High prevalence of ciprofloxacin-resistant Neisseria gonorrhoeae in Northern Taiwan

Emergence of a predominant sequence type ST7363 and the increasing trend of resistance to cefixime and ceftriaxone in Neisseria gonorrhoeae in Southern Taiwan, 2019-2021

BACKGROUND/PURPOSE

Multi-drug resistance and the presence of epidemic lineages of Neisseria gonorrhoeae locally and globally were important clinical and public health issues. We aimed to investigate the molecular epidemiology and the antimicrobial susceptibility profiles of N. gonorrhoeae in Southern Taiwan.

METHODS

Between 2019 and 2021, adult patients who had suspected gonorrhea and attended a urology clinic in southern Taiwan were recruited to participate in this study. Clinical data from medical records and a questionnaire, antimicrobial susceptibility testing using a disk diffusion test in accordance with the guidelines by the Clinical and Laboratory Standards Institute, and Multi-locus sequence typing (MLST) were analyzed.

RESULTS

A total of 500 patients participated in the surveillance study. Among them, 232 N. gonorrhoeae isolates were identified, but only 164 isolates were recovered for further research. ST7363 (n = 83, 50.61%) was found to be the predominant sequence type, followed by ST1583 (n = 24, 14.63%), ST1588 (n = 13, 7.93%), and ST7827 (n = 12, 7.32%). 100% resistance to penicillin and 99.4% non-susceptible rate of ciprofloxacin were observed. The azithromycin resistant rate being 15.24% and the cefixime non-susceptible rate being 17.07% were alarming, both with decreasing trends in susceptibilities during 2019-2021. The 25 azithromycin resistant isolates were mainly belonged to ST7363 (n = 12) and ST7827 (n = 3). Seven (4.2%) isolates were ceftriaxone non-susceptible. Among them, four were assigned to be ST 7827 and three belonged to ST7363.

CONCLUSION

We observed the emergence of a predominant sequence type ST7363 in southern Taiwan. Compared with previous Taiwan studies, the increasing trend of resistance to cefixime and ceftriaxone necessitates clinicians' alertness for clinical treatment response of the extended spectrum cephalosporins and the further surveillance monitor.

Antibiotic Susceptibility Monitoring of Neisseria gonorrhoeae in Bacolod City, Philippines

A local study was conducted to monitor the antibiotic susceptibility of N. gonorrhoeae in Bacolod City, Philippines. A total of 88 isolates were taken during the period of 1 January 2015 to 30 June 2017, from male patients ages 12 to 72 years. The highest incidence of gonorrhea infection was in the group aged 20⁻24 years (34.09%). The susceptibility pattern to antibiotics was as follows: ceftriaxone 100%, cefixime 82.6%, spectinomycin 92.1%, ciprofloxacin 4.9%, tetracycline 5.1%, and penicillin G with 0%. All isolates were noted to produce beta-lactamase, which can be attributed to plasmid-mediated penicillin resistance. These findings indicate that the resistance rates of N. gonorrhoeae to most commonly-used antibiotics are increasing, and that ceftriaxone remains an effective antibiotic in treating gonorrhea infections locally.

Changes in the six most common sequence types of Neisseria gonorrhoeae, including ST4378, identified by surveillance of antimicrobial resistance in northern Taiwan from 2006 to 2013

BACKGROUND

There has been no longitudinal study of drug susceptibility in Neisseria gonorrhoeae in Taiwan since 2006.

METHODS

We collected 1090 gonococcal isolates from Taipei City Hospital, Taiwan from April 2006 to August 2013. We used a disk diffusion assay to determine the susceptibility to five antibiotics and an E-test to determine the minimum inhibitory concentrations for cefixime and ceftriaxone in isolates with resistance. Neisseria gonorrhoeae-multi Antigen Sequence Typing and DNA sequencing of the por and tbpB genes were used to identify sequence types.

