Mechanisms and management of antibiotic-associated diarrhea

Infection Probability Score: a predictor of Clostridium difficile-associated disease onset in patients with haematological malignancy

PURPOSE

to assess the predictive power of three systems: Infection Probability Score, APACHE II and KARNOFSKY score for the onset of Clostridium difficile-associated disease (CDAD) in hematology-oncology patients.

METHODS AND SAMPLE

A retrospective pilot surveillance survey was conducted in the hematology unit of a general hospital in Greece. Data were collected by using an anonymous standardised case-record form. The sample consisted of 102 hospitalized patients.

RESULTS

The majority of the patients (33.3%) suffered from acute myeloid leukemia. The cumulative incidence of CDAD was 10.8% and the incidence rate of C difficile associated diarrhea was 5 per 1000 patient-days (14.2 per 1000 patient-days at risk). Patients with CDAD had twofold higher time of mean length of hospital stay compared with patients without CDAD (38.82 ± 23.88 vs 19.45 ± 14.56 days). Additionally patients with CDAD had received a greater number of different antibiotics compared to those without CDAD (5.18 ± 1.99 vs 2.54 ± 2.13), suffered from diabetes, from non Hodgkin's lymphoma, had a statistically significant higher duration of neutropenia ≥3 days and had received antifungal treatment. The best cutoff value of IPS for the prediction of CDAD was 13 with a sensitivity of 45.5% and a specificity of 82.4%.

CONCLUSIONS

IPS is an early diagnostic test for CDAD detection.

Construction and characterization of a lactose-inducible promoter system for controlled gene expression in Clostridium perfringens

Clostridium perfringens is a Gram-positive anaerobic pathogen which causes many diseases in humans and animals. While some genetic tools exist for working with C. perfringens, a tightly regulated, inducible promoter system is currently lacking. Therefore, we constructed a plasmid-based promoter system that provided regulated expression when lactose was added. This plasmid (pKRAH1) is an Escherichia coli-C. perfringens shuttle vector containing the gene encoding a transcriptional regulator, BgaR, and a divergent promoter upstream of gene bgaL (bgaR-P(bgaL)). To measure transcription at the bgaL promoter in pKRAH1, the E. coli reporter gene gusA, encoding β-glucuronidase, was placed downstream of the P(bgaL) promoter to make plasmid pAH2. When transformed into three strains of C. perfringens, pAH2 exhibited lactose-inducible expression. C. perfringens strain 13, a commonly studied strain, has endogenous β-glucuronidase activity. We mutated gene bglR, encoding a putative β-glucuronidase, and observed an 89% decrease in endogenous activity with no lactose. This combination of a system for regulated gene expression and a mutant of strain 13 with low β-glucuronidase activity are useful tools for studying gene regulation and protein expression in an important pathogenic bacterium. We used this system to express the yfp-pilB gene, comprised of a yellow fluorescent protein (YFP)-encoding gene fused to an assembly ATPase gene involved in type IV pilus-dependent gliding motility in C. perfringens. Expression in the wild-type strain showed that YFP-PilB localized mostly to the poles of cells, but in a pilC mutant it localized throughout the cell, demonstrating that the membrane protein PilC is required for polar localization of PilB.

First report of septic arthritis caused by Klebsiella oxytoca

Klebsiella oxytoca is known to be a pathogen in immunodeficient adults and children. Here we report the first case of a K. oxytoca infection associated with spontaneous arthritis of the knee in a child with no history of immunosuppressive therapy or previous bacterial infections. Despite an initial antibiotic treatment failure, a second treatment led to a cure of the infection with no joint sequelae.

Burden of acute gastrointestinal illness in the Metropolitan region, Chile, 2008

The purpose of this study was to determine the magnitude and distribution of acute gastrointestinal illness (GI) in the Chilean population, describe its burden and presentation, identify risk factors associated with GI and assess the differences between a 7-day, 15-day and a 30-day recall period in the population-based burden of illness study design. Face-to-face surveys were conducted on 6047 randomly selected residents in the Metropolitan region, Chile (average response rate 75·8%) in 2008. The age-adjusted monthly prevalence of GI was 9·2%. The 7-day recall period provided annual incidence rate estimates about 2·2 times those of the 30-day recall period. Age, occupation, healthcare system, sewer system, antibiotic use and cat ownership were all found to be significant predictors for being a case. This study expands on the discussion of recall bias in retrospective population studies and reports the first population-based burden and distribution of GI estimates in Chile.

Role of colonic short-chain fatty acid transport in diarrhea

Short-chain fatty acids (SCFA) are the major anion in stool and are synthesized from nonabsorbed carbohydrate by the colonic microbiota. Nonabsorbed carbohydrate are not absorbed in the colon and induce an osmotically mediated diarrhea; in contrast, SCFA are absorbed by colonic epithelial cells and stimulate Na-dependent fluid absorption via a cyclic AMP-independent process involving apical membrane Na-H, SCFA-HCO(3), and Cl-SCFA exchanges. SCFA production represents an adaptive process to conserve calories, fluid, and electrolytes. Inhibition of SCFA synthesis by antibiotics and administration of PEG, a substance that is not metabolized by colonic microbiota, both result in diarrhea. In contrast, increased production of SCFA as a result of providing starch that is relatively resistant to amylase digestion [so-called resistant starch (RS)] to oral rehydration solution (RS-ORS) improves the efficacy of ORS and represents an important approach to improve the effectiveness of ORS in the treatment of acute diarrhea in children under five years of age.

Role of Lactobacillus in the prevention of antibiotic-associated diarrhea: a meta-analysis

STUDY OBJECTIVE

To evaluate the efficacy of a Lactobacillus probiotic single-agent regimen in preventing antibiotic-associated diarrhea (AAD).

DESIGN

Meta-analysis of 10 randomized, blinded, placebo-controlled trials. Patients. A total of 1862 pediatric and adult patients who received a Lactobacillus single-agent regimen or placebo for the prevention of AAD.

MEASUREMENTS AND MAIN RESULTS

The MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials databases were searched from inception through May 2008 by two investigators independently using the following key words: probiotic, Lactobacillus, antibiotic-associated diarrhea. Full reports published in English were included if the studies were randomized, blinded, and placebo-controlled trials that evaluated the efficacy of Lactobacillus single-agent regimens versus placebo in the prevention of AAD. Bibliographies of recent review articles and systematic reviews were hand searched. Quality of the studies was assessed by using the Jadad scoring system. Number of subjects, age, Lactobacillus regimen, follow-up period, and occurrence of AAD were extracted into a standardized data collection form. Overall impact of Lactobacillus on AAD was compared with placebo by using a random-effects model. Ten studies with a total of 1862 patients (50.4% male) met all criteria. Six studies included patients aged 18 years or older, whereas four included patients younger than 18 years (range 2 wks-14 yrs). Jadad scores ranged from 2-5 (out of 5). The total daily dose of Lactobacillus ranged from 2 x 10(9)-4 x 10(10) colony-forming units and was administered throughout the entire antibiotic treatment (5-14 days) for all patients. The follow-up period varied from 2 days-3 months after the end of the probiotic regimen. The combined risk ratio (RR) of developing AAD was significantly lower with Lactobacillus compared with placebo (RR 0.35, 95% confidence interval [CI] 0.19-0.67). In a subgroup analysis, this held true for adults but not pediatric patients (RR 0.24, 95% CI 0.08-0.75 and RR 0.44, 95% CI 0.18-1.08, respectively).

