Background: Recent publications from a single research group have suggested that aldehyde-based high-level disinfectants (HLDs), such as ortho-phthalaldehyde (OPA), are not effective at inactivating HPVs and that therefore, patients may be at risk of HPV infection from medical devices. These results could have significant public health consequences and therefore necessitated evaluation of their reproducibility and clinical relevance.
Methods: We developed methods and used standardised controls to: (1) quantify the infectious levels of clinically-sourced HPVs from patient lesions and compare them to laboratory-derived HPVs, (2) evaluate experimental factors that should be controlled to ensure consistent and reproducible infectivity measurements of different HPV genotypes, and (3) determine the efficacy of select HLDs.
Findings: A novel focus forming unit (FFU) infectivity assay demonstrated that exfoliates from patient anogenital lesions and respiratory papillomas yielded infectious HPV burdens up to 2.7 × 103 FFU; therefore, using 2.2 × 102 to 1.0 × 104 FFU of laboratory-derived HPVs in disinfection assays provides a relevant range for clinical exposures. RNase and neutralising antibody sensitivities were used to ensure valid infectivity measures of tissue-derived and recombinant HPV preparations. HPV infectivity was demonstrated over a dynamic range of 4-5 log10; and disinfection with OPA and hypochlorite was achieved over 3 to >4 log10 with multiple genotypes of tissue-derived and recombinant HPV isolates.
Interpretation: This work, along with a companion publication from an independent lab in this issue, address a major public health question by showing that HPVs are susceptible to HLDs.
Funding: Advanced Sterilization Products; US NIH (R01CA207368, U19AI084081, P30CA118100).
Keywords: High-level disinfectant; Medical devices; Nosocomial infection; Oncogenic virus; Sexually transmitted disease; Virus disinfection.
Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.