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Volume 20, Number 7—July 2014
Dispatch

Neisseria gonorrhoeae Strain with Reduced Susceptibilities to Extended-Spectrum Cephalosporins

Author affiliations: San Francisco Department of Public Health, San Francisco, California, USA (D. Nguyen, S. Gose, L. Castro, K. Chung, K. Bernstein, M. Pandori); California Department of Public Health, Richmond, California, USA (M. Samuel, H. Bauer)

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Abstract

The spread of Neisseria gonorrhoeae strains with reduced susceptibility to extended-spectrum cephalosporins is an increasing public health threat. Using Etest and multiantigen sequence typing, we detected sequence type 1407, which is associated with reduced susceptibilities to extended-spectrum cephalosporins, in 4 major populated regions in California, USA, in 2012.

Neisseria gonorrhoeae infections are the second most common sexually transmitted infection in the United States (1). Gonorrhea typically presents as urethritis in men and cervicitis in women but when left untreated can result in severe sequelae, such as infertility (2,3). Gonorrhea infections continue to be a public health problem worldwide, and control efforts have been complicated because of the ability of the organism to develop resistance to all first-line antimicrobial drugs used in treatment, including penicillins, tetracyclines, and fluoroquinolones.

Treatment failures and isolates with reduced susceptibilities to extended-spectrum cephalosporins (ESCs) have been detected in Asia (4,5), Canada (6), Europe (7,8), and South Africa (9). In the United States, ESCs are currently the foundation of treatment recommendations. However, the increasing prevalence of isolates with reduced susceptibility to ESCs has led to dual treatment with ceftriaxone plus azithromycin or doxycycline. This combination is the only recommended treatment regimen of the US Centers for Disease Control and Prevention (CDC) (10).

N. gonorrhoeae isolates with reduced susceptibility to ESCs have been linked to altered penicillin-binding protein, which is encoded by the penA gene. Molecular and genomic epidemiologic studies have been used to describe N. gonorrhoeae antimicrobial drug resistance to ESCs in much of the world. In the United States, isolates with reduced susceptibility to cefixime have been associated with a specific strain of N. gonorrhoeae (11). However, little is known about the molecular epidemiology of strains with reduced susceptibilities to ceftriaxone, the current recommended ESC. In this study, we conducted surveillance for genotypic and phenotypic diversity of N. gonorrhoeae strain diversity in California during January 2012–September 2013.

The Study

Urethral gonococcal isolates were obtained from men with urethral infections during the CDC-sponsored Gonococcal Isolate Surveillance Project (GISP) at sites in Los Angeles, Orange, San Diego and San Francisco Counties in California. Duplicates of all GISP isolates from these sites were analyzed at the San Francisco Department of Public Health Laboratory by using Etest and at the GISP regional laboratory by using agar dilution. Antimicrobial drug susceptibility testing was performed by using Etest (bioMérieux, Marcy l’Etoile, France) as part of the California rapid response project to enhance surveillance efforts aimed at detecting treatment failures and containing the spread of isolates that require increased MICs of third-generation cephalosporins.

A total of 718 isolates were tested for susceptibility to ceftriaxone, cefixime, and azithromycin by Etest. In brief, frozen isolates were thawed in a biosafety cabinet at room temperature, inoculated onto a chocolate II agar plate containing 1% Iso VitaleX (Becton Dickinson, Franklin Lakes, NJ, USA), and incubated at 37°C with in an atmosphere of 5% CO2 for 20–25 h. A sterile swab was then used to collect colonies on the plate and suspend them in typticase soy broth containing 15% glycerol to give a turbidity of 0.5–1 MacFarland units. Using another sterile swab, we plated out the liquid culture onto 3 chocolate II agar plates in three 90° turnings. We then placed an Etest strip in the center of each plate by using a manual applicator. After incubation for 20–25 h at 37°C in an atmosphere of 5% CO2, the plates were examined, and MICs of each drug were recorded according to the manufacturer’s instructions.

Molecular epidemiologic typing was performed by using N. gonorrhoeae multiantigen sequence typing (NG-MAST) on all isolates. NG-MAST was performed as described (12) and allele numbers of porB and tbpB genes and sequence types (STs) were assigned by using the NG-MAST website (http://www.ng-mast.net).

Of 718 urethral isolates that were sequence typed, 258 STs were identified that had 192 porB alleles and 60 tbpB alleles. Eighty-three STs were present among ≥2 isolates in the collection, and the remaining 175 STs were unique. The 5 most prevalent STs identified were ST2400 (55, 7.7%), ST2992 (46, 6.4%), ST3307 (45, 6.3%), ST1407 (38, 5.3%), and ST7268 25, 3.5%). These STs constituted 29% of all isolates obtained. ST1407, the fourth most prevalent ST in this study, has been associated with ESC treatment failures in Europe and Canada. In California, this ST and closely related STs were associated with reduced susceptibility to ESCs, but these STs remained susceptible to azithromycin.

