Fluorescence in situ hybridization for the identification of Treponema pallidum in tissue sections

Fluorescence In Situ Hybridization as Diagnostic Tool for Implant-associated Infections: A Pilot Study on Added Value

Implant-associated infections are a devastating complication in surgery. Especially in infections with biofilm-forming microorganisms, the identification of the causing microorganism remains a challenge. However, the classification as biofilm is not possible with conventional polymerase chain reaction or culture-based diagnostics. The aim of this study was to evaluate the additional value of fluorescence in situ hybridization (FISH) and nucleic acid amplification technique (FISHseq) to discuss a diagnostic benefit of the culture-independent methods and to map spatial organization of pathogens and microbial biofilms in wounds.

Methods

In total, 118 tissue samples from 60 patients with clinically suspected implant-associated infections (n = 32 joint replacements, n = 24 open reduction and internal fixation, n = 4 projectiles) were analyzed using classic microbiological culture and culture-independent FISH in combination with polymerase chain reaction and sequencing (FISHseq).

Results

In 56 of 60 wounds, FISHseq achieved an added value. FISHseq confirmed the result of cultural microbiological examinations in 41 of the 60 wounds. In 12 wounds, one or more additional pathogens were detected by FISHseq. FISHseq could show that the bacteria initially detected by culture corresponded to a contamination in three wounds and could exclude that the identified commensal pathogens were a contamination in four other wounds. In five wounds, a nonplanktonic bacterial life form was detected.

Conclusions

The study revealed that FISHseq gives additional diagnostic information, including therapy-relevant findings that were missed by culture. In addition, nonplanktonic bacterial life forms could also be detected with FISHseq, albeit less frequently than previously indicated.

Application of Fluorescence In Situ Hybridization (FISH) in Oral Microbial Detection

Varieties of microorganisms reside in the oral cavity contributing to the occurrence and development of microbes associated with oral diseases; however, the distribution and in situ abundance in the biofilm are still unclear. In order to promote the understanding of the ecosystem of oral microbiota and the diagnosis of oral diseases, it is necessary to monitor and compare the oral microorganisms from different niches of the oral cavity in situ. The fluorescence in situ hybridization (FISH) has proven to be a powerful tool for representing the status of oral microorganisms in the oral cavity. FISH is one of the most routinely used cytochemical techniques for genetic detection, identification, and localization by a fluorescently labeled nucleic acid probe, which can hybridize with targeted nucleic acid sequences. It has the advantages of rapidity, safety, high sensitivity, and specificity. FISH allows the identification and quantification of different oral microorganisms simultaneously. It can also visualize microorganisms by combining with other molecular biology technologies to represent the distribution of each microbial community in the oral biofilm. In this review, we summarized and discussed the development of FISH technology and the application of FISH in oral disease diagnosis and oral ecosystem research, highlighted its advantages in oral microbiology, listed the existing problems, and provided suggestions for future development..

Strategies for successful designing of immunocontraceptive vaccines and recent updates in vaccine development against sexually transmitted infections - A Review

Background

Objective

Methods

Results

Conclusion

Molecular diagnostic of syphilis

Syphilis is a sexually transmitted infection caused by Treponema pallidum subsp. pallidum with an increasing incidence in Spain and in the rest of the world. Diagnosis is based mainly on serology, since direct diagnosis by dark field microscopy presents difficulties that limit its widespread use. Molecular biology techniques can be a useful tool for diagnosis in primary and secondary syphilis, although not all types of samples show the same behaviour. These techniques are also useful for the diagnosis of congenital syphilis. They are not recommended, however, for neurosyphilis, due to the low sensitivity of polymerase chain reaction in cerebrospinal fluid. These techniques have been used to study the controversial origin of syphilis, and, through the enhanced Centers for Disease Control method, to perform typing, which helps to elucidate the epidemiology of this infection. Finally, molecular techniques can detect mutations related to macrolide resistance, which are present in a very high percentage of infections.

