Multicenter study evaluating the Vitek MS system for identification of medically important yeasts

The optimal management of fungal infections is correlated with timely organism identification. Matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry (MS) is revolutionizing the identification of yeasts isolated from clinical specimens. We present a multicenter study assessing the performance of the Vitek MS system (bioMérieux) in identifying medically important yeasts. A collection of 852 isolates was tested, including 20 Candida species (626 isolates, including 58 C. albicans, 62 C. glabrata, and 53 C. krusei isolates), 35 Cryptococcus neoformans isolates, and 191 other clinically relevant yeast isolates; in total, 31 different species were evaluated. Isolates were directly applied to a target plate, followed by a formic acid overlay. Mass spectra were acquired using the Vitek MS system and were analyzed using the Vitek MS v2.0 database. The gold standard for identification was sequence analysis of the D2 region of the 26S rRNA gene. In total, 823 isolates (96.6%) were identified to the genus level and 819 isolates (96.1%) were identified to the species level. Twenty-four isolates (2.8%) were not identified, and five isolates (0.6%) were misidentified. Misidentified isolates included one isolate of C. albicans (n = 58) identified as Candida dubliniensis, one isolate of Candida parapsilosis (n = 73) identified as Candida pelliculosa, and three isolates of Geotrichum klebahnii (n = 6) identified as Geotrichum candidum. The identification of clinically relevant yeasts using MS is superior to the phenotypic identification systems currently employed in clinical microbiology laboratories

Associations between depressive symptoms and disease progression in older patients with chronic kidney disease: results of the EQUAL study

Background Depressive symptoms are associated with adverse clinical outcomes in patients with end-stage kidney disease; however, few small studies have examined this association in patients with earlier phases of chronic kidney disease (CKD). We studied associations between baseline depressive symptoms and clinical outcomes in older patients with advanced CKD and examined whether these associations differed depending on sex. Methods CKD patients (>= 65 years; estimated glomerular filtration rate <= 20 mL/min/1.73 m(2)) were included from a European multicentre prospective cohort between 2012 and 2019. Depressive symptoms were measured by the five-item Mental Health Inventory (cut-off <= 70; 0-100 scale). Cox proportional hazard analysis was used to study associations between depressive symptoms and time to dialysis initiation, all-cause mortality and these outcomes combined. A joint model was used to study the association between depressive symptoms and kidney function over time. Analyses were adjusted for potential baseline confounders. Results Overall kidney function decline in 1326 patients was -0.12 mL/min/1.73 m(2)/month. A total of 515 patients showed depressive symptoms. No significant association was found between depressive symptoms and kidney function over time (P = 0.08). Unlike women, men with depressive symptoms had an increased mortality rate compared with those without symptoms [adjusted hazard ratio 1.41 (95% confidence interval 1.03-1.93)]. Depressive symptoms were not significantly associated with a higher hazard of dialysis initiation, or with the combined outcome (i.e. dialysis initiation and all-cause mortality). Conclusions There was no significant association between depressive symptoms at baseline and decline in kidney function over time in older patients with advanced CKD. Depressive symptoms at baseline were associated with a higher mortality rate in men

False-Negative Results Obtained with the Gen-Probe Amplified Mycobacterium tuberculosis Direct Test Caused by Unrecognized Inhibition of the Amplification Reaction▿

The Gen-Probe Amplified Mycobacterium tuberculosis direct test is widely used in the diagnosis of tuberculosis. Specimens may contain amplification inhibitors, potentially leading to false-negative results if unrecognized. We report a failure to detect inhibition, despite adherence to the inhibition testing guidelines provided on the label, and recommend changes

Optimal Inoculation Methods and Quality Control for the NCCLS Oxacillin Agar Screen Test for Detection of Oxacillin Resistance in Staphylococcus aureus

To define more precisely the inoculation methods to be used in the oxacillin screen test for Staphylococcus aureus, we tested agar screen plates prepared in house with 6 μg of oxacillin/ml and 4% NaCl using the four different inoculation methods that would most likely be used by clinical laboratories. The organisms selected for testing were 19 heteroresistant mecA-producing strains and 41 non-mecA-producing strains for which oxacillin MICs were near the susceptible breakpoint. The inoculation method that was preferred by all four readers and that resulted in the best combination of sensitivity and specificity was a 1-μl loopful of a 0.5 McFarland suspension. A second objective of the study was to then use this method to inoculate plates from five different manufacturers of commercially prepared media. Although all commercial media performed with acceptable sensitivity compared to the reference lot, one of the commercial lots demonstrated a lack of specificity. Those lots of oxacillin screen medium that fail to grow heteroresistant strains can be detected by using S. aureus ATCC 43300 as a positive control in the test and by using transmitted light to carefully examine the plates for any growth. However, lack of specificity with commercial lots may be difficult to detect using any of the current quality control organisms

Multicenter Studies of Tigecycline Disk Diffusion Susceptibility Results for Acinetobacter spp.

Acinetobacter sp. isolates having multidrug resistance (MDR) patterns have become common in many medical centers worldwide, limiting therapeutic options. A five-center study tested 103 contemporary clinical Acinetobacter spp., including MDR strains, by reference broth microdilution and disk diffusion (15-μg disk content) methods against tigecycline. Applying U.S. Food and Drug Administration tigecycline breakpoint criteria for Enterobacteriaceae (susceptibility at ≤2 μg/ml [≤1 μg/ml by the European Committee on Antimicrobial Susceptibility Testing]; disk diffusion breakpoints at ≥19 mm and ≤14 mm) to Acinetobacter spp. led to an unacceptable error rate (23.3%). However, an adjustment of tigecycline disk diffusion breakpoints (susceptible/resistant) to ≥16/≤12 mm reduced intermethod errors to an acceptable level (only 9.7%, all minor)

New Delhi Metallo-β-Lactamase–producing Enterobacteriaceae, United States

We characterized 9 New Delhi metallo-β-lactamase–producing Enterobacteriaceae (5 Klebsiella pneumoniae, 2 Escherichia coli, 1 Enterobacter cloacae, 1 Salmonella enterica serovar Senftenberg) isolates identified in the United States and cultured from 8 patients in 5 states during April 2009–March 2011. Isolates were resistant to β-lactams, fluoroquinolones, and aminoglycosides, demonstrated MICs ≤1 µg/mL of colistin and polymyxin, and yielded positive metallo-β-lactamase screening results. Eight isolates had blaNDM-1, and 1 isolate had a novel allele (blaNDM-6). All 8 patients had recently been in India or Pakistan, where 6 received inpatient health care. Plasmids carrying blaNDM frequently carried AmpC or extended spectrum β-lactamase genes. Two K. pneumoniae isolates and a K. pneumoniae isolate from Sweden shared incompatibility group A/C plasmids with indistinguishable restriction patterns and a common blaNDM fragment; all 3 were multilocus sequence type 14. Restriction profiles of the remaining New Delhi metallo-β-lactamase plasmids, including 2 from the same patient, were diverse