Psychrotrophic bacteria in Brazilian organic dairy products: identification, production of deteriorating enzymes and biofilm formation

Assessment of the presence of Acinetobacter spp. resistant to β-lactams in commercial ready-to-eat salad samples

Acinetobacter baumannii is a well-known nosocomial infection causing agent. However, other Acinetobacter spp. have also been implicated in cases of human infection. Additionally, these bacteria are known for the development of antibiotic resistance thus making the treatment of the infections they cause, challenging. Due to their relevance in clinical setups less attention has been paid to their presence in foods, and its relation with infection/dissemination routes. In the current study commercial Ready-To-Eat (RTE) salads were analyzed seeking for antibiotic resistant Acinetobacter spp. A preliminary screening allowed us to recover Gram-negative bacteria resistant to β - lactams using cefotaxime, third generation cephalosporins, as the selective agent, and this was followed by identification with CHROMagar™ Acinetobacter and 16S rDNA sequencing. Finally, the isolates identified as Acinetobacter spp. were reanalyzed by PCR to determine the presence of nine potential Extended Spectrum β Lactamases (ESBL). Two commercial RTE salad brands were included in the study (2 batches per brand and 8 samples of each batch making a total of 32 independent samples), and compared against an organic lettuce. High concentrations of β - lactam, resistant bacteria were found in all the samples tested (5 log CFU/g). Additionally, 209 isolates were phenotypically characterized on CHROMagar Acinetobacter. Finally, PCR analysis identified the presence of different ESBL genes, being positive for blaACC, blaSHV, blaDHA and blaVEB; out of these, blaACC was the most prevalent. None of the isolates screened were positive for more than one gene. To conclude, it is important to highlight the fact that pathogenic species within the genus Acinetobacter spp., other than A. baumannii, have been identified bearing resistance genes not typically associated to these microorganisms highlight the importance of continuous surveillance.

Genetic and phenotypical diversity of Pseudomonas syringae population in the Russian Federation

Abstract Proteobacteria comprising species of Pseudomonas syringae group cause diseases of many plants around the world. The phytopathogen has a complex taxonomic structure, which is constantly being revised due to the emergence of new molecular and biochemical diagnostic methods. Here for the first time, we describe the genetic and phenotypic diversity of 57 strains of Pseudomonas syringae isolated from affected soybeans, cereals, sunflowers, and other plants in the Russian Federation from 1950 to 2019. Genetic diversity was assessed by Multi Locus Sequence Analysis (MLSA) using fragments of the genes of glyceraldehyde-3-phosphate dehydrogenase (gapdh), the DNA-directed RNA polymerase subunit D (rpoD), gyrase (topoisomerase) B subunit (gyrB), and citrate synthase I (gltA). The synthesis of syringomycin and coronatine by bacteria was assessed by the reaction of susceptible yeast culture, seedlings of barley, tomato, and sunflower, and by presence of toxin genes confirmed by PCR test. The pathogenicity of the strains was confirmed on seedlings of dicotyledonous and monocotyledonous plants of peas, soybean, sunflowers, barley and wheat, as the most affected crops. The sensitivity of bacteria to 10 antibiotics of the main mechanisms of activity and two bactericidal commercial products was tested by standard disc method. The obtained results showed a high genetic homogeneity of the Russian population of P. syringae, which infects various agricultural crops, and an increase in the proportion of antibiotic-resistant strains over the years.