Continuing evolution of the pattern of quinolone resistance in Neisseria gonorrhoeae isolated in Sydney, Australia

Trends in Antimicrobial Resistance Patterns in Neisseria Gonorrhoeae in Australia and New Zealand: A Meta-analysis and Systematic Review

(1) Background: The widespread development of resistance among Neisseria gonorrhoeae (NG) clinical isolates has been reported by surveillance systems around the world. This meta-analysis estimated the changes in susceptibility patterns among antibiotics under surveillance in Australia and New Zealand. (2) Methods: Articles published in English from 1980-2018, from Australia or New Zealand, that met the selection criteria were included. The meta-analysis was carried out using the R statistical software. (3) Results: In Australia, there has been decreasing susceptibility of gonococcal isolates to selected antimicrobials over time. Azithromycin (Odds Ratio (OR): 0.73; 95% Confidence Interval (CI) 0.64-0.82) and ceftriaxone (OR: 0.69; 95% CI 0.59-0.80) showed decreasing levels of susceptibility each year. Western Australia (OR: 0.76; 95% CI 0.60-0.96) and Victoria (OR: 0.74; 95% CI 0.60-0.90) also had decreasing levels of susceptibility to ceftriaxone over time compared with other states and territories. (4) Conclusions: The results highlight the need for the development of new approaches for managing cases of gonorrhoea. Improved antimicrobial stewardship, enhanced surveillance and contact tracing are needed to identify and respond to changes in antibiotic resistance in a timely manner. Increasing awareness and public health follow-up of cases can help to interrupt the cycle of infection and limit transmission.

Identifying factors that lead to the persistence of imported gonorrhoeae strains: a modelling study

OBJECTIVE

The importation of Neisseria gonorrhoeae (NG) strains from overseas is believed to be the main source of antimicrobial resistance in Australia. With recent sporadic cases of ceftriaxone-resistant gonorrhoea reported in Australia and elsewhere, we sought to model the potential for imported NG strains to persist in the men who have sex with men (MSM) population in Australia.

METHODS

We developed an individual-based model to simulate the transmission of NG in a population of urban MSM, and used this model to investigate factors contributing to the probability that an imported NG strain will persist.

RESULTS

The probability of the imported NG strain persisting as the result of a single importation event is less than 1%, but the probability increases to 1% if the imported NG strain is resistant to treatment, and further increases to 3.1% if the imported NG strain can also form mixed infections with the local NG strain. The probability of the imported NG strain persisting increases to 4.4% if there are at least three importation events per month within a 1-year period.

CONCLUSION

The imported NG strain is unlikely to persist as a result of a single importation event. However, the probability of persistence increases if the imported NG strain is resistant to treatment, can form mixed infections with the local NG strain or there are frequent importation events. Identification of the factors that determine the likelihood of persistence of an imported NG strain could contribute to our capacity to respond appropriately and in a timely fashion.

The Molecular Epidemiology and Antimicrobial Resistance of Neisseria gonorrhoeae in Australia: A Nationwide Cross-Sectional Study, 2012

BACKGROUND

 Antimicrobial resistance (AMR) by Neisseria gonorrhoeae is considered a serious global threat.

METHODS

 In this nationwide study, we used MassARRAY iPLEX genotyping technology to examine the epidemiology of N. gonorrhoeae and associated AMR in the Australian population. All available N. gonorrhoeae isolates (n = 2452) received from Australian reference laboratories from January to June 2012 were included in the study. Genotypic data were combined with phenotypic AMR information to define strain types.

RESULTS

 A total of 270 distinct strain types were observed. The 40 most common strain types accounted for over 80% of isolates, and the 10 most common strain types accounted for almost half of all isolates. The high male to female ratios (>94% male) suggested that at least 22 of the top 40 strain types were primarily circulating within networks of men who have sex with men (MSM). Particular strain types were also concentrated among females: two strain types accounted for 37.5% of all isolates from females. Isolates harbouring the mosaic penicillin binding protein 2 (PBP2)-considered a key mechanism for cephalosporin resistance-comprised 8.9% of all N. gonorrhoeae isolates and were primarily observed in males (95%).

