Comparison of oral fluid collectors for use in a rapid point-of-care diagnostic device

Saliva sampling methods. Cariogenic streptococci count using two different methods of saliva collection in children

The aim of this study is to compare the efficacy of two methods for collecting saliva samples from infants under 2 years of age for cariogenic streptococci (CS) count. Two collection methods were applied in 11 infants. In Method (A), saliva samples were collected by swabbing the inner cheek mucosa and floor of the mouth in figure of eight motions with a sterile cotton swab until it was soaked. In method (B), saliva samples were collected by aspiration of 1 ml of saliva with a sterile plastic syringe on the floor of the mouth, after stimulation with glove. The samples were cultured in modified Gold's broth (MSMG), and on trypticase, yeast extract, sucrose, cystine and bacitracin culture medium (TYSCB). In method (A), the swab with the sample was unloaded in situ on TYSCB and placed in PBS medium for transport. Then, 100 μl of the eluate was seeded in MSMG. In method (B) 100 μl were seeded in TYSCB and 100 μl in MSMG. Both culture media were incubatedundercapnophilicconditions for 48 hours at 37 °C. Colony forming units (CFU/ml) were counted by calibrated operators (kappa = 0.75). The presence of cariogenic streptococci (CS) (Streptococcus mutans-Streptococcus sobrinus) was determined by qPCR in the samples collected by both methods. The CFU/ml counts in MSMG differed significantly between methods (p = 0.021). In TYSCB, the recovery of CFU/ml was higher in method (A), without significant difference (p = 0.705). The molecular technique detected presence of CS, with no difference between collection methods. Collecting saliva samples by swabbing proved more effective in terms of recovery of microorganisms, and did not affect the detection of presence of CS by molecular techniques.

Stabilization of Salivary Biomarkers

The use of saliva as a diagnostic biofluid has been increasing in recent years, thanks to the identification and validation of new biomarkers and improvements in test accuracy, sensitivity, and precision that enable the development of new noninvasive and cost-effective devices. However, the lack of standardized methods for sample collection, treatment, and storage contribute to the overall variability and lack of reproducibility across analytical evaluations. Furthermore, the instability of salivary biomarkers after sample collection hinders their translation into commercially available technologies for noninvasive monitoring of saliva in home settings. The present review aims to highlight the status of research on the challenges of collecting and using diagnostic salivary samples, emphasizing the methodologies used to preserve relevant proteins, hormones, genomic, and transcriptomic biomarkers during sample handling and analysis.

Potential of Salivary Biomarkers in Autism Research: A Systematic Review

The diagnostic process for autism spectrum disorders (ASD) is based on a behavioral analysis of the suspected individual. Despite intensive research, no specific and valid biomarker has been identified for ASD, but saliva, with its advantages such as non-invasive collection, could serve as a suitable alternative to other body fluids. As a source of nucleic acid of both human and microbial origin, protein and non-protein molecules, saliva offers a complex view on the current state of the organism. Additionally, the use of salivary markers seems to be less complicated not only for ASD screening but also for revealing the etiopathogenesis of ASD, since enrolling neurotypical counterparts willing to participate in studies may be more feasible. The aim of the presented review is to provide an overview of the current research performed on saliva in relation to ASD, mutual complementing, and discrepancies that result in difficulties applying the observed markers in clinical practice. We emphasize the methodological limitations of saliva collection and processing as well as the lack of information regarding ASD diagnosis, which is critically discussed.

Impact of Saliva Collection and Processing Methods on Aspartate Aminotransferase, Creatin Kinase and Lactate Dehydrogenase Activities

We aimed to investigate the impact of saliva collection and processing methods on AST, CK and LDH. Saliva was collected from 17 healthy participants by a passive drool. Each saliva sample was distributed into 3 aliquots: not treated, centrifuged, and passed through cotton. Centrifugation improved the precision of assays and produced lower values of AST and CK. The use of cotton resulted in decreased levels of LDH. This data stress the importance of the standardization of sample processing to measure enzymes in saliva.