CONCLUSION

Administration of a Lactobacillus single-agent regimen as a prophylactic agent during antibiotic treatment reduced the risk of developing AAD compared with placebo in adults but not pediatric patients.

Efficacy of BIO K+ CL1285 in the reduction of antibiotic-associated diarrhea - a placebo controlled double-blind randomized, multi-center study

INTRODUCTION

Antibiotic associated diarrhea (AAD) is a frequently encountered adverse event following antibiotic administration. Evidence suggests that probiotics may be beneficial in preventing and decreasing the severity of AAD.

MATERIAL AND METHODS

Adult patients who were prescribed antibiotics for 3-14 days were enrolled from eight Canadian centers. Study treatment was randomized at a 1 : 1 ratio of BIO-K+CL1285( (®) ) or placebo and was administered within 24 h of initiation to 5 days after termination of antibiotherapy. Patients were followed for 21 days after last dose of study treatment. The primary outcome was severity and incidence of AAD. Severity was measured by the total number of days with diarrhea and incidence was defined as the number of patients with at least one day with diarrhea over the total number of patients enrolled in the study.

RESULTS

216 patients were randomized to BIO-K+ and 221 to placebo. The mean (SD) number of days with diarrhea was 1.19. (3.20) days for the placebo and 0.67 (2.05) days for BIO-K+CL1285( (®) ) (p = 0.040). Adjusted multivariate linear regression results showed that the duration of diarrhea for BIO-K+CL1285 (®)vs. placebo was reduced by 51.5% (b[SE] = 0.515 [0.256], p = 0.045). The incidence of diarrhea was 21.8% for the BIO-K+ and 29.4% for the placebo group (OR = 0.667, p = 0.067). Multivariate logistic regression, showed that the adjusted odds ratio of AAD in patients receiving BIO-K+ vs. placebo was 0.627 (p = 0.037). Study treatment was well tolerated.

CONCLUSIONS

BIO-K+ is effective for preventing and reducing the severity of AAD in patients receiving antibiotic therapy in a hospital setting.

Intake of Lactobacillus plantarum reduces certain gastrointestinal symptoms during treatment with antibiotics

GOALS

To examine if intake of Lactobacillus plantarum can prevent gastrointestinal side effects in antibiotic-treated patients.

BACKGROUND

Diarrhea is a common side effect of treatment with antibiotics. Some studies indicate that the risk of antibiotic-associated diarrhea can be reduced by administration of certain probiotic microorganisms.

STUDY

Patients treated for infections at a university hospital infectious diseases clinic were randomized to daily intake of either a fruit drink with L. plantarum 299v (10(10) colony forming units/d) or a placebo drink, until a week after termination of antibiotic treatment. Subjects recorded the number and consistency of stools as well as gastrointestinal symptoms until up to 3 weeks after last intake of test drink. Fecal samples were collected before the first intake of test drink and after termination of antibiotic therapy and analyzed for Clostridium difficile toxin.

RESULTS

Clinical characteristics on admission were similar in the 2 groups. The overall risk of developing loose or watery stools was significantly lower among those receiving L. plantarum [odds ratio (OR), 0.69; 95% confidence interval (CI), 0.52-0.92; P=0.012], as was development of nausea (OR, 0.51; 95% CI, 0.30-0.85; P=0.0097). Diarrhea defined as > or =3 loose stools/24 h for > or =2 consecutive days was unaffected by the treatment (OR, 1.4; 95% CI, 0.33-6.0; P=0.86). No significant differences regarding carriage of toxin producing C. difficile were observed between the groups.

CONCLUSIONS

Our results indicate that intake of L. plantarum could have a preventive effect on milder gastrointestinal symptoms during treatment with antibiotics.

The effect of a multispecies probiotic on the composition of the faecal microbiota and bowel habits in chronic obstructive pulmonary disease patients treated with antibiotics

Short-term antibiotic treatment profoundly affects the intestinal microbiota, which may lead to sustained changes in microbiota composition. Probiotics may restore such a disturbance. The objective of the present study was to investigate the effect of a multispecies probiotic on the faecal microbiota during and after antibiotic intake in patients with a history of frequent antibiotic use. In this randomised, placebo-controlled, double-blind study, thirty chronic obstructive pulmonary disease (COPD) patients treated with antibiotics for a respiratory tract infection received 5 g of a multispecies probiotic or placebo twice daily for 2 weeks. Faecal samples were collected at 0, 7, 14 and 63 d. Changes in the composition of the dominant faecal microbiota were determined by PCR-denaturing gradient gel electrophoresis (DGGE). Changes in bacterial subgroups were determined by quantitative PCR and culture. Bowel movements were scored daily according to the Bristol stool form scale. During and after antibiotic treatment, DGGE-based similarity indices (SI) were high ( ≥ 84 %) and band richness was relatively low, both remaining stable over time. No difference in SI was observed between patients with and without diarrhoea-like bowel movements. The multispecies probiotic had a modest effect on the bacterial subgroups. Nevertheless, it affected neither the composition of the dominant faecal microbiota nor the occurrence of diarrhoea-like bowel movements. The dominant faecal microbiota was not affected by antibiotics in this COPD population, suggesting an existing imbalance of the microbiota, which may also have contributed to the lack of effect by probiotic intake.

Nosocomial and antibiotic-associated diarrhoea caused by organisms other than Clostridium difficile

Most cases of nosocomial and antibiotic-associated diarrhoea are caused by alteration of the physiological gut microflora. This alteration leads to reduced microbial metabolism of carbohydrates and primary bile acids, resulting in osmotic or secretory forms of diarrhoea. Moreover, facultative enteropathogens may experience a growth advantage due to the antibiotic-induced microflora alteration that, in turn, can harm the gut mucosa by the toxins they produce. Clostridium difficile is the major infectious agent leading to pseudomembranous colitis. However, there is increasing evidence that certain other pathogens such as enterotoxin-producing Clostridium perfringens, Staphylococcus aureus and Klebsiella oxytoca can induce mucosal deterioration and diarrhoea after antibiotic use. But, as with C. difficile, these facultative enteropathogens can also be found in the healthy population. Their contribution to disease is, therefore, controversial and their presence in the stools of antibiotic-associated diarrhoea patients is often claimed to be mere colonisation. In this respect, the causal relationship of each suspected pathogen with the development of intestinal disease has to be proved clinically and experimentally.

