Multidrug-resistant Neisseria gonorrhoeae with decreased susceptibility to cefixime-Hawaii, 2001

Epidemiology of gonorrhoea: a global perspective

Although understanding the local epidemiology of gonorrhoea is critical for local efforts, understanding the multinational epidemiology may support development of national and international prevention and control policies and strategies. In this paper, current epidemiology of gonorrhoea is reviewed through an international lens and with a focus on selected populations. The World Health Organization (WHO) estimates that ~87 million new gonococcal infections occurred among people aged 15-49 years in 2016. Gonorrhoea rates are rising in many countries. Gay, bisexual and other men who have sex with men, racial or ethnic minorities, Indigenous populations and sex workers appear to bear disproportionate burdens of gonorrhoea. International travel can facilitate spread of gonorrhoea, including resistant strains, across international borders. Critical gaps in epidemiological knowledge are highlighted, including data on gonorrhoea among transgender persons and the burden of extragenital gonorrhoea. Even as further data are gathered, action - informed by currently available data - is needed now to confront this growing international threat.

Antibiotic Targets in Gonococcal Cell Wall Metabolism

The peptidoglycan cell wall that encloses the bacterial cell and provides structural support and protection is remodeled by multiple enzymes that synthesize and cleave the polymer during growth. This essential and dynamic structure has been targeted by multiple antibiotics to treat gonococcal infections. Up until now, antibiotics have been used against the biosynthetic machinery and the therapeutic potential of inhibiting enzymatic activities involved in peptidoglycan breakdown has not been explored. Given the major antibiotic resistance problems we currently face, it is crucial to identify other possible targets that are key to maintaining cell integrity and contribute to disease development. This article reviews peptidoglycan as an antibiotic target, how N. gonorrhoeae has developed resistance to currently available antibiotics, and the potential of continuing to target this essential structure to combat gonococcal infections by attacking alternative enzymatic activities involved in cell wall modification and metabolism.

Antimicrobial Drug Prescription and Neisseria gonorrhoeae Susceptibility, United States, 2005-2013

We investigated whether outpatient antimicrobial drug prescribing is associated with Neisseria gonorrhoeae antimicrobial drug susceptibility in the United States. Using susceptibility data from the Gonococcal Isolate Surveillance Project during 2005–2013 and QuintilesIMS data on outpatient cephalosporin, macrolide, and fluoroquinolone prescribing, we constructed multivariable linear mixed models for each antimicrobial agent with 1-year lagged annual prescribing per 1,000 persons as the exposure and geometric mean MIC as the outcome of interest. Multivariable models did not demonstrate associations between antimicrobial drug prescribing and N. gonorrhoeae susceptibility for any of the studied antimicrobial drugs during 2005–2013. Elucidation of epidemiologic factors contributing to resistance, including further investigation of the potential role of antimicrobial drug use, is needed.

Antibiotic susceptibility pattern of Neisseria gonorrhoeae strains isolated from five cities in India during 2013-2016

PURPOSE

Emergence of multidrug resistance in Neisseria gonorrhoeae, an STI of public health significance is the biggest challenge to gonorrhoea control. Monitoring for antimicrobial resistance is essential for the early detection of emergent drug resistance patterns.

METHODOLOGY

One hundred and twenty four N. gonorrhoeae strains were isolated between September 2013-August 2016 [82-New Delhi, 3-Pune, 3-Mumbai, 20-Secunderabad and 16-Hyderabad] to determine antimicrobial susceptibility and to compare the CLSI disc diffusion method with Etest for these strains. The results of the two methods were compared by using kappa statistics.

RESULTS

Ninety eight percent [CI: 96.2-100] of isolates were resistant to ciprofloxacin, 52 % [CI: 43.2-60.8] to penicillin, 56 % [CI: 47.2-64.7] to tetracycline and 5 % [CI: 1.2-8.8] to azithromycin. All the strains were susceptible to spectinomycin, ceftriaxone and cefixime except for two strains which showed decreased susceptibility to ceftriaxone and cefixime. Kappa scores for penicillin, azithromycin, ciprofloxacin, ceftriaxone and cefixime showed that the CLSI method had high agreement with Etest while tetracycline had substantial agreement.

CONCLUSION

Our data suggest that the disc diffusion method which is both cost effective and more feasible, can effectively be used routinely for monitoring antibiotic susceptibility in N. gonorrhoeae, in limited resource countries like India. We demonstrate the emergence of decreased susceptibility to ceftriaxone and cefixime and threshold levels of resistance to azithromycin in India. This underscores the importance of maintaining continued surveillance for antibiotic resistance in N. gonorrhoeae and a potential requirement for strategic change in guidelines in the not so distant future.

Cluster of Neisseria gonorrhoeae Isolates With High-level Azithromycin Resistance and Decreased Ceftriaxone Susceptibility, Hawaii, 2016

BACKGROUND

The Centers for Disease Control and Prevention (CDC) currently recommends dual therapy with ceftriaxone and azithromycin for gonorrhea to ensure effective treatment and slow emergence of antimicrobial resistance. Since 2013, the prevalence of reduced azithromycin susceptibility increased in the United States; however, these strains were highly susceptible to cephalosporins. We identified a cluster of Neisseria gonorrhoeae isolates with high-level azithromycin resistance, several of which also demonstrated decreased ceftriaxone susceptibility.

METHODS

Eight N. gonorrhoeae isolates collected from 7 patients on Oahu, Hawaii, seen 21 April 2016 through 10 May 2016 underwent routine Etest antimicrobial susceptibility testing by the Hawaii Department of Health. All demonstrated elevated azithromycin minimum inhibitory concentrations (MICs) >256 μg/mL and elevated ceftriaxone MICs (≥0.125 μg/mL). Isolates were sent to the University of Washington and CDC for confirmatory agar dilution testing; sequence data were sent to CDC for analysis. All patients were interviewed and treated, and when possible, partners were interviewed, tested, and treated.

RESULTS

All isolates had azithromycin MICs >16 µg/mL and 5 had ceftriaxone MICs = 0.125 µg/mL by agar dilution. All isolates were β-lactamase positive and were resistant to penicillin, tetracycline, and ciprofloxacin. Genomic analysis revealed genetic relatedness. No patients reported recent travel or antibiotic use, and no male patients reported male sex partners. All patients were successfully treated.

