Aminomethyl Spectinomycins as Therapeutics for Drug-Resistant Gonorrhea and Chlamydia Coinfections

Ameliorating Gonorrhea: Recent Therapeutic Adaptations and Scope to Improve its Prevailing Condition

BACKGROUND

Gonorrhea is a sexually transmitted infection (STI) caused by the bacteria Neisseria gonorrhoeae. According to recent research, the prevalence of gonorrhea has been increasing in many parts of the world, with some areas reporting high rates of antibiotic resistance. In the United States, the Centers for Disease Control and Prevention (CDC) reported that the number of reported gonorrhea cases increased by 56% between 2015 and 2019. Globally, the World Health Organization (WHO) estimated that there were 87 million new cases of gonorrhea in 2016, with the highest burden of infection in low- and middle-income countries. Research has also shown that gonorrhea is becoming increasingly resistant to conventional antibiotics, increasing the prevalence of gonorrhea. This raises concerns and challenges in disease management.

OBJECTIVES

The present review gives updated insight on the current state of the disease, challenges, and shortcomings of existing approaches along with the modern and alternative direction like vaccine development, its challenges, and scope to confront the existing state of drug resistance and increased rate of incidence. Alternative strategies like immunotherapy and phage therapy along with recent antibiotics researched for the treatment of gonorrhea.

CONCLUSION

The review provides a thorough insight into the current state of the disease and various available methods used currently and recommended by WHO. To overcome disease prevalence, various alternate therapies are coming into the limelight. However, scientists and researchers show a lack of interest in the drug development and research of gonorrhea, due to less commercial scope, lack of funding, and limited scope in the scientific scenario. These hurdles need to be overcome to meet the WHO vision of reducing gonorrhea by 90% by 2030. So, there is a need to optimize the drug therapy (optimizing dosing schedule, and precision monitoring) to reduce the chance of drug resistance. Also, there is a wide scope for drug and therapeutic system development.

Vertebrate and Invertebrate Animal and New In Vitro Models for Studying Neisseria Biology

The history of Neisseria research has involved the use of a wide variety of vertebrate and invertebrate animal models, from insects to humans. In this review, we itemise these models and describe how they have made significant contributions to understanding the pathophysiology of Neisseria infections and to the development and testing of vaccines and antimicrobials. We also look ahead, briefly, to their potential replacement by complex in vitro cellular models.

Colonization efficiency of multidrug-resistant Neisseria gonorrhoeae in a female mouse model

The rapid occurrence of gonococcal resistance to all classes of antibiotics could lead to untreatable gonorrhea. Thus, development of novel anti-Neisseria gonorrhoeae drugs is urgently needed. Neisseria gonorrhoeae FA1090 is the most used in gonococcal infection mouse models because of its natural resistance to streptomycin. Streptomycin inhibits the urogenital commensal flora that permits gonococcal colonization. However, this strain is drug-susceptible and cannot be used to investigate the efficacy of novel agents against multidrug-resistant N. gonorrhoeae. Hence, to test the in vivo efficacy of new therapeutics against N. gonorrhoeae resistant to the frontline antibiotics, azithromycin, or ceftriaxone, we constructed streptomycin-resistant mutants of N. gonorrhoeae CDC-181 (azithromycin-resistant) and WHO-X (ceftriaxone-resistant). We identified the inoculum size needed to successfully colonize mice. Both mutants, CDC-181-rpsLA128G and WHO-X-rpsLA128G, colonized the genital tract of mice for 14 days with 100% colonization observed for at least 7 days. CDC-181-rpsLA128G demonstrated better colonization of the murine genital tract compared to WHO-X-rpsLA128G. Lower inoculum of WHO-X-rpsLA128G (105 and 106 CFU) colonized mice better than higher inoculum. Overall, our results indicate that CDC-181-rpsLA128G and WHO-X-rpsLA128G can colonize the lower genital tract of mice and are suitable to be used in mouse models to investigate the efficacy of antigonococcal agents.

