Mechanisms and management of antibiotic-associated diarrhea

Association of beta2 toxin production withClostridium perfringenstype A human gastrointestinal disease isolates carrying a plasmid enterotoxin gene

Clostridium perfringens type A isolates carrying an enterotoxin (cpe) gene are an important cause of human gastrointestinal diseases, including food poisoning, antibiotic-associated diarrhoea (AAD) and sporadic diarrhoea (SD). Using polymerase chain reaction (PCR), the current study determined that the cpb2 gene encoding the recently discovered beta2 toxin is present in <15% of food poisoning isolates, which typically carry a chromosomal cpe gene. However, >75% of AAD/SD isolates, which usually carry a plasmid cpe gene, tested cpb2(+) by PCR. Western blot analysis demonstrated that >97% of those cpb2(+)/cpe(+) AAD/SD isolates can produce CPB2. Additional PCR analyses, sequencing studies and pulsed field gel electrophoresis experiments determined that AAD/SD isolates carry cpb2 and cpe on the same plasmid when IS1151 sequences are present downstream of cpe, but cpb2 and cpe are located on different plasmids in AAD/SD isolates where IS1470-like sequences are present downstream of cpe. Those analyses also demonstrated that two different CPB2 variants (named CPB2h1 or CPB2h2) can be produced by AAD/SD isolates, dependent on whether IS1470-like or IS1151 sequences are present downstream of their cpe gene. CPB2h1 is approximately 10-fold more cytotoxic for CaCo-2 cells than is CPB2h2. Collectively, these results suggest that CPB2 could be an accessory toxin in C. perfringens enterotoxin (CPE)-associated AAD/SD.

Candida and antibiotic-associated diarrhoea

The role of Candida in antibiotic-associated diarrhoea (AAD) has been controversial for many years. Since Candida exists physiologically in the gastrointestinal tract, the presence of small numbers of Candida organisms in stool has therefore been considered normal, and thus non-pathogenic. Increased Candida counts have been linked to the development of diarrhoea in antibiotic-treated patients. However, recent findings have not confirmed this. To date, there is no convincing evidence that Candida may cause AAD in adults.

Antimicrobial evaluation of some medicinal plants for their anti-enteric potential against multi-drug resistantSalmonella typhi

Screening was done of some plants of importance in the Ayurvedic system of traditional medicine used in India to treat enteric diseases. Fifty four plant extracts (methanol and aqueous) were assayed for their activity against multi-drug resistant Salmonella typhi. Strong antibacterial activity was shown by the methanol extracts of Aegle marmelos, Salmalia malabarica, Punica granatum, Myristica fragrans, Holarrhena antidysenterica, Terminalia arjuna and Triphal (mixture of Emblica of fi cinalis, Terminalia chebula and Terminalia belerica). Moderate antimicrobial activity was shown by Picorhiza kurroa, Acacia catechu, Acacia nilotica, Cichorium intybus, Embelia ribes, Solanum nigrum, Carum copticum, Apium graveolens, Ocimum sanctum, Peucedanum graveolens and Butea monosperma.

Clostridium difficile-associated diarrhea in a region of Quebec from 1991 to 2003: a changing pattern of disease severity

BACKGROUND

Recent reports suggest that Clostridium difficile colitis may be evolving into a more severe disease. During the second half of 2002 we noted an increase in the number of patients with severe C. difficile-associated diarrhea (CDAD) in our institution. We describe cases of CDAD at our institution over a 13-year period and investigate changes in illness severity.

METHODS

We undertook a retrospective chart review of all cases of CDAD diagnosed at the Centre hospitalier universitaire de Sherbrooke from Jan. 1, 1991, to Dec. 31, 2003. Because the hospital serves a well-defined population of Quebec, we were also able to calculate population-based incidence during this period. We abstracted data on individual patients from patient charts and from hospital and pharmacy computer databases. We defined cases of CDAD as having a positive C. difficile cytotoxicity assay result, or endoscopic or histopathological evidence of pseudomembranous colitis. A case was considered complicated if one or more of the following was observed: megacolon, perforation, colectomy, shock requiring vasopressor therapy, or death within 30 days after diagnosis.

RESULTS

A total of 1721 cases of CDAD were diagnosed during the study period. The incidence increased from 35.6 per 100,000 population in 1991 to 156.3 per 100,000 in 2003; among patients aged 65 years or more, it increased from 102.0 to 866.5 per 100,000. The proportion of cases that were complicated increased from 7.1% (12/169) in 1991-1992 to 18.2% (71/390) in 2003 (p < 0.001), and the proportion of patients who died within 30 days after diagnosis increased from 4.7% (8/169) in 1991-1992 to 13.8% (54/390) in 2003 (p < 0.001). A high leukocyte count (20.0 small ha, Cyrillic 10(9)/L or greater) and an elevated creatinine level (200 micromol/L or greater) were strongly associated with adverse outcomes: in 2003, 45 (40.9%) of 110 patients with a high leukocyte count or creatinine level, or both, had complicated CDAD and 28 (25.5%) died within 30 days after diagnosis. After adjustment for age and other confounding factors, patients initially given oral vancomycin therapy had a risk of progression to complicated CDAD that was 79% lower than the risk among patients initially treated with metronidazole (adjusted odds ratio 0.2, 95% confidence interval 0.06-0.8, p = 0.02).

INTERPRETATION

An epidemic of CDAD with an increased case-fatality rate has had important consequences on the elderly population of our region. Our observational data suggest that the equivalence of vancomycin and metronidazole in the treatment of CDAD needs to be questioned.

