Evaluation of an automated feedback intervention to improve antibiotic prescribing among primary care physicians (OPEN Stewardship): a multinational controlled interrupted time-series study.

Tools to advance antimicrobial stewardship in the primary health care setting, where most antimicrobials are prescribed, are urgently needed. The aim of this study was to evaluate OPEN Stewarship (Online Platform for Expanding aNtibiotic Stewardship), an automated feedback intervention, among a cohort of primary care physicians. We performed a controlled, interrupted time-series study of 32 intervention and 725 control participants, consisting of primary care physicians from Ontario, Canada and Southern Israel, from October 2020 to December 2021. Intervention participants received three personalized feedback reports targeting several aspects of antibiotic prescribing. Study outcomes (overall prescribing rate, prescribing rate for viral respiratory conditions, prescribing rate for acute sinusitis, and mean duration of therapy) were evaluated using multilevel regression models. We observed a decrease in the mean duration of antibiotic therapy (IRR = 0.94; 95% CI: 0.90, 0.99) in intervention participants during the intervention period. We did not observe a significant decline in overall antibiotic prescribing (OR = 1.01; 95% CI: 0.94, 1.07), prescribing for viral respiratory conditions (OR = 0.87; 95% CI: 0.73, 1.03), or prescribing for acute sinusitis (OR = 0.85; 95% CI: 0.67, 1.07). In this antimicrobial stewardship intervention among primary care physicians, we observed shorter durations of therapy per antibiotic prescription during the intervention period. The COVID-19 pandemic may have hampered recruitment; a dramatic reduction in antibiotic prescribing rates in the months before our intervention may have made physicians less amenable to further reductions in prescribing, limiting the generalizability of the estimates obtained.IMPORTANCEAntibiotic overprescribing contributes to antibiotic resistance, a major threat to our ability to treat infections. We developed the OPEN Stewardship (Online Platform for Expanding aNtibiotic Stewardship) platform to provide automated feedback on antibiotic prescribing in primary care, where most antibiotics for human use are prescribed but where the resources to improve antibiotic prescribing are limited. We evaluated the platform among a cohort of primary care physicians from Ontario, Canada and Southern Israel from October 2020 to December 2021. The results showed that physicians who received personalized feedback reports prescribed shorter courses of antibiotics compared to controls, although they did not write fewer antibiotic prescriptions. While the COVID-19 pandemic presented logistical and analytical challenges, our study suggests that our intervention meaningfully improved an important aspect of antibiotic prescribing. The OPEN Stewardship platform stands as an automated, scalable intervention for improving antibiotic prescribing in primary care, where needs are diverse and technical capacity is limited.

An Evaluation of the Impact of an OPEN Stewardship Generated Feedback Intervention on Antibiotic Prescribing among Primary Care Veterinarians in Canada and Israel.

An interrupted time-series study design was implemented to evaluate the impact of antibiotic stewardship interventions on antibiotic prescribing among veterinarians. A total of 41 veterinarians were enrolled in Canada and Israel and their prescribing data between 2019 and 2021 were obtained. As an intervention, veterinarians periodically received three feedback reports comprising feedback on the participants' antibiotic prescribing and prescribing guidelines. A change in the level and trend of antibiotic prescribing after the administration of the intervention was compared using a multi-level generalized linear mixed-effect negative-binomial model. After the receipt of the first (incidence rate ratios [IRR] = 0.88; 95% confidence interval (CI): 0.79, 0.98), and second (IRR = 0.85; 95% CI: 0.75, 0.97) feedback reports, there was a reduced prescribing rate of total antibiotic when other parameters were held constant. This decline was more pronounced among Israeli veterinarians compared to Canadian veterinarians. When other parameters were held constant, the prescribing of critical antibiotics by Canadian veterinarians decreased by a factor of 0.39 compared to that of Israeli veterinarians. Evidently, antibiotic stewardship interventions can improve antibiotic prescribing in a veterinary setting. The strategy to sustain the effect of feedback reports and the determinants of differences between the two cohorts should be further explored.

Impact of the COVID-19 pandemic on the surveillance, prevention and control of antimicrobial resistance: a global survey.

