Differentials
Lymphogranuloma venereum
SIGNS / SYMPTOMS
More invasive serotype causing genital ulcer and/or inguinal lymphadenopathy, or proctitis with rectal infection.
INVESTIGATIONS
Identification of Chlamydia trachomatis genovars/serovars L1, L2, or L3 (collectively termed the 'LGV biovar') from the swab of a genital ulcer or aspiration of a bubo is definitive diagnosis.
Gonorrhoea infection
SIGNS / SYMPTOMS
Signs and symptoms of cervical or male urethral discharge are generally more pronounced with gonorrhoea.
INVESTIGATIONS
Nucleic acid amplification test (NAAT) for gonorrhoea alone is positive. May see gram-negative intracellular diplococci on Gram stain of infected specimens.
Bacterial vaginosis
SIGNS / SYMPTOMS
Vaginal discharge tends to be thin and have a fishy odour.
INVESTIGATIONS
Clue cells will be present on microscopic examination.
Vaginal pH >4.5.
A KOH (potassium hydroxide) whiff test of vaginal discharge will liberate a fishy odour.
Molecular tests for bacterial vaginosis-associated bacteria are available.
Vaginal candidiasis
SIGNS / SYMPTOMS
Vaginal discharge may be thick and white in the vaginal vault. External genital symptoms such as itching and burning are more likely.
INVESTIGATIONS
Hyphae or budding yeast present on microscopic examination of KOH preparation of vaginal secretions.
Trichomonas vaginitis
SIGNS / SYMPTOMS
Men tend to be asymptomatic but can be carriers. Women classically have a thin, greyish, frothy vaginal discharge in the vaginal vault. Discharge tends to be worse straight after menses. The cervix, rarely, may be inflamed and have a strawberry appearance.
INVESTIGATIONS
Mobile trichomonads present on microscopic examination in many cases.
Nucleic acid amplification tests (NAATs) are available.
Mycoplasma infection
SIGNS / SYMPTOMS
Caused by the organism Mycoplasma genitalium. Frequently asymptomatic; however, can cause cervicitis and PID in women, and urethritis in men. It can also infect the rectum and pharynx.
INVESTIGATIONS
A nucleic acid amplification test (NAAT) test for M genitalium is US Food and Drug Administration approved, available but is not yet in widespread use.
Pelvic inflammatory disease (PID)
SIGNS / SYMPTOMS
A wide range of bacterial infections, including chlamydia, can ascend the female reproductive tract, causing pelvic or abdominal pain, fevers, nausea/vomiting, dyspareunia, and intermenstrual bleeding. Diagnostic criteria for PID include cervical motion tenderness and/or adnexal tenderness. The diagnosis is presumed when chlamydial infection and cervical motion tenderness coexist.
INVESTIGATIONS
There are no differentiating tests. PID is a clinical diagnosis.
Persistent or refractory urethritis in men
SIGNS / SYMPTOMS
Patients with persistent urethritis symptoms who did not comply with the treatment regimen or who were re-exposed to an untreated sex partner can be retreated with the initial antibiotic regimen. True treatment failures after treatment for genital tract chlamydia are rare. Re-infection is more likely. The most common cause of recurrent or persistent urethritis is Mycoplasma genitalium, especially following treatment with doxycycline. Less common causes include Ureaplasma urealyticum and Trichomonas vaginalis.
INVESTIGATIONS
Nucleic acid amplification test (NAAT) for M genitalium are available. Polymerase chain reaction (PCR) can be used to detect U urealyticum DNA from a urine sample or a vaginal swab. In the US, some laboratories have performed the necessary Clinical Laboratory Improvement Amendments (CLIA) of the Centers for Disease Control and Prevention validations and can perform nucleic acid amplification tests (NAATs) for T vaginalis detection. As well as NAATs for T vaginalis, rapid, point-of-care tests are available for diagnosis from vaginal sampling.
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