Dataset Information

Sulfamethoxazole - Trimethoprim represses csgD but maintains virulence genes at 30°C in a clinical Escherichia coli O157:H7 isolate.

ABSTRACT: The high frequency of prophage insertions in the mlrA gene of clinical serotype O157:H7 isolates renders such strains deficient in csgD-dependent biofilm formation but prophage induction may restore certain mlrA properties. In this study we used transcriptomics to study the effect of high and low sulfamethoxazole-trimethoprim (SMX-TM) concentrations on prophage induction, biofilm regulation, and virulence gene expression in strain PA20 under environmental conditions following 5-hour and 12-hour exposures in broth or on agar. SMX-TM at a sub-lethal concentration induced strong RecA expression resulting in concentration- and time-dependent major transcriptional shifts with emphasis on up-regulation of genes within horizontally-transferred chromosomal regions (HTR). Neither high or low levels of SMX-TM stimulated csgD expression at either time point, but both levels resulted in slight repression. Full expression of Ler-dependent genes paralleled expression of group 1 pch homologues in the presence of high glrA. Finally, stx2 expression, which is strongly dependent on prophage induction, was enhanced at 12 hours but repressed at five hours, in spite of early SOS initiation by the high SMX-TM concentration. Our findings indicate that, similar to host conditions, exposure to environmental conditions increased the expression of virulence genes in a clinical isolate but genes involved in the protective biofilm response were repressed.

SUBMITTER: Uhlich GA

PROVIDER: S-EPMC5931665 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Sulfamethoxazole - Trimethoprim represses csgD but maintains virulence genes at 30°C in a clinical Escherichia coli O157:H7 isolate.

Uhlich Gaylen A GA Andreozzi Elisa E Cottrell Bryan J BJ Reichenberger Erin R ER Zhang Xinmin X Paoli George C GC

PloS one 20180502 5

The high frequency of prophage insertions in the mlrA gene of clinical serotype O157:H7 isolates renders such strains deficient in csgD-dependent biofilm formation but prophage induction may restore certain mlrA properties. In this study we used transcriptomics to study the effect of high and low sulfamethoxazole-trimethoprim (SMX-TM) concentrations on prophage induction, biofilm regulation, and virulence gene expression in strain PA20 under environmental conditions following 5-hour and 12-hour ...[more]

PMID: 29718957

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Project description:Enterohemorrhagic Escherichia coli (EHEC), including serotype O157:H7, cause severe food-borne illness. On route to the human colon, they encounter and resist, numerous anti-microbial ingestion stresses. We hypothesize that these stresses cue EHEC to alter virulence properties. This study investigated the impact of bile salts on virulence properties and examined the genetic basis of the phenotypes. Established assays were used to examine adhesion to human epithelial cells, motility, verotoxin (VT) production and antimicrobial resistance with/without bile salt stress. Bacteria treated for 90 minute in DMEM plus 0.15% (w/v) bile salt mix demonstrated significantly enhanced adhesion to epithelial cells and resistance to several antibiotics but did not increase motility or VT production. To determine the genetic basis of these phenotypes a microarray experiment was conducted. EHEC strain 86-24, in mid-log phase of growth, were grown in DMEM pH 7.4 (control), or DMEM plus bile salt mix (0.15% w/v), for 90 minutes, statically at 37˚C, 5% CO2 prior to harvesting RNA for the microarray study. Four biological replicates were produced for each treatment. Microarray and gene expression analysis (semi-quantitative RT-PCR and beta-galactosidase reporter assays) of bile salt-treated EHEC revealed significant up-regulation of genes for lipid A modification, fimbriae, an efflux pump, and a two-component regulatory system relative to the bacteria grown in DMEM alone. This work points to several mechanisms that EHEC employs to resist the stresses of the human small intestine, notably efflux, antimicrobial resistance, and outer membrane alterations. Bile salts enhanced the virulence-related properties of increased adhesion and resistance to antimicrobials but not VT production or motility. This research contributes to our understanding of how EHEC senses and responds to host environmental signals and the mechanisms this pathogen uses to successfully colonize and infect the human host.

