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Biomedical subjects

R B Sack

Publications and source records attributed to R B Sack.

At least 109 records · Page 6Linked to original sources
PubMed1992

Virulence properties of Enterobacteriaceae isolated from the small intestine of children with diarrhea.

Enterobacteriaceae isolated from the duodena of Peruvian children with persistent diarrhea (PD) have been examined for virulence factors and compared with Enterobacteriaceae isolated from children with acute diarrhea, those convalescent from PD and diarrhea-free controls. Escherichia coli were isolated from 42 of 186 (23%) of the aspirates. All 11 children with PD in whom multiple E. coli colonies were examined were colonized by a single serotype. DNA probes identified enterotoxigenic E. coli in 2 of 89 (2.2%) PD aspirates and 2 of 38 (5.3%) acute diarrhea aspirates and enteroaggregative E. coli in one PD and one control aspirate. Strains positive with the enteropathogenic E. coli adherence factor probe were identified from 2 of 89 (2.2%) patients with PD and 1 of 34 (2.9%) controls. A subset of 12 E. coli strains failed to show adhesion to human duodenal enterocytes although 5 of 9 showed sparse but polar attachment to ileal cells from a child with short bowel syndrome and PD. Three of 10 Enterobacteriaceae (two E. coli, one Klebsiella species) caused diarrhea in the reversible ileal tie adult rabbit model. Colonization with virulent Enterobactericeae did not explain the majority of episodes of PD. Examination of these duodenal bacteria in the rabbit model revealed some that caused diarrhea but were not recognized pathogens.

Bacterial Toxins↗
PubMed1992

Enterotoxigenic Bacteroides fragilis: epidemiologic studies of its role as a human diarrhoeal pathogen.

Strains of Bacteroides fragilis which produce enterotoxin(s) (ETBF) have been associated with diarrhoeal diseases in young domestic animals and have also been isolated from humans with diarrhoea. We have determined epidemiologically that ETBF are significantly associated with diarrhoea in humans. We studied Apaches, primarily children, with diarrhoea attending an outpatient facility in Whiteriver, Arizona, from July 1986 through July, 1988. Stool cultures for isolation of ETBF and other diarrhoeal pathogens were taken from these persons as well as from age and time-matched control persons who did not have diarrhoea. ETBF were isolated significantly more often from persons with diarrhoea (12%) than from controls (6%), p = 0.03. Isolation was highest (20-24% of stool cultures positive) during the second and third years of life. The diarrhoeal syndrome associated with ETBF was non-specific, and most characteristic of a secretory, rather than inflammatory, type of diarrhoea. ETBF are significantly associated with acute diarrhoea in Apache children, and may be an important newly described cause of diarrhoea in humans.

Acute Disease↗
PubMed1991

Methodological issues in diarrhoeal diseases epidemiology: definition of diarrhoeal episodes.

A review of the diarrhoeal disease literature reveals considerable variability in the definition of diarrhoeal episodes. The use of various definitions of diarrhoea and episodes leads to misclassification, affects the estimates of the disease burden in communities and reduces comparability of the findings from different studies. This study is an attempt to validate the definition of diarrhoeal episodes using prospectively collected community-based surveillance data. In comparative validation analyses, three or more loose stools or any number of loose stools containing blood in a 24-hour period seemed to be the best definition of diarrhoea. Three intervening diarrhoea-free days seemed to be the optimum to define a new episode. The implications of using differing definitions and the importance of using a validated definition are discussed.

Bangladesh↗
PubMed1991

A field study of the safety and efficacy of two candidate rotavirus vaccines in a Native American population.

A double-blind, randomized, placebo-controlled trial was conducted to evaluate the safety and efficacy of a rhesus rotavirus vaccine and RIT 4237, a bovine rotavirus vaccine, in a Navajo population. Infants aged 2-5 months were randomized to receive one dose of either 10(4) pfu of the rhesus rotavirus vaccine or 10(8) pfu of the RIT 4237 vaccine or placebo. Eleven (10.2%) of 108 infants in the rhesus vaccine group, 11 (10.4%) of 106 in the RIT 4237 group, and 9 (8.4%) of 107 in the placebo group experienced rotavirus diarrhea during the follow-up period of 17 months. Thus, in this population, neither vaccine was efficacious in preventing rotavirus diarrhea.

