Salmonella enterica is one of the most dangerous foodborne pathogens listed by the World Health Organization. In this study, whole-duck samples were collected at wet markets in five districts in Hanoi, Vietnam, in October 2019 to assess their Salmonella infection rates and evaluate the susceptibility of the isolated strains to antibiotics currently used in the prophylaxis and treatment of Salmonella infection. Based on the antibiotic resistance profiles, eight multidrug resistance strains were whole-genome-sequenced, and their antibiotic resistance genes, genotypes, multi-locus sequence-based typing (MLST), virulence factors, and plasmids were analyzed. The results of the antibiotic susceptibility test indicate that phenotypic resistance to tetracycline and cefazolin was the most common (82.4%, 28/34 samples). However, all isolates were susceptible to cefoxitin and meropenem. Among the eight sequenced strains, we identified 43 genes associated with resistance to multiple classes of antibiotics such as aminoglycoside, beta-lactam, chloramphenicol, lincosamide, quinolone, and tetracycline. Notably, all strains carried the bla_CTX-M-55 gene, which confers resistance to third-generation antibiotics including cefotaxime, cefoperazone, ceftizoxime, and ceftazidime, as well as resistance genes of other broad-spectrum antibiotics used in clinical treatment such as gentamicin, tetracycline, chloramphenicol, and ampicillin. Forty-three different antibiotic resistance genes were predicted to be present in the isolated Salmonella strains’ genomes. In addition, three plasmids were predicted in two strains, 43_S11 and 60_S17. The sequenced genomes also indicated that all strains carried SPI-1, SPI-2, and SPI-3. These SPIs are composed of antimicrobial resistance gene clusters and thus represent a potential threat to public health management. Taken together, this study highlights the extent of multidrug-resistant Salmonella contamination in duck meat in Vietnam.

A CE-C ⁴ D method was developed as a low-cost alternative to HPLC for screening PDE-5 inhibitor analogs in supplements. Undeclared sildenafil and homosildenafil were found in male sexual-enhancement products at up to 58.4 and 16.1 mg g ⁻¹ , respectively.

The mixing of unpermitted drugs with health supplements to increase effectiveness can cause negative effects to consumers, requiring quality testing of these products. In this study, an analytical method for simultaneously determination of 5 anti-diabetic drugs (ADDs) (i.e., metformin, phenformin, buformin, glibenclamide, and gliclazide) in health supplement samples was developed with a combination of ultrasonic extraction, dispersive solid-phase extraction (d-SPE), and liquid chromatography tandem mass spectrometry (LC-MS/MS). Hard capsule, soft capsule, and liquid samples were extracted with methanol twice, followed by activated carbon addition for extract clean-up and LC-MS/MS quantification. The analytical method was validated through various factors such as: specificity, limit of detection, limit of quantification, linearity, repeatability, and recovery. The method had high precision (mean recovery from 88% to 99%, relative standard deviation lower than 10%) and low detection limit of 0.1 mg/kg, meeting the requirements of detection of these substances at trace to ultra-trace levels in complex sample matrices. The validated method was then applied to analyze concentrations of 5 ADDs in 30 health supplement samples. Metformin was detected at a concentration of 2.20 mg/kg in one hard capsule sample, while the remaining samples did not contain ADDs at detectable levels.