Non-cultural detection and molecular genotyping of Neisseria gonorrhoeae from a piece of clothing

Applications of microbiology to different forensic scenarios - A narrative review

In contrast to other forensic disciplines, forensic microbiology is still too often considered a "side activity" and is not able to make a real and concrete contribution to forensic investigations. Indeed, the various application aspects of this discipline still remain a niche activity and, as a result, microbiological investigations are often omitted or only approximated, in part due to poor report in the literature. However, in certain situations, forensic microbiology can prove to be extremely effective, if not crucial, when all other disciplines fail. Precisely because microorganisms can represent forensic evidence, in this narrative review all the major pathological forensic applications described in the literature have been presented. The goal of our review is to highlight the versatility and transversality of microbiology in forensic science and to provide a comprehensive source of literature to refer to when needed.

Integrating the human microbiome in the forensic toolkit: Current bottlenecks and future solutions

Over the last few years, advances in massively parallel sequencing technologies (also referred to next generation sequencing) and bioinformatics analysis tools have boosted our knowledge on the human microbiome. Such insights have brought new perspectives and possibilities to apply human microbiome analysis in many areas, particularly in medicine. In the forensic field, the use of microbial DNA obtained from human materials is still in its infancy but has been suggested as a potential alternative in situations when other human (non-microbial) approaches present limitations. More specifically, DNA analysis of a wide variety of microorganisms that live in and on the human body offers promises to answer various forensically relevant questions, such as post-mortem interval estimation, individual identification, and tissue/body fluid identification, among others. However, human microbiome analysis currently faces significant challenges that need to be considered and overcome via future forensically oriented human microbiome research to provide the necessary solutions. In this perspective article, we discuss the most relevant biological, technical and data-related issues and propose future solutions that will pave the way towards the integration of human microbiome analysis in the forensic toolkit.

Culture-free genotyping of Neisseria gonorrhoeae revealed distinct strains at different anatomical sites in a quarter of patients, the Netherlands, 2012 to 2016

BackgroundGenotyping of Neisseria gonorrhoeae (NG) is essential for surveillance to monitor NG transmission and dissemination of resistant strains. Current genotyping methods rely on bacterial culture which frequently fails.AimOur aim was to develop a culture-free genotyping method that is compatible with the widely used N. gonorrhoeae multi-antigen sequence typing (NG-MAST) database, which facilitates genotyping of NG detected at separate anatomical sites in individual patients.MethodsSpecific primers for both PCR targets porB and tbpB were designed and technically validated by assessing the analytical sensitivity, cross-reactivity with 32 non-gonoccocal Neisseria species, and concordance with NG-MAST. Clinical application was assessed on 205 paired samples from concurrent NG infections at different anatomical sites of 98 patients (81 men who have sex with men and 17 women) visiting our sexually transmitted infections clinic.ResultsTyping could be consistently performed on samples with a PCR quantification cycle (Cq) value <35. Furthermore, the method showed no cross-reactivity and was concordant with NG-MAST. Culture-free NG-MAST improved the typing rate from 62% (59/95) for cultured samples to 94% (89/95) compared with culture-dependent NG-MAST. Paired samples of 80 of 98 patients were genotyped, revealing distinct NG strains in separate anatomical sites in 25% (20/80) of the patients.ConclusionsThis NG-specific genotyping method can improve NG surveillance as it facilitates genotyping of non-culturable and extra-genital samples. Furthermore, 25% of patients were infected with multiple NG strains, which is missed in current culture-dependent surveillance. Including non-culturable and concurrent NG infections in surveillance informs actions on dissemination of multidrug-resistant NG strains.

The use of current genotyping assay methods for Neisseria gonorrhoeae

The review deals with up-to-date genotyping assay methods of Neisseria gonorrhoeae. The review covers the characteristics and features of each method, application areas of genotyping assay of Neisseria gonorrhoeae. The methods described enable to upgrade the diagnostication of gonococcal infection, predict its antibiotic resistance, trace the contagion and channels of the infection as well as study the processes of molecular evolution of the microorganism. Information obtained based on up-to-date N. gonorrhoeae genotyping assay methods can be used in developing the reproductive health strategy of the population.

Molecular epidemiology of Neisseria gonorrhoeae using multi-antigen sequence typing and pulse-field gel electrophoresis in highly endemic Western Australian populations

Background

The remote and indigenous populations of Western Australia (WA) have one of the highest notification rates of gonorrhoea in the world. Despite this, the low rate of antimicrobial resistance in Neisseria gonorrhoeae from these regions permits the use of amoxycillin as empirical therapy. We describe the first molecular epidemiological study of gonococci isolated from this population using two different typing platforms.

