False-negative severe acute respiratory syndrome coronavirus 2 test results can negatively impact the clinical and public health response to coronavirus disease 2019 (COVID-19). We used droplet digital polymerase chain reaction (ddPCR) to demonstrate that human DNA levels, a stable molecular marker of sampling quality, were significantly lower in samples from 40 confirmed or suspected COVID-19 cases that yielded negative diagnostic test results (ie, suspected false-negative test results) compared with a representative pool of 87 specimens submitted for COVID-19 testing. Our results support suboptimal biological sampling as a contributor to false-negative COVID-19 test results and underscore the importance of proper training and technique in the collection of nasopharyngeal specimens.

Due to global shortages of flocked nasopharyngeal swabs and appropriate viral transport media during the COVID-19 pandemic, alternate diagnostic specimens for SARS-CoV-2 detection are sought. The accuracy and feasibility of saliva samples collected and transported without specialized collection devices or media were evaluated. Saliva demonstrated good concordance with paired nasopharyngeal swabs for SARS-CoV-2 detection in 67/74 cases (90.5%), though barriers to saliva collection were observed in long-term care residents and outbreak settings. SARS-CoV-2 RNA was stable in human saliva at room temperature for up to 48 h after initial specimen collection, informing appropriate transport time and conditions.

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Nasopharyngeal swabs are critical to the diagnosis of respiratory infections including COVID-19, but collection techniques vary. We compared two recommended nasopharyngeal swab collection techniques in adult volunteers and found that swab rotation following nasopharyngeal contact did not recover additional nucleic acid (as measured by human DNA/RNA copy number). Rotation was also less tolerable for participants. Notably, both discomfort and nucleic acid recovery were significantly higher in Asians, consistent with nasal anatomy differences. Our results suggest that it is unnecessary to rotate the swab in place following contact with the nasopharynx, and reveal that procedural discomfort levels can differ by ethnicity.

Due to global shortages of flocked nasopharyngeal swabs and appropriate viral transport media during the COVID-19 pandemic, alternate diagnostic specimens for SARS-CoV-2 detection are sought. The accuracy and feasibility of saliva samples collected and transported without specialized collection devices or media were evaluated. Saliva demonstrated good concordance with paired nasopharyngeal swabs for SARS-CoV-2 detection in 67/74 cases (90.5%), though barriers to saliva collection were observed in long-term care residents and outbreak settings. SARS-CoV-2 RNA was stable in human saliva at room temperature for up to 48 hours after initial specimen collection, informing appropriate transport time and conditions.

Diagnosing latent tuberculosis (TB) infection (LTBI) in dialysis patients is complicated by poor response to tuberculin skin testing (TST), but the role of interferon-gamma release assays (IGRAs) in the dialysis population remains uncertain. Seventy-nine patients were recruited to compare conventional diagnosis (CD) with the results of two IGRA tests in a dialysis unit. Combining TST, chest x-ray and screening questionnaire results (ie, CD) identified 24 patients as possible LTBI. IGRA testing identified 22 (QuantiFERON Gold IT, Cellestis, USA) and 23 (T-spot.TB, Oxford Immunotec, United Kingdom) LTBI patients. IGRA and CD correlated moderately (κ=0.59). IGRA results correlated with history of TB, TB contact and birth in an endemic country. TST was not helpful in identifying LTBI patients in this population. The tendency for IGRAs to correlate with risk factors for TB, active TB infection and history of TB argues for their superiority over TST in dialysis patients. There was no superiority of one IGRA test over another.

pneumoniae isolates lack clonality, although some seemingly related clusters have been found. Plasmid analysis showed evidence of the spread of plasmids carrying carbapenemase-encoding genes between the examined isolates. Analysis of Enterobacter cloacae isolates revealed a more clonal nature of these CPOs in BC. The presence of related clusters provides evidence of interpatient organism transmission both within and between institutions. Although in our study, NDM-harboring E. cloacae isolates appeared to spread clonally, the spread of carbapenem resistance in K. pneumoniae seems to be plasmid mediated.