OBJECTIVES: The COVID-19 pandemic has had a substantial impact on health systems. The WHO Antimicrobial Resistance (AMR) Surveillance and Quality Assessment Collaborating Centres Network conducted a survey to assess the effects of COVID-19 on AMR surveillance, prevention and control. METHODS: From October to December 2020, WHO Global Antimicrobial Resistance and Use Surveillance System (GLASS) national focal points completed a questionnaire, including Likert scales and open-ended questions. Data were descriptively analysed, income/regional differences were assessed and free-text questions were thematically analysed. RESULTS: Seventy-three countries across income levels participated. During the COVID-19 pandemic, 67% reported limited ability to work with AMR partnerships; decreases in funding were frequently reported by low- and middle-income countries (LMICs; P < 0.01). Reduced availability of nursing, medical and public health staff for AMR was reported by 71%, 69% and 64%, respectively, whereas 67% reported stable cleaning staff availability. The majority (58%) reported reduced reagents/consumables, particularly LMICs (P < 0.01). Decreased numbers of cultures, elective procedures, chronically ill admissions and outpatients and increased ICU admissions reported could bias AMR data. Reported overall infection prevention and control (IPC) improvement could decrease AMR rates, whereas increases in selected inappropriate IPC practices and antimicrobial prescribing could increase rates. Most did not yet have complete data on changing AMR rates due to COVID-19. CONCLUSIONS: This was the first survey to explore the global impact of COVID-19 on AMR among GLASS countries. Responses highlight important actions to help ensure that AMR remains a global health priority, including engaging with GLASS to facilitate reliable AMR surveillance data, seizing the opportunity to develop more sustainable IPC programmes, promoting integrated antibiotic stewardship guidance, leveraging increased laboratory capabilities and other system-strengthening efforts.

Evaluation of an OPEN Stewardship generated feedback intervention to improve antibiotic prescribing among primary care veterinarians in Ontario, Canada and Israel: protocol for evaluating usability and an interrupted time-series analysis.

INTRODUCTION: Antimicrobial resistance (AMR) impacts the health and well-being of animals, affects animal owners both socially and economically, and contributes to AMR at the human and environmental interface. The overuse and/or inappropriate use of antibiotics in animals has been identified as one of the most important drivers of the development of AMR in animals. Effective antibiotic stewardship interventions such as feedback can be adopted in veterinary practices to improve antibiotic prescribing. However, the provision of dedicated financial and technical resources to implement such systems are challenging. The newly developed web-based Online Platform for Expanding Antibiotic Stewardship (OPEN Stewardship) platform aims to automate the generation of feedback reports and facilitate wider adoption of antibiotic stewardship. This paper describes a protocol to evaluate the usability and usefulness of a feedback intervention among veterinarians and assess its impact on individual antibiotic prescribing. METHODS AND ANALYSIS: Approximately 80 veterinarians from Ontario, Canada and 60 veterinarians from Israel will be voluntarily enrolled in a controlled interrupted time-series study and their monthly antibiotic prescribing data accessed. The study intervention consists of targeted feedback reports generated using the OPEN Stewardship platform. After a 3-month preintervention period, a cohort of veterinarians (treatment cohort, n=120) will receive three feedback reports over the course of 6 months while the remainder of the veterinarians (n=20) will be the control cohort. A survey will be administered among the treatment cohort after each feedback cycle to assess the usability and usefulness of various elements of the feedback report. A multilevel negative-binomial regression analysis of the preintervention and postintervention antibiotic prescribing of the treatment cohort will be performed to evaluate the impact of the intervention. ETHICS AND DISSEMINATION: Research ethics board approval was obtained at each participating site prior to the recruitment of the veterinarians. The study findings will be disseminated through open-access scientific publications, stakeholder networks and national/international meetings.

Evaluation of an automated feedback intervention to improve antimicrobial prescribing among primary care physicians (OPEN Stewardship): protocol for an interrupted time-series and usability analysis in Ontario, Canada and Southern Israel.

