Impact of water hardness on oxytetracycline oral bioavailability in fed and fasted piglets

The vehicle of administration, feed or water, and prandial state influence the oral bioavailability of amoxicillin in piglets

Feed and water components may interact with drugs and affect their dissolution and bioavailability. The impact of the vehicle of administration (feed and water) and the prandial condition of weaner piglets on amoxicillin´s oral bioavailability was evaluated. First, amoxicillin's in vitro dissolution and stability in purified, soft, and hard water, as well as release kinetics from feed in simulated gastric and intestinal media were assessed. Then, pharmacokinetic parameters and bioavailability were determined in fasted and fed pigs using soft water, hard water, or feed as vehicles of administration following a balanced incomplete block design. Amoxicillin showed similar dissolution profiles in soft and hard water, distinct from the dissolution profile obtained with purified water. Complete dissolution was only achieved in purified water, and merely reached 50% in soft or hard water. Once dissolved, antibiotic concentrations decreased by around 20% after 24 h in all solutions. Korsmeyer-Peppas model best described amoxicillin release from feed in simulated gastric and intestinal media. Feed considerably reduced antibiotic dissolution in both simulated media. In vivo, amoxicillin exhibited significantly higher bioavailability when delivered via water to fasted than to fed animals, while in-feed administration yielded the lowest values. All treatments showed a similar rate of drug absorption. In conclusion, we demonstrated that water and feed components, as well as feed present in gastrointestinal tract of piglets decrease amoxicillin´s oral bioavailability. Therefore, the use of oral amoxicillin as a broad-spectrum antibiotic to treat systemic infections in pigs should be thoroughly revised.

Knowledge, attitudes and practices of government animal health workers on antibiotic use and antibiotic resistance in Timor-Leste

Introduction

Antibiotic resistance is a global health threat, and there is growing concern on the inappropriate use of antibiotics in the livestock sector especially in low and middle income countries. The purpose of the study was to understand the knowledge, attitudes and practices on antibiotic use and antibiotic resistance of government animal health workers in Timor-Leste.

Method

A cross-sectional survey using a census approach was conducted between August 2021 and January 2022 focusing on government animal health workers involved in field work and access to antibiotics. Interviews were face-to-face in the local Tetun language. Descriptive and regression analysis informed by causal diagrams were performed.

Result

The study found poor knowledge of antibiotics among participants, with only 8.0% (13/162) able to correctly answer questions on how antibiotics worked. Knowledge of antibiotic resistance was poor as only 29.0% (47/162) of participants had heard of antibiotic resistance and were able to accurately identify that it made antibiotics less effective. Knowledge of antibiotics and knowledge of antibiotic resistance were crudely associated with being a veterinary technician and having university education. Attitude scores were positively influenced by knowledge of antibiotics and antibiotic resistance. Antibiotics were most commonly used in pigs, cattle and buffalo, with oxytetracycline being the most commonly used antibiotics in pigs and chicken. However, most participants reported a lack in supply of this antibiotic (137/162, 78.4%) and other antibiotics. Empiric use of antibiotics in sick animals was common, and some participants used antibiotics for parasitic diseases. Less than a fifth of participants reported ever using human antibiotics, and use of antibiotics for growth promotion was uncommon.

Conclusion

There is a need to develop Timor-Leste specific treatment guidelines, strengthen veterinary diagnostic support, improve antibiotic procurement, and develop training programs to address knowledge gaps and poor practices found in this study.

The Effects of Feed Intake and Water Hardness on Fluralaner Pharmacokinetics in Layer Chickens

Background

Fluralaner is a novel drug belonging to the isoxazoline class that acts on external parasites of domestic animals. It is used systemically via drinking water, especially against red poultry mite in layer chickens. Fluralaner is frequently used in layers infected with D. gallinae. However, no study to date has investigated the effects of feed intake and water hardness.

Objectives

This study aimed to investigate the effects of variable water hardness and feed intake on the pharmacokinetic profile of fluralaner.

Methods

Layer chickens were divided into four groups (n = 8): fed + purified water (Group 1), feed restricted + purified water (Group 2), feed restricted + hard water (Group 3), and feed restricted + soft water (Group 4). After administering a single dose of the drug with drinking water, the blood samples were collected for 21 days. Fluralaner concentrations in plasma samples were determined by liquid chromatography/tandem mass spectrometry. The maximum plasma concentration (C_max), time to reach maximum plasma concentration (t_max), area under the concentration–time curve values (AUC_0-21d), half-life (t_1/2), and other pharmacokinetic parameters were calculated.

