Transmission Of Antibiotic Resistance Research Articles

A High-Throughput Method for Screening for Genes Controlling Bacterial Conjugation of Antibiotic Resistance.

The rapid horizontal transmission of antibiotic resistance genes on conjugative plasmids between bacterial host cells is a major cause of the accelerating antibiotic resistance crisis. There are currently no experimental platforms for fast and cost-efficient screening of genetic effects on antibiotic resistance transmission by conjugation, which prevents understanding and targeting conjugation. We introduce a novel experimental framework to screen for conjugation-based horizontal transmission of antibiotic resistance between >60,000 pairs of cell populations in parallel. Plasmid-carrying donor strains are constructed in high-throughput. We then mix the resistance plasmid-carrying donors with recipients in a design where only transconjugants can reproduce, measure growth in dense intervals, and extract transmission times as the growth lag. As proof-of-principle, we exhaustively explore chromosomal genes controlling F-plasmid donation within Escherichia coli populations, by screening the Keio deletion collection in high replication. We recover all seven known chromosomal gene mutants affecting conjugation as donors and identify many novel mutants, all of which diminish antibiotic resistance transmission. We validate nine of the novel genes' effects in liquid mating assays and complement one of the novel genes' effect on conjugation (rseA). The new framework holds great potential for exhaustive disclosing of candidate targets for helper drugs that delay resistance development in patients and societies and improve the longevity of current and future antibiotics. Further, the platform can easily be adapted to explore interspecies conjugation, plasmid-borne factors, and experimental evolution and be used for rapid construction of strains.IMPORTANCE The rapid transmission of antibiotic resistance genes on conjugative plasmids between bacterial host cells is a major cause of the accelerating antibiotic resistance crisis. There are currently no experimental platforms for fast and cost-efficient screening of genetic effects on antibiotic resistance transmission by conjugation, which prevents understanding and targeting conjugation. We introduce a novel experimental framework to screen for conjugation-based horizontal transmission of antibiotic resistance between >60,000 pairs of cell populations in parallel. As proof-of-principle, we exhaustively explore chromosomal genes controlling F-plasmid donation within E. coli populations. We recover all previously known and many novel chromosomal gene mutants that affect conjugation efficiency. The new framework holds great potential for rapid screening of compounds that decrease transmission. Further, the platform can easily be adapted to explore interspecies conjugation, plasmid-borne factors, and experimental evolution and be used for rapid construction of strains.

Prevalence of Pseudomonas aeruginosa and other Microorganisms from Mastitis Milk and Their Antimicrobial Resistance Pattern

Background: Mastitis is a multi-etiological disease. It leads to physical, chemical and bacteriological changes in milk and pathological changes in glandular tissues. In the present study, prevalence of mastitis causing organisms with special reference to Pseudomonas aeruginosa and its antibiotic resistance pattern was studied as Pseudomonas spp. is an important organism in harbouring and transmission of antibiotic resistance in environment.Methods: One hundred and one milk samples from mastitic cattle and buffaloes from farms in and around Ludhiana and mastitis cases presented in veterinary clinical complex, GADVASU, Ludhiana, Punjab, India were collected from August 2018 till April 2019. All the samples were processed for isolation of bacteria using different media viz., BHI, EMB, MLA, Cetrimide Agar, BP Agar, Edward’s medium and Blood Agar. After the isolation, all the organisms were subjected to cultural, morphological, biochemical tests and PCR for confirmation. All these isolates (except Bacillus spp. and Serratia marcescens) were screened for their antimicrobial resistance against 15 commonly used antibiotics viz., chloramphenicol, erythromycin, tetracycline, amoxycillin, co-trimoxazole, ciprofloxacin, gentamicin, cephalexin, ofloxacin, sparfloxacin, gatifloxacin, teicoplanin, azithromycin, vancomycin and doxycycline.Result: Out of a total of 101 samples, 86 samples yielded bacterial growth. Out of these 86 samples, 76 (88.37%) samples had a single bacterial growth whereas rest 10 (11.63%) samples had more than one bacterial growth. It was observed after the organisms were subjected to cultural, morphological, biochemical tests and PCR that, a total of 33 (34.02%) Staphylococcus aureus, 24 (24.74%) Escherichia coli, 16 (16.49%) Klebsiella pneumoniae, 5 (5.15%) Pseudomonas aeruginosa, 2 (2.06%) Streptococcus agalactiae, 12 (12.37%) Bacillus spp. and Serratia marcescens 5 (5.15%) were isolated. It was observed that Pseudomonas aeruginosa showed resistance against most of the antibiotics and was sensitive only for ofloxacin (80%) and gentamicin (40%).

