Do published guidelines predict pneumonia in children presenting to an urban ED?

OBJECTIVES: In 1997, a Canadian task force published evidence-based guidelines for diagnosing pediatric pneumonia, concluding that the absence of each of four signs (ie, respiratory distress, tachypnea, crackles, and decreased breath sounds) accurately excludes pneumonia. The study was performed to evaluate the accuracy of these guidelines in predicting pneumonia in young children. METHODS: This was an observational study conducted over a 4-month period at an urban emergency department with 80,000 annual visits, approximately 20% of which were children < or =5 years old. Consecutive children < or =5 years old who underwent chest radiography were enrolled. Prior to ordering radiographs, treating physicians were required to enter specific patient signs and symptoms into a computerized database. World Health Organization criteria were used to define tachypnea. Sensitivity, specificity, and predictive values of the task force guidelines in predicting pneumonia were calculated. RESULTS: Three hundred twenty-nine children, including 67 (20%) with pneumonia, were enrolled. Guidelines were 45% sensitive (95% confidence interval (CI) = 33-58) and 66% specific (95% CI = 60-72) for diagnosing pneumonia. Positive and negative predictive values were 25% (95% CI = 18-34) and 82% (95% CI = 77-87), respectively. CONCLUSION: Previously published evidence-based guidelines for excluding pediatric pneumonia were found unreliable in this study.

Minimum detectable level of Salmonellae using a binomial-based bacterial ice nucleation detection assay (BIND).

A modified bacterial ice nucleation detection (BIND) assay was used for rapid and sensitive detection of several Salmonella species. For the BIND assay, Salmonella cells are infected with bacteriophage genetically modified to contain DNA encoding an ice nucleation protein (INP). After infection, de novo protein synthesis occurs and INPs are incorporated into the outer membrane of the organism. After supercooling (-9.3 degrees C), only buffer solutions containing transfected salmonellae freeze, causing a phase-sensitive dye to change color. This technique, and a probability-based protocol modification, provided quantitative detection with a minimum detectable level (MDL) of 2.0 +/- 0.3 S. enteritidis cells/mL in buffer (about 3 h). The MDLs for S. typhimurium DT104 and S. abaetetuba were 4.2 +/- 0.2 and 11.1 +/- 0.4 cells/mL, respectively. Using salmonellae-specific immunomagnetic bead separation technology in conjunction with the modified BIND protocol, we achieved an MDL of about 4.5 S. enteritidis cells/mL with an apparent capture efficiency of 56%.

Revised model for aerobic growth of Shigella flexneri to extend the validity of predictions at temperatures between 10 and 19 degrees C.

Although Shigella is a major foodborne pathogen, its growth in foods has received little attention. Growth of S. flexneri 5348 inoculated into commercially available sterile foods (canned broths, meat, fish, UHT milk, baby foods) was studied at 10 to 37 degrees C. S. flexneri was enumerated by surface-plating on Tryptic Soy Agar and growth curves were fitted by means of the Gompertz equation. Observed growth kinetics values and values calculated using a previously developed response surface model compared favorably for growth at 19 to 37 degrees C, but not at < 19 degrees C. To refine the model, additional data were collected for growth at 10 to 19 degrees C. A total of 844 tests in BHI broth, representing 197 variable combinations of temperature (10-37 degrees C), pH (5.0-7.5), NaCl (0.5-5.0%) and NaNO2 (0-1000 ppm) was used for the revised model. The revised model, developed in BHI, gave significantly better agreement of calculated growth kinetics values with those observed in foods at 10 to 19 degrees C.

Delayed lactogenesis in women with insulin-dependent diabetes mellitus.

Breast milk lactose, total nitrogen, conductivity, osmolality, and intake by infants of 33 women with insulin-dependent diabetes mellitus (IDDM), 33 control women without diabetes, and 11 reference women were determined in a 3-mo study of lactation. Milk of women with IDDM had significantly lower lactose and higher total nitrogen (2-3 d postpartum), and their infants had significantly less milk intake (7-14 d postpartum) than did control or reference women. Total nitrogen was negatively correlated with milk lactose for women with IDDM at all times and for control women through day 14 postpartum. The data indicate delayed lactogenesis for women with IDDM, which was more likely to occur with poor metabolic control. Differences in milk composition of women with IDDM do not preclude them from breast-feeding their infants.