[Drug resistance and related genes of chickenborne Salmonella to quinolone and fluoroquinolones].

OBJECTIVE: Antimicrobial susceptibility to quinolone and fluoroquinolones and the related genes of chickenborne Salmonella in Shaanxi, Henan, Sichuan and Beijing provinces were studied to better understand the development of antimicrobial resistance and routes of transmission to ensure food safety. METHODS: Antimicrobial susceptibility was tested according to agar dilution method. GyrA and parC gene mutations of quinolone resistance determination region (QRDR) of fluoroquinolone resistant Salmonella and the resistant genes of qnrA, qnrB, qnrS and aac (6')-Ib-cr were determined using PCR and DNA sequencing analysis. RESULT: Among the 390 Salmonellae isolates, 63.59% were resistant to nalidixic acid, followed by ciprofloxacin (21.28%), levofloxacin (16.67%), and gatifloxacin (14.62%). Among 248 nalidixic acid resistant Salmonella, antimicrobial resistant genes carried by plasmid were detected as aac(6')-Ib-cr (20.16%), qnrA (10.89%), qnrB (10.08%) and qnrS (1.61%), respectively. In total 199 point mutations were detected in gyrA and parC of 83 fluoroquinolone-resistant Salmonella isolates. The most common mutations in gyrA gene was Ser83Phe and Asp87Gly double mutation, followed by Ser83Phe and Asp87Asn double mutation, Ser83Tyr, Ser83Phe, Asp87Gly. Sixty-five point mutations detected in parC was Ser80Arg. CONCLUSION: Antimicrobial resistance of Salmonella recovered from chicken in the four provinces was common. Genetic elements including mutations of unwindase, topoisomerase, and plasmid with antimicrobial, played important roles in the antimicrobial resistance of Salmonella.

Pharmaceuticals and personal care products in water, sediments, aquatic organisms, and fish feeds in the Pearl River Delta: Occurrence, distribution, potential sources, and health risk assessment.

This study investigated the occurrence, distribution, and potential sources of 34 pharmaceuticals and personal care products (PPCPs) in water, sediments, aquatic organisms (fish and shellfish), and fish feeds from the mariculture areas of the Pearl River Delta (PRD). The health risk presented by this class of compounds was also assessed in relation to their intake via seafood consumption. Of the 34 PPCPs, a total of 9, 21, 14, and 28 PPCPs were detected in water, sediments, fish feeds, and aquatic organisms, respectively. Trimethoprim, norfloxacin, ofloxacin, and spectinomycin were detected in all matrices. The levels of PPCPs in water and sediment samples were relatively low. Spectinomycin, paracetamol, ciprofloxacin, norfloxacin, and ibuprofen were the most frequently detected PPCPs in feeds. Ibuprofen and ketoprofen were widely detected in aquatic organisms, with average concentrations of 562 and 267 ng/g wet weight, respectively. The residual levels of PPCPs in shellfish such as ME (mussel, Mytilus edulis) and OS (oyster, Ostrea gigas) were significantly higher (p < 0.05) than those in other species including CA (topmouth culter, Culter alburnus) and EO (orbfish, Ephippus orbis). Correlation analysis indicated that the medicated feeds were a potential source of PPCPs in the mariculture areas of the PRD, but other anthropogenic sources should not be ignored. Based on maximum residue limits and acceptable daily intake, the health risks presented to humans via seafood consumption are negligible. However, as multiple antibiotics were frequently detected in the mariculture environment, aquatic organisms, and feeds, the induction and dissemination of antimicrobial resistance associated with antibiotic usage in aquaculture would be of great concern. It is necessary to establish a centralized management system and control the use of veterinary drugs in mariculture to protect the aquaculture environment and ensure the safety of seafood.

Effects of lead concentration and accumulation on the performance and microbial community of aerobic granular sludge in sequencing batch reactors.

The present study investigated the effects of lead on the morphological structure, physical and chemical properties, wastewater treatment performance and microbial community structure of aerobic granular sludge (AGS) in sequencing batch reactors (SBRs). The results showed that at Pb(2+) concentration of 1 mg/L, the mixed liquid suspended solids decreased, the settling velocity increased and the sludge volume index increased sharply. Meanwhile, AGS began to disintegrate and show an irregular shape. In terms of wastewater treatment in an SBR, the phosphorus removal rate was affected only until the Pb(2+) concentration was up to 1 mg/L. The [Formula: see text] removal efficiency began to decline when the Pb(2+) concentration increased to 6 mg/L, while the removal of chemical oxygen demand increased slightly within the Pb(2+) concentration range of 1-6 mg/L. Significant changes were observed in the microbial community structure, especially the dominant bacteria. Compared to the Pb(2+) accumulation on the sludge, the Pb(2+) concentration in the aqueous phase played a more important role in the performance and microbial community of AGS in SBRs.

Prevalence of Salmonella on raw poultry at retail markets in China.

Data regarding Salmonella on raw poultry are very limited in China. The objective of this study was to determine the prevalence of Salmonella on raw poultry at the retail level in six provinces and two national cities in China. Whole chicken carcasses (n = 1,152) were collected from three types of retail markets (large, small, and wet). All samples were analyzed for the presence of Salmonella by using the U.S. Department of Agriculture, Food Safety Inspection Service method. Of 1,152 chicken samples, overall Salmonella prevalence was 52.2%. The highest prevalence was observed in Guangxi Province (65.3%), next in Guangdong Province (64.6%), and then in Beijing (63.9%), Shaanxi Province (50.7%), Henan Province (47.9%), Shanghai (44.4%), and Fujian Province (42.4%), and lowest prevalence was observed in Sichuan Province (38.9%). Salmonella prevalence was significantly different among the six provinces and two national cities. Salmonella prevalence was highest in the wet markets (54.4%) compared with the large markets (50.3%) and the small markets (52.1%), but differences were not significant (P > 0.05). Good manufacturing practices, good agricultural practices, and hazard analysis critical control point systems for Salmonella control in poultry production at the farm, processing, and retail level should be implemented.