Results

Although the highest maximum plasma concentration (C_max) was determined in Group 1 (fed + purified water), no statistically significant difference was found in the C_max, t_max, t_1/2, MRT_{0-inf_obs}, Vz/F_obs, and Cl/F_{_obs} parameters between the experimental groups.

Conclusions

It was concluded that the feed intake or water hardness did not change the pharmacokinetic profile of fluralaner in layer chickens. Therefore, fluralaner could be used before or after feeding with the varying water hardness in poultry industry.

Balantidium coli in pig farms suspected of porcine circovirus type 2 (PCV2) associated enteritis

Introduction

Diarrhoea in growing-finishing pigs is a common problem of commercial pig farms. Among many causative factors, porcine circovirus type 2 (PCV2) is one considered an important pathogen in modern pig production. The aim of the study was to verify if PCV2 was responsible for antibiotic non-responsive diarrhoea and wasting in pigs.

Material and Methods

A total of 13 dead pigs aged between 12 and 15 weeks from three Polish farms with persistent herd symptoms suggestive of PCV2 infection were provided for evaluation. Sections of lymph nodes and intestines were analysed by in situ hybridization (ISH) for PCV2 and histopathological examination. Faeces and intestinal scrapings were tested for Lawsonia intracellularis and Brachyspira hyodysenteriae by real-time PCR and for parasitic infection by flotation and decantation.

Results

ISH and histopathological examination showed that all pigs were PCV2 systemic disease negative. Swine dysentery was confirmed by real-time PCR on two farms, and proliferative enteropathy on one farm. In histological examinations, erosions of the caecal and colonic mucosa were found, together with cysts and trophozoites of Balantidium coli. The protozoa were present in the intestinal lumen and mucosa. B. coli cysts were identified in faeces from all examined pigs.

Conclusion

These results suggest that monitoring of B. coli infections should be an additional measure of control and prevention of gastrointestinal tract disorders in modern swine husbandry.

Maximum levels of cross-contamination for 24 antimicrobial active substances in non-target feed. Part 12: Tetracyclines: tetracycline, chlortetracycline, oxytetracycline, and doxycycline

The specific concentrations of tetracycline, chlortetracycline, oxytetracycline and doxycycline in non-target feed for food-producing animals, below which there would not be an effect on the emergence of, and/or selection for, resistance in bacteria relevant for human and animal health, as well as the specific antimicrobial concentrations in feed which have an effect in terms of growth promotion/increased yield were assessed by EFSA in collaboration with EMA. Details of the methodology used for this assessment, associated data gaps and uncertainties are presented in a separate document. To address antimicrobial resistance, the Feed Antimicrobial Resistance Selection Concentration (FARSC) model developed specifically for the assessment was applied. The FARSC for these four tetracyclines was estimated. To address growth promotion, data from scientific publications obtained from an extensive literature review were used. Levels in feed that showed to have an effect on growth promotion/increased yield were reported for tetracycline, chlortetracycline, oxytetracycline, whilst for doxycycline no suitable data for the assessment were available. Uncertainties and data gaps associated with the levels reported were addressed. It was recommended to perform further studies to supply more diverse and complete data related to the requirements for calculation of the FARSC for these antimicrobials.

Removal of antimicrobial prophylaxis and its effect on swine carriage of antimicrobial-resistant coliforms

The use of antimicrobials in the food animal industry has caused an increased prevalence of antimicrobial-resistant bacteria and antimicrobial resistance genes, which can be transferred to the microbiota of humans through the food chain or the environment. To reduce the development and spread of antimicrobial resistance, restrictions on antimicrobial use in food animals have been implemented in different countries. We investigated the impact of an antimicrobial restriction intervention during two generations of pigs. Fecal samples were collected in five growth phases. The frequency of antimicrobial-resistant coliforms and antimicrobial-resistant bacteria or antimicrobial resistance genes was analyzed. No differences in the richness or abundance of antimicrobial-resistant coliforms or antimicrobial resistance genes were found when animals fed with or without prophylactic antimicrobials were compared. Withholding antimicrobial supplementation did not negatively affect weight gain in pigs. Withdrawal of prophylactic antimicrobial consumption during two generations of pigs was not enough to reduce the prevalence of antimicrobial resistance genes, as measured by richness and abundance markers. This study indicates that the fitness costs associated with bacterial carriage of some antimicrobial resistance genes are low.

