Swab Types Research Articles

Upper respiratory tract detection of Mycoplasma ovipneumoniae employing nasopharyngeal swabs

BackgroundFlock-level prevalence and characterization of Mycoplasma ovipneumoniae is determined almost exclusively using nasal swabbing followed by molecular detection with either quantitative PCR or multi-locus sequence typing. However, the diagnostic performance and efficiency of swabbing the nasal passage compared to other anatomical locations has not been determined within sheep populations. The goal of this research was to assess the diagnostic capability of nasopharyngeal swabs in comparison to nasal swabs for the detection of Mycoplasma ovipneumoniae.ResultsNasal and nasopharyngeal swabs were collected during a controlled exposure study of domestic sheep with Mycoplasma ovipneumoniae. Both swab types were then analyzed via conventional and quantitative PCR. This dataset showed that the use of nasopharyngeal swabs in lieu of nasal swabs resulted in higher sensitivity, reduced inhibition during quantitative PCR, and higher bacterial copy numbers per swab. Moreover, it was demonstrated that diagnostic sensitivity could be further increased during quantitative PCR via ten-fold dilution of the extracted DNA. To confirm these observations in naturally infected animals, we conducted a field study employing a production flock of domestic sheep using both nasal and nasopharyngeal swabbing techniques. Extracted DNA was assessed using the same molecular techniques, where detection of Mycoplasma ovipneumoniae was confirmed by sequencing of either the rpoB or 16S rRNA gene. Similar improvements were observed for nasopharyngeal swabs and template treatment methods within the naturally infected flock.ConclusionsResults demonstrate increased diagnostic sensitivity and specificity when sampling with nasopharyngeal swabs as compared to nasal swabs. Therefore, alternate field-testing strategies employing nasopharyngeal swabs should be considered for diagnosis of the presence of M. ovipneumoniae. Importantly, sample treatment following acquisition was found to affect the sensitivity of quantitative PCR, where dilution of eluted DNA template doubled the calculated sensitivity. This demonstrates that, in addition to anatomical location, the presence of inhibitory components in swab extracts also strongly influences diagnostic performance.

Comparison of Different DNA Sampling and Extraction Protocols for Bacterial and Archaeal Populations Analysis in Water Buffalo

Methane (CH4) is a potent greenhouse gas, and ruminants are a significant source of agricultural emissions. It has been hypothesized that the host's genome controls rumen microbial communities, but robust results require numerous samples. The feasibility of a research project will depend on the ease and representativeness of the sampling method, as well as the cost-efficiency of large-scale sequencing. This study aimed to compare different protocols to investigate whether non-invasive samples could serve as a substitute for ruminal digesta. DNA recovery was tested in various matrices (whole rumen content, feces, and buccal swabs) from five cannulated buffalo cows. Three types of buccal swabs were tested, as well as feces in different forms (as-is, pelleted, or in a glycerol solution) and the rumen content. The study compared different protocols for DNA extraction, including WUR protocol, Maxwell®, and Quick Extract™, and two sampling times. Saliva was a challenging matrix to process, obtaining unsatisfactory DNA yield. Feces showed higher yields when pelleted but lower than rumen. The highest amount of DNA was obtained from whole rumen content using all three DNA extraction methods. Quick Extract was the easiest method to perform, while WUR resulted in the highest yield of DNA, swabs excluded. The Maxwell® method gave satisfactory results with all three matrices. However, further metagenomic analysis is required to verify if the species composition is comparable.

Optimising recovery of DNA from minimally invasive sampling methods: Efficacy of buccal swabs, preservation strategy andDNA extraction approaches for amphibian studies.

