Impact of the introduction of a nucleic acid amplification test for Clostridium difficile diagnosis on stool rejection policies.

BACKGROUND: The change from non-molecular to nucleic acid amplification tests (NAATs) is known to increase the detection of Clostridium difficile infection (CDI); however, the impact on stool rejection policies in clinical laboratories is unclear. The current guidelines have reinforced the importance of respecting strict conditions for performing tests on stool samples for CDI diagnosis. The purpose of this study was to estimate whether the implementation of molecular tests has resulted in changes in stool rejection policies between clinical laboratories that introduced NAATs and those that did not. RESULTS: A survey was conducted to evaluate the change in the number of stool samples rejected and the rejection criteria among 12 hospital laboratories in southwestern France before and after the switch from non-molecular tests to NAATs using retrospective data from June 1 till September 30, 2013 and the same period 2014. Four laboratories introduced NAATs as a second or third step in the process. A total of 1378 and 1297 stools samples were collected in 2013 and 2014, respectively. The mean number of rejected stool samples significantly increased (p < 0.001, Chi square test), with a total of 99 (7.1%) and 147 (11.3%) specimens rejected in 2013 and 2014, respectively. Notably, these laboratories had more stringent criteria and were no longer testing the stool samples of patients with CDI-positive results within 7 days. In contrast, there was a significant decrease in the rate of rejected stool samples (p < 0.001, Chi square test) in the five laboratories that did not adopt NAATs and a less stringent stool rejection policy. CONCLUSION: Nucleic acid amplification test implementation improved compliance with recommended stool rejection policies. Laboratories should follow the recommended laboratory algorithm for the CDI diagnosis combined with the correct stool rejection policy.

Comparison of a novel chemiluminescent based algorithm to three algorithmic approaches for the laboratory diagnosis of Clostridium difficile infection.

BACKGROUND: Rapid commercial assays, including nucleic acid amplification tests and immunoassays for Clostridium. difficile toxins, have replaced the use of older assays. They are included in a two-step algorithm diagnosis, including first the detection of the glutamate dehydrogenase (GDH) as a screening method and second the detection of toxins as a confirmatory method. Although assays that detect the presence of free toxins in feces are known to lack sensitivity, they are preferable to confirm infection. We evaluated the accuracy of the chemiluminescence-based method detecting C. difficile GDH and free toxins A/B (DiaSorin algorithm) to an enzyme-immunoassay (EIA) for GDH with a molecular toxins test (Meridian algorithm), EIA-GDH and an EIA-toxins A/B algorithm (Alere algorithm) with and without toxigenic culture for confirmation. FINDINGS: A total of 468 diarrhoeal and loose stool samples were included in the study. A positive result was defined by a positive GDH and a positive toxin test. Discordant samples were resolved using an enriched toxigenic culture considered as the reference method. After resolution, the DiaSorin algorithm showed a high sensitivity (86.7 %) compared to that of the Alere algorithm with (60.0 %) and without (50.0 %) confirmation by culture and was as sensitive as the Meridian algorithm (90.0 %), while the specificities were similar: 99.1, 99.5, 99.5 and 98.9 %, respectively. CONCLUSIONS: The DiaSorin algorithm was as sensitive as an algorithm including nucleic acid amplification test for toxins. Chemiluminescence toxin-enhanced signal assay compensates the lack of sensitivity usually observed for EIA tests for toxins.

A comparative analysis of the center of gravity and center of pressure trajectory path lengths in standing posture: an estimation of active stiffness.

The center of foot pressure (CP) motions, representing the net neuromuscular control, was compared to the center of gravity (CG) motions, representing the net performance. The comparison focused on the trajectory path length parameter along the medio-lateral and antero-posterior axes because these two variables depend on amplitude versus frequency relationship. This relationship was used to evaluate the CG motions based on the CP motions. Seven subjects stood still on a force plate with eyes open and eyes closed. The results showed that the ratio of (CP-CG)/CP trajectory path length was personal for each subject. These results suggest different levels of passive (ligaments, elastic properties) and active (reflex activity) stiffness. For some subjects, this ratio was significantly lower for the eyes open condition than for the eyes closed condition, indicating a decrease of the active stiffness for the eyes open condition. Therefore, a CG-CP comparative analysis appeared helpful in understanding the control of balance and necessary to quantify the subjects' net performance.

Three-dimensional joint moments analysis in a vertical quadrupedal posture associated with a leg release.

This study reports on rock climbers biomechanical adjustments following a leg release from a quadrupedal vertical initial stance. Six climbers of international level have been studied. They were asked to maintain a quadrupedal posture on artificial holds equipped with strain gauges and then to release their right foot. The results show that all the rock climbers adjust differently the vertical forces and the horizontal forces on the holds. They distribute the vertical forces over the three remaining holds and the horizontal forces over the controlateral holds. A quasi-static three-dimensional multi-segment model was used to produce the net reaction forces and joint moments at each joint. Moment results enhance the role of the controlateral limbs, particularly the left leg. The gravity seems to be counteracted at the left knee joint, while body balance seems to be managed at the left hip and ankle joints.

Effect of initial posture on biomechanical adjustments associated with a voluntary leg movement in rock climbers.

This study compares the biomechanical adjustments following a leg displacement in vertical and horizontal position on expert rock climbers. The results show a non-diagonal pattern in the vertical condition and a diagonal one in the horizontal condition. A multi-link analysis shows that the non-diagonal pattern displayed by expert climbers in the vertical condition resulted in a new distribution of body weight to preserve the possibility of moving any limb from the three legged stance. Conversely, in the horizontal condition, the diagonal pattern appears to be strongly dominated by mechanical and anthropometric factors.