Because of the high discriminatory power of NG-MAST, which assigns STs on the basis of single basepair differences, we sought to assess diversity on the basis of genogroups. Genogroups were defined as having identical tbpB alleles and ≥99% DNA sequence similarity within porB alleles as defined by NG-MAST (13). The 718 urethral isolates sequence typed for this study formed 56 genogroups (≥2 isolates) and 92 ungrouped isolates with unique STs. The 5 most common genogroups were G2992 (n = 70, 9.7%), G2400 (n = 59, 8.2%), G3307 (n = 52, 7.2%), G1407 (n = 45, 6.3%) and G3935 (n = 31, 4.3%) (Table 1, Appendix).

Most isolates in our study required low MICs (≤0.023 μg/mL) for ceftriaxone and cefixime. Proportions of low, intermediate, and high MICs required by isolates in the 5 most prevalent genogroups are shown in Table 2. The G2400 and G1407 isolates were the only genogroups to require predominantly intermediate MICs of ceftriaxone and cefixime (0.032−0.094 μg/mL). G1407 comprised 91% (10/11) of isolates that required a high MIC of ceftriaxone and 93% (14/15) of isolates that required a high MIC of cefixime. Overall, 99.7% (716/718) of isolates required an MIC of azithromycin ≤1.5 μg/mL, of which 88% (629/716) required an MIC of azithromycin ≤0.380 μg/mL. Only 2 isolates required an MIC of azithromycin ≥2.0 μg/mL (2.0 μg/mL and 3.0 μ /mL).

Seventeen isolates that had reduced susceptibility phenotypes for ESCs (ceftriaxone MIC ≥0.125 μg/mL and cefixime MIC ≥0.125 μ /mL) were subjected to penA sequencing to determine the presence an altered penA gene. Sequencing was performed as described (14). Sequencing of penA genes showed that 100% (17/17) had the mosaic penA XXXIV allele. Genetic characteristics of isolates that required high MICs of ESCs are shown in Table 3. The tbpB 110 allele was found in 100% (17/17) of the isolates that required high MICs of ESCs Cs, and 94% (16/17) were G1407.

Conclusions

Genotypic surveillance of N. gonorrhoeae has been performed in the United States and elsewhere, but little is known about the genetic diversity of strains circulating in the United States, according to CDC recommended treatment guidelines. We sought to perform phenotypic and genotypic surveillance of isolates from major population centers in California in 2012. ST1407, a widespread strain linked to ESC treatment failures, was found in all 4 counties in California and was the fourth most prevalent ST overall.

In this study, ST1407 was associated with reduced susceptibility to ceftriaxone and cefixime. These data show that ST1407 is well established in California and are consistent with results from Asia (4,5), Canada (15), Europe (8), and the United States (11). All G1407 isolates that required increased MICs of ceftriaxone or cefixime had penA allele XXXIV. Among the 718 isolates in this study, none had reduced susceptibility to azithromycin and an ESC. The relatively high prevalence of this strain type, combined with the evolutionary capacity of N. gonorrhoeae to evade antimicrobial drug pressure, may eventually lead to circumstances where even dual therapy is not sufficient.

Mr Nuygen is a training fellow at the Association of Public Health Laboratories/CDC Emerging Infectious Diseases Laboratory at the San Francisco Public Health Laboratory, San Francisco, California. His research interests are the epidemiology and control of antimicrobial drug resistance.

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Acknowledgments

We thank the public health laboratories and clinics of Orange, Los Angeles, San Diego, and San Francisco Counties in California for participating in this study.

This study was supported in part by an appointment to the Emerging Infectious Diseases Laboratory Fellowship Program administered by the Association of Public Health Laboratories and funded by CDC.

