To ensure delivery of safe foods to consumers, withdrawal times for drugs must be respected according to the maximum residual limits established by regulatory agencies. Because of availability and price, feather meal is currently incorporated into animal feed as a protein source for farm species. Few data are available on residual drugs in feathers from treated animals. A depletion study was performed with laying hens treated intramuscularly with 5% enrofloxacin (Enromic) at 10 mg/kg body weight over 3 days. Thirty-three birds were treated and slaughtered at different times between 6 and 216 h after treatment; and samples of muscle plus skin, liver, kidney, and feathers were collected. High-performance liquid chromatography coupled with a tandem mass spectrometry method was validated before sample analysis to determine the decision limit, detection capability, recovery, and precision. Liver was the edible tissue with the slowest drug depletion. A withdrawal time of 6 days was calculated based on European Union maximum residual limits (100 microg/kg). A withdrawal time of 9 days was calculated based on Japan maximum residual limits (10 microg/kg). Enrofloxacin plus ciprofloxacin concentrations in feathers remained high through all sampling periods. Thus, feathers from treated animals should not be fed to food-producing animals.

Salmonella Infantis is a zoonotic pathogen that causes gastroenteritis in humans and animals, with poultry being its main reservoir. In Chile, there are no data to characterize S. Infantis strains in poultry production. In this study, 87 S. Infantis strains were isolated from chicken meat for sale in supermarkets in Santiago, Chile, and characterized according to their virulence genes, biofilm formation abilities, antibiotic susceptibility, and resistance genes. Through polymerase chain reaction or PCR, the strains were analyzed to detect the presence of 11 virulence genes, 12 antibiotic resistance genes, and integrase genes. Moreover, disc diffusion susceptibility to 18 antimicrobials and the ability to form biofilm in vitro were evaluated. Results demonstrated six different virulence gene profiles. Ninety-four percent of the strains were multi-resistant to antibiotics with weak biofilm formation abilities, 63.2% of the strains were broad spectrum β- lactam resistant, and the bla CTX-M-65 gene was amplified in 13 strains. Only 3.4% of the strains were fluoroquinolone resistant, and the qnrB gene was amplified in two strains. Colistin resistance was exhibited in 28.7% of the strains, but mrc genes were not amplified in any strain under study. The isolated S. Infantis strains are pathogenic and antibiotic multi-resistant, and thus, this Salmonella serotype should be under surveillance in the poultry food production chain with the aim of protecting public health.

No abstract

The aim of this research was to identify the presence of integrons among Escherichia coli strains isolated from poultry and swine and to characterize the topological association of these integrons with resistance genes and assess their potential ability to transfer these elements by conjugation. One hundred and seventy-two strains of E. coli were isolated. Their resistance to tetracycline, streptomycin, sulfamethoxazole-trimethoprim, ciprofloxacin, and enrofloxacin was studied by plate dilution. In resistant strains the presence of integrons and resistance genes was assessed by PCR. In the variable region, genes aadA1, dfrA1, and qnr were analyzed. Also, presence of tetA, tetB, and sul1 was assessed. Transference of these genes and integrons in vitro was evaluated by conjugation assays, using E. coli J53 Az(r) as recipient strain. Seventy-eight percent and 83% of the poultry and swine strains, respectively, were resistant to at least one of the studied antimicrobials. Of the isolated strains 91 presented integrons. Resistance genes detected within the integrons were aadA1, dfrA1, and sat1. Gene qnr was not detected. Genes tet and sul1 were identified in 105 and 53 strains, respectively. Seven strains transferred their resistance determinants by conjugation. The results verify the high percentage of antibiotic resistance in the E. coli strains isolated, and these represent a reservoir of resistance genes and integrons.

Cortisol availability is modulated by several enzymes: 11β-HSD2, which transforms cortisol (F) to cortisone (E) and 11β-HSD1 which predominantly converts inactive E to active F. Additionally, the A-ring reductases (5α- and 5β-reductase) inactivate cortisol (together with 3α-HSD) to tetrahydrometabolites: 5αTHF, 5βTHF, and THE. The aim was to assess 11β-HSD2, 11β-HSD1, and 5β-reductase activity in hypertensive patients. Free urinary F, E, THF, and THE were measured by HPLC-MS/MS in 102 essential hypertensive patients and 18 normotensive controls. 11β-HSD2 enzyme activity was estimated by the F/E ratio, the activity of 11β-HSD1 in compare to 11β-HSD2 was inferred by the (5αTHF + 5βTHF)/THE ratio and 5β-reductase activity assessed using the E/THE ratio. Activity was considered altered when respective ratios exceeded the maximum value observed in the normotensive controls. A 15.7% of patients presented high F/E ratio suggesting a deficit of 11β-HSD2 activity. Of the remaining 86 hypertensive patients, two possessed high (5αTHF + 5βTHF)/THE ratios and 12.8% had high E/THE ratios. We observed a high percentage of alterations in cortisol metabolism at pre-receptor level in hypertensive patients, previously misclassified as essential. 11β-HSD2 and 5β-reductase decreased activity and imbalance of 11β-HSDs should be considered in the future management of hypertensive patients.