Randomised clinical trial: faecal microbiota transplantation for recurrent Clostridum difficile infection - fresh, or frozen, or lyophilised microbiota from a small pool of healthy donors delivered by colonoscopy

BACKGROUND

Faecal microbiota transplantation (FMT) has become routine in managing recurrent C. difficile infection (CDI) refractory to antibiotics.

AIM

To compare clinical response and improvements in colonic microbiota diversity in subjects with recurrent CDI using different donor product.

METHODS

Seventy-two subjects with ≥3 bouts of CDI were randomised in a double-blind study to receive fresh, frozen or lyophilised FMT product via colonoscopy from 50 g of stool per treatment from eight healthy donors. Recipients provided stools pre- and 7, 14 and 30 days post-FMT for C. difficile toxin and, in a subset, microbiome composition by 16S rRNA gene profiling.

RESULTS

Overall resolution of CDI was 87% during 2 months of follow-up after FMT. Stool samples before FMT had significantly decreased bacterial diversity with a high proportion of Proteobacteria compared to donors. Cure rates were highest for the group receiving fresh product seen in 25/25 (100%), lowest for the lyophilised product 16/23 (78%; P = 0.022 vs. fresh and 0.255 vs. frozen) and intermediate for frozen product 20/24 (P = 0.233 vs. fresh). Microbial diversity was reconstituted by day 7 in the subjects receiving fresh or frozen product. Improvement in diversity was seen by day 7 in those randomised to lyophilised material with reconstitution by 30 days.

CONCLUSIONS

Comparative efficacy in faecal microbiota transplantation was observed in subjects receiving fresh or frozen faecal product from the same donors. The lyophilised product had a slightly lowered efficacy compared with fresh product, but it resembled other treatments in microbial restoration 1 month after faecal microbiota transplantation.

Etiology of travellers' diarrhea

Eleven published studies of the etiology of travellers' diarrhea (TD) were reviewed define the etiology of TD and to exam newly developed technology such as Real-Time multiplex polymerase chain reaction (PCR) to identify multiple pathogens in one assay to define the cause of TD. Using PCR methods bacterial pathogens were found in 72% of patients acquiring diarrhea in Latin America and in 80% in travellers with illness acquired in Southeast Asia). In these studies, enterotoxigenic Escherichia coli as the predominant pathogen (42% in Latin America and 28% in Southeast Asia). Ciprofloxacin-resistant Campylobacter was commonly associated with TD in Southeast Asia. Multiplex PCR has improved the detection of enteropathogens and allowed better assessment returning travellers hospitalized with TD and those with persistent diarrhea.

Rifaximin: An Antibiotic with Important Biologic Effects

Rifaximin is a poorly absorbed rifamycin drug with unique pharmacokinetic properties: bile solubility making it highly active against pathogenic and non-pathogenic bacterial flora in the bile-rich small bowel and low water solubility making it active only against highly susceptible bacteria, primarily anaerobes, in the aqueous colon. The drug has anti-inflammatory gut mucosal stabilization properties that are important to its sustained effects in non-infectious diseases. Rifaximin is used chronically or recurrently for hepatic encephalopathy and diarrhea-predominant irritable bowel syndrome. Monitoring of long-term use of rifaximin for development of resistance and then determining whether developed resistance is associated with reduced efficacy are needed. Studies of changes of intestinal flora during therapy and the health implications of these changes are also needed.

Economic burden of primary compared with recurrent Clostridium difficile infection in hospitalized patients: a prospective cohort study

BACKGROUND

Few studies have investigated the additional healthcare costs of recurrent C. difficile infection (CDI).

AIM

To quantify inpatient treatment costs for CDI and length of stay among hospitalized patients with primary CDI only, compared with CDI patients who experienced recurrent CDI.

METHODS

This was a prospective, observational cohort study of hospitalized adult patients with primary CDI followed for three months to assess for recurrent CDI episodes. Total and CDI-attributable hospital length of stay (LOS) and hospitalization costs were compared among patients who did or did not experience at least one recurrent CDI episode.

FINDINGS

In all, 540 hospitalized patients aged 62±17 years (42% males) with primary CDI were enrolled, of whom 95 patients (18%) experienced 101 recurrent CDI episodes. CDI-attributable median (interquartile range) LOS and costs (in US$) increased from 7 (4-13) days and $13,168 (7,525-24,456) for patients with primary CDI only versus 15 (8-25) days and $28,218 (15,050-47,030) for patients with recurrent CDI (P<0.0001, each). Total hospital median LOS and costs increased from 11 (6-22) days and $20,693 (11,287-41,386) for patients with primary CDI only versus 24 (11-48) days and $45,148 (20,693-82,772) for patients with recurrent CDI (P<0.0001, each). The median cost of pharmacological treatment while hospitalized was $60 (23-200) for patients with primary CDI only (N=445) and $140 (30-260) for patients with recurrent CDI (P=0.0013).

CONCLUSION

This study demonstrated that patients with CDI experience a significant healthcare economic burden attributed to CDI. Economic costs and healthcare burden increased significantly for patients with recurrent CDI.

Review article: the antimicrobial effects of rifaximin on the gut microbiota

BACKGROUND

Disruption of the gut microbiota through use of systemic antimicrobials or activation of the mucosal inflammatory response by pathogens can cause dysregulation of the intestinal mucosa.

AIM

To explore the mechanisms of action of rifaximin that may underlie its clinical benefits in travellers' diarrhoea (TD).

METHODS

A literature search was performed using the terms 'rifaximin' and 'L/105' in combination with the terms 'in vitro activity', 'diarrhea', 'microbiota' and 'gut flora'.

RESULTS

Rifaximin has been traditionally identified as a nonsystemic, broad-spectrum, bactericidal antibiotic. Evidence shows that the activity of rifaximin against enteropathogens in this setting is likely enhanced by its increased solubility in the presence of bile acids in the small intestine. Results of clinical studies show that although rifaximin is efficacious in TD, a clinical cure often occurs without apparent bacterial eradication and with minimal effect on the gut microbiota, suggesting an effect of rifaximin other than direct antibiotic activity.

CONCLUSIONS

Although definitive studies on the effect of rifaximin on the gut microbiota in large cohorts of healthy volunteers or patients have not been published, pre-clinical studies provide some insight. These studies have shown that rifaximin may have effects on both the pathogen and host, including direct effects on pathogenic bacteria (such as reducing the expression of bacterial virulence factors) and indirect effects on the host (such as inhibiting bacterial attachment and internalisation at the intestinal mucosa and reducing mucosal inflammation).