CONCLUSIONS

This cluster of genetically related gonococcal isolates with decreased ceftriaxone susceptibility and high-level azithromycin resistance may bring the threat of treatment failure in the United States with the current recommended dual therapy one step closer.

Worldwide susceptibility rates of Neisseria gonorrhoeae isolates to cefixime and cefpodoxime: a systematic review and meta-analysis

BACKGROUND

Neisseria gonorrhoeae (NG) infection is a serious public health problem. The third-generation extended-spectrum cephalosporins (ESCs) have been used as the first-line treatment for NG infection for almost three decades. However, in recent years, treatment failures with the oral third-generation ESCs have been reported worldwide. This study aimed to estimate worldwide susceptibility rates of NG to cefixime and cefpodoxime by analyzing data from all relevant published studies.

METHODOLOGY/PRINCIPAL FINDINGS

Two researchers independently searched five databases to identify studies on susceptibilities of NG to cefixime and cefpodoxime published between January 1, 1984 and October 15, 2012. A fixed-effect model was used to perform group analysis, and a χ2 test was employed to make subgroup comparison. Publication bias was assessed with the Begg rank correlation test. The pooled susceptibility rate of NG isolates to cefixime was 99.8% (95% CI: 99.7%-99.8%). The cefixime susceptibility rate of NG isolates from men was significantly lower than that from patients without information of gender or from men and women; the susceptibility rate of NG isolates from Asia was significantly lower than that from other continents; and the susceptibility rate of NG isolates collected before or during 2003 was significantly higher than that after 2003. The pooled susceptibility rate of NG isolates to cefpodoxime was 92.8% (95% CI: 89.0%-95.3%), which was lower than that to cefixime (92.8% vs. 99.8%, χ2 = 951.809, P<0.01).

CONCLUSIONS

The susceptibility rate of NG isolates to cefixime varied with the gender of patients and geographical location from which NG isolates were collected, and declined with time. The reported lower susceptibility rate of NG isolates to cefixime and associated treatment failures, as well as the emergence of NG strains with cephalosporin resistance call for the more effective control of NG infection and the development of new antibiotics.

The role of core groups in the emergence and dissemination of antimicrobial-resistant N gonorrhoeae

Core groups contain individuals who are regularly infected with Neisseria gonorrhoeae and are able to transmit their infection to a large number of sexual partners. Classical core groups, such as sex workers and their male partners, or men who have sex with men (MSM), have contributed to the emergence and spread of antimicrobial-resistant N gonorrhoeae over many years. Sex workers and their clients were the most important core group driving the dissemination of penicillinase-producing N gonorrhoeae in the 1970s. Such individuals have continued to contribute to penicillinase-producing N gonorrhoeae outbreaks as well as to the subsequent emergence of gonococcal resistance to fluoroquinolones, macrolides, spectinomycin and cephalosporins in various settings. MSM have been a very important core group since the 1980s, first with the spread of TetM-expressing N gonorrhoeae and, second, with the dissemination of fluoroquinolone-resistant N gonorrhoeae. MSM-associated sexual networks have most recently been critical to the spread of gonococci resistant to third generation extended spectrum cephalosporins, including cefixime and ceftriaxone. Individuals within other core groups have also been linked to the transmission of antimicrobial-resistant gonorrhoea, such as military personnel, travellers, drug users, young adults, older men and members of street gangs. Understanding core behaviours and their geospatial clustering is essential for an optimal public health response to the rising prevalence of antimicrobial-resistant gonorrhoea. Furthermore, rapid and effective treatment of N gonorrhoeae infections in core individuals and their sexual partners should be a priority for gonorrhoea control programmes.

Moving forward in tackling antimicrobial resistance: WHO actions

Although the key focus of this supplement is related to antimicrobial resistance (AMR) in a sexually transmitted infection, Neisseria gonorrhoeae, the purpose of this article is to highlight the wider public health impact of AMR and the need for different disciplines of health to coordinate and collaborate in their selection and use of antimicrobial agents. AMR is being detected in health areas ranging from simple drugs used to treat common bacterial infections to the complex formulations used to treat tuberculosis, malaria and HIV infection, and on all continents. Tackling and containing AMR present an ordeal to international and national health authorities on many fronts. In June 2012, WHO launched the WHO Global Action Plan to Control the Spread and Impact of Antimicrobial Resistance in Neisseria gonorrhoeae with a vision to enhance the global response to the prevention, diagnosis and control of N gonorrhoeae infection and mitigate the health impact of AMR through enhanced, sustained, evidence-based and collaborative multisectoral action. This global action plan is positioned within a long-standing commitment of WHO to the issue of AMR with the launch of the Global Strategy on AMR in 2001 and World Health Day on AMR in 2011.

Severe conjunctivitis due to multidrug-resistant Neisseria gonorrhoeae and adenovirus 53 coinfection in a traveler returning from Thailand

A male traveler returning from Thailand with severe bilateral conjunctivitis was tested for causative pathogens by culture and polymerase chain reaction in late 2010. The culturally grown Neisseria gonorrhoeae strain was resistant against penicillin, ciprofloxacin, and tetracycline. The patient was also found to have an eye infection with the unusual and likely recombinant adenovirus type 53. Besides multidrug-resistant gonococcal strains the unusual adenovirus strain is found circulating in Asia and both pathogens may be a risk for travelers.

Neisseria gonorrhoeae non-susceptible to cephalosporins and quinolones in Northwest Ethiopia

BACKGROUND

The occurrence of antibiotic resistant Neisseria gonorrhoeae isolates is a serious public health problem in different corners of the globe. The objective of this study was to analyze the antimicrobial susceptibility pattern of N. gonorrhoeae in Northwest Ethiopia.

METHODS

This was a retrospective study of N. gonorrhoeae isolated from genital swabs of patients referred to the Amhara Regional Health Research Laboratory between September 2006 and June 2012 in Bahir Dar, Ethiopia. A structured check list was used to collect socio-demographic and laboratory variables. Data were analyzed using SPSS software version 16.