Potential interactions between an oral fosfomycin formulation and feed or drinking water: Impact on bioavailability in piglets

Feed and drinking water are the most frequently used vehicles for administration of antibiotics in intensive pig production. Interactions of drugs with feed and water components may affect dissolution and bioavailability. Therefore, antibiotic formulations should be tested in order to assure their suitability for oral use. In this study, an oral fosfomycin (FOS) formulation was evaluated considering dissolution in water (soft and hard), release kinetics from feed in simulated gastrointestinal fluids and bioavailability after oral administration blended into feed or dissolved in water (soft and hard), to fed and fasted piglets. FOS reached immediate dissolution in soft and hard water. The presence of feed significantly decreased antibiotic dissolution in simulated intestinal medium. Bioavailability was lower when feed was used as a vehicle for FOS administration than when the drug was dissolved in water (soft or hard). The fed or fasted condition of piglets did not affect bioavailability. Probably, FOS interactions with feed components alter its dissolution in the gastrointestinal tract, and only a fraction of the dose would be available for absorption. This information must be considered to support decisions on eligibility of antibiotic pharmaceutical formulations and the vehicle for their administration in order to pursue a responsible use of antibiotics.

The Spatiotemporal Patterns of Climate Asymmetric Warming and Vegetation Activities in an Arid and Semiarid Region

Asymmetric warming was bound to have a major impact on terrestrial ecosystems in arid regions during global warming. Further study was necessary to reveal the spatiotemporal patterns of asymmetric warming in Xinjiang; this study analyzed the climate and normalized difference vegetation index (NDVI) data (2000–2020). The change trends of the day and nighttime warming (DNW), seasonal warming, and the diurnal temperature range in northern Xinjiang (S1) and southern Xinjiang (S2) were determined. The findings indicated that the DNW rate showed a significant (p < 0.05) upward trend, especially in winter. The nighttime warming rate (0.65 °C (decade)−1) was faster than the daytime warming rate (0.4 °C (decade)−1), and the diurnal temperature range between daytime and nighttime exhibited a decreasing trend. The diurnal temperature range was the highest in spring and the lowest in winter. Extreme values of the diurnal temperature range appeared in autumn (48.6 °C) and winter (12.3 °C) and both in S1. The Tmin in S1 had an abruption trend in 2006–2017, the Tmax in S2 had an abruption trend in 2005–2011, and the probability of spatial abruption in S1 was higher than that in S2. The partial correlation between the NDVI and Tmin was significantly higher than that between the NDVI and Tmax in the area where the significance test passed; therefore, asymmetric nighttime warming had a greater impact on the NDVI than the asymmetric daytime warming.

Impact of water hardness on oxytetracycline oral bioavailability in fed and fasted piglets

Water hardness is a critical factor that affects oxytetracycline dissolution by chelation with cations. These interactions may lead to impaired dosing and consequently decrease absorption. Moreover, feed present in gastrointestinal tract may interact with antibiotic and alter pharmacokinetic parameters. In the present study, dissolution profiles of an oxytetracycline veterinary formulation were assessed in purified, soft and hard water. Furthermore, oxytetracycline absolute bioavailability, after oral administration of the drug dissolved in soft or hard water, was evaluated in fed and fasted piglets. A maximum dissolution of 86% and 80% was obtained in soft and hard water, respectively, while in purified water dissolution was complete. Results from in vivo study reconfirmed oxytetracycline's very low oral bioavailability. The greatest values were attained when antibiotic was dissolved in soft water and in fasted animals. Statistically significant lower absolute bioavailability was achieved when hard water was used and/or animals were fed. Moreover, Cmax attained in all treatments was lower than MIC90 of most important swine pathogens. For these reasons, the oral use of OTC formulations, that have demonstrated low oral bioavailability, should be avoided to treat systemic diseases in pigs.

In the present study, dissolution profiles of an oxytetracycline veterinary formulation were assessed in purified, soft and hard water. Furthermore, oxytetracycline absolute bioavailability, after oral administration of the drug dissolved in soft or hard water, was evaluated in fed and fasted piglets. A maximum dissolution of 86% and 80% was obtained in soft and hard water respectively, while in purified water dissolution was complete. Results from in vivo study reconfirmed oxytetracycline's very low oral bioavailability, the lowest value statistically significant was achieved when hard water was used and/or fed animals. The use of low oral bioavailability antibiotics represents a risk factor that might lead to therapeutic failure and antimicrobial resistance, for these reasons the oral use of oxytetracycline to treat systemic diseases in pig production should be avoided.