The JAID/JSC guidelines to Clinical Management of Infectious Disease 2017 concerning male urethritis and related disorders

The novel 2024 WHO Neisseria gonorrhoeae reference strains for global quality assurance of laboratory investigations and superseded WHO N. gonorrhoeae reference strains-phenotypic, genetic and reference genome characterization

OBJECTIVES

MDR and XDR Neisseria gonorrhoeae strains remain major public health concerns internationally, and quality-assured global gonococcal antimicrobial resistance (AMR) surveillance is imperative. The WHO global Gonococcal Antimicrobial Surveillance Programme (GASP) and WHO Enhanced GASP (EGASP), including metadata and WGS, are expanding internationally. We present the phenotypic, genetic and reference genome characteristics of the 2024 WHO gonococcal reference strains (n = 15) for quality assurance worldwide. All superseded WHO gonococcal reference strains (n = 14) were identically characterized.

MATERIAL AND METHODS

The 2024 WHO reference strains include 11 of the 2016 WHO reference strains, which were further characterized, and four novel strains. The superseded WHO reference strains include 11 WHO reference strains previously unpublished. All strains were characterized phenotypically and genomically (single-molecule PacBio or Oxford Nanopore and Illumina sequencing).

RESULTS

The 2024 WHO reference strains represent all available susceptible and resistant phenotypes and genotypes for antimicrobials currently and previously used (n = 22), or considered for future use (n = 3) in gonorrhoea treatment. The novel WHO strains include internationally spreading ceftriaxone resistance, ceftriaxone resistance due to new penA mutations, ceftriaxone plus high-level azithromycin resistance and azithromycin resistance due to mosaic MtrRCDE efflux pump. AMR, serogroup, prolyliminopeptidase, genetic AMR determinants, plasmid types, molecular epidemiological types and reference genome characteristics are presented for all strains.

CONCLUSIONS

The 2024 WHO gonococcal reference strains are recommended for internal and external quality assurance in laboratory examinations, especially in the WHO GASP, EGASP and other GASPs, but also in phenotypic and molecular diagnostics, AMR prediction, pharmacodynamics, epidemiology, research and as complete reference genomes in WGS analysis.

Antimicrobial treatment and resistance in sexually transmitted bacterial infections

Sexually transmitted infections (STIs) have been part of human life since ancient times, and their symptoms affect quality of life, and sequelae are common. Socioeconomic and behavioural trends affect the prevalence of STIs, but the discovery of antimicrobials gave hope for treatment, control of the spread of infection and lower rates of sequelae. This has to some extent been achieved, but increasing antimicrobial resistance and increasing transmission in high-risk sexual networks threaten this progress. For Neisseria gonorrhoeae, the only remaining first-line treatment (with ceftriaxone) is at risk of becoming ineffective, and for Mycoplasma genitalium, for which fewer alternative antimicrobial classes are available, incurable infections have already been reported. For Chlamydia trachomatis, in vitro resistance to first-line tetracyclines and macrolides has never been confirmed despite decades of treatment of this highly prevalent STI. Similarly, Treponema pallidum, the cause of syphilis, has remained susceptible to first-line penicillin.

Emergence of Neisseria gonorrhoeae Clone with Reduced Susceptibility to Sitafloxacin in China: An In Vitro and Genomic Study

Drug-resistant Neisseria gonorrhoeae poses an urgent threat to public health. Recently, sitafloxacin, a new-generation fluoroquinolone, has shown high in vitro activity against drug-resistant N. gonorrhoeae. However, data on its effectiveness in clinical isolates remains limited. In this study, we collected 507 N. gonorrhoeae isolates from 21 hospitals in Shanghai, China, during 2020 and 2021. Antimicrobial susceptibility testing revealed that sitafloxacin minimum inhibitory concentrations (MICs) exhibited a bimodal distribution, ranging from <0.004 to 2 mg/L. The MIC50 and MIC90 for sitafloxacin were 0.125 mg/L and 0.5 mg/L, respectively, which are 32 and 16 times lower than those for ciprofloxacin (4 mg/L and 8 mg/L, respectively). Sitafloxacin demonstrated high in vitro activity against isolates resistant to either ceftriaxone, azithromycin, or both. Notably, among the isolates with reduced sitafloxacin susceptibility (MIC ≥ MIC90), 83.7% (36/43) were identified as sequence type (ST) 8123. Further phylogenetic analysis showed that ST8123 has evolved into two subclades, designated as subclade-I and subclade-II. A majority of the isolates (80%, 36/45) within subclade-I exhibited reduced susceptibility to sitafloxacin. In contrast, all isolates from subclade-II were found to be susceptible to sitafloxacin. Subsequent genomic investigations revealed that the GyrA-S91F, D95Y, and ParC-S87N mutations, which were exclusively found in ST8123 subclade-I, might be linked to reduced sitafloxacin susceptibility. Our study reveals that sitafloxacin is a promising antibiotic for combating drug-resistant N. gonorrhoeae. However, caution is advised in the clinical application of sitafloxacin for treating N. gonorrhoeae infections due to the emergence of a clone exhibiting reduced susceptibility.

