Adverse Effect of Antibiotics Administration on Horse Health: An Overview

A comparative study evaluating three line immunoassays available for serodiagnosis of equine Lyme borreliosis: Detection of Borrelia burgdorferi sensu lato-specific antibodies in serum samples of vaccinated and non-vaccinated horses

Diagnosis of equine Lyme borreliosis (LB), an infection caused by members of the Borrelia burgdorferi sensu lato complex (Bbsl), is challenging due to the nonspecific clinical signs of the disease and due to the variety of non-standardized serological tests. Specific vaccine-induced antibodies against LB, providing an effective protection against the infection, complicate the issue further. The standard for the detection of specific antibodies against Bbsl is a two-tier test system based on an enzyme-linked immunosorbent assay (ELISA) or indirect fluorescent antibody test (IFA) for antibody screening combined with a qualitative, highly specific immunoassay (e. g. line immunoassay (LIA)) for confirmation. In this study, three LIAs available for detection of antibodies in equine serum samples were evaluated and compared. A total of 393 serum samples of 131 horses with known serostatus were used. It included groups of non-vaccinated horses, immunized horses (vaccinations against LB on days 0 and 14), and horses that had received an initial immunization plus an additional booster on day 180. Sera were collected on days 0, 135 and 210 of the study. Results were compared considering the tests' sensitivity, specificity, diagnostic outcome, and the operability of each test. Agreements of the diagnostic results among the LIAs were calculated for overall test results and single antigen-antibody-complex signal results. They are presented as inter-rater agreement and statistic reliability, represented by the Fleiss' kappa coefficient. Agreement scores ranged from poor to moderate depending on group and time-point of blood sample collection. Depending on LIA used, deficiencies were observed in the form of non-sufficient sensitivity of antigen signals on the LIA strips (especially for outer surface protein A (OspA) or variable major protein like sequence expressed (VlsE)) or as an inappropriate test interpretation of the OspA signal. Operability of the three LIAs was equally user-friendly with minor variations. In two LIAs, test-evaluation was simplified by a supplied scanner and evaluation software. To improve functionality of available LIAs for equine serum samples it is advisable to adjust sensitivity and specificity of single test antigen signals and establish appropriate evaluation protocols.

Treatment approaches to horses with acute diarrhea admitted to referral institutions: A multicenter retrospective study

BACKGROUND

This study aimed to describe and compare therapeutic approaches for horses with acute diarrhea in different geographic regions worldwide.

METHODS

Clinical information was retrospectively collected from diarrheic horses presented to participating institutions between 2016 and 2020, including fluid therapy on admission, antimicrobial drugs, probiotics, anti-endotoxic medications, anti-inflammatory drugs, gastroprotectants, digital cryotherapy, and toxin-binding agents. Seasonal and geographic differences were investigated.

RESULTS

1438 horses from 26 participating hospitals from 5 continents were included. On admission, 65% (926/1419) of horses were administered a fluid bolus. Antimicrobial drugs were administered to 55% (792/1419) within the first 24 hours of admission, with penicillin and gentamicin being the most used combination (25%, 198/792). Horses with leukopenia (OR: 2.264, 95%CI: 1.754 to 2.921; P<0.001) or meeting systemic inflammatory response syndrome criteria (OR: 2.542, 95%CI: 1.919 to 3.368; P<0.001) had higher odds of being administered antimicrobial drugs. Other treatments administered included probiotics (15%, 215/1438), polymyxin B (13%; 187/1438), pentoxifylline (8%; 118/1438), gastroprotectants (44%; 626/1419), digital cryotherapy (34%; 489/1435), plasma transfusion (13%; 182/1410) and toxin-binding agents (36%; 515/1438).

LIMITATIONS

Due to the retrospective nature of the study, the rationale for treatment decisions was unavailable, and associations with survival could not be evaluated.

CONCLUSIONS

Treatments varied between hospitals from different geographic regions. Prospective clinical trials are required to evaluate the effects of various treatments on survival.

Antimicrobial Resistance in Equines: A Growing Threat to Horse Health and Beyond-A Comprehensive Review

The equine industry holds substantial economic importance not only in the USA but worldwide. The occurrence of various infectious bacterial diseases in horses can lead to severe health issues, economic losses, and restrictions on horse movement and trade. Effective management and control of these diseases are therefore crucial for the growth and sustainability of the equine industry. While antibiotics constitute the primary treatment strategy for any bacterial infections in horses, developing resistance to clinically important antibiotics poses significant challenges to equine health and welfare. The adverse effects of antimicrobial overuse and the escalating threat of resistance underscore the critical importance of antimicrobial stewardship within the equine industry. There is limited information on the epidemiology of antimicrobial-resistant bacterial infections in horses. In this comprehensive review, we focus on the history and types of antimicrobials used in horses and provide recommendations for combating drug-resistant bacterial infections in horses. This review also highlights the epidemiology of antimicrobial resistance (AMR) in horses, emphasizing the public health significance and transmission dynamics between horses and other animals within a One Health framework. By fostering responsible practices and innovative control measures, we can better help the equine industry combat the pressing threat of AMR and thus safeguard equine as well as public health.