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References

  1. Centers for Disease Control and Prevention (CDC). CDC Grand Rounds: the growing threat of multidrug-resistant gonorrhea. MMWR Morb Mortal Wkly Rep. 2013;62:1036 .PubMedGoogle Scholar
  2. Al-Fouzan  A, Al-Mutairi  N. Overview of incidence of sexually transmitted diseases in Kuwait. Clin Dermatol. 2004;22:50912 . DOIPubMedGoogle Scholar
  3. Ndowa  F, Lusti-Narasimhan  M. The threat of untreatable gonorrhoea: implications and consequences for reproductive and sexual morbidity. Reprod Health Matters. 2012;20:7682 . DOIPubMedGoogle Scholar
  4. Olsen  B, Pham  TL, Golparian  D, Johansson  E, Tran  HK, Unemo  M. Antimicrobial susceptibility and genetic characteristics of Neisseria gonorrhoeae isolates from Vietnam, 2011. BMC Infect Dis. 2013;13:40. DOIPubMedGoogle Scholar
  5. Tanaka  M, Nakayama  H, Huruya  K, Konomi  I, Irie  S, Kanayama  A, Analysis of mutations within multiple genes associated with resistance in a clinical isolate of Neisseria gonorrhoeae with reduced ceftriaxone susceptibility that shows a multidrug-resistant phenotype. Int J Antimicrob Agents. 2006;27:206 . Epub 2005 Nov 28. DOIPubMedGoogle Scholar
  6. Allen  VG, Mitterni  L, Seah  C, Rebbapragada  A, Martin  IE, Lee  C, Neisseria gonorrhoeae treatment failure and susceptibility to cefixime in Toronto, Canada. JAMA. 2013;309:16370. DOIPubMedGoogle Scholar
  7. Unemo  M, Golparian  D, Syversen  G, Vestrheim  DF, Moi  H. Two cases of verified clinical failures using internationally recommended first-line cefixime for gonorrhoea treatment, Norway, 2010. Euro Surveill. 2010;15:19721 .PubMedGoogle Scholar
  8. Ison  CA, Town  K, Obi  C, Chisholm  S, Hughes  G, Livermore  DM, ; GRASP collaborative group. Decreased susceptibility to cephalosporins among gonococci: data from the Gonococcal Resistance to Antimicrobials Surveillance Programme (GRASP) in England and Wales, 2007–2011. Lancet Infect Dis. 2013;13:7628. Epub 2013 Jun 11. DOIPubMedGoogle Scholar
  9. Lewis  DA, Sriruttan  C, Müller  EE, Golparian  D, Gumede  L, Fick  D, Phenotypic and genetic characterization of the first two cases of extended-spectrum-cephalosporin-resistant Neisseria gonorrhoeae infection in South Africa and association with cefixime treatment failure. J Antimicrob Chemother. 2013;68:126770 . Epub 2013 Feb 14. DOIPubMedGoogle Scholar
  10. Maldonado  NG, Takhar  SS. Update on emerging infections: news from the Centers for Disease Control and Prevention. Update to the CDC’s Sexually Transmitted Diseases Treatment Guidelines, 2010: oral cephalosporins no longer a recommended treatment for gonococcal infections. Ann Emerg Med. 2013;61:915. DOIPubMedGoogle Scholar
  11. Grad  YH, Kirkcaldy  RD, Trees  D, Dordel  J, Harris  SR, Goldstein  E, Genomic epidemiology of Neisseria gonorrhoeae with reduced susceptibility to cefixime in the USA: a retrospective observational study. Lancet Infect Dis. 2014;14:2206. DOIPubMedGoogle Scholar
  12. Martin  IM, Ison  CA, Aanensen  DM, Fenton  KA, Spratt  BG. Rapid sequence-based identification of gonococcal transmission clusters in a large metropolitan area. J Infect Dis. 2004;189:1497505. DOIPubMedGoogle Scholar
  13. Chisholm  SA, Unemo  M, Quaye  N, Johansson  E, Cole  MJ, Ison  CA, Molecular epidemiological typing within the European Gonococcal Antimicrobial Resistance Surveillance Programme reveals predominance of a multidrug-resistant clone. Euro Surveill. 2013;18:20358 .PubMedGoogle Scholar
  14. Pandori  M, Barry  PM, Wu  A, Ren  A, Whittington  WL, Liska  S, Mosaic penicillin-binding protein 2 in Neisseria gonorrhoeae isolates collected in 2008 in San Francisco, California. Antimicrob Agents Chemother. 2009;53:40324. Epub 2009 Jun 22. DOIPubMedGoogle Scholar
  15. Martin  I, Sawatzky  P, Allen  V, Hoang  L, Lefebvre  B, Mina  N, Emergence and characterization of Neisseria gonorrhoeae isolates with decreased susceptibilities to ceftriaxone and cefixime in Canada: 2001–2010. Sex Transm Dis. 2012;39:31623. DOIPubMedGoogle Scholar

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Tables

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Cite This Article

DOI: 10.3201/eid2007.131396

Table of Contents – Volume 20, Number 7—July 2014

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Duylinh Nguyen, San Francisco Public Health Laboratories, San Francisco Department of Public Health, 101 Grove St, San Francisco, CA 94102, USA

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Page created: June 17, 2014
Page updated: June 17, 2014
Page reviewed: June 17, 2014
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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