Clinical outcomes, safety, and pharmacokinetics of OPT-80 in a phase 2 trial with patients with Clostridium difficile infection

OPT-80, a novel, minimally absorbed macrocycle, is a candidate treatment option for Clostridium difficile infection (CDI) based on cure without recurrence of CDI in the hamster challenge model, good in vitro activity against C. difficile, and relative sparing of commensal gram-negative anaerobes. In this open-label, dose-ranging clinical trial, 48 evaluable subjects were randomized to receive either 50, 100, or 200 mg of OPT-80 orally every 12 h for 10 days as treatment for mild to moderately severe CDI. OPT-80 was well tolerated by all subjects. Plasma concentrations were below the lower limit of quantitation in almost one-half of patients and typically <or=20 ng/ml across the dose range; the mean fecal concentrations exceeded the MIC at which 90% of the isolates tested are inhibited by 2,000- to 10,000-fold with increasing dosages. Resolution of diarrhea within 10 days was achieved in 10/14 patients (71%), 12/15 patients (80%), and 15/16 patients (94%), and the median time to resolution of diarrhea was reduced from 5.5 to 3.0 days with increasing dosages. Across all groups, the clinical cure rate, which was defined as resolution of diarrheal disease without the need for further treatment, was 41/45 patients (91%). Recurrence of CDI at approximately 1 month after treatment was observed in two (5%) patients, one each in the 100-mg and 400-mg groups. The apparent high clinical response, good tolerance, low recurrence rate, and more-complete and rapid symptom control with the highest dosage support the selection of the 200-mg twice-daily dose for further clinical development of OPT-80 for treatment of CDI.

The role of colonic metabolism in lactose intolerance

Lactose maldigestion and intolerance affect a large part of the world population. The underlying factors of lactose intolerance are not fully understood. In this review, the role of colonic metabolism is discussed, i.e. fermentation of lactose by the colonic microbiota, colonic processing of the fermentation metabolites and how these processes would play a role in the pathophysiology of lactose intolerance. We suggest that the balance between the removal and production rate of osmotic-active components (lactose, and intermediate metabolites, e.g. lactate, succinate, etc.) in the colon is a key factor in the development of symptoms. The involvement of the colon may provide the basis for designing new targeted strategies for dietary and clinical management of lactose intolerance.

Tolevamer, an anionic polymer, neutralizes toxins produced by the BI/027 strains of Clostridium difficile

Clostridium difficile-associated diarrhea (CDAD) is caused by the toxins the organism produces when it overgrows in the colon as a consequence of antibiotic depletion of normal flora. Conventional antibiotic treatment of CDAD increases the likelihood of recurrent disease by again suppressing normal bacterial flora. Tolevamer, a novel toxin-binding polymer, was developed to ameliorate the disease without adversely affecting normal flora. In the current study, tolevamer was tested for its ability to neutralize clostridial toxins produced by the epidemic BI/027 strains, thereby preventing toxin-mediated tissue culture cell rounding. The titers of toxin-containing C. difficile culture supernatants were determined using confluent cell monolayers, and then the supernatants were used in assays containing dilutions of tolevamer to determine the lowest concentration of tolevamer that prevented > or =90% cytotoxicity. Tolevamer neutralized toxins in the supernatants of all C. difficile strains tested. Specific antibodies against the large clostridial toxins TcdA and TcdB also neutralized the cytopathic effect, suggesting that tolevamer is specifically neutralizing these toxins and that the binary toxin (whose genes are carried by the BI/027 strains) is not a significant source of cytopathology against tissue culture cells in vitro.

A new formulation of tolevamer, a novel nonantibiotic polymer, is safe and well-tolerated in healthy volunteers: a randomized phase I trial

AIMS

To evaluate the safety and tolerability of a new oral solution formulation of tolevamer potassium sodium, a nonantibiotic polymer that binds Clostridium difficile toxins A and B.

METHODS

This phase 1 randomized, double-blind, placebo-controlled study evaluated four doses of tolevamer potassium sodium in 40 healthy volunteers using a sequential dose escalation paradigm and doses of 6, 9, 12 and 15 g day(-1) for 9 days. Within each 10 patient cohort, eight patients received active treatment and two matching placebo. Placebo subjects were pooled to provide eight per arm. All subjects received three times daily dosing on days 2-8 as well as a loading dose (a single dose equal to the total daily dose) either on day 1 or day 9.

RESULTS

All 40 subjects completed the study per protocol. Treatment-emergent adverse events (TEAEs) were generally mild, transient, and resolved without sequelae. There were no serious AEs or deaths. There was no relationship detected between dose and the incidence of TEAEs, whether drug-related (all gastrointestinal disorders) or not. No clinically significant changes in laboratory parameters, including serum and urinary potassium concentrations, vital signs, and results of physical examination, were observed. A small but statistically significant reduction in 24 h urine potassium excretion was seen in the 15 g day(-1) dose group, and on day 10 in the 6 g day(-1) group.

CONCLUSIONS

Tolevamer oral solution administered for 9 days at total daily doses up to 15 g, with loading doses of up to 15 g, was generally safe and well-tolerated in healthy volunteers.

Antibiotic-associated diarrhea: candidate organisms other than Clostridium difficile

BACKGROUND/AIMS

The direct toxic effects of antibiotics on the intestine can alter digestive functions and cause pathogenic bacterial overgrowth leading to antibiotic-associated diarrhea (AAD). Clostridium difficile (C. difficile) is widely known to be responsible for 10 approximately 20% of AAD cases. However, Klebsiella oxytoca, Clostridium perfringens, Staphylococcus aureus, and Candida species might also contribute to AAD.

METHODS

We prospectively analyzed the organisms in stool and colon tissue cultures with a C. difficile toxin A assay in patients with AAD between May and December 2005. In addition, we performed the C. difficile toxin A assays using an enzyme-linked fluorescent assay technique. Patients were enrolled who had diarrhea with more than three stools per day for at least 2 days after the initiation of antibiotic treatment for up to 6 approximately 8 weeks after antibiotic discontinuation.

RESULTS

Among 38 patients (mean age 59 +/- 18 years, M:F =18:20), the organism isolation rates were 28.9% (11/38) for stool culture, 18.4% (7/38) for colon tissue cultures and 13.2% (5/38) for the C. difficile toxin A assay. The overall rate of identification of organisms was 50.0% (19/38). Of the five patients that had a positive result by the C. difficile toxin A assay, two had no organism isolated by the stool or colon tissue culture. The organisms isolated from the stool cultures were C difficile (4), Klebsiella pneumoniae (K. pneumoniae) (3), Candida species (3), and Staphylococcus aureus (1). C. difficile (4) and K. pneumoniae (3) were isolated from the colon tissue culture.

CONCLUSIONS

For C. difficile negative AAD patients, K. pneumoniae, Candida species and Staphylococcus aureus were found to be potential causative organisms.

The effect of a multispecies probiotic on the intestinal microbiota and bowel movements in healthy volunteers taking the antibiotic amoxycillin

BACKGROUND

One of the side effects of antimicrobial therapy is a disturbance of the intestinal microbiota potentially resulting in antibiotic-associated diarrhea (AAD). In this placebo-controlled double-blind study, the effect of a multispecies probiotic on the composition and metabolic activity of the intestinal microbiota and bowel habits was studied in healthy volunteers taking amoxycillin.