Studies in evolution, ecology and conservation are increasingly based on genetic and genomic data. With increased focus on molecular approaches, ethical concerns about destructive or more invasive techniques need to be considered, with a push for minimally invasive sampling to be optimised. Buccal swabs have been increasingly used to collect DNA in a number of taxa, including amphibians. However, DNA yield and purity from swabs are often low, limiting its use. In this study, we compare different types of swabs, preservation method and storage, and DNA extraction techniques in three case studies to assess the optimal approach for recovering DNA in anurans. Out of the five different types of swabs that we tested, Isohelix MS-02 and Rapidry swabs generated higher DNA yields than other swabs. When comparing storage buffers, ethanol is a better preservative than a non-alcoholic alternative. Dried samples resulted in similar or better final DNA yields compared to ethanol-fixed samples if kept cool. DNA extraction via a Qiagen™ DNeasy Blood and Tissue Kit and McHale's salting-out extraction method resulted in similar DNA yields but the Qiagen™ kit extracts contained less contamination. We also found that samples have better DNA recovery if they are frozen as soon as possible after collection. We provide recommendations for sample collection and extraction under different conditions, including budgetary considerations, size of individual animal sampled, access to cold storage facilities and DNA extraction methodology. Maximising efficacy of all of these factors for better DNA recovery will allow buccal swabs to be used for genetic and genomic studies in a range of vertebrates.

3D printed rectal swabs for assessing the gut microbiome, metabolome and inflammation

Investigating the gut microbiome and metabolome frequently requires faecal samples, which can be difficult to obtain. Previous studies have shown that rectal swabs are comparable to faecal samples for analysing gut microbiota composition and key metabolites. In this study, 3D printed rectal swabs were compared with conventional flocked swabs and faecal samples, due to the potential advantages 3D printing as a technique offers for swab production and development. 16S rRNA gene sequencing, qPCR and metabolite profiling (using 1H-NMR spectroscopy) were performed on swab and faecal samples from healthy participants. Faecal calprotectin and total protein analysis were performed on samples from inflammatory bowel disease (IBD) patients. There were no significant differences between both swab types and faecal samples when assessing key measures of alpha and beta diversity, and differences in the abundance of major phyla. There was a strong correlation between both swab types and faecal samples for all combined metabolites detected by NMR. In IBD patients, there was no significant difference in faecal calprotectin and total protein levels between both swab types and faecal samples. These data lead us to conclude that 3D printed swabs are equivalent to flocked swabs for the analysis of the gut microbiome, metabolome and inflammation.

Evaluating Two Sampling Methods for Mycoplasma Bovis Diagnosis in American Bison (Bison bison).

Mycoplasma bovis is a bacterial pathogen endemic to cattle. In the early 2000s, M. bovis emerged as a cause of respiratory disease in American bison (Bison bison), causing significant morbidity and mortality. Bison herds that experience an outbreak of M. bovis are at higher risk for subsequent outbreaks, suggesting that chronic, subclinical infections can be established. Antemortem testing is therefore crucial to disease management; however, the precise sampling method to maximize detection of M. bovis in bison is unknown. We evaluated two sample types-superficial nasal swabs and deep nasopharyngeal swabs-collected from apparently healthy or symptomatic bison from January 2021 through December 2022. We used real-time PCR to detect M. bovis in 76/938 bison (8.1%) from 11 herds. For bison testing positive on at least one swab type, M. bovis was detected in 63/76 (82.8%) deep nasopharyngeal swabs and 29/73 (38.1%) superficial nasal swabs. Agreement between swabs for positive bison was 21% (n=16, kappa coefficient 0.319). We conclude that deep nasopharyngeal swabbing is more sensitive than superficial nasal swabbing for detection of M. bovis in bison and that low agreement between methods may be related to stage of infection. We further tested pooled samples by PCR and found that pooling of up to five samples can be effective to increase throughput and minimize costs. Management of wild bison relies on the ability to relocate animals to maintain gene flow and healthy populations. Sensitive and specific diagnostic tests are needed to inform decisions and minimize risk of transmission, especially from subclinical carriers. This study provides valuable insight that will inform best practices for M. bovis testing, thereby supporting the conservation of bison as healthy wildlife, which in turn promotes ecological restoration, safeguards cultural practices of Tribal Nations, and upholds the bison as a unique American icon.