Introduction: understanding mechanisms of the actions of rifaximin in selected gastrointestinal diseases

BACKGROUND

Historically, the beneficial effects of the nonsystemic oral agent rifaximin on various gastrointestinal (GI) disorders have been attributed to direct antibiotic activity on gut microbiota. However, data are accumulating to suggest that other nonantibacterial effects may be involved in rifaximin efficacy.

AIM

To explore the mechanisms of action of rifaximin that may underlie its clinical benefits in travellers' diarrhoea, hepatic encephalopathy and other cirrhosis complications, inflammatory bowel diseases, and irritable bowel syndrome with diarrhoea.

METHODS

Gastroenterology experts convened a round-table discussion to address clinical and pre-clinical rifaximin data pertaining to select GI diseases and the potential mechanisms of action that underlie rifaximin efficacy profiles. As preparation, the literature was searched for publications related to rifaximin, its mechanisms of action, and its efficacy in travellers' diarrhoea, hepatic encephalopathy and other cirrhosis-related complications, inflammatory bowel diseases and irritable bowel syndrome.

RESULTS

Gut microbiota dysbiosis and proinflammatory activities are thought to significantly contribute to disease pathophysiology of these conditions. Rifaximin may resolve gut microbiota dysbiosis by promoting GI colonisation of beneficial bacterial species without drastic alterations in overall diversity. Rifaximin-induced changes in the production and metabolism of bacteria-produced agents (e.g. deoxycholic acid, lipopolysaccharides) also may help preserve normal gut microbiota. Rifaximin may suppress local and systemic inflammatory processes by preserving epithelial function (e.g. limiting bacterial translocation), modulating bacterial virulence and reducing proinflammatory cytokine production.

CONCLUSION

The commonality of pathological mechanisms underlying multiple GI diseases and the ability of rifaximin to modulate the gut microenvironment (i.e. gut microenvironment modulator) may explain its diverse efficacy profile.

The Short- and Long-term Effects of a Handbook on Antimicrobial Prescribing Patterns of Hospital Physicians

This study evaluates the effect of a specially designed, physician-oriented handbook of antimicrobial use on the prescribing patterns of a group of 50 doctors at a university hospital. Data were evaluated over a period of one-and-one-half years, before and after the distribution of the handbook. For the purposes of this study, antimicrobial therapy was classified: 1) inappropriate if it violated one of a number of recognized principles of antimicrobial therapy, 2) appropriate if it agreed with specific recommendations or alternatives given in the distributed reference handbook, and 3) acceptable if it was neither inappropriate nor appropriate as defined by the handbook. An initial survey of antimicrobial prescribing patterns was made. Five months later the handbook was distributed. A two-week orientation program, consisting of the distribution and promotion of the problem-oriented, pocket-sized handbook of appropriate antimicrobial therapy, was conducted. The handbook, which was developed by the authors and reviewed and approved by a panel of infectious disease specialists, presented guidelines for appropriate and efficacious usage of antimicrobial agents as most currently accepted in common clinical infections. Subsequent surveys were then conducted two weeks, three months, and six months after distribution of the handbook. A statistically significant difference (p <0.01) in antimicrobial prescribing patterns was noted between the survey conducted two weeks after the introduction of the handbook and the other surveys. In this survey, while therapy classified inappropriate decreased from 45% to 28%, therapy considered appropriate as recommended increased from 33% to 53%. The findings of this study demonstrated that the introduction and promotion of the handbook decreased abuse and increased proper use of antimicrobial therapy, although the effect is sustainable for only a short duration—no longer than three months. These results indicate the need for a vigorous, updated program to achieve and maintain current appropriate antibiotic therapy in clinical medicine.

Clostridium difficile infection in hospitalized cancer patients in Beijing, China is facilitated by receipt of cancer chemotherapy

The purpose of this study was to determine the presence of Clostridium difficile infection (CDI) and risk factors for infection in hospitalized patients with diarrhea in a cancer hospital in Beijing, China. A total of 277 patients with hospital-associated diarrhea (HAD) were studied of which 41 (15%) were positive for fecal C. difficile toxin A/B. For each CDI case identified, a control with HAD but negative C. difficile specimen was enrolled to look for CDI risk factors. Receipt of cancer chemotherapy occurred in 20 (49%) patients with CDI and 9 (22.0%) patients with non-CDI HAD (OR3.39, 95%CI 1.78-10.05). Median length of chemotherapy before HAD developed was 39 days for those with CDI and 22 days for patients with CDI-negative HAD (P = 0.0391). The study found that CDI is commonly seen in cancer patients in China with increasing risk for patients who receive chemotherapy.

In vitro susceptibility of Clostridium difficile to rifaximin and rifampin in 359 consecutive isolates at a university hospital in Houston, Texas

AIM

This was an in vitro study to analyse the susceptibility of Clostridium difficile isolates to rifampin and rifaximin.

METHODS

Stool samples from patients who had nosocomial diarrhoea and C difficile toxin B at a university hospital between August 2006 and December 2007 were cultured for C difficile. Susceptibility of C difficile isolates to rifaximin and rifampin was determined by agar dilution and E strips, respectively. C difficile isolates were analysed via PCR for genes encoding toxins A and B, for binary toxin (BT), and for partial deletions of the tcdC gene (tcdC-del).

RESULTS

Rifaximin exhibited high-level activity against 359 C difficile isolates, with MIC(50) <0.01 microg/ml and MIC(90) 0.25 microg/ml; rifampin had MIC(50) <0.002 microg/ml and MIC(90) 4 microg/ml. Among isolates analysed, 55 (15%) were positive for BT and tcdC-del. 28 (8% of 359) isolates were resistant to rifampin (> or = 32 microg/ml), of which 6 (2% of 359) were resistant to rifaximin and rifampin with MIC values > or = 32 microg/ml. 2 of the 28 isolates resistant to rifampin were A(+)/B(+)/BT(+)/tcdC-del(+), 5 were A(+)/B(+)/BT(-)/tcdC-del(+), 4 were A(+)/B(+)/BT(+)/tcdC-del(-), 13 were A(+)/B(+)/BT(-)/tcdC-del(-), and 4 had no detectable toxin genes. Of the 11 isolates resistant to rifaximin alone, 1 was A(+)/B(+)/BT(-)/tcdC-del(+), 2 were A(+)/B(+)/BT(+)/tcdC-del(-), 6 were A(+)/B(+)/BT(-)/tcdC-del(-), and 2 had no detectable toxin genes.

CONCLUSIONS

The study demonstrates that rifaximin has high-level activity against C difficile in vitro. Determination of resistance to rifampin by E strip did not predict rifaximin resistance.