Quality Control in Diagnostic Fluorescence In Situ Hybridization (FISH) in Microbiology

This overview addresses fluorescence in situ hybridization (FISH) in a diagnostic microbiology setting with its associated problems and pitfalls and how to control them, but also the advantages and opportunities the method offers. This article focuses mainly on diagnostic FISH assays on tissue sections and on techniques and experiences in our laboratory. FISH in a routine diagnostic setting in microbiology requires strict quality control measures to ensure consistent high-quality and reliable assay results. Here, for the first time, we define quality control requirements for microbiological diagnostic FISH applications and discuss their impact and possible future developments of the FISH technique for infection diagnostics. We focus on diagnosis of biofilm-associated infections including infective endocarditis, oral biofilms, and device-associated infections as well as infections due to fastidious or yet uncultured microorganisms like Treponema spp., Tropheryma whipplei, Bartonella, Coxiella burnetii, or Brachyspira.

2020 European guideline on the management of syphilis

The 2020 edition of the European guideline on the management of syphilis is an update of the 2014 edition. Main modifications and updates include: -The ongoing epidemics of early syphilis in Europe, particularly in men who have sex with men (MSM) -The development of dual treponemal and non-treponemal point-of-care (POC) tests -The progress in non-treponemal test (NTT) automatization -The regular episodic shortage of benzathine penicillin G (BPG) in some European countries -The exclusion of azithromycin as an alternative treatment at any stage of syphilis -The pre-exposure or immediate post-exposure prophylaxis with doxycycline in populations at high risk of acquiring syphilis.

Clinical Utility of PNA-FISH for Burn Wound Diagnostics: A Noninvasive, Culture-Independent Technique for Rapid Identification of Pathogenic Organisms in Burn Wounds

Burn injury results in an immediate compromised skin state, which puts the affected patient at an immediate risk for infection, including sepsis. For burn patients that develop infections, it is critical to rapidly identify the etiology so that an appropriate treatment can be administered. Current clinical standards rely heavily on culture-based methods for local and systemic infection testing, which can often take days to complete. While more advanced methods (ie, MALDI or NAAT) have improved turnaround times, they may still suffer from either the need for pure culture or sensitivity and specificity issues. Peptide nucleic acid fluorescent in situ hybridization (PNA-FISH) offers a way to reduce this time from days to hours and provide species-specific identification. While PNA-FISH has had great utility in research, its use in clinical microbiology diagnostics has been minimal (including burn wound diagnostics). This work describes a nonculture-based identification technique using commercial available U.S. FDA-approved PNA-FISH probes for the identification of common clinical pathogens, Pseudomonas aeruginosa and Staphylococcus aureus, present in burn wound infections. Additionally, calcofluor white was included for identification of Candida albicans. All three pathogens were identified from a tri-species infected deep-partial thickness rat burn wound model. These species were clearly identifiable in swab and tissue samples that were collected, with minimal autofluorescence from any species. Although autofluorescence of the tissue was present, it did not interfere or was otherwise minimized through sample preparation and analysis. The methodology developed was done so with patient care and diagnostic laboratories in mind that it might be easily transferred to the clinical setting.

Application of molecular tools to elucidate the microbiota of seafood

The aim of this review is to present the methodologies currently applied to identify microbiota and pathogens transmitted to humans through seafood consumption, focusing on molecular techniques and pointing out their importance, advantages, disadvantages and applicability. Knowledge of available techniques allows researchers to identify which technique best fits their expectations. With such discernment, it will be possible to infer which disadvantages will be present and, therefore, not interfering with the final result. Two methodologies can be employed for this purpose, dependent and independent cultures. However, the dependent culture has certain limitations that can be solved through the independent cultivation techniques, such as PCR, PFGE and NGS, especially through the sequencing of the 16S rRNA region, providing a complete view of microbial diversity. These have revolutionized microbiological knowledge, mainly because they allow for the identification of uncultivable micro-organisms, which represent a substantial portion of total micro-organisms, making it possible to elucidate not yet described taxa which may display pathogenic potential, besides quantifying microbial communities, microbiota genetics, translated proteins and produced metabolites. In addition, transcriptomic and metabolomic techniques also allow for the evaluation of possible impacts that microbial communities may create in their environment, as well as the determination of potential pathogenicity to humans.

Microbiological diagnosis of device-related biofilm infections

Medical device-related infections cause undue patient distress, increased morbidity and mortality and pose a huge financial burden on healthcare services. The pathogens are frequently distributed heterogeneously in biofilms, which can persist without being effectively cleared by host immune defenses and antibiotic therapy. At present, there is no 'gold standard' available to reveal the presence of device-related biofilm infections. However, adequate sample collection and logistics, standardised diagnostic methods, and interpretation of results by experienced personnel are important steps in efficient diagnosis and treatment of these infections. The focus of this mini review is on prosthethic joint and cardiovascular implantable device infections, which exemplify permanent devices that are placed in a sterile body site. These device-related infections represent some of the most challenging in terms of both diagnosis and treatment.

