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Detection of Bordetella pertussis and Bordetella parapertussis using molecular methods is sensitive and specific with a short turnaround time compared to other diagnostic methods. In this multicenter study, we compared the performance of the Simplexa Bordetella Direct kit to those of other molecular assays in detecting and differentiating B. pertussis and B. parapertussis in nasopharyngeal swab specimens. The limits of detection (LODs) were 150 CFU/ml or 3 fg/μl of DNA for B. pertussis and 1,500 CFU/ml or 10 fg/μl of DNA for B. parapertussis. A total of 1,103 fresh and residual frozen specimens from eight clinical sites were tested. Combining the data from individual clinical sites using different comparative assays, the overall positive percent agreement (PPA) and negative percent agreement (NPA) for B. pertussis were 98.7% and 97.3%, respectively. The overall PPA and NPA for B. parapertussis were 96.7% and 100%, respectively. For prospective fresh specimens, the overall PPA and NPA for both targets were 97.7% and 99.3%, respectively. For retrospective frozen specimens, the overall PPA and NPA for both targets were 92.6% and 93.2%, respectively. The percentage of invalid results was 1.0%. A cross-reactivity study using 74 non-Bordetella bacterial species and five yeast species revealed that the Simplexa Bordetella Direct kit was 100% specific. The hands-on time and assay run time of the Simplexa Bordetella Direct kit are favorable compared to those of other commercial and laboratory-developed tests. In summary, the Simplexa Bordetella Direct kit has a performance comparable to those of other molecular assays for the detection of B. pertussis and B. parapertussis.

Colistin and polymyxin B MICs were determined for 106 carbapenem-resistant Klebsiella pneumoniae (CR-Kp) isolates using Sensititre Research Use Only GNX2F plates (Thermo Fisher) and compared to CLSI broth macrodilution (BMD) as the reference method. For colistin, EUCAST breakpoints were applied and testing of isolates with very major (VM) errors was repeated in duplicate by both methods to determine a majority result. Essential agreement (MIC ± one dilution) of GNX2F with the reference method was 97.1% for polymyxin B and 92.5% for colistin (7 VM errors, 22.6%). After discrepancy testing, there were 28 colistin resistant isolates by BMD and essential agreement was 94.3% with 4 VM errors (14.3%). Colistin and polymyxin B GNX2F results showed acceptable essential agreement with BMD for MICS without interpretation. Colistin VM errors with EUCAST breakpoints were due to MIC variability in the 2 to 4 μg/mL range that could be addressed by establishing an intermediate category.

Molecular tests to diagnose conditions involving the disruption of normal microbiota are difficult to optimize. Using Nugent-scored Gram stain (NS) as the reference standard, we evaluated the performance of 3 molecular assays for the diagnosis of bacterial vaginosis (BV) and examined the impact of an incremental increase in bacterial targets. The BD Affirm assay includes a DNA probe for Gardnerella vaginalis, the Hologic transcription-mediated amplification (TMA) analyte-specific reagent (ASR) assay adds a second Lactobacillus sp. target, and the recently cleared in vitro diagnostic use (IVD) Aptima BV assay includes a third target (Atopobium vaginae). The diagnosis of vulvovaginal candidiasis (VVC) by the Affirm and Candida vaginitis Hologic TMA ASR assays was assessed using microscopy for yeast as the reference standard. From May to December 2018, 111 women with vaginitis symptoms prompting the clinician to order an Affirm test were enrolled with informed consent for the collection of additional specimens. Clinicians accurately predicted BV as the most likely diagnosis for 71% of the 45 patients with BV. Coinfection occurred in 13.5% of patients. For BV, the specificity of the Aptima IVD assay (86.3%) was higher than the Affirm assay (60.6%, P = 0.0002), but sensitivities were not significantly different. For VVC, the sensitivity of the ASR assay (100%) was higher than Affirm (75.9%; P = 0.023) and the specificity of the Affirm assay (98.8%) was higher than the ASR assay (86.6%; P = 0.004).

