Distribution of Gastrointestinal Parasitic Infection in Domestic Pigs in the Republic of Korea: Nationwide Survey from 2020-2021

This study aimed to examine the distribution of gastrointestinal parasitic infections in domestic pigs in the Republic of Korea. From May 2020 to October 2021, 364 pig fecal samples were collected from 75 farms in 7 Provinces and microscopically examined. A total of 170 (46.7%) pigs were infected with at least one of the following parasites: Balantioides coli, strongyles, Ascaris suum, Trichuris suis, and coccidia. By parasite species, B. coli, strongyles, A. suum, T. suis, and coccidia oocysts or eggs were detected in 144 (39.6%), 24 (6.6%), 14 (3.8%), 4 (1.1%), and 1 (0.3%) samples, respectively. One hundred fifty-four, 15, and 1 cases showed single, double, and triple infections, respectively. Of the swine fecal samples from 75 farms, 69 specimens (92.0%) were infected with 1 or more parasites. All surveyed farms across the country exhibited a positive rate of over 30%, among which the highest positive rate was 65.0% in Chungcheongnam-do, and Jeollabuk-do was followed by 61.9%. Winter showed a statistically lower prevalence than other seasons. This study showed that gastrointestinal parasites are prevalent in pigs in Korea, although the diversity of parasites is low.

Salmonella enterica serotype Choleraesuis infection in weaned pigs: a first clinicopathological case report from Korea

Salmonella enterica serotype Choleraesuis causes swine paratyphoid, with clinical findings of enterocolitis and septicemia. However, the clinicopathological features of S. Choleraesuis infections in pigs have not been reported in Korea. We describe the pathological findings of two weaned pigs with S. Choleraesuis infections, presenting with diarrhea, cough, and sudden death. Pathological examination indicated severe necrotic colitis in pig 1 and septicemic lesions in pig 2. Multidrug-resistant S. Choleraesuis was isolated from the pigs’ lungs and intestinal contents. Further research is required for the surveillance of S. Choleraesuis infections in pigs and the virulence estimation in the S. Choleraesuis isolates.

Virulence and antimicrobial resistance genes of pathogenic Escherichia coli from piglets showing diarrhea before and after ban on antibiotic growth promoters in feed

Abstract: This study examined the prevalence of adherence factors, toxin genes, antimicrobial resistance phenotypes, and resistance genes in Escherichia coli (E. coli) isolated from piglets with diarrhea before and after the ban on antibiotic growth promoters (AGPs) in Korea from 2007 to 2018. In this period, pathogenic 474 E. coli isolates were obtained from diarrheic piglets. The virulence factors and antimicrobial resistance genes were assayed using a polymerase chain reaction, and the susceptibility to antibiotics was tested according to the Clinical and Laboratory Standards Institute guidelines. After the ban on AGPs, the frequency of F4 (12.5% to 32.7%) increased significantly, and LT (31.9% to 20.3%) and EAST-I (46.5% to 35.2%) decreased significantly. In addition, the resistance to streptomycin (45.8% to 67.9%), cephalothin (34.0% to 59.4%), and cefazlin (10.4% to 28.8%) increased significantly. Colistin resistance plasmid-mediated genes, mcr-1 and mcr-3, were detected after the ban on AGPs. The results of this study can provide useful data for analyzing the impact of the ban on AGPs on the virulence profiles and antimicrobial resistance of E. coli isolated from piglets with diarrhea in Korea.

Prevalence of O-serogroups, virulence genes, and F18 antigenic variants in Escherichia coli isolated from weaned piglets with diarrhea in Korea during 2008–2016

To diagnose colibacillosis, detection of O-serogroups and virulence genes has been recommended worldwide. The prevalence of virulence factors can fluctuate over time. The objectives of this study were to determine the prevalence of O-serogroups, virulence genes, and F18 subtypes among pathogenic Escherichia coli isolated from weaned piglets with diarrhea in Korea. Between 2008 and 2016, 362 E. coli were isolated from weaned piglets with diarrhea. Hemolysis was determined in blood agar, and O-serogroups were identified using the slide agglutination technique. The genes for the toxins and fimbriae were amplified by polymerase chain reaction (PCR). Real-time PCR was conducted to discriminate between F18 subtypes. Although the most prevalent serogroup was O149 (11.3%) in the last 9 years, O139 (19.1%) became the most prevalent in recent years (2015–2016). The most predominant pathotype was enterotoxigenic E. coli (61.3%). The frequencies of Shiga-like toxin-producing E. coli (STEC) (23.4%), O139 (19.1%), Stx2e (35.1%), and F18ab (48.7%) increased over the most recent years. Although enterotoxigenic E. coli was the most predominant pathotype, the frequencies of O139, Stx2e, STEC, and F18ab have increased in recent years. These results demonstrate that there have been temporal changes in the predominant O-serogroups and virulence genes over the last decade in Korea. These findings can be practicable for use in epidemiology and control measures for enteric colibacillosis in Korean piggeries.