Effects of Clostridium perfringens alpha-toxin (PLC) and perfringolysin O (PFO) on cytotoxicity to macrophages, on escape from the phagosomes of macrophages, and on persistence of C. perfringens in host tissues

Clostridium perfringens is the most common cause of clostridial myonecrosis (gas gangrene). Polymorphonuclear cells (PMNs) appear to play only a minor role in preventing the onset of myonecrosis in a mouse animal model of the disease (unpublished results). However, the importance of macrophages in the host defense against C. perfringens infections is still unknown. Two membrane-active toxins produced by the anaerobic C. perfringens, alpha-toxin (PLC) and perfringolysin O (PFO), are thought to be important in the pathogenesis of gas gangrene and the lack of phagocytic cells at the site of infection. Therefore, C. perfringens mutants lacking PFO and PLC were examined for their relative cytotoxic effects on macrophages, their ability to escape the phagosome of macrophages, and their persistence in mouse tissues. C. perfringens survival in the presence of mouse peritoneal macrophages was dependent on both PFO and PLC. PFO was shown to be the primary mediator of C. perfringens-dependent cytotoxicity to macrophages. Escape of C. perfringens cells from phagosomes of macrophage-like J774-33 cells and mouse peritoneal macrophages was mediated by either PFO or PLC, although PFO seemed to play a more important role in escape from the phagosome in peritoneal macrophages. At lethal doses (10(9)) of bacteria only PLC was necessary for the onset of myonecrosis, while at sublethal doses (10(6)) both PFO and PLC were necessary for survival of C. perfringens in mouse muscle tissue. These results suggest PFO-mediated cytotoxicity toward macrophages and the ability to escape macrophage phagosomes may be important factors in the ability of C. perfringens to survive in host tissues when bacterial numbers are low relative to those of phagocytic cells, e.g., early in an infection.

Clostridium difficile-associated diarrhea in a region of Quebec from 1991 to 2003: a changing pattern of disease severity

BACKGROUND

Recent reports suggest that Clostridium difficile colitis may be evolving into a more severe disease. During the second half of 2002 we noted an increase in the number of patients with severe C. difficile-associated diarrhea (CDAD) in our institution. We describe cases of CDAD at our institution over a 13-year period and investigate changes in illness severity.

METHODS

We undertook a retrospective chart review of all cases of CDAD diagnosed at the Centre hospitalier universitaire de Sherbrooke from Jan. 1, 1991, to Dec. 31, 2003. Because the hospital serves a well-defined population of Quebec, we were also able to calculate population-based incidence during this period. We abstracted data on individual patients from patient charts and from hospital and pharmacy computer databases. We defined cases of CDAD as having a positive C. difficile cytotoxicity assay result, or endoscopic or histopathological evidence of pseudomembranous colitis. A case was considered complicated if one or more of the following was observed: megacolon, perforation, colectomy, shock requiring vasopressor therapy, or death within 30 days after diagnosis.

RESULTS

A total of 1721 cases of CDAD were diagnosed during the study period. The incidence increased from 35.6 per 100,000 population in 1991 to 156.3 per 100,000 in 2003; among patients aged 65 years or more, it increased from 102.0 to 866.5 per 100,000. The proportion of cases that were complicated increased from 7.1% (12/169) in 1991-1992 to 18.2% (71/390) in 2003 (p < 0.001), and the proportion of patients who died within 30 days after diagnosis increased from 4.7% (8/169) in 1991-1992 to 13.8% (54/390) in 2003 (p < 0.001). A high leukocyte count (20.0 small ha, Cyrillic 10(9)/L or greater) and an elevated creatinine level (200 micromol/L or greater) were strongly associated with adverse outcomes: in 2003, 45 (40.9%) of 110 patients with a high leukocyte count or creatinine level, or both, had complicated CDAD and 28 (25.5%) died within 30 days after diagnosis. After adjustment for age and other confounding factors, patients initially given oral vancomycin therapy had a risk of progression to complicated CDAD that was 79% lower than the risk among patients initially treated with metronidazole (adjusted odds ratio 0.2, 95% confidence interval 0.06-0.8, p = 0.02).

INTERPRETATION

An epidemic of CDAD with an increased case-fatality rate has had important consequences on the elderly population of our region. Our observational data suggest that the equivalence of vancomycin and metronidazole in the treatment of CDAD needs to be questioned.

The CcpA protein is necessary for efficient sporulation and enterotoxin gene (cpe) regulation in Clostridium perfringens

Clostridium perfringens is the cause of several human diseases, including gas gangrene (clostridial myonecrosis), enteritis necroticans, antibiotic-associated diarrhea, and acute food poisoning. The symptoms of antibiotic-associated diarrhea and acute food poisoning are due to sporulation-dependent production of C. perfringens enterotoxin encoded by the cpe gene. Glucose is a catabolite repressor of sporulation by C. perfringens. In order to identify the mechanism of catabolite repression by glucose, a mutation was introduced into the ccpA gene of C. perfringens by conjugational transfer of a nonreplicating plasmid into C. perfringens, which led to inactivation of the ccpA gene by homologous recombination. CcpA is a transcriptional regulator known to mediate catabolite repression in a number of low-G+C-content gram-positive bacteria, of which C. perfringens is a member. The ccpA mutant strain sporulated at a 60-fold lower efficiency than the wild-type strain in the absence of glucose. In the presence of 5 mM glucose, sporulation was repressed about 2,000-fold in the wild-type strain and 800-fold in the ccpA mutant strain compared to sporulation levels for the same strains grown in the absence of glucose. Therefore, while CcpA is necessary for efficient sporulation in C. perfringens, glucose-mediated catabolite repression of sporulation is not due to the activity of CcpA. Transcription of the cpe gene was measured in the wild-type and ccpA mutant strains grown in sporulation medium by using a cpe-gusA fusion (gusA is an Escherichia coli gene encoding the enzyme beta-glucuronidase). In the exponential growth phase, cpe transcription was two times higher in the ccpA mutant strain than in the wild-type strain. Transcription of cpe was highly induced during the entry into stationary phase in wild-type cells but was not induced in the ccpA mutant strain. Glucose repressed cpe transcription in both the wild-type and ccpA mutant strain. Therefore, CcpA appears to act as a repressor of cpe transcription in exponential growth but is required for efficient sporulation and cpe transcription upon entry into stationary phase. CcpA was also required for maximum synthesis of collagenase (kappa toxin) and acted as a repressor of polysaccharide capsule synthesis in the presence of glucose, but it did not regulate synthesis of the phospholipase PLC (alpha toxin).

