Genomic Profile of a Multidrug-Resistant Klebsiella pneumoniae Strain Isolated from a Urine Specimen.

Klebsiella pneumoniae is an opportunistic pathogen mostly found in health care-associated infections but can also be associated with community-acquired infections and is in critical need of new antimicrobial agents for strains resistant to carbapenems. The prevalence of carbapenemase-encoding genes varies among studies. Multidrug-resistant K. pneumoniae strains can harbor several antimicrobial-resistant determinants and mobile genetic elements (MGEs), along with virulence genetic determinants in community settings. We aim to determine the genetic profile of a multidrug-resistant K. pneumoniae strain isolated from a patient with community-acquired UTI. We isolated a K. pneumoniae strain UABC-Str0120, from a urine sample of community-acquired urinary tract infection. Antimicrobial susceptibility tests and Whole-genome sequencing (WGS) were performed. The phylogenetic relationship was inferred by SNPs calling and filtering. UABC-Str0120 showed resistance toward ß-lactams, combinations with ß-lactamase inhibitors, and carbapenems. WGS revealed the presence of genes conferring resistance to aminoglycosides, ß-lactams, carbapenems, quinolones, sulfonamides, phosphonates, phenicols, and quaternary ammonium compounds, 77 subsystems of virulence genes were identified, and an uncommon sequence type ST5889 was also determined. The sequenced strain harbors several MGEs. The UABC-Str0120 recovered from a urine sample harbors several virulence and antimicrobial resistance determinants, which assembles an endangering combination for an immunocompromised or a seemly healthy host, given its presence in a community setting.

Biosynthesis of Silver Nanoparticles Using Seasonal Samples of Sonoran Desert Propolis: Evaluation of Its Antibacterial Activity against Clinical Isolates of Multi-Drug Resistant Bacteria.

Multi-drug resistant (MDR) bacteria have gained importance as a health problem worldwide, and novel antibacterial agents are needed to combat them. Silver nanoparticles (AgNPs) have been studied as a potent antimicrobial agent, capable of countering MDR bacteria; nevertheless, their conventional synthesis methods can produce cytotoxicity and environmental hazards. Biosynthesis of silver nanoparticles has emerged as an alternative to reduce the cytotoxic and environmental problems derived from their chemical synthesis, using natural products as a reducing and stabilizing agent. Sonoran Desert propolis (SP) is a poplar-type propolis rich in polyphenolic compounds with remarkable biological activities, such as being antioxidant, antiproliferative, and antimicrobial, and is a suitable candidate for synthesis of AgNPs. In this study, we synthesized AgNPs using SP methanolic extract (SP-AgNPs) and evaluated the reduction capacity of their seasonal samples and main chemical constituents. Their cytotoxicity against mammalian cell lines and antibacterial activity against multi-drug resistant bacteria were assessed. Quercetin and galangin showed the best-reduction capacity for synthesizing AgNPs, as well as the seasonal sample from winter (SPw-AgNPs). The SPw-AgNPs had a mean size of around 16.5 ± 5.3 nm, were stable in different culture media, and the presence of propolis constituents was confirmed by FT-IR and HPLC assays. The SPw-AgNPs were non-cytotoxic to ARPE-19 and HeLa cell lines and presented remarkable antibacterial and antibiofilm activity against multi-drug resistant clinical isolates, with E. coli 34 and ATCC 25922 being the most susceptible (MBC = 25 µg/mL), followed by E. coli 2, 29, 37 and PNG (MBC = 50 µg/mL), and finally E. coli 37 and S. aureus ATCC 25923 (MBC = 100 µg/mL). These results demonstrated the efficacy of SP as a reducing and stabilizing agent for synthesis of AgNPs and their capacity as an antibacterial agent.

Characterization of Diarreaghenic Escherichia coli Strains Isolated from Healthy Donors, including a Triple Hybrid Strain.

Escherichia coli is a well-recognized inhabitant of the animal and human gut. Its presence represents an essential component of the microbiome. There are six pathogenic variants of E. coli associated with diarrheal processes, known as pathotypes. These harbor genetic determinants that allow them to be classified as such. In this work, we report the presence of diarrheagenic pathotypes of E. coli strains isolated from healthy donors. Ninety E. coli strains were analyzed, of which forty-six (51%) harbored virulence markers specifics for diarrheagenic pathotypes, including four hybrids (one of them with genetic determinants of three DEC pathotypes). We also identified phylogenetic groups with a higher prevalence of B2 (45.6%) and A (17.8%). In addition, resistance to sulfonamides (100%), and aminoglycosides (100%) was found in 100% of the strains, with a lower prevalence of resistance to cefotaxime (13.3%), ceftriaxone (12.2%), fosfomycin (10%), and meropenem (0%). All analyzed strains were classified as multidrug resistant. Virulence genes were also investigated, which led us to propose three new virotypes. Among the virulence traits observed, the ability to form biofilms stands out, which was superior to that of the E. coli and Staphylococcus aureus strains used as positive controls.