***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The epidemiology , clinical severity , and case-fatality ratio of Clostridium difficile infection ( CDI ) changed dramatically with the emergence of a toxin hyperproducing strain ( BI/NAP1/027 ) in North America and Europe in 2000 . For the treatment of CDI , metronidazole and vancomycin remain the 2 most commonly used drugs . The 3 r and omized controlled trials published thus far , as well as the upcoming tolevamer trial , use intermediate outcomes , rather than the outcomes that now preoccupy clinicians : the frequency of complications or recurrence . The major advantage of metronidazole is its low price . The major advantage of orally administered vancomycin is its more favorable pharmacokinetics . Facilitating vancomycin-resistant enterococci colonization and /or infection is a potential drawback of both drugs . Pending the development of a prospect ively vali date d scoring system , members of the Infectious Diseases Society of America/Society for Healthcare Epidemiology of America expert committee will define severe CDI as present in any patient with a  leukocyte count  > or = 15,000 cells/mm(3 ) or a creatinine level increased by > or = 50 % from baseline . For patients with mild-to-moderate CDI ( defined by a leukocyte count < 15000 cells/mm(3 ) and a creatinine level < 1.5 times the baseline value ) , there is no evidence that treatment with vancomycin is superior to treatment with metronidazole ( even for intermediate outcomes ) , and metronidazole therapy should be preferred . For patients with severe CDI who are not infected with BI/NAP1/027 , there is reasonable evidence that the better pharmacokinetics of vancomycin translate into a lower probability of complications . For those patients who are infected with BI/NAP1/027 , the superiority of vancomycin therapy remains to be proven . In practice , because it is not yet possible to rapidly type the strains , all patients with severe CDI should be treated with  vancomycin .  Future trials should use complicated CDI and recurrences as their primary outcomes BACKGROUND Clostridium difficile colitis has increased in incidence and severity , and treatment failure with metronidazole therapy has increasingly been documented . It is uncertain whether treatment with vancomycin is more effective than treatment with metronidazole , but concern over the emergence of vancomycin resistance has motivated the search for alternative therapy . Nitazoxanide , a nitrothiazolide , blocks anaerobic metabolism of eukaryocyes and effectively treats intestinal infestation due to Cryptosporidium or Giardia species . At low concentrations , this compound inhibits C. difficile in vitro . METHODS We design ed a prospect i ve , r and omized , double-blind study to compare nitazoxanide to metronidazole in treating hospitalized patients with C. difficile colitis . RESULTS Thirty-four patients received metronidazole at a dosage of 250 mg 4 times per day for 10 days , 40 patients received nitazoxanide at a dosage of 500 mg 2 times per day for 7 days , and 36 patients received nitazoxanide at a dosage of 500 mg 2 times per day for 10 days . After 7 days of treatment , 28 ( 82.4 % ) of 34 patients had responded to metronidazole therapy , compared with 68 ( 89.5 % ) of 76 who had received nitazoxanide therapy ( difference , 7.1 % ; 95 % confidence interval , -7.1 % to 25.5 % ) . Thirty-one days after beginning treatment , sustained responses were observed in 19 ( 57.6 % ) of 33 patients who had received metronidazole therapy for 10 days , compared with 25 ( 65.8 % ) of 38 who had received nitazoxanide for 7 days and 26 ( 74.3 % ) of 35 who had received nitazoxanide for 10 days ( P = .34 ) . CONCLUSION Nitazoxanide is at least as effective as metronidazole in treating C. difficile colitis The efficacy of vancomycin in pseudomembranous colitis was assessed in a prospect i ve r and omised controlled trial . Forty-four patients with postoperative diarrhoea were allocated to five days ' treatment with either 125 mg vancomycin six-hourly or a placebo .  Sixteen patients had high titres of the neutralised faecal toxin characteristic of pseudomembranous colitis ; nine received vancomycin  and seven  placebo .  At the end of treatment faecal toxins were present in one patient given vancomycin compared with five of the controls . Vancomycin caused the disappearance of Clostridum difficile from the stool in all except one patient , whereas toxicogenic strains of Cl difficile persisted in all but one of the controls . Histological evidence of psuedomembranous colitis had disappeared by the end of treatment in six out of seven patients given vancomycin compared with only one out of seven patients given vancomycin compared with only one out of five patients given placebo . In patients with faecal toxins  bowel habit had returned to normal in seven of the vancomycin group compared with only one of the controls , but there was no significant difference in clinical response among patients without faecaal toxins . The results suggest that vancomycin eliminates toxin-producing Cl difficile from the colon and is associated with rapid clinical and histological improvement in patients with pseudomembranous colitis The effectiveness of a ten-day course of either oral bacitracin or oral vancomycin hydrochloride for treatment of  Clostridium difficile-induced antibiotic-associated diarrhea  was compared in a r and omized double-blind study . Bacitracin was as effective as vancomycin in resolving diarrhea ; most patients responded within five days of therapy with either drug . Three patients receiving bacitracin  worsened during therapy ; two of these were considered treatment failures . Neither C difficile nor its toxin was detected in stool sample s collected on the final day of therapy in 71 % of patients ( 10/14 ) receiving vancomycin  and in 30 % ( 3/10 ) receiving bacitracin . Five patients receiving  bacitracin and three receiving vancomycin had at least one recurrence . Low but nontoxic concentrations of bacitracin  were detected in serum sample s collected from 11 patients . Oral bacitracin at this dosage level was as effective as vancomycin in resolving the symptoms of C difficile-induced antibiotic-associated diarrhea in most patients but was less effective in eradicating C difficile and its toxin from patients ' stools BACKGROUND Clostridium difficile infection is a serious diarrheal illness associated with substantial morbidity and mortality . Patients generally have