinically indistinguishable from that caused by other bacterial pathogens, and such illnesses are usually treated empirically with fluoroquinolones. Since C. jejuni is naturally transformable, acquisition of additional genes imparting antibiotic resistance is likely. Therefore, an understanding of the antibiotic resistance mechanisms in C. jejuni is needed to provide proper therapy both to the veterinary and human populations.