Reducing airborne bioburden in total joint arthroplasty (TJA) is of critical importance. The efficacy of crystalline ultraviolet-C (C-UVC) filtration in reducing bioburden in a dynamic operating room (OR) environment has not been evaluated. We assessed whether C-UVC filtration reduced (i) total particle counts (TPC); (ii) viable particle counts (VPC); and (iii) colony-forming units (CFUs). Fifty primary TJA cases were performed in a positive-pressure OR; 25 cases with the C-UVC unit and 25 cases without. The air was sampled by a particle counter and an impact air sampler to measure particle counts and CFUs, respectively. To compare TPC, VPC, and CFU/m3 between groups, independent t tests and multivariate regression, adjusted for number of OR staff and door openings, were performed. The C-UVC group had significantly lower TPC (2.6 × 106 vs. 4.7 × 106 particles, p = 0.001) and VPC (18,605 vs. 27,516 particles, p = 0.001). There were fewer CFUs in the C-UVC group (10.9 CFU/m3 vs. 13.7 CFU/m3 , p = 0.163). Multivariate analysis identified C-UVC filtration as a significant predictor of decreased TPC (β = -0.44, p = 0.002) and VPC (β = -0.47, p = 0.001) after accounting for door openings and number of OR staff. The reduction in CFUs was not significant on multivariate analysis. In this prospective pilot study, a C-UVC air disinfection and recirculation unit led to a significant reduction in both TPC and VPC and a non-significant reduction in CFU. Statement of clinical significance: Further studies are needed to investigate the effects of C-UVC filtration units on surgical-site infection rates. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:431-437, 2020.

Background Daptomycin (DAP) is a lipopeptide antibiotic and is first-line treatment for infections caused by Vancomycin-resistant Enterococcus (VRE). DAP is considered a safe antimicrobial agent, most commonly causing elevation of CPK. The historical incidence of DAP toxicity reported in the literature is low, ranging between 3 to 9%. We aim to describe the incidence of DAP toxicity among patients with VRE blood stream infection (BSI). Methods This is a retrospective cohort study conducted in a tertiary hospital in Cleveland, Ohio. We included all consecutive adult patients diagnosed with VRE BSI treated with DAP between November 2011 and January 2015. Patients were grouped based on dose of DAP received (Group 1: ≤6 mg/kg and Group 2 ≥ 8 mg/kg). Patient data were obtained from the microbiology department database, pharmacy information technology services and electronic medical records (EMR) (Table 1). Results During the study period, a total of 217 patients with VRE BSI were treated with DAP. (Table 1) The number of patients that received DAP dose of ≤6 mg/kg was 192 (88%), compared with 25 patients that received a DAP dose of ≥8 mg/kg (12%). The total incidence of DAP toxicity was present in only 3 patients (1.4%); and of those, only 2 patients developed CPK elevation leading to rhabdomyolysis requiring discontinuation of DAP (Maximum CPK value was 3142 U/L and 987 U/L for each case). The other patient developed a rash thought to be secondary to DAP. Of note, all 3 patients that developed DAP toxicity, received doses of ≤6 mg/kg. Conclusion In this retrospective cohort study of patients with VRE BSI treated with DAP, the incidence of DAP toxicity was only 3 cases out of 217 patients. All of these patients received doses of ≤6 mg/kg of DAP. This is lower than what is reported in the literature. DAP was well tolerated and the development of side effects did not seem to be related to the dose. Disclosures S. S. Richter, bioMerieux: Grant Investigator, Research grant. BD Diagnostics: Grant Investigator, Research grant. Roche: Grant Investigator, Research grant. Hologic: Grant Investigator, Research grant. Diasorin: Grant Investigator, Research grant. Accelerate: Grant Investigator, Research grant. Biofire: Grant Investigator, Research grant.