Current and emerging strategies to curb antibiotic-resistant urinary tract infections

Rising rates of antibiotic resistance in uropathogenic bacteria compromise patient outcomes and prolong hospital stays. Consequently, new strategies are needed to prevent and control the spread of antibiotic resistance in uropathogenic bacteria. Over the past two decades, sizeable clinical efforts and research advances have changed urinary tract infection (UTI) treatment and prevention strategies to conserve antibiotic use. The emergence of antimicrobial stewardship, policies from national societies, and the development of new antimicrobials have shaped modern UTI practices. Future UTI management practices could be driven by the evolution of antimicrobial stewardship, improved and readily available diagnostics, and an improved understanding of how the microbiome affects UTI. Forthcoming UTI treatment and prevention strategies could employ novel bactericidal compounds, combinations of new and classic antimicrobials that enhance bacterial killing, medications that prevent bacterial attachment to uroepithelial cells, repurposing drugs, and vaccines to curtail the rising rates of antibiotic resistance in uropathogenic bacteria and improve outcomes in people with UTI.

Affinity of β-Lactam Antibiotics for Neisseria gonorrhoeae Penicillin-Binding Protein 2 Having Wild, Cefixime-Reduced-Susceptible, and Cephalosporin (Ceftriaxone)-Resistant penA Alleles

Multidrug-resistant Neisseria gonorrhoeae is a serious concern worldwide. Resistance to β-lactam antibiotics occurs through mutations in penicillin-binding proteins (PBPs), acquisition of β-lactamases, and alteration of antibiotic penetration. Mosaic structures of penA, which encodes PBP2, play a major role in resistance to β-lactams, especially cephalosporins. Ceftriaxone (CRO) is recognized as the only satisfiable antibiotic for the treatment of gonococcal infections; however, CRO-resistant isolates have emerged in the community. Here, we examined the affinity of β-lactam antibiotics for recombinant PBP2 in a competition assay using fluorescence-labeled penicillin. We found no or little difference in the affinities of penicillins and meropenem (MEM) for PBP2 from cefixime (CFM)-reduced-susceptible strain and cephalosporin-resistant strain. However, the affinity of cephalosporins, including CRO, for PBP2 from the cephalosporin-resistant strain was markedly lower than that for PBP2 from the CFM-reduced-susceptible-resistant strain. Notably, piperacillin (PIP) showed almost the same affinity for PBP2 from penicillin-susceptible, CFM-reduced-susceptible, and cephalosporin (including CRO)-resistant strains. Thus, PIP/tazobactam and MEM are candidate antibiotics for the treatment of CRO-resistant/multidrug-resistant N. gonorrhoeae.

Neisseria gonorrhoeae antimicrobial susceptibility trends in Bangkok, Thailand, 2015-21: Enhanced Gonococcal Antimicrobial Surveillance Programme (EGASP)

Objectives

Rising antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a global public health concern. Many ceftriaxone-resistant cases have been linked to Asia. In the WHO/CDC global Enhanced Gonococcal Antimicrobial Surveillance Programme (EGASP), we conducted AMR surveillance at two clinical sites in Bangkok, Thailand, 2015-21.

Methods

Urethral discharge samples, from males with urethral discharge and/or dysuria, were Gram-stained and cultured. ETEST was performed to determine AMR. EGASP MIC alert values, CLSI and EUCAST breakpoints were used.

Results

In 2015-21, gonococcal isolates were cultured from 1928 cases; most (64.1%) were males reporting having sex with females. The sensitivity and specificity of Gram-stained microscopy compared with culture for detection of gonococci were 97.5% and 96.6%, respectively. From 2015 to 2021, the azithromycin MIC90 increased from 0.125 to 1 mg/L, and the MIC90 of ceftriaxone and cefixime increased from 0.008 and ≤0.016 mg/L to 0.032 and 0.064 mg/L, respectively. Eight EGASP MIC alert values (in seven isolates) were identified. Five alert values were for cefixime (all resistant according to EUCAST breakpoints) and three for azithromycin (all resistant according to EUCAST breakpoints). The average annual resistance to ciprofloxacin during 2015-21 was 92%.