RESULTS

Among the 1090 isolates, the resistances to penicillin, ciprofloxacin, cefpodoxime, cefixime, and ceftriaxone were 61.01%, 83.39%, 9.63%, 6.70%, and 2.39%, respectively. The highest minimum inhibitory concentrations of cefixime and ceftriaxone were 0.19 mg/L and 0.50 mg/L, respectively. There were 327 sequence types. The four most common sequence types in homosexuals were ST4378, ST359, ST4654, and ST547; the two most common sequence types in heterosexuals were ST421 and ST419. Each of these sequence types had more than 25 isolates. There were significant differences in the sequence types in patients with different sexual orientations (p < 0.001).

CONCLUSION

Oral cefixime or ceftriaxone injections were used as first-line drugs for the treatment of gonorrhea from 2006 to 2013 because gonorrhea isolates had low minimum inhibitory concentrations for these two drugs. The abrupt emergence of ST4378 (closely related to the notorious ST1407) since 2009 is a cause for alarm. Changes in sexual behavior, including an increase in sexual activity without the use of condoms, may have contributed to the peak in gonorrhea in 2010. Further molecular epidemiological investigations are required.

Decreased susceptibility of Neisseria gonorrhoeae isolates from Switzerland to Cefixime and Ceftriaxone: antimicrobial susceptibility data from 1990 and 2000 to 2012

Background

Neisseria gonorrhoeae can rapidly develop resistance to antimicrobial agents. Over the last years, decreased gonococcal susceptibility to third-generation cephalosporins, especially cefixime, emerged worldwide. Therefore, current international guidelines recommend dual therapy for gonorrhoea with ceftriaxone plus either azithromycin or doxycycline. Gonococcal susceptibility data in Switzerland are sparse.

Methods

We investigated the prevalence of antibiotic susceptibility of N. gonorrhoeae in specimens collected between 1990 and 2012 at the University of Zurich, Switzerland. Minimum inhibitory concentrations (MICs) for cefixime, ceftriaxone, ciprofloxacin, and penicillin were determined by Etests. The European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints were used to define reduced susceptibility.

Results

A total of 320 isolates were tested. Between 1990 and 2006 all tested samples were susceptible to both cephalosporins. Subsequently, the prevalence of elevated MICs for cefixime increased to 10.4% (2007/2008), 11.5% (2009/2010), and 11.4% (2011/2012); and for ceftriaxone to 2.4% (2007/2008), 4.7% (2009/2010), and 0% (2011/2012), respectively. The prevalence of resistance to ciprofloxacin (72.7%) and penicillin (22.7%) was high in 2011/2012.

Conclusions

Decreasing susceptibility of N. gonorrhoeae to third-generation cephalosporins in Switzerland supports treatment recommendations with ceftriaxone plus azithromycin or doxycycline. Health-care providers need to be aware of possible treatment failures with cephalosporins. Continued surveillance of gonococcal antimicrobial resistance is essential.

On the pathway to better birth outcomes? A systematic review of azithromycin and curable sexually transmitted infections

The WHO recommends the administration of sulfadoxine-pyrimethamine (SP) to all pregnant women living in areas of moderate (stable) to high malaria transmission during scheduled antenatal visits, beginning in the second trimester and continuing to delivery. Malaria parasites have lost sensitivity to SP in many endemic areas, prompting the investigation of alternatives that include azithromycin-based combination (ABC) therapies. Use of ABC therapies may also confer protection against curable sexually transmitted infections and reproductive tract infections (STIs/RTIs). The magnitude of protection at the population level would depend on the efficacy of the azithromycin-based regimen used and the underlying prevalence of curable STIs/RTIs among pregnant women who receive preventive treatment. This systematic review summarizes the efficacy data of azithromycin against curable STIs/RTIs.

Characteristics and dissemination of mosaic penicillin-binding protein 2-harboring multidrug-resistant Neisseria gonorrhoeae isolates with reduced cephalosporin susceptibility in northern Taiwan

Among 254 Neisseria gonorrhoeae isolates from a sexually transmitted infection (STI) clinic in northern Taiwan, 69 isolates were found to contain the mosaic penA (MA) gene and were associated with elevated cefixime and ceftriaxone MICs. Most of these MA gene-harboring isolates were also resistant to penicillin (71.4%) and ciprofloxacin (100%) and were from men who have sex with men (MSM) or from bisexual men (81.2%). Three major sequence types (ST835, ST2180, and ST2253) constituted 55.7% of these isolates. The major sequence types harboring the mosaic penA gene may represent major sexual networks responsible for the emergence/introduction and the spread of the multidrug-resistant clones in Taiwan.