Molecular Epidemiology of Antibiotic-Resistant Escherichia coli from Farm-To-Fork in Intensive Poultry Production in KwaZulu-Natal, South Africa.

The increased use of antibiotics in food animals has resulted in the selection of drug-resistant bacteria across the farm-to-fork continuum. This study aimed to investigate the molecular epidemiology of antibiotic-resistant Escherichia coli from intensively produced poultry in the uMgungundlovu District, KwaZulu-Natal, South Africa. Samples were collected weekly between August and September 2017 from hatching to final retail products. E. coli was isolated on eosin methylene blue agar, identified biochemically, and confirmed using polymerase chain reaction (PCR). Susceptibility to 19 antibiotics was ascertained by the Kirby–Bauer disc diffusion method. PCR was used to test for resistance genes. The clonal similarity was investigated using enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR). In total, 266 E. coli isolates were obtained from all the samples, with 67.3% being non-susceptible to at least one antibiotic tested and 6.7% multidrug resistant. The highest non-susceptibility was to ampicillin (48.1%) and the lowest non-susceptibility to ceftriaxone and azithromycin (0.8%). Significant non-susceptibility was observed to tetracycline (27.4%), nalidixic acid (20.3%), trimethoprim-sulfamethoxazole (13.9%), and chloramphenicol (11.7%) which have homologues used in the poultry industry. The most frequently observed resistance genes were blaCTX-M (100%), sul1 (80%), tetA (77%), and tetB (71%). ERIC-PCR grouped isolates into 27 clusters suggesting the spread of diverse clones across the farm-to-fork continuum. This reiterates the role of intensive poultry farming as a reservoir and a potential vehicle for the transmission of antibiotic resistance, with potentially severe public health implications, thus, requiring prompt and careful mitigation measures to protect human and environmental health.

The Sixth Decennial International Conference on Healthcare-Associated Infections Abstracts, March 2020

Global Solutions to Antibiotic Resistance in HealthcareHeld once every 10 years, the Decennial International Conference on Healthcare-Associated Infections reviews the advances of the previous decade as well as the opportunities and trends for the fields of healthcare epidemiology, infectious diseases, and infection prevention and control in the future. Due to the coronavirus disease 2019 (COVID-19) global pandemic, the SHEA Board and the Decennial 2020 Steering and Program Committee made the difficult decision to cancel the Sixth Decennial International Conference on Healthcare-Associated Infections (Decennial 2020), which was slated to take place in March 2020.Given the ongoing global situation with COVID-19, it is essential that healthcare and public health professionals remain in their workplaces and continue to direct and implement the national and international response activities related to COVID-19. Both the SHEA and the Centers for Disease Control and Prevention are aware of the challenges our country is facing at this moment as leaders in public health and infection prevention and control. We understand the vital need to direct time and energy to the critical situation we are facing in this rapidly changing environment.Although the conference has been canceled, we are pleased to present to you this supplemental issue of Infection Control and Hospital Epidemiology featuring select Scientific Abstracts from the Decennial 2020. The program for the Decennial 2020 intended to highlight 3 narrative themes that encapsulate many of the imperatives for driving progress forward in the field:(1) Innovation: The development of novel prevention tools, strategies, diagnostics, and therapeutics has been critical in the progress of infection prevention and in addressing the threat of antibiotic resistance. Further innovation related to healthcare technology, practices, policies, and programs are needed to continue to move toward the goal of eliminating healthcare-associated infections (HAIs) and slowing antibiotic resistance.(2) Data for action: Facilities, states, clinicians, and other stakeholders need data to drive detection and prevention strategies to eliminate HAIs and to combat antibiotic resistance. Improvements in use of surveillance, epidemiologic, clinical, and laboratory data are critical to closing knowledge gaps and allowing the implementation of effective strategies to provide safe care.(3) Addressing AMR without borders: Many factors impact the local and global burden and transmission of antibiotic resistance. To prevent resistant pathogens from spreading within and between healthcare facilities and the environment, constant vigilance and action are needed. The spread of antibiotic resistance does not respect borders. The antibiotic resistance experience of any given facility, region, or country is directly influenced by the movement of colonized or infected patients with its neighboring facilities, regions, and countries. Global success in containing the spread of HAIs and antibiotic resistance will require coordinated responses at the local, regional, and international levels. Public health and healthcare systems must work together to share information to detect and to implement effective practices to prevent infections from occurring and spreading.The abstracts presented in this supplement highlight these themes, and we are excited to share with you all of the exciting research taking place to advance efforts to prevent infections, combat antibiotic resistance, and provide safe healthcare at every encounter.We thank the Abstract Subcommittee for reviewing and selecting the abstracts presented in this supplement. We received a record number of abstracts, and we appreciate the effort each author contributed. The hours of work that our volunteer reviewers contributed was invaluable in selecting high-quality research for the Decennial 2020.Disclaimer: The large number of submitted abstracts and the deadlines associated with publication do not permit full author communication, abstract revisions, or ICHE editorial review. The abstracts are presented, as they were submitted to the Decennial 2020 Program Committee. Although efforts were made to ensure accuracy, some information related to disclosures and funding may be omitted.The Society for Healthcare Epidemiology of America and The Centers for Disease Control and Prevention

Bacteriophages as antibiotic resistance genes carriers in agro-food systems.