Economic healthcare costs of Clostridium difficile infection: a systematic review

Clostridium difficile infection (CDI) is the leading cause of infectious diarrhoea in hospitalised patients. CDI increases patient healthcare costs due to extended hospitalisation, re-hospitalisation, laboratory tests and medications. However, the economic costs of CDI on healthcare systems remain uncertain. The purpose of this study was to perform a systematic review to summarise available studies aimed at defining the economic healthcare costs of CDI. We conducted a literature search for peer-reviewed studies that investigated costs associated with CDI (1980 to present). Thirteen studies met inclusion and exclusion criteria. CDI costs in 2008 US dollars were calculated using the consumer price index. The total and incremental costs for primary and recurrent CDI were estimated. Of the 13, 10 were from the USA and one each from Canada, UK, and Ireland. In US-based studies incremental cost estimates ranged from $2,871 to $4,846 per case for primary CDI and from $13,655 to $18,067 per case for recurrent CDI. US-based studies in special populations (subjects with irritable bowel disease, surgical inpatients, and patients treated in the intensive care unit) showed an incremental cost range from $6,242 to $90,664. Non-US-based studies showed an estimated incremental cost of $5,243 to $8,570 per case for primary CDI and $13,655 per case for recurrent CDI. Economic healthcare costs of CDI were high for primary and recurrent cases. The high cost associated with CDI justifies the use of additional resources for CDI prevention and control.

Systematic review: the epidemiology and clinical features of travellers' diarrhoea

BACKGROUND

Travellers' diarrhoea is the most common medical complaint among persons venturing into developing areas from industrialized regions.

AIM

To review recent developments dealing with microbiological, clinical, pathophysiological and therapeutic aspects of travellers' diarrhoea.

METHODS

The author's extensive file plus a review of publications listed in PubMed on January 22, 2009 on the topic of travellers' diarrhoea were reviewed.

RESULTS

Travellers' diarrhoea is largely caused by detectable and undetected bacterial enteropathogens, explaining the remarkable effectiveness of antibacterial agents in prophylaxis and therapy of the illness. A number of host genetic polymorphisms have been recently linked with susceptibility to travellers' diarrhoea. Novel antisecretory agents are being developed for treatment considering their physiological effects in acute diarrhoea. All travellers should be armed with one of three antibacterial drugs, ciprofloxacin, rifaximin or azithromycin, before their trips to use in self therapy should diarrhoea occur during travel. Loperamide may treat milder forms of travellers' diarrhoea and can be employed with antibacterial drugs.

CONCLUSIONS

Diarrhoea will continue to plague international travellers to high-risk regions. More studies of the incidence rate, relative important of the various pathogens by geographical region of the world, host risk factors and optimal therapeutic approach are needed.

Automated system to identify Clostridium difficile infection among hospitalised patients

The purpose of this study was to assess whether data on stool frequency collected electronically could identify patients at high risk for Clostridium difficile infection (CDI). All patients with reports of diarrhoea were assessed prospectively for number of stools per day and number of diarrhoea days. C. difficile testing was requested independently from study investigators. Number of days with diarrhoea and maximum number of unformed stools was assessed as a CDI predictor. A total of 605 patients were identified with active diarrhoea of whom 64 (10.6%) were diagnosed with CDI. In univariate analysis, the maximum number of stools and number of diarrhoea days was associated with increased risk of CDI. Compared to patients with three diarrhoea stools per day (CDI incidence: 6.3%), CDI increased to 13.4% in patients with four or more diarrhoea stools per day [odds ratio (OR): 2.3; 95% confidence interval (CI): 1.3-4.2; P=0.0054]. Compared to patients with one day of diarrhoea (CDI incidence: 6.3%), CDI increased to 17.4% in patients with two diarrhoea days (OR: 3.1; 95% CI: 1.7-5.6) and to 27.1% in patients with three or more diarrhoea days (OR: 5.5; 95% CI: 2.6-11.7). These results were validated using logistic regression with number of days with diarrhoea identified as the most important predictor. Using an electronic data capture technique, number of days of diarrhoea and maximum number of diarrhoea stools in a 24h time period were able to identify a patient population at high risk for CDI.

Meta-analysis to assess risk factors for recurrent Clostridium difficile infection

SUMMARY

Clostridium difficile infection (CDI) is the most common cause of hospital-acquired diarrhoea. It is estimated that 15-20% of patients experience recurrence of CDI. A limited number of studies have looked at the risk factors for recurrent CDI. We conducted a meta-analysis of observational studies and randomised controlled trials (RCTs) to assess risk factors for recurrent CDI. Studies were identified using the PubMed database and search terms 'Clostridium difficile associated diarrhoea' or 'pseudomembranous colitis'. Both observational studies and RCTs were included. In all, 1215 studies were identified of which 48 met the inclusion criteria. Twelve studies involving 1382 patients with CDI met the complete eligibility requirements. Odds ratios and information on study quality were abstracted by two investigators independently. To be included in the analysis, each risk factor was required to be evaluated by at least three separate studies. Continued use of non-C. difficile antibiotics after diagnosis of CDI (OR: 4.23; 95% CI: 2.10-8.55; P<0.001), concomitant receipt of antacid medications (OR: 2.15; 95% CI: 1.13-4.08; P=0.019), and older age (OR: 1.62; 95% CI: 1.11-2.36; P=0.0012) were significantly associated with increased risk of recurrent CDI. Significant prognostic risk factors were identified as risk factors for CDI recurrence. Additional or novel interventions may be required for these patients to prevent CDI recurrence.

Systematic review: prevention of travellers' diarrhoea

BACKGROUND

Renewed interest in the use of antibiotics to prevent travellers' diarrhoea has occurred with the availability of non-absorbed (<0.4%) rifaximin, and with evidence that a subgroup of travellers with diarrhoea have progression of their illnesses to postinfectious irritable bowel syndrome.

AIM

To summarize recently published information and make recommendations on travellers' diarrhoea prevention.

METHODS

PubMed was reviewed on 2 January 2008 for 255 articles on the topic of 'travellers diarrhoea' published beginning with 2000 along with the author's extensive file on prevention of travellers' diarrhoea.

RESULTS

Exercising care in food and beverage selection, while of unproven value, is recommended during travel to high-risk areas of Latin America, Southern Asia or Africa. An algorithm is presented to identify future travellers, for which chemoprophylaxis is appropriate. The preferred drug for prevention of travellers' diarrhoea is rifaximin, with bismuth subsalicylate or a fluoroquinolone also being effective. Vaccines against the principal cause of travellers' diarrhoea, enterotoxigenic Escherichia coli, are being developed.

CONCLUSIONS

Research is needed to determine the relative effectiveness of exercising care on food and beverage selection and chemoprophylaxis in preventing travellers' diarrhoea and postinfectious irritable bowel syndrome during high-risk travel. Enterotoxigenic E. coli vaccines appear to be a promising addition to travel medicine.

Review article: the history of acute infectious diarrhoea management--from poorly focused empiricism to fluid therapy and modern pharmacotherapy

BACKGROUND

Acute diarrhoea management has progressed from largely ineffective measures in the early years to a more effective physiologic approach in recent years.

AIM

To review the history of acute diarrhoea management.

METHODS

Citations in PubMed were reviewed on 'acute diarrhoea treatment' along with an extensive file maintained by the corresponding author.

RESULTS

Freedom from diarrhoea was equated in early military conflicts with bravery and strength where diarrhoea-free soldiers had the 'guts' to fight. Until early 20th century, colonic irrigants, purgatives and emetic drugs were used to help eliminate undesired intestinal contents. Only a few early authorities suggested the need for replacement of fluids and salt, now standard treatment. Drugs aimed at diarrhoea symptom control have been broadly used for more than 100 years. The evolving history of one of those drugs, kaopectate is unappreciated. Once understanding the pathophysiology and infectious aetiology of acute diarrhoea, new oral fluids, pharmacologic agents designed to block specific secretory alterations and anti-infective drugs have been identified.

CONCLUSIONS

Physiologic and antimicrobial approaches to controlling diarrhoea can lead to reduction of stool number and enteric complaints, important in industrialized areas, with the potential for decreasing threat of fatal illness among infants in developing regions.

Rifaximin: in vitro and in vivo antibacterial activity--a review

In vitro inhibitory activity of rifaximin is directed against Gram-positive and Gram-negative, aerobic and anaerobic bacteria. It is effective in the treatment of gastrointestinal infections when given orally because of the high concentration of the drug remaining in the gut lumen. Laboratory investigations have been carried out to assess the in vitro activity of rifaximin on different bacterial strains isolated from both human and domestic animals. The objective of this project is to review the in vitro and in vivo activity of rifaximin against bacterial infection with Gram-negative rods, Gram-positive rods and Gram-positive cocci and their resistance to rifaximin. The available data suggest that rifaximin is active in vitro and in vivo in the treatment of bacterial infection of adults and children.

Influence of rifaximin treatment on the susceptibility of intestinal Gram-negative flora and enterococci

The development of rifaximin- and rifampicin-resistant intestinal coliforms was studied in 27 subjects receiving rifaximin for 3 days by plating stool samples on media containing rifaximin 200 mg/L or rifampicin 64 mg/L before treatment (day 0), after treatment was completed (day 3), and after a further 2 days (day 5). The susceptibility of enterococci grown on day 0 and day 3 was also studied in 71 subjects. Significant increases in antimicrobial-resistant coliform flora were not seen in either the rifaximin-treated or the placebo-treated subjects. Enterococci recovered pre- and post-treatment showed similar susceptibilities. Rifaximin did not select for significant resistance in the Gram-negative and Gram-positive intestinal flora during therapy.

Intestinal immunoglobulin a response to naturally acquired enterotoxigenic Escherichia coli in US travelers to an endemic area of Mexico

BACKGROUND

Simple methods for detecting secretory immunoglobulin A (sIgA) immune responses following natural enteric infection and oral immunization are needed.

METHODS

Fourteen students from the United States acquiring enterotoxigenic Escherichia coli (ETEC) diarrhea in Mexico were studied for fecal immunoglobulin A (IgA) response to their homologous infecting ETEC and to heat-labile (LT) toxin of ETEC using Dot-Blot microfiltration and enzyme-linked immunosorbent assay (ELISA) methods. Paired stool samples were collected on the day of presentation and 5 days later.

RESULTS

Twelve of 14 (86%) patients with ETEC diarrhea (5 heat-stable [ST]/LT positive, 4 LT-only, and 5 ST-only) developed sIgA antibodies directed against their homologous ETEC and 6 (66%) of the 9 patients harboring ST/LT or LT-only strains developed sIgA LT-antibody responses. Single fecal samples from 9 healthy controls were negative for ETEC specific antibodies.

CONCLUSIONS

Patients with diarrhea due to noninvasive ST/LT ETEC and LT ETEC commonly produce a specific sIgA antibody response early in the illness. We feel that the methods employed will be useful to detect antibodies during natural infection by enteric pathogens and following oral enteric vaccine administration.

Rifaximin versus ciprofloxacin for the treatment of traveler's diarrhea: a randomized, double-blind clinical trial

Rifaximin is a poorly absorbed rifamycin derivative under investigation for treatment of infectious diarrhea. Adult students from the United States in Mexico and international tourists in Jamaica were randomized to receive either rifaximin (400 mg twice per day) or ciprofloxacin (500 mg twice per day) for 3 days, following a double-blinded model, from June 1997 to September 1998. A total of 187 subjects with diarrhea were studied. Time from initiation of therapy to passage of last unformed stool was comparable for those receiving rifaximin or ciprofloxacin (median, 25.7 hours versus 25.0 hours, respectively). There was no significant difference in the proportion of subjects in the 2 groups with respect to clinical improvement during the first 24 hours (P=.199), failure to respond to treatment (P=.411), or microbiological cure (P=.222). The incidence of adverse events was low and similar in each group. Rifaximin is a safe and effective alternative to ciprofloxacin in the treatment of traveler's diarrhea.

Increased fecal IgE among infants in a rural community of Egypt: an analysis of associated risk factors

Newborns in rural Bilbeis, Egypt were followed to 1-year of age to document the incidence and risk factors associated with the development of fecal IgE. Factors associated with increased fecal IgE included infants aged 3-6 months (relative risk (RR) = 3.28, 95 per cent confidence intervals (CI) = 1.03-13.60, p < 0.05) and mother being vaccinated antenatally (RR = 2.17, CI - 1.01-4.61, p < 0.05). Decreased fecal IgE was observed with consumption of rice (RR = 0.37, CI = 0.12-0.94, p < 0.05), biscuits (RR = 0.43, CI = 0.15-0.99, p < 0.05), potatoes (RR = 0.39, CI = 0.11-0.98, p < 0.05), and fruits and vegetables (RR = 0.20, CI = 0.02-0.80, p < 0.05). After multivariate adjustment, increased risk was observed with consumption of milk pudding (RR = 7.48, CI = 1.54-36.20, p < 0.05) and wet-nursed infants (RR = 2.77, CI = 1.17-6.54, p < 0.05). Infants who were completely breastfed (RR = 0.13, CI = 0.02-0.68, p < 0.05) and infants' family owning a television set (RR = 0.29, CI = 0.12-0.67, p < 0.05) were less likely to develop fecal IgE. Our findings indicate that prelacteal feeding with certain foods, early supplementation of breastfeeding, and sociodemographic factors are associated with increased fecal IgE.

