A 14-year-old boy is brought by his mother with a fever, sore throat and malaise. On examination he has an exudative pharyngitis with cervical lymphadenopathy. You order laboratory testing including a monospot test, which is positive.
Which ONE of the following is correct regarding Epstein-Barr virus (EBV)?
Answer: C: EBV (human herpes virus 4) is the usual cause of infectious mononucleosis (IM). After the 1–2 month incubation period a variety of illnesses can occur: typical EBV presents with fever, exudative pharyngitis, lymphadenopathy, splenomegaly and lymphocytosis. There may be elevated transaminases but jaundice and hepatomegaly are usually seen only in older adults. Splenomegaly is common, and is palpable in 50% of patients, usually during week 2 of the illness; all patients with IM should be counselled to avoid contact sports and strenuous activity for 4 weeks following the onset of symptoms to avoid the complication of splenic rupture.
Diagnosis is usually based on clinical symptoms plus rapid-result screening tests such as the monospot test, which indicates the presence of heterophile antibodies; such antibodies are induced by the EBV infection but are not specific to EBV and may be present with other infections including cytomegalovirus and toxoplasmosis.
Treatment is supportive in most cases and only in rare cases where complications such as anaemia and thrombocytopenia occur are controversial therapies such as corticosteroids used. Most patients recover fully from EBV, but resolution of symptoms including fatigue may take months; since patients may shed the virus intermittently for months or years after their infection, and the source of a case of IM is rarely known, there are no restrictions on when a patient with IM may return to school or work.
References:
A 12-year-old boy is referred to the ED by his GP with symptoms of a lower respiratory tract infection.
Which ONE of the following would be LEAST likely to support a diagnosis of Mycoplasma pneumonia?
Answer: D: Mycoplasma pneumonia is a cause of atypical pneumonia, seen often in older children, young adults and the elderly. Clinical features include a low-grade fever, chills, a non-productive cough, sore throat and headache; the onset is often insidious and patients may present after 2–3 weeks of symptoms. The cough can last 4–6 weeks. The chest X-ray may be relatively normal or may show patchy infiltrates, hilar adenopathy and pleural effusions but rarely shows lobar consolidation. Diagnosis is via serology and fluorescent antibody testing. Now measured less commonly than in the past, cold agglutinins are elevated in 50–70% of patients with mycoplasma pneumonia. Treatment is with macrolides or tetracyclines (in children > 10 years). The differential diagnosis includes Chlamydia pneumoniae, Chlamydia psittaci (seen with exposure to birds), viral pneumonia, or legionella pneumonia.
Which ONE of the following is CORRECT regarding patients with HIV presenting with gastrointestinal symptoms?
Answer: B: Gastrointestinal manifestations of HIV are common. Oral thrush affects 80% of HIV patients; it is treated with nystatin, clotrimazole or in resistant cases fluconazole or amphotericin B. However, oesophagitis is typically seen in patients with CD4 counts < 100 cells/uL and can be due to CMV or HSV as well as Candida. Oral hairy leukoplakia is due to opportunistic infection by EBV; adherent white patches along the lateral borders of the tongue are seen; treatment is not required and the lesions often recur after treatment with aciclovir. Diarrhoea is very common and may be due to drugs, bacteria, parasites (Giardia, Cryptosporidium, Isospora), viruses (CMV, HSV, HIV) and fungi (Histoplasmosis capsulatum, Cryptococcus neoformans). Cryptosporidium typically causes profuse watery diarrhoea and is difficult to treat, requiring both antiretroviral therapy and antiparasitic agents. Proctitis is also relatively common, and is usually due to Neisseria, Chlamydia trachomatis, syphilis and HSV; it causes painful defecation, rectal discharge and tenesmus; treatment is of the causative agent.
Reference:
A 24-year-old woman presents with a 5-day history of mild lower abdominal pain. As part of her ED examination she is found to have cervicitis but no discharge or signs of pelvic inflammatory disease.
Which ONE of the following is INCORRECT regarding this patient?
Answer: C: Cervicitis is commonly due to Chlamydia trachomatis infection; in women, infection may be asymptomatic or be a cause of infertility; other presentations include symptoms and signs of pelvic inflammatory disease, dyspareunia and vaginal discharge or lower abdominal pain if symptoms have been longstanding. Men are usually symptomatic with urethritis and a watery discharge; infection may also cause epididymitis, orchitis, proctitis and prostatitis.
Diagnosis is via PCR on an endocervical swab or 10 mL urine (men). Treatment involves either 7 days of doxycycline 100 mg po, or a single dose of azithromycin 1 g po; the latter is useful where compliance may be poor. Due to the common co-infection of patients with Chlamydial infections, treatment for N. gonorrhoeae should be given at the same time, with ceftriaxone 125 mg IM; sexual contacts within the last 60 days should also be treated for both infections.
Complications of chlamydial infection include pelvic inflammatory disease, infertility and ectopic pregnancy. Chlamydia is a notifiable disease. Vaginal candida infections may produce cervicitis but there is a prominent white discharge present; treatment is with cotrimoxazole.
A 3-year-old unimmunised girl is brought to the ED by her parents with a 1-day history of a mild fever, with refusal to eat or drink today. On examination she appears unwell, is sitting up and has a very swollen neck. Her pharynx is red with a thick grey-white coating over the posterior pharyngeal wall and tonsils.
Which ONE of the following is CORRECT regarding this patient?
Answer: A: Unimmunised patients are at risk for a number of now ‘rare’ infections including diphtheria, caused by the gram-positive rod Corynebacterium diphtheria, which may be toxigenic or non-toxigenic. Cutaneous diphtheria is usually due to non-toxigenic strains and produces punched out ulcers; it is treated with penicillin. Respiratory disease is usually due to toxigenic strains; a 2–5-day incubation period is followed by a sore throat with the characteristic adherent pseudomembrane coating the pharynx; patients typically develop a ‘bull neck’ due to soft tissue oedema; airway compromise is a major concern mandating intubation. Bacterial toxin effects are responsible for the local necrosis causing the pseudomembrane; the toxin is spread via the circulation and causes the delayed extrapharyngeal effects of myocarditis, cranial nerve palsies and skeletal muscle paralysis. Diagnosis involves isolating C diphtheria on culture of nasal and throat swabs (Loeffler’s medium) or by fluorescent antibody testing; toxigenicity testing is also performed.
Management involves airway management, ventilation and critical care support; specific therapy involves early intravenous administration of antitoxin 20,000–150,000 units followed by penicillin to stop further toxin production. All patients should be nursed in isolated negative pressure rooms with staff wearing N95 masks plus gowns, gloves and eye protection. Contacts should have nose and throat swabs cultured, receive prompt erythromycin prophylaxis, and should be examined daily for 7 days for evidence of disease.
Click to expand