An 85-year-old female presented to the PACE clinic with large skin abscess and a fever of 101 degrees Fahrenheit. Past medical history is significant for Stage 5 chronic kidney disease, with an estimated GFR of 13 mL/min, and psoriasis for which she takes chronic daily prednisone. Since this patient had a history of recurrent skin and soft tissue infections over the past year, the MD decided to hold initial antibiotic treatment, perform an incision and drainage, and order skin cultures and sensitivities. The following day cultures were obtained and it was determined that Enterobacter cloacae was the infectious etiology of this skin infection. The sensitivity panel revealed the following:
Ampicillin (R) Doxycycline (R)
Augmentin (R) Gentamicin (S)
Ceftazidime (S) Tetracycline (R)
Cefuroxime (R) SMX/TMP (S)
Given this labwork, the PACE doctor decided to initiate therapy with ciprofloxacin 500mg every 12 hours for 21 days.
Upon receiving the prescription, the CareKinesis clinical pharmacist was concerned regarding the dosing of the ciprofloxacin due to the patient’s degree of renal dysfunction. Failure to adjust the dosing of this drug in renal dysfunction, and particularly given the length of therapy required, would lead to decreased drug clearance and higher drug levels which may have dose-dependent sequela, namely: QT prolongation and risk of tendon rupture.
This patient possessed two additional independent risk factors for quinolone-associated tendon rupture/inflammation: use of concomitant corticosteroids (daily prednisone) and an age greater than 60 (85-years-old). The CK clinical pharmacist explained to the doctor the aforementioned risks that may occur if dose adjustment does not occur, and also explained that the recommended adjustment based on renal function is quite inconvenient and a “nursing-nightmare”: 500 mg every 18 hours. Unfortunately, given this patient’s degree of renal dysfunction the only other oral option based on the sensitivity panel, SMX/TMP, would be contraindicated. Furthermore, considering the PACE-model, the goal was to provide outpatient treatment and to avoid IV antibiotics with a hospital admission. Therefore, the oral quinolone therapeutic class was the best option. The CK clinical pharmacist recommended levofloxacin 750mg as a loading dose on day 1 followed by 500mg PO every 48 hours for 20 total days of therapy (corresponding therapy to 750mg daily dosing in a patient with normal renal function).
Since this intervention and completion of the levofloxacin at this dose for renal dysfunction, the patient tolerated the antibiotic therapy without adverse effects and the infection resolved.