Veterinary Research Forum

Abstract Swine colibacillosis, caused by colonization of the piglet small intestine with enterotoxigenic strains of Escherichia coli, imposes a significant economic burden on the swine industry. Due to high mortality rates and the emergence of antimicrobial resistance, it is considered one of the major welfare concerns in the livestock industry. This study elucidated the genetic basis and expression patterns of key antibiotic resistance genes in porcine E. coli isolates with colibacillosis. Intestinal contents from five affected piglets were subjected to high-throughput sequencing, revealing 26 resistance genes across seven antibiotic classes. Four strains (428, 430, 432, 433) were further analyzed for mRNA expression levels of six resistance genes (blaTEM, tetA, tetB, tetM, qnrB, and qnrS) under exposure to ampicillin, tetracycline and ciprofloxacin at three concentrations (0.01, 0.001, 0.0001% w/v). Our findings revealed five distinct expression patterns: (1) dose dependent upregulation/downregulation, (2) inverse response to concentration changes, (3) maximal downregulation at intermediate dose, (4) minimal down-regulation at intermediate dose, and (5) sustained upregulation. Strain 428 uniformly followed pattern one for all resistance genes, in strain 430, tetB followed pattern three while blaTEM matched pattern one, strain 432 exhibited patterns two for all tetracycline- and β-lactam-resistance genes, and pattern four for qnrB; strain 433 showed patterns three for both fluoroquinolone-resistance genes, pattern four for tetB, and pattern five for blaTEM. These findings highlighted strain-specific and dose-dependent gene expression responses in swine colibacillosis. This work underscored the need for tailored antibiotic strategies, targeted interventions and well-validated monitoring frameworks for antibiotic resistance in veterinary.

Abstract This study aimed to report, for the first time, histopathological lesions caused by an outbreak of acute Actinobacillus pleuropneumoniae serotype 8 infections in two farms in Cyprus. Lung tissue samples were collected from two different affected farms (a total of eight samples) for bacterial culture, multiplex polymerase chain reaction (PCR)-based serotyping and histopathological evaluation. Severe respiratory clinical signs, vomiting, anorexia, sudden deaths, a morbidity rate of around 25.00% and a mortality rate of over 60.00% in the fattening stage were reported. Macroscopic lesions included acute to subacute fibrotic, hemorrhagic and necrotizing pneumonia with occasionally encapsulated nodule-like abscesses and fibrous pleuritis. Histopathological evaluation revealed fibrous exudate between alveolar spaces and connective tissue, areas of necrosis mixed with alveolar macrophages, lymphocytes, plasma cells and necrotic leukocytes surrounding colonies of cocci. The bronchial and bronchiolar epithelia were degenerated and replaced by eosinophilic cell debris mixed with inflammatory cells. Several arteries and capillaries were clotted and/or infiltrated by inflammatory cells. In conclusion, these A. pleuropneumoniae serotype 8 cases were accompanied by acute illness, death and more pronounced bronchitis and bronchiolitis.

Abstract Trichinellosis is an important zoonosis and the most common source of human infection is meat from pigs and wild boars. The European Union (EU) supports alternative pig production systems (organic and free-ranging) as sustainable farming systems. However, these systems that allow outdoor access for farm animals, may create new or reintroduce old risks to public health. During the last years, alternative pig production systems (free-ranging or organic pig) are growing in popularity in Greece due to the increasing interest of consumers for organic products. The majority of the trichinellosis outbreaks in the EU were associated with pork and meat products including wild boars. In Greece, from 2009 to 2012, 37 Trichinella spp. positive free-ranging pigs were reported in free-ranging pig farms of Northern-Eastern Greece (31 were identified as T. britovi). The recent re-emerging present of the Trichinella spp < em>. infections in free-ranging pigs and wild boars are a high risk for the consumers and should alarm the Public Health Authorities in Greece and the EU. During the last years, the organic or free-ranging pig production systems are growing in popularity in the EU. However, these systems increase the risk of Trichinella spp. infections, since pigs are possible to be infected by feeding on carcasses or the offal of hunted or dead wild animals. For this reason, it is important for Public Health Authorities to be focused on the training of hunters and farmers in order to avoid the transmission among free-ranging pigs and prevent the cases of human infection.

The recent re-emerging presence of the Trichinella spp. infections in free ranging pigs and wild boars is a high risk for the consumers and should alarm the Public Health Authorities in Greece and EU. During last years, the organic or free-ranging pig production systems are growing in popularity in EU. However, these systems increase the risk for Trichinella spp. infections, since pigs are possible to be infected by feeding on carcasses or the offal of hunted or dead wild animals. For this reason, it is important Public Health Authorities to be focused on the training of hunters and farmers in order to avoid the transmission among free ranging pigs and prevent the cases of human infection.

Abstract Porcine necrotic ear syndrome (PNES) in pigs has been reported as an increasing health problem in many countries with intensive pig farming. The etiology of this disease is complex and the presumed triggering factors can be divided into infectious and non-infectious agents. The present report describes a case of Porcine Circovirus type 2 (PCV2), infection associated with lesions of PNES at the weaning stage of a farrow-to-finish pig farm. Approximately 35% of weaners (1-3 weeks after weaning) presented clinical symptoms similar to Post-weaning Multisystemic Wasting Syndrome (PMWS). About 2-3 weeks after weaning the first lesions of PNES occurred in approximately 20% of pigs, resulting in a significant health problem characterized by poor growth or severe wasting and finally mortality up to 15% in some batches. Moreover, approximately 5% of survived weaners, during growing / finishing stage, presented poor growth and secondary co-infections that lead to death. The present study based on the clinical signs, serological and pathological examinations, indicates that weaners suffered by sub-acute PCV2 infection resulting in PMWS associated with PNES. The lesions of PNES were initially observed at the same period (4-8 weeks of age) with the higher seroprevalence of PCV2 infection. Metaphylaxis of this case included intramuscular injection of florfenicol for the treatment and control of skin lesions and respiratory signs. Moreover, piglets were vaccinated against PCV2. In conclusion, sub-acute PCV2 infection could be included in triggering factors PNES in weaners. The mass vaccination against PCV2 of infected piglets might be effective in reduction of clinical signs and losses of PNES in cases of PCV2 infection associated with PNES.