Re-emerging and newly recognized sexually transmitted infections: Can prior experiences shed light on future identification and control?

Pushing boundaries: mechanisms enabling bacterial pathogens to spread between cells

For multiple intracellular bacterial pathogens, the ability to spread directly into adjacent epithelial cells is an essential step for disease in humans. For pathogens such as Shigella, Listeria, Rickettsia, and Burkholderia, this intercellular movement frequently requires the pathogens to manipulate the host actin cytoskeleton and deform the plasma membrane into structures known as protrusions, which extend into neighboring cells. The protrusion is then typically resolved into a double-membrane vacuole (DMV) from which the pathogen quickly escapes into the cytosol, where additional rounds of intercellular spread occur. Significant progress over the last few years has begun to define the mechanisms by which intracellular bacterial pathogens spread. This review highlights the interactions of bacterial and host factors that drive mechanisms required for intercellular spread with a focus on how protrusion structures form and resolve.

Enteric Infections in Men Who Have Sex With Men

BACKGROUND

Enteric pathogens are often associated with exposure to food, water, animals, and feces from infected individuals. However, in sexual networks of men who have sex with men (MSM), transmission of enteric pathogens may occur during direct or indirect oral-anal contact.

METHODS

We performed a scoping review of the literature for studies prior to July 2019 with key terms for gastrointestinal syndromes ("proctitis," "enteritis," "proctocolitis"), enteric pathogens or sexually transmitted infections (STIs), and outbreaks using multiple electronic databases.

RESULTS

We identified 5861 records through database searches, bibliography reviews, and keyword searches, of which 117 references were included in the pathogen-specific reviews.

CONCLUSIONS

The strength of observational data describing enteric pathogens in MSM and possible sexual transmission of enteric pathogens varies by pathogen; however, a robust body of literature describes the sexual transmission of Campylobacter, Giardia lamblia, and Shigella (particularly antimicrobial-resistant strains) in sexual networks of MSM. Providers are encouraged to consider enteritis or proctocolitis in MSM as possibly having been sexually transmitted and encourage targeted STI testing. Risk/harm reduction and prevention messages should also be incorporated, though there is an acknowledged paucity of evidence with regards to effective strategies. Further research is needed to understand the transmission and prevention of enteric pathogens in MSM.

Emerging and re-emerging sexually transmitted diseases: A review of epidemiological evidences

Substantial increase in the outbreaks of sexually transmitted infections (STIs) and associated mortalities have raised international concerns. Concurrent with the escalation of established STIs, developing epidemics and outbreaks of newly emerging sexually transmissible pathogens pose serious problems for people and added burden and challenges for public health practitioners and researchers. Importantly, most of the emerging STIs are frequently found among vulnerable groups, such as men having sex with men and human immunodeficiency virus patients, which may result in large outbreaks in the near future. Furthermore, enhanced spread of antimicrobial resistance among these pathogens ever more limits treatment options for STIs. Thus, it is the optimal time to consider whether an infectious agent is sexually transmissible and develop treatment protocol for handling new STIs with pandemic potential. In this review, we explore emerging STIs, their current epidemiological status, and future perspective.

The serogroup B meningococcal outer membrane vesicle-based vaccine 4CMenB induces cross-species protection against Neisseria gonorrhoeae

There is a pressing need for a gonorrhea vaccine due to the high disease burden associated with gonococcal infections globally and the rapid evolution of antibiotic resistance in Neisseria gonorrhoeae (Ng). Current gonorrhea vaccine research is in the stages of antigen discovery and the identification of protective immune responses, and no vaccine has been tested in clinical trials in over 30 years. Recently, however, it was reported in a retrospective case-control study that vaccination of humans with a serogroup B Neisseria meningitidis (Nm) outer membrane vesicle (OMV) vaccine (MeNZB) was associated with reduced rates of gonorrhea. Here we directly tested the hypothesis that Nm OMVs induce cross-protection against gonorrhea in a well-characterized female mouse model of Ng genital tract infection. We found that immunization with the licensed Nm OMV-based vaccine 4CMenB (Bexsero) significantly accelerated clearance and reduced the Ng bacterial burden compared to administration of alum or PBS. Serum IgG and vaginal IgA and IgG that cross-reacted with Ng OMVs were induced by 4CMenB vaccination by either the subcutaneous or intraperitoneal routes. Antibodies from vaccinated mice recognized several Ng surface proteins, including PilQ, BamA, MtrE, NHBA (known to be recognized by humans), PorB, and Opa. Immune sera from both mice and humans recognized Ng PilQ and several proteins of similar apparent molecular weight, but MtrE was only recognized by mouse serum. Pooled sera from 4CMenB-immunized mice showed a 4-fold increase in serum bactericidal50 titers against the challenge strain; in contrast, no significant difference in bactericidal activity was detected when sera from 4CMenB-immunized and unimmunized subjects were compared. Our findings directly support epidemiological evidence that Nm OMVs confer cross-species protection against gonorrhea, and implicate several Ng surface antigens as potentially protective targets. Additionally, this study further defines the usefulness of murine infection model as a relevant experimental system for gonorrhea vaccine development.