Sociodemographic, environmental and clinical risk factors for developing persistent diarrhoea among infants in a rural community of Egypt

The study documents the incidence of persistent diarrhoea and its sociodemographic, household, environmental and clinical risk factors. One hundred and fifty-two newborns were followed for the first 12 months of life in Bilbeis, Egypt. The household of each participant was surveyed at baseline and was visited twice a week. The study infants experienced persistent diarrhoea at a rate of 0.51 episode/case per year. Development of persistent diarrhoea was associated with water storage in mud-containers (Odds ratio [OR] = 4.36, confidence interval [CI] 1.4-14.8), pump-water supply (OR = 3.5, CI 1.2-10.2), and absence of a latrine in the household (OR = 2.74, CI 1.01-7.38). Detection of faecal IgE (OR = 3.32, CI 1.0-10.9) and high stool frequency (OR = 2.95, CI 1.1-7.8) appeared as important clinical predictors for the onset of persistent diarrhoea. The incidence of persistent diarrhoea among young infants in Bilbeis, Egypt, was high. Sociodemographic, environmental and clinical parameters were important risk factors for the development of persistent diarrhoea.

Impact of breast-feeding on Giardia lamblia infections in Bilbeis, Egypt

A total of 152 infants were followed from birth to 1 year of age in a rural community of Egypt to document Giardia lamblia infection and to determine the effect of breast-feeding on enteric infections by this protozoan. Asymptomatic Giardia infections persisted as long as 4 months, with a mean duration of excretion of 7.18 weeks. The incidence of asymptomatic infection was 4.5 episodes per child-year. Exclusively breast-fed infants had lower risk for asymptomatic (odds ratio [OR] = 0.66, 95% confidence interval [CI] = 0.45-0.96, P < 0.05) and symptomatic infections (relative risk [RR] = 0.50, 95% CI = 0.27-0.90, P < 0.05). Furthermore, breast-fed infants had fewer clinical manifestations, including mucus in stool (23.8% versus 76.2%, P = 0.08), loss of appetite (17.6% versus 82.3%, P < 0.05), and abdominal tenderness (17% versus 82.9%, P < 0.05) compared with infants who were not exclusively breast-fed. Breast-feeding should be considered as an effective means to prevent Giardia infections and should be encouraged in regions where G. lambia is highly endemic.

EnteroaggregativeEscherichia colias a Major Etiologic Agent in Traveler's Diarrhea in 3 Regions of the World

Enteroaggregative Escherichia coli (EAEC) has been reported to cause traveler's diarrhea and persistent diarrhea in children in developing countries and in immunocompromised patients. To clarify the prevalence of EAEC in traveler's diarrhea, we studied 636 US, Canadian, or European travelers with diarrhea: 218 in Guadalajara, Mexico (June--August 1997 and 1998), 125 in Ocho Rios, Jamaica (September 1997--May 1998), and 293 in Goa, India (January 1997--April 1997 and October 1997--February 1998). Stool samples were tested for conventional enteropathogens. EAEC strains were identified by use of the HEp-2 assay. EAEC was isolated in 26% of cases of traveler's diarrhea (ranging from 19% in Goa to 33% in Guadalajara) and was second only to enterotoxigenic E. coli as the most common enteropathogen in all areas. Identification of EAEC reduced the number of cases for which the pathogen was unknown from 327 (51%) to 237 (37%) and explained 28% of cases with unknown etiology. EAEC was a major cause of traveler's diarrhea in 3 geographically distinct study areas.

In vitro antimicrobial susceptibility testing of bacterial enteropathogens causing traveler's diarrhea in four geographic regions

The emergence of resistant enteropathogens has been reported worldwide. Few data are available on the contemporary in vitro activities of commonly used antimicrobial agents against enteropathogens causing traveler's diarrhea (TD). The susceptibility patterns of antimicrobial agents currently available or under evaluation against pathogens causing TD in four different areas of the world were evaluated. Pathogens were identified in stool samples from U.S., Canadian, or European adults (18 years of age or older) with TD during 1997, visiting India, Mexico, Jamaica, or Kenya. MICs of 11different antimicrobials were determined against 284 bacterial enteropathogens by the agar dilution method. Ciprofloxacin, levofloxacin, ceftriaxone, and azithromycin were highly active in vitro against the enteropathogens, while traditional antimicrobials such as ampicillin, trimethoprim, and trimethoprim/sulfamethoxazole showed high levels and high frequencies of resistance. Rifaximin, a promising and poorly absorbable drug, had an MIC at which 90% of the strains tested were inhibited of 32 microg/ml, 250 times lower than the concentration of this drug in the stools. Amdinocillin, nalidixic acid, and doxycycline showed moderate activity. Fluoroquinolones are still the drugs of choice for TD in most regions of the world, although our study has a limitation due to the lack of Escherichia coli samples from Kenya and possible bias in selection of the patients for evaluation. Azithromycin and rifaximin should be considered as promising new agents. The widespread in vitro resistance of the traditional antimicrobial agents reported since the 1980s and the new finding of resistance to fluoroquinolones in Southeast Asia are the main reasons for monitoring carefully the antimicrobial susceptibility patterns worldwide and for developing and evaluating new antimicrobial agents for the treatment of TD.

Serum antibody response induced in mice after oral administration of three different antigens of enterotoxigenic Escherichia coli in enteric coated microparticles

BACKGROUND

Gastric digestion of these antigens plays an important role, decreasing the ability to deliver antigens to the gut-associated lymphoid tissue. To overcome this obstacle, microencapsulated antigens from enterotoxigenic Escherichia coli (ETEC) were evaluated for oral immunization of mice.

METHODS

Four groups of 10 each received 3 series of 3 doses each of (1) B subunit of cholera toxin (CTB), similar to heat-labile toxin of ETEC, (2) formalin-killed whole cell ETEC H10407 (FK-ETEC), (3) crude preparation of colonization factor antigen I (CFA/I), or (4) placebo. Serum antibody was measured on day 0 and 60 by ELISA.

