Neisseria gonorrhoeae 2009

Transcription

1 Magnus Unemo Date: Page 1 of 7 Neisseria gonorrhoeae 2009 Annual report regarding serological characterisation and antibiotic susceptibility of Swedish Neisseria gonorrhoeae strains In 2009, 427 Swedish N. gonorrhoeae (GC) isolates from 387 clinical gonorrhoea cases were submitted for complete characterisation to the National Reference Laboratory for Pathogenic Neisseria (an external body of the Swedish Institute for Infectious Disease Control [SMI]), Department of Laboratory Medicine, Clinical Microbiology, Örebro University Hospital, Örebro, to the Division of Clinical Bacteriology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Stockholm, or to the Clinical Microbiology Malmoe, Skåne University Hospital, Sweden. In total, 384 different GC strains from 383 patients were identified. Thus, one patient was infected with two different strains on the same occasion and four were infected on two different occasions (same strain) during the year. Of the 427 characterised GC isolates, 280 were cultured from urethra or cervix, 52 from rectum, 36 from pharynx, two from other locations (eye [n=1] and joint [n=1]), and 57 specimens were unspecified. All the 329 different GC strains, which also were serologically characterised, are presented in Table I. In 2009, 611 (incidence: 6.5 cases per inhabitants) gonorrhoea cases were notified, in accordance with the Swedish Communicable Diseases Act, SMI, Solna, Sweden. Notably, the number of notified gonorrhoea cases in Sweden has decreased. For comparison, 721 (incidence: 7.8) cases were notified in Most of the cases were identified in the three largest counties of Sweden, which comprise the cities Stockholm, Gothenburg, and Malmoe, respectively. The proportion of patients infected abroad was 35% and Thailand was the predominant country for exposure. Of all the gonorrhoea cases (n=612), 68% were heterosexually acquired, 28% were homosexually acquired, and in 4%, the transmission route was not described or other route (personal communication, Inga Velicko, epidemiologist, SMI). The different GC strains (n=384) from 387 gonorrhoea cases, which were submitted for complete characterisation, represented 63% of the notified cases. Serological characterisation Of the different GC strains (n=329), 84 (26%) strains were assigned serogroup WI (PorB1a) and 245 (74%) strains were determined as serogroup WII/III (PorB1b). In Table I, the serogroup distribution, serovar distribution (PhadeBact GC Serovar Test, Bactus AB; 1) and specimens for all the different strains submitted to the National Reference Laboratory for Address: National Reference Laboratory for Pathogenic Neisseria Department of Laboratory Medicine, Clinical Microbiology Örebro University Hospital SE Örebro Sweden Telephone: Fax: magnus.unemo@orebroll.se

2 Page 2 of 7 Pathogenic Neisseria, Örebro or to the laboratory in Huddinge are described. On request also the Genetic Systems monoclonal antibodies can be used. Antibiotic susceptibility The susceptibility of all isolates to ampicillin, cefixime, ceftriaxone, azithromycin, ciprofloxacin, and spectinomycin was analyzed using the Etest method (AB Biodisk, Solna, Sweden) on GC Medium Base agar (supplemented with 1% haemoglobin and 1% IsoVitaleX). Breakpoints for susceptibility (S), intermediate susceptibility (I), and resistance have been determined by the Reference Laboratory and Swedish Reference Group on Antibiotics (2). β-lactamase production was analysed using Nitrocefin discs. Of the 384 GC strains, 170 (44%) were β-lactamase producing, i.e. PPNG. A high level of intermediate susceptibility and resistance to traditional antibiotics used for treatment of gonorrhoea, i.e. ampicillin and ciprofloxacin, was identified. All the 384 strains were fully susceptible to ceftriaxone and spectinomycin. Nineteen strains (5%) had a reduced susceptibility/resistance to cefixime. Thirty-one strains (8%) displayed an intermediate susceptibility and 23 strains (6%) were resistant to azithromycin. However, adequate correlates between laboratory and clinical parameters for these antimicrobials are lacking. Accordingly, more knowledge as well as an increased awareness when these two antimicrobials are used for treatment are crucial. No obvious correlation between antibiotic susceptibility and any individual serovar was possible to identify, however, many of the serovars were only represented by occasional strains. In Table II, the antibiotic susceptibility of Swedish GC strains from 2003 to 2009 is summarised. Swedish N. gonorrhoeae strains submitted for characterisation in 2009 were: representing 63% of the notified gonorrhoea cases. Most of the gonorrhoea cases were identified in the three largest counties of Sweden, which comprise the cities Stockholm, Gothenburg, and Malmoe, respectively. mostly (74%) determined as serogroup WII/III (PorB1b). predominated by the serovars Bropyst (n=86), Arst (n=71), and Bpyut (n=53), Table I. β-lactamase producing in 44% (PPNG strains) of the cases, which is a substantially higher figure than previous years Table II. to a relatively high level displaying intermediate susceptibility or resistance to azithromycin (14%) and cefixime (5%), Tabell II. to a very high level showing an intermediate susceptibility or resistance to ciprofloxacin (76%), Table II. Overall, ceftriaxone, cefixime, spectinomycin, or in some rare cases, such as after performed in vitro susceptibility testing and with