RESULTS

Out of 352 genital specimens processed, 29 clinical strains of N. gonorrhoeae were identified. The percentage of N. gonorrhoeae isolates non-susceptible to ceftriaxone, ciprofloxacin, tetracycline and penicillin G was 27.8%, 40.9%, 92.6% and 94.4% respectively. Twenty percent of the isolates were found to be non-susceptible to both ceftriaxone and ciprofloxacin. Non-susceptibility to an injectable cephalosporin and any two of quinolones, penicillins or tetracyclines was observed in 27.8% of the isolates. The percentage of N. gonorrhoeae which were non-susceptible to tetracycline or penicillin G was high throughout the study period. However, the percentage of fluoroquinolone or cephalosporine non-susceptible strains showed an increasing trend.

CONCLUSIONS

A high percentage of N. gonorrhoeae isolated from genital specimens in Northwest Ethiopia are non-susceptible to an injectable cephalosporin and any two of quinolones, penicillins or tetracyclines. Treatment of gonorrhea in the study area needs to be guided by antibiotic susceptibility testing of isolates.

Gonococcal susceptibility to cephalosporins--Hawaii, 2003 to 2011

Among gonococcal isolates examined at the Hawaii State Laboratory Division from 2003 to 2011, the prevalence of elevated cefixime minimum inhibitory concentrations (MICs; ≥0.064 μg/mL) and elevated cefpodoxime MICs (≥0.19 μg/mL) increased over time. In contrast, few isolates exhibited elevated ceftriaxone MICs (≥0.094 μg/mL), and the prevalence of elevated ceftriaxone MICs did not change.

Molecular monitoring and determination of N. gonorrhoeae sensitivity to antimicrobial drugs as tools to control the propagation of gonococcal infection in the Arkhangelsk Region

As a result of studying the sensitivity indices concerning antimicrobial drugs (AMD) for 203 strains of N. gonorrhoeae obtained from patients suffering from the gonococcal infection in the Arkhangelsk region, it was established that the trends of N. gonorrhoeae strains propagation, which are resistant to AMD, match the trends in Russia in general. Ceftriaxone is the drug of choice to treat the gonococcal infection in the territory of the region. It was observed that N. gonorrhoeae strains started developing resistance to the AMD in the territory of the region. The authors conducted a study of 51 N. Gonorrhoeae strains obtained from patients suffering from the gonococcal infection in 2011 using molecular epidemiology methods (sequence and phylogenetic analysis). Heterogeneity in the sample of the N. gonorrhoeae strains circulating in the territory of the Arkhangelsk region as well as high rate of their genetic variability were revealed. It was noted that N. gonorrhoeae strains, which are unique for this geographic region (dominating sequence types No. 343, 5042, 1523, 1152, 387, 6238, 5825 and 6234 as well as single sequence types), are registered in the territory of the Arkhangelsk region. The authors demonstrated the possibility to use molecular methods (PCR and sequence analysis) for individual identification of infection sources and sexual partners of patients suffering from the gonococcal infection and for the purposes of epidemiological monitoring. The authors established associations between the fact that the N. gonorrhoeae strains obtained from patients suffering from the gonococcal infection in the Arkhangelsk region belong to sequence types No. 343, 285, 2625 and 6237, and their multi-resistance, which demands a thorough examination to determine the treatment tactics for such patients. Taking into consideration the results of these studies, the authors prepared recommendations on how to control the propagation of the gonococcal infection in the territory of the Arkhangelsk region.

Cephalosporin and azithromycin susceptibility in Neisseria gonorrhoeae isolates by site of infection, British Columbia, 2006 to 2011

BACKGROUND

Widespread resistance of Neisseria gonorrhoeae to penicillin, tetracycline, and fluoroquinolones has challenged effective treatment and control; recent international case reports of cefixime, ceftriaxone, and azithromycin resistance suggest that the remaining treatment options are now additionally threatened. To explore trends in antimicrobial susceptibility of N. gonorrhoeae, we reviewed provincial laboratory data from British Columbia, 2006 to 2011.

METHODS

Susceptibility testing was performed for all N. gonorrhoeae isolates detected in-house or forwarded to the reference laboratory. Resistance or intermediate resistance (nonsusceptibility) was defined by standard breakpoints for penicillin, tetracycline, ciprofloxacin, and spectinomycin. Elevated minimum inhibitory concentrations (MICs) at serial dilutions of 0.064 μg/mL or greater were explored for cefixime/ceftriaxone and 0.5 μg/mL or greater for azithromycin. Nonsusceptibility/elevated MIC was compared by year, site of infection, sex, and age.

RESULTS

A total of 1837 isolates representing 22% of all reported gonorrhea cases were analyzed. Nonsusceptibility to penicillin was established at baseline. Nonsusceptibility to tetracycline and ciprofloxacin increased over the study period, reaching 96% and 36%, respectively, in 2011. Sixteen isolates (1%) had a cefixime MIC of 0.25 μg/mL (none ≥0.5), none had a ceftriaxone MIC of 0.25 μg/mL or greater, and 15 (1%) had an azithromycin MIC of 2.0 μg/mL or greater. Elevated MIC of these agents showed an increasing trend over time. Nonsusceptibility and elevated MIC were consistently highest at the rectal and pharyngeal sites and higher in isolates from males, including when stratified to the pharyngeal site.

INTERPRETATION

Increases in elevated MIC of cefixime/ceftriaxone/azithromycin were superimposed on a background of established resistance to penicillin, tetracycline, and ciprofloxacin and may signal impending gonococcal resistance to first-line treatments. Ongoing surveillance will inform timely shifts in treatment recommendations.

Mutation in ribosomal protein S5 leads to spectinomycin resistance in Neisseria gonorrhoeae

Spectinomycin remains a useful reserve option for therapy of gonorrhea. The emergence of multidrug-resistant Neisseria gonorrhoeae strains with decreased susceptibility to cefixime and to ceftriaxone makes it the only medicine still effective for treatment of gonorrhea infection in analogous cases. However, adoption of spectinomycin as a routinely used drug of choice was soon followed by reports of spectinomycin resistance. The main molecular mechanism of spectinomycin resistance in N. gonorrhoeae was C1192T substitution in 16S rRNA genes. Here we reported a Thr-24→Pro mutation in ribosomal protein S5 (RPS5) found in spectinomycin resistant clinical N. gonorrhoeae strain, which carried no changes in 16S rRNA. In a series of experiments, the transfer of rpsE gene allele encoding the mutant RPS5 to the recipient N. gonorrhoeae strains was analyzed. The relatively high rate of transformation [ca. 10⁻⁵ colony-forming units (CFUs)] indicates the possibility of spread of spectinonycin resistance within gonococcal population due to the horizontal gene transfer (HGT).