Diarrhea, Infantile↗
PubMed1991

Measles-associated diarrhea in hospitalized children in Lima, Peru: pathogenic agents and impact on growth.

Because the causes of measles-associated diarrhea are not well known, 0- to 5-year-old children presenting to the hospital with measles-associated diarrhea (cases, n = 77) or acute diarrhea only (controls, n = 77) were compared. Growth and diarrheal morbidity were evaluated for 1 month after acute illness. Campylobacter jejuni was more frequently isolated from cases (31%) than controls (16%; P = .03). Rotavirus was absent in all cases versus 28% of controls (P less than .001). Incidence density for new episodes of diarrhea was significantly greater in cases (6.5 vs. 4.1; odds ratio, 1.6; confidence intervals, 1.09-2.34; P = .01), as was duration of episodes (3 vs. 2 days, P = .02). Both groups showed similar positive cumulative percentage weight gains throughout follow-up. These data support the theory of measles as a risk factor for developing diarrhea. The bacteriologic and virologic findings may reflect the immunologic response of the host to measles infection.

Acute Disease↗
PubMed1991

High frequency of coinfecting enteropathogens in Aeromonas-associated diarrhea of hospitalized Peruvian infants.

Rectal swabs from 391 infants less than 18 months of age who were hospitalized with acute diarrhea and from 138 similarly aged healthy infants were examined for the etiologic agents of diarrhea. Aeromonas spp. were recovered from 205 of 391 (52.4%) diarrheic patients, whereas they were recovered from 12 of 138 (8.7%) controls (P less than 10(-11). Among the 205 Aeromonas-positive diarrheic patients, 118 (57.6%) were found to be coinfected with other common enteropathogens. Of the 164 Aeromonas-positive initial diarrheic specimens, 82 (50.0%) had one or more other enteropathogens present; 30 patients were coinfected with rotavirus, 20 with enterotoxigenic Escherichia coli, 16 with Campylobacter spp., 14 with Shigella spp., 13 with enteropathogenic E. coli, 4 with Vibrio spp., 1 with Salmonella spp., and 1 with Plesiomonas spp. of Aeromonas strains from cases compared with that from controls supports an etiologic role for this organism. However, frequent concomitant infections with other well-recognized enteropathogens and a lack of disease correlation with common Aeromonas phenotypes suggest that only a subset of Aeromonas strains may be diarrhea causing and that such strains may be common to several of the existing species.

Aeromonas↗
PubMed1991

Electrocardiographic changes in tetanus: a serial study.

Serial electrocardiograms (ECGs) were recorded in 20 consecutive male patients admitted to the Infectious Diseases Hospital, Calcutta with generalised tetanus. Age of patients varied from 5 to 40 years (mean age 20.4 years). Ten patients died. ECGs were recorded daily for the first week after admission and later every 2nd or 3rd day. Altogether, 167 ECGs were analysed. Sinus tachycardia was present in 17 (85%) patients, prolonged QT interval in 12 (60%) patients, non-specific ST-T abnormalities in 12 (60%) patients and P wave changes in 10 (50%) patients. Other abnormalities recorded, included short PR interval, supraventricular tachycardia, intraventricular conduction delay, sinus bradycardia, 1 degree A-V block, abnormal axis deviation, right ventricular hypertrophy and sino-atrial Wenckebach phenomenon, although all of the findings cannot clearly be attributed to tetanus. Spatial QRS-T angle was calculated in 18 of these patients to determine any possible change in this parameter of prognostic significance. Two out of 9 who survived had abnormally wide (greater than or equal to 55 degrees) spatial QRS-T angle on admission; the angle narrowed with recovery. In the non-survivor group, 4 patients had abnormally wide QRS-T angles on admission; further widening was noted in patients on whom follow-up tracings were available. The difference in spatial QRS-T angle between the survivor and the non-survivor groups was statistically significant (p less than 0.05). Spatial QRS-T angle changes have not been reported in tetanus before. Although non-specific, serial study in individual cases would be useful in assessing prognosis.

Adolescent↗
PubMed1991

Role of a soy-based lactose-free formula in the outpatient management of diarrhea.