Probiotics in relapsing and chronic diarrhea

Diarrhea is common in oncology patients; if it becomes chronic and relapsing, it can be debilitating, hinder planned management, and be difficult to treat. The authors describe two patients, one with leukemia who developed recurrent Clostridium difficile colitis and another who developed chronic diarrhea after bone marrow transplantation. In both patients, administration of antibiotics was suspected as the cause. In one patient, relapsing diarrhea resolved after probiotics were given with a 2-day course of metronidazole, and in the other patient, chronic diarrhea resolved after probiotics were given; resolution was maintained after the probiotics were stopped. Probiotics may offer a way to bring about resolution in antibiotic-associated chronic diarrhea.

Antibiotic-associated diarrhea accompanied by large-scale alterations in the composition of the fecal microbiota

Alterations in the diversity of the gut microbiota are believed to underlie the development of antibiotic-associated diarrhea (AAD). A molecular phylogenetic analysis was performed to document temporal changes in the diversity of fecal bacteria of a patient who developed AAD. Antibiotic administration was associated with distinct changes in the diversity of the gut microbiota, including a marked decrease in the prevalence of butyrate-producing bacteria. Following the discontinuation of the antibiotic, resolution of diarrhea was accompanied by a reversal of these changes, providing the first direct evidence linking changes in the community structure of the gastrointestinal bacteria with the development of AAD.

Microbial-gut interactions in health and disease. Antibiotic-associated diarrhoea

Most cases of antibiotic-associated diarrhoea (AAD) are directly or indirectly due to the alteration of gut microflora by antibiotics. 'Functional' diarrhoea, usually limited to a mild and brief change in stool frequency, is considered as the most frequent pattern of AAD. Reduced carbohydrate fermentation and impaired metabolism of bile acids have been claimed as the potential causes of this transient digestive discomfort but a critical analysis of the data supporting these theories is necessary. Alternatively, changes in the gut flora ecosystem allow pathogens to proliferate. Clostridium difficile is responsible for approximately 10% of cases of AAD and almost all cases of antibiotic-associated pseudomembranous colitis. The level of evidence which supports the potential responsibility of other candidate pathogens (Klebsiella oxytoca, enterotoxin-producing Clostridium perfringens and Staphylococcus aureus, Candida) needs to be appreciated according to the updated postulates of causality relationships between a bacterium and a disease.

Diarrhoea in children: an interface between developing and developed countries

Despite much progress in the understanding of pathogenesis and of management, diarrhoeal illnesses remain one of the most important causes of global childhood mortality and morbidity. Infections account for most illnesses, with pathogens employing ingenious mechanisms to establish disease. In the developed world, an upsurge in immune-mediated gut disorders might have resulted from a disruption of normal bacterial-epithelial cross-talk and impaired maturation of the gut's immune system. Oral rehydration therapies are the mainstay of management of gastroenteritis, and their composition continues to improve. Malnutrition remains the major adverse prognostic indicator for diarrhoea-related mortality, emphasising the importance of nutrition in early management. Drugs are of little use, except for specific indications although new agents that target mechanisms of secretory diarrhoea show promise, as do probiotics. However, preventive strategies on a global scale might ultimately hold the greatest potential to reduce the burden of diarrhoeal disease. These strategies include vaccines and, most importantly, policies to address persisting inequalities between the developed and developing worlds with respect to nutrition, sanitation, and access to safe drinking water.

Diarrhées associées aux antibiotiques chez le sujet âgé

PURPOSE

Most of the antibiotic-associated diarrhea (AAD) cases result from a transient disturbance in the function of the normal intestinal flora and are spontaneously solved when discontinuing the antibacterial therapy. However, a mild diarrhea lasting several days may induce a dehydration or worsen a denutrition in frail elderly people.

CURRENT KNOWLEDGE AND KEY POINTS

The incidence of AAD varies between 5 and 25% depending on the concerned antibiotic. Only 10-20% of all AAD cases are caused by infection, especially with Clostridium difficile, for which advanced age is a major risk factor. The first biological exam to perform when severe AAD or in frail people is the detection of C. difficile toxins, especially in elderly patient treated with beta-lactam antibiotics. Nevertheless, other infectious organisms causing AAD may be considered, as Staphylococcus aureus when predominant in stool cultures from patients treated with fluoroquinolones or as Klebsiella oxytoca when isolated in bloody diarrhea from patients treated with ampicillin. Elevated fecal counts of Candida spp. found in patients treated with antibiotics is rather the consequence of therapy than the cause of AAD. The prevention of AAD is based on a rational antibiotic use to avoid endogenous selection of C. difficile and on the improvement of the hygiene measures to limit the exogenous transmission of the bacteria or related spores by spoiled hands.