Microfluidic Line-Free Mass Sensor Based on an Antibody-Modified Mechanical Resonator

This research proposes a mass sensor based on mechanical resonance that is free from power supply lines (line-free) and incorporates both microfluidic mechanisms and label-free techniques to improve its sensitivity and reusability. The microfluidic line-free mass sensor comprises a disk-shaped mechanical resonator, a separate piezoelectric element used to excite vibrations in the resonator, and a microfluidic mechanism. Electrical power is used to actuate the piezoelectric element, leaving the resonator free from power lines. The microfluidic mechanism allows for rapid, repeat washings to remove impurities from a sample. The microfluidic line-free mass sensor is designed as a label-free sensor to enable high-throughput by modifying and dissociating an antibody on the resonator. The resonator was fabricated by photolithography and the diameter and thickness were 4 mm and 0.5 mm, respectively. The line-free mass sensor enabled a high Q-factor and resonance frequency of 7748 MHz and 1.402 MHz, respectively, to be achieved even in liquids, facilitating the analysis of human salivary cortisol. The line-free mass sensor could be used for repeated measurements with the microfluidic mechanism, and the resonator could be fully washed out. It was concluded that the microfluidic line-free mass sensor was suitable to analyze the concentration of a salivary hormone, cortisol, in human saliva samples, and that it provided high-throughput suitable for point-of-care testing.

Comparison of oral fluid collection methods for the molecular detection of hepatitis B virus

BACKGROUND

This study aims to compare the efficiency of four oral fluid collection methods (Salivette, FTA Card, spitting and DNA-Sal) to detect HBV DNA by qualitative PCR.

MATERIALS AND METHODS

Seventy-four individuals (32 HBV reactive and 42 with no HBV markers) donated serum and oral fluid. In-house qualitative PCR to detect HBV was used for both samples and commercial quantitative PCR for serum.

RESULTS

HBV DNA was detected in all serum samples from HBV-infected individuals, and it was not detected in control group. HBV DNA from HBV group was detected in 17 samples collected with Salivette device, 16 samples collected by FTA Card device, 16 samples collected from spitting and 13 samples collected by DNA-Sal device. Samples that corresponded to a higher viral load in their paired serum sample could be detected using all oral fluid collection methods, but Salivette collection device yielded the largest numbers of positive samples and had a wide range of viral load that was detected.

CONCLUSION

It was possible to detect HBV DNA using all devices tested, but higher number of positive samples was observed when samples were collected using Salivette device, which shows high concordance to viral load observed in the paired serum samples.

Rapid Assessment of Drugs of Abuse

Laboratory testing for drugs of abuse has become standard practice in many settings both forensic and clinical. Urine is the predominant specimen, but other specimens are possible including hair, nails, sweat, and oral fluid. Point-of-care test kits provide for rapid analysis at the site where specimens are collected allowing for immediate action on the results. POCT is based on immunochromatography where the drug in the patient's sample competes with drug and antibody conjugates in the test to develop or block the development of a colored line. Most POCTs are visually interpreted in a few minutes. The potential for false positives is possible due to drug cross-reactivity with the antibodies in the test. False negatives are also possible due to dilution of the sample and the potential for adulteration or sample substitution by the patient. POCT shows more variability than central laboratory testing because of the variety of operators involved in the testing process, but POCT has good agreement for most tests with mass spectrometry provided comparable cutoffs and cross-reactivity of drugs/metabolites are considered. Validation of the test performance with the intended operators will identify potential interferences and operational issues before implementing the test in routine practice. POCT offers faster turnaround of test results provided the limitations and challenges of the test are considered.

Salivary biomarkers of oxidative stress: A critical review

Human saliva is an increasingly attractive medium for biomarker discovery due to its amenability to noninvasive and repeated sampling, ease of collection and processing, and suitability for single analyte or metabolomic measurements. Salivary biomarkers of oxidative stress reflect local and systemic pathologies and may inform on the diagnosis, prognosis, and therapeutic responsiveness of numerous human diseases. However, for many of the disorders investigated, data reporting on alterations in salivary redox homeostasis are often highly conflicted across studies. We surveyed the available biomedical literature on this topic and noted significant discrepancies in the study designs, target populations, and operating procedures which likely contribute to the discordant data sets reported. Based on these observations, guidelines are provided to minimize interlaboratory variability in redox biomarker discovery based on human saliva.

