Risk factors for faecal carriage of multidrug-resistant Escherichia coli in a college community: a penalised regression model.

OBJECTIVES: Bacterial antimicrobial resistance is a serious global public-health threat. Intestinal commensal drug-resistant bacteria have been suggested as an important reservoir of antimicrobial resistance genes (ARGs), which may be acquired via food. We aimed to identify risk factors associated with faecal carriage of drug-resistant commensal Escherichia coli among healthy adults focused on their dietary habits. METHODS: We conducted a cross-sectional study targeting healthy adult volunteers in a college community. Faecal samples and questionnaires were obtained from 113 volunteers. We conducted backward elimination logistic regression and least absolute shrinkage and selection operator (LASSO) methods to identify risk factors. RESULTS: We analysed responses from 81 of 113 volunteers who completed the questionnaire. The logistic regression and LASSO methods identified red meat consumption to be associated with an increased risk [OR = 6.13 (95% CI 1.83-24.2) and 1.82, respectively] and fish consumption with a reduced risk [OR = 0.27 (95% CI 0.08-0.85) and 0.81] for carriage of multidrug-resistant (MDR) E. coli, adjusted for biological sex, employment status, frequently used supermarket and previous travel. CONCLUSION: Dietary habits are associated with risk of faecal carriage of MDR E. coli. This study supports the growing evidence that food may be an important source of ARGs present in human commensal E. coli.

Prevalence of Antimicrobial Resistance Genes and Integrons in Commensal Gram-Negative Bacteria in a College Community.

Although the human intestinal microbiome has been shown to harbor antimicrobial drug resistance genes (ARGs), the prevalence of such genes in a healthy population and their impact on extraintestinal infections that occur in that community are not well established. This study sought to identify ARG prevalence and their mobile elements in the intestines of a healthy community population at a California University, and compared these genes to those previously identified among uropathogenic Escherichia coli isolated from patients with urinary tract infection from the same community. We isolated Gram-negative bacteria (GNB) from fecal samples of healthy volunteers and screened them by polymerase chain reaction for class 1 integron cassette sequences and ARGs encoding resistance against ampicillin, trimethoprim-sulfamethoxazole, gentamicin, and colistin. We found antimicrobial-resistant GNB from 83 (81%) of 102 nonredundant rectal swab samples. Seventy-four (72%) of these samples contained ß-lactamase genes (blaTEM, blaSHV, blaCTX-M, blaOXA, and blaOXY), dihydrofolate reductase (DHFR) genes (dhfr-A17, dhfr-A12, dhfr-A7, dhfr-A5, dhfr-A21, dhfr-A1, dhfr-A13, and dhfr-7), and aminoglycoside resistance genes (aadA5, aadA2, aadA1, and aadB). Integron sequences were found in 37 (36%) fecal samples. These genes were found in 11 different GNB species. The high prevalence of clinically common ARGs and integrons harbored by GNB in the intestine of a healthy population suggest that human intestines may serve as a major reservoir of these mobile ARGs that appear in E. coli strains causing extraintestinal infections in the same community.

Cationic ionic liquid surfactant-polyacrylamide gel electrophoresis for enhanced separation of acidic and basic proteins with single-step ribonuclease b glycoforms separation.

Cationic ionic liquids-based surfactants (ILS), such as 4-methyl pyridinium bromide (CnPBr, where n=4,6,8), were used in preparation of polyacrylamide gels, sample buffer, and running buffer for cationic ILS polyacrylamide gel electrophoresis (ILS-PAGE). These ILS are liquids in the pure state and were selected for improved separation of ribonuclease b (Rib b) glycoforms in a single step and a protein mixture containing bovine serum albumin (BSA, pI-4.8, 66.5kDa), ovalbumin (Ova, pI-4.6, 44.3kDa), α-chymotrypsinogen (α-Chy, pI-8.8, 25.7kDa), myoglobin (Myo, pI-6.8, 16.9kDa), and cytochrome c (Cyt c, pI-10.0, 12.3kDa). Results acquired for Rib b glycoform separation by use of ILS were compared with conventional non-ILS surfactants-PAGE: sodium dodecylsulfate (SDS)-PAGE, cetyltrimethylammonium bromide (CTAB)-PAGE, and benzyldimethyl-n-hexadecylammonium chloride (16-BAC)-PAGE. A single protein band was observed with relatively short migration time in all the conventional PAGE techniques tested. In contrast, ILS-PAGE showed multiple bands with two distinct bands for Rib b protein. The two distinct bands of Rib b from ILS-PAGE were further analyzed using MALDI-MS. Examination of MALDI-MS spectral data revealed the presence of Rib b glycoforms. Furthermore, a two-dimensional isoelectric focusing (IEF)/SDS-PAGE map of Rib b protein revealed negative charge heterogeneity on the protein, which is a common observation for glycoproteins. This overall discovery greatly enhances the capability of using cationic ILS-PAGE for Rib b protein separation. Among all ILS tested, excellent protein separations were observed using C4PBr ILS at concentrations of 0.05% (w/v) in polyacrylamide gels, 0.01% (w/v) in protein sample buffer, and 0.1% (w/v) in running buffer. Under these optimum conditions, all other tested proteins were separated as sharp bands with good resolution.