Antimicrobial susceptibility of Neisseria gonorrhoeae isolates determined by the agar dilution, disk diffusion and Etest methods: comparison of results using GC agar and chocolate agar

Although the use of GC agar for determining Neisseria gonorrhoeae antimicrobial susceptibilities is suggested by Clinical and Laboratory Standard Institute (CLSI) guidelines, chocolate agar is still used in some regions owing to its low cost and availability. To determine the differences in susceptibilities determined using GC and chocolate agars, 163 non-duplicate N. gonorrhoeae isolates were tested. Minimum inhibitory concentrations (MICs) and percent susceptibilities determined using the GC agar dilution method, respectively, were as follows: ceftriaxone, 0.004-0.125 mg/L, 100%; cefixime, 0.002 mg/L to >32 mg/L, 98.2%; and ciprofloxacin, 0.002 mg/L to >32 mg/L, 3.1%. Comparison of ceftriaxone MICs determined by the Etest using GC agar and chocolate agar showed that use of GC agar tended to result in lower MICs than GC agar dilution, whilst use of chocolate agar tended to result in higher MICs (concordance, 55.8% and 82.8%, respectively). Disk inhibition zones obtained using GC agar and chocolate agar (and their correlation coefficients) were, respectively: ceftriaxone, 35-55 mm and 25-50mm (0.46); ciprofloxacin, 6-55 mm and 6-43 mm (0.84); and penicillin, 6-47 mm and 6-50 mm (0.93). Use of chocolate agar with the disk diffusion method for ceftriaxone was associated with a 5.5% false resistance rate. In summary, compared with GC agar, susceptibility testing using chocolate agar tends to yield higher MICs with the Etest and smaller disk inhibition zones with disk diffusion methods. Clinical microbiology laboratories should strictly adhere to CLSI recommendations by using GC agar instead of chocolate agar when performing susceptibility testing for N. gonorrhoeae.

Population dynamics of Neisseria gonorrhoeae in Shanghai, China: a comparative study

Background

Gonorrhea is a major sexually transmitted disease (STD) in many countries worldwide. The emergence of fluoroquinolone resistance has complicated efforts to control and treat this disease. We report the first study of the evolutionary processes acting on transmission dynamics of a resistant gonococcal population from Shanghai, China. We compare these findings with our previous study of the evolution of a fluoroquinolone sensitive gonococcal population from Baltimore, MD.

Methods

Ninety six gonococcal samples were collected from male patients in Shanghai, China. All samples were fluoroquinolone resistant. Seven MLST housekeeping genes, two fluoroquinolone resistance genes (gyrA and parC) and the porB gene were sequenced and subjected to population genetic and evolutionary analyses. We estimated genetic diversity, recombination, growth, and selective pressure. The evolutionary history and population dynamics of the Shanghai population were also inferred and compared with that observed in a fluoroquinolone sensitive gonococcal population from Baltimore.

Results

For both populations, mutation plays a larger role than recombination in the evolution of the porB gene, whereas the latter seems to be the main force driving the evolution of housekeeping and fluoroquinolone resistance genes. In both populations there was evidence for positively selected sites in all genes analyzed. The phylogenetic analyses showed no temporal clustering in the Shanghai gonococcal population, nor did we detect shared allelic profiles between the Shanghai and the Baltimore populations. Past population dynamics of gonococcal strains from Shanghai showed a rising relative effective population size (Ne) in MLST genes with a declining relative Ne for gyrA and parC, whereas among sensitive strains from Baltimore we previously observed concordance among these genes. In both Shanghai and Baltimore, the past population dynamics of gonococcal strains tracked changes in the prevalence of gonorrhea.

Conclusions

Our study illustrates both similarities and differences in the evolutionary processes acting on gonococcal populations in different geographic areas. An explanation of this pattern that may apply in China is the continued use of quinolone antibiotics despite widespread resistance. Population genetic analysis of gonococcal strains in conjunction with epidemiological surveillance may provide insights into the epidemic behavior of antibiotic resistant strains and help to design control measures.

