ABSTRACT
Clostridium difficile is the most common and important cause of toxigenic colitis in the health care setting. Laboratory diagnostics have included bacterial culture with further identification of toxigenic stains, or more commonly, direct detection of preformed toxin in stool samples using biological or immunochemistry assays. Recently, molecular amplification assays for the direct detection of toxin-encoding genes have become available commercially. We prospectively evaluated 2 FDA-cleared molecular amplification tests, the Illumigene C. difficile and the ProGastro Cd PCR assay, for the direct detection of toxigenic C. difficile from fecal samples. Of 446 samples tested, 418 produced matching amplification results, 88 positive and 330 negative, and 13 resolved with repeat testing. Toxigenic culture and direct cytotoxin testing were used to resolve the remaining 15 discordant samples. Overall, each assay performed well and correctly identified 97% of positive samples.
Subject(s)
Bacteriological Techniques/methods , Clostridioides difficile/isolation & purification , Clostridium Infections/diagnosis , Feces/microbiology , Molecular Diagnostic Techniques/methods , Nucleic Acid Amplification Techniques/methods , Clostridioides difficile/genetics , Clostridium Infections/microbiology , Humans , Prospective Studies , Sensitivity and SpecificityABSTRACT
Enzyme immunoassays are currently the most common tests used in the clinical laboratory for the detection of Clostridium difficile toxins; however, significant problems with their performance have recently been described. We prospectively reevaluated the Meridian Premier C. difficile toxin A/B assay with direct comparison to a 2-step algorithm that screened for C. difficile common antigen and compared cytotoxin and real-time polymerase chain reaction (PCR) as confirmatory procedures. The Premier assay lacked sufficient sensitivity, missing 25% of true-positive samples. PCR was the most sensitive method and the only procedure that allowed same day testing and reporting.
Subject(s)
Bacterial Proteins/analysis , Bacterial Toxins/analysis , Clostridioides difficile/isolation & purification , Cytotoxins/toxicity , Enterotoxins/analysis , Glutamate Dehydrogenase/analysis , Immunoassay/methods , Polymerase Chain Reaction/methods , Bacterial Proteins/genetics , Bacterial Proteins/immunology , Bacterial Proteins/toxicity , Bacterial Toxins/genetics , Bacterial Toxins/immunology , Bacterial Toxins/toxicity , Clostridioides difficile/genetics , Clostridioides difficile/immunology , Clostridium Infections/microbiology , Colitis/microbiology , Enterotoxins/genetics , Enterotoxins/immunology , Enterotoxins/toxicity , Glutamate Dehydrogenase/genetics , Glutamate Dehydrogenase/immunology , Humans , Prospective Studies , Sensitivity and SpecificityABSTRACT
In a prospective study, the Gen-Probe PACE 2 (GP) assay was compared with Abbott Laboratories' ligase chain reaction (LCR) assay for the detection of Chlamydia trachomatis. A total of 493 female patients consented to collection of two cervical samples; a first-void urine (FVU) sample was collected also from 446 of the participants. Cervical samples were tested by both GP and LCR; 16 samples (3.1%) tested positive by both methods and no discrepant results were observed. All but one of the FVU samples collected from patients with a positive cervical sample was positive for C. trachomatis by LCR. The stability of FVU samples over time in the LCR test was also evaluated and proved to be significantly longer than the 4 days stated by the manufacturer. While LCR proved to be highly sensitive in detecting chlamydial infection in FVU samples, no difference was noted between LCR and GP in the detection of cervical C. trachomatis infection in this study population.