INTRODUCTION: Antimicrobial resistance undermines our ability to treat bacterial infections, leading to longer hospital stays, increased morbidity and mortality, and a mounting burden to the healthcare system. Antimicrobial stewardship is increasingly important to safeguard the efficacy of existing drugs, as few new drugs are in the developmental pipeline. While significant progress has been made with respect to stewardship in hospitals, relatively little progress has been made in the primary care setting, where the majority of antimicrobials are prescribed. OPEN Stewardship is an international collaboration to develop an automated feedback platform to improve responsible antimicrobial prescribing among primary care physicians and capable of being deployed across heterogeneous healthcare settings. We describe the protocol for an evaluation of this automated feedback intervention with two main objectives: assessing changes in antimicrobial prescribing among participating physicians and determining the usability and usefulness of the reports. METHODS AND ANALYSIS: A non-randomised evaluation of the automated feedback intervention (OPEN Stewardship) will be conducted among approximately 150 primary care physicians recruited from Ontario, Canada and Southern Israel, based on a series of targeted stewardship messages sent using the platform. Using a controlled interrupted time-series analysis and multilevel negative binomial modelling, we will compare the antimicrobial prescribing rates of participants before and after the intervention, and also to the prescribing rates of non-participants (from the same healthcare network) during the same period. We will examine outcomes targeted by the stewardship messages, including prescribing for antimicrobials with duration longer than 7 days and prescribing for indications where antimicrobials are typically unnecessary. Participants will also complete a series of surveys to determine the usability and usefulness of the stewardship reports. ETHICS AND DISSEMINATION: All sites have obtained ethics committee approval to recruit providers and access anonymised prescribing data. Dissemination will occur through open-access publication, stakeholder networks and national/international meetings.

Study protocol for One Health data collections, analyses and intervention of the Sino-Swedish integrated multisectoral partnership for antibiotic resistance containment (IMPACT).

INTRODUCTION: To effectively minimise the emergence and dissemination of antibiotic resistant bacteria, a holistic One Health approach is called for. The Sino-Swedish Integrated Multisectoral Partnership for Antibiotic Resistance Containment is a cross-sectoral and integrated project on antibiotic resistance, conducted in Shandong Province in China. This paper outlines the overall study protocol for the project. To our knowledge, this is the first research programme aiming to take a true holistic approach across multiple sectors simultaneously in China, and the first to incorporate both antibiotic use and infection prevention and control in addition to antibiotic resistance patterns. The project aims to address gaps in current knowledge and seeks to improve the situation through a system-wide intervention. By using a One Health approach we can address important research questions that individual discipline investigations are unable to. The results obtained should thus more closely reflect the world in which human health, animal health and the environment are inextricably and intimately interlinked. METHODS AND ANALYSIS: Both quantitative and qualitative studies are included for households from 12 villages, their surrounding environment and a tertiary care hospital in a nearby town. The studies include analyses of antibiotic consumption for humans and pigs; qualitative and quantitative data on perceptions, knowledge and attitudes; faecal carriage of extended spectrum ß-lactamase and carbapenemase-producing Enterobacteriaceae from pigs and humans, and occurrence in household drinking water, surface water, waste water and clinical bacterial isolates from the hospital. Carriage of methicillin-resistant Staphylococcus aureus in humans, household pigs and clinical bacterial isolates is also investigated. Furthermore, potential inter-relationships between these sources are analysed. A multifaceted One Health intervention is designed and implemented in 6 of the 12 villages. Repeated and continuous data collections take place over 2 years, where the repeated data collection is performed after 1 year of intervention. Comparisons are made between intervention and control villages, before and after the intervention. ETHICS: Ethics approval was obtained from the first Affiliated Hospital, College of Medicine, Zhejiang University, China, reference number 2015#185 and 2015#283.

Lessons learnt during 20 years of the Swedish strategic programme against antibiotic resistance.

Increasing use of antibiotics and rising levels of bacterial resistance to antibiotics are a challenge to global health and development. Successful initiatives for containing the problem need to be communicated and disseminated. In Sweden, a rapid spread of resistant pneumococci in the southern part of the country triggered the formation of the Swedish strategic programme against antibiotic resistance, also known as Strama, in 1995. The creation of the programme was an important starting point for long-term coordinated efforts to tackle antibiotic resistance in the country. This paper describes the main strategies of the programme: committed work at the local and national levels; monitoring of antibiotic use for informed decision-making; a national target for antibiotic prescriptions; surveillance of antibiotic resistance for local, national and global action; tracking resistance trends; infection control to limit spread of resistance; and communication to raise awareness for action and behavioural change. A key element for achieving long-term changes has been the bottom-up approach, including working closely with prescribers at the local level. The work described here and the lessons learnt could inform countries implementing their own national action plans against antibiotic resistance.

