Verocytotoxin-producing Escherichia coli in patients with diarrhoea in Switzerland.

The present study was conducted between October 1996 and October 1998 to estimate the frequency of verocytotoxin-producing Escherichia coli among outpatients with diarrhoea in Switzerland. Among 3,041 subjects studied, 16 (0.5%) verocytotoxin-producing Escherichia coli infections were identified. Eleven cases were in infants and children

Immobility as a major cause of bone remodeling in residents of a long-stay geriatric ward.

Residents of a long-stay geriatric ward at the University Hospital Basel were included in a study to investigate the effects of hypovitaminosis D and immobility. All 91 women (mean age 82.5 years) and 92 men (mean age 78.7 years) were enrolled in the study. Measurements included bone resorption, as measured by urinary deoxypyridinoline (dpd), serum 25-hydroxyvitamin D (25OHD), serum intact parathyroid hormone (iPTH), and their correlations with a four grade mobility score. Mobility score reflected the degree of weight bearing, ranging from walking independently to primarily bed bound. In 86% of all residents, serum 25OHD levels were below the normal limit of 12 ng/ml. Secondary hyperparathyroidism (HPT) was detected in 24% of all patients, using 55 pg/ml as the upper limit for serum iPTH. No significant correlation was found between urinary dpd and serum 25OHD or serum iPTH. Mobility index and both urinary dpd (f: P = 0.001, r = 0.37; m: P < 0.0001, r = 0.47) and serum calcium (female: P = 0.007, r = 0.28; male: P = 0.02, r = 0.24) were positively related. In institutionalized elderly people with a high prevalence of vitamin D deficiency serum intact PTH levels did not correlate with bone resorption as measured by urinary deoxypyridinolin. However, more immobile subjects had significantly higher excretion rates for urinary dpd and higher serum calcium levels. Our results suggest that in elderly people immobility may contribute to bone loss that might preempt the development of secondary HPT through elevation of serum calcium.

Faulty washers and soiled micropipettors may generate false positive serological results.

BACKGROUND: Serological markers such as HBsAg and anti-HIV may be present in serum at very high concentrations and this may give rise to erroneous diagnoses due to cross-contamination. OBJECTIVES: To investigate poor equipment maintenance and use, including contamination with human serum, as a potential source of erroneous assay results. STUDY DESIGN: The potential of microtitre plate washers and micropipettors to transfer material between microplate wells and between specimens was examined. For the study of micropipettors we recruited 19 UK diagnostic laboratories. RESULTS: Four out of seven plate washers in use, until adjusted, had the potential to cause false positive HBsAg reactions. The centering of the probes that delivered the wash fluid, delivery pressure, wash volume and the use of a pre-programmed card to direct the washing procedure were important variables. We investigated soiling of tip cones of micropipettors. In every laboratory human IgG could be detected in at least a third of eluates from micropipettor tip cones; only 31 (14%) of 222 showed no evidence of contamination with human serum. Only one laboratory submitted eluates devoid of specific antibodies. Anti-HAV was the marker most commonly found (n = 68), followed by HBsAg (n = 27) and anti-HIV (n = 20). Seven micropipettor eluates from two laboratories were radioactively contaminated. CONCLUSIONS: Recommended precautions are regular checking, cleaning and servicing of equipment, care in interpreting weak reactions, reference back to serum left on the clot of the original specimen and testing of a follow up specimen. Poorly maintained immunoassay equipment can readily generate false positive results due to low-level cross-contamination, particularly with the current highly sensitive HBsAg and anti-HIV assays.