Seroconversion to Entamoeba histolytica among short-term travelers to Mexico.

Paired serum samples were evaluated for the presence of antibodies to Entamoeba histolytica in 326 healthy college students from the United States who lived in Guadalajara, Mexico, for an average of four weeks. One hundred eighty of these students had an enteric illness develop, but no stool test results were positive for ameba. An indirect hemagglutination assay was the serologic method used, and no seroconversion was demonstrates. This finding confirms the belief that amebiasis is a rare cause of diarrhea among short-term travelers to Mexico.

Contaminated stethoscopes revisited.

BACKGROUND: Because of their universal use by medical professionals, stethoscopes can be a source of nosocomial infections. OBJECTIVE: To determine the frequency of contamination of stethoscopes with bacteria and fungi. METHODS: Cultures were obtained from 200 stethoscopes from four area hospitals and outpatient clinics in Houston, Tex. The frequency of stethoscope contamination in different groups of hospital personnel and medical settings was determined. We also measured the frequency of antimicrobial resistance of the staphylococcal strains that were isolated. RESULTS: One hundred fifty-nine (80%) of the 200 stethoscopes surveyed were contaminated with microorganisms. The majority of organisms that were isolated were gram-positive bacteria, primarily Staphylococcus species. Fifty-eight percent of the Staphylococcus species that were isolated, including four (17%) of 24 Staphylococcus aureus isolates, were resistant to methicillin. Physicians' stethoscopes were contaminated more often than those of other medical personnel groups (P = .02). Stethoscopes used only in designated areas were contaminated less frequently than stethoscopes belonging to individual medical personnel (P = .01). Although stethoscopes were contaminated in all areas, stethoscopes from the pediatric medical setting were contaminated less frequently than those from other hospital areas (P = .009). CONCLUSIONS: Stethoscope use may be important in the spread of infectious agents, including antimicrobial-resistant strains, and strategies to reduce the contamination of stethoscopes should be developed. We recommend disinfection of stethoscopes or regular use of disposable stethoscope covers.

Panophthalmitis due to Bacillus cereus.

A rapidly progressing panophthalmitis due to Bacillus cereus developed in three patients. Infection was associated with intravenous drug abuse in two patients and was traced to contaminated injection paraphernalia in one. In the third patient, infection was associated with a foreign-body injury to the eye. Anterior chamber aspiration revealed the organism on Gram's stain in one case and isolation of the bacteria in all three. Despite intravenous and intraocular antibiotic therapy, the infection progressed rapidly and resulted in enucleation in all cases. Bacillus cereus isolates were sensitive to clindamycin hydrochloride hydrate and aminoglycosides but resistant to penicillins and cephalosporins.

A cost-effectiveness comparison of the use of antimicrobial agents for treatment or prophylaxis of travelers' diarrhea.

We conducted a decision analysis to compare the cost-effectiveness of antimicrobial agents used for treatment with their use for prophylaxis of travelers' diarrhea. Estimates of the likelihood and the cost of various outcomes were obtained from a panel of experts using the Delphi group opinion technique. Treatment with sulfamethoxazole-trimethoprim for three days was compared with daily prophylaxis with sulfamethoxazole-trimethoprim or doxycycline. The cost-effectiveness of prophylaxis with either agent (75% to 83%) was greater than that of treatment (38%). Treatment would become more cost-effective than prophylaxis when the cumulative risk of acquiring travelers' diarrhea was less than 0.05 episodes per person per week or if the effectiveness of prophylaxis fell below 35% for doxycycline and 46% for sulfamethoxazole-trimethoprim. The most important contributor to the mean cost of travelers' diarrhea in this analysis was the cost associated with a day of incapacitation due to illness. On the basis of the results of this decision analysis, we conclude that prophylaxis of travelers' diarrhea is an option that should be considered for individual situations and recommend further studies of its cost-effectiveness.

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.

Salicylate absorption from a bismuth subsalicylate preparation.

The active ingredient in Pepto-Bismol (PB) (Norwich-Eaton), a common antidiarrheal, is bismuth subsalicylate. The absorption of salicylate after oral PB was studied in six fasted men. Plasma concentrations of total salicylate and the urinary excretion profile of salicylate were determined as a function of time and dose. After 60 ml PB, 500.1 +/- 33.6 mg (mean +/- SD) salicylate were recovered in urine, representing 95.0 +/- 6.4% of salicylic acid equivalents in 60 ml of the formulation. Peak plasma salicylate levels were reached 0.5 to 3 hr after ingestion and averaged 40.1 +/- 17.3 micrograms/ml. Absorption of salicylate was also essentially complete after 15- and 30-ml doses of the antidiarrheal preparation, and a linear relationship between dose and recovery of salicylate in the urine was found. Salicylate kinetics was nonlinear after a multiple-dose regimen of 60 ml every 6 hr for five doses.

