Development Of Antimicrobial Resistance In Bacteria Research Articles

Safety evaluation of the food enzyme subtilisin from the non-genetically modified Bacillus paralicheniformis strain AP-01.

The food enzyme subtilisin (EC 3.4.21.62) is produced with the non-genetically modified Bacillus paralicheniformis strain AP-01 by Nagase (Europa) GmbH. It was considered free from viable cells of the production organism. The food enzyme is intended to be used in five food manufacturing processes. Since residual amounts of food enzyme-total organic solids (TOS) are removed in one process, dietary exposure was calculated only for the remaining four food manufacturing processes. It was estimated to be up to 0.875 mg TOS/kg body weight per day in European populations. The production strain of the food enzyme has the capacity to produce bacitracin and thus failed to meet the requirements of the Qualified Presumption of Safety approach. Bacitracin was detected in the industrial fermentation medium but not in the food enzyme itself. However, the limit of detection of the analytical method used for bacitracin was not sufficient to exclude the possible presence of bacitracin at a level representing a risk for the development of antimicrobial resistant bacteria. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and twenty-eight matches with respiratory allergens, one match with a contact allergen and two matches with food allergens (melon and pomegranate) were found. The Panel considered that the risk of allergic reactions upon dietary exposure to this food enzyme, particularly in individuals sensitised to melon or pomegranate, cannot be excluded, but would not exceed the risk of consuming melon or pomegranate. Based on the data provided, the Panel could not exclude the presence of bacitracin, a medically important antimicrobial, and consequently the safety of this food enzyme could not be established.

Safety evaluation of the food enzyme subtilisin from the non-genetically modified Bacillus paralicheniformis strain DP-Dzx96.

The food enzyme subtilisin (serine endopeptidase, EC 3.4.21.62) is produced with the non-genetically modified Bacillus paralicheniformis strain DP-Dzx96 by Genencor International B.V. The food enzyme was considered free from viable cells of the production organism. The food enzyme is intended to be used in five food manufacturing processes: production of protein hydrolysates from plants and fungi, production of protein hydrolysates from meat and fish proteins, production of cooked rice, production of modified meat and fish products, and yeast processing. The production strain of the food enzyme contains known antimicrobial resistance genes. Bacitracin, a medically important antimicrobial, was detected in the food enzyme. The presence of bacitracin represents a risk for the development of antimicrobial resistant bacteria. A search for the similarity of the amino acid sequence of the food enzyme to known allergens was made and three matches with respiratory and two matches with food allergens were found. The Panel considered that, under the intended conditions of use, the risk of allergic reactions upon dietary exposure to this food enzyme, particularly in individuals sensitised to muskmelon or pomegranate, cannot be excluded, but would not exceed the risk of consuming these foods. Due to the presence of bacitracin, the Panel concluded that the food enzyme subtilisin produced with the non-genetically modified Bacillus paralicheniformis strain DP-Dzx96 cannot be considered safe.

Antimicrobial Effects of Equine Platelet Lysate.

The development of antimicrobial resistant bacteria and the lack of novel antibiotic strategies to combat those bacteria is an ever-present problem in both veterinary and human medicine. The goal of this study is to evaluate platelet lysate (PL) as a biological alternative antimicrobial product. Platelet lysate is an acellular platelet-derived product rich in growth factors and cytokines that is manufactured via plateletpheresis and pooled from donor horses. In the current study, we sought to define the antimicrobial properties of PL on select gram-positive and gram-negative bacteria. Results from an end-point in vitro assay showed that PL did not support bacterial growth, and in fact significantly reduced bacterial content compared to normal growth media. An in vitro assay was then utilized to further determine the effects on bacterial growth dynamics and showed that all strains exhibited a slower growth rate and lower yield in the presence of PL. The specific effects of PL were unique for each bacterial strain: E. coli and P. aeruginosa growth was affected in a concentration-dependent manner, such that higher amounts of PL had a greater effect, while this was not true for S. aureus or E. faecalis. Furthermore, the onset of exponential growth was delayed for E. coli and P. aeruginosa in the presence of PL, which has significant clinical implications for developing a dosing schedule. In conclusion, our findings demonstrate the potential value of PL as a broad-spectrum antimicrobial that would offer an alternative to traditional antibiotics for the treatment of bacterial infection in equine species.

Quantification and Trends of Antimicrobial Use in Commercial Broiler Chicken Production in Pakistan.