FUTURE PROSPECTS

Simultaneous prescription of non-pathogenic living organisms, capable of re-establishing the equilibrium of the intestinal flora, should be better described, especially in elderly people, because of its important economic impact.

A randomized trial of yogurt for prevention of antibiotic-associated diarrhea

Antibiotic-associated diarrhea (AAD) is the most common adverse effect of antibiotic therapy. Our aim was to determine the effectiveness of a dietary supplement of yogurt for prevention of AAD. Two hundred two hospitalized patients receiving oral or intravenous antibiotics were randomized to receive or not receive a dietary yogurt supplement, consisting of 227 grams of commercial yogurt, and followed for 8 days. Mean age of the study group was 70 years and 43% were male. Compliance and 8-day follow-up were 85% and 91%, respectively. Patients receiving yogurt reported less frequent diarrhea (12% vs 24%; P = 0.04), and significantly less total diarrhea] days (23 vs 60). The cumulative proportions of patients without diarrhea were significantly different (P = 0.02) between patients receiving and not receiving yogurt. For conclusion, dietary supplementation with yogurt is a simple, effective, and safe treatment that decreases the incidence and duration of AAD.

Klebsiella oxytoca as an agent of antibiotic-associated hemorrhagic colitis

BACKGROUND & AIMS

Klebsiella oxytoca has been isolated from stools and colonic biopsy specimens of patients with Clostridium difficile-negative antibiotic-associated hemorrhagic colitis (AAHC), but the pathogenic role of the germ has not been established. The purpose of this study was to investigate the presence of K. oxytoca in patients with AAHC from a prospective cohort of patients with acute colitis, and to test the cytotoxicity on HEp-2 cells of K. oxytoca strains from patients with AAHC and healthy carriers.

METHODS

Colonic biopsy specimens and a sample of colonic fluid from 93 consecutive patients with acute colitis were cultured on selective media for 7 established pathogens and K. oxytoca. The 2 K. oxytoca strains isolated in the 4 patients with C. difficile-negative AAHC of this cohort and 105 additional K. oxytoca strains from patients with C. difficile-negative AAHC (n = 15) and healthy carriers (n = 90) were tested for cytotoxicity using a HEp-2 cell culture assay.

RESULTS

K. oxytoca was isolated in 50% (2 of 4) of the patients of the prospective cohort with C. difficile-negative AAHC compared with 2% (1 of 41) of the patients with acute colitis caused by established pathogens (P = 0.02). The rate of cytotoxic strains of K. oxytoca was higher in patients with AAHC (82%) than in healthy carriers (42%, P = 0.003).

CONCLUSIONS

We conclude that K. oxytoca is isolated with a significant high rate in patients with C. difficile-negative AAHC, and that K. oxytoca strains from patients with AAHC are cytotoxic more frequently on HEp-2 cells than strains from healthy carriers. These results strengthen the hypothesis of a causative role of K. oxytoca in some of the patients with AAHC.

Incidence and risk factors of oral antibiotic-associated diarrhea in an outpatient pediatric population

BACKGROUND

Little information is available on the epidemiologic characteristics of antibiotic-associated diarrhea (AAD) in children. The authors' aim was to evaluate the incidence of AAD in an outpatient pediatric population and to identify risk factors.

METHODS

Children aged 1 month to 15.4 years treated with oral antibiotics for a proven or suspected infection were enrolled from an ambulatory pediatric practice during an 11-month period. Parents recorded the daily frequency and characteristics of stools using a diary during the antibiotic treatment and for 1 week after it was stopped. An episode of diarrhea was defined by at least 3 soft or liquid stools/d for at least 2 consecutive days. Risk factors for AAD-age, type of antibiotic treatment, type of combined treatment, and site of infection-were analyzed.

RESULTS

Of 650 children included, 11% had an episode of AAD, lasting a mean of 4.0 +/- 3.0 days, beginning a mean of 5.3 +/- 3.5 days after the start of antibiotic treatment. No child was hospitalized because of AAD. The incidence of AAD was higher in children less than 2 years (18%) than in those more than 2 years (3%; P < 0.0001). The incidence of AAD was particularly high after administration of certain antibiotics (amoxicillin/clavulanate, 23%; P = 0.003 compared with other antibiotics). The type of combined treatment and site of infection did not influence the onset of AAD.

CONCLUSIONS

Antibiotic-associated diarrhea was common in these outpatient children, especially for those aged less than 2 years and after the prescription of certain antibiotics, particularly, the combination of amoxicillin/clavulanate.

Recognition of two genetic groups in the Klebsiella oxytoca taxon on the basis of chromosomal beta-lactamase and housekeeping gene sequences as well as ERIC-1 R PCR typing