Molecular Mechanisms of Drug Resistance and Epidemiology of Multidrug-Resistant Variants of Neisseria gonorrhoeae

The paper presents various issues related to the increasing drug resistance of Neisseria gonorrhoeae and the occurrence and spread of multidrug-resistant clones. One of the most important is the incidence and evolution of resistance mechanisms of N. gonorrhoeae to beta-lactam antibiotics. Chromosomal resistance to penicillins and oxyimino-cephalosporins and plasmid resistance to penicillins are discussed. Chromosomal resistance is associated with the presence of mutations in the PBP2 protein, containing mosaic variants and nonmosaic amino acid substitutions in the transpeptidase domain, and their correlation with mutations in the mtrR gene and its promoter regions (the MtrCDE membrane pump repressor) and in several other genes, which together determine reduced sensitivity or resistance to ceftriaxone and cefixime. Plasmid resistance to penicillins results from the production of beta-lactamases. There are different types of beta-lactamases as well as penicillinase plasmids. In addition to resistance to beta-lactam antibiotics, the paper covers the mechanisms and occurrence of resistance to macrolides (azithromycin), fluoroquinolones and some other antibiotics. Moreover, the most important epidemiological types of multidrug-resistant N. gonorrhoeae, prevalent in specific years and regions, are discussed. Epidemiological types are defined as sequence types, clonal complexes and genogroups obtained by various typing systems such as NG-STAR, NG-MAST and MLST. New perspectives on the treatment of N. gonorrhoeae infections are also presented, including new drugs active against multidrug-resistant strains.

Auranofin exerts antibacterial activity against Neisseria gonorrhoeae in a female mouse model of genital tract infection

Neisseria gonorrhoeae has been classified by the U.S. Centers for Disease Control and Prevention as an urgent threat due to the rapid development of antibiotic resistance to currently available antibiotics. Therefore, there is an urgent need to find new antibiotics to treat gonococcal infections. In our previous study, the gold-containing drug auranofin demonstrated potent in vitro activity against clinical isolates of N. gonorrhoeae, including multidrug-resistant strains. Therefore, the aim of this study was to investigate the in vivo activity of auranofin against N. gonorrhoeae using a murine model of vaginal infection. A significant reduction in N. gonorrhoeae recovered from the vagina was observed for infected mice treated with auranofin compared to the vehicle over the course of treatment. Relative to the vehicle, after three and five days of treatment with auranofin, a 1.04 (91%) and 1.40 (96%) average log₁₀-reduction of recovered N. gonorrhoeae was observed. In conclusion, auranofin has the potential to be further investigated as a novel, safe anti-gonococcal agent to help meet the urgent need for new antimicrobial agents for N. gonorrhoeae infection.

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

Background

Objective

Methods

Results

Conclusion

Repurposing FDA-approved sulphonamide carbonic anhydrase inhibitors for treatment of Neisseria gonorrhoeae

Neisseria gonorrhoeae is a high-priority pathogen of concern due to the growing prevalence of resistance development against approved antibiotics. Herein, we report the anti-gonococcal activity of ethoxzolamide, the FDA-approved human carbonic anhydrase inhibitor. Ethoxzolamide displayed an MIC_50, against a panel of N. gonorrhoeae isolates, of 0.125 µg/mL, 16-fold more potent than acetazolamide, although both molecules exhibited almost similar potency against the gonococcal carbonic anhydrase enzyme (NgCA) in vitro. Acetazolamide displayed an inhibition constant (K_i) versus NgCA of 74 nM, while Ethoxzolamide^’s K_i was estimated to 94 nM. Therefore, the increased anti-gonococcal potency of ethoxzolamide was attributed to its increased permeability in N. gonorrhoeae as compared to that of acetazolamide. Both drugs demonstrated bacteriostatic activity against N. gonorrhoeae, exhibited post-antibiotic effects up to 10 hours, and resistance was not observed against both. Taken together, these results indicate that acetazolamide and ethoxzolamide warrant further investigation for translation into effective anti-N. gonorrhoeae agents.

