Characterisation of Neisseria gonorrhoeae in semen during urethral infection in men

Evaluation of the APTIMA Combo 2™ kit for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in frozen semen

Detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) in cryopreserved semen is crucial for screening sperm donors. The evaluation of the limit of detection (LOD) of the APTIMA Combo 2™ kit (Panther, Hologic) was performed on cryopreserved semen samples spiked with CT and NG at concentrations ranging from 1 to 106 IFU/mL or CFU/mL, respectively. The LOD was 102 IFU/mL for CT and 10 CFU/mL for NG in single infection or coinfection. An inhibitory effect of semen on amplification was highlighted. This study confirmed the performance of the APTIMA Combo 2™ kit for screening cryopreserved sperm samples before donation.

Mechanisms of host manipulation by Neisseria gonorrhoeae

Neisseria gonorrhoeae (also known as gonococcus) has been causing gonorrhoea in humans since ancient Egyptian times. Today, global gonorrhoea infections are rising at an alarming rate, in concert with an increasing number of antimicrobial-resistant strains. The gonococcus has concurrently evolved several intricate mechanisms that promote pathogenesis by evading both host immunity and defeating common therapeutic interventions. Central to these adaptations is the ability of the gonococcus to manipulate various host microenvironments upon infection. For example, the gonococcus can survive within neutrophils through direct regulation of both the oxidative burst response and maturation of the phagosome; a concerning trait given the important role neutrophils have in defending against invading pathogens. Hence, a detailed understanding of how N. gonorrhoeae exploits the human host to establish and maintain infection is crucial for combating this pathogen. This review summarizes the mechanisms behind host manipulation, with a central focus on the exploitation of host epithelial cell signaling to promote colonization and invasion of the epithelial lining, the modulation of the host immune response to evade both innate and adaptive defenses, and the manipulation of host cell death pathways to both assist colonization and combat antimicrobial activities of innate immune cells. Collectively, these pathways act in concert to enable N. gonorrhoeae to colonize and invade a wide array of host tissues, both establishing and disseminating gonococcal infection.

Bactericidal Effect of 5-Mercapto-2-nitrobenzoic Acid-Coated Silver Nanoclusters against Multidrug-Resistant Neisseria gonorrhoeae

Neisseria gonorrhoeae is among the most multidrug-resistant bacteria in circulation today, and new treatments are urgently needed. In this work, we demonstrate the ability of 5-mercapto-2-nitrobenzoic acid-coated silver nanoclusters (MNBA-AgNCs) to kill strains of Neisseria gonorrhoeae. Using an in vitro bactericidal assay, MNBA-AgNCs had been found to show significantly higher anti-gonococcal bioactivity than the antibiotics ceftriaxone and azithromycin and silver nitrate. These nanoclusters were effective against both planktonic bacteria and a gonococcal infection of human cell cultures in vitro. Treatment of human cells in vitro with MNBA-AgNCs did not induce significant release of lactate dehydrogenase, suggesting minimal cytotoxicity to eukaryotic cells. Our results suggest that MNBA-AgNCs hold great potential for topical treatment of localized gonorrhoeae.

Human Immune Responses and the Natural History of Neisseria gonorrhoeae Infection

The intimate relationship between humans and Neisseria gonorrhoeae infections span centuries, which is evidenced in case reports from studies dating back to the late 1700s and historical references that predate medical literature. N. gonorrhoeae is an exclusive human pathogen that infects the genital tract of both men and women as well as other mucosal surfaces including the oropharynx and rectum. In symptomatic infections, N. gonorrhoeae induces a robust inflammatory response at the site of infection. However, infections can also present asymptomatically complicating efforts to reduce transmission. N. gonorrhoeae infections have been effectively treated with antibiotics since their use was introduced in humans. Despite the existence of effective antibiotic treatments, N. gonorrhoeae remains one of the most common sexually transmitted pathogens and antibiotic resistant strains have arisen that limit treatment options. Development of a vaccine to prevent infection is considered a critical element of controlling this pathogen. The efforts to generate an effective gonococcal vaccine is limited by our poor understanding of the natural immunologic responses to infection. It is largely accepted that natural protective immunity to N. gonorrhoeae infections in humans does not occur or is very rare. Previous studies of the natural history of infection as well as some of the humoral and cellular immune responses to infection offer a window into the issues surrounding N. gonorrhoeae vaccine development. In this review, we summarize the current body of knowledge pertaining to human immune responses to gonococcal infections and the role of these responses in mediating protection from N. gonorrhoeae.

Selection for a CEACAM receptor-specific binding phenotype during Neisseria gonorrhoeae infection of the human genital tract

Infections by Neisseria gonorrhoeae are increasingly common, are often caused by antibiotic-resistant strains, and can result in serious and lasting sequelae, prompting the reemergence of gonococcal disease as a leading global health concern. N. gonorrhoeae is a human-restricted pathogen that primarily colonizes urogenital mucosal surfaces. Disease progression varies greatly between the sexes: men usually present with symptomatic infection characterized by a painful purulent urethral discharge, while in women, the infection is often asymptomatic, with the most severe pathology occurring when the bacteria ascend from the lower genital tract into the uterus and fallopian tubes. Classical clinical studies demonstrated that clinically infectious strains uniformly express Opa adhesins; however, their specificities were unknown at the time. While in vitro studies have since identified CEACAM proteins as the primary target of Opa proteins, the gonococcal specificity for this human family of receptors has not been addressed in the context of natural infection. In this study, we characterize a collection of low-passage-number clinical-specimen-derived N. gonorrhoeae isolates for Opa expression and assess their CEACAM-binding profiles. We report marked in vivo selection for expression of phase-variable Opa proteins that bind CEACAM1 and CEACAM5 but selection against expression of Opa variants that bind to the neutrophil-restricted decoy receptor CEACAM3. This is the first study showing phenotypic selection for distinct CEACAM-binding phenotypes in vivo, and it supports the opposing functions of CEACAMs that facilitate infection versus driving inflammation within the genital tract.

Inhibition of Neisseria gonorrhoeae epithelial cell interactions by vaginal Lactobacillus species

High levels of Lactobacillus, the dominant genus of the healthy human vaginal microbiota, have been epidemiologically linked to a reduced risk of infection following exposure to the sexually transmitted pathogen Neisseria gonorrhoeae. In this work, a cell culture model of gonococcal infection was adapted to examine the effects of lactobacilli on gonococcal interactions with endometrial epithelial cells in vitro. Precolonization of epithelial cells with Lactobacillus jensenii, Lactobacillus gasseri ATCC 33323, or L. gasseri ATCC 9857 reduced gonococcal adherence by nearly 50%. Lactobacilli also inhibited gonococcal invasion of epithelial cells by more than 60%, which was independent of the effect on adherence. Furthermore, lactobacilli were able to displace adherent gonococci from epithelial cells, suggesting that these organisms have potential as a postexposure prophylactic. Thus, vaginal lactobacilli have the ability to inhibit gonococci at two key steps of an infection, which might have a significant effect in determining whether the gonococcus will be able to successfully establish an infection following exposure in vivo.