Here we are, with the three studies selected for the July Microbiology Time:

• To explore the effects of surface characteristics on the deposition and persistence of touch DNA, Dr. Recipon and colleagues selected a range of substrates commonly found at crime scenes to be analyzed in vitro. The researchers discovered that these surface features influence cell deposition, morphology, retention, and the subsequent genetic analysis of touch DNA. Remarkably, while cell-derived fragments and fingermarks were detectable on various substrates for up to two months by targeting proteins and carbohydrates, swabbing and genetic analysis of mock traces yielded the most informative profiles primarily from substrates with the highest surface free energy. The researchers conclude that understanding the intrinsic properties of substrates is crucial for comprehending the transfer and persistence of biological traces, and appropriate methodologies and sampling devices are necessary for improving their detection and collection.
• The second study from the US assessed the performance of self-collected vaginal swabs for HPV detection using the Cobas 6800 system. The researchers found minimal variability in swabs self-collected by the same individual, as determined by the amplification of HPV and human β-globin control DNA, and high concordance between self-collected vaginal swabs and professional-collected cervical samples. The duration of dry storage did not affect HPV amplification; even the exposure of self-collected dry swabs to extreme summer and winter temperatures did not impact testing outcomes. These findings are another piece of evidence that suggests the use of self-collected vaginal samples for accurate clinical HPV testing, even after extreme temperature storage.
• To understand the impact of self-collection on HPV test outcomes, the authors of the third study selected and tested different swab collection workflows. What did they find? Depositing the collection swab into a resuspension buffer improved the PCR detection of human beta-hemoglobin compared to the “swirl-and-toss” method. Additionally, reducing the swab resuspension volume from 10 mL to 3 mL resulted in a PCR threshold reduction in the detection of human beta-globin. In a second step, the researchers performed a systematic literature search followed by data extraction and analysis to assess further the impact of resuspension volume on performance following self-collection. The article suggests that self-collection conditions can be optimized to improve sample recovery and performance, thereby enhancing cervical cancer screening.

Read the full studies: