Neisseria gonorrhoeae

Neisseria gonorrhoeae is a Gram-negative diplococcus that causes gonorrhoea. The primary sites of infection are the mucous membranes of the urethra, endocervix, rectum, pharynx and conjunctiva. Transmission is by direct inoculation of infected secretions from one mucous membrane to another.

In men, urethral infection commonly causes discharge; over 90% of urethral infections in men are symptomatic. Rectal infection in homosexual men is usually asymptomatic, but may cause anal discharge or perianal discomfort. In women, endocervical infection is often asymptomatic (up to 50%). Pharyngeal infection is usually asymptomatic.

Spread from the urethra or endocervix may occur, resulting in epididymitis and prostatitis in men and PID and perihepatitis in women. Haematogenous dissemination occurs uncommonly, resulting in skin lesions, arthralgia and arthritis. Conjunctivitis in adults can occur if the organism is transmitted from the genitalia to the hands and then to the eyes. Concurrent urethritis is typically present.

Neisseria gonorrhoeae may be transmitted from a pregnant woman to her newborn during vaginal delivery. This usually results in conjunctivitis, but disseminated disease with bacteraemia, arthritis or meningitis can occur.

Non-culture methods, such as PCR, are being increasingly used on numbers of gonococcal infections in patient samples. The diagnosis has been made easier, as N. gonorrhoeae DNA can be detected in urine samples for males with urethritis, or females with cervicitis. Currently, there are no routine molecular tests available for sensitivity testing.

Culture for N. gonorrhoeae is routinely performed on all genital swabs, eye swabs from infants under four weeks old, and first-catch urines. Rectal and pharyngeal swabs can be examined for neisseria if the clinical details indicate that an STI is suspected. Culture has the benefit that it allows for susceptibility testing of the isolate involved.

Screening for coincident STIs should routinely be performed in patients with, or at risk of, gonorrhoea. Depending on the incubation period of the particular STI, repeat testing over time may be needed.

In 2017, resistance to the penicillins in Australia was 26%, with the exception of the remote Northern Territory, where resistance was less than 5%. Nationally, 27% of gonococci tested had some sort of resistance to the quinolones (for example, ciprofloxacin). Intramuscular ceftriaxone plus oral azithromycin is the empiric treatment of choice for the treatment of suspected gonorrhoeae. Ceftriaxone will also eradicate unsuspected pharyngeal or anorectal infection or carriage. Ceftriaxone is also used for treating gonococcal infections during pregnancy and in children. Systemic therapy is required for gonococcal conjunctivitis. If the infecting strain is known to be ciprofloxacin susceptible, ciprofloxacin can be used in non-pregnant adults. Cultures should be taken for resistance testing on any gonococcal infection, but especially those that relapse or fail treatment.

There is a high rate of co-infection with Chlamydia trachomatis and empirical treatment for this should also be given.

Patients should be advised to avoid unprotected sexual intercourse until they and their partner(s) have completed treatment.

Infections due to N. gonorrhoeae are notified by the testing laboratory to the Public Health department in each state or territory.

Notification of a sexually transmitted infection (STI) in children aged one year or over, or younger, depending upon the circumstances, should raise the suspicion of sexual abuse. The treating physician should be aware of the requirements of each state and make a clinical notification of his or her concerns to the Department of Child Safety.