STDs were commonly known as venereal diseases : Veneris is the Latin genitive form of the name Venus , the Roman goddess of love. Social disease was another euphemism. Public health officials originally introduced the term sexually transmitted infection , which clinicians are increasingly using alongside the term sexually transmitted disease in order to distinguish it from the former. According to Ethiopian AIDS Resource Center FAQ - Are sexually transmitted infections (STIs) different from sexually transmitted diseases (STDs)? , "Sometimes the terms STI and STD are used interchangeably. This can be confusing and not always accurate, so it helps first to understand the difference between infection and disease. Infection simply means that a germ, virus , bacteria , or parasite that can cause disease or sickness if present inside a person's body. An infected person does not necessarily have any symptoms or signs that the virus or bacteria is actually hurting his or her body; they do not necessarily feel sick. A disease means that the infection is actually causing the infected person to feel sick, or to notice something is wrong. For this reason, the term STI which refers to infection with any germ that can cause an STD, even if the infected person has no symptoms is a much broader term than STD. " The distinction being made, however, is closer to that between a colonization and an infection , rather than between an infection and a disease . Specifically, the term STD refers only to infections that are causing symptoms . Because most of the time people do not know that they are infected with an STD until they start showing symptoms of disease , most people use the term STD, even though the term STI is also appropriate in many cases. Moreover, the term Sexually Transmissible Disease is sometimes used since it is less restrictive in consideration of other factors or means of transmission. For instance, meningitis is transmissible by means of sexual contact but is not labeled as an STI because sexual contact is not the primary vector for the pathogens that cause meningitis. This discrepancy is addressed by the probability of infection by means other than sexual contact . In general, an STI is an infection that has a negligible probability of transmission by means other than sexual contact, but has a realistic means of transmission by sexual contact (more sophisticated means blood transfusion , sharing of hypodermic needles are not taken into account). Thus, one may presume that, if a person is infected with an STI, e.g., chlamydia , gonorrhea , genital herpes , it was transmitted to him/her by means of sexual contact. The English language has short words for two of the most common: "pox" ( syphilis ) and "the clap" ( gonorrhea ).

Conflict of Interest:

None declared

Your recent major article by Harryman et al 1 assessed the performance of Aptima Combo 2 (AC2) confirmed by Aptima GC (AGC) versus culture and concluded that AC2 with AGC confirmation performed well at genital and extra-genital sites for detection of GC. Culture with transport swabs was found to perform poorly for asymptomatic men, symptomatic and asymptomatic women and at extra-genital sites. The authors conclude that consideration should be given into how best to optimise GC culture in settings where direct plating is not feasible.

We strongly agree with them and are pleased to find the accumulating evidence for the performance benefits of AC2 confirmed with AGC. They mentioned that studies by Moss et al and Lavelle et al concluded that AC2 GC positives were likely to be true positives based on culture and partner data, but point out that both studies confirmed their positives only by repeating the same assay. However we in our later study confirmed all GC positives by AC2 by retesting residual sample in the AGC assay 2.

In our study we looked retrospectively at laboratory dual testing data between August 2006 and April 2008 and reviewed case-notes of all patients with a positive result for GC (culture or AC2 confirmed by AGC ). Testing was at Macclesfield genitourinary medicine (GUM) clinic (3589 dual NAATS samples from 1930 females and 2470 dual NAATS sample from 1867 males) and in the corresponding community served by the 'Team Chlamydia' office of the National Chlamydia Screening Programme (1549 male and 7934 female samples). Of the total of 15, 542 tests performed only one was positive for GC by AC2 but unconfirmed by AGC. There was no culture positive but AC2 negative result in any of our patients tested by both methods. At the GUM clinic, 6 (19%) male cases and 4 (25%) female cases would have been missed if tested only by culture. Of the 6 males, 3 were positive at extra-genital sites (pharyngeal swabs) only. In the community 23 young females would have gone undiagnosed and untreated for GC infection if tested only for chlamydia infection.

The overall positivity for GC in the GUM clinic was 1.3%, the true prevalence being 0.9% (after excluding already diagnosed cases referred from the community and those presenting as contacts) and that in the community was 0.4%.

Culture alone must now be considered unfit for testing asymptomatic patients and inadequate to meet the challenge of detecting and managing the large number of cases that are to be found outside of GUM settings 3. Following the recent Guideline 4- that GC should always be treated with a two antibiotic combination - GC culture may retain its importance for survey and monitoring of changes in antibiotic-susceptibility patterns but becomes less essential as a test for every individual patient.

Moncado et al 5 evaluated 3 of the CDC approaches for confirming GC positive NAAT results and concluded that confirmatory testing was not warranted for genital specimens. With our results and those of Harryman et al and as more evidence accumulates confidence may grow that, for AC2 at least, confirmation is unnecessary.

REFERENCES

1. Harryman L, Scofield S, Macleod J, et al. Comparative performance of culture using swabs transported in Amies medium and the Aptima Combo2 nucleic acid amplification test in detection of Neisseria gonorrhoeae from genital and extra-genital sites: a retrospective study. Sex Transm Infect 2011; doi;10.1136/sextrans-2011-050075

2. Mahto M, Zia S, Ritchie D, et al. Diagnosis, management and prevalence estimation of gonorrhoea: influences of Aptima Combo 2 assay with alternative target confirmation. International Journal of STD & AIDS 2009;20:315-319

3. Skidmore S, Copley S, Cordwell D et al. Positive nucleic acid amplification tests for Neisseria gonorrhoeae in young people tested as part of the National Chlamydia Screening Programme. International Journal of STD & AIDS 2011; 22: 398-399

4. Bignell C, FitzGerald M. UK national guideline for the management of gonorrhoea in adults, 2011. International Journal of STD & AIDS 2011;22:541-547

5. Moncada J, Donegan E, Schachter J. Evaluation of CDC- Recommended approaches for confirmatory testing of positive Neisseria gonorrhoeae nucleic acid amplification test results. J Clin Microbiol 2008;46:1614- 1619.

Conflict of Interest:

None declared