METHODS

Forty-one healthy volunteers were given 500 mg amoxycillin twice daily for 7 days and were randomized to either 5 g of a multispecies probiotic, Ecologic AAD (10(9) cfu/g), or placebo, twice daily for 14 days. Feces and questionnaires were collected on day 0, 7, 14, and 63. Feces was analyzed as to the composition of the intestinal microbiota, and beta-glucosidase activity, endotoxin concentration, Clostridium difficile toxin A, short chain fatty acids (SCFAs), and pH were determined. Bowel movements were scored according to the Bristol stool form scale.

RESULTS

Mean number of enterococci increased significantly from log 4.1 at day 0 to log 5.8 (day 7) and log 6.9 (day 14) cfu/g feces (P < 0.05) during probiotic intake. Although no other significant differences were observed between both intervention groups, within each group significant changes were found over time in both microbial composition and metabolic activity. Moreover, bowel movements with a frequency >or=3 per day for at least 2 days and/or a consistency >or=5 for at least 2 days were reported less frequently in the probiotic compared to the placebo group (48%vs 79%, P < 0.05).

CONCLUSIONS

Apart from an increase in enterococci no significant differences in microbial composition and metabolic activity were observed in the probiotic compared with the placebo group. However, changes over time were present in both groups, which differed significantly between the probiotic and the placebo arm, suggesting that the amoxycillin effect was modulated by probiotic intake. Moreover, the intake of a multispecies probiotic significantly reduced diarrhea-like bowel movements in healthy volunteers receiving amoxycillin.

Enhanced production of phospholipase C and perfringolysin O (alpha and theta toxins) in a gatifloxacin-resistant strain of Clostridium perfringens

Clostridium perfringens-induced gas gangrene is mediated by potent extracellular toxins, especially alpha toxin (a phospholipase C [PLC]) and theta toxin (perfringolysin O [PFO], a thiol-activated cytolysin); and antibiotic-induced suppression of toxin synthesis is an important clinical goal. The production of PLC and PFO by a gatifloxacin-induced, fluoroquinolone-resistant mutant strain of C. perfringens, strain 10G, carrying a stable mutation in DNA gyrase was compared with that of the wild-type (WT) parent strain. Zymography (with sheep red blood cell and egg yolk overlays) and time course analysis [with hydrolysis of egg yolk lecithin and O-(4 nitrophenyl-phosphoryl)choline] demonstrated that strain 10G produced more PLC and PFO than the WT strain. Increased toxin production in strain 10G was not related either to differences in growth characteristics between the wild-type and the mutant strain or to nonsynonymous polymorphisms in PLC, PFO, or their known regulatory proteins. Increased PLC and PFO production by strain 10G was associated with increased cytotoxic activity for HT-29 human adenocarcinoma cells and with increased platelet-neutrophil aggregate formation. Four other gatifloxacin-induced gyrase mutants did not show increased toxin production, suggesting that gatifloxacin resistance was not always associated with increased toxin production in all strains of C. perfringens. This is the first report of increased toxin production in a fluoroquinolone-resistant strain of C. perfringens.

Review article: Probiotics in gastrointestinal and liver diseases

BACKGROUND

Probiotics, defined as live micro-organisms with beneficial effects for the host, are widely applied in gastrointestinal and liver diseases.

AIM AND METHOD

To review the available evidence of clinical trials on probiotics in gastrointestinal and liver diseases, with a major focus on irritable bowel syndrome, inflammatory bowel disease, pancreatitis and chronic liver diseases.

RESULTS

Evidence for the therapeutic or preventive application of particular probiotic strains is available for antibiotic-associated diarrhoea, rota-virus-associated diarrhoea and pouchitis. Results are encouraging for irritable bowel syndrome, ulcerative colitis and for reducing side effects by Helicobacter pylori eradication therapies, but are less clear for Crohn's disease, lactose intolerance and constipation. In general, for most of these patient groups, more placebo-controlled methodologically well-designed studies that pay attention to both clinical outcome and mechanistic aspects are required. The application in liver disease and pancreatitis is promising, but more human trials have to be awaited. Possible mechanisms of probiotics include modulation of the intestinal microbiota and the immune system, but different bacterial may have different effects.

CONCLUSION

Further insight into disease entities and the functioning of probiotic strains is required to be able to select disease-specific strains, which have to be tested in well-designed placebo-controlled studies.

Effect of a fermented milk combining Lactobacillus acidophilus Cl1285 and Lactobacillus casei in the prevention of antibiotic-associated diarrhea: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Antibiotic-associated diarrhea is an important problem in hospitalized patients. The use of probiotics is gaining interest in the scientific community as a potential measure to prevent this complication. The main objective of the present study was to assess the efficacy and safety of a fermented milk combining Lactobacillus acidophilus and Lactobacillus casei that is widely available in Canada, in the prevention of antibiotic-associated diarrhea.

METHODS

In this double-blind, randomized study, hospitalized patients were randomly assigned to receive either a lactobacilli-fermented milk or a placebo on a daily basis.

RESULTS

Among 89 randomized patients, antibiotic-associated diarrhea occurred in seven of 44 patients (15.9%) in the lactobacilli group and in 16 of 45 patients (35.6%) in the placebo group (OR 0.34, 95% CI 0.125 to 0.944; P=0.05). The median hospitalization duration was eight days in the lactobacilli group, compared with 10 days in the placebo group (P=0.09). Overall, the lactobacilli-fermented milk was well tolerated.

CONCLUSION

The daily administration of a lactobacilli-fermented milk was safe and effective in the prevention of antibiotic-associated diarrhea in hospitalized patients.

Antibiotic-associated diarrhoea

Diarrhoea is a common complication of antimicrobial therapy. The term antibiotic-associated diarrhoea (AAD) is often considered synonymous with Clostridium difficile. In fact, AAD can develop through a variety of mechanisms and manifest through a broad range of clinical signs and symptoms. For improved prevention and recognition of AAD, it is important to understand the pathophysiology and risk factors for AAD. Although Clostridium difficile continues to be the most common identifiable pathogen of AAD, many patients with AAD can be managed through a variety of conservative measures. This review focuses on some of the important distinctions between nonspecific AAD and antibiotic-associated colitis. In addition, the most recent data on important risk factors for the development of AAD are summarised. Given its pathogenicity, there will be an emphasis on the early diagnosis, treatment and prevention of Clostridium difficile-associated diarrhoea. AAD is a common clinical problem that can progress to severe, life-threatening disease if not recognised quickly. Better awareness of risk factors can lead to the most efficacious treatment of this disorder: primary prevention.

The emerging infectious challenge of clostridium difficile-associated disease in Massachusetts hospitals: clinical and economic consequences

OBJECTIVE

To estimate the clinical and economic burden of Clostridium difficile-associated disease (CDAD) in Massachusetts over 2 years.