Identification of amino acids conferring high-level resistance to expanded-spectrum cephalosporins in the penA gene from Neisseria gonorrhoeae strain H041

The recent identification of a high-level-ceftriaxone-resistant (MIC = 2 to 4 μg/ml) isolate of Neisseria gonorrhoeae from Japan (H041) portends the loss of ceftriaxone as an effective treatment for gonococcal infections. This is of grave concern because ceftriaxone is the last remaining option for first-line empirical antimicrobial monotherapy. The penA gene from H041 (penA41) is a mosaic penA allele similar to mosaic alleles conferring intermediate-level cephalosporin resistance (Ceph(i)) worldwide but has 13 additional mutations compared to the mosaic penA gene from the previously studied Ceph(i) strain 35/02 (penA35). When transformed into the wild-type strain FA19, the penA41 allele confers 300- and 570-fold increases in the MICs for ceftriaxone and cefixime, respectively. In order to understand the mechanisms involved in high-level ceftriaxone resistance and to improve surveillance and epidemiology during the potential emergence of ceftriaxone resistance, we sought to identify the minimum number of amino acid alterations above those in penA35 that confer high-level resistance to ceftriaxone. Using restriction fragment exchange and site-directed mutagenesis, we identified three mutations, A311V, T316P, and T483S, that, when incorporated into the mosaic penA35 allele, confer essentially all of the increased resistance of penA41. A311V and T316P are close to the active-site nucleophile Ser310 that forms the acyl-enzyme complex, while Thr483 is predicted to interact with the carboxylate of the β-lactam antibiotic. These three mutations have thus far been described only for penA41, but dissemination of these mutations in other mosaic alleles would spell the end of ceftriaxone as an effective treatment for gonococcal infections.

Mechanisms of the formation of Neisseria gonorrhoeae resistance to cephalosporins

The authors provide a review of the present-day literature data on the issues of studying the mechanisms of the formation of Neisseria gonorrhoeae resistance to third-generation cephalosporins. Studies in this field are needed in connection with the occurrence of strains resistant to third-generation cephalosporins as well as low-sensitivity strains. The authors emphasize the importance of mutations in porB, penA, mtrR, penB and ponA genes in the development of Neisseria gonorrhoeae resistance to β-lactam antibiotics and describe the prospects of studying the mosaic structure of the penA gene encoding the РВР2 protein as well as spatial structure of this protein.

Antimicrobial resistant gonorrhea in Atlanta: 1988-2006

Gonococcal isolates (n = 4336) were collected from men with urethritis at the Fulton County STD Clinic between 1988 and 2006. Antimicrobial susceptibility was performed by agar dilution. Increasing numbers of isolates from men who have sex with men and with fluoroquinolone resistance were noted. New antimicrobials effective against gonorrhea are urgently needed.

Neisseria gonorrhoeae with high-level resistance to azithromycin: case report of the first isolate identified in the United States

We report on the first Neisseria gonorrhoeae isolate in the United States identified with high-level resistance to azithromycin. This report discusses the epidemiologic case investigation, the molecular studies of resistance-associated mutations and N. gonorrhoeae multiantigen sequence typing, and challenges posed by emerging gonococcal antimicrobial resistance.

Gonorrhea infection in women: prevalence, effects, screening, and management

Gonorrhea is a set of clinical conditions resulting from infection with the sexually-acquired bacterial pathogen Neisseria gonorrhoeae. Acquisition may involve multiple mucosal sites in the lower female genital tract, including the urethra, cervix, Bartholin’s and Skene’s glands, as well as the anorectal canal, pharynx, and conjunctivae. It may spread to the upper genital tract, uterine tubes, abdominal cavity, and other systemic sites. Gonorrhea is the second most commonly reported sexually-transmitted infection in the US and rates are higher among women than men. Women and infants are affected disproportionately by gonorrhea, because early infection may be asymptomatic and also because extension of infection is often associated with serious sequelae. Screening is critical for infection identification and the prevention or limitation of upper genital tract spread, and horizontal and vertical transmission. Routine genital screening is recommended annually for all sexually active women at risk for infection, including women aged < 25 years and older women with one or more of the following risks: a previous gonorrhea infection, the presence of other sexually transmitted diseases, new or multiple sex partners, inconsistent condom use, commercial sex work, drug use, or human immunodeficiency virus infection with sexual activity or pregnancy. Pharyngeal gonococcal infections are common in adolescents, and direct culture screening is necessary to identify affected individuals. Nucleic acid amplification tests (NAATs) are considered the standard for screening and diagnosis. Although urine NAAT testing is most commonly used, there is growing support for vaginal swabs collected by providers or patients themselves. Resistance to all antibiotics currently recommended for the treatment of gonorrhea has been documented and complicates therapeutic strategies. The Centers for Disease Control and Prevention recommend treatment of gonorrhea with a single class of drugs, ie, the cephalosporins.

Cephalosporin Resistance in Neisseria gonorrhoeae

Gonorrhea, a disease of public health importance, not only leads to high incidence of acute infections and complications but also plays a major role in facilitating human immunodeficiency virus (HIV) acquisition and transmission. One of the major public health needs for gonorrhea control is appropriate, effective treatment. However, treatment options for gonorrhea are diminishing as Neisseria gonorrhoeae have developed resistance to several antimicrobial drugs such as sulfonamides, penicillin, tetracyclines and quinolones. Antimicrobial resistance (AMR) surveillance of N. gonorrhoeae helps establish and maintain the efficacy of standard treatment regimens. AMR surveillance should be continuous to reveal the emergence of new resistant strains, monitor the changing patterns of resistance, and be able to update treatment recommendations so as to assist in disease control. Current treatment guidelines recommend the use of single dose injectable or oral cephalosporins. The emergence and spread of cephalosporin resistant and multi drug resistant N. gonorrhoeae strains, represents a worrying trend that requires monitoring and investigation. Routine clinical laboratories need to be vigilant for the detection of such strains such that strategies for control and prevention could be reviewed and revised from time to time. It will be important to elucidate the genetic mechanisms responsible for decreased susceptibility and future resistance. There is also an urgent need for research of safe, alternative anti-gonococcal compounds that can be administered orally and have effective potency, allowing high therapeutic efficacy (greater than 95.0% cure rate).