Measles elimination in Italy: data from laboratory activity, 2011-2013

BACKGROUND

The European Regional Office of the World Health Organization developed a strategic approach to halt the indigenous transmission of measles in its 53 Member States by 2015, World Health Organization [1]. Many European countries, including Italy began the implementation of national programs to reach this goal.

OBJECTIVES

To describe and discuss the results of laboratory activity in measles surveillance, performed from January 2011 to December 2013 by the Italian National Reference Laboratory for Measles and Rubella.

STUDY DESIGN

Samples of suspected measles cases were collected from different Italian regions to confirm clinical diagnosis. Anti-measles IgM antibodies detection by Enzyme-Linked Immunosorbent Assay and/or molecular detection by Reverse Transcriptase-Polymerase Chain Reaction assay were performed. Positive samples were sequenced for viral characterization.

RESULTS AND CONCLUSIONS

According to results from the National Reference Laboratory's activity urine and blood seem to be the best specimens for measles laboratory surveillance. Phylogenetic analysis revealed a co-circulation of the genotypes D4 and D8 during the reviewed period, a cluster of B3 and sporadic cases of D9 and H1.

Saliva: a fluid of study for OMICS

Saliva is a fluid that can be collected easily and noninvasively. Its functions in the oral cavity are well known. Advances in molecular biology and technology, as well as research conducted by the various disciplines of omics (genomics, transcriptomics, proteomics, metabolomics, and metagenomics) have contributed to the identification and characterization of salivary components, including DNA, RNA, proteins, metabolites, and microorganisms. These biomolecules enter the saliva through extracellular and intracellular routes, providing information from several organs and systems and raising the possibility of their use as disease biomarkers. In recent years, these factors have expanded the potential use of saliva as a diagnostic fluid for oral and systemic diseases. This review integrates information regarding salivary biomolecules studied through omics and explores their utility as biomarkers for the diagnosis of several infectious and noninfectious diseases, and the opportunity they represent for the development of point of care devices for clinical application. We also discuss the advantages, disadvantages, and challenges to be overcome in order to establish saliva as a useful fluid for the accurate diagnosis and monitoring of a wide range of diseases.

Development of a generic microfluidic device for simultaneous detection of antibodies and nucleic acids in oral fluids

A prototype dual-path microfluidic device (Rheonix CARD) capable of performing simultaneously screening (antigen or antibody) and confirmatory (nucleic acid) detection of pathogens is described. The device fully integrates sample processing, antigen or antibody detection, and nucleic acid amplification and detection, demonstrating rapid and inexpensive “sample-to-result” diagnosis with performance comparable to benchtop analysis. For the chip design, a modular approach was followed allowing the optimization of individual steps in the sample processing process. This modular design provides great versatility accommodating different disease targets independently of the production method. In the detection module, a lateral flow (LF) protocol utilizing upconverting phosphor (UCP) reporters was employed. The nucleic acid (NA) module incorporates a generic microtube containing dry reagents. Lateral flow strips and PCR primers determine the target or disease that is diagnosed. Diagnosis of HIV infection was used as a model to investigate the simultaneous detection of both human antibodies against the virus and viral RNA. The serological result is available in less than 30 min, and the confirmation by RNA amplification takes another 60 min. This approach combines a core serological portable diagnostic with a nucleic acid-based confirmatory test.

Evaluation of saliva collection devices for the analysis of proteins

BACKGROUND

Human saliva mirrors the body's health and can be collected non-invasively, does not require specialized skills and is suitable for large population based screening programs. The aims were twofold: to evaluate the suitability of commercially available saliva collection devices for quantifying proteins present in saliva and to provide levels for C-reactive protein (CRP), myoglobin, and immunoglobin E (IgE) in saliva of healthy individuals as a baseline for future studies.

METHODS

Saliva was collected from healthy volunteers (n=17, ages 18-33years). The following collection methods were evaluated: drool; Salimetrics® Oral Swab (SOS); Salivette® Cotton and Synthetic (Sarstedt) and Greiner Bio-One Saliva Collection System (GBO SCS®). We used AlphaLISA® assays to measure CRP, IgE and myoglobin levels in human saliva.