Safety and efficacy of loperamide.

Loperamide is a safe and effective antidiarrheal for the treatment of acute diarrhea. Efficacy data suggest that loperamide is more effective than the prescription drug diphenoxylate and an over-the-counter bismuth subsalicylate preparation. Loperamide is a safe drug, with few adverse reactions reported worldwide. It also lacks significant abuse potential. Loperamide may prove to be the antidiarrheal agent of choice when compared with currently available nonprescription treatments for acute diarrhea.

Acute diarrhea in developed countries. A rationale for self-treatment.

Acute diarrhea is a common, nonlethal condition that causes frequent inconvenience and economic loss. People rarely consult physicians for this problem. Epidemiologic studies among adults, hospitalized adults, children attending day care centers, homosexual men, and travelers indicate a wide spectrum of etiologic agents. The clinical presentation of acute diarrhea may lead clinicians to consider certain causative agents, but it is not diagnostic of any specific cause. Clinical laboratory studies can detect or isolate pathogens in only a minority of cases. By the time this information is available, patients have usually recovered. For these reasons, early self-treatment aimed at reducing symptoms of acute diarrhea is recommended.

Current problems in antimicrobial therapy for bacterial enteric infection.

Trimethoprim/sulfamethoxazole is currently considered the treatment of choice for shigellosis and severe travelers' diarrhea. The problem with this combination regimen is inactivity against Campylobacter jejuni strains and other bacterial enteropathogens showing in vitro resistance to the drug. Resistance to trimethoprim/sulfamethoxazole among enteric pathogens has occurred frequently in certain areas of the world. A study of the in vitro susceptibility of enteric bacterial pathogens isolated from multiple countries was recently performed. The minimal inhibitory concentration of ciprofloxacin required to inhibit 90 percent of the 210 bacterial enteropathogens ranged from 0.25 micrograms/ml for C. jejuni to 0.016 micrograms/ml for enterotoxigenic Escherichia coli, Salmonella, and Shigella. In a clinical trial carried out in a United States student population that acquired diarrhea while in Mexico, it was shown that ciprofloxacin was as effective as trimethoprim/sulfamethoxazole and both were significantly (p less than 0.001) more effective than placebo. The average duration of diarrhea was 29 or 20 hours after initiation of treatment with ciprofloxacin or trimethoprim/sulfamethoxazole, respectively, compared with 81 hours in the placebo group. The antimicrobial agents were more efficacious than placebo in treating diarrhea caused by enterotoxigenic E. coli, invasive enteropathogens, and unknown pathogens. Ciprofloxacin and the quinolone derivatives are uniquely suited to the therapy of acute bacterial diarrhea in areas where C. jejuni is commonly found and where trimethoprim/sulfamethoxazole-resistant strains regularly occur.

A randomized, open-label comparison of nonprescription loperamide and attapulgite in the symptomatic treatment of acute diarrhea.

The efficacy of nonprescription doses of loperamide hydrochloride (Imodium A-D) was compared with nonfibrous activated attapulgite (Diasorb) in a randomized, parallel, open-label study of adult patients with acute diarrhea. The results of the study showed loperamide to be more effective than attapulgite in the control of diarrhea. Loperamide significantly reduced stool frequency compared with attapulgite, particularly within the first 12-hour period following the start of therapy, and significantly shortened the mean time to last unformed stool (loperamide, 14.2 hours, versus attapulgite, 19.5 hours). Subjective evaluations of severity of enteric symptoms, overall relief following treatment, and overall relief after 48 hours of treatment were equivalent for both drugs. Both treatments were well tolerated, and there was no difference between treatments with respect to the proportion of patients reporting adverse experiences.

Comparative efficacy of loperamide hydrochloride and bismuth subsalicylate in the management of acute diarrhea.

An open-label, parallel comparison of loperamide hydrochloride (Imodium A-D) and bismuth subsalicylate (Pepto-Bismol) was conducted using nonprescription dosages in adult students with acute diarrhea (three or more unformed stools in the preceding 24 hours plus at least one additional symptom of enteric infection). For the two-day study period, the daily dosage was limited to 8 mg (40 ml) for loperamide-treated subjects and to 4.9 g for bismuth subsalicylate-treated subjects. At these dosages, loperamide significantly reduced the average number of unformed bowel movements relative to bismuth subsalicylate. Following the initial dose of treatment, control of diarrhea was maintained significantly longer with loperamide than with bismuth subsalicylate. Time to last unformed stool was significantly shorter with loperamide than with bismuth subsalicylate. In providing overall subjective relief, subjects rated loperamide significantly better than bismuth subsalicylate at the end of the 24 hours. Both treatments were well tolerated, and none of the minor adverse effects reported resulted in discontinuation of therapy. It was concluded that loperamide is effective at a daily dosage limit of 8 mg (40 ml) for the treatment of acute nonspecific diarrhea and provides faster, more effective relief than bismuth subsalicylate.

