Answer

Comments to this month's Clinical Challenge

A A T Chuh, MRCP(UK), MRCP(Irel), DipDerm(Glasg), DipGUM(LAS)
Family Physician in Private Practice,
T S Au, MRCP(UK), FHKAM(Medicine), DipDerm(Lond), DipGUM(LAS)
Specialist in Dermatology and Venerology,Social Hygiene Clinic, Department of Health.

Correspondence to:
Dr A A T Chuh,
Shop B5, Ning Yeung Terrace, 78 Bonham Road, G/F, Hong Kong.

Comments:

There are many definitions of the term "sexually transmitted disease" (STD). Many infections such as molluscum contagiosum and salmonellosis are sexually transmissible, but sexual activity is not the most common route. Hepatitis A, B, C and D viruses can all be transmitted by sexual activity including oral-genital contact. Defining STD as "a disease for which sexual activity is a possible route of transmission" would necessarily include all such infections. Thus, for practical purposes, one may define STD as "a disease for which sexual activity is the commonest or most important route of transmission". Genital herpes, condyloma acuminata and genital infections caused by Chlamydia trachomatis serovars D-K, for example, can comfortably be categorised as STDs.

We might consider "venereal disease" (VD) and STD as synonyms. According to the Merriam-Webster Dictionary, "venereal" means "resulting from or contracted during sexual intercourse" and "involving the genital organs". As such we have to define what "intercourse" is, and remember that transmission can occur during sexual activity not necessarily amounting to intercourse. Moreover, the pathology of STDs is not necessarily limited to the genital organs. Acquired immunodeficiency syndrome, for example, can affect all body systems and organs. Thus STD is probably a more preferable term than VD as the former is more precise.

High-vaginal swabs are not the ideal specimens for the diagnosis of Neisseria gonorrhoeae infection. Cervical exudate and rectal swabs should be sent to look for Gram-negative intracellular diplococci in the smear. Cervical exudate, rectal and pharyngeal swabs should also be sent for gonococcal culture. When immediate inoculation onto a culture plate is not possible, the specimen should not be refrigerated and should be sent to the laboratory within 4-6 hours.

That gonorrhoea is an STD is obvious because:

1. It has a relatively short incubation period (significantly shorter than non-gonococcal and non-specific urethritis)^1,2, and therefore a reliable contact history is likely to be available;
   
   
2. As many as 80-90%¹ of infected males and 60-80% of infected females are symptomatic (therefore the sexual partner(s) are also likely to be symptomatic);
   
   
3. Symptoms, if present, are highly noticeable;¹ and
   
   
4. Successful treatment leads to prompt symptomatic remission (therefore re-infection after further contact is obvious).

Overgrowth of Gardnerella vaginalis, Mycoplasma hominis, Mobiluncus spp and anaerobic bacteria is seen in bacterial vaginosis (BV), also known as nonspecific vaginitis. G.vaginalis was found in 87.5% of women with BV and in 26.4% of women with healthy vaginal ecosystems.³ No specific strain of G.vaginalis is involved.³

The patient may have a malodorous fish-like vaginal discharge, especially after intercourse. Perineal irritation and pruritus vulvae can also be present. Examination may reveal whitish non-viscous vaginal discharge with no evidence of mucopurulent cervicitis and no "strawberry cervix". The vaginal pH is high (above 4.7). A high vaginal swab for smear will reveal mixed flora with decreased lactobacilli and few leukocytes. Characteristic clue cells (vaginal epithelial cells with indistinct margins due to adherent bacteria) may be seen. For definitive diagnosis one may use the Nugent criteria, a scoring system that standardises the interpretation of the Gram's smear.⁴ The treatment of BV is oral metronidazole.

BV is associated with douching,⁵ with new sexual partners and with a history of other STDs including human immunodeficiency virus infection.^6,7 Oral contraceptives seem to be protective.⁵ On the other hand, there exists no definite male counterpart for BV and treatment of the male partner with metronidazole has not been shown to be beneficial for the female. Thus the STD status of BV remains controversial.

Candida albicans is a normal commensal organism in the vagina. Overgrowth causes vulvovaginitis. Diabetes mellitus and broad-spectrum antibiotics are predisposing factors. Sexual transmission of candida in women appears to be of minor importance and treatment of the male partner does not prevent recurrence. On the other hand, symptomatic genital candidiasis in men often appears to be sexually transmitted.