Improving Consistency and Accuracy: A Novel C. auris Colonization Screening Strategy Using a Nares + Hands Composite Swab

Background: Candida auris is often identified in healthcare settings through bilateral composite of axilla/groin skin swabs screening. Re-screening the same patient has demonstrated inconsistent results over time, complicating the understanding of longitudinal colonization and limiting confidence in negative Results: Previous studies have described identification of colonized patients using other anatomical sites. Here, we compare bilateral composite of nares/hands with bilateral composite of axilla/groin screenings in a cohort of hospitalized patients in Miami, Florida, to assess the use of screening other body sites for C. auris surveillance. Methods: This study took place in a 560-bed academic acute-care facility and included patients previously colonized with C. auris who were cohorted on a 30-bed unit. Bilateral composite samples from both the axilla/groin and nares/hands were obtained simultaneously. Swabs were collected at six different time points at biweekly intervals between March and May 2023 (Figure 1) and sent to the Centers for Disease Control and Prevention for testing with culture and Real-time PCR-based methods. Results: A total of 102 swabs (51 from each swab type) were collected from 19 patients who were each sampled a median of twice (IQR: 1-5). Among the 102 swabs, 35 of 51 (69%) axilla/groin swabs were positive compared with 45 of 51 (88%) nares/hands swabs using culture (Figure 2). Furthermore, 48 of 51 (94%) swabs were positive by culture for both methods, with 15 positive from the nares/hands and one positive from the axilla/groin (Figure 3). Among 11 patients who were tested ≥2 times with nares/hands swabs, 9/11 (81%) tested positive on all sequential swabs via culture and 10/11 (90%) tested positive via PCR (Ct threshold < 3 6.9). Among the same 11 patients but using the axilla/groin swabs, 3/11 (27%) patients tested positive on all sequential swabs using culture, and 5/11 (45%) tested positive using PCR (Figures 2-4). On average, samples collected from nares/hands swabs had lower Ct values (mean=27) compared to axilla/groin swabs (mean=31) (p-value=< 0.001) (Figure 5). Discussion: Identifying the swab site with most consistent C. auris detection is important for surveillance purposes. In our study, there were more positives and consistent positivity for nares/hands by both culture and PCR-based methods, as well as lower Ct values, suggesting that these swabs provide more reliable detection of C. auris colonization. Alternative screening methods deserve consideration as CDC continues to explore whether swabbing of other body sites (e.g., nares, hands) would improve accuracy and consistency when identifying colonized patients.

Evaluations of modes of pooling specimens for COVID-19 screened by quantitative PCR and droplet digital PCR

Though pooling samples for SARS-CoV-2 detection has effectively met the need for rapid diagnostic and screening tests, many factors can influence the sensitivity of a pooled test. In this study, we conducted a simulation experiment to evaluate modes of pooling specimens and aimed at formulating an optimal pooling strategy. We focussed on the type of swab, their solvent adsorption ability, pool size, pooling volume, and different factors affecting the quality of preserving RNA by different virus solutions. Both quantitative PCR and digital PCR were used to evaluate the sampling performance. In addition, we determined the detection limit by sampling which is simulated from the virus of different titers and evaluated the effect of sample-storage conditions by determining the viral load after storage. We found that flocked swabs were better than fibre swabs. The RNA-preserving ability of the non-inactivating virus solution was slightly better than that of the inactivating virus solution. The optimal pooling strategy was a pool size of 10 samples in a total volume of 9 mL. Storing the collected samples at 4 °C or 25 °C for up to 48 h had little effect on the detection sensitivity. Further, we observed that our optimal pooling strategy performed equally well as the single-tube test did. In clinical applications, we recommend adopting this pooling strategy for low-risk populations to improve screening efficiency and shape future strategies for detecting and managing other respiratory pathogens, thus contributing to preparedness for future public health challenges.

What Are the Limitations and Challenges of Swab-Based DNA Sampling?