Antibiotic resistance genes (ARGs) are a global health concern. Antibiotic resistance occurs naturally, but misuse of antibiotics in humans and animals is accelerating the process of antibiotic resistance emergency, which has been aggravated by exposure to molecules of antibiotics present in clinical and agricultural settings and the engagement of many countries in water reuse especially in Middle East and North Africa region. Bacteriophages have the potential to be significant actors in ARGs transmission through the transduction process. These viruses have been detected along with ARGs in non impacted habitats and in anthropogenic impacted environments like wastewater, reclaimed water and manure amended soil as well as minimally processed food and ready to eat vegetables. The ubiquity of bacteriophages and their persistence in the environment raises concern about their involvement in ARGs transmission among different biomes and the generation of pathogenic-resistant bacteria that pose a great threat to human health. The aim of this review is to give an overview of the potential role of bacteriophages in the dissemination and the transfer of ARGs to pathogens in food production and processing and the consequent contribution to antibiotic resistance transmission through faecal oral route carrying ARGs to our dishes.

Multidrug-Resistant Bacteria Isolated from Different Aquatic Environments in the North of Spain and South of France.

Due to the global progress of antimicrobial resistance, the World Health Organization (WHO) published the list of the antibiotic-resistant “priority pathogens” in order to promote research and development of new antibiotics to the families of bacteria that cause severe and often deadly infections. In the framework of the One Health approach, the surveillance of these pathogens in different environments should be implemented in order to analyze their spread and the potential risk of transmission of antibiotic resistances by food and water. Therefore, the objective of this work was to determine the presence of high and critical priority pathogens included in the aforementioned list in different aquatic environments in the POCTEFA area (North Spain–South France). In addition to these pathogens, detection of colistin-resistant Enterobacteriaceae was included due its relevance as being the antibiotic of choice to treat infections caused by multidrug resistant bacteria (MDR). From the total of 80 analyzed samples, 100% of the wastewater treatment plants (WWTPs) and collectors (from hospitals and slaughterhouses) and 96.4% of the rivers, carried antibiotic resistant bacteria (ARB) against the tested antibiotics. Fifty-five (17.7%) of the isolates were identified as target microorganisms (high and critical priority pathogens of WHO list) and 58.2% (n = 32) of them came from WWTPs and collectors. Phenotypic and genotypic characterization showed that 96.4% were MDR and resistance to penicillins/cephalosporins was the most widespread. The presence of bla genes, KPC-type carbapenemases, mcr-1 and vanB genes has been confirmed. In summary, the presence of clinically relevant MDR bacteria in the studied aquatic environments demonstrates the need to improve surveillance and treatments of wastewaters from slaughterhouses, hospitals and WWTPs, in order to minimize the dispersion of resistance through the effluents of these areas.

Spatial distribution of antibiotic and heavy metal resistance genes in the Black Sea

Antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) are worldwide considered as emerging contaminants of large interest, and a primary threat to human health. It is becoming clear that the environment plays a central role in the transmission, spread, and evolution of antibiotic resistance. Although marine systems have been largely investigated, only a few studies have considered the presence of ARGs in meso- and bathypelagic waters. To date, no molecular based studies have yet been made to investigate the occurrence of ARGs in the Black Sea, the largest meromictic basin in the world, receiving water from a number of important European rivers and their residues of anthropogenic activities in permanently stratified mesopelagic water masses. In this study, we determined the presence and the abundance of five ARGs (blaCTXM, ermB, qnrS, sul2, tetA) and of the heavy metal resistance gene (HMRG) czcA, in different sampling sites in the eastern and western Black Sea, at several depths (up to 1000 m) and various distances from the shoreline. Three ARGs (blaCTXM, sul2, and tetA) and czcA were present in at least 43% of the analysed samples, whereas ermB and qnrS were never detected. In particular, sul2 abundances increased significantly in coastal location, whereas tetA increased with sampling depth. These findings point out the Black Sea as a source of ARGs and HMRGs distributed along the whole water column.