CONCLUSIONS

 This large scale epidemiological investigation demonstrated that N. gonorrhoeae infections are dominated by relatively few strain types. The commonest strain types were concentrated in MSM in urban areas and Indigenous heterosexuals in remote areas, and we were able to confirm a resurgent epidemic in heterosexual networks in urban areas. The prevalence of mosaic PBP2 harboring N. gonorrhoeae strains highlight the ability for new N. gonorrhoeae strains to spread and become established across populations.

Gonorrhea treatment practices in the STD Surveillance Network, 2010-2012

BACKGROUND

Replacing oral treatments with ceftriaxone is a central component of public health efforts to slow the emergence of cephalosporin-resistant Neisseria gonorrhoeae in the United States; US gonorrhea treatment guidelines were revised accordingly in 2010. However, current US gonorrhea treatment practices have not been well characterized.

METHODS

Six city and state health departments in Cycle II of the STD Surveillance Network (SSuN) contributed data on all gonorrhea cases reported in 101 counties and independent cities. Treatment data were obtained through local public health surveillance and interviews with a random sample of patients. Cases were weighted to adjust for site-specific sample fractions and for differential nonresponse by age, sex, and provider type.

RESULTS

From 2010 to 2012, 135,984 gonorrhea cases were reported in participating areas, 15,246 (11.2%) of which were randomly sampled. Of these, 7,851 (51.5%) patients were interviewed. Among patients with complete treatment data, 76.8% received ceftriaxone, 16.4% received an oral cephalosporin, and 6.9% did not receive a cephalosporin; 51.9% of persons were treated with a regimen containing ceftriaxone and either doxycycline or azithromycin. Ceftriaxone treatment increased significantly by year (64.1% of patients in 2010, 79.3% in 2011, 85.4% in 2012; P = 0.0001). Ceftriaxone use varied widely by STD Surveillance Network site (from 44.6% to 95.1% in 2012).

CONCLUSIONS

Most persons diagnosed as having gonorrhea between 2010 and 2012 in the United States received ceftriaxone, and its use has increased since the release of the 2010 Centers for Disease Control and Prevention STD Treatment Guidelines.

Antibiotic resistance inNeisseria gonorrhoeaeis diminishing available treatment options for gonorrhea: some possible remedies

Gonorrhea is essentially out of control in many settings and high disease rates are coupled with the spread of multiresistant gonococci. Increases in quinolone resistance have followed loss of the penicillins and tetracyclines as useful treatments. Decreasing susceptibility to third-generation cephalosporins is also reported. Over-reliance on antibiotic treatment as a disease control measure in settings with high disease rates and poor control of antibiotic usage is a significant contributor to the antimicrobial resistance reported. Conversely, containment of resistance is more likely to be achieved when combined with disease control principles shown to be effective. However, until a higher priority is given to funding for sexually transmitted diseases, this prospect is unlikely to eventuate and the possibility of untreatable gonorrhea becomes more real.

Antimicrobial susceptibility of Neisseria gonorrhoeae strains isolated in 2004-2006 in Bangui, Central African Republic; Yaoundé, Cameroon; Antananarivo, Madagascar; and Ho Chi Minh Ville and Nha Trang, Vietnam

GOAL

To investigate the in vitro antimicrobial susceptibility of Neisseria gonorrhoeae strains isolated in 2004 and 2005 in Bangui, Central African Republic; Yaoundé, Cameroon; Antananarivo, Madagascar; and Ho Chi Minh Ville and Nha Trang, Vietnam.

STUDY DESIGN

Antimicrobial susceptibility testing was performed by both disk diffusion and agar dilution methods according to Clinical and Laboratory Standards Institute (CLSI) recommendations. Minimum inhibitory concentrations (MICs) to 5 antimicrobials (penicillin G, ceftriaxone, ciprofloxacin, spectinomycin, and tetracycline) were determined when feasible. Penicillinase-producing N. gonorrhoeae (PPNG) was analyzed by the paper acidometric method (nitrocefin test).

