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.
| Antimicrobial | Interpretation |
|---|---|
| Ampicillin | R |
| Amoxicillin-clavulanate | R |
| Cephalexin | R |
| Cephazolin * | R |
| Imipenem | I |
| Ertapenem | S |
| Gentamicin | S |
| Tobramycin | S |
| Trimethoprim/sulfamethoxazole | R |
| Ciprofloxacin | R |
| Nitrofurantoin | S |
| Fosfomycin | S |