Simulated sunlight-induced inactivation of tetracycline resistant bacteria and effects of dissolved organic matter

The transmission of antibiotic resistance in surface water has attracted much attention due to its increasing threat to human health. The role of sunlight irradiation and the effect of dissolved organic matter (DOM) on the transmission of antibiotic resistance are still unclear. In this study, photo-inactivation of antibiotic resistant bacteria (ARB) was investigated using antibiotic resistant E. coli (AR E. coli) that contained the tetracycline resistance gene (Tc-ARG) as a representative. The results showed that AR E. coli underwent significant photo-inactivation due to the membrane damage induced by direct irradiation and by the generated reactive oxygen species. Simulated sunlight irradiation specifically suppressed the expression of tetracycline resistance, which is attributed to the destruction of tetracycline-specific efflux pump. Tetracycline inhibited the photo-inactivation of AR E. coli due to its selective pressure on tetracycline resistant E. coli and competitive light absorption effect. Suwannee River fulvic acid (SRFA), a representative DOM, promoted the inactivation of AR E. coli and further inhibited the expression of tetracycline resistance gene due to the generation of its excited triplet state, singlet oxygen, and hydroxyl radical. The extracellular Tc-ARG also underwent fast photodegradation under light irradiation and in the presence of SRFA, which leads to the decrease of its transformation efficiency. This study provided insight into the sunlight-induced inactivation of ARB, which is of significance for understanding the transmission of tetracycline resistance in surface water.

The incidence of antibiotic resistance within and beyond the agricultural ecosystem: A concern for public health.

The agricultural ecosystem creates a platform for the development and dissemination of antimicrobial resistance, which is promoted by the indiscriminate use of antibiotics in the veterinary, agricultural, and medical sectors. This results in the selective pressure for the intrinsic and extrinsic development of the antimicrobial resistance phenomenon, especially within the aquaculture‐animal‐manure‐soil‐water‐plant nexus. The existence of antimicrobial resistance in the environment has been well documented in the literature. However, the possible transmission routes of antimicrobial agents, their resistance genes, and naturally selected antibiotic‐resistant bacteria within and between the various niches of the agricultural environment and humans remain poorly understood. This study, therefore, outlines an overview of the discovery and development of commonly used antibiotics; the timeline of resistance development; transmission routes of antimicrobial resistance in the agro‐ecosystem; detection methods of environmental antimicrobial resistance determinants; factors involved in the evolution and transmission of antibiotic resistance in the environment and the agro‐ecosystem; and possible ways to curtail the menace of antimicrobial resistance.

Backyard Bacterial Exchange: A One Health Approach to Studying Antibiotic Resistance Transmission.

