Tildipirosin: An effective antibiotic against Glaesserella parasuis from an in vitro analysis

Preparation and characterization of tildipirosin-loaded solid lipid nanoparticles for the treatment of intracellular Staphylococcus aureus infections

To enhance the antibacterial efficacy of tildipirosin against Staphylococcus aureus (S.A.) infections, optimized solid lipid nanoparticles loaded with tildipirosin (SLN-TD) were developed, using docosanoic acid (DA), octadecanoic acid (OA), hexadecanoic acid (HA), and tetradecanoic acid (TA) as lipid components. The efficacy of these nanoparticles against S.A. was evaluated using orthogonal design analysis. FTIR, DLS, HPLC, and TEM analyses confirmed that tildipirosin was successfully incorporated into the solid lipid nanoparticles, resulting in an optimal nanoparticle drug delivery system with a particle size of 322.63 ± 1.51 nm, a zeta potential of 37.83 ± 0.95 mV, an encapsulation efficiency of 82.23 ± 0.45%, and a drug loading capacity of 7.36 ± 0.18%. The SLN-TD system exhibited high stability, effective sustained release in vitro, and enhanced intracellular activity against S.A. Pharmacokinetic studies in rats administered 4 mg kg-1via intramuscular and oral routes showed that, compared to unencapsulated tildipirosin (TD), SLN-TD provided sustained release in vivo and improved gastrointestinal absorption with higher bioavailability. Additionally, in a mouse model of S.A. infection, SLN-TD demonstrated superior antibacterial activity and sustained drug delivery for effective treatment. This study offers a promising multifunctional nanoparticle drug delivery system for the effective treatment of S.A. infections and enhances the oral bioavailability of tildipirosin, with potential applications in veterinary medicine.

Concerns about the use of antimicrobials in swine herds and alternative trends

Pig productivity in Brazil has advanced a lot in recent decades. Specialized breeds are more vulnerable to pathogens, which has boosted the use of antimicrobials by farmers. The selective pressure generated favors the emergence of resistant bacteria, which compromises the effectiveness of this treatment and limits therapeutic options. In addition to increasing costs and mortality rates in the production system, public awareness of this issue has increased. The authorities have imposed restrictive measures to control the use of antimicrobials and have banned their use as growth promoters. This literature review highlights biosecurity and animal welfare to prevent pig diseases. Hence, we describe alternatives to the use of antimicrobials in pig production for the selection of effective non-antibiotic feed additives that help maintain good health and help the pig resist disease when infection occurs.

Brazilian Clinical Strains of Actinobacillus pleuropneumoniae and Pasteurella multocida: Capsular Diversity, Antimicrobial Susceptibility (In Vitro) and Proof of Concept for Prevention of Natural Colonization by Multi-Doses Protocol of Tildipirosin

One hundred Actinobacillus pleuropneumoniae (App) and sixty Pasteurella multocida subsp. multocida serogroup A (PmA) isolates were recovered from porcine pneumonic lungs collected from eight central or southern states of Brazil between 2014 and 2018 (App) or between 2017 and 2021 (PmA). A. pleuropneumoniae clinical isolates were typed by multiplex PCR and the most prevalent serovars were 8, 7 and 5 (43, 25% and 18%, respectively). In addition, three virulence genes were assessed in P. multocida isolates, all being positive to capA (PmA) and kmt1 genes, all negative to capD and toxA, and most of them (85%) negative to pfhA gene. The susceptibility of both pathogens to tildipirosin was investigated using a broth microdilution assay. The percentage of isolates susceptible to tildipirosin was 95% for App and 73.3% for PmA. The MIC50 values were 0.25 and 1 μg/mL and the MIC90 values were 4 and >64 μg/mL for App and PmA, respectively. Finally, a multiple-dose protocol of tildipirosin was tested in suckling piglets on a farm endemic for both pathogens. Tildipirosin was able to prevent the natural colonization of the tonsils by App and PmA and significantly (p < 0.0001) reduced the burden of Glaesserella parasuis in this tissue. In summary, our results demonstrate that: (i) tildipirosin can be included in the list of antibiotics to control outbreaks of lung disease caused by App regardless of the capsular type, and (ii) in the case of clinical strains of App and PmA that are sensitive to tildipirosin based on susceptibility testing, the use of this antibiotic in eradication programs for A. pleuropneumoniae and P. multocida can be strongly recommended.