RESULTS

Significant (p<0.05) differences in the salivary flow rates were observed based on the method of collection, i.e. salivary flow rates were significantly lower (p<0.05) in unstimulated saliva (i.e. drool and SOS), when compared with mechanically stimulated methods (p<0.05) (Salivette® Cotton and Synthetic) and acid stimulated method (p<0.05) (SCS®). Saliva collected using SOS yielded significantly (p<0.05) lower concentrations of myoglobin and CRP, whilst, saliva collected using the Salivette® Cotton and Synthetic swab yielded significantly (p<0.05) lower myoglobin and IgE concentrations respectively.

CONCLUSIONS

The results demonstrated significantly relevant differences in analyte levels based on the collection method. Significant differences in the salivary flow rates were also observed depending on the saliva collection method. The data provide preliminary baseline values for salivary CRP, myoglobin, and IgE levels in healthy participants and based on the collection method.

Saliva as an analytical matrix: state of the art and application for biomonitoring

Analytical tests to measure chemicals in saliva can be employed for numerous analytes, endogenous compounds or xenobiotics. The objective was to determine which chemicals can be analysed with this matrix, which analytical methods are applicable, and what application is possible for biomonitoring. We reviewed the literature using three databases, MEDLINE, PubMed and Scopus, collecting articles on different kinds of analysis in saliva. Studies were principally about molecules of clinical interest, xenobiotics, especially drugs of abuse, and chemicals used at workplaces; some substances show no relevant correlation with exposure data while others seems to be of particular interest for systematic use for biomonitoring. Currently, saliva is used far less than other biological fluids but its use for biomonitoring of exposure to chemicals might open up new areas for research and would certainly simplify the collection of biological samples.

Salivary biosensors for screening trauma-related psychopathology

After facial trauma, a distinct subset of patients goes on to develop mental health problems including recalcitrant psychopathology. Early identification of maladaptive stress reactions provides opportunities for initiating preemptive mental health interventions and hinges on the surgeon's ability to differentiate between transient distress and precursors of recalcitrant psychiatric sequelae. The comprehensive care of injured patients will benefit greatly from objective adjuncts and decision-making tools to complement the clinical evaluation. This article addresses meeting the need for practical, standardized, and reliable screening strategies through promising developments in the use of stress response biomarkers and biosensing technology. The systematic interrogation of differentially expressed stress response biomarkers in saliva now permits rapid assessment of the psychopathogical response to the stressor. Quantitative, point-of-use measurements of the traumatic stress response will greatly improve the nosology of posttraumatic stress disorders and help advance the screening, diagnosis, treatment, and prevention of mental health consequences of violence and trauma.

Rapid saliva processing techniques for near real-time analysis of salivary steroids and protein

INTRODUCTION

Point-of-care (POC) measurements using saliva samples have immense potential to assess systemic health and wellbeing, but sample viscosity and contaminants can affect analyses. We sought a portable clean-up method for whole saliva appropriate for use with POC measurement techniques such as biosensors.

METHODS

Whole saliva from each of 13 male subjects was split into 5 fractions. Each fraction was treated with a different clean-up process: a freeze-thaw-centrifuge (FTC) step; centrifugation alone; or passage through a Mini-UniPrep polyethersulfone filter, cotton Salivette, or foam Oracol device. Following clean-up, each subject's treated saliva fractions were assayed for cortisol, testosterone, dehydroepiandrosterone (DHEA), and protein concentrations. The effects of clean-up methods on nonspecific binding (NSB) in a biosensor were also assessed.

RESULTS

Compared with FTC, no analytes were affected by centrifugation alone. Cotton Salivettes significantly altered all analytes, with increases in cortisol (+64%), testosterone (+126%), and DHEA (off-scale) levels, and decreased protein (-21%) and biosensor NSB (-75%). Oracol foam devices decreased DHEA levels by 28%. Mini-UniPrep filtration decreased testosterone (-45%) and DHEA (-66%) concentrations while increasing cortisol (+40%).

CONCLUSION

No method was optimal for all analytes, highlighting the need for validation of saliva treatment methods before their adoption in rapid POC analyses.