Whilst searching for a molecular method to identify the different species of Raoultella and Klebsiella oxytoca, it was observed that the OXY-1 and OXY-2 beta-lactamase-producing K. oxytoca isolates displayed two distinguishable enterobacterial repetitive intergenic consensus (ERIC)-1R profiles. It was hypothesized that the two groups of chromosomal beta-lactamases might correspond to two groups of strains in the K. oxytoca taxon. To confirm this hypothesis, clinical isolates and reference strains of K. oxytoca were studied by determination of the sequence of their bla(OXY) genes, and of a partial fragment of their 16S rRNA (387 bp) and rpoB (512 bp) genes. The sequence data were phylogenetically analysed by using the parsimony method. Four clinical isolates possessed a bla(OXY-1) gene and nine possessed a bla(OXY-2) gene. The mean percentage of rpoB and 16S rRNA gene identity was > 99% within each group of strains, whereas it was 96.56 +/- 0.24% for rpoB genes and 97.80 +/- 0.22% for 16S rRNA genes between the group of strains harbouring the bla(OXY-1) gene and the group harbouring the bla(OXY-2) gene. The phylogenetic tree resulting from combined analysis of the 16S rRNA and rpoB datasets showed that the K. oxytoca isolates were monophyletic and separated into two clades; these clades included strains with either the bla(OXY-1) gene or the bla(OXY-2) gene. This result was supported with high bootstrap values of 97 and 99%, respectively. Moreover, the two groups of strains displayed distinct ERIC-1R profiles, with bands characteristic of each profile. Thus, the chromosomal bla(OXY) gene sequence is able to delineate not only two groups of beta-lactamases in K. oxytoca, but also two clades in the K. oxytoca taxon, in a manner similar to the sequence of housekeeping genes. These results suggest that K. oxytoca should be divided into two genetic groups, group OXY-1 represented by K. oxytoca strain SL781 (=CIP 104963) and group OXY-2 by K. oxytoca strain SL91l (= CIP 106098).

Microscopic structure of the large intestinal mucosa in piglets during an antibiotic-associated diarrhea

Antibiotic-associated diarrhea (AAD) is caused by the treatments of broad-spectrum antimicrobials that seriously affect the activity and composition of the large intestinal microflora. The pathogenic bacteria or low concentration of short-chain fatty acids (SCFAs) has been repeatedly discussed in relation to AAD. Recently, we reported the detection of a large amount of succinate and lactate in the diarrheal feces in AAD-induced piglets. In this study, we investigated histologically the large intestinal mucosa in AAD-induced piglets, in which succinate and lactate were accumulated. AAD was induced in the piglets by an oral dose of polymyxin B sulfate (PL) or by an intra-muscular injection of enrofloxacin (ERFX). When the piglets were defecating diarrheal feces with a high concentration of succinate and/or lactate, the large intestine was removed and separated into four segments (cecum, gyri centripetales, gyri centrifugales, and rectum). Healthy piglets were used as the control. In the AAD-induced piglets, the lamina propria was edematous in the gyri centripetales. Piglets treated with ERFX were also edematous in gyri centrifugales. These edematous lamina propria contained larger amounts of inflammatory cells than observed in control tissues. ERFX-treated piglets had a more shallow crypt than PL-treated and control piglets. The mucosal tissue of the large intestine was more seriously damaged in the ERFX- than in the PL-treated piglets, which might have been caused by the high succinate and low SCFAs concentration in the digesta.

Fosmidomycin, a novel chemotherapeutic agent for malaria

In previous studies, fosmidomycin has been shown to possess activity against Plasmodium falciparum in vitro and in the mouse model. It has a novel mode of action through inhibition of 1-deoxy-D-xylulose 5-phosphate reductoisomerase, an enzyme of the nonmevalonate pathway of isoprenoid biosynthesis, which is absent in humans. In this open-label, uncontrolled trial, the efficacy and safety of fosmidomycin, in an oral dose of 1,200 mg every 8 h for 7 days, were evaluated in the treatment of acute uncomplicated Plasmodium falciparum malaria in 20 adult subjects in Gabon and Thailand. Clinical assessments were performed and thick blood smears were evaluated every 8 h until parasite clearance and resolution of symptoms were achieved; assessments continued at weekly intervals thereafter for the duration of the 28-day followup period. All subjects were clinically and parasitologically cured on day 7 (primary end point). Parasite and fever clearance were rapid, with means of 44 and 41 h, respectively. On day 28, seven out of nine subjects (78%) were cured in Gabon and two out of nine subjects (22%) were cured in Thailand. The drug was well tolerated, although mild gastrointestinal side effects were recorded for five subjects. Analysis of hematological and biochemical parameters showed no clinically significant changes throughout the study. Fosmidomycin is an effective and safe antimalarial drug, although its use as a single agent is restricted by the occurrence of recrudescent infections. However, its role in combination therapy should be explored.

Elevated fecal Candida counts in patients with antibiotic-associated diarrhea: role of soluble fecal substances

To assess the role of soluble fecal substances in the elevation of fecal Candida counts in patients with antibiotic-associated diarrhea (AAD), we investigated the growth of Candida albicans in vitro in serially diluted stool fluids from patients with AAD and healthy subjects. There were significantly higher Candida albicans counts in stool fluids diluted 1:10 from AAD patients than in healthy subjects and the phosphate-buffered saline growth control, which may be due to reduced soluble Candida inhibitors and increased availability of growth factors and nutrients.

[Antibiotic induced diarrhea and pseudomembranous colitis]

The spore-forming anaerobic bacterium Clostridium difficile has become a serious enteropathogen. Oral and parenteral administration of antibiotics can cause ecological disturbances in the normal intestinal microflora. Suppression of the normal microflora may lead to reduced colonization resistance with subsequent overgrowth by pre-existing, naturally resistant microorganisms, such as C. difficile. C. difficile infection shows a range of clinical presentations between an asymptomatic carrier state, light diarrhea without inflammatory changes, and pseudomembranous colitis. C. difficile infection is acquired by the fecal-oral or environmental-oral routes. From March 2000 through March 2001 we assessed 48 cases of nosocomial antibiotic-associated diarrhea (AAD). Of these, 21 were due to C. difficile (CDAD). Cephalosporin was the agent most commonly associated with CDAD. Avoidance of cephalosporins, strict use of "single shot" prophylaxis, isolation of infected, symptomatic patients in single-bed rooms, improved hygiene and complete room disinfection lead to a rapid decrease of CDAD. The etiology, prognosis and prophylaxis are discussed in this paper.

