Association between phenotypic characteristics of Escherichia coli and UTI recurrence in immunocompromised patients: A case-control study.

BACKGROUND: Urinary tract infection (UTI) recurrence is important in immunocompromised patients. There is a trend to study genotypically and phenotypically the role of certain virulence factors of Escherichia coli in the diagnosis of recurrent UTI. The main objective of this study was to determine if there is an association between phenotypic characteristics of E coli and UTI recurrence in immunocompromised patients. METHODS: A case-control study was performed on immunocompromised patients from Hospital Regional de Alta Especialidad del Bajío, Mexico. E coli strains isolated from these patients were identificated and antimicrobial susceptibility test were performed. Strains with filamented cell morphology, mucoid colonial phenotype, or biofilm production were considered cases. Strains without the characteristics were considered controls. UTI recurrence was identified based on clinical records. The odds ratio (OR) was calculated to quantify the magnitude of the association. RESULTS: An association between filamented cell morphology and UTI recurrence was found (OR = 2.19 95% CI 1.06-4.51; P = .031). No association was found between mucoid colony morphology (P>.05) or biofilm production (P>.05) and UTI recurrence. An association between mucoid colony morphology and extended-spectrum ß-lactamase production was found (OR = 3.09 95% 1.59-5.99; P<.001). CONCLUSIONS: Filamented cell morphology and mucoid colonial phenotype may have a possible diagnostic value for the detection of UTI recurrence and antimicrobial resistance. Further diagnostic test studies are needed to fully assess their clinical utility.

Purification of bacterial genomic DNA in less than 20 min using chelex-100 microwave: examples from strains of lactic acid bacteria isolated from soil samples.

We established a Chelex 100-Microwave method for the purification of bacterial genomic DNA (gDNA) in less than 20 min with high yield and good quality, useful for multiple purposes. It combines Chelex 100, proteinase K, RNase A and heating in a microwave oven. The resulting gDNA was used directly to identify bacterial species of the Order Lactobacillales by means of PCR amplification of their 16S rDNA gene, isolated from sediments on the Yucatan Peninsula, Mexico. This method produced gDNA free of phenolic and protein residual contaminants from 100 of these isolated bacteria. 16S rDNA amplification and sequencing showed Pediococcus acidilactici to prevail in inland lagoons, and Pediococcus pentosaceus, Lactobacillus plantarum, Lactobacillus sp., and Lactobacillus fermentum to be most abundant in the soils of livestock farms. The combination of Chelex 100, enzymes and microwave heating used in the Chelex 100-Microwave method produced large amounts of highly pure gDNA from Gram-positive and Gram-negative bacteria, in less than 20 min.