Preclinical Testing of Vaccines and Therapeutics for Gonorrhea in Female Mouse Models of Lower and Upper Reproductive Tract Infection

Murine models of Neisseria gonorrhoeae lower reproductive tract infection are valuable systems for studying N. gonorrhoeae adaptation to the female host and immune responses to infection. These models have also accelerated preclinical testing of candidate therapeutic and prophylactic products against gonorrhea. However, because N. gonorrhoeae infection is restricted to the murine cervicovaginal region, there is a need for an in vivo system for translational work on N. gonorrhoeae pelvic inflammatory disease (PID). Here we discuss the need for well-characterized preclinical upper reproductive tract infection models for developing candidate products against N. gonorrhoeae PID, and report a refinement of the gonorrhea mouse model that supports sustained upper reproductive tract infection. To establish this new model for vaccine testing, we also tested the licensed meningococcal 4CMenB vaccine, which cross-protects against murine N. gonorrhoeae lower reproductive tract infection, for efficacy against N. gonorrhoeae in the endometrium and oviducts following transcervical or vaginal challenge.

Epidemiology, Treatments, and Vaccine Development for Antimicrobial-Resistant Neisseria gonorrhoeae: Current Strategies and Future Directions

Neisseria gonorrhoeae is the second most common bacterial sexually transmitted infection in the world after Chlamydia trachomatis. The pathogen has developed resistance to every antibiotic currently approved for treatment, and multidrug-resistant strains have been identified globally. The current treatment recommended by the World Health Organization is ceftriaxone and azithromycin dual therapy. However, resistance to azithromycin and ceftriaxone are increasing and treatment failures have been reported. As a result, there is a critical need to develop novel strategies for mitigating the spread of antimicrobial-resistant N. gonorrhoeae through improved diagnosis and treatment of resistant infections. Strategies that are currently being pursued include developing molecular assays to predict resistance, utilizing higher doses of ceftriaxone, repurposing older antibiotics, and developing newer agents. In addition, efforts to discover a vaccine for N. gonorrhoeae have been reignited in recent years with the cross-protectivity provided by the N. meningitidis vaccine, with several new strategies and targets. Despite the significant progress that has been made, there is still much work ahead to combat antimicrobial-resistant N. gonorrhoeae globally.

Synthesis, antibacterial action, and ribosome inhibition of deoxyspectinomycins

Spectinomycin, an aminocyclitol antibiotic, is subject to inactivation by aminoglycoside modifying enzymes (AMEs) through adenylylation or phosphorylation of the 6-hydroxy group position. In this study, the effects of deoxygenation of the 2- and 6-hydroxy group positions on the spectinomycin actinamine ring are probed to evaluate their relationship to ribosomal binding and the antimicrobial activities of spectinomycin, semisynthetic aminomethyl spectinomycins (amSPCs), and spectinamides. To generate these analogs, an improved synthesis of 6-deoxyspectinomycin was developed using the Barton deoxygenation reaction. 6-Dehydrospectinamide was also synthesized from spectinamide 4 to evaluate the H-bond acceptor character on the C-6 position. All the synthesized analogs were tested for antibacterial activity against a panel of Gram (+) and Gram (-) pathogens, plus Mycobacterium tuberculosis. The molecular contribution of the 2- and 6-hydroxy group and the aryl functionalities of all analogs were examined by measuring inhibition of ribosomal translation and molecular dynamics experiments with MM/GBSA analysis. The results of this work indicate that the 6-hydroxy group, which is the primary target of AMEs, is a required motif for antimicrobial activity in current analogs. Removal of the 6-hydroxy group could be partially rescued by offsetting ribosomal binding contributions made by the aryl side chains found in the spectinamide and amSPCs. This study builds on the knowledge of the structure-activity relationships of spectinomycin analogs and is being used to aid the design of next-generation spectinomycins.

trans-Translation inhibitors bind to a novel site on the ribosome and clear Neisseria gonorrhoeae in vivo