Conclusions

A continuous high susceptibility to ceftriaxone, Thailand's first-line gonorrhoea treatment, was found. However, the increasing MICs of ceftriaxone, cefixime and azithromycin are a substantial threat, especially considering these are the last remaining options for the treatment of gonorrhoea. To monitor AMR, continuous and quality-assured gonococcal AMR surveillance such as the Thai WHO/CDC EGASP, ideally including WGS, is imperative globally.

The third nationwide surveillance of antimicrobial susceptibility against Neisseria gonorrhoeae from male urethritis in Japan, 2016-2017

Neisseria gonorrhoeae is one of the important pathogens of sexually transmitted infections. N. gonorrhoeae is rapidly becoming antimicrobial resistant, and there are few drugs that are effective in the initial treatment of gonorrhea. To understand the trends of antimicrobial susceptibility of N. gonorrhoeae, the Surveillance Committee of the Japanese Society of Infectious Diseases, the Japanese Society for Chemotherapy, and the Japanese Society of Clinical Microbiology conducted the third nationwide antimicrobial susceptibility surveillance of N. gonorrhoeae isolated from male urethritis. The specimens were collected from male patients with urethritis at 30 facilities from May 2016 to July 2017. From the 159 specimens collected, 87 N. gonorrhoeae strains were isolated, and 85 were tested for susceptibility to 21 antimicrobial agents. All strains were non-susceptible to penicillin G. Seven strains (8.2%) were β-lactamase-producing strains. The rates of susceptibility to cefixime and cefpodoxime were 96.5% and 52.9%, respectively. Three strains were non-susceptible with a minimum inhibitory concentration (MIC) of 0.5 mg/L for cefixime. None of the strains were resistant to ceftriaxone or spectinomycin. The susceptibility rate for ciprofloxacin was 23.5% (20 strains), and no strains showed intermediate susceptibility. The susceptibility rate against azithromycin was 81.2%, with one strain isolated with a MIC of 8 mg/L against azithromycin. The results of this surveillance indicate that ceftriaxone and spectinomycin, which are currently recommended for gonococcal infections in Japan, appear to be effective. It will be necessary to further expand the scale of the next surveillance to understand the current status of drug-resistant N. gonorrhoeae in Japan.

Genomic surveillance and antimicrobial resistance in Neisseria gonorrhoeae isolates in Bangkok, Thailand in 2018

OBJECTIVES

Antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a substantial global public health problem. Gonococcal infections acquired in or from Asia represent most verified ceftriaxone treatment failures, and several ceftriaxone-resistant strains have emerged in Asia and subsequently spread globally. Additionally, in Thailand the gonorrhoea incidence remains high. Herein, we investigate the genomic diversity, AMR and AMR determinants in gonococcal isolates cultured in 2018 in Bangkok, Thailand.

METHODS

Gonococcal isolates from males (n = 37) and females (n = 62) were examined by Etest and WGS. AMR determinants and molecular epidemiological STs were characterized. For phylogenomic comparison, raw sequence data were included from China (432 isolates), Japan (n = 270), Vietnam (n = 229), Thailand (n = 3), a global dataset (n = 12 440) and the 2016 WHO reference strains plus WHO Q (n = 15).

RESULTS

In total, 88, 66 and 41 different NG-MAST, NG-STAR and MLST STs, respectively, and 31 different NG-STAR clonal complexes were found. A remarkably high frequency (88%) of β-lactamase TEM genes was detected and two novel TEM alleles were found. The phylogenomic analysis divided the isolates into the previously described lineages A and B, with a large proportion of Thai isolates belonging to the novel sublineage A3.

CONCLUSIONS

We describe the first molecular epidemiological study using WGS on gonococcal isolates from Thailand. The high prevalence of AMR and AMR determinants for ciprofloxacin, tetracycline and benzylpenicillin, and some strains belonging to clones/clades especially in sublineage A2 that are prone to develop resistance to extended-spectrum cephalosporins (ESCs) and azithromycin, should prompt continued and strengthened AMR surveillance, including WGS, of N. gonorrhoeae in Thailand.

Randomized controlled trial of the relative efficacy of high-dose intravenous ceftriaxone and oral cefixime combined with doxycycline for the treatment of Chlamydia trachomatis and Neisseria gonorrhoeae co-infection

OBJECTIVES

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are the commonest bacterial causes of sexually transmitted infections in humans with high incidence of co-infection. Treatment with high doses of ceftriaxone (CRO) and cefixime (CFM) is strongly recommended due to the reduced drug susceptibility of NG. However, their safety and efficacy have not been confirmed. We compared the safety and efficacy of a single 1 g intravenous (IV) dose of ceftriaxone (CRO) plus doxycycline (DOX) versus a single 800 mg oral dose of cefixime (CFM) plus DOX for the treatment of NG-CT co-infection.