Comparison of transport media for the isolation and detection of Brachyspira hyodysenteriae / 대한수의학회지

Brachyspira (B.) hyodysenteriae is a causative agent of swine dysentery that is responsible for death and economic losses in the pig industry. It is imperative that clinical samples be delivered fresh for accurate diagnosis. The viability and DNA detection of B. hyodysenteriae using lab-made (phosphate buffered saline and modified tryptic soy broth) or commercial transport media (C, D, and E) were compared by culturing and real-time PCR at 4degrees C or room temperature (RT), respectively. B. hyodysenteriae grown in D (Anaerobe Systems, USA) and E (Starplex Scientific, Canada) media was viable for 4 days at 4degrees C and RT. However, B. hyodysenteriae in A, B, and C (culture swab; BD Biosciences, USA) media were not recovered after 2 days at RT. Ct values for real-time PCR at 4degrees C and RT ranged from 27.2 +/- 2.1 (C) to 29.6 +/- 0.5 (B), and 28.0 +/- 0.9 (E) to 30.2 +/- 1.5 (B), respectively. Considering the field conditions, it is important that transport media is used for specimen isolation and PCR to obtain an accurate diagnosis of swine dysentery.

Loop-mediated isothermal amplification assay for the detection of Salmonella spp. in pig feces / 대한수의학회지

Salmonella are causative agents of gastroenteritis and systemic disease in animals. The invA gene was selected as a target sequence of loop-mediated isothermal amplification (LAMP) assay for diagnosis of Salmonella infection. The detection limits for broth dilution, spiked feces and enrichment were 10(4), 10(5) and 10(2) CFUs/mL, respectively. The LAMP assay developed in the present study may be a reliable method for detection of Salmonella spp. in pig feces.

Antimicrobial resistance and frequency of BlaTEM in Escherichia coli isolated from non-diarrheic and diarrheic piglets / 대한수의학회지

Antimicrobial resistance is one of the most concerns in pig industry. Escherichia (E.) coli have been used for the indicator to monitor the antimicrobial resistance. In this study, 321 E. coli from diarrheic and non-diarrheic piglets were tested for antimicrobial resistance and frequency of Bla TEM. In non-diarrheic piglets, they were resistant to oxytetracycline (93%), streptomycin (92%) and sulfadiazine (90%) but susceptible to ceftiofur (99%), colistin (97%), and enrofloxacin (82%). The isolates from diarrheic piglets were resistant to enrofloxacin (72.9%), ceftiofur (17.6%), and colistin (11.3%), whereas the resistance was 1%, 18% and 3% in case of non-diarrheic piglets, respectively. The resistance for amoxicillin/clavulanic acid (54.1%) and ceftiofur (22%) was high in isolates from post-weaning piglets. The resistance for colistin was 15.2% in nursery piglets. Seventy-three percent of isolates from diarrheic piglets showed high multidrug resistance profile (more than 13 antimicrobials) compared to those from non-diarrheic pigs in which 71% of isolates showed moderate multidrug resistance profile (7 to 12 antimicrobials). The frequency of BlaTEM in E. coli from non-diarrheic and diarrheic piglets was 57% and 69%, respectively. The results might provide the basic knowledge to establish the strategies for treatment and reduce antibiotic resistance of E. coli in piglets.

Serological Survey for Canine Parvovirus Type 2a (CPV-2a) in the Stray Dogs in South Korea

Canine parvovirus type-2 (CPV-2) is one of the major diarrhea-causing agents, inducing acute hemorrhagic gastroenteritis in puppies. In this study, we conducted a seroepidemiological survey of CPV-2a in stray dogs in South Korea. In total, 405 canine sera, collected between 2006 and 2007, were screened for the presence of antibodies against CPV-2a using a hemagglutination inhibition (HI) assay. The positive rate in stray dogs tested for CPV-2a was 93.8%. The regional CPV-2a prevalence was 100% (8/8) in Jeju, 95.1% (232/244) in Gyeonggi, 94.7% (36/38) in Jeonra, 92.9% (13/14) in Gangwon, 92.7% (38/41) in Chungcheong, and 88.3% (53/60) in Gyeungsang province. No significant difference in the seropositive rate was found between male (93.6%) and female (94.0%) dogs. Analysis of the distribution of HI titer against CPV-2a according to the age of the stray dogs showed a linear increase in seroprevalence with age, although the association with age was not statistically significant. The incidence of stray dogs showing an HI antibody titer above 1:5120 was estimated to be 26.2%. Thus, the presence of high HI antibody against CPV-2a may indicate circulation of CPV-2a in stray dogs.

An outbreak of fatal hemorrhagic pneumonia caused by Streptococcus equi subsp. zooepidemicus in shelter dogs

An outbreak of fatal hemorrhagic pneumonia with 70~90% morbidity and 50% mortality occurred in an animal shelter in Yangju, Gyeonggi Province, Korea. Clinically, the affected dogs showed severe respiratory distress within 48 h after arriving in the shelter. The dead were found mainly with nasal bleeding and hematemesis. At necropsy, hemothorax and hemorrhagic pneumonia along with severe pulmonary consolidation was observed, though histopathological analysis showed mainly hemorrhagic bronchopneumonia. Lymphoid depletion was inconsistently seen in the spleen, tonsil and bronchial lymph node. Gram-positive colonies were shown in blood vessels or parenchyma of cerebrum, lung, liver, spleen, and kidney. Also, Streptococcus (S.) equi subsp. zooepidemicus was isolated from the various organs in which the bacterium was microscopically and histologically detected. In addition, approximately 0.9 Kb specific amplicon, antiphagocytic factor H binding protein, was amplified in the bacterial isolates. In this study, we reported an outbreak of canine hemorrhagic bronchopneumonia caused by S. equi subsp. zooepidemicus in an animal shelter in Yangju, Korea.