The risk factors for development of paradoxical response were studied in a cohort of 104 patients with culture-documented Mycobacterium tuberculosis infection. Paradoxical deterioration occurred in 16 (15.4%) patients (case group) during antituberculosis therapy, involving lungs and pleura (n=4), spine and paraspinal tissue (n=5), intracranium (n=3), peritoneum (n=2), bone and joint (n=1), and lymph node (n=1). The median time from commencement of treatment to paradoxical deterioration was 56 days (range, 20-109 days). Compared with 53 patients without clinical deterioration after antituberculosis therapy (control group), patients with paradoxical response were more likely to have extrapulmonary involvement (62.5% vs. 17.0%; P<0.05) at initial diagnosis, to have lower baseline lymphocyte counts (672+/-315 cells/microl vs. 1,328+/-467 cells/microl; P<0.001), and to exhibit a greater surge in lymphocyte counts (627+/-465 cells/microl vs. 225+/-216 cells/microl; P<0.05) during paradoxical response. Further studies on lymphocyte subsets and cytokine levels would be useful in understanding the exact immunological mechanisms involved in immunorestitution.

. Overall, the Biotyper system generated significantly more accurate identifications than the Vitek MS IVD system (P ‫؍‬ 0.016; 177 versus 167 out of 181 specimens). The Biotyper system identified the minority species among polymicrobial blood cultures. We also compared the performance of an in-house extraction method with that of the Sepsityper on both MALDI-TOF MS systems. The in-house method generated more correct identifications at the genus level than the Sepsityper (96.7% versus 93.5%) on the Biotyper system, whereas the two methods exhibited the same performance level (88.0% versus 88.0%) on the Vitek MS IVD system. Our study confirmed the practical advantages of MALDI-TOF MS, and our in-house extraction method reduced the reagent cost to $1 per specimen, with a shorter turnaround time of 3 h, which is highly cost-effective for a diagnostic microbiology service. Bloodstream infection is a condition associated with high morbidity and mortality (1, 2). The rapid identification of bloodstream pathogens is critical to clinical management and the choice of appropriate antibiotic treatments (3, 4). Currently, microbiologic diagnosis of bacteremia relies on subculture of positive blood culture broths on solid medium for an 18-to 24-h incubation period followed by biochemical tests or an automated preformed enzyme assay for identification of the bacteria (5). In general, laboratory diagnosis of common pathogens requires 18 to 48 h, while diagnosis of fastidious organisms requires longer incubation and identification procedures. Although the use of modern techniques such as fluorescence in situ hybridization and PCR can shorten the identification time (6), these operations require specialized equipment and technical expertise and the targeted pathogens are limited in a single run (7). Therefore, the introduction of a simple, rapid, broad-spectrum, and cost-effective system for the identification of blood culture pathogens is imperative.Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was developed in the 1980s, and this technique had been widely used for biomolecule analysis in the chemical industry for over 10 years. In recent years, MALDI-TOF MS was introduced for bacterial identification, which revolutionized the diagnostic microbiology service (8). Two manufacturers, bioMérieux (Marcy l'Etoile, France) and Bruker Daltonics (Bremen, Germany), are marketing efficient MALDI-TOF systems, the Vitek-MS and the Microflex LT, respectively, that allow the identification of bacteria and yeasts in a few minutes instead of the hours required by traditional methods. The practical use of MALDI-TOF MS for microorganism identification directly from positive blood culture specimens has been substantiated by a number of studies (9-13). Generally, studies have shown high identification rates for various types of organisms with the use of MALDI-TOF MS . However, various organism isolation methods from blood were used in those studies and therefore method standardization is necessary. The...

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