RESULTS

In group 1 a CTB antibody response was induced in all mice, 3 with 1:105 titer and 7 with 1:106. These antibodies neutralized cholera toxin-induced steriodogenesis of Y-1 adrenal cells. In group 2, 8 mice developed a whole H10407 bacteria antibody titer of 1:100, one 1:200 and one showed no immune response. In the same group, an anti-CFA/I response was observed in 6 mice and anti-LPS in 4 mice as determined by Western blot. All mice in group 3 showed > 1:104 anti-CFA/I antibody titer. Group 4 mice did not develop an immune response to any ETEC antigens.

CONCLUSIONS

Microencapsulation appears to be a suitable approach for oral vaccination against ETEC and Vibrio cholerae.

Empirical antimicrobial therapy for traveler's diarrhea

Over 7 million cases of traveler's diarrhea, defined as the passage of > or = 3 unformed stools in a 24-h period, occur each year among visitors to developing countries. Bacterial enteric pathogens are the most common etiologic agents isolated. Preliminary clinical results for patients with diarrhea predominantly caused by Campylobacter species have shown that azithromycin may be an effective alternative to fluoroquinolones for the treatment of traveler's diarrhea.

Fecal antibodies to Cryptosporidium parvum in healthy volunteers

This study examined the intestinal antibody response in 26 healthy volunteers challenged with Cryptosporidium parvum oocysts. Fecal extracts were assayed for total secretory immunoglobulin A (IgA) and C. parvum-specific IgA reactivity. Specific IgA reactivity was standardized to IgA concentration and expressed as a reactivity index (RI). Anti-C. parvum fecal IgA (fIgA) increased significantly in 17 of 26 (65.4%) following oocyst ingestion. Of those with detectable responses, 59, 76.5, and 94.1% were positive by days 7, 14, and 30, respectively. Volunteers receiving high challenge doses (>1,000 and 300 to 500 oocysts) had higher RIs (RI = 5.57 [P = 0. 027] and RI = 1.68 [P = 0.039], respectively) than those ingesting low doses (30 to 100 oocysts; RI = 0.146). Subjects shedding oocysts and experiencing a diarrheal illness had the highest fIgA reactivity. When evaluated separately, oocyst excretion was associated with an increased fIgA response compared to nonshedders (RI = 1.679 versus 0. 024, respectively; P = 0.003). However, in subjects experiencing diarrhea with or without oocyst shedding, a trend toward a higher RI (P = 0.065) was seen. Extracts positive for fecal IgA were further examined for IgA subclass. The majority of stools contained both IgA1 and IgA2, and the relative proportions did not change following challenge. Also, no C. parvum-specific IgM or IgG was detected in fecal extracts. Thus, fecal IgA to C. parvum antigens was highly associated with infection in subjects who had no evidence of previous exposure and may provide a useful tool in detecting recent infections.

Risk and aetiology of diarrhoea at various tourist destinations

Almost two of three tourists developed traveller's diarrhoea during 2-week stays at high-risk destinations. Large differences in infection rates between hotels were seen. Patients with milder forms of diarrhoea show a similar chronology to those more severely affected. Although enterotoxigenic Escherichia coil was the most frequent cause, viral pathogens were detected more often than in other studies.

Intestinal secretory immunoglobulin A response to enteroaggregative Escherichia coli in travelers with diarrhea

We examined stool samples from travelers for secretory immunoglobulin A (sIgA) to enteroaggregative Escherichia coli (EAEC) during episodes of acute diarrhea. Ten paired samples from 10 patients with diarrhea caused by EAEC were examined for the presence of specific sIgA by dot blot and Western blot immunoassays. Five samples were positive by dot blotting, and two samples were positive by Western blotting.

Characterization of enterotoxigenic Escherichia coli strains in patients with travelers' diarrhea acquired in Guadalajara, Mexico, 1992-1997

The relationship between enterotoxigenic Escherichia coli (ETEC) and travelers' diarrhea was examined in a high-risk area in 1992-1997. Toxin patterns, colonization-factor antigens (CFAs), and in vitro antimicrobial susceptibility were determined. In total, 928 US students with diarrhea acquired in Guadalajara, Mexico, were screened for enteric pathogens. Diagnosis of ETEC infection was done with oligonucleotide probes. ETEC was isolated in 19.9% of the travelers with diarrhea. CFAs were identified in 51% of the ETEC strains. The highest CFA frequency was observed among heat-stable isolates. Ampicillin, furazolidone, and sulfisoxazole resistance of ETEC increased during the study period. ETEC isolation rates and CFA patterns varied little during the 6 years of the study, which has implications for immunoprophylactic strategies. The finding that differences in the results of ribotyping and plasmid analysis change over time suggests that multiple strains of ETEC were responsible for the illness in the region studied.

Interferon-gamma expression in jejunal biopsies in experimental human cryptosporidiosis correlates with prior sensitization and control of oocyst excretion

To investigate the role of interferon (IFN)-gamma in human cryptosporidiosis, jejunal biopsies from experimentally infected volunteers and chronically infected AIDS patients were examined for IFN-gamma expression by in situ hybridization. IFN-gamma expression was compared with oocyst excretion, baseline serum anti-Cryptosporidium antibody, and symptoms. IFN-gamma mRNA was detected in biopsies from 13 of 26 volunteers after experimental infection but not in biopsies taken before C. parvum exposure or in biopsies from patients with AIDS-associated cryptosporidiosis. After challenge, 9 of 10 volunteers with baseline C. parvum antibody produced IFN-gamma, compared with 4 of 16 volunteers without baseline antibody (P<.01). Furthermore, IFN-gamma mRNA was detected in 9 of 13 volunteers who did not excrete oocysts, compared with 4 of 13 with organisms (P<.05). Thus, expression of IFN-gamma in the jejunum was associated with prior sensitization and absence of oocyst shedding. IFN-gamma production may explain the resistance to infection noted in sensitized persons but may not be involved in control of human primary infection.

Etiology of travelers' diarrhea on a Caribbean island

BACKGROUND

Between December 6, 1994 and March 10, 1996, a study of the etiology of diarrhea was carried out among 332 travelers to five all-inclusive hotels in Negril, Jamaica.

METHODS

Stool specimens were collected and sent to Montego Bay for laboratory analysis. Escherichia coli strains isolated at the Jamaican laboratory were sent to Houston for toxin testing.