Vol. 128, No. 7 Science SelectionOpen AccessBackyard Bacterial Exchange: A One Health Approach to Studying Antibiotic Resistance Transmissionis accompanied byInter-host Transmission of Carbapenemase-Producing Escherichia coli among Humans and Backyard Animals Janet L. Pelley Janet L. Pelley Search for more papers by this author Published:15 July 2020CID: 074002https://doi.org/10.1289/EHP6585View Article in:中文版AboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit AbstractThe ability of bacteria to develop resistance to multiple antibiotics poses a serious threat to human health.1 Scientists are especially alarmed by the increasing failure of antibiotics known as carbapenems, which are considered the drug of last resort for treating multiple drug–resistant infections.2 Researchers have identified carbapenem-resistant Enterobacteriaceae (CRE), including Escherichia coli, in multiple species.3,4 However, there has been scant evidence of direct microbial transfer between humans and animals. Research published in Environmental Health Perspectives now provides such evidence.5“In earlier research,6 we discovered the spread of carbapenem-resistant Enterobacteriaceae in farm animals in China,” says study author Yang Wang, a molecular biologist at the College of Veterinary Medicine, China Agricultural University. Resistant E. coli isolated from the farm animals and humans had similar genotypes, indicating the potential for transmission between the two.7A study of farmers, backyard livestock, and the flies that bother them all revealed that carbapenem-resistant E. coli can circulate among species. Images (left to right): © XiXinXing/Shutterstock; © Gadelshina Dina/Shutterstock; © Lesia Povkh/Shutterstock; © yazirmzm/Shutterstock; © Davdeka/Shutterstock; © Johnathan21/Shutterstock.In some areas of China, large percentages of households raise livestock in their backyards, bringing humans into close contact with animals.8 As part of the Sino-Swedish Integrated Multisectoral Partnership for Antibiotic Resistance Containment project, Wang and his colleagues thus decided to use a One Health approach to investigate CRE transmission in people, their backyard animals, and their environment.The researchers visited 746 rural households across 12 villages surrounding a central city in Shandong Province, China. They collected fecal samples from residents and livestock. At some households, they also captured flies. Household members answered surveys about risk factors for bacterial transmission, such as the variety of animals they raised and whether they used manure as fertilizer. In addition, the researchers took samples from workers and pigs at the two commercial farms closest to the villages.The researchers found carbapenem-resistant E. coli at about 9% of the households but none at the commercial farms. Households were more likely to have resistant bacteria if they used manure (human and/or animal) as fertilizer or raised a variety of animals. The researchers sequenced the DNA of the resistant E. coli and screened for the presence of genes that confer resistance. More than 35% of the resistant E. coli collected from humans shared core genomes with the bacteria from animals, and the resistance genes in E. coli collected from humans were almost identical to those in samples from animals.To determine the direction of transfer between people and livestock, the researchers used a modeling approach called discriminant analysis of principal components to identify the original host of bacterial isolates. Modeling estimated that most of the resistant bacteria cultured from humans originated in dogs, chickens, pigs, or cattle. Likewise, humans, cattle, dogs, and chickens contributed most of the resistant bacteria cultured from pigs. Resistant bacteria isolated from flies came mostly from humans and dogs, chicken isolates came mostly from pigs and dogs, and the single cattle-derived isolate appeared to come from chickens.The study’s unique strength was its comprehensive simultaneous sampling of individual households, their backyard animals, and their immediate environment—represented by flies—says Qijing Zhang, a microbiologist at Iowa State University who was not involved in the study. “By analyzing a close genetic association between bacteria isolated from animals and humans in the same household, the researchers provided very good evidence that people and animals directly exchange carbapenem-resistant bacteria,” he says.The commercial farms were free of carbapenem resistance, perhaps due to better regulation of hygiene and antibiotic use, the authors suggest. But firm conclusions cannot be drawn because the scientists sampled only two commercial farms, and carbapenem resistance has been reported in other industrial livestock settings.9,10The study is notable for its large scale and the way it highlights the fact that backyard farms may be an underestimated source of carbapenem resistance, says Séamus Fanning, a molecular biologist at University College Dublin who also was not involved in the study. “However,” he says, “we don’t really know if the resistant bacteria are coming from hospital settings to farms via the householders or whether carbapenem resistance in the farm animals’ bacteria has arisen due to coselection for resistance to other, more common antibiotics.”Janet L. Pelley, MS, based in Victoria, BC, Canada, writes for Chemical & Engineering News and Frontiers in Ecology and the Environment.

AKSARAY İLİNDE SATIŞA SUNULAN TULUM PEYNİRLERİNDEN İZOLE EDİLEN ENTEROKOKLARIN ANTİBİYOTİK DİRENÇLİLİKLERİ İLE HEMOLİTİK AKTİVİTELERİNİN BELİRLENMESİ

This study aimed to evaluate the hemolytic activity and antibiotic susceptibility of enterococci isolated from Tulum cheese samples sold in Aksaray province. The isolates were identified as E. faecium (n = 30), E. faecalis (n = 25), and E. durans (n = 7) as a result of 16S rRNA gene sequencing. Three strains (E. faecalis ATC12, E. faecium ATC49, and E. faecium ATC54) exhibited ß-hemolytic activity, whereas others were non-hemolytic. Enterococci were found to have an intermediary or high resistance to nalidixic acid (%100), oxacillin (92%), and streptomycin (72.6%), respectively. E. faecalis strains had more resistant phenotypes to various clinically significant antibiotics than E. faecium and E. durans. Multi-drug resistance was found in 41.93% of the isolates. According to the results, Tulum cheese produced in Aksaray could be a potential vehicle for the transmission of antibiotic resistance via the food chain.

Inactivation of sulfonamide antibiotic resistant bacteria and control of intracellular antibiotic resistance transmission risk by sulfide-modified nanoscale zero-valent iron

The inactivation of a gram-negative sulfonamide antibiotic resistant bacteria (ARB) HLS.6 and removal of intracellular antibiotic resistance gene (ARG, sul1) and class I integrase gene (intI1) by nanoscale zero-valent iron (nZVI) and sulfide-modified nZVI (S-nZVI) with different S/Fe molar ratios were investigated in this study. The S-nZVI with high sulfur content (S/Fe = 0.05, 0.1, 0.2) was superior to nZVI and the treatment effect was best when S/Fe was 0.1. The ARB (2 × 107 CFU/mL) could be completely inactivated by 1.12 g/L of S-nZVI (S/Fe = 0.1) within 15 min, and the removal rates of intracellular sul1 and intI1 reached up to 4.39 log and 4.67 log at 60 min, respectively. Quenching experiments and flow cytometry proved that reactive oxygen species and adsorption were involved in the ARB inactivation and target genes removal. Bacterial death and live staining experiments and transmission electron microscopy showed that the ARB cell structure and intracellular DNA were severely damaged after S-nZVI treatment. This study provided a potential alternative method for controlling the antibiotic resistance in aquatic environment.