RESULTS

Thirty N. gonorrhoeae isolates from Bangui could be studied, 79 from Yaoundé, 126 from Antananarivo, 56 from Nha Trang, and 126 from Ho Chi Minh Ville in 2004 and 2005. Unfortunately, because of problems of electricity supply, no strains could be recovered for the determination of MICs in Yaoundé, and only 68 strains could be tested in Antananarivo and 121 in Ho Chi Minh Ville. Patterns of resistance were similar in Antananarivo, Bangui, and Yaoundé but different from those observed in Vietnam. Ciprofloxacin was highly effective in Africa, but nearly all strains in Vietnam were resistant to this drug. Overall, ceftriaxon and spectinomycin were the best antibiotics, with one strain resistant to spectinomycin in Antananrivo and one strain resistant to ceftriaxon in Ho Chi Minh Ville.

CONCLUSIONS

Ciprofloxacin remains highly efficient in Madagascar and Central Africa, ceftriaxone and spectinomycin should be used as the first-line antimicrobial agents in treating gonorrhea in Vietnam.

Importance of drug resistance in gonococci: from mechanisms to monitoring

Neisseria gonorrhoeae isolates continue to develop an impressive arsenal of resistance mechanisms to antimicrobial agents, including resistance to some of the antibiotics presently recommended for the treatment of gonococcal infections.

Distinguishing importation from diversification of quinolone-resistant Neisseria gonorrhoeae by molecular evolutionary analysis

Background

Distinguishing the recent introduction of quinolone resistant gonococci into a population from diversification of resistant strains already in the population is important for planning effective infection control strategies. We applied molecular evolutionary analyses to DNA sequences from 9 housekeeping genes and gyrA, parC and porB of 24 quinolone resistant N. gonorrhoeae (QRNG) and 24 quinolone sensitive isolates collected in Israel during 2000–2001.

Results

Phylogenetic and eBURST analyses and estimates of divergence time indicated QRNG were introduced on 3 separate occasions and underwent limited diversification by mutation, deletion and horizontal gene transfer. Reconstruction of N. gonorrhoeae demography showed a slowly declining effective strain population size from 1976 to 1993, rapid decline between 1994 and 1999, and an increase from 1999 to 2001. This is partially attributable to declining gonorrhea case rates from 1973 to 1994. Additional contributing factors are selective sweeps of antibiotic resistant gonococci and increased transmission from sex workers. The abrupt decline in the mid-1990s heralded an increased incidence of gonorrhea from 1997 to the present. The subsequent increase in effective strain population size since 1999 reflects the increased gonococcal census population and introduction of quinolone resistance strains.

Conclusion

Our study demonstrates the effective use of population genetic approaches to assess recent and historical population dynamics of N. gonorrhoeae.

Antibiotic resistance in Neisseria gonorrhoeae

The incidence of gonorrhea is increasing in developed countries and remains high elsewhere. This untenable disease burden, the complication rate in women and newborns, and the amplification of human immunodeficiency virus transmission that accompanies gonorrhea makes control of gonococcal disease a priority. However, antibiotic resistance in Neisseria gonorrhoeae has severely compromised the successful treatment of gonorrhea. Older therapies are ineffective, whereas those that remain efficacious are unaffordable in many high-incidence settings. Penicillins, tetracyclines, and newer macrolides have limited utility, and spectinomycin (and in many parts of the world, quinolones) have been withdrawn because of resistance. Of the usually recommended treatments, only the third-generation cephalosporins, and most notably ceftriaxone, have retained their efficacy, but decreased susceptibility to these antibiotics has also appeared. A sustained decrease in gonococcal disease requires an integrated approach combining improved prevention, better diagnosis, and effective treatment. Without continued commitment and effort, gonorrhea may well become untreatable.

The use of fluoroquinolones in gonorrhoea: the increasing problem of resistance

The recent re-emergence of gonorrhoea in developed countries has been accompanied by the rise and spread of gonococcal resistance to the fluoroquinolones. In the 1980s fluoroquinolones were considered an important addition to the arsenal of agents used to treat gonorrhoea. They proved to be excellent drugs for this indication, including infections caused by penicillinase-producing and tetracycline-resistant strains of Neisseria gonorrhoeae. However, as gonococci have a well-recognised potential to develop resistance to antibiotics, the first reports of reduced susceptibility to fluoroquinolones appeared a few years after their introduction. Gonococcal resistance to fluoroquinolones is now well-established in the Far East, from where it has spread to Australia, Hawaii, California and Europe. In Africa and Latin America, gonococci continue to be susceptible to fluoroquinolones.

