Keys To Addressing MRSA In The Diabetic Foot

Start Page: 64
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Author(s): 
Suhad Hadi, DPM, FACFAS, and Randy Garr, DPM

   The patient’s past medical history is positive for type 2 diabetes, hypertension and peripheral vascular disease. He has a history of a partial hallux amputation on the left foot and partial second and third toe amputations on the right foot, which were well healed. The patient also had a femoral to popliteal bypass on the right extremity. He is married and denies tobacco and alcohol use. The patient cares for his wife, who is also a below-knee amputee and has diabetes. His last HgA1c was 7.2 and he monitors his blood glucose levels regularly. He denies fever and chills.

   Upon examination, the patient has palpable dorsalis pedis and posterior tibial pulses on the right and decreased posterior tibial and dorsalis pedis pulses on the left (1+). He has palpable popliteal bilateral with absent pedal and lower extremity hair growth. Protective sensation is absent to both feet proximal to the ankle with the Semmes Weinstein monofilament. Nails are intact bilaterally. He has a 1.5 cm ulceration to the plantar left fifth metatarsal base, which probes to the bone and tracks laterally to exit the ulcer site at the lateral fifth metatarsal base. There are surrounding macerated tissue margins to the ulcer sites. Seropurulent drainage is present. We irrigated the wound and took deep soft tissue cultures. Radiographs of the left foot did not demonstrate any osseous involvement and cortices were intact.

   Cultures were positive for MSSA. We reviewed the case with the infectious disease team and followed recommendations for the initiation of therapy with dicloxacillin (Diclocil, Bristol-Myers Squibb). Treatment also included aggressive offloading and wound care management with Iodosorb (Smith and Nephew) dressings daily with aggressive irrigation of the wound tract. The patient refused incision and drainage with operative debridement due to needing to care for his wife and father.

   Due to the death of his father and his mother-in-law within the same two-week period, the patient was absent to follow up in the clinic for one month. Upon his return, he had a full blown abscess and fluctuance encompassing the entire fifth metatarsal region. The patient had a new onset of pain to his foot at the fifth metatarsal and along the peroneals just distal to the lateral malleolus. He had nausea and complained of not being able to keep his food down. The patient was febrile with a 101º temperature and had an elevated white blood cell count of 16, findings that were concerning for systemic inflammatory response syndrome.

   We hospitalized the patient and started him on vancomycin and piperacillin/tazobactam (Zosyn, Pfizer) due to concern for MRSA and polymicrobial infection, given the wound’s chronicity and progression to a severe diabetic foot infection.
After two days on an intravenous antibiotic, the patient developed a localized fluctuant abscess in the region of the fifth metatarsal base extending dorsal and lateral. He then went to the operating room for a formal incision and drainage.

   Intraoperative findings were consistent with thick purulent drainage. The fifth metatarsal was gray and fragmented along the midshaft to the level of the base. The peroneus brevis tendon was shredded from the insertion to the distal lateral malleolus and there was hemorrhagic tissue along the sheath of the longus tendon proximal to the lateral malleolus. We resected the respective portion of the brevis and debrided the sheath of the longus.

   The cuboid had a dorsal erosion and cartilage was intact. The intraoperative biopsy and culture were consistent with osteomyelitis and new cultures revealed E. coli, Proteus and MRSA. Once the patient was stable postoperatively, the patient was discharged. He remained on the same antibiotic coverage (vancomycin 1,500 mg q12h and Zosyn 3 gm q8h) per the infectious disease team via PICC line placement and home nursing assistance. Due to the severity of his infection and required revascularization, antibiotic use continued for seven weeks without evidence of toxicity. Serial radiographs were without evidence of progressed osseous changes to the cuboid with full granulation of the wound.

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