Model Systems of Human Intestinal Flora, to Set Acceptable Daily Intakes of Antimicrobial Residues

The veterinary use of antimicrobial drugs in food producing animals may result in residues in food, that might modify the consumer gut flora. This review compares three model systems that maintain a complex flora of human origin: (i) human flora associated (HFA) continuous flow cultures in chemostats, (ii) HFA mice, and (iii) human volunteers. The "No Microbial Effect Level" of an antibiotic on human flora, measured in one of these models, is used to set the accept¬able daily intake (ADI) for human consumers. Human volunteers trials are most relevant to set microbio¬log¬ical ADI, and may be considered as the "gold standard". However, human trials are very expensive and unethical. HFA chemostats are controlled systems, but tetracycline ADI calculated from a chemostat study is far above result of a human study. HFA mice studies are less expensive and better controlled than human trials. The tetracycline ADI derived from HFA mice studies is close to the ADI directly obtained in human volunteers

Antibacterial prophylaxis of surgical site infections in oral surgery: not only and not always systemic antibiotics

Antibacterial prophylaxis is a set of treatment measures, including antibiotic prophylaxis, under surgeon’s responsibility. If local measures are always to be applied, antibiotic prophylaxis administration needs a careful case selection in order to avoid indiscriminate prescription. Local measures include the following: use of sterile instrumentation and special devices to prevent surgical site contamination; good surgical treatment; pre-surgical treatment of acute local infections; pre-surgical calculus removal and perioperative plaque control; post-surgical follow-up. Antibiotic prophylaxis should follow the following five basic principles: only procedures that have high risk of infection need antibiotic prophylaxis; an adequate antibiotic should be chosen; a high dose of antibiotic should be used; the time of administration should be correct; antibiotic activity should be as short as possible

Antibiotic stewardship for staff nurses: Five Key Ways you Influence Antibiotic Use

Over the past decade, antibiotic resistance has increased and spread dramatically throughout the world. According to the Centers for Disease Control and Prevention (CDC), antibiotic use is the single most important factor leading to antibiotic resistance. The CDC estimates that every year, 2 million Americans develop serious infections involving bacteria that resist one or more antibiotics, and these infections kill at least 23,000 each year. Antibiotic prescribing in U.S. acute-care hospitals is common— and often unwarranted. A 2014 study found that up to half of hospitalized patients received at least one antibiotic and in 30% to 50% of these cases, antibiotics were unnecessary or inappropriate. Such antibiotic misuse contributes to the emergence and spread of antibioticresistant organisms, such as methicillin- resistant Staphylococcus aureus and vancomycin-resistant enterococci. (See Unheeded warnings.) If you’re a staff nurse, you’ve probably witnessed firsthand the consequences of inappropriate antibiotic use, ranging from development of Clostridium difficile (a well-recognized cause of healthcare- associated infectious diarrhea) to fatal infections with multidrugresistant pathogens against which no effective antibiotic therapy exists. What’s more, antibiotic-resistant infections add considerably to medical costs, with estimates as high as $35 billion a year

Social interaction, noise and antibiotic-mediated switches in the intestinal microbiota

The intestinal microbiota plays important roles in digestion and resistance against entero-pathogens. As with other ecosystems, its species composition is resilient against small disturbances but strong perturbations such as antibiotics can affect the consortium dramatically. Antibiotic cessation does not necessarily restore pre-treatment conditions and disturbed microbiota are often susceptible to pathogen invasion. Here we propose a mathematical model to explain how antibiotic-mediated switches in the microbiota composition can result from simple social interactions between antibiotic-tolerant and antibiotic-sensitive bacterial groups. We build a two-species (e.g. two functional-groups) model and identify regions of domination by antibiotic-sensitive or antibiotic-tolerant bacteria, as well as a region of multistability where domination by either group is possible. Using a new framework that we derived from statistical physics, we calculate the duration of each microbiota composition state. This is shown to depend on the balance between random fluctuations in the bacterial densities and the strength of microbial interactions. The singular value decomposition of recent metagenomic data confirms our assumption of grouping microbes as antibiotic-tolerant or antibiotic-sensitive in response to a single antibiotic. Our methodology can be extended to multiple bacterial groups and thus it provides an ecological formalism to help interpret the present surge in microbiome data.Comment: 20 pages, 5 figures accepted for publication in Plos Comp Bio. Supplementary video and information availabl

The impact of antibiotic use on transmission of resistant bacteria in hospitals: Insights from an agent-based model

Extensive antibiotic use over the years has led to the emergence and spread of antibiotic resistant bacteria (ARB). Antibiotic resistance poses a major threat to public health since for many infections antibiotic treatment is no longer effective. Hospitals are focal points for ARB spread. Antibiotic use in hospitals exerts selective pressure, accelerating the spread of ARB. We used an agent-based model to explore the impact of antibiotics on the transmission dynamics and to examine the potential of stewardship interventions in limiting ARB spread in a hospital. Agents in the model consist of patients and health care workers (HCW). The transmission of ARB occurs through contacts between patients and HCW and between adjacent patients. In the model, antibiotic use affects the risk of transmission by increasing the vulnerability of susceptible patients and the contagiousness of colonized patients who are treated with antibiotics. The model shows that increasing the proportion of patients receiving antibiotics increases the rate of acquisition non-linearly. The effect of antibiotics on the spread of resistance depends on characteristics of the antibiotic agent and the density of antibiotic use. Antibiotic's impact on the spread increases when the bacterial strain is more transmissible, and decreases as resistance prevalence rises. The individual risk for acquiring ARB increases in parallel with antibiotic density both for patients treated and not treated with antibiotics. Antibiotic treatment in the hospital setting plays an important role in determining the spread of resistance. Interventions to limit antibiotic use have the potential to reduce the spread of resistance, mainly by choosing an agent with a favorable profile in terms of its impact on patient's vulnerability and contagiousness. Methods to measure these impacts of antibiotics should be developed, standardized, and incorporated into drug development programs and approval packages

Clinicians’ adherence to local antibiotic guidelines for upper respiratory tract infections in the ear, nose & throat casualty department of a public general hospital

Background: In Malta, resistance to antibiotics constitutes a major threat to public health. This study aims to assess clinicians’ adherence to local antibiotic guidelines when treating cases of acute otitis media, acute tonsillitis and rhinosinusitis, that present to the ear, nose and throat (ENT) casualty department in Malta’s public general hospital, as well as to recommend methods for improving adherence and minimising overprescribing. Methodology: Data on first line antibiotic prescribing regimens was retrieved from ENT casualty sheets between February and March 2015 for adult patients (>12years) diagnosed with acute otitis media, acute tonsillitis and persistent rhinosinusitis. On an audit form, aspects of the prescribed antibiotic were benchmarked to local infection control antibiotic guidelines of 2011 to evaluate adherence. Results: From 1010 casualty records, 188 were antibiotic prescriptions, of which 93 (49.4%) were correctly indicated as per guidelines. From the indicated prescriptions 81 (87%) were assessable, out of which full adherence was only observed in 6 (7%) of prescriptions. All of these were for rhinosinusitis. Full adherence in rhinosinusitis was found to be 43%, whilst no adherence was found in the other infections. The most prescribed antibacterial for all three infections was co-amoxiclav. Conclusion: The current antibiotic guidelines have not been adequately implemented as adherence to antibiotic choice alone was low in all infections. This may have an impact on antibiotic-resistant rates and infection incident rates. Hence to improve adherence to local antibiotic guidelines, it is recommended that these should be clear, regularly updated, well disseminated and reinforced. The addition of a care pathway may further improve appropriate antibiotic use.peer-reviewe