Bact alert 3d microbial detection system

The blood samples for DNI measurement were transferred to the laboratory department in ethylenediaminetetraacetic acid (EDTA) tubes. The DNI was determined within 1 h of blood sampling.
The DNI is included as part of the routine complete blood count (CBS) test at our hospital. The DNI was calculated using an automatic cell analyzer (ADVIA 2120 Hematology System, Siemens Healthcare Diagnostics, Forchheim, Germany) [10 (link)]. This cell analyzer counts white blood cells (WBCs) in independent myeloperoxidase (MPO) and nuclear lobularity channels. The formula for calculating DNI is as follows: DNI (%) = (neutrophil and eosinophil subfractions measured in the MPO channel by a cytochemical MPO reaction)-(polymorphonuclear neutrophil [PMN] subfraction measured in the nuclear lobularity channel by a reflected light beam). Blood cultures were ordered at the discretion of the primary physician based on the presence of the signs and symptoms of SIRS. Each set of blood samples was inoculated into one aerobic and anaerobic bottle and immediately loaded into a BacT/ALERT 3D Microbial Detection System (bioMerieux, Inc., Durham, NC, USA). Candida species identification was done using the automated Vitek 2 Yeast Biochemical Card (bioMerieux, Inc.).

Acute and convalescent serum samples were sent to the US Centers for Disease Control and Prevention (CDC) for serologic analysis for brucellosis by microscopic agglutination test (MAT) using standardized Brucella abortus strain 1119-3 killed antigen (National Veterinary Services Laboratory [NVSL], Ames, IA, USA) at a 1:25 working dilution. Samples were inoculated into U-bottom plates and incubated at 26°C. High-positive, low-positive and negative control sera (NVSL) were also included for each test run. Results were read on a Scienceware Plate Reader (Bel-Art Products, Wayne, NJ, USA). Inoculated blood culture bottles were loaded into the BacT/ALERT 3D Microbial Detection System (bioMerieux, Marcy l’Etoile, France), where they were incubated for 5 days.^{15 (link),16 (link)} Cases were defined by a 4-fold or greater increase in the B. abortus MAT antibody titre between acute and convalescent serum or by isolation of Brucella spp. from blood cultures.¹⁷

Blood and throat swab cultures are routinely performed in infants admitted to the neonatal intensive care unit (NICU) with suspected sepsis or pneumonia. Cerebrospinal fluid (CSF) and other specimen cultures are performed in infants with suspected meningitis or other clinical manifestations. GBS was isolated from blood samples using the BACT/ALERT 3D microbial detection system (bio-Mérieux, Marcy-l’Étoile, France). Positive blood culture bottles were subsequently sub cultured to Columbia blood agar (bio-Mérieux, Marcy-l’Étoile, France) incubated aerobically at 35 °C under 5–10% CO₂ and observed for colony growth for 48 h. CSF samples were inoculated into 3D blood culture bottles and immediate Gram stain was performed. Other swabs such as eye swab and umbilical exudation swab were plated onto Columbia blood agar plates that were incubated at 35 °C for 18–24 h under 5–10% CO₂ and examined for growth of ß-haemolytic GBS-like colony morphology. Presumptive identification of GBS was based on Gram stain and a positive CAMP test, determined by an arrowhead-shaped zone of complete haemolysis. Vitek 2 COMPACT (bio-Mérieux, Marcy-l’Étoile, France) was used to perform identification and susceptibility testing.