Selecting the optimal sampling method is an essential component of the DNA analysis process. Errors or omissions in targeting and gathering relevant samples can significantly reduce the likelihood of obtaining a valuable DNA profile, affecting the profile’s quality and evidential value and ultimately hindering its ability to support the justice system. While DNA typing techniques have become significantly more sensitive in recent years, there is an ongoing need for further advancements in the recovery of DNA from crime scenes. It is essential to improve the accuracy and reliability of forensic investigations, particularly in cases where only tiny amounts of DNA are present, such as touch DNA samples or degraded forensic evidence. Parameters, including swab material, type of substrate, and swabbing protocol, that influence the efficiency of a swab are discussed in this review. This is followed by a literature review of studies that have compared swab types and/or other sampling conditions. While swabs are the most-used collection tools at a crime scene, alternatives are available. These alternatives are reviewed, including their advantages and disadvantages. A critical discussion and conclusions make clear that, unfortunately, neither swabs nor their alternatives are highly effective in recovering DNA from a substrate.

New Manual Quantitative Polymerase Chain Reaction Assay Validated on Tongue Swabs Collected and Processed in Uganda Shows Sensitivity That Rivals Sputum-based Molecular Tuberculosis Diagnostics.

Sputum-based testing is a barrier to increasing access to molecular diagnostics for tuberculosis (TB). Many people with TB are unable to produce sputum, and sputum processing increases assay complexity and cost. Tongue swabs are emerging as an alternative to sputum, but performance limits are uncertain. From June 2022 to July 2023, we enrolled 397 consecutive adults with cough >2 weeks at 2 health centers in Kampala, Uganda. We collected demographic and clinical information, sputum for TB testing (Xpert MTB/RIF Ultra and 2 liquid cultures), and tongue swabs for same-day quantitative polymerase chain reaction (qPCR) testing. We evaluated tongue swab qPCR diagnostic accuracy versus sputum TB test results, quantified TB targets per swab, assessed the impact of serial swabbing, and compared 2 swab types (Copan FLOQSWAB and Steripack spun polyester). Among 397 participants, 43.1% were female, median age was 33 years, 23.5% were diagnosed with human immunodeficiency virus, and 32.0% had confirmed TB. Sputum Xpert Ultra and tongue swab qPCR results were concordant for 98.2% (95% confidence interval [CI]: 96.2-99.1) of participants. Tongue swab qPCR sensitivity was 92.6% (95% CI: 86.5 to 96.0) and specificity was 99.1% (95% CI: 96.9 to 99.8) versus microbiological reference standard. A single tongue swab recovered a 7-log range of TB copies, with a decreasing recovery trend among 4 serial swabs. Swab types performed equivalently. Tongue swabs are a promising alternative to sputum for molecular diagnosis of TB, with sensitivity approaching sputum-based molecular tests. Our results provide valuable insights for developing successful tongue swab-based TB diagnostics.

Efficiency and novelty of using environmental swabs for dry-surface biofilm recovery.

Studies on the epidemiology of dry-surface biofilms (DSBs) within healthcare settings have shown an almost universal distribution across frequently touched items. Despite a growing body of evidence for DSBs in hospitals, little attention has been paid to the recovery capacity of techniques used to detect these microbial communities. Biofilms are inherently difficult to remove from surfaces due to adhesive substances within their matrix and may act as sources of infection, but to what extent is largely unknown. In this study, we evaluate the recovery efficiencies of commonly used environmental swabs against DSBs containing 7.24 log10 Acinetobacter baumannii cm-2, using a drip flow reactor and desiccation cycle. Biofilm presence was visually confirmed using episcopic differential interference contrast microscopy combined with epifluorescence and quantified using sonicated viable plate counts. The swab materials used comprised foam, viscose and cotton, all of which were pre-moistened using a buffer solution. The surfaces were vigorously swabbed by each material type and the resultant microbe populations for both swabs and remaining DSBs were quantified. Our results found foam-tipped swabs to be superior, detecting on average 30 % of the original DSB contamination; followed by viscose (6 %) and cotton (3 %). However, no distinct difference was revealed in the concentration of microbes remaining on the surface after swabbing for each swab type, suggesting there is variation in the capacity for each swab to release biofilm-associated micro-organisms. We conclude whilst environmental swabs do possess the ability to detect biofilms on dry surfaces, the reduced efficiencies are likely to cause an underestimation of the microbes present and should be considered during clinical application.