Suboptimal therapy and clinical management of gonorrhoea in an area with high-level antimicrobial resistance

The choice of antimicrobial agents for the treatment of gonorrhoea is critical in areas where the prevalence of drug resistance is high. This study aimed to evaluate the antibiotic treatment of gonorrhoea in endemic areas. During 1999-2004, all Neisseria gonorrhoeae infections (n = 90) were evaluated. Patients' medical records and antibiotic treatment regimens were retrospectively reviewed if their isolates were viable (n = 65). In vitro antimicrobial susceptibility of N. gonorrhoeae isolates was performed. Urethritis (89%) and pelvic inflammatory disease (42%) were the most common presentations among men (n = 53) and women (n = 12), respectively. Of 54 patients with uncomplicated N. gonorrhoeae infection, 32 of them received appropriate antibiotics, including cefuroxime (n = 20), ceftriaxone (n = 10), ciprofloxacin (n = 1) and azithromycin (n = 1) during follow-ups. Among 65 patients, 53.8% were notified to the health authority. Check-ups of other sexually transmitted diseases were carried out in only 46% of patients. Not all isolates were susceptible to penicillin, 96.9% were resistant to tetracycline and 86% were resistant to ciprofloxacin. Ceftriaxone, cefixime, spectinomycin and azithromycin were active in vitro against all isolates. In conclusion, It is crucial to develop treatment guidelines according to regional antimicrobial resistances and educational programmes to improve clinical care for genital gonococcal diseases.

Molecular epidemiological identification of Neisseria gonorrhoeae clonal clusters with distinct susceptibility profiles associated with specific groups at high risk of contracting human immunodeficiency virus and syphilis

From April 2006 to August 2007, a total of 146 Neisseria gonorrhoeae isolates collected from 139 male patients in Taipei, Taiwan, were analyzed by N. gonorrhoeae multiantigen sequence typing (NG-MAST) and antibiotic susceptibility testing. The resistance rates of all isolates to ciprofloxacin, cefpodoxime, and cefixime were 76.7 (112/146), 21.2 (31/146), and 16.4% (24/146), respectively. NG-MAST identified 71 sequence types (STs), of which 21 STs contained 2 to 21 isolates. The isolates that belonged to the three major ST clusters typically were from patients who had specific epidemiological characteristics (such as sexual orientation and human immunodeficiency virus status). The major ST clones exhibited distinct resistance profiles and are associated with specific groups at high risk of human immunodeficiency virus and syphilis infections.

Surveillance of antimicrobial susceptibilities in Neisseria gonorrhoeae in Nanjing, China, 1999-2006

OBJECTIVE

To monitor the frequency and types of antibiotic resistance of Neisseria gonorrhoeae in Nanjing, China, between 1999 and 2006.

METHODS

beta-Lactamase production was determined by paper acidometric testing. Minimum inhibitory concentrations (MICs) to penicillin, ceftriaxone, tetracycline, ciprofloxacin, and spectinomycin were determined by agar plate dilution. Plasmid types were determined for TRNG and PPNG isolates by PCR.

RESULTS

One-thousand two-hundred and eight N. gonorrhoeae isolates were examined. The rate of PPNG rose from 8.0% (9 of 112) in 1999 to 57.36% (113 of 197) in 2004, and declined to 44.44% (88 of 198) in 2006. Prevalence of TRNG increased from 1.8% (2 of 112) in 1999 to 32.82% (65 of 198) in 2006. 99.23% (258 of 260) of TRNG contained the Dutch-type tetM gene and 2 strains contained the American-type tetM gene. All PPNG examined contained the Asian type plasmid. Among non-PPNG, chromosomally mediated resistance to penicillin varied from 57.84% (59 of 102) to 87.80% (72 of 82). Chromosomal resistance to ciprofloxacin (QRNG) was detected in 83.93% (94 of 112) of the strains in 1999 and 98.99% (196 of 198) in 2006. Eight spectinomycin-resistant N. gonorrhoeae strains were detected between 2001 and 2006. None of the gonococcal isolates tested was resistant to ceftriaxone but decreased susceptibility was observed in some strains.

