No abstract

Clostridium perfringens infection causes subclinical and clinical necrotic enteritis in poultry flocks, and it is estimated to result in US$2 billion of losses worldwide every year. The aims of this study were to determine the incidence, toxin types, and antimicrobial resistance levels to C. perfringens isolated from premarket, 5-wk-old, clinically healthy broiler chickens in Taiwan, and to examine the relationships between intestinal lesions and the numbers of C. perfringens in intestinal contents. In total, 435 samples of chicken ileum contents were collected from 98 broiler farms during June 2012 to February 2013. The C. perfringens isolation rate was 9.9% (43/435). The positive rate of tested farms was 29.6% (29/98). All the isolates were C. perfringens type A, only possessing the cpa gene encoding for toxin α. No netB gene encoding NetB toxin associated with necrotic enteritis, and no cpe gene encoding for the C. perfringens enterotoxin causing human intestinal disorder were detected. A quantitative PCR analysis revealed that the mean C. perfringens number in the intestinal contents was 3.9 × 10(6) colony-forming units (CFU)/g, ranging from 6.85 × 10(2) to 1.61 × 10(7) CFU/g. The gross and histopathologic lesions revealed a positive correlation (p < 0.05) between lesion score and C. perfringens number in the ilea of C. perfringens -positive chickens. Antimicrobial susceptibility tests of all C. perfringens isolates indicated that the minimum inhibitory concentration inhibiting 50% of isolates (MIC50) for amoxicillin, bacitracin, chlortetracycline, enrofloxacin, erythromycin, florfenicol, and lincomycin was ≤0.125, 0.5, 128, 0.25, ≥256, 2, and ≥256 μg/ml, respectively. Most of the C. perfringens isolates were susceptible to amoxicillin, bacitracin, and enrofloxacin but resistant to chlortetracycline, erythromycin, and lincomycin. Interestingly, C. perfringens isolated from chickens with severe lesions had higher MIC50 for erythromycin and lincomycin than those isolates from chickens with mild lesions. Conclusively, reductions in both the incidence of C. perfringens infection on farms and the concentrations of C. perfringens in intestines to improve broiler health are still needed in Taiwan.

Infection by Salmonella Enteritidis (SE) causes decreased egg production in laying hens. Immunoresponse, steroidogenesis, and cell proliferation by chicken granulosa cells (cGCs) are of particular interest because these changes are involved in follicular growth, atresia, and ovulation. To elucidate the possible mechanisms underlying these changes, transcriptional alterations in cGCs at distinct stages of follicular maturity were studied. Luteinizing hormone (LH)-and follicle-stimulating hormone (FSH) were applied to the cGCs isolated from hierarchical and prehierarchical follicles, respectively, to imitate the effects of gonadotropin during in vitro SE infection. Results showed that the expression of Toll-like receptor 15 was dependent on the follicular maturity, with mature cells having a more significant and progressively stronger immunoresponse. Attenuated responses to LH and FSH as well as retardant steroidogenesis due to down-regulated LH receptor, FSH receptor, and the P450 side-chain cleavage system were observed and may have led to delayed hierarchical follicular growth. Deteriorated cell viability of prehierarchical follicles may occur, as the proliferation of stimulator heparin-binding epidermal growth factor was reduced significantly. Furthermore, the infection led to a higher probability of cGCs from the smaller follicles undergoing apoptosis than those from F1 follicles. Collectively, the data provide evidence of a tendency toward pathogen elimination in F1 follicles by induction of a strong immune response and cell apoptosis in smaller follicles to avoid bacterial transovarian infection. It is our speculation that slowed steroidogenesis and impeded follicular growth may play essential roles in decreased ovulation rate as well as further decreased egg production during SE infection.

