Neisseria gonorrhoeae 2007

Transcription

1 Magnus Unemo Date: Page 1 of 6 Neisseria gonorrhoeae 2007 Annual report regarding serological characterisation and antibiotic susceptibility of Swedish Neisseria gonorrhoeae strains In 2007, 487 Swedish N. gonorrhoeae (GC) isolates from 404 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 Clinical Microbiology, Örebro University Hospital, Örebro, Sweden or to the Division of Clinical Bacteriology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden. In total, 406 different GC strains from 396 patients were identified. Thus, two patients were infected with two different strains on the same occasion and eight were infected with two divergent strains on different occasions during the year. In addition, 107 GC isolates, lacking identity of the patients and/or inquire for complete characterisation, were submitted during the year. Of the 487 characterised GC isolates, 288 were cultured from urethra or cervix, 66 from pharynx, 52 from rectum, three from other locations (blood, eye, or abdomen), and 78 specimens were unspecified. All the 406 different GC strains are presented in Table I. In 2007, 642 gonorrhoea cases were notified, in accordance with the Swedish Communicable Diseases Act, SMI, Solna, Sweden. Notably, the number of notified gonorrhoea cases in Sweden is decreasing. For comparison, 677 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 31% and Thailand was the predominant country for exposure. Of all the gonorrhoea cases (n=642), 60% were heterosexually acquired, 31% were homosexually acquired, and in 9%, the transmission route was not described or other route (personal communication, Inga Velicko, epidemiologist, SMI). The GC isolates from 404 gonorrhoea cases, which were submitted for complete characterisation, represented 63% of the notified cases. Age and gender In 392 of the gonorrhoea cases (n=404), the age of the patient was depicted. The mean age of all cases was 32 years and the median age was 30 years, i.e. similar as in In 402 of the cases (68 women and 334 men, gender ratio 1:4.9), the gender of the patient was described or possible to determine. The ranges of the ages were 16 to 67 years and 15 to 70 years for the men and women, respectively. The mean age of the women was 29 years and the median age Address: National Reference Laboratory for Pathogenic Neisseria Department of Clinical Microbiology Örebro University Hospital SE Örebro Sweden Telephone: Fax: magnus.unemo@orebroll.se

2 Page 2 of 6 24 years (in 2006, 28 years and 24 years, respectively). The mean age of the men was 33 years and the median age 31 years (in 2006, 32 years and 29 years, respectively). Serological characterisation Of the different GC strains (n=406), 50 strains were assigned serogroup WI (PorB1a) and 356 strains were determined as serogroup WII/III (PorB1b). In Table I, the serogroup distribution, serovar distribution and specimens for all the different strains submitted to the National Reference Laboratory for Pathogenic Neisseria, Örebro or to the laboratory in Huddinge are described. Accordingly, in the annual report for 2007 these results are compiled. The Reference Laboratory in Örebro has during 2006 evaluated the Pharmacia (Ph) monoclonal antibodies (mabs; PhadeBact GC Serovar Test, Bactus AB) (1) and from the beginning of 2007, the Ph mabs are used for serovar determination. However, on request also the Genetic Systems mabs 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). At the Reference Laboratory, the susceptibility to ciprofloxacin was also determined with Nalidixic acid discs (30 µg) on IsoSensitest Agar supplemented with 5% defibrinated horse blood and 20 mg/l β-nicotinamide adenine dinucleotide (NAD). β- lactamase production was analysed using Nitrocefin discs. Of the 406 GC strains, 121 (30%) were β-lactamase producing, i.e. PPNG. A high level of decreased susceptibility and resistance to traditional antibiotics used for treatment of gonorrhoea, i.e. ampicillin and ciprofloxacin, was identified. All the ciprofloxacin resistant strains were also identified with Nalidixic acid discs. All the 406 strains were fully susceptible to spectinomycin and ceftriaxone. However, six strains (1.5%) showed a significantly increased MIC (0.125 mg/l) of ceftriaxone. Twenty-three strains (5.7%) showed a decreased susceptibility and five strains (1.2%) were resistant to azithromycin. 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 2001 to 2007 is summarised.

