October 31, 2024

23-year-old with type 1 diabetes presenting with large rash

By Med-Challenger · 2 minute read

A 23-year-old man from Massachusetts with a history of well-controlled type 1 diabetes mellitus presents with a rash (see Figure).

image (11)

He is taking insulin for his diabetes but is on no other medications.

He does not recall any tick bites, but he does like to be outdoors. He acknowledges that the outdoor area outdoors he enjoys most is infested with ticks. He is afebrile and does not have any other symptoms or findings on physical examination.

Which of the following is an appropriate next step in this patient’s care?

Enzyme-linked immunosorbent assay and confirmatory Western blot
Doxycycline for 10 to 14 days, or amoxicillin or cefuroxime for 14 days
Doxycycline for 7-14 days
Amoxicillin for 28 days

The correct answer is:

Doxycycline for 10 to 14 days, or amoxicillin or cefuroxime for 14 days

Key Point:

Lyme disease can be diagnosed with confidence on clinical grounds alone (recommended by 2021 National guidelines recommend) when a patient from an endemic area presents with typical erythema migrans.

Explanation:

Erythema migrans is the most common clinical feature of Lyme disease. In one series of reported cases, rash by itself was seen in nearly 90% of cases. It typically appears 1 to 2 weeks after the tick detaches. The typical rash is round or oval, slightly papular, erythematous, and usually larger than 2 inches in diameter. Most often, it presents as a single lesion.

Lyme disease is the most common vector-borne illness in the United States. In an endemic area, clinical findings, such as erythema migrans, are sufficient to make the diagnosis of Lyme disease and no additional testing is required. This is important because approximately 70% to 75% of Americans with early Lyme disease do not recall a tick bite, which, of course, would help strengthen the consideration of Lyme disease.

With approximately 30,000 cases of Lyme disease reported to the Centers for Disease Control and Prevention each year, recognizing that Lyme disease can be diagnosed on clinical grounds alone in endemic areas significantly decreases the time and cost of diagnosis and reporting.

National Lyme disease guidelines updated in 2021 call for the following antibiotic options for adults with early disseminated or early localized Lyme disease associated with erythema migrans:

▪ Doxycycline (100 mg twice a day) for 10 to 14 days (preferred treatment in adults)

▪ Amoxicillin (500 mg 3 times a day) for 14 days

▪ Cefuroxime Axetil (500 mg twice a day) for 14 days

In patients older than 8 years and not pregnant, doxycycline is the first choice of treatment; amoxicillin is a second option. Due to its cost, cefuroxime is usually reserved for patients who cannot take either of the other 2 antibiotics.

The patient’s diabetes does not influence treatment; however, active Lyme disease will result in an increase in serum glucose levels. In cases where Lyme disease results in carditis or meningitis, parenteral antibiotics are recommended.

Note that the Infectious Disease Society’s early 2021 guidelines recommend doxycycline 10 days for erythema migrans treatment, whereas the August 2021 CDC guidelines recommend 10-14 days of doxycycline for erythema migrans.

References:

Treatment for Erythema migrans. Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of Vector-Borne Diseases (DVBD). https://www.cdc.gov/lyme/treatment/index.html (Updated August 23, 2021) (Accessed Sept 15, 2021)

Lantos PM, et al. Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA), American Academy of Neurology (AAN), and American College of Rheumatology (ACR): 2020 Guidelines for the Prevention, Diagnosis, and Treatment of Lyme Disease. Clinical Infectious Diseases, Volume 72, Issue 1, 1 January 2021, Pages e1-e48,

Wormser GP. Lyme disease (chapter 321). In: Goldman L, Schafer A. Goldman-Cecil Medicine. 25th ed., 2016:2021-2027.

This question appears in Med-Challenger Internal Medicine Review with CME.

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