3 Page 3 of 7 concurrent Chlamydia trachomatis infection, azithromycin is the recommended first choice of antibiotic for the treatment if the results from the antibiotic susceptibility testing is pending. Important is to monitor the intermediate susceptibility/resistance to cefixime and to have an increased awareness when cefixime is used for treatment, especially for pharyngeal gonorrhoea. Notable in 2009 As previously described in the annual reports from the Reference Laboratory, an increased awareness of prolyliminopeptidase (PIP)-negative GC strains that are difficult to identify using commercial biochemical kits (3) has to be emphasised. A more or less global transmission of one PIP-negative GC strain and its genetically highly related subtypes has been described but also other PIP-negative strains are circulating in many countries (3). This stresses the need of using additional methods, e.g. antigenic/serological methods such as coagglutination (PorB protein) or DNA/RNA-based methods, for species confirmation. However, a recent study examining the prevalence and characteristics of PIP-negative GC isolates in Sweden during showed that these isolates have been rare in Sweden. Only 15 (1.2%) of 1230 examined GC strains were PIP-negative, and all these were identified during (4). For effective treatment of gonorrhoea it is crucial to locally, nationally, and internationally monitor the GC antibiotic resistance (AMR), which is a major concern globally (5). In Sweden, it is recommended that all GC isolates are analyzed regarding their antibiotic susceptibility. In 2009, for enhanced quality assurance of the resistance testing the recently comprehensively characterised and designated 2008 WHO N. gonorrhoeae reference strains (6), intended for global quality assurance and control of GC AMR, have been implemented. Furthermore, it is crucial to increase the knowledge regarding the genetic basis for resistance to most antibiotics as well as to develop genetic assays for antimicrobial resistance screening for GC (7-11). An increased number of Swedish laboratories show interest to use commercial nucleic acid amplification tests (NAATs) for routine diagnosis of gonorrhoea. This is mainly not recommended due to the lack of AMR testing as well as the suboptimal specificity, causing very low positive predictive values, of mainly all GC NAATs. Accordingly, the choice of an effective GC NAAT and the need of confirmatory testing using other method, i.e. culture or NAAT detecting other genetic target, are crucial to stress. The Reference Laboratory uses highly sensitive and specific single- and dual-target GC NAATs for confirmation of samples positive in the commercial NAATs (12-14). In special epidemiological situations and/or for research purposes, the Reference Laboratory performs genetic characterisation of GC strains. Pulsed-field gel electrophoresis (PFGE) (3, 7, 9, 15-17) and/or sequencing of the porb gene (1, 3, 4, 6-9, 15-18) and the tbpb gene (1, 3, 4, 6-9, 16) are effective genetic methods for epidemiological characterisation of GC strains. The epidemiological and/or scientifical questions asked in relation to each project have to guide the use of appropriate method(s).