METHODS

An open-label randomized controlled trial was conducted on 125 individuals aged > 18 years with untreated gonorrhea and chlamydia to compare a single 1 g intravenous dose of CRO + DOX and a single 800 mg oral dose of CFM + DOX. The primary outcome was the clearance of NG from all the initially infected sites. Secondary outcomes included symptom resolution, changes in the serum clearance levels, glomerular filtration rate, and antibiotic minimum inhibitory concentrations.

RESULTS

Both regimens were highly effective in treating gonorrhea with success rates of 96.7% (95% confidence interval [CI] 88.8-99.1%) for CRO and 95.3% (95% CI 87.1-98.4%) for CFM. However, CRO + DOX was superior to CFM + DOX for the treatment of NG-CT co-infection (odds ratio 4.41, 95% CI 1.11-25.7). The safety profiles of the two regimens were similar.

CONCLUSIONS

CRO + DOX was superior to CFM + DOX for the treatment of NG-CT co-infection. CFM + DOX may be indicated in patients with CRO allergy and in settings where CRO is unavailable. Trial registration ClinicalTrials.gov (NCT05216744) on 31/01/22.

National surveillance of Neisseria gonorrhoeae antimicrobial susceptibility and epidemiological data of gonorrhoea patients across Brazil, 2018–20

Objectives

To (i) describe the nationwide antimicrobial susceptibility of Neisseria gonorrhoeae (NG) isolates cultured across Brazil in 2018–20 and compare it with NG antimicrobial resistance data from 2015–16, and (ii) present epidemiological data of the corresponding gonorrhoea patients in 2018–20.

Methods

Twelve representative sentinel sites cultured NG isolates from men with urethral discharge. Susceptibility to eight antimicrobials was examined using agar dilution method, according to WHO standards. The consenting participants were invited to provide epidemiological data.

Results

In total, 633 NG isolates (one isolate per participant) were analysed, and 449 (70.9%) questionnaires were answered. Heterosexual (68.2%) and homosexual (23.1%) sexual orientations were common, and most prevalent types of unprotected sexual intercourse were vaginal insertive (69.9%), oral giving (56.6%) and anal insertive (47.4%). The levels of in vitro NG resistance to ciprofloxacin, tetracycline, benzylpenicillin, azithromycin, cefixime, gentamicin, spectinomycin and ceftriaxone were 67.3%, 40.0%, 25.7%, 10.6%, 0.3%, 0%, 0% and 0%, respectively. Compliance with the recommended first-line ceftriaxone 500 mg plus azithromycin 1 g therapy was high (90.9%).

Conclusions

Compared with 2015–16, ciprofloxacin resistance has remained high and azithromycin and cefixime resistance rates have increased in Brazil. Resistance remained lacking to ceftriaxone, gentamicin and spectinomycin, which all are gonorrhoea treatment options. The increasing azithromycin resistance in Brazil and internationally may threaten the future use of azithromycin in dual regimens for treatment of gonorrhoea. Consequently, continued and enhanced quality-assured surveillance of gonococcal AMR, and ideally also treatment failures and including WGS, is imperative in Brazil and worldwide.

A Single Amino Acid Substitution in Elongation Factor G Can Confer Low-Level Gentamicin Resistance in Neisseria gonorrhoeae

The continued emergence of Neisseria gonorrhoeae isolates which are resistant to first-line antibiotics has reinvigorated interest in alternative therapies such as expanded use of gentamicin (Gen). We hypothesized that expanded use of Gen promotes emergence of gonococci with clinical resistance to this aminoglycoside. To understand how decreased susceptibility of gonococci to Gen might develop, we selected spontaneous low-level Gen-resistant (Gen^R) mutants (Gen MIC = 32 μg/mL) of the Gen-susceptible strain FA19. Consequently, we identified a novel missense mutation in fusA, which encodes elongation factor G (EF-G), causing an alanine (A) to valine (V) substitution at amino acid position 563 in domain IV of EF-G; the mutant allele was termed fusA2. Transformation analysis showed that fusA2 could increase the Gen MIC by 4-fold. While possession of fusA2 did not impair either in vitro gonococcal growth or protein synthesis, it did result in a fitness defect during experimental infection of the lower genital tract in female mice. Through bioinformatic analysis of whole-genome sequences of 10,634 international gonococcal clinical isolates, other fusA alleles were frequently detected, but genetic studies revealed that they could not decrease Gen susceptibility in a similar manner to fusA2. In contrast to these diverse international fusA alleles, the fusA2-encoded A563V substitution was detected in only a single gonococcal clinical isolate. We hypothesize that the rare occurrence of fusA2 in N. gonorrhoeae clinical isolates is likely due to a fitness cost during infection, but compensatory mutations which alleviate this fitness cost could emerge and promote Gen^R in global strains.