Distribution and phylogeny of Brachyspira spp. in human intestinal spirochetosis revealed by FISH and 16S rRNA-gene analysis

During six years as German National Consultant Laboratory for Spirochetes we investigated 149 intestinal biopsies from 91 patients, which were histopathologically diagnosed with human intestinal spirochetosis (HIS), using fluorescence in situ hybridization (FISH) combined with 16S rRNA gene PCR and sequencing. Aim of this study was to complement histopathological findings with FISH and PCR for definite diagnosis and species identification of the causative pathogens. HIS is characterized by colonization of the colonic mucosa of the human distal intestinal tract by Brachyspira spp. Microbiological diagnosis of HIS is not performed, because of the fastidious nature and slow growth of Brachyspira spp. in culture. In clinical practice, diagnosis of HIS relies solely on histopathology without differentiation of the spirochetes. We used a previously described FISH probe to detect and identify Brachyspira spp. in histological gut biopsies. FISH allowed rapid visualization and identification of Brachyspira spp. in 77 patients. In most cases, the bright FISH signal already allowed rapid localization of Brachyspira spp. at 400× magnification. By sequencing, 53 cases could be assigned to the B. aalborgi lineage including "B. ibaraki" and "B. hominis", and 23 cases to B. pilosicoli. One case showed mixed colonization. The cases reported here reaffirm all major HIS Brachyspira spp. clusters already described. However, the phylogenetic diversity seems to be even greater than previously reported. In 14 cases, we could not confirm HIS by either FISH or PCR, but found colonization of the epithelium by rods and cocci, indicating misdiagnosis by histopathology. FISH in combination with molecular identification by 16S rRNA gene sequencing has proved to be a valuable addition to histopathology. It provides definite diagnosis of HIS and allows insights into phylogeny and distribution of Brachyspira spp. HIS should be considered as a differential diagnosis in diarrhea of unknown origin, particularly in patients from risk groups (e.g. patients with colonic adenomas, inflammatory polyps, inflammatory bowel disease or HIV infection and in men who have sex with men).

Fluorescence in situ hybridization (FISH) in the microbiological diagnostic routine laboratory: a review

Early identification of microbial pathogens is essential for rational and conservative antibiotic use especially in the case of known regional resistance patterns. Here, we describe fluorescence in situ hybridization (FISH) as one of the rapid methods for easy identification of microbial pathogens, and its advantages and disadvantages for the diagnosis of pathogens in human infections in the laboratory diagnostic routine. Binding of short fluorescence-labeled DNA or nucleic acid-mimicking PNA probes to ribosomes of infectious agents with consecutive analysis by fluorescence microscopy allows identification of bacterial and eukaryotic pathogens at genus or species level. FISH analysis leads to immediate differentiation of infectious agents without delay due to the need for microbial culture. As a microscopic technique, FISH has the unique potential to provide information about spatial resolution, morphology and identification of key pathogens in mixed species samples. On-going automation and commercialization of the FISH procedure has led to significant shortening of the time-to-result and increased test reliability. FISH is a useful tool for the rapid initial identification of microbial pathogens, even from primary materials. Among the rapidly developing alternative techniques, FISH serves as a bridging technology between microscopy, microbial culture, biochemical identification and molecular diagnostic procedures.

Vaccine development for syphilis

INTRODUCTION

Syphilis, caused by the spirochete Treponema pallidum subspecies pallidum, continues to be a globally prevalent disease despite remaining susceptible to penicillin treatment. Syphilis vaccine development is a viable preventative approach that will serve to complement public health-oriented syphilis prevention, screening and treatment initiatives to deliver a two-pronged approach to stemming disease spread worldwide. Areas covered: This article provides an overview of the need for development of a syphilis vaccine, summarizes significant information that has been garnered from prior syphilis vaccine studies, discusses the critical aspects of infection that would have to be targeted by a syphilis vaccine, and presents the current understanding within the field of the correlates of protection needed to be achieved through vaccination. Expert commentary: Syphilis vaccine development should be considered a priority by industry, regulatory and funding agencies, and should be appropriately promoted and supported.