4 Page 4 of 7 Örebro Magnus Unemo, Per Olcén, Emma Johansson, Paula Mölling, Hans Fredlund, and coworkers at the National Reference Laboratory for Pathogenic Neisseria (an external body of the Swedish Institute for Infectious Disease Control [SMI]), Department of Laboratory Medicine, Section Clinical Microbiology, Örebro University Hospital, Örebro, Sweden. Anna-Karin Ohlsson, Eva-Lena Ericson, Division of Clinical Bacteriology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden. Berit Hammas, Clinical Microbiology Malmoe, Skåne University Hospital.

5 Page 5 of 7 References 1. Olsen B, Hadad R, Fredlund H, and Unemo M. The Neisseria gonorrhoeae population in Sweden during 2005 phenotypes, genotypes and antibiotic resistance. APMIS 2008;116: The Swedish Reference Group for Antibiotics (SRGA) and its subcommittee on Methodology (SRGA- M) ( 3. Unemo M, Palmer HM, Blackmore T, Herrera G, Fredlund H, Limnios A, Nguyen N, and Tapsall J. Global transmission of prolyliminopeptidase (PIP)-negative Neisseria gonorrhoeae strains - implications for changes in diagnostic strategies? Sex Transm Infect 2007;83: Johansson E, Fredlund H, Unemo M. Prevalence, phenotypic and genetic characteristics of prolyliminopeptidase-negative Neisseria gonorrhoeae isolates in Sweden during APMIS 2009;117: Tapsall JW, Ndowa F, Lewis DA, Unemo M. Meeting the public health challenge of multidrug- and extensively drug-resistant Neisseria gonorrhoeae. Expert Rev Anti Infect Ther 2009;7: Unemo M, Fasth O, Fredlund H, Limnios A, Tapsall J. Phenotypic and genetic characterization of the 2008 WHO Neisseria gonorrhoeae reference strain panel intended for global quality assurance and quality control of gonococcal antimicrobial resistance surveillance for public health purposes. J Antimicrob Chemother. 2009;63: Lundbäck D, Fredlund H, Berglund T, Wretlind B, and Unemo M. Molecular epidemiology of Neisseria gonorrhoeae identification of the first presumed Swedish transmission chain of an azithromycin resistant strain. APMIS 2006;114: Lindberg R, Fredlund H, Nicholas R, and Unemo M. Neisseria gonorrhoeae isolates with reduced susceptibility to cefixime and ceftriaxone: association with genetic polymorphisms in pena, mtrr, porb1b, and pona. Antimicrob Agents Chemother 2007;51: Unemo M, Sjöstrand A, Akhras M, Gharizadeh B, Lindbäck E, Pourmand N, Wretlind B, and Fredlund H. Molecular characterization of Neisseria gonorrhoeae identifies transmission and resistance of one ciprofloxacin-resistant strain. APMIS 2007;115: Unemo M, Olcén P, Fredlund H, Thulin S. Real-time PCR and subsequent pyrosequencing for screening of pena mosaic alleles and prediction of reduced susceptibility to expanded-spectrum cephalosporins in Neisseria gonorrhoeae. APMIS 2008;116: Zhao S, Duncan M, Tomberg J, Davies C, Unemo M, Nicholas RA. Genetics of chromosomally mediated intermediate resistance to ceftriaxone and cefixime in Neisseria gonorrhoeae. Antimicrob Agents Chemother 2009;53: Hjelmevoll SO, Olsen ME, Sollid JU, Haaheim H, Unemo M, Skogen V. A fast real-time polymerase chain reaction method for sensitive and specific detection of the Neisseria gonorrhoeae pora pseudogene. J Mol Diagn 2006;8: Hjelmevoll SO, Olsen ME, Sollid JU, Haaheim H, Melby KK, Moi H, Unemo M, Skogen V. Clinical validation of a real-time polymerase chain reaction detection of Neisseria gonorrheae pora pseudogene versus culture techniques. Sex Transm Dis 2008;35: Goire N, Nissen MD, LeCornec GM, Sloots TP, Whiley DM. A duplex Neisseria gonorrhoeae realtime polymerase chain reaction assay targeting the gonococcal pora pseudogene and multicopy opa genes. Diagn Microbiol Infect Dis 2008;61: Unemo M. Genotypic and phenotypic characterisation of Neisseria gonorrhoeae. Linköping University Medical Dissertations no. 828, Fredlund H, Falk L, Jurstrand M, and Unemo M. Molecular genetic methods for diagnosis and characterisation of Chlamydia trachomatis and Neisseria gonorrhoeae: impact on epidemiological surveillance and interventions. APMIS 2004;112: Unemo M, Olcèn P, Albert J, and Fredlund H. Comparison of serologic and genetic porb-based typing of Neisseria gonorrhoeae: consequences for future characterization. J Clin Microbiol 2003;41: Unemo M, Olcén P, Jonasson J, and Fredlund H. Molecular typing of Neisseria gonorrhoeae by pyrosequencing of highly polymorphic segments of the porb gene. J Clin Microbiol 2004;42:

6 Page 6 of 7 Table I. Serogroup distribution, serovar distribution and specimens for different N. gonorrhoeae strains (n=329) submitted to the National Reference Laboratory for Pathogenic Neisseria, Örebro or to the Karolinska University Hospital Huddinge, Sweden in Serogroup Serovar Urethra Cervix Pharynx Unspecified or Rectum other specimens a Total WI Arst Ars Art 3 3 Ast WII/III Bropyst Bpyut Brpyust Bpyvut Bropst Bropt Bpyust Brpyut Broput Bropyust Other serovars b Total a Other specimens were eye (n=1) and joint (n=1). b Serovars that were identified in less than three cases fall (Ar, Arost, Arostv, Bopt, Bopyst, Bopvt, Bopyt, Bopyust, Bopyut, Bopyvt, Bos, Boyt, Bpyt, Bpyst, Brop, Brops, Bropyt, Bropyvst, Bropyvt, Brpyst, Brpyvust, Brpyvut, Bryu, Bryus, Bryut). Two serogroup WII/III (PorB1b) strains were not possible to type.

7 Page 7 of 7 Table II. Percentages of Swedish N. gonorrhoeae strains comprising β-lactamase production, intermediate susceptibility or resistance in (n=130) 2004 (n=149) 2005 (n=497) # 2006 (n=352) # 2007 (n=406) # 2008 (n=447) # 2009 (n=384) # β-lactamase production Ampicillin *, ** MIC > > <1 0 0 Cefixime > <1 0 0 <1 1 5 Ceftriaxone > <1 0 Azithromycin > >0.5 <1 0 < Ciprofloxacin > <1 <1 <1 <1 > Spectinomycin > # From 2005, all strains submitted to the National Reference Laboratory for Pathogenic Neisseria, Örebro and to the Karolinska University Hospital Huddinge, Stockholm, and from 2009 also submitted to Malmö University Hospital, Sweden are presented. * Minimum inhibitory concentration (MIC) in mg/l. ** PPNG strains are not included; 2003 (n=102), 2004 (n=110), 2005 (n=384), 2006 (n=248), 2007 (n=285), 2008 (n=320), and 2009 (n=214). *** For cefixime and azithromycin, new SIR breakpoints were introduced in 2009 and the results from previous years have been recalculated. Report sent to: Swedish Institute of Infectious Disease Control, att: Annika Linde, Margareta Löfdahl, Inga Velicko, Magnus Thore, Lars Engstrand Swedish National Institute of Public Health, att: Gunilla Rådö European Centre for Disease Prevention and Control (ECDC), att: Zsuzsanna Jakab, Johan Giesecke, Karl Ekdahl, Marita van der Laar Eastern European Sexual and Reproductive Health Network, att: Marius Domeika WHO Collaborating Centre for STD, Sydney, Australia, att: John Tapsall WHO Headquarter, Geneva, Switzerland, att: Francis Ndowa Sexually Transmitted Bacterial Reference Laboratory, HPA, London, UK, att: Catherine Ison