Synthetic analogues of beta-1,2 oligomannosides prevent intestinal colonization by the pathogenic yeast Candida albicans

The pathogenic yeast Candida albicans displays at its cell surface beta-1,2 oligomannosides (beta-1,2-Mans). In contrast to the ubiquitous alpha-Mans, beta-1,2-Mans bind to galectin-3, a major endogenous lectin expressed on epithelial cells. The specific role of beta-1,2-Mans in colonization of the gut by C. albicans was assessed in a mouse model. A selected virulent strain of C. albicans (expressing more beta-1,2-Man epitopes) induced more intense and sustained colonization than an avirulent strain (expressing less beta-1,2-Man epitopes). Synthetic (Sigma) beta-and alpha-linked tetramannosides with antigenicities that mimicked the antigenicities of C. albicans-derived oligomannosides were then constructed. Oral administration of Sigmabeta-1,2-Man (30 mg/kg of body weight) prior to inoculation with the virulent strain resulted in almost complete eradication of yeasts from stool samples, whereas administration of Sigmaalpha-Man at the same dose did not. As most cases of human systemic candidiasis are endogenous in origin, this first demonstration that a synthetic analogue of a yeast adhesin can prevent yeast colonization in the gut opens the possibility of new prophylactic strategies.

Probiotics in antibiotic-associated diarrhoea

Antibiotic-associated diarrhoea is a common event. In some cases, it could represent a life-threatening event. Clostridium difficile colitis is a further distinct complication of antibiotic administration. Treatment options for antibiotic-associated diarrhoea and Clostridium difficile colitis include supplementation with several types of probiotics, as overviewed in this paper. Three randomised, double-blind, controlled clinical trials show a therapeutic effect of Saccharomyces boulardii in antibiotic-associated diarrhoea. The efficacy of Lactobacillus acidophilus and bulgaricus has also been ascertained in two double-blind controlled studies. Other studies focusing on Lactobacillus as a new preventive agent for antibiotic-associated diarrhoea are not double-blind. Among these, a positive effect of Lactobacillus rhamnosus GG, Bifidobacterium longum and Enterococcus faecium SF68 has been reported. Effectiveness of probiotics in antibiotic-associated diarrhoea has, therefore, a consistent scientific rationale, however few studies have performed an assessment of bacterial recovery in stools, and this approach may be helpful in deciding a more rigorous dose standardisation.

Biotherapeutics and biotherapy of surgical enteropathies

Probiotic agents are living micro-organisms that, upon ingestion, exert health benefits beyond inherent general nutrition. In this context, we must differentiate between biotherapeutics as approved drugs and dietary supplements and food products containing prebiotic bacteria that are not considered drugs. At present, the only biotherapeutic agent which is prescribable in some European countries, indicated to relieve specific diseases, is the yeast Saccharomyces boulardii. In this review, we consider the various pre-clinical and clinical aspects of biotherapeutics as basic drugs and the biotherapeutic powers of their use in the treatment of some surgical enteropathies.

Succinate accumulation in pig large intestine during antibiotic-associated diarrhea and the constitution of succinate-producing flora

Succinate was the major organic acid detected in the hindgut content of pigs suffering from antibiotic-associated diarrhea. Antibiotic-associated diarrhea was induced by an oral dose of polymyxin B sulfate (3,000,000 units/day) or an intramuscular injection of enrofloxacin (0.6 g enrofloxacin/day). In the large intestine of enrofloxacin-treated pigs, Gram-negative facultative anaerobic rods phylogenetically related to Escherichia coli and Gram-positive facultative anaerobic non-spore-forming rods phylogenetically related to Lactobacilli were isolated as succinate producers. Succinate-producing Lactobacilli were only isolated as the succinate producer in polymyxin B sulfate-treated pigs. In contrast to antibiotic-associated diarrhea pigs, bacteria belonging to Bacteroidaceae, Fusobacteria, and Enterobacteriaceae were detected as succinate producers in a non-treated pig. In antibiotic-associated diarrhea conditions, antibiotic-resistant Enterobacteria, E. coli in particular, and Lactobacilli may contribute to an abnormal succinate accumulation and may affect water absorption in the hindgut that relates to an expression of antibiotic-associated diarrhea.

The pathogenetic significance of intestinal Candida colonization--a systematic review from an interdisciplinary and environmental medical point of view

The etiological significance of intestinal Candida colonization continues to be controversial. This is a systematic review to determine the pathogenetic significance of intestinal Candida colonization. The search was essentially performed from 1990 to 12/7/2000 in Medline and the Cochrane-Library. The data source was restricted to articles in English and German. Selection criteria covered the topics "Epidemiology", "Infectious Diseases", "Candida-Syndrome" and "Therapy" and were essentially confined to in-vivo examination of immunocompetent adults. Two reviewers extracted independently data using predefined criteria. In total, 96 citations that proved suitable for use in the systematic review were found. Depending on the localization in the gastrointestinal tract, the recovery technique employed, and transport times, Candida colonization is frequently detected in healthy, immunocompetent adults (prevalence: 4-88%). None of the studies available so far furnish any evidence that nutritional factors, food additives, pollutants, anti-ovulants, other types of medication or diabetes mellitus might be predisposing factors for intestinal Candida colonization. However, therapeutic studies point to the possibility of Candida playing a role in antibiotic-associated diarrhea. On the other hand, antibiotics seem to favor bacterial dysbiosis, and this, like the direct side effects of drugs, offers a more plausible explanation for diarrhea or gastrointestinal symptoms. The role of intestinal colonization by Candida in Candida-associated vulvovaginitis and IgE-mediated disorders remains contradictory. Nevertheless, neither epidemiological nor therapeutic studies provide evidence for the existence of the so-called "Candida-syndrome" or "Candida-hypersensitivity-syndrome". At present, there are no proven treatment indications for antifungal "bowel decontamination".