Spatial bridges for the importation of gonorrhea and chlamydial infection

A study of heterosexuals with gonorrhea and/or chlamydial infection in King County, Washington, found that 5.2% of study participants had both local and geographically distant sex partners in the 60 days before diagnosis. Individuals who served as spatial bridges were of higher socioeconomic status and older than other patients.

BACKGROUND

Sexual mixing between distant geographic areas (spatial bridging) is important in the spread of antimicrobial resistance and new sexually transmitted disease pathogens.

GOAL

The goal was to define the extent of sexual mixing between persons with gonorrhea or chlamydial infection in King County, Washington, and persons outside the Seattle area, and to identify characteristics of persons and partnerships associated with spatial bridging.

METHODS

Patients contacted for purposes of partner notification were interviewed regarding demographics, sexual behavior, and the characteristics of their sex partners.

RESULTS

Of 2912 participants, 150 (5.2%) were spatial bridgers. Bridgers were of higher socioeconomic status than nonbridgers and more often reported concurrent partnerships. Over a 39-month period, bridgers and potential bridgers linked King County with 35 states and 13 foreign countries.

CONCLUSION

Spatial bridging could represent an important channel of transmission between geographic areas. These results highlight the need for linkage of prevention efforts across geographic boundaries.

Globalization of antimicrobial resistance: epidemiological challenges

Globalization of antimicrobial resistance is a reality, but before the relative impact of global versus local spread of resistant microorganisms can be quantified, surveillance capacity and information transfer must be greatly enhanced.

Multidrug-resistant strains of Neisseria gonorrhoeae in Greece

Eighty-seven out of 575 gonococci isolated in Greece from 1991 to 1998 belonged to serovar Bropyst and exhibited resistance to penicillin, tetracycline, erythromycin, and chloramphenicol. Conventional and molecular typing showed three clusters, A, B, and C, that were associated with networks of high- frequency transmitters (cluster A with homosexuals and clusters B and C with refugees from Eastern Europe). Study of one isolate revealed mutations in the penA, mtrR, and porB genes that may explain the multidrug-resistant phenotype.

Molecular epidemiology of Neisseria gonorrhoeae exhibiting decreased susceptibility and resistance to ciprofloxacin in Hawaii, 1991-1999

BACKGROUND

Clinically significant resistance to Centers for Disease Control and Prevention (CDC)-recommended doses of fluoroquinolones (ciprofloxacin and ofloxacin) has been reported for Neisseria gonorrhoeae. In Hawaii, fluoroquinolone-resistant gonococcal isolates were first identified in 1991.

GOAL

To assess the diversity, based on phenotypic and genotypic characterization, of gonococcal isolates exhibiting decreased susceptibility (CipI; MICs = 0.125-0.5 microg/ml) or clinically significant resistance (CipR; MICs > or = 1 microg/ml) to ciprofloxacin in Hawaii from 1991 through 1999.

STUDY DESIGN

Antimicrobial susceptibilities, auxotype/serovar (A/S) class, GyrA/ParC alteration patterns, and plasmid profiles were determined for gonococci isolated in Honolulu from 1991 through 1999 that exhibited intermediate or clinically significant resistance to ciprofloxacin. Strain phenotypes were defined by A/S class, GyrA/ParC alteration pattern, and penicillin-tetracycline resistance phenotype supplemented with plasmid profiles for beta-lactamase-producing isolates.

RESULTS

Altogether, 68 isolates exhibiting intermediate or clinically significant resistance to ciprofloxacin belonged to 23 and 19 strain phenotypes, respectively. Among the CipI and CipR isolates, 4 and 13 GyrA/ParC alterations patterns were identified, respectively. The 91,95/Asp-86 alteration pattern occurred most frequently among CipR isolates. Forty-four strain phenotypes were represented by only one isolate. In addition, seven pairs and two clusters of isolates were identified.

CONCLUSIONS

From 1991 through 1997, few gonococcal strains exhibiting intermediate or clinically significant resistance to CDC-recommended doses of fluoroquinolones were identified from Hawaii. Isolates belonged to a large number of phenotypic and genotypic types, suggesting that most cases were imported, with only a few instances in which isolate pairs indicated that secondary transmission of infections had occurred in Hawaii. Beginning in 1998, the number of CipR isolates increased markedly, and more isolates belonged to fewer phenotypic and genotypic types, suggesting either more frequent importation of fewer strain types or the possibility that the endemic spread of a few strains is beginning to occur.

