Question 36#

Which one of the following is true regarding linezolid?

A. Active against both MRSA and VRE (Vancomycin-Resistant Enterococcus)

Correct Answer A: 

Linezolid:

Linezolid is a type of oxazolidonone antibiotic which has been introduced in recent years. It inhibits bacterial protein synthesis by stopping formation of the 70s initiation complex and is bacteriostatic nature.

Spectrum, highly active against Gram positive organisms including:

• MRSA (Methicillin-resistant Staphylococcus aureus)
• VRE (Vancomycin-resistant enterococcus)
• GISA (Glycopeptide Intermediate Staphylococcus aureus)

Adverse effects:

• Thrombocytopenia (reversible on stopping)
• Monoamine oxidase inhibitor: avoid tyramine containing foods

Question 37#

A 43-year-old Asian man presents with headache and neck stiffness. CT brain is normal and a lumbar puncture is performed with the following results:

• Serum glucose 4.7 mmol/l

Lumbar puncture reveals:

• Opening pressure 15 cmCSF
• Appearance Cloudy
• Glucose 3.3 mmol/l
• Protein 0.7 g/l
• White cells 100 / mm³ (70% lymphocytes)

What is the most likely diagnosis?

A. Bacterial meningitis

Correct Answer B: The CSF lymphocytosis combined with a glucose greater than half the serum level points towards a viral meningitis. TB meningitis is associated with a low CSF glucose.

Meningitis: CSF analysis:

The table below summarizes the characteristic cerebrospinal fluid (CSF) findings in meningitis:

The Ziehl-Neelsen stain is only 20% sensitive in the detection of tuberculous meningitis and therefore PCR is sometimes used (sensitivity = 75%).

*mumps is unusual in being associated with a low glucose level in a proportion of cases. A low glucose may also be seen in herpes encephalitis:

• Serum glucose 4.9 mmol/l

Lumbar puncture reveals:

• Opening pressure 14 cmCSF
• Appearance Cloudy
• Glucose 1.7 mmol/l
• Protein 1.9 g/l
• White cells 900 / mm³ (90% polymorphs)

Question 38#

A 23-year-old woman comes for review. She has had recurrent genital warts for the past 4 years which have failed to respond to topical podophyllum. On one occasion she had cryotherapy but will not have it again due to local discomfort. On examination she has a large number of fleshy genital warts around her introitus.

What is the most appropriate next step in treatment?

A. Topical glutaraldehyde

Correct Answer C: 

Genital warts:

Genital warts (also known as condylomata accuminata) are a common cause of attendance at genitourinary clinics. They are caused by the many varieties of the human papilloma virus HPV, especially types 6 & 11. It is now well established that HPV (primarily types 16,18 & 33) predisposes to cervical cancer.

Features:

• Small (2 - 5 mm) fleshy protuberances which are slightly pigmented
• May bleed or itch

Management:

• Topical podophyllum or cryotherapy are commonly used as first-line treatments depending on the location and type of lesion. Multiple, non-keratinized warts are generally best treated with topical agents whereas solitary, keratinized warts respond better to cryotherapy
• Imiquimod is a topical cream which is generally used second line
• Genital warts are often resistant to treatment and recurrence is common although the majority of anogenital infections with HPV clear without intervention within 1-2 years 

Question 39#

A 30-year-old man presents to the genito-urinary medicine clinic. He has been handed a slip from an ex-girlfriend stating she has tested positive for Chlamydia. He last slept with her 2 months ago. He has no symptoms of note, in particular no dysuria or discharge.

What is the most appropriate management?

A. Reassure symptoms would have presented by now

Correct Answer C: Treatment is given on the basis of exposure to infection rather than proven infection.

Chlamydia:
Chlamydia is the most prevalent sexually transmitted infection in the UK and is caused by Chlamydia trachomatis, an obligate intracellular pathogen. Approximately 1 in 10 young women in the UK have Chlamydia. The incubation period is around 7-21 days, although it should be remembered a large asymptomatic.

Features:

• Asymptomatic in around 70% of women and 50% of men
• Women: cervicitis (discharge, bleeding), dysuria
• Men: urethral discharge, dysuria 

Potential complications:

• Epididymitis
• Pelvic inflammatory disease
• Endometritis
• Increased incidence of ectopic pregnancies
• Infertility
• Reactive arthritis
• Perihepatitis (Fitz-Hugh-Curtis syndrome)

Investigation:

• Traditional cell culture is no longer widely used
• Nuclear acid amplification tests (NAATs) are now rapidly emerging as the investigation of choice
• Urine (first void urine sample), vulvovaginal swab or cervical swab may be tested using the NAAT technique

Screening:

• In England the National Chlamydia Screening Programme is open to all men and women aged 15- 24 years
• The 2009 SIGN guidelines support this approach, suggesting screening all sexually active patients aged 15-24 years
• Relies heavily on opportunistic testing

Management:

• Doxycycline (7 day course) or azithromycin (single dose). The 2009 SIGN guidelines suggest azithromycin should be used first-line due to potentially poor compliance with a 7 day course of doxycycline
• If pregnant then erythromycin or amoxicillin may be used. The SIGN guidelines suggest considering azithromycin 'following discussion of the balance of benefits and risks with the patient'
• Patients diagnosed with Chlamydia should be offered a choice of provider for initial partner notification - either trained practice nurses with support from GUM, or referral to GUM
• For men with symptomatic infection all partners from the four weeks prior to the onset of symptoms should be contacted
• For women and asymptomatic men all partners from the last six months or the most recent sexual partner should be contacted
• Contacts of confirmed Chlamydia cases should be offered treatment prior to the results of their investigations being known (treat then test)

Question 40#

A 33-year-old man is admitted due to profuse diarrhoea. He has a history of HIV infection and Cryptosporidium diarrhoea is suspected.

What investigation is most likely to confirm the diagnosis?

A. Blood cultures

Correct Answer D: Cryptosporidium cysts turn red following acid-fast staining. Molecular methods are currently used mainly as a research tool.

Possible causes:

• Cryptosporidium + other protozoa (most common)
• Cytomegalovirus
• Mycobacterium avium intracellulare
• Giardia

Cryptosporidium is the most common infective cause of diarrhoea in HIV patients. It is an intracellular protozoa and has an incubation period of 7 days. Presentation is very variable, ranging from mild to severe diarrhoea. A modified Ziehl-Neelsen stain (acid-fast stain) of the stool may reveal the characteristic red cysts of Cryptosporidium. Treatment is difficult, with the mainstay of management being supportive therapy*

Mycobacterium avium intracellulare is an atypical mycobacteria seen with the CD4 count is below 50. Typical features include fever, sweats, abdominal pain and diarrhoea. There may be hepatomegaly and deranged LFTs. Diagnosis is made by blood cultures and bone marrow examination. Management is with rifabutin, ethambutol and clarithromycin.

*Nitazoxanide is licensed in the US for immunocompetent patients.