Antimicrobial resistance of three common molecularly identified pathogenic bacteria to Allium aqueous extracts.

The aim of this work was to evaluate the in vitro bacterial inhibition of different types of garlic on Escherichia coli ATCC 25922, Listeria monocytogenes and Staphylococcus aureus. The bacterial strains were molecularly identified using gen 16S rDNA molecular identification. Four different types of garlics were used: 1) white, 2) Japanese, 3) elephant and 3) black, and these were evaluated at two different concentrations (0.25 and 0.125 g/mL) per garlic type. Bioactive compounds present in the garlics were identified using high-performance liquid chromatography coupled to ultraviolet detector (HPLC-UV), and total polyphenols were quantified by the Folin-Ciocalteu technique. The Kirby-Bauber method was used for the bacterial evaluation. Aqueous extract of black garlic had the highest amount of polyphenols 6.26 ± 0.21 mg GAE/mL. The area of inhibition was measured and classified as sensitive, intermediate or resistant. Using the disc diffusion assay, higher concentration (0.25 g/mL) of aqueous extract of white garlic had the highest antibacterial activity area, with 21.46 ± 3.94 mm for L. monocytogenes, 20.61 ± 2.47 mm for S. aureus and 17.83 ± 2.21 mm for E. coli. White garlic had comparable antimicrobial activity as the control (tetracycline at 30 µg) as indicated by the size of the inhibition halos. Based on your results, white garlic can be used as an alternative to synthetic antimicrobials.

Detection of Quinolone Resistance in Salmonella typhimurium Pig Isolates Determined by gyrA Gene Mutation Using PCR- and Sequence-Based Techniques within the gyrA Gene.

BACKGROUND: The emergence of reduced susceptibility to fluoroquinolones among Salmonella enterica serotype Typhimurium isolates leading to clinical failure of treatment poses a great therapeutic challenge. METHODS: The current study is focused on the evaluation of the minimum inhibitory concentration (MIC) of quinolones in 29 Salmonella typhimurium of 86 Salmonella spp. strains, obtained from pigs from the State of Mexico. The MIC was performed with the Kirby-Bauer method. On the other hand, the GyrA gene was sequenced. The present study was undertaken to describe the resistance profiles and fluoroquinolone resistance mechanism of Salmonella Typhimurium. RESULTS: The DNA sequence of the gyrA genes from Salmonella enterica serovar typhimurium revealed strong similarity between gyrA and its counterpart in Escherichia coli. The sequencing of quinolone resistance-determining region (QRDR) of the gyrA gene showed the presence of mutation at either S83 or at D87 in almost all the Salmonella typhimurium isolates. CONCLUSION: This mutation, although phenotypically expressed as decreased susceptibility to fluoroquinolones goes undetected by the disk diffusion method using the present method of Kirby-Bauer. Hence, it can increase morbidity and mortality due to delay in appropriate antibiotic treatment.