A randomized trial of ciprofloxacin versus cefixime for treatment of gonorrhea after rapid emergence of gonococcal ciprofloxacin resistance in The Philippines

From 1994 through 1996-1997, high-level ciprofloxacin resistance (minimum inhibitory concentration [MIC], > or = 4.0 microg/mL) increased from 9% to 49% of gonococcal isolates recovered from consecutive female sex workers in Cebu and Manila, The Philippines (P < .01). During 1996-1997, 105 female sex workers with gonorrhea were prospectively randomized to receive treatment with oral ciprofloxacin, 500 mg, or cefixime, 400 mg, and followed for test of cure. Neisseria gonorrhoeae was reisolated within 28 days after treatment from 1 (3.8%) of 26 women given cefixime versus 24 (32.3%) of 72 women given ciprofloxacin (P < .01). Treatment failure (reisolation of pretreatment auxotype/serovar) occurred in 14 (46.7%) of 30 women infected with strains with MICs of ciprofloxacin > or = 4.0 microg/mL versus 1 (3.6%) of 28 infected by strains with MICs < 4.0 microg/mL (P < .01). High-level, clinically significant gonococcal resistance to ciprofloxacin has rapidly emerged in The Philippines, and spread of fluoroquinolone resistance through commercial sex poses a threat to control of gonorrhea and prevention of human immunodeficiency virus infection and the acquired immunodeficiency syndrome.

Quinolone Resistance in Neisseria gonorrhoeae

Single-dose oral quinolones have been recommended for gonorrhea treatment since 1989. The antimicrobial resistance surveillance system has detected several outbreaks of quinolone-resistant gonococcal infections (QRNG), and sporadic treatment failures have been reported from high-incidence areas such as southeast Asia. QRNG may result from mutations that cause structural-functional changes in DNA topoisomerase (the quinolone target enzyme) or by changes in antimicrobial transport into the bacteria. QRNG has occurred sporadically in the United States, predominantly in persons with contact to persons in southeast Asia, and has typically occurred as an epiphenomenon in persons who were treated with other regimens. Nevertheless, this entity warrants close monitoring. The emergence of QRNG is probably related to antimicrobial misuse and overuse, in particular long-term suppressive or subtherapeutic doses.

Correlation of in vitro susceptibilities to newer quinolones of naturally occurring quinolone-resistant Neisseria gonorrhoeae strains with changes in GyrA and ParC

The in vitro activities of ciprofloxacin, trovafloxacin, moxifloxacin, and grepafloxacin against 174 strains of Neisseria gonorrhoeae isolated in Sydney, Australia, were determined. The strains included 84 quinolone-less-sensitive and -resistant N. gonorrhoeae (QRNG) strains for which ciprofloxacin MICs were in the range of 0.12 to 16 microg/ml. The QRNG included strains isolated from patients whose infections were acquired in a number of countries, mostly in Southeast Asia. The gyrA and parC quinolone resistance-determining regions (QRDR) of 18 selected QRNG strains were sequenced, and the amino acid mutations observed were related to the MICs obtained. The activities of moxifloxacin and grepafloxacin against QRNG were comparable to that of ciprofloxacin. Trovafloxacin was more active than the other quinolones against some but not all of the QRNG strains. Increments in ciprofloxacin resistance occurred in a step-wise manner with point mutations initiated in gyrA resulting in amino acid alterations Ser91-to-Phe, Ser91-to-Tyr, Asp95-to-Gly, and Asp95-to-Asn. Single gyrA changes correlated with ciprofloxacin MICs in the range 0.12 to 1 microg/ml. The Ser91 changes in GyrA were associated with higher MICs and further QRDR changes. QRNG strains for which ciprofloxacin MICs were greater than 1 microg/ml had both gyrA and parC QRDR point mutations. ParC alterations were seen in these isolates only in the presence of GyrA changes and comprised amino acid changes Asp86-to-Asn, Ser87-to-Asn, Ser87-to-Arg, Ser88-to-Pro, Glu91-to-Lys, and Glu91-to-Gln. QRNG strains for which MICs were in the higher ranges had double GyrA mutations, but again only with accompanying ParC alterations. Not only did the nature and combination of GyrA and ParC changes influence the incremental increases in ciprofloxacin MICs, but they seemingly also altered the differential activity of trovafloxacin. Our findings suggest that the newer quinolones of the type examined are unlikely to be useful replacements for ciprofloxacin in the treatment of gonorrhea, particularly where ciprofloxacin MICs are high or where resistance is widespread.

