Green fluorescent protein as a marker for expression of a second gene in transgenic plants.

The use of transgenic crops has generated concerns about transgene movement to unintended hosts and the associated ecological consequences. Moreover, the in-field monitoring of transgene expression is of practical concern (e.g., the underexpression of an herbicide tolerance gene in crop plants that are due to be sprayed with herbicide). A solution to these potential problems is to monitor the presence and expression of an agronomically important gene by linking it to a marker gene, such as GFP. Here we show that GFP fluorescence can indicate expression of the Bacillus thuringiensus cry1Ac gene when co-introduced into tobacco and oilseed rape, as demonstrated by insect bioassays and western blot analysis. Furthermore we conducted two seasons of field experiments to characterize the performance of three different GFP genes in transgenic tobacco. The best gene tested was mGFP5er, a mutagenized GFP gene that is targeted to the endoplasmic reticulum. We also demonstrated that host plants synthesizing GFP in the field suffered no fitness costs.

Prevention of beta-lactam-associated diarrhea by Saccharomyces boulardii compared with placebo.

OBJECTIVES: To determine the safety and efficacy of a new preventive agent for antibiotic-associated diarrhea (AAD) in patients receiving at least one beta-lactam antibiotic. METHODS: A double-blinded, placebo-controlled, parallel group study was performed in a high-risk group of hospitalized patients receiving a new prescription for a beta-lactam antibiotic and having no acute diarrhea on enrollment. Lyophilized Saccharomyces boulardii or placebo (1 g/day) was given within 72 h of the start of the antibiotic(s) and continued until 3 days after the antibiotic was discontinued, after which the patients were followed for 7 wk. RESULTS: Of the 193 eligible patients, significantly fewer, 7/97 (7.2%), patients receiving S. boulardii developed AAD compared with 14/96 (14.6%) on placebo (p = 0.02). The efficacy of S. boulardii for the prevention of AAD was 51%. Using a multivariate model to adjust for two independent risk factors for AAD (age and days of cephalosporin use), the adjusted relative risk was significantly protective for S. boulardii (RR = 0.29, 95% CI = 0.08, 0.98). CONCLUSION: The prophylactic use of S. boulardii given with a beta-lactam antibiotic resulted in a significant reduction of AAD with no serious adverse reactions.

A randomized placebo-controlled trial of Saccharomyces boulardii in combination with standard antibiotics for Clostridium difficile disease.

OBJECTIVE--To determine the safety and efficacy of a new combination treatment for patients with Clostridium difficile-associated disease (CDD). The treatment combines the yeast Saccharomyces boulardii with an antibiotic (vancomycin hydrochloride or metronidazole). DESIGN--A double-blind, randomized, placebo-controlled, parallel-group intervention study in patients with active CDD. Patients received standard antibiotics and S boulardii or placebo for 4 weeks, and were followed up for an additional 4 weeks after therapy. Effectiveness was determined by comparing the recurrence of CDD in the two groups using multivariate analysis to control for other risk factors for CDD. SETTING--National referral study of ambulatory or hospitalized patients from three main study coordinating centers. PATIENTS--A total of 124 eligible consenting adult patients, including 64 who were enrolled with an initial episode of CDD, and 60 who had a history of at least one prior CDD episode. Patients who were immunosuppressed due to acquired immunodeficiency syndrome or cancer chemotherapy within 3 months were not eligible. INTERVENTION--Treatment with oral S boulardii (1 g/d for 4 weeks) or placebo in combination with a standard antibiotic. MAIN OUTCOME MEASURE--Recurrence of active CDD. RESULTS--A history of CDD episodes dramatically increased the likelihood of further recurrences. Multivariate analysis revealed that patients treated with S boulardii and standard antibiotics had a significantly lower relative risk (RR) of CDD recurrence (RR, 0.43; 95% confidence interval, 0.20 to 0.97) compared with placebo and standard antibiotics. The efficacy of S boulardii was significant (recurrence rate 34.6%, compared with 64.7% on placebo; P = .04) in patients with recurrent CDD, but not in patients with initial CDD (recurrence rate 19.3% compared with 24.2% on placebo; P = .86). There were no serious adverse reactions associated with S boulardii. CONCLUSIONS--The combination of standard antibiotics and S boulardii was shown to be an effective and safe therapy for these patients with recurrent CDD; no benefit of S boulardii was demonstrated for those with an initial episode of CDD.

Prevention of catheter-associated urinary tract infection with a silver oxide-coated urinary catheter: clinical and microbiologic correlates.

In a prospective clinical trial involving 482 acutely hospitalized patients, the overall incidence of catheter-associated urinary tract infection (UTI; 10%) was similar in recipients of a silver oxide-coated urinary catheter (silver catheter) or a control silicone catheter. However, female sex and absence of antimicrobial use were independently associated with an increased risk of UTI. After stratification for these variables, the silver catheter reduced the incidence of UTI among women not receiving antimicrobial agents (19% for control catheter vs. 0 for silver catheter, P = .04; confidence interval for the difference in incidence, 0.4%-38%) but not in the other subgroups. Gram-positive UTI was associated with absence of antimicrobial use, the control catheter, and catheter care violations. Gram-negative and candidal UTIs were more common after 7 days of catheterization, and candidal UTI was associated with being female and antimicrobial use. These findings demonstrate that several clinical variables influenced the incidence and microbiology of catheter-associated UTI and that the silver catheter appeared to prevent UTI among women not receiving antimicrobials.