L'utilisation croissante d'antibiotiques et l'augmentation de la résistance bactérienne aux antibiotiques constituent un défi pour le développement et la santé mondiaux. Il est nécessaire de communiquer et de diffuser les initiatives qui parviennent à contenir ce problème. En Suède, la propagation rapide de pneumocoques résistants dans le sud du pays en 1995 a conduit à la formation du Programme stratégique suédois contre la résistance aux antibiotiques, également connu sous le nom de Strama. La création de ce programme a été un point de départ important pour coordonner des efforts sur le long terme afin de lutter contre la résistance aux antibiotiques dans le pays. Cet article décrit les principales stratégies du programme: engagement aux niveaux local et national; suivi de l'utilisation d'antibiotiques afin de prendre des décisions en connaissance de cause; objectif national de prescription d'antibiotiques; surveillance de la résistance aux antibiotiques pour agir au niveau local, national et mondial; observation des tendances de résistance; lutte contre les infections afin de limiter la progression de la résistance; communication afin d'inciter à l'action et au changement des comportements. L'adoption d'une démarche ascendante a été un élément clé pour favoriser les changements à long terme, notamment la collaboration étroite avec les prescripteurs au niveau local. Le travail qui est décrit ici et les enseignements tirés pourraient aider les pays à mettre en œuvre leur propre plan d'action national contre la résistance aux antibiotiques.

El creciente uso de antibióticos y el aumento de los niveles de resistencia bacteriana a los antibióticos son un desafío para la salud y el desarrollo mundiales. Es necesario comunicar y difundir iniciativas de éxito para contener el problema. En Suecia, una rápida propagación de neumococos resistentes en el sur del país desencadenó la formación del programa estratégico sueco contra la resistencia a los antibióticos, también conocido como Strama, en 1995. La creación del programa fue un importante punto de partida de los esfuerzos coordinados a largo plazo para combatir la resistencia a los antibióticos en el país. En este artículo se describen las principales estrategias del programa: labores dedicadas a nivel local y nacional, supervisión del uso de antibióticos para tomar decisiones fundamentadas, un objetivo nacional para las recetas de antibióticos, vigilancia de la resistencia a los antibióticos para la acción local, nacional y global; seguimiento de las tendencias de resistencia, control de las infecciones para reducir la propagación de la resistencia y comunicación para sensibilizar sobre las medidas y el cambio de comportamiento. Un elemento clave para conseguir cambios a largo plazo ha sido en enfoque ascendente, que incluye trabajar estrechamente con los médicos a nivel local. El trabajo aquí descrito y las lecciones aprendidas podrían ofrecer información a los países que implementan sus propios planes de medidas nacionales contra la resistencia a los antibióticos.

Community carriage of ESBL-producing Escherichia coli is associated with strains of low pathogenicity: a Swedish nationwide study.

OBJECTIVES: Community carriage of ESBL-producing Escherichia coli (EPE) is common worldwide and there is a need to understand the connection between carriage and infection. We compared the molecular characteristics of EPE among Swedish community carriers with those of EPE causing invasive infections. METHODS: We collected 2134 faecal samples from randomly selected Swedish inhabitants and examined them for the presence of EPE. All participating volunteers answered a questionnaire about putative risk factors for EPE carriage. Suspected EPE isolates (n = 418) from patients with bloodstream infection (BSI) were collected from Swedish laboratories. Isolates were genotypically and phenotypically characterized. RESULTS: Our results show that the EPE population found in carriers generally had lower pathogenicity compared with the isolates from BSIs, since carriers had a lower proportion of E. coli belonging to phylogroup B2, ST131 and ST131 subclone H30-Rx. Isolates from carriers also had lower levels of multiresistance. The Swedish carriage rate of EPE was 4.7% (101/2134) among healthy volunteers. Risk factors associated with carriage were travel to countries in Asia (OR = 3.6, 95% CI = 1.4-9.2) and Africa (OR = 3.6, 95% CI = 1.7-7.7) and a diet without pork (OR = 0.5, 95% CI = 0.3-0.8 for pork eaters). CONCLUSIONS: E. coli host factors previously associated with higher pathogenicity were all more common in BSIs compared with carriers. This indicates that the risk of invasive infection with EPE may be relatively modest in many community carriers and that EPE carriage of high-risk strains should be the focus of attention for prevention.