Single-dose gatifloxacin compared with ofloxacin for the treatment of uncomplicated gonorrhea: a randomized, double-blind, multicenter trial

BACKGROUND

Treatment of gonorrhea is complicated by widespread resistance of Neisseria gonorrhoeae to antimicrobial agents of choice, including decreased susceptibility to ciprofloxacin.

GOAL

To demonstrate the efficacy and safety of gatifloxacin, a novel 8-methoxy fluoroquinolone antibiotic, compared with ofloxacin in treating patients with uncomplicated gonococcal infection.

STUDY DESIGN

In a double-blind, randomized (2:2:1), controlled trial, 340 men and 388 women with uncomplicated gonorrhea who were 16 years or older received a single oral dose of gatifloxacin (400 mg or 600 mg) or ofloxacin (400 mg). Primary analysis of efficacy was based on bacteriologic eradication from sites of infection. Secondary analyses examined clinical response and adverse event profiles.

RESULTS

Bacteriologic eradication rates for gatifloxacin in evaluable men with urethral gonorrhea were 99% (400 mg) and 100% (600 mg) versus 100% for ofloxacin (n = 117, 122, and 55, respectively; P = ns). Eradication rates in evaluable women with endocervical gonorrhea were 99% for both 400 mg and 600 mg gatifloxacin versus 100% for ofloxacin (n = 101, 104, and 55, respectively; P = ns). Eradication rates were 100% for both rectal (n = 43) and pharyngeal (n = 31) infection across all treatment groups. All three drug regimens were well tolerated and exhibited similar clinical response profiles.

CONCLUSION

Gatifloxacin is safe and effective as a single 400-mg or 600-mg dose for the treatment of uncomplicated gonorrhea. Similar efficacy rates were observed with the 400-mg and 600-mg doses. A single 400-mg dose can be recommended for treatment of uncomplicated gonorrhea.

Neisseria gonorrhoeae resistant to ciprofloxacin: first report in Cuba

BACKGROUND AND OBJECTIVES

The Cuban Ministry of Public Health plans to implement the syndromic approach to sexually transmitted diseases in persons with urethral or vaginal syndrome in Cuba using 500 mg ciprofloxacin as therapy. Although the emergence of clinical isolates of Neisseria gonorrhoeae with decreased susceptibility to ciprofloxacin have been sporadically detected in Cuba, there has been no report of isolates that exhibited significant resistance to this drug. This is the first report of the isolation of a N gonorrhoeae strain resistant to ciprofloxacin in Cuba.

STUDY DESIGN

Case report.

CONCLUSIONS

This case emphasizes the need for awareness regarding the potential emergence of a clinically significant resistance of N gonorrhoeae in Cuba. There is a need for continued antimicrobial susceptibility surveillance of Cuban isolates to ciprofloxacin and other fluoroquinolones.

Molecular basis of high-level ciprofloxacin resistance in Neisseria gonorrhoeae strains isolated in Denmark from 1995 to 1998

In Denmark surveillance of the in vitro susceptibility to ciprofloxacin of Neisseria gonorrhoeae was established in 1990. The proportion of N. gonorrhoeae strains with decreased susceptibility or resistance to ciprofloxacin (MIC >/= 0.06 microg/ml) was low (0.3 to 2.3%) up to 1995. Between 1995 and 1998 the rate of less-susceptible and resistant strains rose from 6.9 to 13.2%. Among ciprofloxacin-resistant strains (MIC >/= 1 microg/ml), 81% were highly resistant (MIC >/= 4 microg/ml). Thirty-five N. gonorrhoeae strains (40 isolates) for which ciprofloxacin MICs were 4 to 32 microg/ml were investigated for the frequency and patterns of mutations within the gyrA and parC genes. The quinolone resistance-determining regions of the gyrA and parC genes were amplified by PCR, and the amplicons were directly sequenced. Alterations at Ser-91 and Asp-95 in GyrA and a single or double alteration in ParC were identified in 32 strains (91%). Ser-91-to-Phe and Asp-95-to-Gly alterations in GyrA were detected in 28 strains (80%). The most common ParC alteration, Asp-86 to Asn, was found in 19 strains (54%). The strains were analyzed for genetic relationship by pulsed-field gel electrophoresis (PFGE). The analysis showed that nine strains with the same mutation pattern in the gyrA and parC genes, originating from different geographical areas over 3 years, had the same PFGE patterns after SpeI as well as NheI digestion (only one strain with one band difference in the NheI pattern), suggesting that a resistant clone had spread worldwide. The results from this study strongly suggest that double gyrA mutations plus a parC mutation(s) play an important role in the development of high-level fluoroquinolone resistance in N. gonorrhoeae.