What is the research evidence for antibiotic resistance exposure and transmission to humans from the environment? A systematic map protocol

BackgroundAntimicrobial resistance (AMR) is a public health crisis that is predicted to cause 10 million deaths per year by 2050. The environment has been implicated as a reservoir of AMR and is suggested to play a role in the dissemination of antibiotic resistance genes (ARGs). Currently, most research has focused on measuring concentrations of antibiotics and characterising the abundance and diversity of ARGs and antibiotic resistant bacteria (ARB) in the environment. To date, there has been limited empirical research on whether humans are exposed to this, and whether exposure can lead to measureable impacts on human health. Therefore, the objective of this work is to produce two linked systematic maps to investigate previous research on exposure and transmission of AMR to humans from the environment. The first map will investigate the available research relating to exposure and transmission of ARB/ARGs from the environment to humans on a global scale and the second will investigate the prevalence of ARB/ARGs in various environments in the UK. These two maps will be useful for policy makers and research funders to identify where there are significant gluts and gaps in the current research, and where more primary and synthesis research needs to be undertaken.MethodsSeparate search strategies will be developed for the two maps. Searches will be run in 13 databases, and grey literature will be sought from key websites and engagement with experts. Hits will be managed in EndNote and screened in two stages (title/abstract then full text) against predefined inclusion criteria. A minimum of 10% will be double screened with ongoing consistency checking. All included studies will have data extracted into a bespoke form designed and piloted for each map. Data to be extracted will include bibliographic details, study design, location, exposure source, exposure route, health outcome (Map 1); and prevalence/percentage of ARB/ARG (Map 2). No validity appraisal will be undertaken. Results will be tabulated and presented narratively, together with graphics showing the types and areas of research that has been undertaken and heatmaps for key exposure-health outcomes (Map 1) and exposure-prevalence (Map 2).

Horizontal Gene Transfer of Antibiotic Resistance from Acinetobacter baylyi to Escherichia coli on Lettuce and Subsequent Antibiotic Resistance Transmission to the Gut Microbiome.

Agricultural use of antibiotics is recognized by the U.S. Centers for Disease Control and Prevention as a major contributor to antibiotic-resistant infections. While most One Health attention has been on the potential for antibiotic resistance transmission from livestock and contaminated meat products to people, plant foods are fundamental to the food chain for meat eaters and vegetarians alike. We hypothesized that environmental bacteria that colonize plant foods may serve as platforms for the persistence of antibiotic-resistant bacteria and for horizontal gene transfer of antibiotic-resistant genes. Donor Acinetobacter baylyi and recipient Escherichia coli were cocultured in vitro, in planta on lettuce, and in vivo in BALB/c mice. We showed that nonpathogenic, environmental A. baylyi is capable of transferring plasmids conferring antibiotic resistance to E. coli clinical isolates on lettuce leaf discs. Furthermore, transformant E. coli from the in planta assay could then colonize the mouse gut microbiome. The target antibiotic resistance plasmid was identified in mouse feces up to 5 days postinfection. We specifically identified in vivo transfer of the plasmid to resident Klebsiella pneumoniae in the mouse gut. Our findings highlight the potential for environmental bacteria exposed to antibiotics to transmit resistance genes to mammalian pathogens during ingestion of leafy greens.IMPORTANCE Previous efforts have correlated antibiotic-fed livestock and meat products with respective antibiotic resistance genes, but virtually no research has been conducted on the transmission of antibiotic resistance from plant foods to the mammalian gut (C. S. Hölzel, J. L. Tetens, and K. Schwaiger, Pathog Dis 15:671-688, 2018, https://doi.org/10.1089/fpd.2018.2501; C. M. Liu et al., mBio 9:e00470-19, 2018, https://doi.org/10.1128/mBio.00470-18; B. Spellberg et al., NAM Perspectives, 2016, https://doi.org/10.31478/201606d; J. O'Neill, Antimicrobials in agriculture and the environment, 2015; Centers for Disease Control and Prevention, Antibiotic resistance threats in the United States, 2019). Here, we sought to determine if horizontal transmission of antibiotic resistance genes can occur between lettuce and the mammalian gut microbiome, using a mouse model. Furthermore, we have created a new model to study horizontal gene transfer on lettuce leaves using an antibiotic-resistant transformant of A. baylyi (AbzeoR).