Cephalosporins of the third generation for the treatment of gonorrhea

The article presents the data on antibiotic resistance and N. gonorrhoeae mechanisms for developing resistance to antimicrobial drugs belonging to different pharmacologic groups and applied for causal treatment of gonorrhea. The article proves the key problem related to the treatment of gonococcal infection in Russia lies in the prevalence of strains being resistant to most of the antibacterial drugs that used to be applied in the clinical practice on a broad scale and efficiently. So, cephalosporins of the third generation are presently the only drug type that N. gonorrhoeae remains sensitive to. Their application ensures the maximum efficacy against the gonococcal infection. According to the presentday international recommendations complying with the WHO criteria as well as accumulated experience, cefixime, a drug belonging to cephalosporins of the third generation, can be a drug of choice for the antibacterial therapy of gonorrhea along with ceftriaxon.

Cefixime-resistant Neisseria gonorrhoeae in the UK: a time to reflect on practice and recommendations

A 40-year-old man who has sex with men (MSM) with urethral gonorrhoea failed to respond to treatment with 400 mg cefixime orally. Laboratory isolation of the post-treatment strain showed a minimum inhibitory concentration of ≥0.25 mg/L, which is a level of tolerance to cefixime that has not been previously documented in the UK. This case illustrates the importance of assessing all patients after treatment for gonorrhoea so that treatment failure and antibiotic resistance can be identified. It is vital that gonorrhoea culture continues to be attempted from all infected individuals to enable accurate diagnosis and antibiotic sensitivities. We also recommend that laboratories test for cefixime sensitivity routinely, given that it is one of the most commonly prescribed treatments for gonorrhoea.

Molecular analysis of antimicrobial resistance mechanisms in Neisseria gonorrhoeae isolates from Ontario, Canada

Surveillance of gonococcal antimicrobial resistance and the molecular characterization of the mechanisms underlying these resistance phenotypes are essential in order to establish correct empirical therapies, as well as to describe the emergence of new mechanisms in local bacterial populations. To address these goals, 149 isolates were collected over a 1-month period (October-November 2008) at the Ontario Public Health Laboratory, Toronto, Canada, and susceptibility profiles (8 antibiotics) were examined. Mutations in previously identified targets or the presence of some enzymes related to resistance (r), nonsusceptibility (ns) (resistant plus intermediate categories), or reduced susceptibility (rs) to the antibiotics tested were also studied. A significant proportion of nonsusceptibility to penicillin (PEN) (89.2%), tetracycline (TET) (72.3%), ciprofloxacin (CIP) (29%), and macrolides (erythromycin [ERY] and azithromycin; 22.3%) was found in these strains. Multidrug resistance was observed in 18.8% of the collection. Although all the strains were susceptible to spectinomycin and extended-spectrum cephalosporins (ESC) (ceftriaxone and cefixime), 9.4% of them displayed reduced susceptibility to extended-spectrum cephalosporins. PBP 2 mosaic structures were found in all of these ESC(rs) isolates. Alterations in the mtrR promoter, MtrR repressor (TET(r), PEN(ns), ESC(rs), and ERY(ns)), porin PIB (TET(r) and PEN(ns)), and ribosomal protein S10 (TET(r)) and double mutations in gyrA and parC quinolone resistance-determining regions (QRDRs) (CIP(r)) were associated with and presumably responsible for the resistance phenotypes observed. This is the first description of ESC(rs) in Canada. The detection of this phenotype indicates a change in the epidemiology of this resistance and highlights the importance of continued surveillance to preserve the last antimicrobial options available.

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.

Various penA mutations together with mtrR, porB and ponA mutations in Neisseria gonorrhoeae isolates with reduced susceptibility to cefixime or ceftriaxone

OBJECTIVES

To examine mutations within the penA, mtrR, porB, ponA and pilQ genes of Neisseria gonorrhoeae to determine their contribution to cephalosporin resistance.

METHODS

A total of 46 N. gonorrhoeae isolates with reduced susceptibility to cefixime or ceftriaxone (MICs > or = 0.12 mg/L) and two susceptible isolates were selected. The full sequence of penA and partial sequences previously reported as hot mutation sites of the other genes were analysed. Genotyping by N. gonorrhoeae multiantigen sequence typing (NG-MAST) was also performed.

RESULTS

A mosaic penicillin-binding protein 2 (PBP 2) was found in a single isolate that exhibited the highest cefixime MIC (0.5 mg/L). The majority of the isolates with reduced susceptibility to cephalosporins contained non-mosaic PBP 2 sequences, of which PBP 2 pattern XIII was most common (28/46). All isolates with reduced susceptibility to cephalosporins also had mtrR and porB mutations. Two susceptible isolates had the PBP 2 pattern XIV and an incomplete MtrR protein, which was a new mutation. Isolates with identical PBP 2 patterns comprised multiple NG-MAST sequence types.

CONCLUSIONS

Reduced susceptibility of N. gonorrhoeae to ceftriaxone and cefixime was associated with diverse penA mutations, particularly PBP 2 pattern XIII containing an Ala-501-->Val substitution, together with mtrR and porB mutations. The existence of only one strain having the mosaic penA sequence indicated that ceftriaxone and cefixime resistance in Korea is mostly not associated with a mosaic penA sequence. Highly heterogeneous NG-MAST sequence types excluded the clonal expansion of a particular subtype.

Meeting the public health challenge of multidrug- and extensively drug-resistant Neisseria gonorrhoeae

Globally, antimicrobial resistance (AMR) in Neisseria gonorrhoeae is increasing in prevalence, both within and across antibiotic classes, including extended-spectrum cephalosporins, raising concerns that gonorrhea may become untreatable in certain circumstances. The AMR surveillance that is essential to optimize standard treatments is often lacking or of poor quality in countries with high disease rates. Recent initiatives by the WHO to enhance global AMR surveillance that focus on multidrug- and extensively drug-resistant N. gonorrhoeae through revision of surveillance standards and use of a new panel of N. gonorrhoeae control strains are described. Keys to meeting these new challenges posed by gonococcal AMR remain the reduction in global burden of gonorrhea combined with implementation of wider strategies for general AMR control, and better understanding of mechanisms of emergence and spread of AMR.