Cost-effectiveness of management strategies for acute urethritis in the developing world

OBJECTIVE

To recommend a cost-effective approach for the management of acute male urethritis in the developing world, based on the findings of a theoretical study.

METHODS

A model was developed to assess the cost-effectiveness of three urethritis management strategies in a theoretical cohort of 1000 men with urethral syndrome. (1) All patients were treated with cefixime and doxycycline for gonococcal urethritis (GU) and nongonococcal urethritis (NGU), respectively, as recommended by WHO. (2) All patients were treated with doxycycline for NGU; treatment with cefixime was based on the result of direct microscopy of a urethral smear. (3) All patients were treated with cotrimoxazole or kanamycin for GU and doxycycline for NGU. Cefixime was kept for patients not responding to the first GU treatment. Strategy costs included consultations, laboratory diagnosis (where applicable) and drugs. The outcome was the rate of patients cured of urethritis. Cost-effectiveness was measured in terms of cost per cured urethritis.

RESULTS

Strategy costs in our model depended largely on drug costs. The first strategy was confirmed as the most effective but also the most expensive approach. Cefixime should cost no more than US$ 1.5 for the strategy to be the most cost-effective. The second strategy saved money and drugs but proved a valuable alternative only when laboratory performance was optimal. The third strategy with cotrimoxazole was the least expensive but a low follow-up visit rate, poor treatment compliance or lower drug efficacy limited effectiveness. Maximizing compliance by replacing cotrimoxazole with single-dose kanamycin had the single greatest impact on the effectiveness of the third strategy.

CONCLUSION

Our model suggested that a cost-effective approach would be to treat gonorrhoea with a single-dose antibiotic selected from locally available products that cost no more than US$ 1.5.

Concurrent gonococcal and chlamydial infection: how best to treat

Clinicians treating concurrent gonococcal and chlamydial infections have a variety of drugs to choose from. Neisseria gonorrhoeae is adept at developing resistance and the choice of antibiotic must be dictated to some extent by the patterns of resistance in the locality of the clinician. In contrast, resistance of Chlamydia trachomatis to some classes of drugs has been shown in vitro but does not appear to be clinically important at present. The success of treatment depends on patient compliance with the drug administration schedule. With these organisms, which can be carried asymptomatically, many patients are unlikely to comply with courses of antibiotics. Although single-dose therapy with azithromycin is available and established for chlamydial genital infection, it is more expensive and difficult to justify in a cash limited Healthcare system, and its efficacy for treating concurrent gonococcal infection requires further study. In patients where compliance is likely to be of concern, its use may be justified. Another major deterrent for completing antibiotic courses is the adverse effect profile. Most of the available drugs cause only minor adverse effects, in particular gastrointestinal. Ofloxacin has a better profile than doxycycline but is considerably more expensive. Newer fluoroquinolones, found to be effective in vitro, are being assessed in clinical studies. However, more evidence is required before recommending these over the tried and tested therapies.

Antimicrobial resistance in Neisseria gonorrhoeae

Despite a declining incidence of gonorrhea in much of the industrialized world, antimicrobial resistance continues to present a challenge to the treatment of gonococcal infections. Although no clinically significant resistance to the broad-spectrum cephalosporins has been identified, fluoroquinolone-resistant gonococcal strains are now prevalent in Australia and much of the Far East. Ongoing surveillance for antimicrobial resistance is crucial to obtain the information needed to choose effective empiric therapies for gonorrhea.