Efficacy of sample collection without virus transport medium in suspected enteroviral infections for molecular diagnosis.

Clinical swabs with suspected viral infection are usually transported in virus transport medium (VMT). During epidemics/pandemics, tampons without VTM would be more suitable for saving space and cost. This study was conducted to verify the applicability of throat swabs without VTM in the diagnosis/screening of enteroviral infections by polymerase chain reaction (PCR) in avolunteer study group. Three different swab types were used in 40 volunteers: swabs with two different tips (cotton- or synthetic-tipped) without VTM and standard synthetic tips with VTM. The swabs were processed immediately or after 12 days of storage at either -80°C or +4°C. The molecular analysis included viral RNA extraction, and combination of reverse transcriptase PCR and nested PCR. Enteroviral RNA was detected in 15% (6/40) of the studied volunteers. When processed immediately, the results for all three swab types were compatible. Swabs without VTM may be used for collection of clinical samples in the diagnosis of suspected enteroviral infections or as potential screening tools for enteroviruses (Tab. 2, Ref. 15). Keywords: enterovirus infection, swab, transport medium, PCR, molecular diagnostics.

Oral swabs with a rapid molecular diagnostic test for pulmonary tuberculosis in adults and children: a systematic review

Tuberculosis is a leading cause of infectious disease mortality worldwide, but diagnosis of pulmonary tuberculosis remains challenging. Oral swabs are a promising non-sputum alternative sample type for the diagnosis of pulmonary tuberculosis. We aimed to assess the diagnostic accuracy of oral swabs to detect pulmonary tuberculosis in adults and children and suggest research implications. In this systematic review, we searched published and preprint studies from Jan 1, 2000, to July 5, 2022, from eight databases (MEDLINE, Embase, Scopus, Science Citation Index, medRxiv, bioRxiv, Global Index Medicus, and Google Scholar). We included diagnostic accuracy studies including cross-sectional, cohort, and case-control studies in adults and children from which we could extract or derive sensitivity and specificity of oral swabs as a sample type for the diagnosis of pulmonary tuberculosis against a sputum microbiological (nucleic acid amplification test [NAAT] on sputum or culture) or composite reference standard. Of 550 reports identified by the search, we included 16 eligible reports (including 20 studies and 3083 participants) that reported diagnostic accuracy estimates on oral swabs for pulmonary tuberculosis. Sensitivity on oral swabs ranged from 36% (95% CI 26-48) to 91% (80-98) in adults and 5% (1-14) to 42% (23-63) in children. Across all studies, specificity ranged from 66% (95% CI 52-78) to 100% (97-100), with most studies reporting specificity of more than 90%. Meta-analysis was not performed because of sampling and testing heterogeneity. Sensitivity varies in both adults and children when diverse methods are used. Variability in sampling location, swab type, and type of NAAT used in accuracy studies limits comparison. Although data are suggestive that high accuracy is achievable using oral swabs with molecular testing, more research is needed to define optimal methods for using oral swabs as a specimen for tuberculosis detection. The current data suggest that tongue swabs and swab types that collect increased biomass might have increased sensitivity. We would recommend that future studies use these established methods to continue to refine sample processing to maximise sensitivity. Bill and Melinda Gates foundation (INV-045721) and FIND (Netherlands Enterprise Agency on behalf of the Minister for Foreign Trade and Development Cooperation [NL-GRNT05] and KfW Development Bank, German Federal Ministry of Education and Research [KFW-TBBU01/02]).