Nosocomial outbreak caused by a multiresistant clone of Acinetobacter baumannii: results of the case-control and molecular epidemiologic investigations.

OBJECTIVE: To describe a nosocomial outbreak caused by multiresistant Acinetobacter baumannii. DESIGN: Descriptive and case-control study. Antibiotic susceptibilities and pulsed-field gel electrophoresis (PFGE) of genomic DNA digested with SfiI and also with ApaI were used as markers of strain identity. SETTING: A large medical school-affiliated hospital in the city of Houston, Texas. RESULTS: During a 10-week period, A baumannii was isolated from 25 patients admitted to the intensive care unit (ICU). The attack rate was 14.3 per 100 ICU admissions. Case patients were intubated more frequently and for longer periods, and had longer ICU and hospital stays (P < 0.05 for each of these characteristics). Multivariate logistic regression analysis identified the length of ICU stay and the use of third-generation cephalosporins as associated with the acquisition of A baumannii. Patients infected with A baumannii had a higher mortality rate than colonized patients and control patients (P < 0.01). Sixteen isolates recovered from these 25 patients were susceptible only to imipenem/cilastatin, and PFGE confirmed that a single clone was the cause of this outbreak. Nine isolates of A baumannii from patients infected or colonized in two other hospitals in Houston during the same period, differed from the outbreak isolates by their susceptibility to ciprofloxacin. However, PFGE results were identical, indicating unsuscepted genetic relatedness among isolates from three different hospitals. CONCLUSIONS: A baumannii is an important nosocomial opportunistic pathogen and can adversely affect the outcome of ICU patients who acquire this organism. This outbreak was caused by a single clone that was isolated concurrently from three hospitals.

Travelers' diarrhea. Epidemiology, prevention, and self-treatment.

Risk factors for travelers' diarrhea include adventurous behavior, consumption of unclean water or food, and special hosts like those taking long acting H2 blockers. Approaches to prevention include education about risk factors, which often fails to lead to modification of risky behavior, and chemoprophylaxis with bismuth subsalicylate-containing compounds or antimicrobial agents. Chemoprophylaxis is generally discouraged except in special circumstances and in high-risk hosts. Self-treatment of travelers' diarrhea is successful in limiting the course of diarrhea and minimizing losses of vacation and business time. Current therapeutic options, in order of increasing effectiveness, include attapulgite, BSS-containing compounds, loperamide, antimicrobial agents such as the fluoroquinolones, and the combination of loperamide and an antimicrobial agent. Under study are a nonabsorbed antimicrobial agent, rifaximin, and a novel calmodulin inhibitor, zaldaride. Development and evaluation of vaccines against enterotoxigenic Escherichia coli and Shigella are proceeding apace but are not yet available for routine use.

Occult blood versus fecal leukocytes in the diagnosis of bacterial diarrhea: a study of U.S. travelers to Mexico and Mexican children.

A study was done to test the effectiveness of fecal occult blood as a screening test for invasive bacterial pathogens and as a substitute for the fecal leukocyte examination in adult and pediatric cases of acute diarrhea. United States citizens studying in Mexico and Mexican children, both with acute diarrhea had their stools cultured, examined for fecal leukocytes, and tested for occult blood. Using culture results as the criterion standard for detection of bacterial agents, and fecal leukocytes for diarrhea associated with diffuse colonic inflammation, occult blood was tested for its sensitivity, specificity, and predictive value using 2 x 2 tables. Analysis of the data found that occult blood negative samples were reliable indicators of a lack of invasive bacteria in both adult and pediatric patients (negative predictive values of 87% and 96%, respectively). Positive results for either test were not reliably predictive as indicators of invasive bacteria among adults. A positive occult blood test result was significantly more sensitive than a positive fecal leukocyte test result (79% versus 42%) in detecting invasive bacteria in the pediatric patients; however, the positive predictive value was only 24%. The fecal occult blood test is an uncomplicated, low-cost test that was reliable when giving a negative result in detecting a lack of invasive bacteria in adult and pediatric patients with diarrhea. In children, a positive result on a fecal occult blood test is sensitive but not specific in detecting invasive bacterial enteropathogens. These data also indicate that a commercially available test for occult blood represents a suitable alternative to microscopic examination of fecal samples for leukocytes obtained from patients with acute diarrhea.

Comparative bioavailability of intravenous and oral chloramphenicol in adults.