DESIGN

A retrospective analysis of Massachusetts hospital discharge data from 1999-2003 was conducted. Cases of CDAD in 2000 were identified using code 008.45 from the International Classification of Diseases, Ninth Revision, Clinical Modification; patients were excluded if they had a hospitalization in the prior year during which a diagnosis of CDAD was recorded. Hospitalizations for CDAD during 2001 and 2002 were examined. For primary case patients (ie, those for which CDAD was the principal diagnosis), all inpatient costs were deemed to be related, whereas for secondary case patients, all-patient refined diagnosis-related group assignment, case severity level, and length of stay (LOS) were used to calculate incremental costs attributable to CDAD. Costs were adjusted to the national level and reported in 2005 US dollars.

RESULTS

The CDAD cohort consisted of 3,692 patients; 59% were women, and the mean age was 70 years. This group represented 1% of all patients hospitalized in Massachusetts in 2000 (96% of hospitals treated at least 1 case; range, 1-257 cases). Of patients who received a first hospital diagnosis of CDAD in 2000, a total of 28% were primary case patients; their mean LOS was 6.4 days, and the mean cost per stay was $10,212. For secondary case patients, the mean CDAD-related incremental LOS was 2.95 days, and the mean incremental cost per stay was $13,675 per patient. Of patients with CDAD who survived their index stay in 2000, a total of 455 (14%) had at least 1 readmission for CDAD within the subsequent 2 years (mean number of readmissions, 1.4 per patient; range, 1-7 readmissions), with a mean time to first readmission of 3 months. Over 2 years, a total of 55,380 inpatient-days and $51.2 million were consumed by CDAD management.

CONCLUSION

CDAD is widespread in Massachusetts hospitals. Rehospitalization with CDAD, if it occurs, generally happens within a few months and happens multiple times for some patients. Based on this study's findings, a conservative estimate of the annual US cost for CDAD management is $3.2 billion dollars.

Lactobacillus plantarum 299v enhances the concentrations of fecal short-chain fatty acids in patients with recurrent clostridium difficile-associated diarrhea

Our objective was to document how intake of Lactobacillus plantarum 299v affects the concentrations of fecal organic acids during and after metronidazole treatment in 19 patients with recurrent Clostridium difficile-associated diarrhea. Fecal samples were analyzed by gas-liquid chromatography. After intake of metronidazole a significant decrease in total short-chain fatty acids was seen in the placebo group (from 77.1 to 45.5 micromol/g; P=0.028) but not in the Lactobacillus group (79.8-60.4 micromol/g). In addition, a statistically significant difference between treatment groups was noted for butyrate (5.6-1.2 micromol/g in the placebo group vs. 7.6-5.6 micromol/g in the Lactobacillus group; P=0.047). At the end of the study and after cessation of placebo or Lactobacillus, the total short-chain fatty acids rose to the same levels as before antibiotic treatment in the placebo group. Both treatment groups showed a significant decrease in concentrations of succinate at the end of the study in comparison to the time when metronidazole intake was stopped (6.3-1.5 micromol/g in the placebo group versus 9.3-0.9 micromol/g in the Lactobacillus group; P=0.028). The present study of fecal samples from a clinical trial is the first to demonstrate that administration of Lactobacillus plantarum 299v reduces the negative effects of an antibiotic on colonic fermentation. The intake of this probiotic strain may thereby provide an additional benefit for patients with recurrent Clostridium difficile-associated diarrhea.

Prevention of antibiotic-associated diarrhoea by a fermented probiotic milk drink

OBJECTIVE

To study the preventive effect of a milk drink fermented with multistrain probiotics on antibiotic associated diarrhoea (AAD).

DESIGN

Double-blind placebo controlled study.

SETTING

University Hospital of North Norway.

SUBJECTS AND METHODS

Of 853 patients treated with antibiotics, 87 met the inclusion criteria, and were randomized to ingestion of a fermented milk drink containing LGG, La-5 and Bb-12 (n=46) or placebo with heat-killed bacteria (n=41), during a period of 14 days. A diary was recorded, and stool samples were collected for microbiological analyses.

RESULTS

Sixty-three patients completed the study according to the protocol; two patients (5.9%) in the treatment group and eight (27.6%) in the placebo group developed AAD (P=0.035). The relative risk of developing AAD was 0.21 (95% confidence interval: 0.05-0.93) when given probiotic milk drink.

CONCLUSION

A fermented multistrain probiotic milk drink may prevent four of five cases of AAD in adult hospitalized patients.

SPONSORSHIP

TINE BA, Oslo, Norway.

Review article: tolevamer, a novel toxin-binding polymer: overview of preclinical pharmacology and physicochemical properties

BACKGROUND

Tolevamer is a novel toxin-binding polymer that is currently being investigated in clinical trials for the treatment of patients who have Clostridium difficile-associated diarrhoea.

AIMS

To summarize the results of in vitro and in vivo preclinical studies of tolevamer. In contrast to antibiotics, tolevamer binds C. difficile toxins to interrupt toxin-mediated intestinal inflammation and tissue damage, and does not demonstrate direct antimicrobial activity.

METHODS

Pharmacokinetics/pharmacodynamics were studied in rats and dogs; efficacy was studied in a hamster model.

RESULTS

Studies in rats and dogs indicate that tolevamer is essentially non-absorbed from the gastrointestinal tract and show that drug interactions with commonly used therapies are unlikely. Pharmacologic studies indicate that tolevamer reduces disease severity and recurrence rates in the hamster model of C. difficile-associated diarrhoea and blocks the enterotoxic effects of toxin A in rat ileum. The binding parameters calculated for the interaction of tolevamer with toxins A and B provide a reasonable physicochemical model that supports the potential clinical utility of tolevamer.

CONCLUSIONS

These preclinical results are consistent with the effectiveness and safety profile of tolevamer observed in clinical studies in patients with C. difficile-associated diarrhoea.

Intestinal tract injury by drugs: Importance of metabolite delivery by yellow bile road

Drug secretion into bile is typically considered a safe route of clearance. However, biliary delivery of some drugs or their reactive metabolites to the intestinal tract evokes adverse consequences due to direct toxic actions or indirect disruption of intestinal homeostasis. Biliary concentration of the chemotherapy agent 5-fluorodeoxyuridine (FUDR) and other compounds is associated with bile duct damage while enterohepatic cycling of antibiotics contributes to the disruptions of gut flora that produce diarrhea. The goal of this review is to describe key evidence that biliary delivery is an important factor in the intestinal injury caused by representative drugs. Emphasis will be given to 3 widely used drugs whose reactive metabolites are plausible causes of small intestinal injury, namely the nonsteroidal anti-inflammatory drug (NSAID) diclofenac, the immunosuppressant mycophenolic acid (MPA), and the chemotherapy agent irinotecan. Capsule endoscopy and other sensitive diagnostic techniques have documented a previously unappreciated, high prevalence of small intestinal injury among NSAID users. Clinical use of MPA and irinotecan is frequently associated such severe intestinal injury that dosage must be reduced. Observations from clinical and experimental studies have defined key events in the pathogenesis of these drugs, including roles for multidrug resistance-associated protein 2 (MRP2) and other transporters in biliary secretion and adduction of enterocyte proteins by reactive acyl glucuronide metabolites as a likely mechanism for intestinal injury. New strategies for minimizing the adverse intestinal consequences of irinotecan chemotherapy illustrate how basic information about key events in the biliary secretion of drugs and the nature of their proximate toxicants can lead to safer protocols for drugs.