Characteristics of oral methicillin-resistant Staphylococcus epidermidis isolated from dental plaque

The oral microbial community is widely regarded as a latent reservoir of antibiotic resistance genes. This study assessed the molecular epidemiology, susceptibility profile, and resistance mechanisms of 35 methicillin-resistant Staphylococcus epidermidis (MRSE) strains isolated from the dental plaque of a healthy human population. Broth microdilution minimum inhibitory concentrations (MICs) revealed that all the isolates were nonsusceptible to oxacillin and penicillin G. Most of them were also resistant to trimethoprim (65.7%) and erythromycin (54.3%). The resistance to multiple antibiotics was found to be largely due to the acquisition of plasmid-borne genes. The mecA and dfrA genes were found in all the isolates, mostly dfrG (80%), aacA-aphD (20%), aadD (28.6%), aphA3 (22.9%), msrA (5.7%), and the ermC gene (14.3%). Classical mutational mechanisms found in these isolates were mainly efflux pumps such as qacA (31.4%), qacC (25.7%), tetK (17.1%), and norA (8.6%). Multilocus sequence type analysis revealed that sequence type 59 (ST59) strains comprised 71.43% of the typed isolates, and the eBURST algorithm clustered STs into the clonal complex 2-II(CC2-II). The staphyloccoccal cassette chromosome mec (SCCmec) type results showed that 25 (71.43%) were assigned to type IV. Moreover, 88.66% of the isolates were found to harbor six or more biofilm-associated genes. The aap, atlE, embp, sdrF, and IS256 genes were detected in all 35 isolates. This research demonstrates that biofilm-positive multiple-antibiotic-resistant ST59-SCCmec IV S. epidermidis strains exist in the dental plaque of healthy people and may be a potential risk for the transmission of antibiotic resistance.

Efficient inactivation of antibiotic resistant bacteria and antibiotic resistance genes by photo-Fenton process under visible LED light and neutral pH

Antibiotic resistance has been recognized as a major threat to public health worldwide. Inactivation of antibiotic resistant bacteria (ARB) and degradation of antibiotic resistance genes (ARGs) are critical to prevent the spread of antibiotic resistance in the environment. Conventional disinfection processes are effective to inactivate water-borne pathogens, yet they are unable to completely eliminate the antibiotic resistance risk. This study explored the potential of the photo-Fenton process to inactivate ARB, and to degrade both extracellular and intracellular ARGs (e-ARGs and i-ARGs, respectively). Using Escherichia coli DH5α with two plasmid-encoded ARGs (tetA and blaTEM-1) as a model ARB, a 6.17 log ARB removal was achieved within 30 min of applying photo-Fenton under visible LED and neutral pH conditions. In addition, no ARB regrowth occurred after 48-h, demonstrating that this process is very effective to induce permanent disinfection on ARB. The photo-Fenton process was validated under various water matrices, including ultrapure water (UPW), simulated wastewater (SWW) and phosphate buffer (PBS). The higher inactivation efficiency was observed in SWW as compared to other matrices. The photo-Fenton process also caused a 6.75 to 8.56-log reduction in eARGs based on quantitative real-time PCR of both short- and long amplicons. Atomic force microscopy (AFM) further confirmed that the extracellular DNA was sheared into short DNA fragments, thus eliminating the risk of the transmission of antibiotic resistance. As compared with e-ARGs, a higher dosage of Fenton reagent was required to damage i-ARGs. In addition, the tetA gene was more easily degraded than the blaTEM-1 gene. Collectively, our results demonstrate the photo-Fenton process is a promising technology for disinfecting water to prevent the spread of antibiotic resistance.

Nanotechnological solutions for controlling transmission and emergence of antimicrobial-resistant bacteria, future prospects, and challenges: a systematic review

Globally, a high prevalence of multi-drug-resistant (MDR) bacteria, mostly methicillin-resistant Staphylococcus aureus and carbapenem-resistant Enterobacteriaceae, has been reported. Infections caused by such bacteria are expensive and hard to treat due to reduced efficient treatment alternatives. Centered on the current rate of antibiotics production and approvals, it is anticipated that by 2050 up to 10 million people could die annually due to MDR pathogens. To this effect, alternative strategies such as the use of nanotechnology to formulate nanobactericidal agents are being explored. This systematic review addresses the recent approaches, future prospects, and challenges of nanotechnological solutions for controlling transmission and emergence of antibiotic resistance. A comprehensive literature search of PubMed and BioMed Central databases from June 2018 to January 2019 was performed. The search keywords used were “use of nanotechnology to control antibiotic resistance” to extract articles published only in English encompassing all research papers regardless of the year of publication. PubMed and BioMed Central databases literature exploration generated 166 articles of which 49 full-text research articles met the inclusion guidelines. Of the included articles, 44.9%, 30.6%, and 24.5% reported the use of inorganic, hybrid, and organic nanoparticles, respectively, as bactericidal agents or carriers/enhancers of bactericidal agents. Owing to the ever-increasing prevalence of antimicrobial resistance to old and newly synthesized drugs, alternative approaches such as nanotechnology are highly commendable. This is supported by in vitro, ex vivo, and in vivo studies assessed in this review as they reported high bactericide efficacies of organic, inorganic, and hybrid nanoparticles.