Strain typing and antimicrobial resistance of fluoroquinolone-resistant Neisseria gonorrhoeae causing a California infection outbreak

Antimicrobial-resistant Neisseria gonorrhoeae is an emerging public health problem as a result of the alarming limitation in treatment options. We examined an outbreak in California of fluoroquinolone-resistant Neisseria gonorrhoeae (QRNG) by evaluation of a combination of routine isolates from the Gonococcal Isolate Surveillance Project and isolates collected by expanded surveillance performed between April 2000 and June 2002. QRNG isolates were characterized by two methods: (i) determination of a combination of antibiogram, auxotype, serovar, Lip type, and patterns of amino acid alteration in the quinolone resistance-determining region of GyrA and ParC (ASLGP) and (ii) pulsed-field gel electrophoresis (PFGE). Strain typing was used to describe the QRNG outbreak strains and the associated antimicrobial resistance profiles. Among 79 isolates that were completely characterized, we identified 20 different ASLGP strain types, and 2 of the types were considered to belong to outbreak strains that comprised 65% (51/79) of the isolates. By PFGE typing, there were 24 different strain types, and 4 of these were considered outbreak types and comprised 66% (52/79) of the isolates. The overall agreement between the typing methods in distinguishing outbreak strains and non-outbreak strains was 84% (66/79). The most common QRNG ASLGP strain type had chromosomally mediated resistance to penicillin and tetracycline and an azithromycin MIC of 0.5 microg/ml. The occurrence of an outbreak caused by QRNG strains that could fail to be eradicated by most antibiotic classes reinforces the serious problem with antimicrobial resistance in Neisseria gonorrhoeae that the public health system faces. Adherence to a regimen with the recommended antibiotics at the appropriate dose is critical, and monitoring for antimicrobial susceptibility needs to be actively maintained to adapt treatment guidelines appropriately.

Genetics of chromosomally mediated intermediate resistance to ceftriaxone and cefixime in Neisseria gonorrhoeae

All strains of Neisseria gonorrhoeae with reduced susceptibility to ceftriaxone and cefixime (cephalosporin-intermediate-resistant [Ceph(i)] strains) contain a mosaic penA allele encoding penicillin-binding protein 2 (PBP 2) with nearly 60 amino acid differences compared to the sequence of wild-type PBP 2, together with a set of resistance determinants (i.e., mtrR, penB, and/or ponA1) that are required for high-level penicillin resistance. To define the individual contributions of these determinants to reduced susceptibility to ceftriaxone and cefixime, we created isogenic strains containing the mosaic penA allele from the Ceph(i) strain 35/02 (penA35) together with one or more of the other resistance determinants and determined the MICs of penicillin G, ceftriaxone, and cefixime. The majority of cefixime resistance is conferred by the penA35 allele, with only a small contribution coming from mtrR and penB, whereas ceftriaxone resistance is nearly equally dependent upon mtrR and penB. Unlike high-level penicillin resistance, the ponA1 allele does not appear to be important for Ceph(i). A strain containing all four determinants has increased resistance to ceftriaxone and cefixime but not to the levels that the donor Ceph(i) strain does, suggesting that Ceph(i) strains, similar to high-level-penicillin-resistant strains, contain an additional unknown determinant that is required to reach donor levels of resistance. Our data also suggest that the original Ceph(i) strains arose from the transformation of penA genes from commensal Neisseria species into a penicillin-resistant strain already harboring mtrR, penB, ponA1, and the unknown gene(s) involved in high-level penicillin resistance.

The use of cephalosporins for gonorrhea: the impending problem of resistance

Gonorrhea remains an important clinical and public health problem throughout the world. Gonococcal infections have historically been diagnosed by Gram stain and culture but are increasingly diagnosed through nucleic acid tests, thereby eliminating the opportunity for antimicrobial susceptibility testing. Gonococcal infections are typically treated with single-dose therapy with an agent found to cure > 95% of cases. Unfortunately, the gonococcus has repeatedly developed resistance to antimicrobials including sulfonamides, penicillin, tetracyclines and fluoroquinolones. This has now left third-generation cephalosporins as the lone class of antimicrobials recommended as first-line therapy for gonorrhea in some regions. However, resistance to oral third-generation cephalosporins has emerged and spread in Asia, Australia and elsewhere. The mechanism of this resistance seems to be associated with a mosaic penicillin binding protein (penA) in addition to other chromosomal mutations previously found to confer resistance to beta-lactam antimicrobials (ponA, mtrR, penB, pilQ). Few good options exist or are in development for treating cephalosporin-resistant isolates, as most have had multidrug resistance. Preventing the spread of resistant isolates will depend on ambitious antimicrobial management programs, strengthening and expanding surveillance networks, and through effective sexually transmitted disease control and prevention.

Sexually transmitted diseases diagnosed among travelers returning from the tropics

OBJECTIVES

Data are lacking on the spectrum of sexually transmitted diseases (STDs) diagnosed in returning travelers.

STUDY DESIGN

All consecutive travelers consulting our tropical unit between November 1, 2002 and October 31, 2003 were included if they presented within 1 month after their return from the tropics, with mucocutaneous signs suggesting STDs.

RESULTS

Forty-nine patients (12 women and 37 men; median age 36.4 y, 35 heterosexuals) were included. Four patients had traveled with their usual sexual partner and 45 patients had casual sex while abroad (31 with locals and 14 with other tourists). The main diagnoses were gonococcal urethritis (n = 18), herpes simplex virus 2 infection (n = 12), urethritis of undetermined origin (n = 9), Chlamydia trachomatis infection (n = 4), primary syphilis (n = 4), and primary human immunodeficiency virus infection (n = 2).

CONCLUSIONS

These results illustrate the broad spectrum of STDs contracted by travelers to the tropics. They suggest the need to also inform travelers of the risks of STD and to promote the use of condoms in case of casual sex while abroad.