Methods

Pulse-field gel electrophoresis (PFGE), Neisseria gonorrhoeae multi-antigen sequence typing (NG-MAST) and antimicrobial susceptibility tests were performed on 128 consecutive N. gonorrhoeae isolates cultured between January 2011 and December 2013. To highlight clusters isolates were evaluated based on their tbpB sequence types.

Results

No predominant NG-MAST or PFGE types were found. A total of 67 distinct PFGE pulsotypes were identified amongst the 128 isolates in this study with 20 PFGE pulsotypes representing 78 isolates. A total of 59 NG-MAST sequence types were found, represented by 45 porB alleles and 28 tbpB alleles with 13 tbpB genomogroups from 45 NG-MAST sequence types. TbpB genomogroup 29, represented by 45 isolates, was by far the most common genomogroup overall.

Conclusions

Results from this study suggest that gonococcal epidemiology in WA is quite different between remote regions and major population centres and, in some cases, geographically restricted. It is likely that isolates originating from endemic regions of WA mostly represent independent, small sexual networks with an infrequent interchange between other communities and regions. Given the high rate of antimicrobial resistance elsewhere in Australia, ongoing surveillance is essential to ensure the enduring efficacy of amoxycillin empiric use in the remote regions of WA.

The usefulness of Neisseria gonorrhoeae strain typing by Pulse-Field Gel Electrophoresis (PFGE) and DNA detection as the forensic evidence in child sexual abuse cases: a case series

Diagnosis of alleged child sexual abuse can be made from history in conjunction with physical examination, psychosocial evaluation, and laboratory investigations. Sexually transmitted infection associated with sexual abuse is found in 5 % of the victims, with Neisseria gonorrhoeae being the most common organism. Identification of sexually transmitted disease, particularly N. gonorrhoeae infection, can be useful for the diagnosis of sexual abuse and thus, the initiation of the child protection process. Polymerase Chain Reaction (PCR) is a newer diagnostic assay with a higher sensitivity compared with conventional culture method. In addition, N. gonorrhoeae strain typing can also be used to identify the abuser. In this case series, we present the application of N. gonorrhoeae strain typing (PFGE technique) to identify the abuser, and the confirmation of gonococcal vaginitis by PCR technique.

Review and international recommendation of methods for typing neisseria gonorrhoeae isolates and their implications for improved knowledge of gonococcal epidemiology, treatment, and biology

Gonorrhea, which may become untreatable due to multiple resistance to available antibiotics, remains a public health problem worldwide. Precise methods for typing Neisseria gonorrhoeae, together with epidemiological information, are crucial for an enhanced understanding regarding issues involving epidemiology, test of cure and contact tracing, identifying core groups and risk behaviors, and recommending effective antimicrobial treatment, control, and preventive measures. This review evaluates methods for typing N. gonorrhoeae isolates and recommends various methods for different situations. Phenotypic typing methods, as well as some now-outdated DNA-based methods, have limited usefulness in differentiating between strains of N. gonorrhoeae. Genotypic methods based on DNA sequencing are preferred, and the selection of the appropriate genotypic method should be guided by its performance characteristics and whether short-term epidemiology (microepidemiology) or long-term and/or global epidemiology (macroepidemiology) matters are being investigated. Currently, for microepidemiological questions, the best methods for fast, objective, portable, highly discriminatory, reproducible, typeable, and high-throughput characterization are N. gonorrhoeae multiantigen sequence typing (NG-MAST) or full- or extended-length porB gene sequencing. However, pulsed-field gel electrophoresis (PFGE) and Opa typing can be valuable in specific situations, i.e., extreme microepidemiology, despite their limitations. For macroepidemiological studies and phylogenetic studies, DNA sequencing of chromosomal housekeeping genes, such as multilocus sequence typing (MLST), provides a more nuanced understanding.

Molecular surveillance of clinical Neisseria gonorrhoeae isolates in Russia

The choice of adequate methods for epidemiological purposes remains a challenging problem in Neisseria gonorrhoeae molecular monitoring. In this study, the collection of geographically unrelated gonococci (n = 103) isolated in Russian clinics was comparably tested by (i) a traditional serotyping scheme, (ii) por typing, (iii) Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST), and (iv) multilocus sequence typing (MLST). It is shown that, according to sequencing data, a third of the strains carried new porB1 alleles, as well as tbpB ones, and more than half of the samples had new sequence types (STs) as determined by NG-MAST or MLST. The discriminatory power for each typing method was calculated by using the Hunter-Gaston discriminatory index, D. Commonly, modern nucleic acid-based typing methods (por typing, NG-MAST, and MLST) appeared to be more efficient than the classical serotyping scheme. While the traditional serotyping gave a D value of 0.82, the por typing, NG-MAST, and MLST approaches yielded D values of 0.97, 0.98, and 0.91, respectively. Each typing technique revealed the distribution of gonococci slightly correlated with their geographical sources. However, only the MLST method STs were highly associated with certain phenotypes. Although ST1594, ST1892, and ST6720 were typical for susceptible gonococci, ST1901 and ST6716 were undoubtedly associated with a multidrug-resistant phenotype. We conclude that every tested nucleic acid-based typing method is suitable for N. gonorrhoeae molecular surveillance. However, the MLST method seems to serve large-scale epidemiological purposes, whereas the NG-MAST and por typing approaches are more appropriate for the investigation of local outbreaks.