Risk factors for Clostridium difficile toxin-positive nosocomial diarrhoea

Data were retrieved from the records of all patients from whom stool was sent for Clostridium difficile toxin testing during the year 2001. Toxin-positive and -negative patients were compared by bivariate analysis and regression models. Eight hundred samples from 610 patients were sent for C. difficile toxin testing. Charts of 535 patients (88%) were available for analysis. Of those, 17% had a positive toxin test whilst 83% had a negative toxin test. There was no difference in the number of daily bowel movements between the two groups. Toxin-positive patients were older (P<0.0001), more often came from nursing homes (P<0.05), had higher leukocyte counts (P<0.001), higher blood urea nitrogen (P<0.01), lower serum albumin (P<0.01) and more often received diuretics (P<0.01) and clindamycin (P<0.05). Logistic regression analysis showed that previous antibiotic-associated diarrhoea was the most significant risk factor for toxin-positive diarrhoea (P<0.001), followed by clindamycin treatment (P<0.005), diuretics (P<0.005) and older age (P<0.05). Another logistic model showed the contribution of macrolides (P<0.05) to the development of hospital-acquired diarrhoea.

Diarrhea in neutropenic patients: a prospective cohort study with emphasis on neutropenic enterocolitis

BACKGROUND

Although diarrhea is a frequent complication in neutropenic patients, its true incidence, risk factors and clinical course have not been investigated prospectively.

PATIENTS AND METHODS

The study was carried out at Hacettepe University Hospital for Adults and involved patients over 16 years of age. Patients with malignant diseases who were neutropenic on admission or who became neutropenic during their stay in the wards between January 2001 and February 2003 were included. They were monitored daily until discharge, exitus, or recovery from neutropenia-whichever occurred earlier-to monitor the presence of diarrhea and other infections.

RESULTS

A total of 317 neutropenic episodes in 215 patients were followed. Diarrhea was observed in 18.6% episodes, and the incidence of NEC was 3.5%. The etiology in 27% episodes of diarrhea could not be identified. The use of anthracyclines and mitoxantrone increased the incidence of diarrhea. Prior use of penicillin derivatives plus beta-lactam inhibitors and N-imidazoline derivatives was associated with decreased incidence of diarrhea.

CONCLUSIONS

Diarrhea is a common complication in neutropenic patients. Not only specific conditions like NEC, but also nonspecific diseases like parasitosis may be the cause of diarrhea in this patient population.

Tolevamer, a novel nonantibiotic polymer, compared with vancomycin in the treatment of mild to moderately severe Clostridium difficile-associated diarrhea

BACKGROUND

Current antibiotic therapies for Clostridium difficile-associated diarrhea have limitations, including progression to severe disease, recurrent C. difficile-associated diarrhea, and selection for nosocomial pathogens. Tolevamer, a soluble, high-molecular weight, anionic polymer that binds C. difficile toxins A and B is a unique nonantibiotic treatment option.

METHODS

In this 3-arm, multicenter, randomized, double-blind, active-controlled, parallel-design phase II study, patients with mild to moderately severe C. difficile-associated diarrhea were randomized to receive 3 g of tolevamer per day (n = 97), 6 g of tolevamer per day (n = 95), or 500 mg of vancomycin per day (n = 97). The primary efficacy parameter was time to resolution of diarrhea, defined as the first day of 2 consecutive days when the patient had hard or formed stools (any number) or < or = 2 stools of loose or watery consistency.

RESULTS

In the per-protocol study population, resolution of diarrhea was achieved in 48 (67%) of 72 patients receiving 3 g of tolevamer per day (median time to resolution of diarrhea, 4.0 days; 95% confidence interval, 2.0-6.0 days), in 58 (83%) of 70 patients receiving 6 g of tolevamer per day (median time to resolution of diarrhea, 2.5 days; 95% confidence interval, 2.0-3.0 days), and in 73 (91%) of 80 patients receiving vancomycin (median time to resolution of diarrhea, 2.0 days; 95% confidence interval, 1.0-3.0 days). Tolevamer administered at a dosage of 6 g per day was found to be noninferior to vancomycin administered at a dosage of 500 mg per day with regard to time to resolution of diarrhea (P = .02) and was associated with a trend toward a lower recurrence rate. Tolevamer was well tolerated but was associated with an increased risk of hypokalemia.

CONCLUSIONS

Tolevamer, a novel polystyrene binder of C. difficile toxins A and B, effectively treats mild to moderate C. difficile diarrhea and merits further clinical development.

Rapid detection of enterotoxigenic clostridium perfringens by real-time fluorescence resonance energy transfer PCR

Clostridium perfringens is one of the etiologic agents of gas gangrene that can occur when a wound is contaminated with soil. Type A C. perfringens can cause foodborne and nonfoodborne gastrointestinal illnesses due to an enterotoxin (CPE) produced by some strains during sporulation. We developed a quantitative real-time PCR assay based on fluorescence resonance energy transfer hybridization chemistry that targets the C. perfringens-specific phospholipase C (plc) gene and the enterotoxigenic gene (cpe) with the LightCycler and the Ruggedized Advanced Pathogen Identification Device (R.A.P.I.D.). The assay can detect as few as 20 copies of target sequences per PCR. The total assay time, from extraction to PCR analysis, is 90 min. This assay is rapid, sensitive, and specific and will allow direct detection of C. perfringens in water, food, and stool samples. It should prove helpful in investigating foodborne illnesses due to C. perfringens and can be used as a tool to ensure the safety of food and water supplies.

Challenges in the addition of probiotic cultures to foods

Probiotic cultures are increasingly being added to foods in order to develop products with health-promoting properties. Although the literature is abundant on the beneficial effects of bifidobacteria and Lactobacillus acidophilus on health, little information is available on the challenges industry faces in adding these probiotic cultures to food products. The aim of this article is to examine seven issues that should be addressed when developing functional foods: 1) type or form of probiotic that should be used; 2) addition level required to have a beneficial effect; 3) toxicity; 4) effect of the processing steps on viability; 5) determination, in the product, of the cell populations added; 6) stability during storage; 7) changes in sensory properties of the foods.

Probiotics in gastrointestinal diseases in children: hard and not-so-hard evidence of efficacy

The use of probiotics, once discussed primarily in the context of alternative medicine, is now entering mainstream medicine. However, only a few of the potential health benefits attributed to probiotics have been confirmed in well-designed, well-conducted, randomized, controlled trials. This is especially true in the pediatric population. We review here the available evidence on efficacy of probiotics in children in the prevention and treatment of gastrointestinal diseases. Although we restrict our analysis to the pediatric age, whenever potentially relevant information is available only from adult studies, they are examined as well. Probiotics have been most extensively studied in the treatment of diarrheal diseases, where their efficacy can be considered well established. Studies documenting effects in other childhood gastrointestinal illnesses are few, although some preliminary results are promising. Furthermore, only a limited number of probiotic strains have been tested, and, as the effects of different probiotic microorganisms are not equivalent, results cannot be generalized. Thus, at present, we have some positive certainties, lots of exciting promises and many unanswered questions.