Chemical Analysis of Sexual Lubricant Residue: A Comparison of Medical Examination Swabs Analyzed Using Spectroscopic Techniques

Sexual assault kits are the standard method for collecting and preserving sexual assault evidence. During the sexual assault examination, swabs are commonly used to collect bodily fluids as sexual assault evidence from the vagina, anus, mouth, and skin. The type of fiber swab used during collection can greatly influence the recovery of the substrate. In cases where lubricant residue may be present, it would be useful to identify the swab type that would be the most efficient in the collection of lubricant residues. In this study, four types of swabs with different fibers (i.e., cotton, polyester, rayon, and foam) with sexual lubricants present, were extracted in various solvents. The extracts were analyzed using attenuated total reflectance Fourier-transform infrared (ATR-FTIR) and Raman spectroscopy. The Pearson correlation coefficient (PCCs) test was applied to determine a pairwise comparison between swab lube extracts and the standard lubricant reference. Visual comparisons of the lubricant reference, blank fiber swab, and the fiber lubricant extract were used to determine peak overlap, significance, and matrix interference.

Agreement among deep nasopharyngeal sampling culture results for 3 different swab types in preweaning dairy calves

Accurate isolation and identification of pathogens for an animal with bovine respiratory disease are of critical importance to direct appropriate decision-making related to the treatment of individual animals, as well as control and prevention options in a herd setting. The objective of this study was to compare nasopharyngeal sampling approaches to evaluate accuracy and agreement for the recovery of Mannheimia haemolytica (MH) and Pasteurella multocida (PM) from deep nasopharyngeal swabs (DNS) using 3 different swabs. Deep nasopharyngeal samples were collected from 45 dairy calves using 3 swabs: (1) double-guarded culture swab (DGS); (2) single-guarded culture swab (SGS); and (3) unguarded culture swab (UGS). To evaluate the degree of agreement between DGS, SGS, and UGS, culture results were compared for each calf sampled by using a kappa agreement test. Overall, findings from our study support that when using either SGS or DGS for DNS sampling of preweaning calves, a high agreement for recovery of PM is observed. A low recovery of MH was observed in the study, limiting the conclusion comparing the 3 DNS methods. Use of UGS is considered a potential alternative; however, a higher percentage of polymicrobial growth was found with UGS samples.

Diagnostic Accuracy of Saliva for Molecular Detection of SARS CoV-2 for Diagnosis of COVID 19: a Comparative Study

Throat swab, Nasal swab, Nasopharyngeal swab, Bronchoalveolar lavage fluid and Endotracheal aspirate are the recommended samples by Indian Council of Medical Research for molecular detection of SARS-CoV-2. Saliva specimen is less invasive, can be collected by oneself thus minimizing the risk to the healthcare workers to SARS-CoV-2 exposure. The present study was aimed to evaluate better possible sample collection method among nasal swab, Throat swab and saliva samples of patients for precise COVID-19 diagnosis. A prospective study conducted for diagnosis of COVID-19 samples. three type of samples Nasal and Throat swab and saliva collected for COVID-19 diagnosis. If sample was found positive then Throat and nasal swabs were collected every alternative day while saliva collected every day for COVID-19 diagnosis by RT-PCR. 172 samples of patients were found to be positive for COVID-19. 103 (59.88 %) males and 69 (40.11 %) were females. Throat and Nasal swabs were collected every alternative day. Nasal swab was the best method of sample collection and gave most effective results followed by throat swab in comparison with the saliva sample. Saliva specimen showed positivity only for upto 3 days, while TS and NS specimens showed higher positivity in comparison with saliva specimens for upto 7 days. Further research on usefulness of less invasive saliva specimen is required.

The impact of the COVID-19 pandemic on the prevalence and genotype distribution of HPV infection in Beijing, China.

