Gerardo Aparicio‐Ozores

INTRODUCTION: The increasing prevalence of uropathogenic Escherichia coli (UPEC) strains resistant to multiple antibiotics complicates the treatment of urinary tract infections (UTIs). This study aimed to analyze the antimicrobial resistance, serotypes, and phylogenetic groups among strains of E. coli isolated from outpatients with UTIs in Mexico City. METHODOLOGY: A total of 119 E. coli isolates were recovered from urine samples from outpatients with clinical diagnosis of uncomplicated UTIs from 2004 to 2007. The serotype was assessed by agglutination in microtiter plates; susceptibility to antimicrobials was determined by the disk diffusion method. Clone O25-ST131 and phylogenetic groups of E. coli strains were tested by methods based on PCR multiplex. RESULTS: The predominant serotype was O25:H4 (21.2%). Resistance to antibiotics was ampicillin (83.7%); piperacillin (53.8%); the fluoroquinolone group (55.5-60.6%), and trimethoprim/sulfamethoxazole (TMP/SMX) (56.4%). Additionally, 36 (30.2%) isolates were multidrug-resistant and 13 of these 36 strains were identified as E. coli O25-ST131 clone by an allele-specific PCR-based assay. Phylogenetic analysis showed that 15 of 17 isolates with serotype O25:H4 belonged to group B2. CONCLUSIONS: This is the first report that establishes the presence in Mexico of the O25-ST131 clonal group of E. coli, which has been associated with multidrug-resistance and with high virulence potential. The spread of this clone in Mexico should be monitored closely. We found a correlation between serotype O25:H4 and multidrug resistance in UPEC strains. Our results indicate that the use of ampicillin, fluoroquinolones, and TMP/SMX should be reviewed when selecting empirical therapy for UTIs.

Urinary tract infections (UTIs) are mainly caused by uropathogenic Escherichia coli (UPEC), whose impact can be exacerbated by multidrug-resistant (MDR) strains. Effective control strategies are, therefore, urgently needed. Among them, phage therapy represents a suitable alternative. Here, we describe the isolation and characterization of novel phages from wastewater samples, as well as their lytic activity against biofilm and adherence of UPEC to HEp-2 cells. The results demonstrated that phage vB_EcoM-phiEc1 (ϕEc1) belongs to Myoviridae family, whereas vB_EcoS-phiEc3 (ϕEc3) and vB_EcoS-phiEc4 (ϕEc4) belong to Siphoviridae family. Phages showed lytic activity against UPEC and gut commensal strains. Phage ϕEc1 lysed UPEC serogroups, whereas phages ϕEc3 and ϕEc4 lysed only UTI strains with higher prevalence toward the O25 serogroup. Moreover, phages ϕEc1 and ϕEc3 decreased both biofilm formation and adherence, whereas ϕEc4 was able to decrease adherence but not biofilm formation. In conclusion, these novel phages showed the ability to decrease biofilm and bacterial adherence, making them promising candidates for effective adjuvant treatment against UTIs caused by MDR UPEC strains. KEY POINTS: Phage with lytic activity against MDR UPEC strains were isolated and characterized under in vitro conditions. A novel method was proposed to evaluate phage activity against bacterial adherence in HEp-2 cell.. Phages represent a suitable strategy to control infections caused by MDR bacteria.

BACKGROUND: Some phenolic compounds, such as ferulic acid and p-coumaric acid, exist in the form of free acids, in fruits, rice, corn and other grains. Thermal treatment (121 °C at 15-17 psi) for different times on ferulic, p-coumaric and cinnamic acids as well as equimolar mixtures of these acids was investigated. RESULTS: Ferulic and p-coumaric acids underwent decarboxylation, yielding dimeric products formed through their corresponding radical intermediates, while cinnamic acid was recovered unreacted. High-performance liquid chromatography analysis showed no cross-dimerization when equimolar mixtures of pairs of hydroxycinnamic acids were treated under the same conditions. Dimers were characterized as (E)-4',4″-(but-1-ene-1,3-diyl)bis(2'-methoxyphenol)) (dimer of 4-vinylguaiacol) and (E)-4,4'-(but-1-ene-1,3-diyl)diphenol) (dimer of 4-vinylphenol) by nuclear magnetic resonance and mass spectrometry. CONCLUSION: Sterilization by thermal processing produced dimers of ferulic and coumaric acid. The antioxidant activity of these dimers was greater than that of the respective hydroxycinnamic acids. These results may be relevant for fruits and grains that contain hydroxycinnamic acids and undergo sterilization processes such as canning.

Clostridioides difficile is a global public health problem, which is a primary cause of antibiotic-associated diarrhea in humans. The emergence of hypervirulent and antibiotic-resistant strains is associated with the increased incidence and severity of the disease. There are limited studies on genomic characterization of C. difficile in Latin America. We aimed to learn about the molecular epidemiology and antimicrobial resistance in C. difficile strains from adults and children in hospitals of México. We studied 94 C. difficile isolates from seven hospitals in Mexico City from 2014 to 2018. Whole-genome sequencing (WGS) was used to determine the genotype and examine the toxigenic profiles. Susceptibility to antibiotics was determined by E -test. Multilocus sequence typing (MLST) was used to determine allelic profiles. Results identified 20 different sequence types (ST) in the 94 isolates, mostly clade 2 and clade 1. ST1 was predominant in isolates from adult and children. Toxigenic strains comprised 87.2% of the isolates that were combinations of tcdAB and cdtAB ( tcdA+/tcdB+/cdtA+/cdtB+ , followed by tcdA+/tcdB+/cdtA−/cdtB− , tcdA −/ tcdB+/cdtA−/ cdtB− , and tcdA− / tcdB−/cdtA+/cdtB+ ). Toxin profiles were more diverse in isolates from children. All 94 isolates were susceptible to metronidazole and vancomycin, whereas a considerable number of isolates were resistant to clindamycin, fluroquinolones, rifampicin, meropenem, and linezolid. Multidrug-resistant isolates (≥3 antibiotics) comprised 65% of the isolates. The correlation between resistant genotypes and phenotypes was evaluated by the kappa test. Mutations in rpoB and rpoC showed moderate concordance with resistance to rifampicin and mutations in fusA substantial concordance with fusidic acid resistance. cfrE , a gene recently described in one Mexican isolate, was present in 65% of strains linezolid resistant, all ST1 organisms. WGS is a powerful tool to genotype and characterize virulence and antibiotic susceptibility patterns.