Behçet's disease (BD) is a chronic, relapsing multisystem vasculitis with predominant involvement of the oral and genital mucosa. It has a worldwide distribution, but the prevalence is highest in Central Asia and the Far East (along the ancient 'Silk Route'). Genetic, environmental, immunological and haemostatic factors play a role in the aetiopathogenesis. The International Study Group for BD proposed criteria for the diagnosis of this condition, the essential feature being recurrent oral ulceration. Genital ulcers and skin manifestations are common, while ocular changes are the most important cause of morbidity. Almost any organ in the body can be involved, and systemic involvement may portend a poorer prognosis. There is no pathognomonic test for BD and the diagnosis is made on clinical findings. Treatment of BD would require multidisciplinary cooperation, and early referral to an ophthalmologist is advisable to prevent ocular morbidity. Topical and systemic agents (colchicine, dapsone and thalidomide) are useful in controlling exacerbation of the oral and genital ulcers. Severe disease may require immunosuppressive agents and, more recently, biological agents have been used successfully. It tends to follow an unpredictable course, and the eventual prognosis depends on the systemic involvement.

Pharyngeal infection with Neisseria gonorrhoeae (NG) in heterosexual men is thought to be of low prevalence and the value of routinely testing this group of patients is uncertain. We present two cases of NG, isolated only in the pharynx, in asymptomatic heterosexual male contacts. The presence of pharyngeal NG was found irrespective of direct oropharyngeal sexual exposure.

Sir: In this journal, last June 2005, Doctors Brook and Bell 1 expressed reservations that we in Chester appear to have abandoned swabs for gonorrhoea in asymptomatic patients. They were concerned about the issue of false positive tests for gonorrhoea using the APTIMA COMBO 2 transcription mediated amplification test (TMA) in areas of low prevalence. We have now looked at results for the last 12 months and our findings reassure us that not only is APTIMA COMBO 2 testing as good as culture, it in fact out-performs it. Of the 82 cases of gonorrhoea diagnosed between October 2004 and October 2005, there were eight cases where either urethra in men or cervix in women was negative on culture. In five of these cases, however, either culture was positive on another site, or microscopy was positive (Table 1). There were three cases in female patients where microscopy and culture were negative, but the TMA test was positive, indicating that these patients would have been missed if we had not been using APTIMA COMBO 2 TMA test.Of the three cases diagnosed only on TMA we had data indicating that their partner had gonorrhoea allowing us to say with reasonable certainty that these were true positives.This short review allows us to categorically state that the APTIMA COMBO 2 test never missed a single case that had been diagnosed by culture. Our findings are consistent with a view that extra positives by APTIMA COMBO 2 over culture could be labelled 'false positives' in clinical trials and be fed into erroneous calculation of positive predictive values.The specificity of the APTIMA COMBO 2 test is hardly in doubt, based on these results, and we therefore feel confident in continuing our policy of screening genuinely asymptomatic men or women who attend the clinic for a check up with either a first catch urine or if the woman prefers, a self-taken vaginal swab. This is a novel way of maintaining easy access and filtering easy to screen asymptomatic patients into nurse-led parallel clinics.References 1 Brook G, Bell C. Asymptomatic urethritis; the case for a considered view -reply letter. Int J STD AIDS 2005;16:456-7

The aim of this study was to assess if patient characteristics could influence the sensitivity of enzyme immunoassay (EIA) testing used for chlamydia screening. Our cohort consisted of 56 patients who were known polymerase chain reaction-positive for chlamydia, but with variable EIA results. Characteristics analysed included those already known to influence the EIA (menstruation, pregnancy, difficult examination) and those suspected from clinical observation (including presence of symptoms or signs, coexistent gonorrhoea, duration from last sexual exposure). An unexpected finding was that significantly more cases of bacterial vaginosis were found in those chlamydia EIA-negative compared to those with positive results. We postulate that an enzyme produced in bacterial vaginosis, proline aminopeptidase, may cause destruction of the chlamydial cell wall, therefore affecting the EIA adversely. Further research is needed to explore this hypothesis.

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