Increasing incidence of microbiologically confirmed gonorrhoea in northern North Yorkshire

Dr Nigel C. Weightman, Consultant Medical Microbiologist, Friarage Hospital, Northallerton, North Yorkshire, DL6 1JG.

Introduction
In England and Wales, the number of gonorrhoea diagnoses has been rising since 1994, with substantial annual increases being observed over recent years.1 We investigated whether this trend had been observed locally, using only microbiologically confirmed cases of gonorrhoea.

Methods
The Microbiology Department provides services for a population of 120,000 in one area of northern North Yorkshire, serving the local Hospital, General Practitioners, and two Genito-Urinary Medicine (GUM) clinics. Departmental statistics for new patients with isolates of Neisseria gonorrhoeae were analysed for the period January 1998 to June 2002. From July 2001, most isolates were sent to the Gonococcus Reference Unit (GRU) at the Public Health Laboratory, Bristol for typing and detailed antimicrobial susceptibility testing. In addition, information on new patient attendees since January 2001 at the two local GUM clinics was obtained.

Results
There was a substantial increase in the number of isolates of N. gonorrhoeae between 1998 and 2002, most marked from June 2001 (Figures 1 and 2). There were increasing numbers of new attendees at the GUM clinics, but with marked month-to-month variability (Figure 3). Age and sex distribution of patients from GUM clinics and General Practitioners are shown in Table 1. Auxotype distribution of available strains from June 2001 to May 2002 is shown in Figure 4. All 46 of these strains were serogrouped, 5 being serogroup W1 and 41 serogroup W11/111. Beta-lactamase production and GRU-confirmed antimicrobial susceptibility data are shown in Table 2.

Figure 1. Isolates of N. gonorrhoeae, Northallerton Laboratory, January 1998 to June 2002

Figure 2. Isolates of N. gonorrhoeae, Northallerton Laboratory, January 2000 to June 2002

Figure 3. New attendees at local GUM clinics, January 2001 to June 2002, and trend line

Figure 4. Auxotypes of 40 available isolates of N. gonorrhoeae Northallerton Laboratory, June 2001 to May 2002 
*NR = prototrophic

Discussion
The number of microbiologically confirmed local cases of gonorrhoea rose suddenly and markedly in mid 2001. This is in contrast to England and Wales data (from KC60 returns), which show that gonorrhoea increased noticeably from 1998.1 The majority of cases were from the two GUM clinics, but over the last 30 months, 14.5% were from General Practitioners, a proportion rather higher than studies from cities and larger towns.2 The number of new attendees at the GUM clinics has shown a gradual upward trend over the last eighteen months but not a sudden increase to coincide with the rise in new cases of gonorrhoea in mid 2001. The number of reproductive tract specimens for microbiological investigations from general practitioners has remained stable since January 2000. Neither antimicrobial susceptibility patterns nor auxotyping has shown a single predominant type. Review of contact histories by GUM clinic staff revealed a wide geographical spread of probable source contacts, further suggesting that the increase is not due to either a single strain or a single or small group of infected source individuals. The reason for the sudden upsurge in 2001 of cases of microbiologically confirmed gonorrhoea locally is not clear. There was a sexual health campaign in the area in summer 2001, including recommendations that symptomatic individuals promptly present to local GUM clinics, which may have contributed to the increase in cases presenting to the GUM clinics. As the number of cases of gonorrhoea rises nationally, unprotected sex within the UK will have an increased chance of acquiring gonorrhoea and this may also have contributed to the increase observed.Resistance to penicillin and beta-lactamase production is in line with national figures, the former being 7% locally and 9% nationally, and the latter 4% locally and 5% nationally.2 Resistance to ciprofloxacin is higher than that seen nationally (4% locally, 1.8% nationally) but tetracycline resistance (including intermediate resistance) was much lower than the national figure (17% locally, 38% nationally).2

Table 1. Age and sex distribution of new patients yielding N. gonorrhoeae, Northallerton Laboratory, January 2001 to June 2002

Source Number Age (years) Male: Female
    maximum minimum mean  
GUM clinic A 21 41 16 24 16:5
GUM clinic B 37 31 17 21 37:0
General practice 10 34 16 22 5:5
Hospital inpatient 1 27 27 27 0:1

Table 2. Antimicrobial susceptibility data for 46 isolates of N. gonorrhoeae, Northallerton Laboratory, June 2001 to May 2002

Antimicrobial Sensitive* Intermediate* Resistant
  number % number % number %
benzylpenicillin 20 43 23 50 3** 7
ceftriaxone 46 100 0 0 0 0
ciprofloxacin 44 96 0 0 2 4
spectinomycin 46 100 0 0 0 0
tetracycline 38 83 6 13 2 4

*Gonococcus Reference Laboratory breakpoints
**2 strains produced beta-lactamase

Conclusion
Even in non-city areas, gonorrhoea can rise markedly and investigation into the potential causes should be instigated locally. This can be assisted by typing and antimicrobial susceptibility data from the Microbiology Laboratory, and analysis of potential source contacts by the GUM clinic. Despite this, the reasons for the increase in incidence may remain obscure.

References

  1. CDSC. Diagnoses of gonorrhoea reach ten-year high. Communicable Disease Report CDR Weekly 2001; 11: (30). Available at: www.phls.co.uk/publications/cdr/PDFfiles/2001/cdr3001.pdf
  2. CDSC. The gonococcal resistance to antimicrobials surveillance programme, annual report, year 2000 collection. Public Health Laboratory Service. Available at: www.phls.org.uk/topics_az/hiv_and_sti/sti-gonorrhoea/epidemiology/grasp_report.pdf

 

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