Bacterial ribosome rescue pathways that remove ribosomes stalled on mRNAs during translation have been proposed as novel antibiotic targets because they are essential in bacteria and are not conserved in humans. We previously reported the discovery of a family of acylaminooxadiazoles that selectively inhibit trans-translation, the main ribosome rescue pathway in bacteria. Here, we report optimization of the pharmacokinetic and antibiotic properties of the acylaminooxadiazoles, producing MBX-4132, which clears multiple-drug resistant Neisseria gonorrhoeae infection in mice after a single oral dose. Single particle cryogenic-EM studies of non-stop ribosomes show that acylaminooxadiazoles bind to a unique site near the peptidyl-transfer center and significantly alter the conformation of ribosomal protein bL27, suggesting a novel mechanism for specific inhibition of trans-translation by these molecules. These results show that trans-translation is a viable therapeutic target and reveal a new conformation within the bacterial ribosome that may be critical for ribosome rescue pathways.

Anaerobic digestion of spectinomycin mycelial residues pretreated by thermal hydrolysis: removal of spectinomycin and enhancement of biogas production

Anaerobic digestion (AD) is an effective technology to dispose antibiotic mycelial residues, but biogas production is influenced by hydrolysis rates and antibiotic residue. Herein, the effects of thermal hydrolysis pretreatment for AD of spectinomycin mycelial residues (SMRs) were investigated. The results showed that the removal ratio of spectinomycin was increased while the temperature of pretreatment was escalating. Meanwhile, thermal hydrolysis facilitated the dissolution of organic matters. However, non-biodegradable substances measured by fluorescence excitation-emission matrix accumulated and thus had an adverse influence on biogas production. Based on batch assays, the optimal pretreatment temperature for SMRs was 120 °C. The removal of spectinomycin was benefit for biogas production (increasing by 7.6%), and the overall biogas production increased by 27.6% compared with 289.90 mL gVS^-1 of untreated SMRs. The microbial community analysis revealed that spectinomycin (265 mg L^-1) might influence bacteria in the early stage of AD (first 5 days), while redundancy analysis showed that spectinomycin had a non-significant influence on community succession over the 32 days of fermentation.

The frontiers of addressing antibiotic resistance in Neisseria gonorrhoeae

The sexually transmitted infection gonorrhea, caused by the Gram-negative bacterium Neisseria gonorrhoeae, can cause urethritis, cervicitis, and systemic disease, among other manifestations. N. gonorrhoeae has rapidly rising incidence along with increasing levels of antibiotic resistance to a broad range of drugs including first-line treatments. The rise in resistance has led to fears of untreatable gonorrhea causing substantial disease globally. In this review, we will describe multiple approaches being undertaken to slow and control this spread of resistance. First, a number of old drugs have been repurposed and new drugs are being developed with activity against Neisseria gonorrhoeae. Second, vaccine development, long an important goal, is advancing. Third, new diagnostics promise rapid detection of antibiotic resistance and a shift from empiric to tailored treatment. The deployment of these new tools for addressing the challenge of antibiotic resistance will require careful consideration to provide optimal care for all patients while extending the lifespan of treatment regimens.

Quantitative Analysis of Spectinomycin and Lincomycin in Poultry Eggs by Accelerated Solvent Extraction Coupled with Gas Chromatography Tandem Mass Spectrometry