Effect of a milk formula with prebiotics on the intestinal microbiota of infants after an antibiotic treatment

Antibiotics exert deleterious effects on the intestinal microbiota, favoring the emergence of opportunistic bacteria and diarrhea. Prebiotics are nondigestible food components that stimulate the growth of bifidobacteria. Our aim was to evaluate the effects on the intestinal microbiota of a prebiotic-supplemented milk formula after an antibiotic treatment. A randomized, double-blind, controlled clinical trial was carried out in 140 infants 1-2 y of age distributed into two groups after a 1-wk amoxicillin treatment (50 mg/kg/d) for acute bronchitis. The children received for 3 wk >500 mL/d of a formula with prebiotics (4.5 g/L) or a control without prebiotics. Fecal samples were obtained on d -7 (at the beginning of the antibiotic treatment), on d 0 (end of the treatment and before formula administration), and on d 7 and 21 (during formula administration). Counts of Bifidobacterium, Lactobacillus-Enterococcus, Clostridium lituseburiense cluster, Clostridium histolyticum cluster, Escherichia coli, and Bacteroides-Prevotella were evaluated by fluorescent in situ hybridization (FISH) and flow cytometry. Tolerance and gastrointestinal symptoms were recorded daily. Amoxicillin decreased total fecal bacteria and increased E. coli. The prebiotic significantly increased bifidobacteria from 8.17 +/- 1.46 on d 0 to 8.54 +/- 1.20 on d 7 compared with the control 8.22 +/- 1.24 on d 0 versus 7.95 +/- 1.54 on d 7. The Lactobacillus population showed a similar tendency while the other bacteria were unaffected. No gastrointestinal symptoms were detected during the prebiotic administration. Prebiotics in a milk formula increase fecal bifidobacteria early after amoxicillin treatment without inducing gastrointestinal symptoms.

Molecular analysis of jejunal, ileal, caecal and recto-sigmoidal human colonic microbiota using 16S rRNA gene libraries and terminal restriction fragment length polymorphism

Microbiota in gut contents of jejunum, ileum, caecum and recto-sigmoid colon obtained from three elderly individuals at autopsy were compared using 16S rRNA gene libraries and terminal restriction fragment length polymorphism (T-RFLP). Random clones of 16S rRNA gene sequences were isolated after PCR amplification with universal primer sets of total genomic DNA extracted from each sample of gut contents. An average of 90 randomly selected clones were partially sequenced (about 500 bp). T-RFLP analysis was performed using the 16S rRNA gene amplified from each sample. The lengths of the terminal restriction fragments were analysed after digestion with HhaI and MspI. The jejunal and ileal microbiota consisted of simple microbial communities of streptococci, lactobacilli, 'Gammaproteobacteria', the Enterococcus group and the Bacteroides group. Most of the species were facultative anaerobes or aerobes. The Clostridium coccoides group and the Clostridium leptum subgroup, which are the most predominant groups in human faeces, were not detected in samples from the upper gastrointestinal tract. The caecal microbiota was more complex than the jejunal and ileal microbiota. The C. coccoides group, the C. leptum subgroup and the Bacteroides group were detected in the caecum. The recto-sigmoidal colonic microbiota consisted of complex microbial communities, with numerous species that belonged to the C. coccoides group, the C. leptum subgroup, the Bacteroides group, 'Gammaproteobacteria', the Bifidobacterium group, streptococci and lactobacilli, and included more than 26 operational taxonomic units. The results showed marked individual differences in the composition of microbiota in each region.

Diarrhea caused by primarily non-gastrointestinal infections

Direct infections of the gastrointestinal tract cause most cases of diarrhea, but diarrhea can also be caused by systemic infections or infections that affect other organ systems. The authors of this Review discuss clinically relevant infectious diseases that do not primarily affect the gastrointestinal tract but commonly cause diarrhea, and note that they should be included in the differential diagnosis and diagnostic approach to diarrhea.

Infectious diseases that do not primarily affect the gastrointestinal tract can cause severe diarrhea. The pathogenesis of this kind of diarrhea includes cytokine action, intestinal inflammation, sequestration of red blood cells, apoptosis and increased permeability of endothelial cells in the gut microvasculature, and direct invasion of gut epithelial cells by various infectious agents. Of the travel-associated systemic infections presenting with fever, diarrhea occurs in patients with malaria, dengue fever and SARS. Diarrhea also occurs in patients with community-acquired pneumonia, when it is suggestive of legionellosis. Diarrhea can also occur in patients with systemic bacterial infections. In addition, although diarrhea is rare in patients with early Lyme borreliosis, the incidence is higher in those with other tick-borne infections, such as ehrlichiosis, tick-borne relapsing fever and Rocky Mountain spotted fever. Unfortunately, it is often not established whether diarrhea is an initial symptom or develops during the course of the disease. The real incidence of diarrhea in some infectious diseases must also be questioned because it could represent an adverse reaction to antibiotics.

Nosocomial antibiotic-associated diarrhea associated with enterotoxin-producing strains of methicillin-resistant Staphylococcus aureus

OBJECTIVES

The aim of this study is to present new evidence that enterotoxin-producing strains of methicillin-resistant Staphylococcus aureus may cause nosocomial antibiotic-associated diarrhea.

METHODS

We conducted a prospective study that utilized standard methods to exclude other bacterial, parasitic, and viral pathogens as causes of nosocomial diarrhea in patients with heavy growth of methicillin-resistant S. aureus in their stool. Staphylococcal enterotoxin assays were performed on S. aureus strains recovered from patients' stools and on stool specimens from affected patients. Retrospective cohort studies compared the severity of diarrhea in patients with methicillin-resistant S. aureus-associated diarrhea with that of patients whose stool did not contain the organism and with patients colonized or infected with enterotoxin-negative methicillin-resistant S. aureus strains.

RESULTS

During an 18-month period, 11 patients had nosocomial antibiotic-associated diarrhea associated with enterotoxin-producing strains of methicillin-resistant S. aureus. Other common bacterial, parasitic, and viral pathogens were excluded. S. aureus strains from the 11 patients produced staphylococcal enterotoxin A, A and B, or D. Eighty-nine percent of patients had the same enterotoxin(s) in stool specimens as produced by the strain recovered from their stool. Case patients had a greater number of days of diarrhea than patients without methicillin-resistant S. aureus in their stool (p < 0.001), or randomly selected patients colonized or infected with enterotoxin-negative methicillin-resistant S. aureus (p < 0.001).

CONCLUSIONS

Our findings provide evidence that enterotoxin-producing strains of methicillin-resistant S. aureus may cause nosocomial antibiotic-associated diarrhea. Greater recognition of this disease should result in more rapid and appropriate treatment of affected patients.