Organic acid profiles in feces of pigs with pathogenic or non-pathogenic diarrhea

A chemical characteristic of the feces of diarrheal piglets permits differentiation among piglets receiving antibiotic treatment and those with colibacillosis or dyspepsia. A high concentration of lactic or succinic acid was observed in the diarrheic feces of piglets receiving antibiotic treatments and those with dyspepsia; however, no lactic or succinic acids were detected in piglets with colibacillosis. There was, however, little difference in the total concentration of organic acids among the three types of diarrheal illnesses. A quantitative analysis of lactic and succinic acids in diarrheic feces might provide a means for rapidly differentiating between colibacillosis and non-pathogenic diarrheas in piglets.

Preclinical and clinical pharmacology of biotherapeutic agents: Saccharomyces boulardii

Probiotic agents are living microorganisms that, upon ingestion, exert health benefits beyond inherent general nutrition. In this context, we must differentiate between biotherapeutics as approved drugs and dietary supplements and food products containing probiotic bacteria that are not considered drugs. At present the only biotherapeutic agent which is prescribable in some European countries, indicated to relieve specific diseases, is the yeast Saccharomyces boulardii. In this review we consider the various preclinical and clinical aspects of biotherapeutics as basic drugs and the biotherapeutic powers of their use in the treatment of some surgical enteropathies.

The role of antibiotics in the treatment of infectious diarrhea

Infectious diarrhea is a significant cause of morbidity and mortality and a common complaint in clinical practice. Routine empirical use of antibiotics for infectious diarrhea should be avoided because of the self-limited nature of most cases, the cost of antibiotics, and the potential to worsen the already significant problem of antibiotic resistance of enteric pathogens. For patients with severe invasive or prolonged diarrhea or who are at high risk of complications, such as the elderly, diabetics, cirrhotics, and immunocompromised patients, empirical treatment with a quinolone antibiotic for 3 to 5 days can be considered. Antibiotic treatment can be highly effective for Shigella, ETEC, and V. cholerae infections, and metronidazole is indicated for C. difficile colitis. The impact of antibiotics for other specific pathogens is modest, and antibiotic therapy should be reserved for the same group of patients who would be considered for empirical treatment. The most significant problem in the antibiotic treatment of infectious diarrhea is the progressive increase in resistance among enteric pathogens; only the prudent use of antimicrobials in all areas of daily practice can limit or delay the impact of this serious problem.

A prospective study of the roles of clostridium difficile and enterotoxigenic Clostridium perfringens in equine diarrhoea

Faecal samples from adult horses and from foals with diarrhoea or with normal faeces were evaluated for the presence of Clostridium difficile, C. difficile toxins, C. perfringens enterotoxin (CPE) and C. perfringens spore counts. Clostridium difficile was isolated from 7/55 horses (12.7%) and 11/31 foals (35.5%) with colitis, but from 1/255 normal adults (0.4%) and 0/47 normal foals (P<0.001). Clostridium difficile toxins A and/or B were detected in 12/55 diarrhoeic adults (21.8%) and 5/30 diarrhoeic foals (16.7%) but in only 1/83 adults (1.2%) and 0/21 foals with normal faeces (P<0.001 and P<0.05, respectively). Clostridium perfringens enterotoxin was detected in 9/47 diarrhoeic adults (19%) and 8/28 diarrhoeic foals (28.6%), but was not detected in 47 adult horses (P<0.002) or 4 foals (P = 0.22) with normal faeces. The positive predictive value of isolation of C. perfringens with respect to the presence of CPE was only 60% in adult horses and 64% in foals. There was no association between total C. perfringens spore count and CPE in the faeces. The overall mortality rate from colitis was 22% for adult horses and 18% for foals. Clostridium difficile toxin-positive adult horses with colitis were less likely to survive than C. difficile-negative horses with colitis (P = 0.03). This study provides further evidence that C. difficile and enterotoxigenic C. perfringens are associated with equine enterocolitis.

Suspected Clostridium difficile-associated diarrhea in two cats

Two adult cats from the same household developed acute diarrhea. Clostridium difficile toxins were detected in the feces of both cats, whereas other recognized causes of diarrhea were not identified. Supportive medical treatment and metronidazole were administered and both cats responded well. A fecal sample obtained from 1 of the affected cats after treatment and a fecal sample obtained from a clinically normal cat in the household did not contain C difficile toxins. The role of C difficile in enteric disease in cats has not been extensively studied and is unclear; however, our findings suggest that toxigenic strains of C difficile may cause diarrhea in cats.

Management and Prevention of Clostridium difficile-Associated Diarrhea

Clostridium difficile is a major cause of antibiotic-associated diarrhea. While treatment regimens for C. difficile have been available for decades, they remain less than optimal due to the frequent recurrences that occur after therapy is completed. Moreover, the morbidity and expense associated with C. difficile have underscored the need for more effective preventive measures than are currently available. In this review, we outline the current recommendations for treatment and prevention of C. difficile infection and, highlight some promising new approaches that may help to control this common nosocomial pathogen in the future.

Evaluation of six commercial assays for the rapid detection of Clostridium difficile toxin and/or antigen in stool specimens

OBJECTIVE

To evaluate six commercially available assays for the detection of Clostridium difficile toxin and/or antigen in stool samples: one latex agglutination test (Culturette brand CDT, Becton Dickinson), two ELISAs (Culturette brand Toxin CD, Becton Dickinson, and Ridascreen C. difficile Toxin A/B, R-biopharm), two chromatographic assays (Clearview C. difficile A, Oxoid, and ColorPac Toxin A, Becton Dickinson) and one enzyme immunoassay for the simultaneous detection of C. difficile common antigen and toxin A (Triage C. difficile Panel, Biosite).

