Immunoelectrochemical assays for bacteria: use of epifluorescence microscopy and rapid-scan electrochemical techniques in development of an assay for Salmonella.

Immunoelectrochemical sensors in which the sensor surface functions as both analyte capture phase and electrochemical detector have recently been developed for bacteria analysis. The speed and sensitivity of these devices make them very attractive for applications such as the detection of pathogenic microorganisms in food and water. However, the development and optimization of assays utilizing these sensors can be complicated by undesired interactions between the capture and detection functions. Modification of the sensor to achieve improvements in one function can have deleterious effects on the other function, and such effects can be difficult to diagnose and correct. In the course of investigations on immunoelectrochemical detection of Salmonella, we developed a rapid, nondestructive epifluorescence microscopy method to determine bacteria capture efficiency. This method enabled us to study capture and detection functions independently and efficiently identify performance-limiting factors. Rapid-scan electrochemical methods were used to optimize detection sensitivity and to provide diagnostic information on detection performance.

Enzyme-linked immunomagnetic electrochemical detection of Salmonella typhimurium.

There is a need for rapid methods to detect pathogenic bacteria in food products as alternatives to the current laborious and time-consuming culture procedures. We report a microbial detection technique that combines the selectivity of antibody-coated superparamagnetic beads with the rapidity and sensitivity of electrochemical detection in a format termed enzyme-linked immunomagnetic electrochemistry. In it, Salmonella typhimurium were sandwiched between antibody-coated magnetic beads and an enzyme-conjugated antibody. With the aid of a magnet, the beads (with or without bound bacteria) were localized onto the surface of disposable graphite ink electrodes in a multi-well plate format. Enzyme substrate was added and conversion of substrate to an electroactive product was measured using electrochemical detection. The electrochemical response was directly proportional to the number of captured bacteria. Using this technique, a minimum detectable level of 8 x 10(3) cells/ml of Salmonella typhimurium in buffer was achieved in ca. 80 min.

The social context of teenage childbearing: effects on the infant's care-giving environment.

PIP: 50 low-middle socioeconomic status (SES), primiparous, US Caucasian mothers and their full-term healthy infants were included in a study of the effects of maternal age and the social context on the home environment, and maternal behaviors of adolescent and older mothers, as well as the stability of the care-giving environment. At 4 months, support systems and life stress were assessed, as well as the home environment and maternal behaviors. At 2 years, a similar home visit was conducted in a subsample. Adolescent mothers had less education, lower SES, and a different child care support system. They also differed in the home environment and maternal behaviors at 4 months. Some of these differences disappeared when maternal education and SES, or child care support and life stress, were controlled. Moderate correlations were observed between 4 months and 2 years home environment and maternal verbalizations. Thus, a combination of maternal age and other social factors mediate the negative characteristics of the adolescent mother's care-giving environment, which is relatively stable during the infancy period.^ieng