The introduction of a soy-based, lactose-free formula during the acute phase of diarrheal illness in infants has been shown to reduce stool output and duration of diarrhea in hospitalized patients. In the United States, most infants with acute diarrhea are treated as outpatients. In the present study, infants with diarrhea who were treated as outpatients were randomly assigned to receive either a soy-based, lactose-free formula alternating with oral rehydration solution from the beginning of therapy ("early feeding") or oral rehydration solution alone for the first 24 hours of therapy, followed by a soy-based, lactose-free formula alternating with oral rehydration solution (control group). Twenty-nine infants were randomly assigned to the early-feeding group and 27 to the control group. Twenty-one (72%) of 29 in the early-feeding group resolved their diarrhea at the end of 48 hours of therapy compared with 12 (44%) of 27 in the group fed oral rehydration solution only (P = .02). It is concluded that the introduction of a soy-based, lactose-free formula from the beginning of therapy for acute diarrhea in children treated as outpatients is safe and may shorten duration of diarrhea while maintaining adequate caloric intake.

Ambulatory Care↗
PubMed1990

A comparison of rice-based oral rehydration solution and "early feeding" for the treatment of acute diarrhea in infants.

To compare the use of rice-based oral rehydration solution (R-ORS), with the introduction of food immediately after rehydration ("early feeding"), using standard glucose-based oral rehydration solution (G-ORS) in the management of acute diarrhea, we conducted a four-cell randomized, controlled trial among 200 hospitalized Egyptian infants between 3 and 18 months of age. During the rehydration phase (first 4 hours), three groups were given G-ORS and a fourth group was given R-ORS. During the subsequent maintenance phase, the control group was given a soy-based, lactose-free formula (G-ORS + SF), a second group (G-ORS + RF) was given a rice-based formula, and a third group (G-ORS + rice) was given boiled rice. The fourth group (R-ORS + SF) continued to receive R-ORS for the first 24 hours of the maintenance period, followed by a soy-based lactose-free formula. During the first and second 24 hours of the maintenance period, infants in the three treatment groups had a lower mean stool output in comparison with the control group (p = 0.006 and 0.03, respectively). The mean total stool output in the R-ORS + SF group was significantly lower than in the control group (p = 0.02). There were no statistically significant differences among the four groups in the mean duration of diarrhea. We conclude that (1) infants who were given R-ORS had reduced total stool output (by 35%) compared with the control group and (2) feeding of boiled rice or a rice-based formula immediately after rehydration therapy was as efficacious as treatment with R-ORS alone for 24 hours, followed by feeding with a soy-based, lactose-free formula.

Acute Disease↗
PubMed1990

Rotavirus diarrhoea in Apache children: a case-control study.

A case-control study of rotavirus diarrhoea in Apache children up to two years old was conducted at the White Mountain Apache reservation from 1 May through 15 December 1985 to identify risk factors for rotavirus diarrhoea. The mothers of fifty cases, forty-five hospital controls and twenty-five neighbourhood controls participated in this study. Exposure to other children with diarrhoea stood out as the single most important factor for acquiring rotavirus diarrhoea (Odds ratio = 14.0). Other significant risk factors were living in homes with septic tanks and in homes with 'poor environmental sanitation.'. Minimizing contacts of children with diarrhoea therefore would be the most effective measure in preventing the spread of this disease in the community.

Arizona↗
PubMed1990

Diarrhea and intestinal invasiveness of Aeromonas strains in the removable intestinal tie rabbit model.

Twelve Aeromonas strains were tested for virulence by using the removable intestinal tie adult rabbit diarrhea model. Mortality was 50% or greater for 7 of 12 strains; 23 of 37 rabbits that died developed diarrhea before death, and 11 of 27 surviving rabbits developed diarrhea. Aeromonas bacteremia was detected in 36 of 37 (97%) animals that died, but only in 2 of 27 (7%) survivors. Death, diarrhea, and bacteremia were all strongly strain dependent. Gastrointestinal lesions varied from moderate focal enteritis to severe multifocal necrosis and hemorrhage of the ileal mucosa, often accompanied by hepatic and splenic lesions. Intestinal colonization assays performed after infection indicated that the ileum was the most heavily colonized portion of the gut and the probable site of invasion. The application of the removable intestinal tie adult rabbit diarrhea model for intestinal challenge with Aeromonas strains has shown that some isolates are capable of invading the mucosa of rabbits, causing diarrhea and bacteremia. These data suggest that such strains may be important in causing human invasive diarrhea.