Antimicrobial resistance (AMR) is a global health challenge and antimicrobial use (AMU) in the livestock sector has been considered as one of the contributing factors towards the development of AMR in bacteria. This study summarizes the results of a point prevalence survey conducted to monitor farm-level AMU in commercial broiler chicken farms in Punjab and Khyber Pakhtunkhwa (KPK) provinces of Pakistan. A cross-sectional study was conducted to quantify AMU and to check seasonal variations of AMU in 12 commercial broiler chicken farms (six from each province) during the summer and winter seasons of the year 2020–2021. AMU was recorded using three AMU metrics: kg, mg per population correction unit (mg/PCU), and mg/kg of final flock weight. A total of 22 antimicrobial drugs (348.59 kg) were used for therapeutic or prophylactic purposes in surveyed broiler chicken farms. The total combined AMU for all the broiler chicken farms was 462.57 mg/PCU. The use of most of the antimicrobials increased during winter flocks compared to summer. The top three antimicrobial drugs used during the summer were neomycin (111.39 mg/PCU), doxycycline (91.91 mg/PCU), and tilmicosin (77.22 mg/PCU), whereas doxycycline (196.81 mg/PCU), neomycin (136.74 mg/PCU), and amoxicillin (115.04 mg/PCU) during the winter. Overall, 60% of the antibiotics used in broiler chicken were critically important antimicrobial classes (CIA) for human medicine as characterized by the World Health Organization. Our findings showed high AMU in broiler chicken production and a call for urgent actions to regulate CIA use in food animals in Pakistan. This baseline survey is critical for the design and implementation of a subsequent national level AMU surveys that can include additional farming types, animals’ species, and geographical locations over a longer period of time.

Antimicrobial Resistance of Major Bacterial Pathogens from Dairy Cows with High Somatic Cell Count and Clinical Mastitis.

Simple SummaryMastitis is the most prevalent disease of dairy cattle that causes significant economic losses. Different agents cause mastitis which leads to increased somatic cell count (SCC) and low milk quality. Treating mastitis with antimicrobials is essential to reduce SCC and improve milk quality. Excessive use or misuse of antimicrobials in dairy farms leads to the development of antimicrobial resistant bacteria. The objectives of this study were (1) to isolate and identify the causative agent of mastitis and (2) determine antimicrobial resistance profiles of bacterial isolates. A total of 174 quarter milk samples from 151 cows with high SCC and clinical mastitis from 34 dairy farms in Tennessee, Kentucky, and Mississippi were collected. Bacterial causative agents were determined by bacteriological and biochemical tests. Antimicrobial resistance of bacterial isolates against 10 commonly used antimicrobials was tested. A total of 193 bacteria consisting of six bacterial species, which include Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, Escherichia coli, Klebsiella oxytoca and Klebsiella pneumoniae were isolated. Staphylococcus aureus was the predominant isolate. The proportion of resistant isolates was relatively higher in Gram-negatives than Gram-positives. Continuous antimicrobial resistance testing and identification of reservoirs of resistance traits in dairy farms are essential to implement proper mitigation measures.Mastitis is the most prevalent and economically important disease caused by different etiological agents, which leads to increased somatic cell count (SCC) and low milk quality. Treating mastitis cases with antimicrobials is essential to reduce SCC and improve milk quality. Non-prudent use of antimicrobials in dairy farms increased the development of antimicrobial resistant bacteria. This study’s objectives were (1) to isolate and identify etiological agents of mastitis and (2) to determine antimicrobial resistance profiles of bacterial isolates. A total of 174 quarter milk samples from 151 cows with high SCC and clinical mastitis from 34 dairy farms in Tennessee, Kentucky, and Mississippi were collected. Bacterial causative agents were determined by bacteriological and biochemical tests. The antimicrobial resistance of bacterial isolates against 10 commonly used antimicrobials was tested. A total of 193 bacteria consisting of six bacterial species, which include Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, Escherichia coli, Klebsiella oxytoca and Klebsiella pneumoniae were isolated. Staphylococcus aureus was the predominant isolate followed by Strep. spp., E. coli, and Klebsiella spp. Results of this study showed that Gram-negatives (E. coli and Klebsiella spp.) were more resistant than Gram-positives (Staph. aureus and Streptococcus spp.). Continuous antimicrobial resistance testing and identification of reservoirs of resistance traits in dairy farms are essential to implement proper mitigation measures.

Calculation of Antimicrobial Use Indicators in Beef Feedlots-Effects of Choice of Metric and Standardized Values.

The potential for antimicrobial use (AMU) to lead to the development of antimicrobial resistant bacteria is an increasingly important priority in human and veterinary medicine. Accurate AMU quantification is essential to assessing the risk of antimicrobial resistance due to AMU. The quantification of AMU in production animals can be difficult, and feedlot beef cattle present a number of unique challenges. This paper presents selected parenteral data from western Canadian beef feedlots to illustrate variations in interpretation of AMU that can arise from the use of different metrics and standards. Specific examples presented compare the number of animal daily doses calculated from a given amount of antimicrobial drug (AMD) using actual and estimated weights of cattle at exposure, dose-based to weight-based indicators representing the same amount of antimicrobial, dose-based AMU indicators using different estimated durations of effect (DOE), and AMU indicators calculated using different standard weights of cattle at exposure. Changing these factors when calculating AMU indicators can have notable influences on the results obtained. Transparency about the methods used to calculate AMU indicators is critical to ensure that comparisons of use among different populations is meaningful and accurate.