Background Pertussis is a vaccine preventable disease caused by Bordetella pertussis with highest mortality observed in infants. Rapid diagnosis allows prompt treatment and administration of prophylaxis to those at high risk of severe disease. Molecular assays are commonly used for diagnosis because of the long turn-around time and reduced sensitivity associated with culture of samples obtained >2 weeks after symptom onset. We compared the workflow and performance of two molecular assays for the detection of B. pertussis from nasopharyngeal (NP) swab specimens. Methods NP swabs in universal transport media submitted to Cleveland Clinic for B. pertussis testing are routinely tested by the AmpliVue Bordetella assay (Quidel). The AmpliVue utilizes helicase-dependent amplification targeting the insertion sequence IS481 and detection in a lateral flow device. Remnant specimens (n = 112) were stored at -70° C until IRB approval was obtained for this study. The Simplexa™ Bordetella Direct PCR assay (DiaSorin Molecular) targeting IS481 for detection of B. pertussis and IS1001 for identification of Bordetella parapertussis was performed on the LIAISON MDx instrument. The Simplexa and AmpliVue results were compared. To arbitrate discordant B. pertussis results or positive results for B. parapertussis (not included in the AmpliVue assay), samples were sent to DiaSorin for sequencing. Sensitivity and specificity were determined for each assay’s detection of B. pertussis based on sequencing as the reference method for discordant samples. Results Positive results for B. pertussis were detected for 14 specimens by AmpliVue and 18 specimens by Simplexa. Discrepancy analysis by sequencing confirmed 4 B. pertussis positive specimens detected only by Simplexa and one false-positive result for each assay. The sensitivities of AmpliVue and Simplexa were 76.5% and 100%, respectively. The specificity of both assays was 98.9%. Positivity rates were 27% for 48 children ≥1 year, 4% for 25 infants, and 8% for 39 adults tested. The Simplexa B. parapertussis target detected in one child’s specimen was confirmed by sequencing. Conclusion Compared with AmpliVue, the Simplexa assay required less hands on time and provided detection of more specimens containing B. pertussis. Disclosures S. S. Richter, bioMerieux: Grant Investigator, Research grant. BD Diagnostics: Grant Investigator, Research grant. Roche: Grant Investigator, Research grant. Hologic: Grant Investigator, Research grant. Diasorin: Grant Investigator, Research grant. Accelerate: Grant Investigator, Research grant. Biofire: Grant Investigator, Research grant.

Background Helicobacter pylori is associated with peptic ulcer disease and gastric malignancy. Antimicrobial susceptibility testing (AST) is often requested for patients who fail eradication therapy. The CLSI reference method, agar dilution (AD), is not performed in most laboratories and maintaining organism viability during transit to a reference laboratory is difficult. We assessed the performance of the Etest (bioMerieux) as a method for H. pylori AST in comparison to AD. Methods Frozen stocks of 82 H. pylori isolates with AD results previously reported by Mayo Clinic were prepared from the same plate for distribution to participating laboratories. Etest was performed at ARUP Laboratories and Cleveland Clinic (CC). For Etest, isolates were incubated for 72 hours in a microaerobic atmosphere. Aged Mueller–Hinton agar with 5% sheep blood plates were inoculated with a three McFarland suspension prepared in brain heart infusion broth. Etest strips were applied and MICs read after 72 hours of microaerobic incubation. Results were interpreted by applying CLSI and EUCAST breakpoints. Categorical agreement (CA), very major, major and minor errors (VME, ME, and mE) were determined for Etest using AD as the reference method. Isolates with errors were repeat tested in duplicate by Etest to determine the final results summarized below. Results For clarithromycin, 65% of isolates were resistant (R) by AD; Etest results at each laboratory showed 97.5% CA (1 mE and 1 ME). For tetracycline, only 2.5% of isolates were R by AD; a single VME occurred at both ARUP and CC (98.8% CA) with the same isolate. The AD dilutions tested for amoxicillin prevented interpretation with EUCAST breakpoints. With one exception, amoxicillin Etest results were susceptible (S, ≤0.125 mg/L) at both laboratories (98.8% of MICs ± one dilution). Applying levofloxacin EUCAST breakpoints (S, ≤1 mg/L) to interpret ciprofloxacin results, 57.8% of isolates were R by AD. ARUP CA was 97.5% (1 ME, 1 VME) and CC CA was 96.3% (1 ME, 2 VMEs). Conclusion Clarithromycin, tetracycline, and ciprofloxacin Etest results for H. pylori showed acceptable CA (>95%) at both testing sites compared with the AD reference method. The comparative ease of performance and reproducibility of the Etest may help standardize it as an AST method for H. pylori. Disclosures S. S. Richter, bioMerieux: Grant Investigator, Research grant; BD Diagnostics: Grant Investigator, Research grant; Roche: Grant Investigator, Research grant; Hologic: Grant Investigator, Research grant; Diasorin: Grant Investigator, Research grant; Accelerate: Grant Investigator, Research grant; Biofire: Grant Investigator, Research grant.

Background Reports of poor outcomes in patients (patients) infected with VRE strains with daptomycin (DAP) minimum inhibitory concentrations (MIC) near the susceptible breakpoint (