Insights into factors driving the transmission of antibiotic resistance from sludge compost-amended soil to vegetables under cadmium stress

Sludge compost is often used as a fertilizer for crops, although it might be enriched with antibiotic resistance genes (ARGs) and heavy metals that cannot be removed through composting. A robust understanding of the factors affecting the transmission of ARGs to vegetables grown in soils treated with sludge products is lacking. In this study, target ARGs in the bulk and rhizosphere soils and endophytes of shallots under heavy metal stress (i.e., Cd) were assessed, and the factors driving the transmission of ARGs were identified. Cd stress resulted in an increase in the relative abundances of target ARGs in the bulk and rhizosphere soils and endophytes. The driving factors were different in soils and plants under different degrees of Cd stress. The fungal community composition was the main driving factor of ARG variation in both bulk and rhizosphere soils. Moreover, endophytic bacteria played a crucial role in transferring ARGs to plants. Higher Cd stress promoted the transfer of most target ARGs from the below-ground plant parts to the above-ground parts. These findings indicate that application of sludge contaminated with heavy metals, such as Cd, can facilitate the dissemination of ARGs into vegetables, which must be considered while assessing the risks to public health.

Seasonality impels the antibiotic resistance in Kelani River of the emerging economy of Sri Lanka

We evaluated the occurrence of antibiotic-resistant bacteria, antibiotic-resistant gene, and metal concentration in a tropical river of Sri Lanka as a pre-emptive effort to understand the seasonal impact on their prevalence. Resistance for norfloxacin, ciprofloxacin, levofloxacin, kanamycin monosulfate (KM), tetracycline (TC), and sulfamethoxazole (ST) was measured with Kirby–Bauer disc diffusion method. The prevalence of Escherichia coli ranged from 10 to 27 CFU (colony-forming unit) ml−1 in Kelani River in Sri Lanka, and most of the E. coli isolates were resistant to more than one antibiotic. However, the resistance for TC and ST was much higher than other antibiotics. We found that the resistance percentage for older antibiotics like TC and ST was higher than the newer antibiotics. We detected genes that confer resistance to TCs, sulfonamides, β-lactams, and fluoroquinolones. Seasonal variation in the resistance of fluoroquinolones was much higher than the non-fluoroquinolones, but the effect was antagonistic. Overall, the significant seasonal variations imply the importance of mixed source and environmental conditions for development and transmission of antibiotic resistance.

Metadata Analysis of mcr-1-Bearing Plasmids Inspired by the Sequencing Evidence for Horizontal Transfer of Antibiotic Resistance Genes Between Polluted River and Wild Birds.

We sequenced the whole genomes of three mcr-1-positive multidrug-resistant E. coli strains, which were previously isolated from the environment of egret habitat (polluted river) and egret feces. The results exhibit high correlation between antibiotic-resistant phenotype and genotype among the three strains. Most of the mobilized antibiotic resistance genes (ARGs) are distributed on plasmids in the forms of transposons or integrons. Multidrug-resistant (MDR) regions of high homology are detected on plasmids of different E. coli isolates. Therefore, horizontal transfer of resistance genes has facilitated the transmission of antibiotic resistance between the environmental and avian bacteria, and the transfer of ARGs have involved multiple embedded genetic levels (transposons, integrons, plasmids, and bacterial lineages). Inspired by this, systematic metadata analysis was performed for the available sequences of mcr-1-bearing plasmids. Among these plasmids, IncHI2 plasmids carry the most additional ARGs. The composition of these additional ARGs varies according to their geographical distribution. The phylogenetic reconstruction of IncI2 and IncX4 plasmids provides the evidence for their multiregional evolution. Phylogenetic analysis at the level of mobile genetic element (plasmid) provides important epidemiological information for the global dissemination of mcr-1 gene. Highly homologous mcr-1-bearing IncI2 plasmids have been isolated from different regions along the East Asian-Australasian Flyway, suggesting that migratory birds may mediate the intercontinental transportation of ARGs.