RESULTS

A recognized enteropathogen was found in 118 of the 332 (35.5%) cases. Enterotoxigenic E. coli (ETEC) were the most commonly identified pathogen (87/332; 26.2%) followed by Salmonella (4.2%) and Shigella (4.2%). Clustering of etiologically defined cases was studied at each hotel. A cluster was defined as 2 or more cases with the same pathogen identified in the same hotel within 7 days. In the 3 hotels with the highest number of cases of diarrhea, enteropathogens were part of a cluster in 65 of 99 cases (65.7%) of diarrhea of which an etiologic agent was identified. In the other 2 hotels, only 4 of 20 cases (20%) occurred in clusters.

CONCLUSIONS

A total of 25 clusters of travelers' diarrhea cases was detected at the five hotels during the study period. Seventeen of 25 (68%) ETEC isolations occurred as part of a clustering of diarrhea cases. The largest outbreak of pathogen-identified diarrhea consisted of 7 cases of ETEC producing both heat-stable and heat-labile enterotoxins. In the Jamaican hotels with all inclusive meal packages most diarrhea cases occurred as small clusters, presumably as the result of foodborne outbreaks.

Improved detection of enterotoxigenic Escherichia coli among patients with travelers' diarrhea, by use of the polymerase chain reaction technique

This study sought to determine whether a specific polymerase chain reaction (PCR) for enterotoxigenic Escherichia coli (ETEC) toxins after chaotropic extraction of DNA from stool would increase the detection of ETEC over that of conventional oligonucleotide probe hybridization of 5 E. coli colonies per stool sample (a standard method). By DNA hybridization, 29 (21%) of 140 patients were positive for ETEC, and 59 (42%) of 140 were positive for ETEC when PCR was used. Sensitivity of the PCR assay was confirmed through spiked stool experiments to be approximately 100-1000 ETEC colonies per sample. Specificity of the assay was determined by showing an absence of ETEC by the PCR technique in a subgroup of 48 subjects and by confirming the presence of ETEC DNA of positive samples by dot blot procedure. PCR technique detected significantly more ETEC infections in these subjects than did the hybridization method (P<.0001).

Virulence of three distinct Cryptosporidium parvum isolates for healthy adults

The infectivity of three Cryptosporidium parvum isolates (Iowa [calf], UCP [calf], and TAMU [horse]) of the C genotype was investigated in healthy adults. After exposure, volunteers recorded the number and form of stools passed and symptoms experienced. Oocyst excretion was assessed by immunofluorescence. The ID50 differed among isolates: Iowa, 87 (SE, 19; 95% confidence interval [CI], 48.67-126); UCP, 1042 (SE, 1000; 95% CI, 0-3004); and TAMU, 9 oocysts (SE, 2.34; 95% CI, 4.46-13.65); TAMU versus Iowa, P=.002 or UCP, P=.019. Isolates also differed significantly (P=.045) in attack rate between TAMU (86%) and Iowa (52%) or UCP (59%). A trend toward a longer duration of diarrhea was seen for the TAMU (94.5 h) versus UCP (81.6 h) and Iowa (64.2 h) isolates. C. parvum isolates of the C genotype differ in their infectivity for humans.

A multicenter randomized controlled trial of a liquid loperamide product versus placebo in the treatment of acute diarrhea in children

This randomized, double-blind, placebo-controlled trial of 48 hours' duration conducted in 13 primary care ambulatory practices in the United States and Mexico was used to compare the efficacy and safety of loperamide with placebo for the treatment of acute diarrhea in children aged 2 through 11 years. Two hundred fifty-eight children with acute nonspecific diarrhea were enrolled. Children were randomly assigned to treatment with loperamide HCl 0.5 mg/5 mL (n = 130) or placebo (n = 128). The first dose of loperamide consisted of either 1.0 mg (children 2 through 5 years of age) or 2.0 mg (children 6 through 11 years of age) of study medication under the observation of study personnel. This was followed by 1 mg after each unformed stool, with a total daily dose of up to 3.0 mg in the children 2-5 years of age, 4.0 mg in the children 6-8 years of age, and 6.0 mg in the children 9-11 years of age. The primary outcome measures were time to last unformed stool, time to first unformed stool, number of unformed stools during six consecutive 8-hour periods, and overall rating of efficacy/acceptability. Secondary outcomes included abdominal pain/cramping, vomiting, and fever. Children who received loperamide had significantly shorter time to last unformed stool (p = 0.0017) and fewer numbers of unformed stools (p = 0.0237) than children who received placebo. The end-of-study overall efficacy/acceptability rating of loperamide was significantly better than for placebo (p = 0.0107). All other clinically important outcome measures related to diarrhea relief favored loperamide. There was no significant difference in the incidence of drug-related adverse events between treatment groups, although total adverse events were reported more frequently (p = 0.048) by the loperamide group (15%) compared with the placebo group (7%). In conclusion, this controlled study provides data demonstrating that at recommend doses, loperamide is well tolerated and significantly shortens the duration and severity of symptoms of acute nonspecific diarrhea in children 2 through 11 years of age.

Enteroaggregative Escherichia coli as a cause of traveler's diarrhea: clinical response to ciprofloxacin

The purpose of this study was to determine the role of enteroaggregative Escherichia coli (EAEC) in the development of traveler's diarrhea and the clinical response of patients with EAEC diarrhea following treatment with ciprofloxacin. Sixty-four travelers with diarrhea and no other recognized enteropathogen were enrolled in treatment studies in Jamaica and Mexico from July 1997 to July 1998. EAEC was isolated from 29 travelers (45.3%). There was a significant reduction in the duration of posttreatment diarrhea in the 16 patients treated with ciprofloxacin, as compared with that in the 13 patients who received placebo (mean of 35.3 versus 55.5 hours; P = .049). There was a nonsignificant reduction in the mean number of unformed stools passed during the 72 hours after enrollment in the ciprofloxacin-treated group (5.6), as compared with that in the placebo group (7.5) (P = .128). This study provides additional evidence that EAEC should be considered as a cause of antibiotic-responsive traveler's diarrhea.

Oral rehydration therapy plus loperamide versus loperamide alone in the treatment of traveler's diarrhea

Eighty United States students in Mexico received either loperamide (an initial dose of 4 mg, followed by 2 mg after passage of each unformed stool, up to 8 mg/d; 40 patients) or loperamide (at the same dosage schedule) plus an oral rehydration therapy (ORT) preparation (500 mL initially, followed by 250 mL after each subsequently passed unformed stool, up to 1,000 mL per 24 hours; 40 patients). The ORT preparation was a modification of the World Health Organization-recommended solution, adjusted to a sodium concentration of 60 mEq/L. All treatments were given for 48 hours. The study demonstrated equivalent clinical responses with regard to diminishment of diarrhea or subjective findings such as abdominal pain/cramps, headache, dry mouth, dizziness, or thirst. Stool number (by form) and specific gravity of urine postenrollment were similar in the groups. Administration of loperamide plus ORT for the management of traveler's diarrhea, in cases in which subjects were encouraged to drink ad libitum, offered no benefit over administration of loperamide alone.