A method based on accelerated solvent extraction (ASE) coupled with gas chromatography tandem mass spectrometry (GC-MS/MS) was developed for the quantitative analysis of spectinomycin and lincomycin in poultry egg (whole egg, albumen and yolk) samples. In this work, the samples were extracted and purified using an ASE350 instrument and solid-phase extraction (SPE) cartridges, and the parameters of the ASE method were experimentally optimized. The appropriate SPE cartridges were selected, and the conditions for the derivatization reaction were optimized. After derivatization, the poultry egg (whole egg, albumen and yolk) samples were analyzed by GC-MS/MS. This study used blank poultry egg (whole egg, albumen and yolk) samples to evaluate the specificity, sensitivity, linearity, recovery and precision of the method. The linearity (5.6-2000 μg/kg for spectinomycin and 5.9-200 μg/kg for lincomycin), correlation coefficient (≥0.9991), recovery (80.0%-95.7%), precision (relative standard deviations, 1.0%-3.4%), limit of detection (2.3-4.3 μg/kg) and limit of quantification (5.6-9.5 μg/kg) of the method met the requirements for EU parameter verification. Compared with traditional liquid-liquid extraction methods, the proposed method is fast and consumes less reagents, and 24 samples can be processed at a time. Finally, the feasibility of the method was evaluated by testing real samples, and spectinomycin and lincomycin residues in poultry eggs were successfully detected.

Multiresistant Neisseria gonorrhoeae: a new threat in second decade of the XXI century

Neisseria gonorrhoeae is an etiologic agent of gonorrhoea, one of the most common sexually transmitted diseases caused by bacteria. For many years, infections caused by N. gonorrhoeae were considered to be relatively easy to treat; however, resistance has emerged successively to all therapeutic agents used in treatment of the disease, e.g., penicillin, ciprofloxacin or azithromycin. Currently, the global problem is the emergence and a threat of spread of N. gonorrhoeae strains resistant to extended-spectrum cephalosporins (ESC), such as injectable ceftriaxone and oral-used cefixime. Especially, dangerous are multi-resistant strains resistant simultaneously to ESC and azithromycin. Three strains with high-level resistance to azithromycin and resistant to ESC were first time isolated in 2018. Moreover, in 2018, the first ESBL was described in N. gonorrhoeae and that makes the threat of appearing the ESBL mechanism of resistance in N. gonorrhoeae more real, even though the strain was sensitive to ceftriaxone. Molecular typing revealed that variants resistant to ESC occurred also among strains belonging to epidemic clonal complex CC1 (genogroup G1407) distinguished in NG-MAST typing system. The G1407 genogroup, in particular the ST1407 sequence type, is currently dominant in most European countries. The presence of different mechanisms of drug resistance significantly affects clinical practice and force changes in treatment regimens and introduction of new drugs.

Repurposing salicylamide for combating multidrug-resistant Neisseria gonorrhoeae

The U.S. Centers for Disease Control and Prevention (CDC) lists Neisseria gonorrhoeae as one of the most urgent antibiotic-resistant threats in the United States. This is due to the emergence of clinical isolates that have developed resistance to nearly every antibiotic used to treat gonorrhea and highlights the critical need to find new therapeutics. The present study discovered salicylamide, an analgesic and antipyretic drug, has antibacterial activity against 40 different antibiotic-resistant strains of N. gonorrhoeae (MIC 8-32 μg/ml) with low frequency of resistance <2.4x10^-9 Interestingly, salicylamide did not inhibit growth of bacterial species in the vaginal microflora involved in defense against gonococcal infections, such as Lactobacillus gasseri, L. jensenii, L. johnsonii, and L. crispatus A time-kill assay revealed that salicylamide is a rapidly bactericidal drug as it eradicated a high inoculum of N. gonorrhoeae within 10 hours. Salicylamide was superior to the drug of choice, ceftriaxone, in reducing the burden of intracellular N. gonorrhoeae by 97% in infected endocervical cells. Furthermore, salicylamide outperformed ceftriaxone in reducing expression of the pro-inflammatory cytokine IL-8 from endocervical cells infected with N. gonorrhoeae A checkerboard assay revealed that salicylamide exhibited a synergistic interaction with tetracycline and an additive relationship with azithromycin and ciprofloxacin, and ceftriaxone. A more in-depth investigation of the structure-activity-relationship of derivatives of salicylamide revealed the amide and hydroxyl groups are important for anti-gonorrheal activity. In conclusion, this study identified salicylamide as a promising candidate for further investigation as a novel treatment option for multidrug-resistant gonorrhea.

