Performance Evaluation of a New Culture Colorimetric Detection Assay.

OBJECTIVE: To evaluate the performance of the culture colorimetric detection assay MYCO WELL D-ONE® (MWD-ONE), designed to detect sexually transmitted infections using real-time polymerase chain reaction (PCR) as a reference method. MATERIALS AND METHODS: One hundred and ten urogenital samples were screened for Gardnerella vaginalis (GV), Trichomonas vaginalis (TV), Mycoplasma hominis (MH), Mycoplasma spp., and Ureaplasma urealyticum (UU)/Ureaplasma parvum (UP) using the MWD-ONE and real-time PCR assays Gardnerella vaginalis/Lactobacillus species Real-TM Quant and Anyplex II STI-7 Detection, respectively. RESULTS: GV was detected in 33 samples by both the MWD-ONE and real-time PCR, while 6 samples gave discordant results. TV was detected by both MWD-ONE and Anyplex II STI-7 Detection kits in 3 samples, while 107 were negative. MH was detected by both methods in 5 cases, 4 samples gave discordant results, and 101 were negative. Mycoplasma genitalium (MG) was detected by Anyplex II STI-7 in 2 cases, 1 of which was detected as Mycoplasma spp. by MWD-ONE. Ten samples were positive by MWD-ONE, and 98 were negative with both assays. With regard to UU/UP, 24 cases were detected by MWD-ONE and Anyplex PCR, 25 by PCR only, 4 by MWD-ONE, and 57 tested negative with both methods.The positive predictive values (PPV) and negative predictive values (NPV) of the MWD-ONE assay for the pathogens tested were as following: GV, PPV 94.3%, NPV 94.7%; TV, PPV and NPV 100%; MH, PPV 71.4%, NPV 98.1%; Mycoplasma spp., PPV 9.1%, NPV 98.9%; and Ureaplasma spp., PPV 85.7 %, NPV 69.5 %. The agreement between the MWD-ONE and PCR was strong for GV and MH (k=0.8 and 0.7, respectively); perfect for TV (k=1); and moderate for UU/UP (k=0.4). CONCLUSION: MWD-ONE assay appears to be suitable for routine testing of sexually transmitted infections.

Rapid and cost-effective identification and antimicrobial susceptibility testing in patients with Gram-negative bacteremia directly from blood-culture fluid.

Rapid pathogen identification (ID) and antimicrobial susceptibility testing (AST) in bacteremia cases or sepsis could improve patient prognosis. Thus, it is important to provide timely reports, which make it possible for clinicians to set up appropriate antibiotic therapy during the early stages of bloodstream infection (BSI). This study evaluates an in-house microbiological protocol for early ID as well as AST on Gram negative bacteria directly from positive monomicrobial and polymicrobial blood cultures (BCs). A total of 102 non-duplicated positive BCs from patients with Gram-negative bacteremia were tested. Both IDs and ASTs were performed from bacterial pellets extracted directly from BCs using our protocol, which was applied through the combined use of a MALDI-TOF MS and Vitek2 automated system. The results of our study showed a 100% agreement in bacterial ID and 98.25% categorical agreement in AST when compared to those obtained by routine conventional methods. We recorded only a 0.76% minor error (mE), 0.76% major error (ME) and a 0.20% very major error (VME). Moreover, the turnaround time (TAT) regarding the final AST report was significantly shortened (ΔTAT = 8-20 h, p < 0.00001). This in-house protocol is rapid, easy to perform and cost effective and could be successfully introduced into any clinical microbiology laboratory. A final same-day report of ID and AST improves patient management, by early and appropriate antimicrobial treatment and could potentially optimize antimicrobial stewardship programs.

Screening of respiratory pathogens by Respiratory Multi Well System (MWS) r-gene™ assay in hospitalized patients.

Novel respiratory viruses have been identified as possible agents of upper and lower respiratory tract infections. Multiplex real-time PCRs have been developed to identify clinically relevant respiratory pathogens. In this study, 178 respiratory samples already screened for influenza virus types A and B by Flu A/B ASR real-time PCR kit were retrospectively analyzed with the Respiratory Multi Well System (MWS) r-gene™ real-time PCR kit which detects a wide spectrum of respiratory pathogens. The goal was to demonstrate the importance of a wide spectrum screening compared to a single diagnostic request. The Flu A/B ASR kit detected influenza B virus in 1.7% of the samples (3/178) and no influenza A virus. The MWS r-gene™ kit detected influenza virus in 6.7% (12/178) of samples (0.6% influenza A, and 6.2% influenza B), while the overall detection rate for respiratory pathogens was 54% (96/178). Co-infections were detected in 8/178 (4.5%) samples. Adenovirus was the infectious agent detected most frequently, followed by respiratory syncytial virus. The risk of being infected by respiratory syncytial virus is almost threefold higher in patients older than 65 years compared to the younger age group (OR:2.7, 95% CI: 1.2-6.2). Wide spectrum screening of respiratory pathogens by real-time PCR is an effective means of detecting clinically relevant viral pathogens.