ABSTRACT
Various commercial assays have recently been developed for detecting glutamate dehydrogenase (GDH) and/or toxin A/B to diagnose Clostridioides difficile infection (CDI). We compared the performance of two assays for the simultaneous detection of C. difficile GDH and toxin A/B, using 150 stool samples: C. DIFF QUIK CHEK COMPLETE (QCC; TechLab, Blacksburg, VA, USA) and RIDASCREEN Clostridium difficile GDH (RC-GDH) and Toxin A/B (RC-Toxin A/B; R-Biopharm, Darmstadt, Germany). For GDH detection, QCC and RC-GDH showed satisfactory sensitivity (95.7% and 94.3%, respectively) and specificity (92.5% and 93.8%, respectively) compared with C. difficile culture. For toxin A/B detection, QCC showed higher sensitivity than RC-Toxin A/B (60.0% vs 33.3%, P < 0.001) compared with toxigenic C. difficile culture. When the results of QCC or RC-GDH+RC-Toxin A/B were used as the first step of a two-step algorithm for diagnosing CDI, QCC permitted more accurate discrimination than RC of positive or negative results for CDI (77.3% and 65.3%, respectively). QCC is useful for the simultaneous detection of C. difficile GDH and toxin A/B as a part of the two-step algorithm for diagnosing CDI.
Subject(s)
Clostridioides difficile , Discrimination, Psychological , Glutamate Dehydrogenase , Glutamic Acid , Sensitivity and SpecificityABSTRACT
Actinotignum schaalii is an emerging uropathogen; however, routine culture protocols and usual phenotypic methods do not allow for easy detection and identification. Herein, we report the first Korean case of urinary tract infection caused by A. schaalii in a 79-year-old patient with prostate cancer. A gram-positive rod bacterium was isolated from the patient's urine after 2 days of culture and identified as A. schaalii using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry and DNA target sequencing.
Subject(s)
Aged , Humans , DNA , Mass Spectrometry , Prostatic Neoplasms , Urinary Tract Infections , Urinary TractABSTRACT
We describe the laboratory identification of Leptotrichia species from clinical isolates collected over a six-year period. Five isolates from blood cultures were identified as Leptotrichia species. Gram stain showed large, fusiform, gram-negative or -variable bacilli. Identification based on biochemical testing was unsuccessful; however, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry proved to be a useful tool for identifying Leptotrichia species to the genus level. Species level identification was successfully achieved by using 16S ribosomal RNA gene sequencing.
Subject(s)
Humans , Bacteremia , Leptotrichia , Mass Spectrometry , RNA, Ribosomal, 16SABSTRACT
Annual proficiency surveys were conducted in March, June, and September in 2015 by the Clinical Microbiology Subcommittee of the Korean Association of External Quality Assessment Service. The program covers the sections of bacteriology, advanced bacteriology and mycology, mycobacteriology, and parasitology. Each trial was composed of three sets of different combinations of five bacteria and yeasts. These sets were distributed among laboratories for Gram staining, culture, identification, and antimicrobial susceptibility tests. Five slides with fixed sputum smears were provided as part of each trial for acid-fast bacilli detection. The survey material distribution was section-based. Two survey materials were provided in each trial, while five specimens for mycobacterial culture and identification, five specimens for anti-tuberculosis susceptibility testing and two Mycobacterium tuberculosis strains for rapid detection of rifampin and isoniazid resistance were distributed in the March and June trials. Five virtual microscopy files for stool parasite examination were availed by registered participants in the June trial. Out of the 334 enrolled laboratories, 328 (98.2%), 328 (98.2%), and 329 (98.5%) submitted responses in trials I, II, and III, respectively. Identification of bacteria, namely, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Streptococcus pneumoniae, and Vibrio fluvialis by more than 95% of participants was acceptable. Surveillance cultures for vancomycin-resistant enterococci and carbapenem-resistant Enterobacteriaceae were determined accurately by 75.8%–85.3% and 93.1% of the respondents, respectively. Species-level identification of Candida krusei, Candida lusitanae, and Candida guilliermondii was still low at 79.8%, 55.7%, and 42.7%, respectively. Disk diffusion method revealed an unacceptably high false-positive rate of resistance to glycopeptides in E. faecalis and to trimethoprim-sulfamethoxazole in S. pneumoniae. Advanced bacteriology trials revealed unsatisfactory results for species-level identification of moulds. Mycobacterial culture, identification and susceptibility testing, and molecular detection of rifampin and isoniazid resistance were performed exceedingly well by participants. Hymenolepsis diminuta could not be identified by participants, with a correct answer rate of only 46.5% and ‘no parasite seen’ answer rate of only 31.8% for negative specimens. Species-level identification of Candida and moulds was challenging for clinical microbiology laboratories. Disk diffusion method was found to be problematic in testing the susceptibility of microorganisms to glycopeptides and trimethoprim-sulfamethoxazole. Improvement is required in result interpretation of negative specimens in parasitology.