Project description:Skin and skin-structure infections are common in ambulatory settings. However, the efficacy of various antibiotic regimens in the era of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) is unclear.We enrolled outpatients with uncomplicated skin infections who had cellulitis, abscesses larger than 5 cm in diameter (smaller for younger children), or both. Patients were enrolled at four study sites. All abscesses underwent incision and drainage. Patients were randomly assigned in a 1:1 ratio to receive either clindamycin or trimethoprim-sulfamethoxazole (TMP-SMX) for 10 days. Patients and investigators were unaware of the treatment assignments and microbiologic test results. The primary outcome was clinical cure 7 to 10 days after the end of treatment.A total of 524 patients were enrolled (264 in the clindamycin group and 260 in the TMP-SMX group), including 155 children (29.6%). One hundred sixty patients (30.5%) had an abscess, 280 (53.4%) had cellulitis, and 82 (15.6%) had mixed infection, defined as at least one abscess lesion and one cellulitis lesion. S. aureus was isolated from the lesions of 217 patients (41.4%); the isolates in 167 (77.0%) of these patients were MRSA. The proportion of patients cured was similar in the two treatment groups in the intention-to-treat population (80.3% in the clindamycin group and 77.7% in the TMP-SMX group; difference, -2.6 percentage points; 95% confidence interval [CI], -10.2 to 4.9; P=0.52) and in the populations of patients who could be evaluated (466 patients; 89.5% in the clindamycin group and 88.2% in the TMP-SMX group; difference, -1.2 percentage points; 95% CI, -7.6 to 5.1; P=0.77). Cure rates did not differ significantly between the two treatments in the subgroups of children, adults, and patients with abscess versus cellulitis. The proportion of patients with adverse events was similar in the two groups.We found no significant difference between clindamycin and TMP-SMX, with respect to either efficacy or side-effect profile, for the treatment of uncomplicated skin infections, including both cellulitis and abscesses. (Funded by the National Institute of Allergy and Infectious Diseases and the National Center for Advancing Translational Sciences, National Institutes of Health; ClinicalTrials.gov number, NCT00730028.).

Project description:BACKGROUND:U.S. emergency department visits for cutaneous abscess have increased with the emergence of methicillin-resistant Staphylococcus aureus (MRSA). The role of antibiotics for patients with a drained abscess is unclear. METHODS:We conducted a randomized trial at five U.S. emergency departments to determine whether trimethoprim-sulfamethoxazole (at doses of 320 mg and 1600 mg, respectively, twice daily, for 7 days) would be superior to placebo in outpatients older than 12 years of age who had an uncomplicated abscess that was being treated with drainage. The primary outcome was clinical cure of the abscess, assessed 7 to 14 days after the end of the treatment period. RESULTS:The median age of the participants was 35 years (range, 14 to 73); 45.3% of the participants had wound cultures that were positive for MRSA. In the modified intention-to-treat population, clinical cure of the abscess occurred in 507 of 630 participants (80.5%) in the trimethoprim-sulfamethoxazole group versus 454 of 617 participants (73.6%) in the placebo group (difference, 6.9 percentage points; 95% confidence interval [CI], 2.1 to 11.7; P=0.005). In the per-protocol population, clinical cure occurred in 487 of 524 participants (92.9%) in the trimethoprim-sulfamethoxazole group versus 457 of 533 participants (85.7%) in the placebo group (difference, 7.2 percentage points; 95% CI, 3.2 to 11.2; P<0.001). Trimethoprim-sulfamethoxazole was superior to placebo with respect to most secondary outcomes in the per-protocol population, resulting in lower rates of subsequent surgical drainage procedures (3.4% vs. 8.6%; difference, -5.2 percentage points; 95% CI, -8.2 to -2.2), skin infections at new sites (3.1% vs. 10.3%; difference, -7.2 percentage points; 95% CI, -10.4 to -4.1), and infections in household members (1.7% vs. 4.1%; difference, -2.4 percentage points; 95% CI, -4.6 to -0.2) 7 to 14 days after the treatment period. Trimethoprim-sulfamethoxazole was associated with slightly more gastrointestinal side effects (mostly mild) than placebo. At 7 to 14 days after the treatment period, invasive infections had developed in 2 of 524 participants (0.4%) in the trimethoprim-sulfamethoxazole group and in 2 of 533 participants (0.4%) in the placebo group; at 42 to 56 days after the treatment period, an invasive infection had developed in 1 participant (0.2%) in the trimethoprim-sulfamethoxazole group. CONCLUSIONS:In settings in which MRSA was prevalent, trimethoprim-sulfamethoxazole treatment resulted in a higher cure rate among patients with a drained cutaneous abscess than placebo. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT00729937.).

Dataset Information

Sulfamethoxazole - Trimethoprim represses csgD but maintains virulence genes at 30°C in a clinical Escherichia coli O157:H7 isolate.

Publications

Sulfamethoxazole - Trimethoprim represses csgD but maintains virulence genes at 30°C in a clinical Escherichia coli O157:H7 isolate.

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