a response to oral vancomycin or metronidazole ; however , the rate of recurrence is high . This phase 3 clinical trial compared the efficacy and safety of fidaxomicin with those of vancomycin in treating C. difficile infection . METHODS Adults with acute symptoms of C. difficile infection and a positive result on a stool toxin test were eligible for study entry . We r and omly assigned patients to receive fidaxomicin ( 200 mg twice daily ) or vancomycin ( 125 mg four times daily ) orally for 10 days . The primary end point was clinical cure ( resolution of symptoms and no need for further therapy for C. difficile infection as of the second day after the end of the course of therapy ) . The secondary end points were recurrence of C. difficile infection ( diarrhea and a positive result on a stool toxin test within 4 weeks after treatment ) and global cure ( i.e. , cure with no recurrence ) . RESULTS A total of 629 patients were enrolled , of whom 548 ( 87.1 % ) could be evaluated for the per- protocol analysis . The rates of clinical cure with fidaxomicin were noninferior to those with vancomycin in both the modified intention-to-treat analysis ( 88.2 % with fidaxomicin and 85.8 % with vancomycin ) and the per- protocol analysis ( 92.1 % and 89.8 % , respectively ) . Significantly fewer patients in the fidaxomicin group than in the vancomycin group had a recurrence of the infection , in both the modified intention-to-treat analysis ( 15.4 % vs. 25.3 % , P=0.005 ) and the per- protocol analysis ( 13.3 % vs. 24.0 % , P=0.004 ) . The lower rate of recurrence was seen in patients with non – North American Pulsed Field type 1 strains . The adverse-event profile was similar for the two therapies . CONCLUSIONS The rates of clinical cure after treatment with fidaxomicin were noninferior to those after treatment with vancomycin . Fidaxomicin was associated with a significantly lower rate of recurrence of C. difficile infection associated with non – North American Pulsed Field type 1 strains . ( Funded by Optimer Pharmaceuticals ; Clinical Trials.gov number , NCT00314951 . PURPOSE High-dose ( 500 mg orally four times daily ) vancomycin is considered by many investigators to be the most effective treatment for antibiotic-associated Clostridium difficile colitis . However , a lower dosage of 125 or 150 mg given three or four times a day has become popular , has been shown to be effective , and is less expensive than the high-dose regimen . We therefore decided to compare two vancomycin dosage regimens in a r and omized trial . PATIENTS AND METHODS The study involved 46 hospitalized patients with serious underlying diseases complicated by C. difficile diarrhea or colitis . Patients were assigned ( according to a table of r and om numbers ) to treatment with either 125 or 500 mg of vancomycin orally four times daily for an average of 10 days . RESULTS No significant differences in measurable responses to the two regimens were noted . There were no treatment failures . The mean duration of diarrhea after initiation of therapy was about four days , and almost all patients had no diarrhea after one week . The organism continued to be demonstrated in the stools of about 50 percent of patients for the first few weeks after completion of therapy , and nine ( 20 percent ) patients developed a recurrence of their diarrheal illness .  Vancomycin was well tolerated by all patients . CONCLUSION Since the dose of 125 mg appeared to be as effective as the 500-mg dose , which is more expensive , the 125-mg dose is preferred when vancomycin is used in treatment of this disease , unless the patient is critically ill BACKGROUND The incidence and severity of Clostridium difficile-associated diarrhea ( CDAD ) has been increasing , and there have been recent reports of metronidazole treatment failure . Metronidazole is still commonly used as first-line treatment for CDAD but has never been compared with vancomycin in a prospect i ve , r and omized , double-blind , placebo-controlled trial . We conducted such a trial , stratifying patients according to disease severity , to investigate whether one agent was superior for treating either mild or severe disease . METHODS From October 1994 through June 2002 , patients with CDAD were stratified according to whether they had mild or severe disease based on clinical criteria and were r and omly assigned to receive oral metronidazole ( 250 mg 4 times per day ) or oral vancomycin ( 125 mg 4 times per day ) for 10 days . Both groups received an oral placebo in addition to the study drug . Patients were followed up for 21 days to assess cure , treatment failure , relapse , or intolerance . RESULTS One hundred seventy-two patients were enrolled , and 150 of these patients successfully completed the trial . Among the patients with mild CDAD , treatment with metronidazole or vancomycin result ed in clinical cure in 90 % and 98 % of the patients , respectively ( P=.36 ) . Among the patients with severe CDAD , treatment with metronidazole or vancomycin result ed in clinical cure in 76 % and 97 % of the patients , respectively ( P=.02 ) . Clinical symptoms recurred in 15 % of the patients treated with metronidazole and 14 % of those treated with vancomycin . CONCLUSIONS Our findings suggest that metronidazole and vancomycin are equally effective for the treatment of mild CDAD , but vancomycin is superior for treating patients with severe CDAD ABSTRACT For treatment of mild to moderate Clostridium difficile-associated disease ( CDAD ) , oral metronidazole has been recommended as the preferred agent , in part due to concern that vancomycin may be more likely to promote colonization by vancomycin-resistant enterococci ( VRE ) . We performed a prospect i ve observational study to examine the effects of oral metronidazole or vancomycin treatment of CDAD on acquisition and concentration of VRE stool colonization . Before , during , and after 90 courses of CDAD therapy , stool sample s were cultured for VRE , and the concentrations were quantified . Eighty-seven subjects ( 97 % ) had received antibiotics within the past month . For 56 treatment courses in which preexisting VRE colonization was present , metronidazole ( n = 37 courses ) and vancomycin ( n = 19 courses ) , each promoted persistent 
    Output:
    
Harms , when reported , did not differ between treatments in any study .
No antimicrobial agent is clearly superior for the initial cure of C. difficile infection .
Recurrence is less frequent with fidaxomicin than with vancomycin .