A 73 year old man presents to you one week after undergoing successful thyroid surgery. He has a fever(38.7°C), pain on passing urine and frequency. A urine sample was collected and demonstrated 4 + leukocytes and 4+ RBCs. After blood and urine cultures are obtained, you start him on ceftriaxone 1 gram Q24H to be administered in OPAT.
Two days later he is afebrile, and reports some improvement in urinary symptoms.
The laboratory reports a Serratia marcescens isolate [> 10⁵ CFU/mL] with the susceptibility pattern presented below.