Crystal structures of penicillin-binding protein 2 from penicillin-susceptible and -resistant strains of Neisseria gonorrhoeae reveal an unexpectedly subtle mechanism for antibiotic resistance

Penicillin-binding protein 2 (PBP2) from N. gonorrhoeae is the major molecular target for beta-lactam antibiotics used to treat gonococcal infections. PBP2 from penicillin-resistant strains of N. gonorrhoeae harbors an aspartate insertion after position 345 (Asp-345a) and 4-8 additional mutations, but how these alter the architecture of the protein is unknown. We have determined the crystal structure of PBP2 derived from the penicillin-susceptible strain FA19, which shows that the likely effect of Asp-345a is to alter a hydrogen-bonding network involving Asp-346 and the SXN triad at the active site. We have also solved the crystal structure of PBP2 derived from the penicillin-resistant strain FA6140 that contains four mutations near the C terminus of the protein. Although these mutations lower the second order rate of acylation for penicillin by 5-fold relative to wild type, comparison of the two structures shows only minor structural differences, with the positions of the conserved residues in the active site essentially the same in both. Kinetic analyses indicate that two mutations, P551S and F504L, are mainly responsible for the decrease in acylation rate. Melting curves show that the four mutations lower the thermal stability of the enzyme. Overall, these data suggest that the molecular mechanism underlying antibiotic resistance contributed by the four mutations is subtle and involves a small but measurable disordering of residues in the active site region that either restricts the binding of antibiotic or impedes conformational changes that are required for acylation by beta-lactam antibiotics.

Ceftibuten resistance and treatment failure of Neisseria gonorrhoeae infection

Neisseria gonorrhoeae infections have been empirically treated in Hong Kong with a single oral 400-mg dose of ceftibuten since 1997. Following anecdotal reports of the treatment failure of gonorrhea with oral extended-spectrum cephalosporins, the current study was undertaken to determine the antimicrobial susceptibility pattern and molecular characteristics of isolates of N. gonorrhoeae among patients with putative treatment failure in a sexually transmitted disease clinic setting. Between October 2006 and August 2007, 44 isolates of N. gonorrhoeae were studied from patients identified clinically to have treatment failure with empirical ceftibuten. The ceftibuten MICs for three strains were found to have been 8 mg/liter. These strains were determined by N. gonorrhoeae multiantigen sequence typing to belong to sequence type 835 (ST835) or the closely related ST2469. The testing of an additional eight archived ST835 strains revealed similarly elevated ceftibuten MICs. The penA gene sequences of these 11 isolates all had the mosaic pattern previously described as pattern X. Of note is that the ceftriaxone susceptibility results of these strains all fell within the susceptible range. It is concluded that ceftibuten resistance may contribute to the empirical treatment failure of gonorrhea caused by strains harboring the mosaic penA gene, which confers reduced susceptibility to oral extended-spectrum cephalosporins. Screening for such resistance in the routine clinical laboratory may be undertaken by the disk diffusion test. The continued monitoring of antimicrobial resistance and molecular characteristics of N. gonorrhoeae isolates is important to ensure that control and prevention strategies remain effective.

Trends of sexually transmitted diseases and antimicrobial resistance in Neisseria gonorrhoeae

Sexually transmitted diseases (STDs), especially HIV infection, gonococcal infection and genital chlamydial infections are increasing all over the world. UNAIDS recently reported that the number of HIV/AIDS patients had been increasing and the highest prevalence was found in African countries, followed by Caribbean, Asian and Eastern European countries. HIV infection has also been gradually increasing in Japan. In non-HIV STDs, genital chlamydial infections are increasing worldwide also. On the contrary, gonococcal infections have been decreasing in many countries except Asian countries. N. gonorrhoeae has been changing in its infecting sites. The pharynx is the most important infecting site, because gonococcal infection in the pharynx may be one of the causes of the wide spread of N. gonorrhoeae. Antimicrobial-resistant N. gonorrhoeae has wide distribution throughout the world. For example, penicillin-resistant N. gonorrhoeae is prevalent in various part of the world, and fluoroquinolone-resistant N. gonorrhoeae is prevalent mainly in Asia. In addition to penicillin, tetracycline and fluoroquinolone resistance, N. gonorrhoeae acquired resistance to almost all of the cephalosporins except for ceftriaxone and cefodizime in Japan. Although there is no resistant strain to ceftriaxone, cefodizime and spectinomycin, 1.0 g single dose of ceftriaxone is considered to be the most suitable regimen for the treatment of gonococcal infection including the pharyngeal infection, because of the 100% elimination rate of N. gonorrhoeae from the urethra, cervix and pharynx obtained in a recent study.

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.

Money, sex, and drugs: a case study to teach the genetics of antibiotic resistance

The goal of the work reported here was to help students expand their understanding of antibiotic resistance, the Central Dogma, and evolution. We developed a unit entitled "Ciprofloxacin Resistance in Neisseria gonorrhoeae," which was constructed according to the principles of scientific teaching by a team of graduate students, science faculty, and instructors. A variety of activities and assessments were used, including a case study, short lectures, and group problem-solving. Implementation of "Ciprofloxacin Resistance in Neisseria gonorrhoeae" in a college freshman seminar suggests these materials are useful in increasing understanding of complex biological topics and improving problem-solving abilities.

Sexually transmitted diseases in the USA: temporal trends

This paper reviews the temporal trends in sexually transmitted diseases (STDs) and discusses the factors affecting the epidemiology of bacterial STDs.

