Influence of the Extraction Method on the Polyphenolic Profile and the Antioxidant Activity of Psidium guajava L. Leaf Extracts.

The leaves of Psidium guajava L. are an agro-industrial by-product with an outstanding content of polyphenolic compounds; however, there are many factors which can affect the phytochemical profile when valuing this type of plant material, such as temperatures and extraction times involving in the extraction methods applied. In this context, this study analyzed the impact of different extraction methods (Soxhlet, maceration and ultrasound-assisted extraction) on the phytochemical profile (FTIR and UPLC-MS) and the antioxidant activity (ABTS, FRAP and Folin-Ciocalteu) of guava leaf extracts. A yield of phenolic compounds per gram of guava leaf was obtained within the range of 16 to 45 mg/g; on the other hand, the IC50 values determined with the ABTS assay ranged between 78 ± 4 to 152 ± 12 µg/mL. The methanolic extract obtained by Soxhlet was the one with the best reducing power, both in the FRAP assay and in the Folin-Ciocalteu assay. Finally, bioactive compounds such as quercetin, kaempferol and avicularin were identified in the guava leaf extract. It was concluded that the purification of polyphenolics compounds improves the antioxidant capacity, and that the extraction method greatly influences the phytochemical profile and activity of the extracts.

Biofilm Formation by Escherichia coli Isolated from Urinary Tract Infections from Aguascalientes, Mexico.

Uropathogenic Escherichia coli (UPEC) strains are among the leading causes of urinary tract infections (UTIs) worldwide. They can colonize the urinary tract and form biofilms that allow bacteria to survive and persist, causing relapses of infections and life-threatening sequelae. Here, we analyzed biofilm production, antimicrobial susceptibility, virulence factors, and phylogenetic groups in 74 E. coli isolated from diagnosed patients with UTIs to describe their microbiological features and ascertain their relationship with biofilm capabilities. High levels of ceftazidime resistance are present in hospital-acquired UTIs. Isolates of multidrug resistance strains (p = 0.0017) and the yfcV gene (p = 0.0193) were higher in male patients. All the strains tested were able to form biofilms. Significant differences were found among higher optical densities (ODs) and antibiotic resistance to cefazolin (p = 0.0395), ceftazidime (p = 0.0302), and cefepime (p = 0.0420). Overall, the presence of fimH and papC coincided with strong biofilm formation by UPEC. Type 1 fimbriae (p = 0.0349), curli (p = 0.0477), and cellulose (p = 0.0253) production was significantly higher among strong biofilm formation. Our results indicated that high antibiotic resistance may be related to male infections as well as strong and moderate biofilm production. The ability of E. coli strains to produce biofilm is important for controlling urinary tract infections.

Waterborne pathogens: detection methods and challenges.

Waterborne pathogens and related diseases are a major public health concern worldwide, not only by the morbidity and mortality that they cause, but by the high cost that represents their prevention and treatment. These diseases are directly related to environmental deterioration and pollution. Despite the continued efforts to maintain water safety, waterborne outbreaks are still reported globally. Proper assessment of pathogens on water and water quality monitoring are key factors for decision-making regarding water distribution systems' infrastructure, the choice of best water treatment and prevention waterborne outbreaks. Powerful, sensitive and reproducible diagnostic tools are developed to monitor pathogen contamination in water and be able to detect not only cultivable pathogens but also to detect the occurrence of viable but non-culturable microorganisms as well as the presence of pathogens on biofilms. Quantitative microbial risk assessment (QMRA) is a helpful tool to evaluate the scenarios for pathogen contamination that involve surveillance, detection methods, analysis and decision-making. This review aims to present a research outlook on waterborne outbreaks that have occurred in recent years. This review also focuses in the main molecular techniques for detection of waterborne pathogens and the use of QMRA approach to protect public health.