Clinical Diabetes 22:144-145, 2004
© American Diabetes Association ®, Inc., 2004
Case Study: Skin Infection in a Diabetic Patient Related to Contamination of an Insulin Bottle
Irma Gazeroglu, MD,
Michael Borenstein, MD, PhD and
Maria P. Solano, MD
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Presentation
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D.P. is a 59-year-old white Hispanic woman with a 12-year history of type 2
diabetes treated with a thiazolidindione and multiple daily injections of
insulin. She presented to the outpatient clinic with a 10-week history of
painful skin lesions on her abdomen that had been increasing in size. The
lesions developed at the site of insulin injections. She was injecting in the
abdomen, using a new needle each time. She had received a 14-day course of
levofloxacin 7 weeks before the clinic visit and had been instructed to change
the insulin bottles and to use her arms for injection. The skin lesions did
not seem to improve, but she did not developed new lesions. She denied fever
or other constitutional symptoms.
Her medical history was significant for severe asthma requiring chronic
oral steroids and hypertension. Her medications included rosiglitazone;
irbesartan; prednisone, 20 mg daily; bronchodilators; and glargine and aspart
insulins. Her glycemic control was poor, with a hemoglobin A1c
result of 13.2%.
On physical examination, she had Cushingoid features and did not appear
ill. Her blood pressure was 120/60 mmHg, heart rate 84 bpm, respiratory rate
16 rpm, and temperature 98.4° F. On her abdomen, she had multiple tender,
red, indurated, hemorrhagic crusted papules and nodules, 0.5-2 cm in size in
the periumbilical region bilaterally
(Figure 1). There was no
peripheral edema, and there were no lesions elsewhere on her body.
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Figure 1. Pink nodules and pink, crusted, scaly papules coalescing into
plaques on the right mid-abdomen.
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Routine laboratory tests, including leukocyte count with differential,
platelets, electrolytes, creatinine, and liver enzymes, were within normal
ranges.
A skin biopsy was performed from one of the nodules and was sent for
histopathology and culture.
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Questions
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- What is the microorganism involved in this patient's skin infection?
- How was the insulin bottle contaminated with the etiologic agent?
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Commentary
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The biopsy demonstrated numerous acid fast bacilli in the inflamed dermis
(Figure 2). Unfortunately, due
to lab error, a culture was not performed.
In this patient, the insulin bottle was the culprit. After she changed it,
she did not develop new lesions. Upon further questioning, she admitted that
there was water dripping in the refrigerator where she kept the insulin
bottle, as a possible explanation of how the bottle was contaminated with the
environmental pathogen.
D.P. was treated with clarithromycin for 3 months with resolution of the
lesions and only mild residual hyperpigmentation in the area.
Occasionally, mycobacteria are isolated from nodular skin lesions of
immunosuppressed patients. Many cases are linked to injections, and diabetic
patients are at especially high risk. The skin infections are usually due to
M. abcessus, M. chelonea, M. fortuitum, and M. kansasii.
Nontuberculous mycobacteria grow slowly. Even the rapid growers may take
3-7 days to form visible colonies on media, whereas slow-growing mycobacteria
take weeks or do not grow at all. The slow growth complicates antibiotic
susceptibility testing. Antibiotics may be degraded during prolonged
incubation.
These mycobacteria are notoriously resistant to most antituberculosis
drugs. Debridement is best combined with two or three antibiotic drugs. Most
commonly used antibiotics are clarithromycin, clofazimine, amikacin,
rifabutin, and sulfonamide.
It is important to consider the possibility of mycobacterial infection in
cases that do not respond to standard antibiotic therapy. It is essential to
perform skin biopsy and cultures to evaluate the lesions in order to guide
therapy.
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Clinical Pearls
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- It is important to keep in mind the rare but potential skin infection with
atypical mycobacteria in diabetic patients who do not respond to antibiotic
therapy for common skin pathogens.
- When suspected, it is imperative to inform the lab technician to use
special media for atypical mycobacterium isolation. Skin biopsy and cultures
are essential to guide the therapy.
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Footnotes
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Irma Gazeroglu, MD, is a fellow at the University of Miami, Division of
Endocrinology, Diabetes, and Metabolism; Michael Borenstein, MD,PhD, is a
resident at the University of Miami, Department of Dermatology; and Maria P.
Solano, MD, is an assistant professor of medicine at the University of Miami,
Division of Endocrinology, Diabetes, and Metabolism in Miami, Fla.
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