A 2-year study was performed at two ready-to-eat tilapia sashimi processing plants (A and B) to identify possible routes of contamination with Listeria monocytogenes during processing. Samples were collected from the aquaculture environments, transportation tanks, processing plants, and final products. Seventy-nine L. monocytogenes isolates were found in the processing environments and final products; 3.96% (50 of 1,264 samples) and 3.86% (29 of 752 samples) of the samples from plants A and B, respectively, were positive for L. monocytogenes . No L. monocytogenes was detected in the aquaculture environments or transportation tanks. The predominant L. monocytogenes serotypes were 1/2b (55.70%) and 4b (37.97%); serotypes 3b and 4e were detected at much lower percentages. At both plants, most processing sections were contaminated with L. monocytogenes before the start of processing, which indicated that the cleaning and sanitizing methods did not achieve adequate pathogen removal. Eleven seropulsotypes were revealed by pulsed-field gel electrophoresis and serotyping. Analysis of seropulsotype distribution revealed that the contamination was disseminated by the processing work; the same seropulsotypes were repeatedly found along the work flow line and in the final products. Specific seropulsotypes were persistently found during different sampling periods, which suggests that the sanitation procedures or equipment used at these plants were inadequate. Plant staff should improve the sanitation procedures and equipment to reduce the risk of L. monocytogenes cross-contamination and ensure the safety of ready-to-eat tilapia products.

No abstract

Salmonella enterica serovar Enteritidis (SE) is a public health concern and infected chickens serve as a reservoir that potentially transmits to humans through food. Although SE seldom causes systemic disease in chickens, virulent SE strains can colonize in intestines and lead a persistent infection of the liver. The liver is the primary organ for lipid metabolism in chickens and the site for production and assembly of main components in yolk. We performed a time-course experiment using LMH-2A cells that were infected with SE and co-incubated with β-oestradiol to evaluate if SE infection affected lipid metabolism and subsequently changed lipoprotein formation for egg yolk. The results indicated that lipid accumulation significantly increased in infected LMH-2A cells while the viability of these cells was only slightly decreased. The mRNA expressions of lipid transportation and most lipogenetic genes including sterol regulatory element binding protein 1, acetyl-CoA carboxylase, fatty-acid synthase, long-chain-fatty-acid-CoA ligase 1, peroxisome proliferator-activated receptor-γ, and very-low-density lipoproteins (VLDLs) II were significantly up-regulated while the expression of lipogenetic-related stearoyl-CoA denaturase 1 was down-regulated. Moreover, decline in lipid transportation of hepatocytes was evidenced by the down-regulation of oestrogen receptor α which promotes VLDLy formation, an increase of intra-cellular accumulation of Apoprotein B (ApoB) protein, and a decrease of cellular excretion of VLDL protein. Conclusively, SE infection could elevate lipid synthesis and reduce lipid transportation in the chicken hepatocytes. These changes may lead excessive lipid accumulation in liver and slower lipoprotein deposition in yolk.

No abstract

We tested 137 samples of domestic shucked oysters and 114 samples of imported oysters collected from traditional retail markets and supermarkets during 2010 and 2011 in Taiwan for the presence of Salmonella . We obtained a total of 91 Salmonella isolates, representing nine serotypes, from 80 of the domestic samples. We did not find any Salmonella in the imported oysters. The presence of Salmonella contamination tended to be specific to the area from which the oysters were harvested: the Dongshih area had a significantly higher contamination rate (68.8%) than the Budai (20.0%) and Wanggong (9.1%) areas. In addition, the rate of Salmonella contamination was higher in oysters that were packed or sold with water (P < 0.05). The most commonly identified Salmonella serotypes were Saintpaul (26.4%), Newport (22.0%), and Infantis (13.2%). We screened the isolates for susceptibility to nine antimicrobials and compared them genetically by using PCR for the class 1 integron (int1), tetA, tetB, and bla genes. Eighteen isolates (19.8%) were resistant to at least one antimicrobial agent, and the most frequent resistances were those to tetracycline and oxytetracycline (n = 12, 14.3%).We detected the antimicrobial resistance genes int1, tetA, tetB, and bla in 16.5, 26.4, 6.6, and 22.0% of the isolates, respectively. Eleven of the 18 antimicrobial-resistant isolates contained one or two int1 cassettes, suggesting that the presence of int1 is highly correlated with antimicrobial resistance in Salmonella isolates from oysters. The consumption of oysters is increasing in Taiwan, and information related to Salmonella contamination in oysters is rather limited. Our results indicate that raw oyster consumption from retail markets in Taiwan is associated with a human health hazard owing to Salmonella , including multidrug-resistant Salmonella strains.