Epidemiology, etiology, and impact of traveler's diarrhea in Jamaica

CONTEXT

Traveler's diarrhea (TD) can incapacitate travelers. Characteristics of TD could be helpful in identifying individuals who might benefit from a vaccine against TD.

OBJECTIVE

To determine epidemiology, etiology, and impact of TD in Jamaica. Design Two-armed, cross-sectional survey conducted between March 1996 and May 1997.

SETTING

Sangster International Airport and 10 hotels in Montego Bay area, Jamaica.

SUBJECTS

To investigate epidemiology and impact, 30369 short-term visitors completed a questionnaire just before boarding their homebound aircrafts. To investigate etiology, 322 patients (hotel guests) with TD provided stool samples.

MAIN OUTCOME MEASURES

Attack and incidence rates of reported diarrhea and of classically defined TD (> or =3 unformed stool samples in 24 hours and > or =1 accompanying symptom), incapacity, risk factors, and etiology.

RESULTS

The attack rate for diarrhea was 23.6% overall, with 11.7% having classically defined TD. For a mean duration of stay of 4 to 7 days, the incidence rate was 20.9% (all TD) and 10.0% (classic TD). Among airport respondents, the incapacity lasted a mean of 11.6 hours. Less than 3% of all travelers avoided potentially high-risk food and beverages. The most frequently detected pathogens were enterotoxigenic Escherichia coli, Rotavirus, and Salmonella species.

CONCLUSIONS

A realistic plan for reducing TD is needed. Preventive measures such as the improvement of hygienic conditions at the destination, and/or the development of vaccines against the most frequent pathogens associated with TD may contribute toward achieving this goal.

HIV-1 seroprevalence in Zambian patients with acute diarrhea: a community-based study

The seroprevalence of HIV-1 in sub-Saharan African patients with diarrhea in the community remains largely unknown. We present the findings of a 2-month study that we undertook to ascertain the seroprevalence of HIV-1 in Zambian patients presenting with acute diarrhea in a community-based health center. A total of 256 patients with diarrhea and 140 apparently healthy controls was seen. Of the patients with diarrhea, 161 were < 16 years old and 95 were adults. Most children with diarrhea were < 6 years old (147 of 161; 91%). Overall, 81 of 256 (32%) patients with diarrhea were HIV-1-seropositive. When results from children < 18 months old and possibly having maternal anti-HIV-1 antibodies were excluded, 64 of 172 (37%) patients with diarrhea were HIV-seropositive. Rates of HIV-1 seropositivity for patients with diarrhea were significantly higher than were rates for diarrhea-free controls (p < .001 for both the total population; odds ratio [OR], 95% confidence interval [CI], 1.42 < 2.48 < 4.35) and population > 18 months old (OR, 95% CI, 1.54 < 2.90 < 5.49). Among children between 18 months and 5 years old, 14 of 63 (22%) were HIV-1-seropositive compared with 8 of 62 (13%) without diarrhea (p > .05, not significant). Moreover, 49 of 95 (52%) adults with acute diarrhea were HIV-1-seropositive compared with 10 of 44 (23%) healthy adult controls (p < .003; OR, 95% CI, 1.51 < 3.62 < 8.87). No significant differences were found in HIV-1 seroprevalence rates between males and females in all age groups. These data show a close association between acute diarrhea and HIV seropositivity in Zambian adults in the community.

Rifaximin: a nonabsorbed antimicrobial in the therapy of travelers' diarrhea

BACKGROUND/AIMS

Bacterial enteropathogens, the major cause of travelers' diarrhea, are customarily treated with antibacterial drugs. Rifaximin, a nonabsorbed antimicrobial was examined as treatment for travelers' diarrhea.

METHODS

A randomized, prospective, double-blind clinical trial was carried out in 72 US adults in Mexico. Patients with acute diarrhea received one of three doses of rifaximin (200, 400 and 600 mg t.i.d.) or trimethoprim/sulfamethoxazole (TMP/SMX, 160 mg/800 mg b.i.d.) for 5 days. Results were compared with data from 2 placebo-treated historical control populations.

RESULTS

The shortest duration of treated diarrhea was seen in the group receiving 200 mg rifaximin t. i.d (NS). Clinical failure to respond to treatment occurred in 6 of 55 (11%) rifaximin-treated subjects versus 5 of 17 (29%) of TMP/SMX-treated subjects (NS). Sixteen of twenty (80%) of the enteropathogens isolated from the rifaximin-treated subjects and 7 of 7 (100%) from the TMP/SMX group were eradicated by treatment (NS). Sixteen of twenty-four (67%) enteropathogens identified were susceptible to TMP and all 24 were inhibited by</=50 microgram/ml of rifaximin. Rifaximin reduced the number of unformed stools passed during the first 24 h of treatment when compared with 2 control placebo groups (3.3 versus 5.1; p = 0.008 and 0.0001) and led to a reduced duration of post-enrollment diarrhea (mean values of 43.1 versus 68.1 and 81.9 h; p = 0.001).

CONCLUSIONS

Rifaximin shortened the duration of travelers' diarrhea compared with TMP/SMX and 2 earlier studied placebo-treated groups. A poorly absorbed drug if effective in treating bacterial diarrhea has pharmacologic and safety advantages over the existing drugs.

The antibody response to 27-, 17-, and 15-kDa Cryptosporidium antigens following experimental infection in humans

Previous studies have suggested that persons infected with Cryptosporidium parvum develop antibody responses to 27-, 17-, and 15-kDa C. parvum antigens. Studies of volunteers infected with Cryptosporidium species provided an opportunity to evaluate the relationship between antibody reactivity to these antigens and infection outcome. As monitored by immunoblot, increases in specific antibody reactivity were more prevalent among volunteers who developed signs and symptoms of cryptosporidiosis (n = 11) than among asymptomatic infected (n = 7; P = .05) or oocyst-negative volunteers (n = 11; P = .02). Volunteers with preexisting IgG antibody to the 27-kDa antigen excreted fewer oocysts than volunteers without this antibody (P = .003). IgG reactivity to the 17-kDa antigens and IgM reactivity to the 27-kDa antigens were higher at day 0 for asymptomatic infected persons than for those who developed symptoms (P = .03 and P = .04, respectively). These results suggest that characteristic antibody responses develop following C. parvum infection and that persons with preexisting antibodies may be less likely to develop illness.