Human papillomavirus (HPV) is one of the most common sexually transmitted infections nationwide. The COVID-19 pandemic has greatly influenced on the HPV prevention project. The objective of this study was to examine the influence of the pandemic on HPV prevalence and genotype distribution in Beijing, China. A total of 44 401 genital swabs were obtained from outpatients at Peking Union Medical College Hospital during two distinct periods: the prepandemic stage from January 2017 to December 2019 and the pandemic stage from January 2020 to December 2022. During the prepandemic and pandemic stages, a total of 33 531 and 10 870 swabs were respectively collected. Fifteen high-risk HPV(HR-HPV) DNA type and a combination of two low-risk (LR-HPV) types (6/11) of genital swabs were detected to compare the HPV infection rates and genotype distributions in two stages. The results showed that the pandemic period witnessed a decrease in the overall HPV infection rate from 33.43% (11 245/33 531) to 29.43% (5527/18 780) compared to the prepandemic. There were statistically significant differences in infection rates between females and males (p < 0.05). Single infection was the predominant type while multiple infection was more prevalent in males than females in both prepandemic and pandemic periods. HR-HPV infection constituted the majority of infections and cannot be disregarded. The distribution of HR-HPV genotypes exhibited little variation before and after the outbreak, but there were some differences between females and males. HPV 16, 52, 58, 56, and 66 were the most commonly detected genotypes in females, whereas HPV 16, 52, 51, 58, and 18 were frequently detected in males. Additionally, HPV 6/11 exhibited a higher prevalence in males than in females. Notably, the age group of 31-40 years old exhibited the highest prevalence of HPV and the lowest infection rate was detected among individuals aged ≤20 years (p < 0.05), which remained relatively consistent before and during the pandemic. These findings underscore the importance of monitoring the trend of HPV epidemic and offer valuable insights for the prevention, treatment, and scientific investigation of HPV in the post-COVID-19 era.

Chemical-physical investigations of nine types of nasopharyngeal swabs for the PCR analyses

During the SARS-Cov-2 pandemic, a test of samples collected through naso/oropharyngeal swab was set up; for this aim new swabs were developed. Materials and methods: The laboratory New Nanodiagnostics srl (Modena - Italy) analyzed nine different types of swabs used to collect human organic material for PCR diagnostic test for the SARS-CoV-2 infection. The swabs were observed under Optical Microscope and analyzed by Field Emission Gun Environmental Scanning Electron Microscope (FEGE-SEM) coupled with an Energy Dispersive System (EDS), to verify their morphology and chemical composition. Three different morphologies and nanostructures, along with their chemical composition were identified. Surprisingly enough, the presence of identified chemical contaminants like Titanium-Silicon-Aluminum or Silicon- Aluminium-Chromium-Manganese does not be understandable nor is it explained in the data sheet. Some fibers also present a nanostructured coating of Silicon-Zirconium. This might be of concern, as their presence could invalidate the accuracy of the PCR testing. In addition to that, the biocompatibility of the medical devices is discussed since a particular tendency of the glassy fibers to break has been verified. The presence of broken fibers in the nasal and oropharyngeal mucosa can cause irreversible damages. Finally, after their use, the swabs must be incinerated and their fumes contribute to the increase of the environmental pollution.

Performance of Different Cotton and Nylon Swabs on DNA Recovery and Storage

Touch DNA samples are routine yet challenging pieces of evidence that provide investigators with information that helps them solve crimes. However, this type of evidence can be easily lost if the correct collection method is not used. This problem could be overcome with an optimal method of collection that increases the amount of touch DNA collected from different types of surfaces. Better-quality touch DNA can increase the chances of getting a full genetic profile. This study was divided into two parts which aimed to assess whether the type of swab used on different surfaces will significantly increase DNA recovery, concentrations, and the DNA preservation during three different timeframes (24h, 1 month and 3 months). Two different cotton swabs and Nylon swabs were used to lift touch DNA on three different surfaces (glass, plastic and wood) to identify the most suitable method of collection across all three surfaces. A total of 72 samples were lifted (3 replicates from each swab on 3 different surfaces) from two different participants (Male and Female) which were left to dry for 14 days in room temperature prior to DNA extraction. DNA preservation of the swabs was observed while using three dilutions of blood sample which was prepared from one of the volunteers (1:1 – 1:10 – 1:20) where 10 uL of each dilution was pipetted onto the four types of swabs in three replicates (n=36) to observe the preservation over three different timeframes 24h storage, 1 Month and 3 Months with a total of 108 samples. The COPAN CLASSIQSwabsTM Dry swab showed an overall average result during the storage periods of 24h with (1:1) dilution by (2.694ng/μL), (1:10) dilution with (0.548ng/μL) and (1:20) dilution with (0.143ng/μL). Results for the period of 1 Month also showed an average of (1:1) dilution with (2.825ng/μL), (1:10) dilution with (0.361ng/μL) and (1:20) dilution with (0.156ng/μL). These findings can be helpful for laboratories and crime scene investigators to optimize DNA sample collection and preservation based on their workflow.

