The diagnosis of anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis relies on the detection of NMDAR IgG autoantibodies in the serum or cerebrospinal fluid (CSF) of symptomatic patients. Commercial kits are available that allow NMDAR IgG autoantibodies to be measured in local laboratories. However, the performance of these tests outside of reference laboratories is unknown.

To report an unexpectedly low rate of NMDAR autoantibody detection in serum from patients with anti-NMDAR encephalitis tested using a commercially available diagnostic kit in an exemplar clinical laboratory.

Paired CSF and serum samples from seven patients with definite anti-NMDAR encephalitis were tested for NMDAR IgG autoantibodies using commercially available cell-based assays run according to manufacturer’s recommendations. Rates of autoantibody detection in serum tested at our center were compared with those derived from systematic review and meta-analyses incorporating studies published during or before March 2019.

NMDAR IgG autoantibodies were detected in the CSF of all patients tested at our clinical laboratory but not in paired serum samples. Rates of the detection were lower than those previously reported. A similar association was recognized through meta-analyses, with lower odds of NMDAR IgG autoantibody detection associated with serum testing performed in nonreference laboratories.

Commercial kits may yield lower-than-expected rates of NMDAR IgG autoantibody detection in serum when run in exemplar clinical (nonreference) laboratories. Additional studies are needed to decipher the factors that contribute to lower-than-expected rates of serum positivity. CSF testing is recommended in patients with suspected anti-NMDAR encephalitis.

To evaluate the impact of changes to urine testing orderables in computerized physician order entry (CPOE) system on urine culturing practices.

Retrospective before-and-after study.

A 1,250-bed academic tertiary-care referral center.

Hospitalized adults who had ≥1 urine culture performed during their stay.

The intervention (implemented in April 2017) consisted of notifications to providers, changes to order sets, and inclusion of the new urine culture reflex tests in commonly used order sets. We compared the urine culture rates before the intervention (January 2015 to April 2016) and after the intervention (May 2016 to August 2017), adjusting for temporal trends.

During the study period, 18,954 inpatients (median age, 62 years; 68.8% white and 52.3% female) had 24,569 urine cultures ordered. Overall, 6,662 urine cultures (27%) were positive. The urine culturing rate decreased significantly in the postintervention period for any specimen type (38.1 per 1,000 patient days preintervention vs 20.9 per 1,000 patient days postintervention; P < .001), clean catch (30.0 vs 18.7; P < .001) and catheterized urine (7.8 vs 1.9; P < .001). Using an interrupted time series model, urine culture rates decreased for all specimen types (P < .05).

Our intervention of changes to order sets and inclusion of the new urine culture reflex tests resulted in a 45% reduction in the urine cultures ordered. CPOE system format plays a vital role in reducing the burden of unnecessary urine cultures and should be implemented in combination with other efforts.