The phenotypic and genotypic antimicrobial resistance patterns of Salmonella isolated from chickens and meat at poultry slaughterhouses in Japan and Thailand.

Background and Aim: Poultry meat is a popular food consumed globally. However, poultry farming is a source of Salmonella contamination which causes human salmonellosis. This study aimed to estimate the prevalence and antimicrobial resistance (AMR) of Salmonella among chickens and meat at poultry slaughterhouses in province study areas in Thailand and Japan. Materials and Methods: Chicken meat and feces samples were collected in Thailand and Japan. In Nakhon Ratchasima Province, Thailand, 558 samples were obtained from slaughterhouses from January 2021 to March 2022. In Gifu Prefecture, Japan, 140 samples (70 each of intestinal contents and meat) were purchased from slaughterhouses from June to October 2022. For Salmonella detection, the samples were cultivated according to the International Organization for Standardization 6579:2002/AMD 1:2007 method and confirmed using polymerase chain reaction (PCR) and agglutination tests for serotyping. Isolated Salmonella were tested for AMR to nine antibiotics using the disk diffusion method. Selected phenotypic multidrug-resistant (MDR) isolates were evaluated for AMR genes (AMRGs) using PCR. Results: Salmonella prevalence from chickens and meat at slaughterhouses in Thailand and Japan was 41.2% and 40.7%, respectively. All the Salmonella isolates in Japan were serotyped as Schwarzengrund, and no Salmonella isolates were resistant to the nine antibiotics tested. In contrast, most of the Thai Salmonella isolates from chicken cloacal swabs and meat were resistant to doxycycline (78.3%) and colistin (63.5%). The prevalence of MDR Salmonella (MDRS) in chickens and meat from Thailand and Japan was 29.1% (67/230) and 0% (0/57), respectively. However, the most frequent AMRGs found in MDRS in Thailand were extended-spectrum beta-lactamase-Temoneira (ESBL-TEM) (45.1%). All isolated Salmonella from Japan revealed a class 1 integron gene (Int-1). Conclusion: Phenotypic MDRS isolates from Thailand showed the greatest correlation to AMRG and ESBL-TEM. Although there were no phenotypic AMR Salmonella isolates found in Japan, they can be found associated with Int-1, which may carry other AMRGs within the gene cassettes.

Experimental in utero inoculation of late-term swine fetuses with porcine circovirus type 2.

All 37 fetuses of 3 laparotomized pregnant sows at 86, 92, and 93 days of gestation were inoculated intramuscularly through the uterine wall with porcine circovirus type 2 (PCV-2). The sows were allowed to farrow, and blood and tissue samples were collected from their piglets before and after suckling colostrum. Thirteen fetuses from 2 sows at 90 and 103 days of gestation were used as controls. Of the 37 PCV-2 inoculated fetuses, 24 were grossly normal and 13 were mummified, stillborn, or weak-born at farrowing. Infection with PCV-2 was demonstrated in various tissues of grossly normal and abnormal fetuses by virus isolation, polymerase chain reaction, and immunohistochemical methods. Antibodies specific to PCV-2 were also detected from the sera or thoracic fluids of abnormal fetuses and unsuckled normal pigs. No evidence of PCV-2 infection was found in any control fetuses. The present results confirm previous findings that PCV-2 can infect late-term swine fetuses and may cause reproductive abnormalities.

An immunoperoxidase monolayer assay for the detection of antibodies against swine influenza virus.

An immunoperoxidase monolayer assay (IPMA) has been developed to detect antibodies against swine influenza A virus (SIV) in pig sera. The test was evaluated by using sequential sera from pigs experimentally infected with H1N1 subtype of SIV. Two hundred field serum samples that had been examined by the hemagglutination inhibition (HI) test were also tested. Antibodies specific to SIV were detected as early as 3 days postinoculation (dpi) in the IPMA test as compared with 7 dpi by the HI test. Unlike HI, no serum treatment was required in the IPMA test. Regardless of the virus used in the test, IPMA detected antibodies to both H1N1 and H3N2 subtypes of SIV whereas HI detects antibodies against either H1N1 or H3N2, depending upon the virus used in the test. Results of this study indicate that IPMA is a useful test for screening of pig sera for SIV antibodies.