We conducted a cross-sectional study of 79 children attending seven day care centers in Houston, Texas, to detect fecal gram-negative bacilli resistant to trimethoprim (TMPr) and ampicillin (AMPr). Fifteen children (19%) were colonized with TMPr Escherichia coli; all but one strain were also resistant to sulfonamides. Most of the children with TMPr E. coli were clustered in center A, where 11 (37%) of 30 children were colonized; only four (8%) of 49 children in the other six centers were colonized with TMPr E. coli (P less than .005). The TMPr E. coli isolates from 10 of the 11 children in Center A had a similar antibiogram, which included resistance to sulfonamides, ampicillin, and streptomycin; eight had a similar total plasmid pattern, an observation suggesting spread within the day care center. Children colonized with AMPr E. coli were present in all centers, although a higher percentage of children in center A were colonized than in the other centers combined (70% vs. 35%; P less than .01).
Racecadotril resolved the symptoms of acute diarrhoea rapidly and effectively, and produced more rapid resolution of abdominal symptoms and less constipation than loperamide.
The relation between in vitro production of HeLa cell cytotoxin by strains of Shigella and clinical symptomatology was determined for 35 travelers from the United States who developed shigellosis in Guadalajara, Mexico. There were 25 patients with Shigella sonnei, eight with Shigella flexneri, one with Shigella boydii, and one with Shigella dysenteriae. These strains were evaluated for in vitro production of cytotoxin. The amount of cytotoxin did not correlate with the number of stools passed, the severity of abdominal pain, or the presence of nausea or vomiting. However, patients with strains of Shigella that produced more cytotoxic activity were more likely to have fever (P less than .02) and occult blood in their stools (P less than .004). The cytotoxicity produced by 30 (86%) strains could not be neutralized with rabbit antiserum to purified, formaldehyde-treated Shiga toxin from S. dysenteriae type 1 strain 60 R; the cytotoxicity of five (14%) of the strains was partially neutralized. When only nonneutralizable cytotoxin was considered, the presence of fecal leukocytes (P less than .04), as well as of occult blood (P less than .002) and fever (P less than .02), correlated with the amount of cytotoxin. The amount of nonneutralizable cytotoxin produced by shigella strains was related to the clinical findings. This cytotoxic activity was infrequently attributable to "Shiga toxin".
We measured the cytotoxic activity of 119 strains of Shigella by using a quantitative [3H]thymidine-labeled HeLa cell assay. We assayed 13 strains of Shigella dysenteriae 1; 18 strains of S. dysenteriae types 2 and 3; and 88 strains of Shigella sonnei, Shigella flexneri, and Shigella boydii. Strains of S. dysenteriae 1 demonstrated high levels of cytotoxicity (geometric mean, 10(5.04) CD50/mg of protein; range, 10(3.95)-10(6.10). Cytotoxic activities of the non-type 1 strains of S. dysenteriae and of the other Shigella serogroups were approximately 1/1,000 that of the S. dysenteriae 1 strains (range, 10(1.09)-10(3.11) CD50/mg of protein). Neutralization of cytotoxicity by using rabbit antiserum to purified Shiga toxin revealed that in all strains of S. dysenteriae 1, greater than or equal to 99.5% of cytotoxic activity was attributable to Shiga toxin. In contrast, 88 of the other Shigella strains produced only nonneutralizable cytotoxic activity. Six of 18 strains of non-type 1 S. dysenteriae and 12 of 88 strains from other Shigella serogroups produced both Shiga toxin and nonneutralizable toxin.
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