3 Swedish N. gonorrhoeae strains submitted for characterisation in 2007 were: Page 3 of 6 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. mainly (88%) determined as serogroup WII/III (PorB1b). predominated by the Ph serovars Bropyst (n=109), Arst (n=43), and Bpyust (n=38), Table I. β-lactamase producing in 30% (PPNG strains) of the cases, Table II. to a higher level, i.e. 6.9%, showing a decreased susceptibility or resistance to azithromycin (in 2006, 5.1%), Table II. to a very high level showing a decreased susceptibility or resistance to ciprofloxacin (70%), Table II. Overall, ceftriaxone, spectinomycin, cefotaxime, cefixime or in some occasional cases, such as with 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 (from a microbiological point of view). Notable in 2006 As previously described in the annual reports for 2005 and 2006, an increased awareness of prolyliminopeptidase (PIP)-negative GC strains has to be emphasised. These strains lack the PIP enzyme that previously has been considered as almost universally present in GC. The PIP-negative GC strains may be difficult to identify using commercial biochemical kits such as API-NH, RapID NH, Neisseria PET, etc (3, 4). In addition, 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 (4). This really 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. For effective treatment of gonorrhoea it is crucial to locally, regionally and nationally monitor the antibiotic susceptibility of the bacteria. In Sweden, it is highly recommended that all GC isolates are analyzed regarding their antibiotic susceptibility. 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 (5-7). In special epidemiological situations and/or for research purposes, the Reference Laboratory performs genetic characterisation of GC strains. Pulsed-field gel electrophoresis (PFGE) (3-5, 7-9) and/or sequencing of the porb gene (1, 3-12) and the tbpb gene (1, 4-9) are effective genetic methods for epidemiological characterisation of GC strains. The epidemiological

4 Page 4 of 6 and/or scientifical questions asked in relation to each project have to guide the use of appropriate method(s). In the future, the Reference Laboratory will hopefully afford to genetically characterise all Swedish GC isolates. Örebro Magnus Unemo, Per Olcén, Hans Fredlund, Paula Mölling, and co-workers at the National Reference Laboratory for Pathogenic Neisseria (an external body of the Swedish Institute for Infectious Disease Control [SMI]), Department of Clinical Microbiology, Örebro University Hospital, Örebro, Sweden. Betina Colucci, Eva-Lena Ericson, Bengt Wretlind, and co-workers at the Division of Clinical Bacteriology, Department of Laboratory Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden. 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; In press. 2. The Swedish Reference Group for Antibiotics (SRGA) and its subcommittee on Methodology (SRGA-M) ( 3. Fjeldsøe-Nielsen H, Unemo M, Fredlund H, Hjort SV, Berthelsen LM, Palmer HM, and Friis- Möller A. Phenotypic and genotypic characterisation of prolyliminopeptidase-negative Neisseria gonorrhoeae isolates in Denmark. Eur J Clin Microbiol Infect Dis 2005;24: 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: 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. 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 porbbased 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:

5 Page 5 of 6 Table I. Serogroup distribution, serovar distribution (Pharmacia`s panel of monoclonal antibodies) and specimens for different N. gonorrhoeae strains (n=406) 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 Arost WII/III Bropyst Bpyust Bpyvut Bropt Bropst Brpyust Bpyut Bropyt Bopyst Bopyt Byvut Brps Brpyut Brpyst Bpyst Bopt Bpyvt Broyus Brpys Other serovars b Total a Other specimens were blood (n=1), eye (n=1) and abdomen (n=1). b Serovars that were identified in less than three cases fall (Ar, Ars, Arsv, Ast, Bopst, Bopvt, Bps, Bpst, Bpys, Bpyt, Bpyvust, Brop, Broput, Bropvt, Bropys, Bropyut, Bropyust, Bropyvst, Brpoyst, Brpust, Brpyvut, Brys, Bryu, Bryus, Bryut, Bryvut, Byut, Byvus och Byvust).

6 Page 6 of 6 Table II. Percentages of Swedish N. gonorrhoeae strains comprising β-lactamase production, decreased susceptibility or resistance in (n=141) 2002 (n=120) 2003 (n=130) 2004 (n=149) 2005 (n=497) # 2006 (n=352) # 2007 (n=406) # β-lactamase production Ampicillin *, ** MIC > > <1 Cefixime > > Ceftriaxone > Azithromycin > > Ciprofloxacin > <1 <1 > Spectinomycin > # From 2005, all strains submitted to the National Reference Laboratory for Pathogenic Neisseria, Örebro, Sweden and to the Karolinska University Hospital Huddinge, Stockholm, Sweden are presented. * Minimum inhibitory concentration (MIC) in mg/l. ** PPNG strains are not included; 2001 (n=89), 2002 (n=73), 2003 (n=102), 2004 (n=110), 2005 (n=384), 2006 (n=248), and 2007 (n=285). Report sent to: SMI, att: Annika Linde, Margareta Löfdahl, Anders Blaxhult, Inga Velicko ECDC, att: Zsuzsanna Jakab, Johan Giesecke, Karl Ekdahl, Marita van der Laar Swedish National Institute of Public Health, att: Gunilla Rådö International Collaboration Group on Gonococci (ICG), att: John Tapsall European Surveillance of Sexually Transmitted Infections (ESSTI), att: Catherine Ison Centers for Disease Control and Prevention (CDC), att: Ronald Ballard