Rapid and simple detection of eight major periodontal pathogens by the loop-mediated isothermal amplification method

Evaluation of loop-mediated isothermal amplification method for efficient detection of the periodontopathic bacteria Porphyromonas gingivalis

Background

Periodontitis is a multifactorial, polymicrobial oral inflammatory illness brought on by oral pathogens. Porphyromonas gingivalis is a Gram-negative, obligatory anaerobic, black-pigmented coccobacillus and is regarded as a primary etiological factor in the progression of periodontitis. Rapid, highly senstitive and specific detection methods are emerging. The present study aimed to evaluate the loop-mediated isothermal amplification (LAMP) technique for efficiently detecting P. gingivalis from subgingival plaque samples of chronic periodontitis patients.

Materials and Methods

This study included 50 subgingival plaque samples from patients suffering from chronic periodontitis. The DNA (Deoxyribonucleic acid) was extracted by the "modified proteinase K" method. A set of six primers, targeting the pepO gene of P. gingivalis, was used for conducting LAMP. The amplification was visualized by naked-eye detection and agarose electrophoresis. Conventional polymerase chain reaction (PCR) and real-time qantitative PCR (qPCR) were carried out by targeting the 16SrRNA (16S ribosomal ribonucleic acid) gene of P. gingivalis.

Results

The results showed that LAMP detected P. gingivalis in 40 out of 50 samples (80%). Whereas, qPCR and conventional PCR technique detected P. gingivalis in 38 (76%) and 33 (66%) samples respectively. The sensitivity and specificity of the LAMP method were 94.87% and 90.90%, respectively. With qPCR, the sensitivity and specificity were found to be 92.30% and 81.81%, respectively, whereas, with conventional PCR, it was found to be 76.92% and 72.72%, respectively.

Conclusion

LAMP is an efficient technique for quick, accurate, and reliable identification of P. gingivalis from subgingival plaque samples. The technique needs to be validated analytically, and further studies can be conducted by taking saliva and/or gingival crevicular fluid samples from periodontitis patients.

Selective and easy detection of the Porphyromonas gingivalis fimA type II and IV genes by loop-mediated isothermal amplification

Porphyromonas gingivalis fimbrillin (fimA) type II and IV, the definitive factors for periodontitis, are also found to be associated with systemic diseases. To detect the fimA type II and IV genes easily and rapidly, we used the loop-mediated isothermal amplification (LAMP) method. The LAMP method showed high specificity as DNA from the P. gingivalis HW24D1 strain could only be amplified by the type II-specific primers and that from the W83 strain could only be amplified by the type IV-specific primers. Pathogens, namely, Streptococcus sobrinus, S. mutans, and Candida species, lack the type II and IV genes, and hence, were not detected by the LAMP reaction. Both bacterial cells and purified DNA could be used in the LAMP reaction. The LAMP reaction was highly sensitive and both type II and type IV genes could be detected in 1000 DNA molecules. In the bacterial suspensions of HW24D1 and W83 strains, type II and type IV genes, respectively, could be detected in 100 bacterial cells. We examined the type II and type IV genes in the dental plaques from 22 P. gingivalis-positive patients using the LAMP method. Only one person was found to be positive for the type II gene (4.5%). For the type IV gene, 3 positive cases (13.6%) were identified. Moreover, type II and type IV genes could be detected simultaneously using a multiplex amplification primer of fimA type II and type IV, under visible light. Thus, we established a selective and easy method to detect P. gingivalis fimA type II and IV genes using LAMP.

The Loop-Mediated Isothermal Amplification Technique in Periodontal Diagnostics: A Systematic Review

The course of periodontal disease is affected by many factors; however, the most significant are the dysbiotic microflora, showing different pathogenicity levels. Rapid colonization in the subgingival environment can radically change the clinical state of the periodontium. This systematic review aims to present an innovative technique of loop-mediated isothermal amplification for rapid panel identification of bacteria in periodontal diseases. The decisive advantage of the loop-mediated isothermal amplification (LAMP) technique in relation to molecular methods based on the identification of nucleic acids (such as polymerase chain reaction (PCR or qPCR) is the ability to determine more pathogens simultaneously, as well as with higher sensitivity. In comparison with classical microbiological seeding techniques, the use of the LAMP method shortens a few days waiting time to a few minutes, reducing the time necessary to identify the species and determine the number of microorganisms. The LAMP technology requires only a small hardware base; hence it is possible to use it in outpatient settings. The developed technique provides the possibility of almost immediate assessment of periodontal status and, above all, risk assessment of complications during the treatment (uncontrolled spread of inflammation), which can certainly be of key importance in clinical work.

