UTI Case 1

A 27 year-old pregnant (34 weeks) woman was admitted to the emergency department with fever (38.7°C), pain on passing urine, abdominal pain and vomiting. A urine sample was collected and demonstrated 4 + leukocytes and 4+ RBCs. Empirical treatment with intravenous ceftriaxone was implemented. The patient is transferred to the gynecology ward and for the next two days she remains febrile with only slight clinical improvement.

On day two, the laboratory reports an Escherichia coli isolate [> 10⁵ CFU/mL] with the phenotype presented below. The MIC values were obtained with an automated system with the exception of fosfomycin and colistin which were tested with Etest and interpreted according to the current CLSI criteria.

Phenotypic tests (i.e. synergy with clavulanate) indicate that the E. coli isolate is NOT an extended-spectrum β-lactamase (ESBL) producer but it is confirmed to be an AMPc producer as suggested by the high MIC to cefazolin. The patient does not have renal or hepatic impairments, and her BMI is within normal values.

Ampicillin (≥ 32 mg/L) R
Amoxicillin-clavulanate (≥ 32 mg/L) R
Piperacillin-tazobactam (16 mg/L) S
Cephazolin (≥ 8 mg/L) R
Ceftriaxone (2 mg/L) I
Cefepime (≤ 1 mg/L) S
Imipenem (0.25 mg/L) S
Ertapenem (0.5 mg/L) S
Gentamicin (8 mg/L) I
Tobramycin (2 mg/L) S
Trimethoprim/sulfamethoxazole  (≥ 320 mg/L) R
Ciprofloxacin (2 mg/L) R
Nitrofurantoin (8 mg/L) S
Fosfomycin (64 mg/L) S
Colistin (0.5 mg/L) Not available


Would you change the therapy and, if so, to which agent?