Medical and legal implications of testing for sexually transmitted infections in children

Testing for sexually transmitted infections (STIs) in children presents a number of problems for the practitioner that are not usually faced when testing adults for the same infections. The identification of an STI in a child can have, in addition to medical implications, serious legal implications. The presence of an STI is often used to support the presence or allegations of sexual abuse, and conversely, the identification of an STI in a child will prompt an investigation of possible abuse. The purpose of this paper is to review the epidemiology of child sexual abuse, including the epidemiology of major STIs including Neisseria gonorrhoeae, Chlamydia trachomatis, syphilis, herpes simplex virus (HSV), Trichomonas vaginalis, and human papillomavirus, and the current recommendations for diagnostic testing in this population.

Design of a multiplex PCR assay for the simultaneous detection and confirmation of Neisseria gonorrhoeae

OBJECTIVES

To improve the detection of Neisseria gonorrhoeae by designing a multiplex PCR assay using two N gonorrhoeae-specific genes as targets, thereby providing detection and confirmation of a positive result simultaneously.

METHODS

PCR primers were designed to detect two N gonorrhoeae genes, namely porA and pgi1. Primers for an internal control targeting the ompW gene of Vibrio cholerae were also designed and incorporated in the assay. The DNA of 45 clinical isolates including 33 N gonorrhoeae isolates, seven non-gonococcal Neisseria species, and five non-Neisseria species was tested using the multiplex PCR assay.

RESULTS

All 33 N gonorrhoeae isolates were successfully detected by the assay and none of the non-gonococcal isolates was detected. The assay showed a sensitivity and specificity of 100%, and a limit of detection of 1.25 ng of DNA.

CONCLUSION

This multiplex PCR assay offers a sensitive and specific assay suitable for the detection of N gonorrhoeae, and offers real potential for diagnostic use.

Chain of evidence in sexual assault cases

Chain of evidence (COE) sampling is a legal concept demonstrating the journey of a sample from origin to court. Positive sexually transmitted infection (STI) results may have importance in criminal proceedings and require a demonstrated COE for them to be used as admissible evidence. A retrospective case-notes review of female sexual assault patients was carried out to review COE sampling in two clinics. Three hundred and eighteen patients underwent sexual health screening and COE sampling was indicated in 58 (18%). COE sampling was carried out in 44 (92%) of 48 indicated cases at the Haven (a dedicated sexual assault centre) and five (50%) of 10 at the Ambrose King Centre (a sexual health clinic). COE protocols should be in place in both sexual assault referral centres and sexual health clinics. In specialist clinics, with well-established guidelines and trained dedicated staff, COE sampling standards can be achieved.

Molecular subtyping of Treponema pallidum subsp. pallidum in Lisbon, Portugal

The objectives of this study were to evaluate the reproducibility of a molecular method for the subtyping of Treponema pallidum subsp. pallidum and to discriminate strains of this microorganism from strains from patients with syphilis. We studied 212 specimens from a total of 82 patients with different stages of syphilis (14 primary, 7 secondary and 61 latent syphilis). The specimens were distributed as follows: genital ulcers (n = 9), skin and mucosal lesions (n = 7), blood (n = 82), plasma (n = 82), and ear lobe scrapings (n = 32). The samples were assayed by a PCR technique to amplify a segment of the polymerase gene I (polA). Positive samples were typed on the basis of the analysis of two variable genes, tpr and arp. Sixty-two of the 90 samples positive for polA yielded typeable Treponema pallidum DNA. All skin lesions in which T. pallidum was identified (six of six [100%]) were found to contain enough DNA for typing of the organism. It was also possible to type DNA from 7/9 (77.7%) genital ulcer samples, 13/22 (59.1%) blood samples, 20/32 (62.5%) plasma samples, and 16/21 (76.2%) ear lobe scrapings. The same subtype was identified in all samples from the same patient. Five molecular subtypes (subtypes 10a, 14a, 14c, 14f, and 14g) were identified, with the most frequently found subtype being subtype 14a and the least frequently found subtype being subtype 10a. In conclusion, the subtyping technique used in this study seems to have good reproducibility. To our knowledge, subtype 10a was identified for the first time. Further studies are needed to explain the presence of this subtype in Portugal, namely, its relationship to the Treponema pallidum strains circulating in the African countries where Portuguese is spoken.