Putative periodontopathic bacteria and herpes viruses interactions in the subgingival plaque of patients with aggressive periodontitis and healthy controls

The microbial profile of aggressive periodontitis patients is considered to be complex with variations among populations in different geographical areas. The aim of this study was to assess the presences of 4 putative periodontopathic bacteria (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) and 2 periodontal herpes viruses (Epstein-Barr virus type 1 [EBV-1] and human cytomegalovirus [HMCV]) in subgingival plaque of Sudanese subjects with aggressive periodontitis and healthy controls. The study group consisted of 34 subjects, 17 aggressive periodontitis patients and 17 periodontally healthy controls (14-19 years of age). Pooled subgingival plaque samples were collected and analyzed for detection of bacteria and viruses using loop-mediated isothermal amplification. Prevalence of subgingival A. actinomycetemcomitans, HCMV, and P. gingivalis were significantly higher among aggressive periodontitis patients than periodontally healthy controls. Coinfection with A. actinomycetemcomitans, HCMV, and/or EBV-1 was restricted to the cases. Increased risk of aggressive periodontitis was the highest when A. actinomycetemcomitans was detected together with EBV-1 (OD 49.0, 95% CI [2.5, 948.7], p = .01) and HCMV (OD 39.1, 95% CI [2.0, 754.6], p = .02). In Sudanese patients, A. actinomycetemcomitans and HCMV were the most associated test pathogens with aggressive periodontitis.

Introduction to Clinical Microbiology for the General Dentist

Clinical oral microbiology may help dental professionals identify infecting pathogenic species and evaluate their in vitro antimicrobial susceptibility. Saliva, dental plaque biofilms, mucosal smears, abscess aspirates, and soft tissue biopsies are sources of microorganisms for laboratory testing. Microbial-based treatment end points may help clinicians better identify patients in need of additional or altered dental therapies before the onset of clinical treatment failure, and help improve patient oral health outcomes. Microbiological testing appears particularly helpful in periodontal disease treatment planning. Further research and technological advances are likely to increase the availability and clinical utility of microbiological analysis in modern dental practice.

Development of Recombinase Polymerase Amplification Assays for Detection of Orientia tsutsugamushi or Rickettsia typhi

Sensitive, specific and rapid diagnostic tests for the detection of Orientia tsutsugamushi (O. tsutsugamushi) and Rickettsia typhi (R. typhi), the causative agents of scrub typhus and murine typhus, respectively, are necessary to accurately and promptly diagnose patients and ensure that they receive proper treatment. Recombinase polymerase amplification (RPA) assays using a lateral flow test (RPA-nfo) and real-time fluorescent detection (RPA-exo) were developed targeting the 47-kDa gene of O. tsutsugamushi or 17 kDa gene of R. typhi. The RPA assay was capable of detecting O. tsutsugamushi or R. typhi at levels comparable to that of the quantitative PCR method. Both the RPA-nfo and RPA-exo methods performed similarly with regards to sensitivity when detecting the 17 kDa gene of R. typhi. On the contrary, RPA-exo performed better than RPA-nfo in detecting the 47 kDa gene of O. tsutsugamushi. The clinical performance of the O. tsutsugamushi RPA assay was evaluated using either human patient samples or infected mouse samples. Eight out of ten PCR confirmed positives were determined positive by RPA, and all PCR confirmed negative samples were negative by RPA. Similar results were obtained for R. typhi spiked patient sera. The assays were able to differentiate O. tsutsugamushi and R. typhi from other phylogenetically related bacteria as well as mouse and human DNA. Furthermore, the RPA-nfo reaction was completed in 20 minutes at 37^oC followed by a 10 minute incubation at room temperature for development of an immunochromatographic strip. The RPA-exo reaction was completed in 20 minutes at 39^oC. The implementation of a cross contamination proof cassette to detect the RPA-nfo fluorescent amplicons provided an alternative to regular lateral flow detection strips, which are more prone to cross contamination. The RPA assays provide a highly time-efficient, sensitive and specific alternative to other methods for diagnosing scrub typhus or murine typhus.

Historically, rickettsial pathogens are among the leading causes of morbidity and mortality during military operations. Rickettsial diseases, lately, are reemerging in areas of known abundance or emerging in areas of unknown existence, posing a significant medical concern for local residents and travelers. The diseases are difficult to diagnose as they often share similar symptoms with many other diseases in the same geographical areas. Therefore, it is particularly challenging for clinicians to provide a timely and accurate diagnosis. A recombinase polymerase amplification (RPA)-based nucleic acid detection platform has been used to develop accurate, sensitive, specific, and easy-to-perform assays to detect O. tsutsugamushi or R. typhi, indicative of scrub typhus or murine typhus, respectively. These RPA assays provide similar limits of detection and specificity to that of qPCR. Unlike qPCR, they require no thermocycler and provide multiple end-point monitoring options amendable to different laboratory capabilities. This work presents an alternative assay platform for early detection of O. tsutsugamushi or R. typhi infection so that timely treatment can be prescribed in well-equipped laboratories as well as resource limited areas.