Neisseria gonorrhoeae isolates with reduced susceptibility to cefixime and ceftriaxone: association with genetic polymorphisms in penA, mtrR, porB1b, and ponA

The recent emergence and transmission of Neisseria gonorrhoeae isolates with reduced susceptibility to expanded-spectrum cephalosporins such as cefixime and ceftriaxone have been reported. The aim of this study was to determine the correlation of different polymorphisms in the penA, mtrR, porB1b (penB), and ponA genes of N. gonorrhoeae with reduced susceptibility to cefixime and ceftriaxone. Eighteen gonococcal isolates with reduced cefixime and ceftriaxone susceptibility (Cef(i)) and two susceptible isolates were characterized using serovar determination, antibiograms, N. gonorrhoeae multiantigen sequence typing (NG-MAST), and sequencing of penA, mtrR, porB1b, and ponA alleles. For the Cef(i) isolates (n = 18), the MICs of cefixime and ceftriaxone ranged between 0.032 to 0.38 mug/ml and 0.064 to 0.125 mug/ml, respectively. These isolates were assigned five different serovars and six divergent NG-MAST sequence types. Eleven isolates (61%) with higher MICs of cefixime and ceftriaxone contained a nearly identical penA mosaic allele and previously described polymorphisms in mtrR (a single nucleotide [A] deletion in the promoter), penB (mutations in porB1b encoding loop 3 of PorB1b), and ponA (ponA1 polymorphism). The remaining seven Cef(i) isolates (39%), which had somewhat lower MICs of cefixime and ceftriaxone, contained an aspartic acid insertion (Asp-345a) in PBP 2 in conjunction with alterations of 4 to 10 amino acid residues in the C-terminal region of the transpeptidase domain of penA. In conclusion, an unambiguous association between penA mosaic alleles, in conjunction with genetic polymorphisms in mtrR, porB1b, and ponA, and greater reduced susceptibility to cefixime and ceftriaxone was identified.

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.

Amino acid substitutions in mosaic penicillin-binding protein 2 associated with reduced susceptibility to cefixime in clinical isolates of Neisseria gonorrhoeae

The molecular mechanisms of reduced susceptibility to cefixime in clinical isolates of Neisseria gonorrhoeae, particularly amino acid substitutions in mosaic penicillin-binding protein 2 (PBP2), were examined. The complete sequence of ponA, penA, and por genes, encoding, respectively, PBP1, PBP2, and porin, were determined for 58 strains isolated in 2002 from Japan. Replacement of leucine 421 by proline in PBP1 and the mosaic-like structure of PBP2 were detected in 48 strains (82.8%) and 28 strains (48.3%), respectively. The presence of mosaic PBP2 was the main cause of the elevated cefixime MIC (4- to 64-fold). In order to identify the mutations responsible for the reduced susceptibility to cefixime in isolates with mosaic PBP2, penA genes with various mutations were transferred to a susceptible strain by genetic transformation. The susceptibility of partial recombinants and site-directed mutants revealed that the replacement of glycine 545 by serine (G545S) was the primary mutation, which led to a two- to fourfold increase in resistance to cephems. Replacement of isoleucine 312 by methionine (I312M) and valine 316 by threonine (V316T), in the presence of the G545S mutation, reduced susceptibility to cefixime, ceftibuten, and cefpodoxime by an additional fourfold. Therefore, three mutations (G545S, I312M, and V316T) in mosaic PBP2 were identified as the amino acid substitutions responsible for reduced susceptibility to cefixime in N. gonorrhoeae.

RpoH mediates the expression of some, but not all, genes induced in Neisseria gonorrhoeae adherent to epithelial cells

Neisseria gonorrhoeae (gonococcus [GC]), is highly adapted to the human host, the only known reservoir for gonococcal infection. However, since it is sexually transmitted, infection of a new host likely requires a regulatory response on the part of the gonococcus to respond to this significant change in environment. We previously showed that adherence of gonococci to epithelial cells results in changes of gene expression in the bacteria that presumably prepare them for subsequent steps in the infection process. Expression of the heat shock sigma factor gene, rpoH, was shown to be important for the invasion step, as gonococci depleted for rpoH were reduced in their ability to invade epithelial cells. Here, we show that of the genes induced in adherent gonococci, two are part of the gonococcal RpoH regulon. When RpoH is depleted, expression of these genes is no longer induced by host cell contact, indicating that RpoH is mediating the host cell induction response of these genes. One RpoH-dependent gene, NGO0376, is shown to be important for invasion of epithelial cells, consistent with earlier observations that RpoH is necessary for this step of infection. Two genes, NGO1684 and NGO0340, while greatly induced by host cell contact, were found to be RpoH independent, indicating that more than one regulator is involved in the response to host cell contact. Furthermore, NGO0340, but not NGO1684, was shown to be important for both adherence and invasion of epithelial cells, suggesting a complex regulatory network in the response of gonococci to contact with host cells.

Activity of gemifloxacin tested against Neisseria gonorrhoeae isolates including antimicrobial-resistant phenotypes

The antigonococcal potency of gemifloxacin and 5 reference comparator antimicrobials was determined for a selected collection of gonococcal isolates. The 250 Neisseria gonorrhoeae strains were inclusive of (1) 50 historic strains from Japan with elevated fluoroquinolone minimal inhibitory concentration values (QRNG) and (2) 200 contemporary strains from clinical specimens in 2004 (176 from 6 sentinel sites in the United States and 24 bacteremic isolates from the SENTRY Antimicrobial Surveillance Program). The rank order of potency of the tested antimicrobials for the entire collection was: ceftriaxone (MIC(90) = 0.06 microg/mL) > gemifloxacin (1 microg/mL) > tetracycline (2 microg/mL) > ciprofloxacin = levofloxacin = penicillin (4 microg/mL). The activity of gemifloxacin was not affected by penicillinase production; however, its activity was decreased for penicillin-resistant strains. Cross-resistance between gemifloxacin and the older fluoroquinolones was present, and the gemifloxacin MIC90 value was higher for the ciprofloxacin-resistant strains compared with the ciprofloxacin-susceptible strains (2 versus 0.016 mug/mL, respectively). More than 20.0% of the recent clinical strains were resistant to penicillin, tetracycline, and ciprofloxacin with >30.0% of gonococci resistant to ciprofloxacin in Washington State and Hawaii. The historic QRNG strains from the Far East were predominantly of intermediate susceptibility (88.0%) to ciprofloxacin, with a gemifloxacin MIC90 value of only 0.25 microg/mL. The bacteremic gonococcal strains were exquisitely susceptible to the 3 quinolones tested (ciprofloxacin, levofloxacin, and gemifloxacin, MIC90 at < or = 0.03 microg/mL) and ceftriaxone (MIC90 = 0.06 microg/mL). In summary, the potency of gemifloxacin was competitive and positioned between that of ceftriaxone and older quinolones or penicillin or tetracycline, irrespective of the gonococcal resistance phenotype. Gemifloxacin should be considered for further development as a therapeutic option to treat uncomplicated infections due to emerging strains resistant to penicillins, tetracycline, and some older fluoroquinolones.