Aminomethyl spectinomycins: a novel antibacterial chemotype for biothreat pathogens

New antibiotics that are active against multi-drug-resistant strains and difficult-to-treat bacterial infections are needed. Synthetic modification of spectinomycin, a bacterial protein synthesis inhibitor, has been shown to increase antibacterial activity compared with spectinomycin. Aminomethyl spectinomycins are active against Gram-negative and Gram-positive bacterial pathogens. In this study, the ability of aminomethyl spectinomycins to treat biothreat pathogens is examined by MIC profiling, synergy testing, and in vivo efficacy experiments. Compound 1950 exhibited potent antibacterial activity against Gram-negative pathogens Brucella spp., Burkholderia mallei, and Francisella tularensis, but showed little to no growth inhibition against Burkholderia pseudomallei, Bacillus anthracis, and Yersinia pestis. Combination testing in checkerboard assays revealed that aminomethyl spectinomycin-antibiotic combinations had mainly an additive effect against the susceptible biodefense pathogens. The in vivo efficacy of compound 1950 was also demonstrated in mice infected with B. mallei (FMH) or F. tularensis (SchuS4). These results suggest that aminomethyl spectinomycins are promising new candidates for development of therapeutics against biodefense bacterial agents.

Pharmacokinetic Data Are Predictive of In Vivo Efficacy for Cefixime and Ceftriaxone against Susceptible and Resistant Neisseria gonorrhoeae Strains in the Gonorrhea Mouse Model

There is a pressing need for drug development for gonorrhea. Here we describe a pharmacokinetic (PK)/pharmacodynamic (PD) analysis of extended-spectrum cephalosporins (ESC) against drug-susceptible and drug-resistant gonococcal strains in a murine genital tract infection model. The PK determined in uninfected mice displayed a clear dose-response in plasma levels following single doses of ceftriaxone (CRO) (intraperitoneal) or cefixime (CFM) (oral). The observed doses required for efficacy against ESC-susceptible (ESC^s) strain FA1090 were 5 mg/kg of body weight (CRO) and 12 mg/kg (CFM); these doses had estimated therapeutic times (the time that the free drug concentration remains above the MIC [fT _MIC]) of 24 h and 37 h, respectively. No single dose of CRO or CFM was effective against ESC-resistant (ESC^r) strain H041. However, fractionation (three times a day every 8 h [TIDq8h]) of a 120-mg/kg dose of CRO resulted in estimated therapeutic times in the range of 23 h and cleared H041 infection in a majority (90%) of mice, comparable to the findings for gentamicin. In contrast, multiple CFM doses of 120 or 300 mg/kg administered TIDq8h cleared infection in ≤50% of mice, with the therapeutic times estimated from single-dose PK data being 13 and 27 h, respectively. This study reveals a clear relationship between plasma ESC levels and bacterial clearance rates in the gonorrhea mouse model. The PK/PD relationships observed in mice reflected those observed in humans, with in vivo efficacy against an ESC^s strain requiring doses that yielded an fT _MIC in excess of 20 to 24 h. PK data also accurately predicted the failure of single doses of ESCs against an ESC^r strain and were useful in designing effective dosing regimens.

Female Mouse Model of Neisseria gonorrhoeae Infection

Mouse models of infection are important tools in the study of infectious disease or host the development of products to prevent or treat infections. The estradiol-treated mouse model of Neisseria gonorrhoeae genital tract infection has proved to be a valuable system for determining the importance of gonococcal factors that mediate evasion of host innate effectors in vivo or host gonococcal adaptation to hormonally driven host factors in females. Examination of mechanisms that Neisseria gonorrhoeae uses to subvert the host immune response also has been greatly aided by this whole model system, as have studies on the consequence of antibiotic resistance mutations on gonococcal fitness in vivo and the search for new antibiotics to treat antibiotic-resistant infections. The strict human specificity of N. gonorrhoeae limits the ability of experimental murine infection to mimic human infection. However, in recent years, the development of transgenic mice and protocols for supplementing mice with human factors has improved animal modeling of gonorrhea. To date, however, because the mouse estrous cycle is much shorter than the human reproductive cycle, all reported gonorrhea mouse models require treatment with estradiol and antibiotics to maintain an estrus-like state and suppress the overgrowth of inhibitory commensal flora that occurs under the influence of estrogen to allow sustained N. gonorrhoeae infection. In this chapter, we detail the methods used to (1) prepare the mice for experimental infection with N. gonorrhoeae, (2) inoculate mice and quantitatively culture vaginal swabs for noncompetitive and competitive infection experiments, and (3) monitor the host innate immune response to infection.

