MRSA Infection of a Total Knee Replacement

Patient Presentation
K.S., a 75-year-old female presented to the orthopedic clinic for her two-week postoperative check up after her right total knee replacement. Her previous 4 day in-hospital stay had been unremarkable in which she was discharged home with physical therapy and a continuous passive motion machine.  She presented in the clinic with a temperature of 39.8 degrees Celsius with chills and general malaise.  She complained of shortness of breath and a low urine output x 2 days. Her VS were: BP 91/53, P 118, RR 16 and SaO2 91% on RA.  Her surgical incision was hot to touch, edematous and reddened, and had copious purulent fluid draining from the lower incision site. She also had 2+ pitting, bilateral lower leg edema. She was immediately admitted as direct admit to the hospital.

Diagnostic tests
Upon arrival to the hospital floor labs and tests were completed including a CBC, BMP, Coags, UA, anaerobic and aerobic wound cultures and blood cultures x 2.  An EKG was completed which showed NSR and the chest X-ray was grossly normal with bilateral lower lobe infiltrates. A renal US was performed to rule out renal obstruction. A CT scan of the right knee without IV contrast (due to elevated Cr) was completed revealing an abscess to the right knee.

Lab results were as follows:

WBC: 18                     BUN: 22                      Mg: 3.0
HBG: 28                      Cr: 2.0                         Phos: 4.9
HCT: 8.5                     Na: 129                       Ca: 8.2
                                    K: 5.3
                                    Cl: 105                      

UA: Grossly normal
Preliminary BC results: Gram + cocci in clusters.  (final analysis 2 days later +MRSA)
Preliminary WC results: Gram + cocci in clusters (final analysis 2 days later +MRSA)

Diagnosis
Right knee postop infection with abscess; with associated Septic Shock and Acute Renal Failure.

Treatment
K .S. was placed on contact isolation for the MRSA infection and put into a private room. She was given a 2 liter bolus of LR for her hypotension followed by LR @ 125 ml/hr for hydration and renal flushing. She was started on IV antibiotics vancomycin 1gm every 12 hours and Zosyn 3.375gm q6 hours. She was given 2 liter O2 per NC for her low SaO2 and q4 hour nebulizer treatments.

Outcome
Septic shock has a high death rate. The death rate depends on the patient's age and overall health, the cause of the infection, how many organs have failed, and how quickly and aggressively medical therapy is started.  K.S. will have long-term IV antibiotics for the MRSA infection and short-term hemodialysis to counteract the Acute Kidney Failure associated with the Septic Shock.  She will also undergo surgery to incise and drain her right knee MRSA infected abscess.  However if there are no other complications with the MRSA infection and her kidney function returns to normal, which is expected, K.S. has a good outlook to full recovery.

Case created by Kimberly Schuelke, 2011.