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572: ORAL VANCOMYCIN DESENSITIZATION IN A CRITICALLY ILL PATIENT WITH ALLERGIC REACTION

Learning Objectives: Ceftaroline is a fifth generation cephalosporin with broad spectrum activity including methicillin resistant Staphylococcus aureus (MRSA). Concern exists for resistance in treating infections from Enterobacteriaceae via AmpC β-lactamase induction. Methods: A 54-year-old male with a history of diabetes and hypertension presented with sepsis with multiple sources of infection. His imaging showed multiple cavitary lung nodules suggesting septic emboli. Vancomycin and piperacillin-tazobactam were started and blood cultures grew MRSA. On day 3, he was intubated for respiratory failure and initiated on vasopressors on day 4 for septic shock. Despite treatment with vancomycin blood cultures remained positive daily. The patient’s vancomycin level was therapeutic throughout this time and source control was unable to be obtained. On day 7, respiratory and blood cultures grew Enterobacter aerogenes. Vancomycin was discontinued and ceftaroline was initiated for MRSA treatment failure and to cover E. aerogenes. Expanded susceptibilities demonstrated E. aerogenes susceptible to ceftaroline. Repeat blood cultures were negative for E. aerogenes. Daptomycin was added for synergy with ceftaroline on day 14 after persistent MRSA-positive blood cultures. The patient required intermittent vasopressor support for shock. His blood cultures were negative after the antibiotic change. An epidural abscess was found on day 18. On day 20, the patient had a respiratory culture that grew E. aerogenes concerning for AmpC β-lactamase production. Resistance to ceftaroline was reported in expanded susceptibilities. Ciprofloxacin was added at this point and was changed five days later to sulfamethoxazole/trimethoprim (SMX/TMP) due to another respiratory culture growing resistant Escherichia coli. The patient remained on SMX/TMP for a total of 2 weeks and continued on daptomycin and ceftaroline for MRSA bacteremia. A transesophageal echocardiography performed on day 24 revealed no vegetations and imaging on day 25 demonstrated interval resolution of the epidural abscess. The patient was extubated on day 26 and transferred to a medical floor two days later. He was subsequently discharged on combination therapy for MRSA to complete a 6 week course for endocarditis. Results: Lack of data and experience exist using ceftaroline for infections caused by AmpC-producing Enterobacteriaceae. This case demonstrates potential for development of resistance and treatment failure when using ceftaroline for these infections.