Antibiotic-associated diarrhea in a Turkish outpatient population: investigation of 288 cases

Oral antibiotics are often prescribed, especially for respiratory tract infections in the community. The widespread use of broad-spectrum antibiotics causes an increased incidence of antibiotic-associated diarrhea (AAD). Although AAD has been studied in hospitalized patients, there is little available information concerning the characteristics of AAD in outpatient populations. The aim of this study was to investigate the clinical and laboratory findings of adult patients with community-acquired AAD. Between June 1998 and December 2003, the clinical reports of 288 patients were retrospectively reviewed. We observed that the duration between the start of antibiotic treatment and onset of symptoms was 7 days in most of the patients (86%), and the mean time was 9+/-1.0 days. The diarrhea was self-limited in all cases and mean duration of symptoms was 3 (+/-1.0) days (1-7 days). The most common symptoms were abdominal discomfort and tenesmus (61.1%), while elevated WBC counts and fever were detected rarely. We were able to perform microbiologic investigations in only 88 patients because of the financial problems. Of the 88 stool specimens tested, none of them were positive for pathogenic bacterial growth or toxin A production.

Antibiotic-associated diarrhea and pseudomembranous colitis: are they less common with poorly absorbed antimicrobials?

Diarrhea is a well-known complication of antibiotic therapy. Rates of antibiotic-associated diarrhea (AAD) vary from 5 to 25%. Some antibiotics are more likely to cause diarrhea than others, specifically, those that are broad spectrum and those that target anaerobic flora. This paper reviews the effects of antibiotics on the fecal flora as well as host factors which contribute to AAD. Clinical features and treatment of AAD are also described. Prevention of AAD rests on wise antibiotic policies, the use of probiotics and prevention of acquisition in the hospital setting. Data from clinical trials suggest that poorly absorbed antimicrobials might have a decreased risk of causing AAD and Clostridium difficile-associated disease, as concluded from studies of antibiotics used for preoperative bowel decontamination and poorly absorbed antibiotics used for traveler's diarrhea. Controlled trials would prove this but are not yet available. Probiotics may be a good adjunct to poorly absorbed antibiotics to minimize the risk of diarrhea associated with antibiotics.

A Pseudomonas aeruginosa quorum-sensing molecule influences Candida albicans morphology

Candida albicans is an opportunistic pathogen that is commonly found as a member of the human microflora. The ability of C. albicans to alter its cellular morphology has been associated with its virulence; yeast cells are more prevalent in commensal interactions whereas filamentous cells appear important in opportunistic infections. C. albicans encounters a multitude of other microbial species in the host environment and it is likely that they impact the C. albicans transition between virulent and non-virulent states. Here, we report that C. albicans morphology is significantly affected by the presence of Pseudomonas aeruginosa, another opportunistic pathogen. In a screen using a C. albicans HWP1-lacZ strain to indicate regions of filamentous growth, we identified P. aeruginosa mutants incapable of inhibiting C. albicans filamentation. Through these studies, we found that 3-oxo-C12 homoserine lactone, a cell-cell signalling molecule produced by P. aeruginosa, was sufficient to inhibit C. albicans filamentation without affecting fungal growth rates. Both microscopic analysis and real-time reverse transcription polymerase chain reaction analysis of morphology-specific markers confirmed that filamentation was suppressed by 200 microM 3-oxo-C12 homoserine lactone. Structurally related compounds with a 12-carbon chain length, e.g. C12-acyl homoserine lactone and dodecanol also affected C. albicans filamentation at similar concentrations. In contrast, other acylated homoserine lactones of different chain lengths did not affect fungal morphology. The activity of 3OC12HSL is compared with that of farnesol, a C. albicans-produced molecule also with a C12-backbone. The effects that bacteria have on the morphology of C. albicans represents one of the ways by which bacteria can influence the behaviour of fungal cells.

Influence of antimicrobial treatment for Helicobacter pylori infection on the intestinal microflora in Japanese macaques

Eradication treatment for Helicobacter pylori is known to cause mild but relatively frequent adverse effects. Some adverse effects such as diarrhoea and soft stools are related to disruption of the composition of the intestinal microflora. This study investigated the microfloral changes resulting from administration of an eradication regimen using proton pump inhibitor (PPI), amoxycillin and clarithromycin. Twenty-eight laboratory-bred Japanese macaques either were administered eradication treatment by this regimen for 7 days or received no medication. Faecal samples were collected for analysis on days 0, 8 and 15, and both aerobic and anaerobic cultures were performed. Among aerobic bacteria, Streptococcus had significantly decreased by day 8, while Enterococcus and Enterobacteriaceae had significantly increased. However, the total number of aerobic bacteria was not significantly decreased from pretreatment levels 1 day after completion of treatment. The number of anaerobic bacteria did not change significantly by day 8. However, the number of Lactobacillus and the detection rate of Bifidobacterium, Peptostreptococcus and Veillonella significantly decreased by day 8, although the number of Bifidobacterium, Peptostreptococcus and Veillonella had almost recovered up to the pretreatment levels 1 week after completion of treatment (day 15). These results suggest that the alterations in the composition of the intestinal microflora caused by the antimicrobial regimen that excludes metronidazole are different from those caused by the regimen including this drug. However, the alterations in bacterial microflora had almost reversed 7 days after completion of treatment in these macaques, which supports clinical findings that diarrhoea or soft stools in humans resolve relatively quickly after a similar treatment.

Saccharomyces boulardii in the prevention of antibiotic-associated diarrhoea in children: a randomized double-blind placebo-controlled trial

BACKGROUND

Co-treatment with Saccharomyces boulardii appears to lower the risk of antibiotic-associated diarrhoea in adults receiving broad-spectrum antibiotics.

AIM

To determine whether S. boulardii prevents antibiotic-associated diarrhoea in children.

METHODS

A total of 269 children (aged 6 months to 14 years) with otitis media and/or respiratory tract infections were enrolled in a double-blind, randomized placebo-controlled trial in which they received standard antibiotic treatment plus 250 mg of S. boulardii (experimental group, n = 132) or a placebo (control group, n = 137) orally twice daily for the duration of antibiotic treatment. Analyses were based on allocated treatment and included data from 246 children.

RESULTS

Patients receiving S. boulardii had a lower prevalence of diarrhoea (> or =3 loose or watery stools/day for > or =48 h occurring during or up to 2 weeks after the antibiotic therapy) than those receiving placebo [nine of 119 (8%) vs. 29 of 127 (23%), relative risk: 0.3, 95% confidence interval: 0.2-0.7]. S. boulardii also reduced the risk of antibiotic-associated diarrhoea (diarrhoea caused by Clostridium difficile or otherwise unexplained diarrhoea) compared with placebo [four of 119 (3.4%) vs. 22 of 127 (17.3%), relative risk: 0.2; 95% confidence interval: 0.07-0.5]. No adverse events were observed.

CONCLUSION

This is the first randomized-controlled trial evidence that S. boulardii effectively reduces the risk of antibiotic-associated diarrhoea in children.