Design and optimization of piperidine-substituted thiophene[3,2-d]pyrimidine-based HIV-1 NNRTIs with improved drug resistance and pharmacokinetic profiles

HIV-1 reverse transcriptase (RT) has received great attention as an attractive therapeutic target for acquired immune deficiency syndrome (AIDS), but the inevitable drug resistance and side effects have always been major challenges faced by non-nucleoside reverse transcriptase inhibitors (NNRTIs). This work aimed to identify novel chemotypes of anti-HIV-1 agents with improved drug-resistance profiles, reduced toxicity, and excellent druggability. A series of diarylpyrimidine (DAPY) derivatives were prepared via structural modifications of the leads K-5a2 and 25a. Among them, 15a with dimethylphosphine oxide moiety showed the most prominent antiviral potency against all of the tested viral panel, being 1.6-fold (WT, EC50 = 1.75 nmol/L), 3.0-fold (L100I, EC50 = 2.84 nmol/L), 2.4-fold (K103N, EC50 = 1.27 nmol/L), 3.3-fold (Y181C, EC50 = 5.38 nmol/L), 2.9-fold (Y188L, EC50 = 7.96 nmol/L), 2.5-fold (E138K, EC50 = 4.28 nmol/L), 4.8-fold (F227L/V106A, EC50 = 3.76 nmol/L) and 5.3-fold (RES056, EC50 = 15.8 nmol/L) more effective than that of the marketed drug ETR. Molecular docking results illustrated the detailed interactions formed by compound 15a and WT, F227L/V106A, and RES056 RT. Moreover, 15a·HCl carried outstanding pharmacokinetic (t 1/2 = 1.32 h, F = 40.8%) and safety profiles (LD50 > 2000 mg/kg), which demonstrated that 15a HCl is a potential anti-HIV-1 drug candidate.

Insights into the pH-dependent interactions of sulfadiazine antibiotic with soil particle models

Sulfonamide antibiotics (SAs) are widely used as a broad-spectrum antibiotic, leading to global concerns due to their potential soil accumulation and subsequent effects on ecosystems. SAs often exhibit remarkable environmental persistence, necessitating further investigation to uncover the ultimate destiny of these molecules. In this work, molecular dynamics simulations combined with complementary quantum chemistry calculations were employed to investigate the influence of pH on the behavior of sulfadiazine (SDZ, a typical SAs) in soil particle models (silica, one of the main components of soil). Meanwhile, the quantification of SDZ molecules aggregation potential onto silica was further extended. SDZ molecules tend to form a monolayer on the soil surface under acidic conditions while forming aggregated adsorption on the surface under neutral conditions. Due to the hydrophilicity of the silica, multiple hydration layers would form on its surface, hindering the further adsorption of SDZ molecules on its surface. The calculated soil-water partition coefficient (Psoil/water) of SDZ+ and SDZ were 9.01 and 7.02, respectively. The adsorption evaluation and mechanisms are useful in controlling the migration and transformation of SAs in the soil environment. These findings provide valuable insights into the interactions between SDZ and soil components, shedding light on its fate and transport in the environment.

The Effect of Dietary Synbiotics in Actively Racing Standardbred Horses Receiving Trimethoprim/Sulfadiazine

Synbiotics are often provided to horses receiving antibiotics to protect against microbiome disturbances, despite a lack of evidence for efficacy. The purpose of this study was to evaluate the effect of a synbiotic product in horses receiving antibiotics. Sixteen actively racing Standardbred horses were randomly allocated (four-way crossover) to one of four groups: antibiotics (10 days; AB), synbiotics (28 days; PROBIOPlus^TM; PBP), PBP + AB, or Control. The fecal microbiome was investigated using 16S rRNA sequencing, and fecal dry matter (DM; %), pH, and scores (FS; 0-9) were measured. Data were analyzed with two-way ANOVA. Results found microbiota differences in community membership between PBP + AB and all other treatments during and after antibiotic treatment. During antibiotic treatment, AB and PBP + AB were significantly different from Control. After antibiotic treatment, PBP + AB was significantly different from all other treatments. The few differences found in relative abundance of phyla or predominant genera were mostly in fiber degrading bacteria. The Fibrobacter population was significantly higher in AB and PBP + AB horses than Control. Unclassified Ruminococcaceae was significantly higher in Control than AB and PBP. After antibiotic treatment, PBP + AB horses were significantly higher than PBP horses. In conclusion, these data provide support for the ability of PROBIOPlus™ to maintain healthy gastrointestinal microbiome during antibiotic treatment.