Two Regimes of Perioperative Antimicrobial Prophylaxis for Equine Castration: Clinical Findings, Acute-Phase Proteins, and Bacterial Cultures

A perioperative antibiotic for equine castration with second intention healing is controversial because the necessity is unclear and antimicrobial use promotes the selection of resistant bacteria. Information about different regimes for perioperative antimicrobial prophylaxis in equine castration is sparse. Goal of this study was to compare clinical findings, acute-phase proteins, and bacterial cultures in horses undergoing castration, treated with an intravenous single administration of penicillin G sodium (1× Pen group) or a 3-day course of daily intramuscular procaine penicillin (3× Pen group). Forty-eight stallions were castrated under general anesthesia using a closed technique, with second intention healing. Serum amyloid A (SAA) and fibrinogen were measured on days 0, 3, and 8. Body temperature, wound swelling, and drainage were recorded daily over 10 days. Bacterial swabs of the wound were taken on days 0 and 3. Scrotal swelling (P = .032), amount of drainage from the wound (P = .039), and body temperature (P = .013) on day 8 after castration were significantly higher in the 1× Pen group. The concentration of SAA and fibrinogen on day 8 was significantly higher in the 1× Pen group compared with the 3× Pen group (SAA: P = .049; fibrinogen: P = .035). β-Hemolytic Streptococcus spp. were found more frequently cultured in the 1× Pen group than in the 3× Pen group. Clinical and laboratory data indicate lower inflammatory reaction in the early postoperative period after three applications of penicillin compared with a single-administration. Further investigations evaluating the long-term outcome and potential development of antimicrobial resistant bacteria are needed.

Evidence-based policy for controlling antimicrobial resistance in the food chain in Denmark

Emergence of antimicrobial resistance (AMR) in the animal reservoir forms a risk for human health. The use of antimicrobials in animals is the major cause of development of AMR in bacteria in animals. In the 1990s, the use of antimicrobials in animals, particularly as a growth promoter, led to alarming levels of AMR in many countries. This paper analyses the emergence of AMR in Denmark in terms of contributing factors that formed fertile ground from which AMR could develop. New technologies in combination with scientific unknowns led to the unexpected development of cross-resistance and an uncertainty about transmission to and risk for humans. Conflict of interests and varying susceptibility to risk between agriculture, health and commercial stakeholders complicated intervention. In addition, unintended economic incentives from old legislation resulted in a situation where the use of antimicrobials in general was stimulated. Complications of alarming high levels of AMR in animals, and a general discontent about this situation (including with farmers and vets) demanded a solution. National surveillance in DANMAP involving all stakeholders from the farm-to-fork food chain was setup to counteract scientific unknowns and conflicts of interest; new legislation was developed; and unintended economic incentives reduced. The current analysis may help to better understand the AMR problem in general and what may be done to counteract it.

Implementation of Antibiotic Rotation Protocol Improves Antibiotic Susceptibility Profile in a Surgical Intensive Care Unit

Antibiotic rotation has been proposed as a way to potentially reduce the development of antimicrobial resistant bacteria in intensive care units. We assessed the effect of an antibiotic rotation protocol on the antibiotic susceptibility profiles of three clinically relevant gram-negative microorganisms within our surgical intensive care unit (SICU). Our SICU implemented an antibiotic rotation protocol in 2003. Four antibiotics (piperacillin/tazobactam, imipenem/cilastin, ceftazidime, and ciprofloxacin) were rotated as the primary antibiotic used to treat suspected gram-negative infections every month, with the four-drug cycle being repeated every 4 months. Antibiotic susceptibility data for three microorganisms (Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae) were collected for the year before (2002) and the year after (2004) the implementation of the rotation protocol. Changes in antimicrobial susceptibility rates were analyzed for the three microorganisms. As a comparison, a similar analysis was conducted for microorganisms isolated from our medical intensive care unit, where no antibiotic rotation protocol was implemented. Implementation of an antibiotic rotation protocol in our SICU resulted in a significant increase in the percentage of P. aeruginosa isolates sensitive to ceftazidime (67% in 2002 vs. 92% in 2004, p = 0.002) and piperacillin/tazobactam (78% in 2002 vs. 92% in 2004, p = 0.043). Isolates from the medical intensive care unit did not demonstrate an increase in antimicrobial susceptibility. In fact, the susceptibility of E. coli to piperacillin/tazobactam decreased during this time period (p = 0.047). Implementation of an antibiotic rotation protocol in our SICU resulted in overall improvement in the antibiotic susceptibility profile of gram-negative microorganisms relative to our medical intensive care unit, where such a protocol was not used.

Antimicrobial Resistance of Enteric E. coli in Beef Cattle Treated with Antibiotics

It is crucial to the future of animal agriculture that veterinarians and livestock producers understand how to treat food animals in an intensive environment, while preventing or reducing the development of antimicrobial resistant bacteria. However, little is known about the actual development and transmission of antibiotic resistant organisms within or among groups of animals. In addition, little is known about the persistence of resistant organisms or their potential impact on the food production industry. The objective of this study was to characterize the development and dissemination of antimicrobial- resistant organisms in beef cattle treated with antibiotics.