Aeromonas↗
PubMed1990

Transient intestinal colonization by multiple phenotypes of Aeromonas species during the first week of life.

The intestinal colonization rate of Aeromonas spp. was determined for 52 cesarean-born Peruvian neonates. Rectal swabs were obtained daily from newborns during their postdelivery hospitalization (mean = 5.5 days), and the gross appearances of their feces (blind determinations) were recorded. Aeromonas spp. were recovered from rectal swabs of 12 of 52 (23.1%) infants during their first week of life; the isolates were obtained from 5 of 9 (55.6%) infants with at least one stool with a watery consistency and from 7 of 43 (16.3%) neonates with no watery stools (P = 0.022). None of the infected infants became clinically ill. No other commonly recognized enteropathogens were detected in watery stools. An environmental survey indicated that hospital water was the probable source of infection. These and other data indicated that Aeromonas colonization occurs transiently at a very early age in Peruvian neonates and that in some instances, initial infection may be followed several days later by one or more watery stools of normal volume.

Aeromonas↗
PubMed1989

Comparison of single-dose treatment with norfloxacin and standard 5-day treatment with trimethoprim-sulfamethoxazole for acute shigellosis in adults.

Shigellae have been shown to be highly susceptible to new quinolone agents, with average MICs for 90% of isolates of less than 0.1 microgram/ml. Because these agents also reach high concentrations in the stool after a single dose, the effectiveness of a single 800-mg dose of norfloxacin and of 5-day treatment with trimethoprim-sulfamethoxazole (TMP-SMX) were compared in a randomized trial. Patients with clinical dysentery received one of these treatment regimens, and clinical data and follow-up culture results were analyzed for patients whose stool culture on presentation grew shigellae. When 55 patients with shigellosis (26 treated with TMP-SMX, 29 treated with norfloxacin) whose bacterial isolates were susceptible to the antibiotic given were compared by treatment group, no significant differences were seen in days of illness (mean, 2.5 +/- 0.65 days with TMP-SMX and 2.0 +/- 0.47 days with norfloxacin; P = 0.200) or number of unformed stools after starting treatment (mean, 9.7 +/- 2.37 stools with TMP-SMX and 7.6 +/- 3.19 stools with norfloxacin; P = 0.312). Resistance in vitro to TMP-SMX was seen in 15% of Shigella isolates, whereas none was resistant to norfloxacin. Bacteriologic failure was found in 1 patient among 24 receiving TMP-SMX and in none of 25 patients receiving norfloxacin. One single dose of norfloxacin was as effective as 5 days of treatment with TMP-SMX in these adults with shigellosis.

Adult↗
PubMed1988

Effect of continued oral feeding on clinical and nutritional outcomes of acute diarrhea in children.

One hundred twenty-eight nonmalnourished male patients between 3 and 36 months of age were randomly assigned to receive one of four lactose-free dietary treatments to determine the effect of dietary therapy on the severity and nutritional outcome of diarrheal illness. Group 1 received a formula diet composed of casein, sucrose, dextrin with maltose (Dextri-Maltose), and vegetable oil to provide 110 kcal/kg body weight/d (CSO-110). Group 2 received CSO to provide 55 kcal/kg/d (CSO-55) for 2 days and then CSO-110. Group 3 received only oral glucose-electrolyte solution (GES) for 2 days, CSO-55 for the next 2 days, and then CSO-110. Group 4 received the same diets as Group 3 except that only intravenous GES was used for the first 2 days. The GES maintenance solutions provided 24 to 30 kcal/kg/d. Therapeutic success rates were similar among dietary groups, ranging from 90% to 97%. Fecal excretion was initially lower in group 4 (P less than 0.05) but was similar initially among groups treated orally and among all four groups beginning on day 3. Net apparent absorption of nitrogen, fat, carbohydrate, and total energy; retention of nitrogen; and increments in body weight, arm circumference, and skin-fold thickness were positively related to the amounts of dietary energy consumed. Thus continued oral feeding with the CSO diets during the early phase of therapy yielded improved nutritional results.

Absorption↗