Selective Inhibition of Neisseria gonorrhoeae by a Dithiazoline in Mixed Infections with Lactobacillus gasseri

The Gram-negative human pathogen Neisseria gonorrhoeae has progressively developed resistance to antibiotic monotherapies, and recent failures of dual-drug therapy have heightened concerns that strains resistant to all available antibiotics will begin circulating globally. Targeting bacterial cell wall assembly has historically been effective at treating infections with N. gonorrhoeae, but as the effectiveness of β-lactams (including cephalosporins) is challenged by increasing resistance, research has expanded into compounds that target the numerous other enzymes with roles in peptidoglycan metabolism. One example is the dithiazoline compound JNJ-853346 (DTZ), which inhibits the activity of an Escherichia coli serine protease l,d-carboxypeptidase (LdcA). Recently, the characterization of an LdcA homolog in N. gonorrhoeae revealed localization and activity differences from the characterized E. coli LdcA, prompting us to explore the effectiveness of DTZ against N. gonorrhoeae We found that DTZ is effective at inhibiting N. gonorrhoeae in all growth phases, unlike the specific stationary-phase inhibition seen in E. coli Surprisingly, DTZ does not inhibit gonococcal LdcA enzyme activity, and DTZ sensitivity is not significantly decreased in ldcA mutants. While effective against numerous N. gonorrhoeae strains, including recent multidrug-resistant isolates, DTZ is much less effective at inhibiting growth of the commensal species Lactobacillus gasseri DTZ treatment during coinfections of epithelial cells resulted in significant lowering of gonococcal burden and interleukin-8 secretion without significantly impacting recovery of viable L. gasseri This selective toxicity presents a possible pathway for the use of DTZ as an effective antigonococcal agent at concentrations that do not impact vaginal commensals.

Future Prospects for Neisseria gonorrhoeae Treatment

Gonorrhea is a sexually transmitted disease with a high morbidity burden. Incidence of this disease is rising due to the increasing number of antibiotic-resistant strains. Neisseria gonorrhoeae has shown an extraordinary ability to develop resistance to all antimicrobials introduced for its treatment. In fact, it was recently classified as a &ldquo;Priority 2&rdquo; microorganism in the World Health Organization (WHO) Global Priority List of Antibiotic-Resistant Bacteria to Guide Research, Discovery and Development of New Antibiotics. Seeing as there is no gonococcal vaccine, control of the disease relies entirely on prevention, diagnosis, and, especially, antibiotic treatment. Different health organizations worldwide have established treatment guidelines against gonorrhea, mostly consisting of dual therapy with a single oral or intramuscular dose. However, gonococci continue to develop resistances to all antibiotics introduced for treatment. In fact, the first strain of super-resistant N.gonorrhoeae was recently detected in the United Kingdom, which was resistant to ceftriaxone and azithromycin. The increase in the detection of resistant gonococci may lead to a situation where gonorrhea becomes untreatable. Seeing as drug resistance appears to be unstoppable, new treatment options are necessary in order to control the disease. Three approaches are currently being followed for the development of new therapies against drug-resistant gonococci: (1) novel combinations of already existing antibiotics; (2) development of new antibiotics; and (3) development of alternative therapies which might slow down the appearance of resistances. N. gonorrhoeae is a public health threat due to the increasing number of antibiotic-resistant strains. Current treatment guidelines are already being challenged by this superbug. This has led the scientific community to develop new antibiotics and alternative therapies in order to control this disease.