The comparative bioavailability of chloramphenicol from intravenous succinate, oral palmitate, and oral base preparations was studied in a crossover manner in 12 adult patients. Chloramphenicol was administered at a dose of 1 Gm every 6 hours, and blood samples were collected at steady state. For the succinate study, total urine output was also collected. The bioavailability of active chloramphenicol from the succinate preparation averaged 85.8 +/- 42.3 and 78.8 +/- 50.1 per cent of the free base and palmitate forms, respectively. This lower availability appeared to be due to variable excretion of unchanged succinate in the urine, averaging 27 +/- 11 per cent of the dose. Regardless of dosage form or route of administration, plasma chloramphenicol concentrations remained in the therapeutic range (5 to 25 mg/liter) for the entire dosage interval, implying that no change needs to be made when changing dosage form or route of administration. The interpatient variability, however, supports the need for monitoring of plasma chloramphenicol concentrations, especially in newborn infants, persons with liver disease, or those receiving other medications that alter chloramphenicol metabolism.

Prevention and empiric treatment of traveler's diarrhea.

Diarrheal illness has plagued travelers for centuries, and to this day it remains the most common medical problem affecting travelers from industrialized nations to areas of the world where substandard hygiene conditions and sanitation prevail. This article discusses the cause of diarrheal illness in travelers, as well as epidemiology, prevention, treatment, and a general approach to self-treatment.

Travelers' diarrhea. Prevention and treatment.

Travelers' diarrhea affects almost half of all travelers from developed to developing nations. Its occurrence frequently alters planned activities. Enterotoxigenic Escherichia coli and other bacterial pathogens endemic to the area visited account for the majority of pathogens isolated. Newer research technologies are assisting in defining virulence properties and epidemiologic characteristics. Prudence exercised during travel remains the preferred mode of prevention, reserving antimicrobial prophylaxis for specific situations. Oral rehydration and early pharmacologic intervention with antimicrobial and antimotility agents significantly decrease length of illness when diarrhea occurs.

Comparative studies of antibiotic therapy after penetrating abdominal trauma.

Two prospective, randomized trials of the efficacy of antibiotic regimens after penetrating abdominal trauma demonstrated that a combination of clindamycin and tobramycin was superior to cefamandole or cefoxitin in preventing postinjury wound infection but that no difference could be demonstrated between combination therapy (clindamycin plus tobramycin) and moxalactam. Infection was more likely to occur after a gunshot wound or with a high injury severity score and occurred after the 10th postinjury day only in those patients who received cefamandole or cefoxitin. There was a higher incidence of culture of B. fragilis in the latter groups as well as infections due to resistant organisms. Short-term antibiotic therapy for 72 hours with either tobramycin plus clindamycin or moxalactam appears adequate for the majority of patients after gunshot or knife wounds. The costs of these regimens to the patient were similar in our hospital. The most important single factor, however, in maintaining low infection rates after penetrating injury to the abdominal cavity is appropriate and timely surgical management.

Systemic absorption of bacitracin after peritoneal lavage.

Nine patients underwent intraoperative peritoneal lavage with a solution containing 50,000 units of bacitracin in 200 ml of 0.9 per cent sodium chloride. The solution was removed by suction at 2 or 5 minutes, and venous blood samples were obtained at 15 minute intervals for 2 hours after lavage. Concentrations of bacitracin in serum were determined by agar diffusion assay. In the majority of patients, peak concentrations of bacitracin in serum occurred by 15 minutes post lavage. The mean peak serum concentration was 3.8 units/ml, which exceeds peak concentrations after intramuscular injection of 50,000 units. Due to potential nephrotoxicity, bacitracin should be used cautiously in peritoneal lavage solutions and should be abandoned in patients who have renal impairment in whom prolonged elevated serum concentrations could develop.

Emporiatric enteritis: lessons learned from U.S. students in Mexico.

In the studies reported, evidence has been presented that U.S. students traveling to Mexico represent a model for the study of travelers' diarrhea. The incidence of illness acquisition approximates that published in other studies of travelers. Natural immunity was shown to develop as students remained in Mexico presumably through repeated exposure to prevalent agents, particularly ETEC. ETEC, shigella strains and no detectable agent represented the largest groups when etiologic assessment was made. Food probably served as the important source of diarrhea particularly that due to ETEC and shigella strains. The level of bacteria isolated from food suggested that organism replication occurred due to improper temperature storage rather than to heavy initial contamination. The location of food consumption was related to degree of risk: self preparation was the safest, eating in Mexican homes the least safe and consumption of food in public restaurants was intermediate in risk. Water probably played a role in the transmission of viral infection. The risk of water contamination appeared to be highest during the rainy seasons. Finally, the antimicrobial agents TMP/SMX and TMP alone were shown to effectively prevent and treat this form of travelers' diarrhea.