Internal Medicine
Board Review

Educational Objective:

Recognize association between Trichomonas infection and HIV.

Key Point:

Trichomonas infection facilitates subsequent HIV infection acquisition by those patients.

Explanation:

A strong association exists between Trichomonas infection and HIV acquisition, although the relationship is not well understood. In one study, Trichomonas infection before HIV acquisition was prevalent in 11.3% of patients who became HIV positive compared with 4.5% of patients who were HIV negative. The odds ratio for acquiring HIV was 2.74 in patients infected with Trichomonas after adjusting for other variables. Because Trichomonas infection facilitates HIV acquisition, researchers have hypothesized that T. vaginalis control may help prevent the transmission of HIV.

References:

Eckert L, Lentz GM. Infections of the lower and upper genital tracts. Lentz GM, et al. Comprehensive Gynecology. 6th ed., 2012.

Schwebke JR. Trichomonas vaginalis. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed., 2009:3535-3538.

Van Der Pol B, Kwok C, Pierre-Louis B, et al. Trichomonas vaginalis infection and human immunodeficiency virus acquisition in African women. J Infect Dis. 2008;197:548-554.

Educational Objective:

Diagnose and treat crusted scabies.

Key Point:

Crusted scabies, also known as Norwegian scabies, is a massive infestation by Sarcoptes scabiei that can affect immunocompromised patients and is characterized by crusted and hyperkeratotic plaques. Treatment is typically ivermectin.

Explanation:

The patient has Norwegian scabies and the best treatment option is oral ivermectin.

This form of scabies is the result of a massive infestation by Sarcoptes scabiei of the hominis variety that generally occurs in immunosuppressed patients, including those with post-transplant, leukemia, HIV infection, human T-cell lymphotropic virus type 1 infection, leprosy, or diabetes. A parasitic infestation with Norwegian scabies is easily missed because its symptoms can mimic psoriasis. Norwegian scabies usually evolves into crusted and hyperkeratotic plaques or nodules that are more prominent in the limbs.

The diagnosis of crusted scabies is based on clinical suspicion and identification of mites, eggs, or feces in a skin scraping.

Although topical scabicides such as malathion, permethrin, or lindane can be effective, the treatment of choice is a systemic medication, typically multiple doses of oral ivermectin plus a topical agent such as permethrin cream 5%. Malathion is not given to infants due to its concern for neurologic toxicity.

References:

Crusted Scabies. Centers of Disease Control and Prevention.  

Katsambas K, Dessinioti C. Parasitic diseases of the skin. In: Kellerman RD, Bope ET. Conn’s Current Therapy. 2018:976-982.

Educational Objective:

Choose the most specific test for rheumatoid arthritis.

Key Point:

Antibodies to citrulinated peptides are the test of choice to diagnose rheumatoid arthritis. The results are as sensitive as a positive rheumatoid factor but much more specific.

Explanation:

ELISA assay for antibodies to a cyclic peptide containing citrulline (anti-CCP) has become widely commercially available over the last few years. Antibodies to citulinated peptides are as sensitive as a rheumatoid factor but are much more specific.

This assay has shown a specificity of 95% and sensitivity of 67% for the diagnosis of RA. Specificity of IgM RF is around 82% with a sensitivity of 73%.

CRP is important to follow disease activity, but is not useful in the diagnosis of disease. HLA DR alleles, particularly HLA DR4, may be potentially useful as it is associated with aggressive disease; however, it is not useful for diagnosis and is not commercially available.

The rheumatoid factor is positive in close to 80% of patients with rheumatoid arthritis. Unfortunately, this test has poor specificity and can be seen in other clinical disorders and even in healthy individuals.

References:

Smolen JS, Aletaha D, McInnes IB. Rheumatoid arthritis. Lancet. 2016 Oct 22;388(10055):2023-2038. doi: 10.1016/S0140-6736(16)30173-8. Epub 2016 May 3. Review. Erratum in: Lancet. 2016 Oct 22;388(10055):1984.

Singh JA, Saag KG, Bridges SL Jr, Akl EA, Bannuru RR, Sullivan MC, Vaysbrot E, McNaughton C, Osani M, Shmerling RH, Curtis JR, Furst DE, Parks D, Kavanaugh A, O'Dell J, King C, Leong A, Matteson EL, Schousboe JT, Drevlow B, Ginsberg S, Grober J, St Clair EW, Tindall E, Miller AS, McAlindon T. 2015 American College of Rheumatology Guideline for the Treatment of Rheumatoid Arthritis. Arthritis Rheumatol. 2016 Jan;68(1):1-26. doi: 10.1002/art.39480. Epub 2015 Nov 6. Review. PubMed PMID: 26545940.

Educational Objective:

Describe appropriate screening of chlamydia in women.

Key Point:

Screening woman at risk for asymptomatic chlamydia significantly reduces the incidence of PID.

Explanation:

Approximately 95% of genital chlamydial infections in women are asymptomatic. However, C trachomatis infection is a major cause of urethritis and cervicitis, and up to 40% of untreated cases of C trachomatis infection (symptomatic or asymptomatic) progress to PID. PID may result in ectopic pregnancy, infertility, and chronic pelvic pain.

Screening and treatment for chlamydia infection in high-risk, asymptomatic women has been demonstrated to significantly reduce the incidence of PID after 12 months of follow-up care. No studies have been published regarding the effectiveness of screening in women not at increased risk. Treatment of men does eradicate infection in men, but no evidence suggests that screening in men reduces transmission, acute infection, or sequelae in women.

Approximately 95% of men with C trachomatis infection are asymptomatic. Genital infection in men occasionally results in acute urethritis or epididymitis and, less often, in chronic prostatitis and reactive arthritis.

Reference:

Nelson HD, Zakher B, Cantor A, Deagas M, Pappas M. Screening for Gonorrhea and Chlamydia: Systematic Review to Update the U.S. Preventive Services Task Force Recommendations. 2014.

Educational Objective:

Identify the appropriate treatment for hidradenitis suppurativa.

Key Point:

Hidradenitis suppurativa can cause painful, acute cutaneous abscesses that can be treated with drainage.

Explanation:

This patient has hidradenitis suppurativa, which is a chronic disease of the apocrine sweat glands leading to plugging and clogging, pus formation, and possible scarring. It can occur in anyone but it is more likely to occur in African American women who are obese. The most common site is in the skin folds, including the axillae, groin, and under the breasts. The best treatment for a fluctuant lesion is incision and drainage with a short course of antibiotics (doxycycline, tetracycline, or minocycline) and pain medication, if necessary. Weight loss should always be considered; however, it is not the next best course of action with a fluctuant lesion. Surgical excision would be appropriate if the lesions had persisted for years and sinus tracts formed. Isotretinoin should be reserved for antibiotic-resistant cases and should never be the first choice of treatment in a patient such as the one in this case. Intralesional or injection triamcinolone acetonide is appropriate for small cysts and should be performed by a dermatologist.

Reference:

Hang B. Breast disorders. In: Tintinalli JE, et al, eds. Emergency Medicine: A Comprehensive Study Guide. 8th ed., 2016:675.