Cefquinome Sulfate Oily Nanosuspension Designed for Improving its Bioavailability in the Treatment of Veterinary Infections

Introduction

Cefquinome sulfate (CS) is the first fourth-generation antibiotic for animals, which has a wide antibacterial spectrum, strong antibacterial activity and low drug resistance. However, it is accompanied by problems of poor therapeutic efficacy. In this context, the use of nanosuspensions have been found to be an attractive strategy. The main objective of this work is to develop a new oily nanosuspension to improve bioavailability and stability of CS formulations.

Methods

After screening the formulations, cefquinome sulfate oily nanosuspension (CS-NSP) was prepared by mortar grinding, using propylene glycol dicaprolate/dicaprate (Labrafac™ PG) as oil medium and caprylocaproyl polyoxyl-8 glycerides (Labrasol®) as stabilizer. The properties of CS-NSP were investigated by testing its physicochemical characteristics, stability, in vitro release, hemolysis, and muscle irritation. The in vivo pharmacokinetics of CS-NSP was studied using rats.

Results

Results show that CS-NSP presents suitable stability, physicochemical properties and safety. Moreover, a rapid release and high bioavailability of CS-NSP have also been verified in the study. Pharmacokinetic experiments in vivo showed that the bioavailability of CS-NSP was about 1.6 times that of commercial cefquinome sulfate injection (CS-INJ, Chuangdao®) (p<0.01). These advantages of CS-NSP were carried out by small particle size and low viscosity, being associated with the use of Labrafac PG and stabilizer Labrasol.

Conclusion

The results proved that the new preparation is safe and effective and is expected to become a promising veterinary nanodelivery system.

Dietary supplements of vitamins E, C, and β-carotene to reduce oxidative stress in horses: An overview

Oxidative stress is the excess generation of free radicals and/or a decrease in the response of the antioxidant system. It is known to cause damage to the equine health by unbalancing the stable molecules. The supplements of vitamins E, C, and β-carotene in the diet cause beneficial effect on horses' health. These supplements could transform free radicals into the stable radicals, thereby showing importance in the prevention of diseases associated with oxidative stress. Adding vitamins E, C, and β-carotene to the horses' diets in stressful conditions could decrease the production of free radicals that cause inflammation and tissue damage, the typical characteristics that have been associated with oxidative stress. This review spotlights the available evidence of the benefits of dietary supplements of vitamins E, C, and β-carotene towards the reduction of oxidative stress in horses.

Use of Antibiotics in Equines and Their Effect on Metabolic Health and Cecal Microflora Activities

In the race against deadly diseases, multiple drugs have been developed as a treatment strategy in livestock. Each treatment is based on a specific mechanism to find a suitable drug. Antibiotics have become a fundamental part of the equine industry to treat bacterial diseases. These antibiotics have specific doses and side effects, and understanding each parameter allows veterinarians to avoid or limit the adverse effects of such drugs. Use of antibiotics causes microbial imbalance, decreased microbial diversity and richness in both cecal and fecal samples. Antibiotics reduced metabolites production such as amino acids, carbohydrates, lipids, and vitamins, increased multi-resistant microbes, and gives opportunity to pathogenic microbes such as Clostridium perfringens and Salmonella spp., to overgrow. Therefore, appropriate use of these antibiotics in equine therapy will reduce the adverse consequence of antibiotics on cecal microbiota activities.

Probiotic potential of Lactobacillus isolated from horses and its therapeutic effect on DSS-induced colitis in mice

Inflammatory bowel disease (IBD) is a refractory disease that endangers both humans and animals. In recent times, Lactobacillus have been used to treat animal diseases. It may be a good choice to try to isolate Lactobacillus with probiotic potential to treat IBD. Equine, as a kind of hindgut fermentation animal has rich intestinal microflora, but data regarding this is scarce. The isolation of Lactobacillus with probiotic potential from equine may become a new method for the treatment of IBD. Four isolates of Lactobacillus were isolated from fresh feces of healthy male adult horses and analyzed their biological characteristics. According to the phylogenetic analysis, A2.5 and A7.1 were identified as Pediococcus pentosaceus, A3 as Lactobacillus plantarum, and B8.2 as Weissella cibaria. All four isolates showed tolerance to the environment of acid, bile salt concentration and simulated artificial gastrointestinal fluid. The hydrophobic rate and self-aggregation rate of A3 were close to 100%, and the adhesion rate was 28.85 ± 0.74%. Four isolates were negative in hemolysis test and sensitive to common antibiotics and different isolates had different sensitivity to antibiotics. The four isolates had antibacterial and antioxidant activities which can reflect their probiotic potential. Furthermore, they could regulate the LPS (Lipopolysaccharides) stimulated Caco-2 cells. We chose A3 as the treatment strain to intervene Dextran sulfate sodium salt (DSS)-induced mice. The results showed that compared with DSS group, DSS + A3 group exhibited reduced Disease activity index (DAI), increased colon length, reduced pathological score and regulated cytokine secretion at the level of gene expression. In this study, four isolates of Lactobacillus with probiotic potential were isolated, and Lactobacillus plantarum A3 with reduced ulcerative colitis in mice was screened. It might provide a potential treatment for IBD.