METHODS

Over a period of 3 months, 366 liquid or semi-liquid stool samples were tested using cell-culture cytotoxin assay as standard, ethanol shock stool culture and latex agglutination (Culturette brand CDT). Of these, 78 samples, positive with at least one of these three methods, and 98 randomly selected negative samples were further evaluated using the other five kits. PCR was also performed on positive cultures to confirm the presence of toxin A and B genes.

RESULTS

Triage C. difficile Panel had the best sensitivity (95%), followed by Clearview C. difficile and ColorPac Toxin A (both 89%), Culturette brand Toxin CD (73%), Ridascreen C. difficile Toxin A/B (57%) and Culturette brand CDT (23%). For Triage, the sensitivity of C. difficile antigen detection was 93%, and the sensitivity of toxin detection was lower (77%). Most false-positive results were obtained with the Triage C. difficile Panel (25 specimens) and Clearview C. difficile A (20 specimens). Culturette brand CDT had the best specificity (99%); followed by Ridascreen C. difficile Toxin A/B (97%), Culturette brand Toxin CD (95%), ColorPac Toxin A (89%), Clearview C. difficile A (83%) and Triage C. difficile Panel (75%). The positive predictive values ranged from 68% to 94%, and the negative predictive values from 83% to 98%.

CONCLUSIONS

The sensitivity is much higher for Triage and the two new chromatographic assays than for the conventional EIAs. These tests also have a high negative predictive value. For Triage, C. difficile antigen-positive, toxin A-negative results can be obtained; the clinical value of these must be established by additional studies. Overall, the new-generation assays are still less sensitive than the cytotoxin assay; however, they provided same-day results, could be used as a screening test and may be useful in laboratories without tissue-culture facilities. Our results do not allow the recommendation of one single assay for the diagnosis of C. difficile-associated diarrhea. It remains the case that laboratory results must be correlated and interpreted with the clinical presentation of the patient.

Treatment and prevention of antibiotic associated diarrhea

Mild or severe episodes of antibiotic-associated diarrhea (AAD) are common side effects of antibiotic therapy. The incidence of AAD differs with the antibiotic and varies from 5 to 25%. The major form of intestinal disorders is the pseudomembranous colitis associated with Clostridium difficile which occurs in 10-20% of all AAD. In most cases of AAD discontinuation or replacement of the inciting antibiotic by another drug with lower AAD risk can be effective. For more severe cases involving C. difficile, the treatment of diarrhea requires an antibiotic treatment, with glycopeptides (vancomycin) or metronidazole. Another approach to AAD treatment or prevention is based on the use of non-pathogenic living organisms, capable of re-establishing the equilibrium of the intestinal ecosystem. Several organisms have been used in treatment or prophylaxis of AAD such as selected strains of Lactobacillus acidophilus, L. bulgaricus, Bifidobacterium longum, and Enterococcus faecium. Another biotherapeutic agent, a non-pathogenic yeast, Saccharomyces boulardii has been used. In animal models of C. difficile colitis initiated by clindamycin, animals treated with S. boulardii (at end of vancomycin therapy) had a significant decrease in C. difficile colony-forming units, and of toxin B production. In several clinical randomised trials (versus placebo), S. boulardii has demonstrated its effectiveness by decreasing significantly the occurrence of C. difficile colitis and preventing the pathogenic effects of toxins A and B of C. difficile. It has been shown to be a safe and effective therapy in relapses of C. difficile colitis. A good response has been seen in children with AAD, treated by S. boulardii only. In ICUs prevention of AAD remains based on limitation of antibiotic overuse and spread of C. difficile or other agents of AAD should be prevented by improved hygiene measures (single rooms, private bathrooms for patients, use of gloves and hand washing for personnel). In addition the increasing use of biotherapeutic agents such as S. boulardii should permit the prevention of the major side effect of antibiotics, i.e. AAD in at risk patients.

The value of ultrasonography for hepatic surgery

Ultrasonography plays an important role in the early detection of hepatocellular carcinoma. Ultrasonography detected 53% of 287 patients with small (less than or equal to 5 cm) hepatocellular carcinomas. Among 486 patients with hepatocellular carcinomas, sensitivities of intra-operative ultrasonography in detecting 451 small primary hepatocellular carcinoma nodules, intrahepatic metastasis in 330 patients with small hepatocellular carcinoma and 63 tumor thrombi were 98, 48 and 67%, respectively. The sensitivity of intra-operative ultrasonography in detecting small primary tumors was 10% better than ultrasonography, computed tomography, and angiography. The sensitivity of intra-operative ultrasonography in intrahepatic metastasis and tumor thrombus was two to three times better than pre-operative examination. Intra-operative ultrasonography was useful in detecting nonpalpable tumors and in guiding the transection of the liver, biopsy, and cryosurgery. Moreover, intra-operative ultrasonography made possible new hepatectomy procedures: systematic subsegmentectomy and hepatectomies which preserve the inferior right hepatic vein. Systematic subsegmentectomy guided by intra-operative ultrasonography resulted in better survival rates than the limited resection in patients with small hepatocellular carcinoma two years after hepatectomy; by the sixth year, this difference was significant (p less than 0.05). Ultrasonography and intra-operative ultrasonography are indispensable in the early detection, accurate diagnosis, operative guidance and postoperative care of hepatocellular carcinoma.