Limited Dissemination of Extended-Spectrum ß-Lactamase- and Plasmid-Encoded AmpC-Producing Escherichia coli from Food and Farm Animals, Sweden.

Extended-spectrum ß-lactamase (ESBL)- and plasmid-encoded ampC (pAmpC)-producing Enterobacteriaceae might spread from farm animals to humans through food. However, most studies have been limited in number of isolates tested and areas studied. We examined genetic relatedness of 716 isolates from 4,854 samples collected from humans, farm animals, and foods in Sweden to determine whether foods and farm animals might act as reservoirs and dissemination routes for ESBL/pAmpC-producing Escherichia coli. Results showed that clonal spread to humans appears unlikely. However, we found limited dissemination of genes encoding ESBL/pAmpC and plasmids carrying these genes from foods and farm animals to healthy humans and patients. Poultry and chicken meat might be a reservoir and dissemination route to humans. Although we found no evidence of clonal spread of ESBL/pAmpC-producing E. coli from farm animals or foods to humans, ESBL/pAmpC-producing E. coli with identical genes and plasmids were present in farm animals, foods, and humans.

Carbapenemase-producing Enterobacteriaceae in Sweden 2007-2013: Experiences from seven years of systematic surveillance and mandatory reporting.

Carbapenemase-producing Enterobacteriaceae (CPE) are increasing worldwide, and are a major threat to healthcare systems. Recent European data support that many countries have interregional spread of CPE or an endemic situation. In Sweden mandatory laboratory reporting of CPE of both colonisation and infection has been practiced since 2007 and since 2012 also by treating physicians. Between 2007 and 2013, 94 cases of CPE were detected in Sweden, out of which 24 were considered to cause clinical infections (bloodstream infection (n=4), urinary tract infection (n=12), wound infection (n=4), respiratory tract infection (n=2) and catheter related (n=2). The majority were detected in the hospital setting through faecal screening or as probable colonisers in clinical cultures. Travel abroad was observed in the majority of the patients (81%), and among them 84% had been hospitalised. During the study period only two chains of transmissions in Swedish hospitals were reported, involving four patients. Klebsiella pneumoniae was the primarily isolated species (n=57) followed by Escherichia coli (n=29). blaNDM was the predominant carbapenemase gene (n=36), followed by blaOXA-48-group, blaKPC and blaVIM. In 26/94 cases (28%) isolates were categorised as possible XDR (extensively drug-resistant). CPE are increasing in Sweden, but are still at a comparably low level.

Lactobacillus decelerates cervical epithelial cell cycle progression.

We investigated cell cycle progression in epithelial cervical ME-180 cells during colonization of three different Lactobacillus species utilizing live cell microscopy, bromodeoxyuridine incorporation assays, and flow cytometry. The colonization of these ME-180 cells by L. rhamnosus and L. reuteri, originating from human gastric epithelia and saliva, respectively, was shown to reduce cell cycle progression and to cause host cells to accumulate in the G1 phase of the cell cycle. The G1 phase accumulation in L. rhamnosus-colonized cells was accompanied by the up-regulation and nuclear accumulation of p21. By contrast, the vaginal isolate L. crispatus did not affect cell cycle progression. Furthermore, both the supernatants from the lactic acid-producing L. rhamnosus colonies and lactic acid added to cell culture media were able to reduce the proliferation of ME-180 cells. In this study, we reveal the diversity of the Lactobacillus species to affect host cell cycle progression and demonstrate that L. rhamnosus and L. reuteri exert anti-proliferative effects on human cervical carcinoma cells.

Neisseria gonorrhoeae infection causes DNA damage and affects the expression of p21, p27 and p53 in non-tumor epithelial cells.