CONCLUSIONS

Among N. gonorrhoeae strains isolated in Nanjing, China, plasmid mediated resistance including PPNG and TRNG increased significantly between 1999 and 2006. Chromosomally mediated resistance to both penicillin and ciprofloxacin was also high during this period. Spectinomycin resistance of N. gonorrhoeae was sporadic. Ceftriaxone and spectinomycin can be considered effective antimicrobial agents for the treatment of gonorrhea in Nanjing at the present time.

Update on the management of gonorrhea in adults in the United States

Gonorrhea, the second most commonly reported notifiable disease, is an important cause of cervicitis, urethritis, and pelvic inflammatory disease. The selection of appropriate therapy for gonorrhea (i.e., safe, highly effective, single dose, and affordable) is complicated by the ability of Neisseria gonorrhoeae to develop resistance to antimicrobial therapies. This article reviews the key questions and data that informed the 2006 gonorrhea treatment recommendations of the Centers for Disease Control and Prevention. Key areas addressed include the criteria used to select effective treatment for gonorrhea, the level of antimicrobial resistance at which changing treatment regimens is recommended, the epidemiology of resistance, and the use of quinolones, cephalosporins, and other classes of antimicrobials for the treatment of uncomplicated gonorrhea.

Fluoroquinolone-Resistant Neisseria gonorrhoeae in Bali, Indonesia: 2004

OBJECTIVES

In the mid-1990s, fluoroquinolones were introduced in Indonesia for the management of gonorrhea and are now part of the national recommended treatment guidelines. We recently documented introduction of ciprofloxacin-resistant Neisseria gonorrhoeae strains in female sex workers (FSWs) in Timika, Indonesia, 5 years after treating gonococcal cervicitis with ciprofloxacin and periodically monitoring antimicrobial susceptibility of isolates. To assess the importance of this observation, we determined antimicrobial susceptibilities and strain types of N. gonorrhoeae isolates from FSWs seen in a sexually transmitted infection (STI) clinic in Denpasar, Bali, Indonesia.

GOAL

The goal of this study was to determine antimicrobial susceptibilities and strain types among N. gonorrhoeae isolated from FSWs in Denpasar, Bali.

STUDY DESIGN

FSWs in Denpasar were screened for N. gonorrhoeae by standard culture. Endocervical isolates were frozen in Microbank tubes and sent to the University of California at San Francisco on dry ice. Antimicrobial susceptibility testing using a Clinical Laboratory Standards Institute-recommended agar dilution method was performed at the Centers for Disease Control and Prevention. Isolates were characterized by beta-lactamase production, antimicrobial resistance phenotypes, and auxotype/serovar class.

RESULTS

One hundred forty-seven N. gonorrhoeae isolates were characterized. All isolates were highly resistant to tetracycline (minimum inhibitory concentration, >or=16.0 microg/mL): 117 (79.1%) were beta-lactamase-positive (PP-TR), 3 (2.0%) exhibited chromosomally mediated resistance to penicillin (PenR-TRNG), and 27 (18.2%) were susceptible to penicillin (TRNG). All isolates were susceptible to ceftriaxone, cefixime, and spectinomycin; lack of interpretive criteria do not allow interpretation of susceptibilities of cefoxitin, cefpodoxime, or azithromycin. Fifty-nine (40.1%) isolates were ciprofloxacin-resistant; 35 (59.3%) of the ciprofloxacin-resistant isolates exhibited high-level resistance to ciprofloxacin (Cip-HLR; minimum inhibitory concentration, >or=4.0 microg/mL of ciprofloxacin). Three (2.0%) isolates were intermediate to ciprofloxacin. Twenty-two strain types were identified among these isolates; small clusters were identified with 3 strain types.

CONCLUSIONS

N. gonorrhoeae isolates from FSWs in Denpasar were resistant to penicillin and tetracycline; 40.1% of the isolates were fluoroquinolone-resistant. With gonorrhea prevalence of 35% at this clinic (by nucleic acid amplified tests), ongoing surveillance for antimicrobial resistance will be needed to appropriately choose treatment for infections caused by these resistant organisms.