Based on: Nasoodi A, Lim LT, Al-Ani A, Dinsmore WW.
An eye on sexually transmitted diseases: sexually transmitted diseases and their ocular manifestations.
Int J STD AIDS 2008; 19: 222-6
Correct responses to the CPD Test Questions published in the April 2008 issue with explanatory Comment
With regard to infectious causes of keratitis, the following is true:
(a) Gonococcal keratitis is not serious and can usually resolve spontaneously.
FALSE
(b) Herpes simplex keratitis should normally be treated with oral steroids.
FALSE
(c) Syphilitic keratitis usually responds to conventional treatment.
FALSE
(d) Ptyriasis pubis can never cause keratitis directly.
TRUE
(e) Herpes simplex keratitis per se will stain purple with Rose Bengal stain.
FALSE
Comment: Gonococcal keratitis should be treated promptly to avoid corneal perforation and endophthalmitis. Herpes simplex keratitis should initially be treated with topical and oral aciclovir. Syphilitic keratitis does not respond to conventional treatment. Ptyriasis pubis never directly cause keratitis. Herpes simplex keratitis per se will never stain with Rose Bengal stain.
The following statements are true:
(a) Thayer-Martin medium can be used to aid the diagnosis of chlamydia
FALSE
(b) McCoy cell culture can aid in the diagnosis of chlamydia.
TRUE
(c) The diagnosis of herpetic dendritic ulcer is usually done clinically.
TRUE
(d) Microhaemagglutination is one method to detect Treponema pallidum.
TRUE
(e) The diagnosis of Ptyriasis palpebrarum can only be made under a microscope.
FALSE
Comment: Thayer-Martin medium is used to aid in the diagnosis of Neisseria gonorrhoeae. Ptyriasis palbebrarum can be diagnosed clinically as sometimes the causative organism or its eggs can be seen with the naked eye.
The following statements are true about sexually transmitted bacterial conjunctivitis:
(a) Gonococcal conjunctivitis is usually subacute in nature.
FALSE
(b) Chlamydial conjunctivitis is usually very acute with copious green discharge.
FALSE
(c) Chlamydial conjunctivitis is caused by Chlamydia trachomatis serotypes A-C.
FALSE
(d) As the conjunctivitis progresses, pseudomembrane can be seen in chlamydial infection.
FALSE
(e) Lymphadenopathy does occur in both chlamydial and gonococcal conjunctivitis.
TRUE
Comment: Gonococcal conjunctivitis is usually acute in nature, and that of chlamydia is usually subacute. Chlamydial conjunctivitis is cause by C. trachomatis serotypes D-K. Pseudomembrane is seen in gonococcal conjunctivitis.
With regards to the painful red eye caused by STD:
(a) This can be due to intense inflammation of conjunctiva.
FALSE
(b) Keratitis is a major cause of the pain in this context.
TRUE
(c) Chlamydial keratitis can usually result in perforation of the cornea if untreated.
FALSE
(d) Rose Bengal staining can aid in the diagnosis of gonococcal keratitis.
FALSE
(e) HSV Type 2 keratitis is more common than Type 1.
FALSE
Comment: Conjunctivitis per se does not usually cause pain. Keratitis is a major cause of painful eyes as the inflammation directly and indirectly stimulates the corneal nerves. It is the gonococcal keratitis that can result in corneal perforation if left untreated. Rose Bengal is used to stain devitalised epithelium at the edges of dendritic ulcers. HSV Type 1 is far commoner than the Type 2 in causing HSV keratitis.
With regards to treatment of ocular infection secondary to STDs:
(a) Trifluorothymidine 1% is more commonly used to treat HSV keratitis compared with aciclovir, due to its less toxic effect on the corneal epithelium.
FALSE
(b) Systemic oral aciclovir prophylaxis is normally given to patients with HSV keratitis.
FALSE
(c) One way of treating chlamydial conjunctivitis is by giving the patient oral azithromycin 1 g once daily for seven days.
FALSE
(d) Gonococcal conjunctivitis can be easily treated with ampicillin.
FALSE
(e) Mainstay treatment of syphilitic ocular manifestation is with penicillin
TRUE
Comment: Aciclovir is preferred over trifluorothymidine partly due to it being less toxic to corneal epithelial cells. Oral aciclovir prophylaxis is generally considered in patients with recurrent HSV keratitis. Chlamydial conjunctivitis can be treated with a single dose of azithromycin 1 g. There is no place for ampicillin in the treatment of gonococcal conjunctivitis.