The constant shedding and renewal of epithelial cells maintain the protection of epithelial barriers. Interference with the processes of host cell-cycle regulation and barrier integrity permits the bacterial pathogen Neisseria gonorrhoeae to effectively colonize and invade epithelial cells. Here, we show that a gonococcal infection causes DNA damage in human non-tumor vaginal VK2/E6E7 cells with an increase of 700 DNA strand breaks per cell per hour as detected by an alkaline DNA unwinding assay. Infected cells exhibited elevated levels of DNA double-strand breaks, as indicated by a more than 50% increase in cells expressing DNA damage-response protein 53BP1-positive foci that co-localized with phosphorylated histone H2AX (γH2AX). Furthermore, infected cells abolished their expression of the tumor protein p53 and induced an increase in the expression of cyclin-dependent kinase inhibitors p21 and p27 to 2.6-fold and 4.2-fold of controls, respectively. As shown by live-cell microscopy, flow cytometry assays, and BrdU incorporation assays, gonococcal infection slowed the host cell-cycle progression mainly by impairing progression through the G2 phase. Our findings show new cellular players that are involved in the control of the human cell cycle during gonococcal infection and the potential of bacteria to cause cellular abnormalities.

Neisseria gonorrhoeae infection induces altered amphiregulin processing and release.

Adhesion of the human pathogen Neisseria gonorrhoeae has established effects on the host cell and evokes a variety of cellular events including growth factor activation. In the present study we report that infection with N. gonorrhoeae causes altered amphiregulin processing and release in human epithelial cells. Amphiregulin is a well-studied growth factor with functions in various cell processes and is upregulated in different forms cancer and proliferative diseases. The protein is prototypically cleaved on the cell surface in response to external stimuli. We demonstrate that upon infection, a massive upregulation of amphiregulin mRNA is seen. The protein changes its subcellular distribution and is also alternatively cleaved at the plasma membrane, which results in augmented release of an infection-specific 36 kDa amphiregulin product from the surface of human cervical epithelial cells. Further, using antibodies directed against different domains of the protein we could determine the impact of infection on pro-peptide processing. In summary, we present data showing that the infection of N. gonorrhoeae causes an alternative amphiregulin processing, subcellular distribution and release in human epithelial cervical cells that likely contribute to the predisposition cellular abnormalities and anti-apoptotic features of N. gonorrhoeae infections.

Long-term impacts of antibiotic exposure on the human intestinal microbiota.

Although it is known that antibiotics have short-term impacts on the human microbiome, recent evidence demonstrates that the impacts of some antibiotics remain for extended periods of time. In addition, antibiotic-resistant strains can persist in the human host environment in the absence of selective pressure. Both molecular- and cultivation-based approaches have revealed ecological disturbances in the microbiota after antibiotic administration, in particular for specific members of the bacterial community that are susceptible or alternatively resistant to the antibiotic in question. A disturbing consequence of antibiotic treatment has been the long-term persistence of antibiotic resistance genes, for example in the human gut. These data warrant use of prudence in the administration of antibiotics that could aggravate the growing battle with emerging antibiotic-resistant pathogenic strains.

Metronidazole is still the drug of choice for treatment of anaerobic infections.

Metronidazole has been used for the treatment of infections for >45 years and is still successfully used for the treatment of trichomoniasis, amoebiasis, and giardiasis. Anaerobic bacterial infections caused by Bacteroides species, fusobacteria, and clostridia respond favorably to metronidazole therapy. Good clinical results in the treatment of vaginosis due to Gardnerella vaginalis have also been reported. Rates of resistance to metronidazole are still generally low; however, several studies have reported decreased susceptibility among Bacteroides species, as well as different mechanisms of resistance. Metronidazole-resistant Helicobacter pylori strains have been described, but combination therapy (eg, metronidazole, amoxicillin, or clarithromycin plus omeprazole) is still recommended for eradication of this pathogen in patients with gastroduodenal ulcers. Metronidazole is considered to be a cost-effective drug because of its low cost, good activity against pathogenic anaerobic bacteria, favorable pharmacokinetic and pharmacodynamic properties, and minor adverse effects. Metronidazole is still the criterion standard for therapy of anaerobic infections, as was described by Tally and colleagues 35 years ago.

Prolonged impact of a one-week course of clindamycin on Enterococcus spp. in human normal microbiota.

