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.

Re-Emergence of Salmonellosis in Hog Farms: Outbreak and Bacteriological Characterization.

Clinical salmonellosis has been increasing significantly in Brazil in recent years. A total of 130 outbreaks distributed among 10 swine-producing states were investigated. One representative Salmonella isolate from each outbreak was characterized through serotyping, antimicrobial resistance profiles, PFGE, and WGS. From 130 outbreaks: 50 were enteric, 48 were septicemic, 17 cases were characterized as hepato-biliary invasive, 13 as nodal and two were not classified. The most prevalent serovars were a monophasic variant of S. typhimurium (55/130), Choleraesuis (46/130), and Typhimurium (14/130). Most of the strains (86.92%) demonstrated a high rate of multi-drug resistance. The identification of a major Choleraesuis clonal group in several Brazilian states sharing the same resistance genes suggested that these strains were closely related. Six strains from this clonal group were sequenced, revealing the same ST-145 and 11 to 47 different SNPs. The detected plasmid type showed multiple marker genes as RepA_1_pKPC-CAV1321, the first to be reported in Salmonella. All AMR genes detected in the genomes were likely present on plasmids, and their phenotype was related to genotypic resistance genes. These findings reveal that salmonellosis is endemic in the most important pig-producing states in Brazil, emphasizing the need to make data available to aid in reducing its occurrence.

Atividade antibacteriana de desinfetantes para uso na produção orgânica de aves / Antibacterial activity of disinfectants for use in organic poultry keeping

A determinação de produtos eficazes para a desinfecção e que não causem danos ao meio ambiente é um grande desafio para a avicultura orgânica. Neste trabalho foram avaliadas as atividades antibacterianas de quatro desinfetantes: ácido peracético, amônia quaternária, hipoclorito de sódio a 1 por cento e a 0,1 por cento de cloro ativo e do composto de ácidos orgânicos (cítrico, lático e ascórbico), frente às amostras padrão de Escherichia coli, Salmonella enteritidis e Staphylococcus aureus, na presença e ausência de matéria orgânica, sob duas diferentes temperaturas e tempo de contato de 20 minutos. Os ácidos orgânicos mostraram-se menos efetivos na presença de matéria orgânica. No entanto, o ácido peracético, na ausência desta, foi o mais eficaz frente à S. Enteritidis e igualmente efetivo, independente da matéria orgânica, frente ao S. aureus e E. coli, revelando-se uma opção válida para desinfecção na avicultura orgânica, desde que precedida de limpeza criteriosa.

Efficient products in the disinfection that do not cause damages to the environment are a challenge for the organic poultry keeping. The antibacterial activity of four disinfectants was evaluated to per acetic acid, quaternary ammonium, sodium hypochlorite at 1 percent and 0,1 percent and the composed of organics acids (citric, lactic and ascorbic) against standard samples of Escherichia coli, Salmonella enteritidis and Staphylococcus aureus in the presence and absence of organic matter, at two different temperatures and with 20 minutes of contact. Organic acids were shown less effective in the presence of organic matter. However, the per acetic acid in the absence of this revealed most efficient against S. Enteritidis and equally effective in the presence of organic matter, against S. aureus and E. coli showing a valid option for disinfection in the organic poultry keeping since preceded of careful cleanness.

Variable number of tandem aminoacid repeats in adhesion-related CDS products in Mycoplasma hyopneumoniae strains.

The Mycoplasma hyopneumoniae genome contains at least 22 regions with a variable number of tandem nucleotide repeats (VNTRs) within coding DNA sequences (CDSs). In this work, the VNTR-containing CDSs were analysed in order to evaluate their degree of variation, possible correlations with antigenic properties, and their potential to be used as a basis for a strain typing PCR assay. We have analysed the VNTRs in five M. hyopneumoniae strains (J, 7448, 7422, PMS, and 232), based on published genomic sequences and on amplified and sequenced DNA segments. These VNTRs are distributed among 12 genes, most of which encode putative surface proteins, including known adhesins. The number of repeat units in any of the VNTRs is highly variable among the analysed strains, but they are, without exception, translationally in frame, and, therefore, code for a variable number of aminoacid repeats (VNTARs). These VNTARs determine putative structural, physicochemical and antigenic variations in the corresponding proteins, with potential implications for aspects associated to M. hyopneumoniae pathogenicity, such as cell adhesion and interactions with the host immune system. Considering that the characterized VNTARs are relatively stable, at least in vitro, and their sizes are strain-specific, we have developed a VNTR-based PCR assay for M. hyopneumoniae strain identification, useful for enzootic pneumonia (EP) diagnosis, strain typing, and distinction of circulating field isolates from vaccine strains in animals vaccinated against EP.