Multicenter Evaluation of the Implementation Status of Laboratory Tests in Korea and the Potential Usefulness of a Multiplex PCR Assay in Patients with Suspected Central Nervous System Infections.

BACKGROUND: The rapid diagnosis and treatment of central nervous system (CNS) infections are critical to minimizing morbidity and mortality. We evaluated the implementation status of laboratory tests in patients with suspected CNS infection, and the potential usefulness of a multiplex PCR assay for rapid and simultaneous detection in cerebrospinal fluid (CSF) of 14 targets capable of causing CNS infections. METHODS: The study was conducted at 5 hospitals located in Daegu and Gyeongju over a period of 6 months. A total of 140 patients with suspected CNS infection were included. CSF samples were tested for 6 bacteria, 7 viruses, and 1 yeast using multiplex PCR (FilmArray Meningitis/Encephalitis Panel, BioFire Diagnostics/Biomerieux, Salt Lake City, UT, USA) and conventional diagnostic testing including chemistry tests, cell count, bacterial culture, antigen detection assay, and pathogen-specific PCR. RESULTS: The five conventional tests most commonly performed were the chemistry and cell count (100%), bacterial culture (94.3%), enterovirus PCR (52.9%), and herpes simplex virus PCR (25.7%). Among the 140 CSF samples, 27 (19.3%) and 42 (30.0%) tested positive by conventional and the FilmArray ME panel testing, respectively. CONCLUSIONS: The detection rate of pathogens for CNS infections increased using only one FilmArray test compared to all of the conventional methods actually performed in patients with suspected CNS infection.

Myeloperoxidase Deficiency Manifesting as Pseudoneutropenia with Low Mean Peroxidase Index and High Monocyte Count in 4 Adult Patients.

Myeloperoxidase (MPO) deficiency, one of the most common inherited phagocyte defects, and may exist as a transient phenomenon in combination with some clinical condition. Hematological analyzer ADVIA 2120i is used to identify the different types of leukocytes based on their size and staining properties, and by mean peroxidase index (MPXI). When MPO deficiency is present, neutrophils may be incorrectly counted as monocytes with lower MPXI values. We encountered a few cases of MPO deficiency with abnormally high monocytes counts resulting in pseudoneutropenia. These abnormal reports could lead to a mistaken diagnosis of severe neutropenia, which could result in unnecessary therapy. Manual differential count exhibited the normal differential count in every case. Every case yielded a markedly low MPXI value below -20. In conclusion, we suggest that MPO deficiency must be considered in patients especially when abnormally high monocyte counts combined with low MPXI values are observed.