Keys To Addressing MRSA In The Diabetic Foot
In addition to having diabetes for 12 years, she has hypertension and has been on dialysis for three years. The remainder of her social and past medical history is non-contributory.
On examination, the patient has palpable posterior tibial, dorsalis pedis and popliteal pulses bilaterally. She has absent protective sensation per Semmes Weinstein monofilament testing. There is a hemorrhagic bullous lesion encompassing the dorsal forefoot, extending from the base of her toes two through five and extending to the midshaft of the metatarsals. There is erythema encompassing the dorsal and lateral left foot to the level of the heel. Plantar to the distal fourth interspace, she has a hemorrhagic hyperkeratotic lesion communicating with the dorsal bulla via the webspace and there is a 2 mm pinpoint opening. There is plantar erythema extending across the metatarsophalangeal joints with tenderness to palpation at these levels. The tenderness is greatest to the fourth and fifth metatarsal heads, and fourth interspace.
The patient’s vital signs were stable, she was afebrile and the white blood cell count was elevated at 12. The patient went to the hospital. Given the severity of the infection and past history of ulceration with renal compromise, the patient started on vancomycin and received an incision and drainage. There was full thickness necrosis of the dorsal skin margins. This resulted in significant skin loss. There was no radiographic or intraoperative osseous involvement. Cultures were consistent with MRSA. Once the patient was stable and the white blood cell count trended down within normal range, she was discharged from the hospital. We prescribed doxycycline 100 mg PO bid for two weeks and employed an aggressive wound care regimen and VAC therapy (KCI) to healing.
The morbidity and mortality associated with MRSA infections is an alarming indicator of the urgency in addressing these infections in the diabetic population. Patients with diabetes whose MRSA infections resulted in amputation demonstrated a five times greater mortality rate in comparison to patients with non-MRSA infections.9
Additionally, researchers demonstrated that MRSA-related amputations have a higher stump infection rate of 24 percent.9 Re-infection rates with MRSA are also more frequent.
Therefore, even upon completion of therapy and appropriate management (whether it is surgical debridement, wound care or both), it is important to alert patients of colonization, the risk of carrier-states and long-term morbidity and mortality. Despite the subtle decline in HA-MRSA reported by the CDC, it is important to remember the unyielding state of CA-MRSA and its presence and contribution to healthcare-associated infections.10
The introduction of MRSA is not uncommon in the diabetic population and has become more prevalent today. Risk factors in this population go beyond the immunocompromised state of the patient with diabetes and also require a strong understanding of ulcer chronicity, prior hospitalization and chronic renal disease as associated risk factors for MRSA.
Dr. Hadi is the Director of the PAVE Program with the VA Puget Sound Healthcare System in Seattle and is a Fellow of the American College of Foot and Ankle Surgeons.