Methods for virus recovery from environmental surfaces to monitor infectious viral contamination

Accurate quantification of infectious contaminants on environmental surfaces, particularly infectious viruses, is essential for contact transmission risk assessment; however, difficulties in recovering viruses from surfaces using swabs complicates this quantification process. Herein, we identified the factors that significantly affected virus recovery rates and developed an ideal swab method that yielded the highest rate of virus recovery. We comprehensively analyzed the effects of swab type (cotton/polyester), swab water content (wet/dry conditions), surface material, and surface area on the rates of viral RNA and infectious virus recovery.The virus recovery rate was significantly lower than the viral RNA recovery rate (P < 0.01), indicating difficulty in the quantification of infectious viruses. The virus recovery rate was significantly higher under wet conditions than that under dry conditions (P < 0.006), and the virus recovery rate obtained using cotton swabs was significantly higher than that using polyester swabs (P < 0.0001). Furthermore, the virus recovery rate had a strong negative correlation (correlation coefficient >0.8) with the target surface area. The maximum surface area where the virus recovery rate was ≥10% (MSA-10%) was identified as the maximum quantifiable area. For influenza virus recovery, MSA-10% on polyvinyl chloride (PVC) sheet, PVC leather, stainless steel, silicone, glass, and polycarbonate surfaces was 66.7, 193, 60.2, 144, 105, and 15.6 cm2, respectively. For feline calicivirus recovery, MSA-10% on PVC sheet, PVC leather, stainless steel, silicone, glass, and polycarbonate surfaces was 210, 111, 2120, 250, 322, and 180 cm2, respectively.The most accurate and ideal method for quantifying infectious viruses on environmental surfaces with the highest recovery rates meets three specifications: “wet conditions,” “the use of cotton swabs,” and “a target surface area of approximately 10 cm2.

Challenges and insights in the exploration of the low abundance human ocular surface microbiome.

The low microbial abundance on the ocular surface results in challenges in the characterization of its microbiome. The purpose of this study was to reveal factors introducing bias in the pipeline from sample collection to data analysis of low-abundant microbiomes. Lower conjunctiva and lower lid swabs were collected from six participants using either standard cotton or flocked nylon swabs. Microbial DNA was isolated with two different kits (with or without prior host DNA depletion and mechanical lysis), followed by whole-metagenome shotgun sequencing with a high sequencing depth set at 60 million reads per sample. The relative microbial compositions were generated using the two different tools MetaPhlan3 and Kraken2. The total amount of extracted DNA was increased by using nylon flocked swabs on the lower conjunctiva. In total, 269 microbial species were detected. The most abundant bacterial phyla were Actinobacteria, Firmicutes and Proteobacteria. Depending on the DNA extraction kit and tool used for profiling, the microbial composition and the relative abundance of viruses varied. The microbial composition on the ocular surface is not dependent on the swab type, but on the DNA extraction method and profiling tool. These factors have to be considered in further studies about the ocular surface microbiome and other sparsely colonized microbiomes in order to improve data reproducibility. Understanding challenges and biases in the characterization of the ocular surface microbiome may set the basis for microbiome-altering interventions for treatment of ocular surface associated diseases.