Human intestinal Enterococcus spp. was monitored during a 2-y period after 7 d clindamycin treatment. Consecutive faecal samples were collected from 8 healthy volunteers, 4 of whom had received clindamycin. After treatment, the number of enterococcal colonies was diminished and species variation extended. Erythromycin and clindamycin resistance increased from 19% to 69% and 0% to 67%, respectively. Elevated resistance levels lasted up to 9 months and erm(B) was detected in samples up to 6 months. Our results show that the clindamycin treatment had a prolonged impact on resistance and species variation.

Restored fitness leads to long-term persistence of resistant Bacteroides strains in the human intestine.

Acquired antibiotic resistance typically confers a cost to the bacteria, but these costs can be reduced by genetic compensation over time. The fitness of two Bacteroides thetaiotaomicron clones consecutively isolated in vivo was studied using an in vitro pair-wise competition method. The isolates derived from faecal samples of two clindamycin-exposed healthy volunteers and the two B. thetaiotaomicron clone types could be followed up to 18 months in these two subjects. The two clones were originally susceptible to clindamycin and lacked erm genes; however, after 7 days of clindamycin administration they carried the erm (erythromycin methylase)(G) or (F) gene, respectively, and expressed phenotypic clindamycin resistance. The initial cost of acquired resistance was high as seen in the in vitro pair-wise competition experiments. At 2 weeks post-administration, no growth disadvantage was detected for isolates of either of the two clones in the in vitro experiments and this regained fitness remained for isolates collected up to 18 months. Competition analysis of an in vitro isolated erm(G) positive transconjugant also demonstrated an initial reduction of fitness that was restored over time. The results indicate that the biological cost associated with a resistance gene can rapidly be compensated during in vivo growth. Thus, once the resistant clone has gained its resistance determinant it will be difficult to eliminate.

Long-term ecological impacts of antibiotic administration on the human intestinal microbiota.

Antibiotic administration is known to cause short-term disturbances in the microbiota of the human gastrointestinal tract, but the potential long-term consequences have not been well studied. The aims of this study were to analyse the long-term impact of a 7-day clindamycin treatment on the faecal microbiota and to simultaneously monitor the ecological stability of the microbiota in a control group as a baseline for reference. Faecal samples from four clindamycin-exposed and four control subjects were collected at nine different time points over 2 years. Using a polyphasic approach, we observed highly significant disturbances in the bacterial community that persisted throughout the sampling period. In particular, a sharp decline in the clonal diversity of Bacteroides isolates, as assessed by repetitive sequence-based PCR (rep-PCR) and long-term persistence of highly resistant clones were found as a direct response to the antibiotic exposure. The Bacteroides community never returned to its original composition during the study period as assessed using the molecular fingerprinting technique, terminal restriction fragment length polymorphism (T-RFLP). Furthermore, using real-time PCR we found a dramatic and persistent increase in levels of specific resistance genes in DNA extracted from the faeces after clindamycin administration. The temporal variations in the microbiota of the control group were minor compared to the large and persistent shift seen in the exposed group. These results demonstrate that long after the selection pressure from a short antibiotic exposure has been removed, there are still persistent long term impacts on the human intestinal microbiota that remain for up to 2 years post-treatment.

Long-term antimicrobial resistance in Escherichia coli from human intestinal microbiota after administration of clindamycin.

The aim of this study was to gain better knowledge of how the intestinal microbiota are affected over time after administration of an antimicrobial agent. This study monitored the prevalence and frequencies of antibiotic resistance in Enterobacteriaceae against 17 antimicrobial agents, during a 2-y period, in consecutive faecal samples collected from 8 healthy volunteers. Four subjects had received 150 mg clindamycin perorally for 7 d, while 4 non-exposed subjects served as a control group. The samples from both groups were cultured and screened for Enterobacteriaceae. The highest incidence of resistance observed was to ampicillin. The ampicillin resistance is due to production of the beta-lactamase TEM-1. The administration of clindamycin had a prolonged impact on the composition of the microbiota, even though enterobacteria are intrinsically resistant to clindamycin; the level of resistance in Escherichia coli isolates was elevated after administration and persisted up to 9 months after administration. After 9 months the susceptibility levels in the exposed group were similar to those at d 0.