Comparative analysis of Bacterial Vaginosis microbiota among pregnant and non-pregnant females and isolation of phages against Enterococcus faecalis, Enterococcus faecium, and Shigella flexneri strains

BACKGROUND AND OBJECTIVES

Bacterial vaginosis (BV) is the most common vaginal infection in women of reproductive age. It shifts the paradigms of the vagina from healthy, beneficial microbiota to facultative and strict anaerobes. BV remains one of the most arduous and controversial challenges in modern-day clinical microbiology because of its high prevalence and relapse rates. A lot of research has been carried out on it. Still, its etiology is unknown, which gave this infection global importance. The current study was designed to investigate and compare the microbiota of pregnant and non-pregnant females suffering from BV, and phages were isolated against BV microbiota.

MATERIAL AND METHODS

The samples were collected from the vagina by using a speculum, and swabs were streaked on different media to isolate bacteria. The microbiological analysis was performed by microscopy, biochemical testing, and antibiotic susceptibility was determined by using Metronidazole and Clindamycin. Furthermore, the phages were isolated and characterized against BV strains.

RESULTS AND CONCLUSION

The Gram staining showed high prevalence of Staphylococcus (36% vs. 33%), followed by Streptococcus (31% vs. 14%) and Enterococcus (7% vs. 14%) in non-pregnant and pregnant females' respectively. However, the exception was observed in non-pregnant BV positive females, who had Shigella flexneri in their samples. The antibiotic sensitivity showed Metronidazole was resistant against all BV microbiota, and Clindamycin showed susceptibility against 3 strains. Phages were isolated against three bacterial strains, i.e. E. faecalis, E. faecium, and S. flexneri. Bacterial reduction assay showed bacterial growth decreases in the presence of phage suspension, pH stability showed phages' maximum lytic activity at pH 7 for E. faecalis and E. faecium and pH 9 for S. flexneri. However, the thermal stability showed phages' highest lytic activity at 55 °C for E. faecalis, 70 °C for E. faecium, and 40 °C for S. flexneri. Phage genome isolation showed that all phages nucleic acid was DNA in nature and between 15 and 20kbp. SEM analysis showed they were circular in shape and might belong to the Podoviridae family. This study provides an understanding of pathogens involved in BV and helps the doctors to treat the patients accordingly. Furthermore, this study showed that Bacterial Vaginosis and BV secondary bacteria have associations. BV secondary microbiota is also involved in the pathogenesis of this infection, whereas bacteriophage therapy has the potential to be used as an alternative treatment to antibiotics.

Mycoplasma genitalium incidence, persistence, concordance between partners and progression: systematic review and meta-analysis

Background

Mycoplasma genitalium is increasingly seen as an emerging sexually transmitted pathogen, and has been likened to Chlamydia trachomatis, but its natural history is poorly understood. The objectives of this systematic review were to determine M. genitalium incidence, persistence, concordance between sexual partners and the risk of pelvic inflammatory disease (PID).

Methods

We searched Medline, EMBASE, LILACS, IndMed and African Index Medicus from 1 January 1981 until 17 March 2018. Two independent researchers screened studies for inclusion and extracted data. We examined results in forest plots, assessed heterogeneity and conducted meta-analysis where appropriate. Risk of bias was assessed for all studies.

Results

We screened 4634 records and included 18 studies; six (4201 women) reported on incidence, five (636 women) on persistence, 10 (1346 women and men) on concordance and three (5139 women) on PID. Incidence in women in two very highly developed countries was 1.07 per 100 person-years (95% CI 0.61 to 1.53, I² 0%). Median persistence of M. genitalium was estimated from one to three months in four studies but 15 months in one study. In 10 studies measuring M. genitalium infection status in couples, 39%–50% of male or female sexual partners of infected participants also had M. genitalium detected. In prospective studies, PID incidence was higher in women with M. genitalium than those without (risk ratio 1.73, 95% CI 0.92 to 3.28, I² 0%, two studies).

Discussion

Incidence of M. genitalium in very highly developed countries is similar to that for C. trachomatis, but concordance might be lower. Taken together with other evidence about age distribution and antimicrobial resistance in the two infections, M. genitalium is not the new chlamydia. Synthesised data about prevalence, incidence and persistence of M. genitalium infection are inconsistent. These findings can be used for mathematical modelling to investigate the dynamics of M. genitalium.

Registration numbers

CRD42015020420, CRD42015020405

Sexually transmitted infections-Research priorities for new challenges

In an Editorial, Guest Editors Nicola Low and Nathalie Broutet discuss the Collection on sexually transmitted infections in the context of research priorities in the field.