Development of a microfluidic device for detection of pathogens in oral samples using upconverting phosphor technology (UPT)

Confirmatory detection of diseases, such as HIV and HIV-associated pathogens in a rapid point-of-care (POC) diagnostic remains a goal for disease control, prevention, and therapy. If a sample could be analyzed onsite with a verified result, the individual could be counseled immediately and appropriate therapy initiated. Our group is focused on developing a microfluidic "lab-on-a-chip" that will simultaneously identify antigens, antibodies, RNA, and DNA using a single oral sample. The approach has been to design individual modules for each assay that uses similar components (e.g., valves, heaters, metering chambers, mixers) installed on a polycarbonate base with a common reporter system. Assay miniaturization reduces the overall analysis time, increases accuracy by simultaneously identifying multiple targets, and enhances detector sensitivity by upconverting phosphor technology (UPT). Our microfluidic approach employs four interrelated components: (1) sample acquisition-OraSure UPlink collectors that pick-up and release bacteria, soluble analytes, and viruses from an oral sample; (2) microfluidic processing-movement of microliter volumes of analyte, target analyte extraction and amplification; (3) detection of analytes using UPT particles in a lateral flow system; and (4) software for processing the results. Ultimately, the oral-based microscale diagnostic system will detect viruses and bacteria, associated pathogen antigens and nucleic acids, and antibodies to these pathogens.

Saliva specimen: a new laboratory tool for diagnostic and basic investigation

The assay of saliva is an increasing area of research with implications for basic and clinical purposes. Although this biological fluid is easy to manipulate and collect, careful attention must be directed to limit variation in specimen integrity. Recently, the use of saliva has provided a substantial addition to the diagnostic armamentarium as an investigative tool for disease processes and disorders. In addition to its oral indications, the analysis of saliva provides important information about the functioning of various organs within the body. In this respect, endocrine research certainly occupies a central role. The present review considers the laboratory aspects of salivary assays with respect to the different analytes including ions, drugs and various non-protein/protein compounds such as hormones and immunoglobulins. This review also examines the consequences of preanalytical variation with respect to collection strategy and subsequent storage conditions. It is likely that the use of saliva in assays will continue to expand thus providing a new instrument of investigation for physiologic as well as pathophysiologic states.

Immunoassay-Based Diagnostic Point-of-Care Technology for Oral Specimen

We have outlined our progress in developing a novel point-of-care platform to quantify micro-organisms causing dental infections and/or inflammatory markers reflecting an oral disease status. This system is based on a sandwich immunoassay technology known as ABICAP (Antibody Immuno Column for Analytical Processes) using poly-horseradish peroxidase conjugates. This assay enabled us to quantify 500 colony-forming units of Streptococcus sobrinus per milliliter of saliva. The platform allows rapid and convenient performance chairside of such tests by a dentist or dental hygienist within 20 minutes at the dental office.

Determining the binding affinities of phenolic compounds to proteins by quenching of the intrinsic tryptophan fluorescence

The noncovalent binding of selected phenolic compounds (chlorogenic-, ferulic-, gallic acid, quercetin, rutin, and isoquercetin) to proteins (HSA, BSA, soy glycinin, and lysozyme) was studied by an indirect method applying the quenching of intrinsic tryptophan fluorescence. From the data obtained, the binding constants were calculated by nonlinear regression (one site binding; y = Bx/k + x). It has been reported that tannins inhibit human salivary amylase and that these complexes may reduce the development of cariogenic plaques. Further, amylase contains two tryptophan residues in its active site. Therefore, in a second part of the study involving 31 human subjects, evidence was sought for noncovalent interactions between the phenols of green tea and saliva proteins as measured by the fluorescence intensity. Amylase activity was determined before and after the addition of green tea to saliva of 31 subjects. Forty percent of the subjects showed an increase in amylase activity contrary to studies reporting only a decrease in activity. The interactions of tannin with amylase result in a decrease of its activity. It still remains to be elucidated why amylase does not react uniformly under conditions of applying green tea to saliva. Further, in terms of using phenols as caries inhibitors this finding should be of importance.