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Biomedical subjects

S Sorger

Publications and source records attributed to S Sorger.

10 recordsLinked to original sources

Assessment of gelatin supplementation of PEDS Plus BACTEC blood culture medium.

Gelatin supplementation of blood culture media has been shown to neutralize the effects of sodium polyanetholesulfonate and enhance detection of Neisseria species. We evaluated the effect of 1.2% gelatin supplementation of nonradiometric Peds Plus Bactec blood culture medium on the rate and speed of recovery of pathogens from pediatric patients. From June 1991 to June 1992, a total of 6451 paired comparisons of blood cultures in Peds Plus medium and gelatin-supplemented Peds Plus medium were done: 465 organisms were isolated, of which 338 were significant. There were no significant differences in recovery of organisms or the speed of detection of microbial growth between the two media. In particular, the recovery of Neisseria meningitidis (eight isolates) was not improved with gelatin supplementation. In conclusion, gelatin supplementation of Peds Plus Bactec medium does not offer any advantage over the regular Peds Plus Bactec medium.

Bacteremia↗

Pneumococcosuria in children.

Streptococcus pneumoniae was present, in pure or mixed culture, in 43 (0.08%) of 53,499 urine cultures submitted from a pediatric population over a 4-year period. Data were analyzed from 28 children, from whom 78% of these positive cultures originated. Ninety-six percent of the children were female, and the median age was 3 years (range, 0.4 to 17 years). Only five children had S. pneumoniae as the sole organism cultured from the urine, and all five had only a single urine culture. Urine from the other 23 children contained other organisms as well. Small numbers of pneumococci were found in most urines: 74% contained less than 10(4) CFU/ml and 93% contained less than 10(5) CFU/ml. There was no association between genitourinary symptoms and pneumococcosuria, and complete resolution of symptoms occurred in both treated and untreated children. Pneumococcosuria could not be explained by pneumococcal bacteremia. We conclude that pediatric pneumococcosuria is not associated with urinary tract infections in children, or with pneumococcal bacteremia or invasive disease elsewhere. Pneumococcosuria probably reflects contamination of urine specimens with S. pneumoniae from perineal colonization.

Adolescent↗

Free thiol groups and labile disulfide bonds in the IgG fraction of human serum.

The IgG fraction was isolated from freshly taken blood serum of health persons (male and female) by column chromatography on QAE-Sephadex. After 30 min incubation with DTNB (5,5'-dithio-(2,2'-dinitro)-benzoate) the average photometrically determined quantity of thio-anions was 0.24 +/- 0.02 SH/mole IgG. Since this result remained unchanged even after 24 h incubation with DTNB, interaction with masked thiol groups cannot be assumed. If, however, the serum was incubated with DTNB for 24 h and the IgG fraction then isolated and treated with thioglycolate, an average of 1.51 +/- 0.39 moles of thio-anions were liberated per mole of IgG. This indicates that on 24 h interaction with IgG, DTNB not only reacts with free SH groups, but also opens S-S bonds by a disulfide exchange reaction. The amount of thio-anions resulting from such opened disulfide bonds was calculated as the difference between 1.51 0.24, i.e., 0.64 S-S/mole IgG. This would be accounted for if approximately 54% of the IgG fraction is composed of a subfraction containing 1 labile disulfide bone per mole. The average of 1.51 thio-anions per mole IgG resulted from 130 single values with an essentially normal statistical distribution and standard deviation well within the usual biological range.

Chemical Fractionation↗

Enhancement of recovery of Neisseria meningitidis by gelatin in blood culture media.

The efficacy of gelatin for the recovery of Neisseria meningitidis from blood cultures was evaluated in a clinical setting. The organism was isolated from seven patients with meningococcal infections in blood culture media containing 1% gelatin. In contrast, only two blood cultures from these patients were positive in media without gelatin (P less than 0.05). Gelatin did not influence the recovery of other organisms isolated during this study. Conventional blood culture media may be supplemented with gelatin when meningococcemia is suspected.

Blood↗

Efficacy of cold enrichment techniques for recovery of Yersinia enterocolitica from human stools.

Stool specimens from children with gastroenteritis and their household contacts were cultured for Yersinia enterocolitica by direct plating onto routine laboratory media. These stools were also inoculated into phosphate-buffered saline and subcultured to the same media after 1 day or 3 weeks of incubation at 4 degrees C. Y. enterocolitica was isolated from 174 index cases and 34 household contacts. One hundred eighty-one isolates were of serotype O:3, and the remaining 21 belonged to other serotypes. Eighty-one percent (147/181) of O:3 isolates were recovered by direct plating, and 6.1% (11/181) and 13% (23/181) were recovered by 1-day and 3-week cold enrichment, respectively. For other serotypes, 26% (7/27), 0%, and 74% (20/27) were isolated by direct plating, 1-day cold enrichment, and 3-week cold enrichment, respectively. The efficacy of the cold enrichment for the patients were still symptomatic, 94 and 6% of Y. enterocolitica were identified by direct plating and cold enrichment, respectively. Isolation rates were 66% by direct plating and 34% by cold enrichment when stools were obtained from asymptomatic carriers or from those convalescing from Y. enterocolitica gastroenteritis. These results indicate that the cold enrichment methods increase the sensitivity of Y. entercolitica culture methods considerably in convalescent and asymptomatic subjects but only minimally in patients with diarrhea caused by serotype O:3.

Bacteriological Techniques↗

Assessment of gelatin-supplemented BACTEC blood culture medium in a pediatric hospital.

Sodium polyanetheolesulfonate (SPS), an anticoagulant used in blood culture media, adversely affects the isolation of Neisseria meningitidis. The addition of gelatin appears to counteract this effect. Studies using the radiometric BACTEC system, however, have noted a lower isolation rate of other bacteria from gelatin-supplemented media. We wished to evaluate the effect of the addition of gelatin (1.2%) to a nonradiometric BACTEC aerobic medium (NR6A) on the recovery of N. meningitidis and other pathogens. The NR6A medium with gelatin (NR6A analogue) also contained a lower concentration of SPS (0.025% vs 0.035%). We did 6045 paired comparisons of blood cultured in routine NR6A medium and the NR6A analogue. Eight isolates of N. meningitidis were recovered, five only from the gelatin-supplemented medium and three from both bottles. There was no statistically significant difference in total recovery of aerobic and facultative bacteria or Candida species from both bottles. Haemophilus influenzae was detected earlier in the nonsupplemented NR6A medium. We conclude that the use of the NR6A analogue medium appeared to increase the yield of N. meningitidis without adversely affecting the recovery of other common pathogens, although the recovery of H. influenzae was slightly delayed.

Anticoagulants↗