Multicenter study of an erythro-aggregometer: quality control and standardization.

There is a need for quality assurance procedures in hemorheology, especially for clinical and pharmacological studies, which require reliable and well-calibrated instruments to be interpretable and comparable. Preliminary investigations allowed preparation of standardized SM (normal NS and hyperaggregable HS), and checking of storage conditions (in accordance with the guidelines of the SSC of ISTH) of RBC in nutritive SAG mannitol for at least 2 or 3 weeks with subsequent washings and resuspension in SM. In our study, we compared erythro-aggregometers of the same brand in 6 laboratories, using the same red blood cells (RBC) and suspending media (SM) for each series of tests. EA was measured by laser backscattering with determination of aggregation time (AT), partial dissociation threshold (PDT) and aggregation index (AI). Prior to the study, devices were set up on the same day with the same standardized blood, and calibration data were then analyzed. Within-assay precision (WAP) was assessed on 3 days for the 2 types of SM (n = 18 x 2). Between-assay precision (BAP) was assessed on 6 occasions, once every month (n = 6 x 2 x 6). Accuracy was studied with 3 series of RBC resuspended in 10 SM of "unknown" aggregability. Good agreement was observed between 5/6 centers for the 3 parameters of EA. WEP was good: CV of AT ranging from 1.4 to 2.5% for the NS and from 1.4 to 2.4% for the HS. In each center, BAP was slightly lower than WEP (CV: 8-11.8% for the NS and 3.8-4.7% for the HS over the 6-month study), with no drift, except for one center. Precision was always better with the HS than with the NS which seemed a better tool to assess it. As to accuracy, non-significant differences were generally found between centers, with similar data to the reference values. This work also stressed the importance of the RBC parameter itself in rheological data. For the first time, a protocol for standardization of EA has been developed and evaluated, permitting the Quality Control of this technique.

[Bacteriologic surveillance of nosocomial septicemia and bacteremia in a pediatric hospital]. / Surveillance bactériologique des septicémies et bactériémies nosocomiales dans un hôpital pédiatrique.

BACKGROUND: Nosocomial bloodstream infections in pediatrics are an important cause of morbidity and mortality. To identify pathogens causing nosocomial bloodstream infections, evaluate associated risk factors and take preventive measures, we conducted a prospective study from January 1995 to December 1995 at Saint-Vincent-de-Paul Hospital (Paris). PATIENTS AND RESULTS: All patients hospitalized more than 48 hours were included in the study. During this period, we recorded 21 bloodstream infections in 20 children. The incidence rate of nosocomial bloodstream infection was 1/1,000 admissions. Sixteen children were hospitalized in surgery, three in medical intensive care unit; the median day onset of infection was approximately 20 days. Recorded risk factors were: surgery, invasive procedures, central catheterization, bladder catheters, parenteral nutrition, device, endotracheal tube, antibiotic therapy before infection. The number of risk factors ranged from zero to six per patient. The most common isolated pathogens were in ten cases Gram positive cocci: five methicillin-sensible Staphylococcus aureus, four methicillin-resistant coagulase-negative staphylococci and one Streptococcus milleri. Other bacteria were seven enterobacteria, three Pseudomonas sp and three Candida sp. In 11 cases, the same bacteria as in bloodstream infection could be found: in three urine samples, in two tracheal samples, in two gastro-intestinal samples, two puncture sites, one device, and one umbilical catheter. CONCLUSION: In our study, 6.2% of positive blood culture were due to a nosocomial infection. We confirm the importance of Gram positive cocci, and particularly of methicillin-resistant coagulase negative staphylococci.

[Nosocomial bacteremias in pediatrics]. / Bactériémies nosocomiales en pédiatrie.

OBJECTIVES: To identify pathogenic microorganisms responsible for hospital-acquired bloodstream infections and to evaluate the associated risk factors in pediatric units, in a case-control study over 30 months from January 1st 1997 to June 30th 1999. RESULTS: Forty-six of 855 (5.4%) positive blood cultures were attributed to nosocomial infections. They were related to 32 infectious episodes in 28 patients hospitalized for more than 48 hours. The incidence rate was 0.11 per 100 admissions. Gram-positive cocci (n = 14; 38.8%) were the most frequently isolated pathogens (7 cases of Staphylococcus aureus, 5 of coagulase-negative staphylococci), followed by enterobacteria (n = 9; 25%), Pseudomonas aeruginosa (n = 5; 13.8%) and yeasts (n = 5; 13.8%). The major risk factors for hospital-acquired bloodstream infections were: length of stay before positive blood culture (32 +/- 51 days in cases vs 15 +/- 43 days in controls, p < 0.01), presence of central venous catheter [odds ratio (OR): 6.05, 95% confidence interval (CI): 1.87-20.42], number of days with central venous catheter (p < 0.001) and parenteral nutrition (OR: 9.44, 95% CI: 2.03-50.05). CONCLUSION: Central venous catheter use, length of stay, parenteral nutrition and particularly intravenous lipids are major risk factors for the acquisition of bloodstream infection in hospitalized children.