Creation of an In-House Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry Corynebacterineae Database Overcomes Difficulties in Identification of Nocardia farcinica Clinical Isolates.

Nocardiosis is a rare disease that is caused by Gram-positive actinobacteria of the Nocardia genus and affects predominantly immunocompromised patients. In its disseminated form, it has a predilection for the central nervous system and is associated with high mortality rates. Therefore, prompt identification of the pathogen is critical. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry is a relatively novel technique used for identification of microorganisms. In this work, an upgraded MALDI-TOF Biotyper database containing Corynebacterineae representatives of strains deposited in the Polish Collection of Microorganisms was created and used for identification of the strain isolated from a nocardial brain abscess, mimicking a brain tumor, in an immunocompetent patient. Testing with the API Coryne system initially incorrectly identified Rhodococcus sp., while chemotaxonomic tests, especially mycolic acid analysis, enabled correct Nocardia identification only at the genus level. Subsequent sequence analysis of 16S rRNA and secA1 genes confirmed the identification. To improve the accuracy of the results, an in-house database was constructed using optimized parameters; with the use of the database, the strain was eventually identified as Nocardia farcinica. Clinical laboratories processing various clinical strains can upgrade a commercial database to improve and to accelerate the results obtained. This is especially important in the case of Nocardia, for which valid microbial diagnosis remains challenging; reference laboratories are often required to identify and to survey these rare actinobacteria.

Accuracy of the Free-hand Placement of Pedicle Screws in the Lumbosacral Spine Using a Universal Entry Point: Clinical Validation.

STUDY DESIGN: Retrospective radiographic study. OBJECTIVE: To evaluate the accuracy of the free-hand placement of pedicle screws (PSs) using a new method of localization of entry points. SUMMARY OF BACKGROUND DATA: The PSs are essential in modern spinal surgery but their placement can be technically demanding. To improve this accuracy, numerous aids have been developed, some of them technologically advanced. Despite advances in technology the free-hand technique is still very popular. A simple geometric method of localization of entry points is proposed, designed to improved anatomic orientation. METHODS: The radiographic and clinical data of 92 consecutive patients who underwent primary placement of PS in the lumbar spine were retrospectively analyzed. Postoperative computed tomography scans were used to assess the accuracy of screw placement using both quantitative and anatomic criteria. RESULTS: A total of 85 patients with 410 screws were included in the study. Twenty screws were malpositioned, thus the overall accuracy was 95.12%. Of all levels instrumented the breach rate for the L1 level was highest (21.43%) and the difference was statistically significant. Two screws in 2 patients were symptomatic, causing radicular pain. Both underwent successful revisions. CONCLUSIONS: The proposed method of PS placement is safe and reliable for all levels from L2 to S1, with the accuracy similar to image-guided navigation systems.