Rapid imipenem/cilastatin desensitization for multidrug-resistant Acinetobacter pneumonia

OBJECTIVE: To report a successful case of rapid imipenem desensitization in a critically ill patient with multidrug-resistant Acinetobacter baumannii ventilator-associated pnemonia (VAP). CASE SUMMARY: A 40-year-old white man who had a lengthy stay in the intensive care unit (ICU) following a motorcycle accident developed VAP caused by A. baumannii. Treatment with imipenem was necessary due to the bacteria's resistance to all other antibiotics. However, this patient was diagnosed with an allergy to imipenem following exposure earlier in his hospitalization in addition to a positive penicillin skin test. Thus, we attempted rapid desensitization to imipenem using a continuous infusion protocol. The patient was desensitized within 4 hours and was successfully treated for 21 days with a continuous infusion of imipenem combined with daily amikacin. He experienced no adverse reaction during the desensitization process or the remainder of his treatment course. DISCUSSION: The protocol used in this case was modified from a previously reported case, and differed in the speed of desensitization and total daily dose. We assumed that a more gradual escalation of the dose in our modified protocol would prevent the occurrence of adverse events, thereby resulting in more rapid desensitization. Rapid desensitization was necessary in this patient due to the presence of a life-threatening infection. The lower total daily dose of imipenem was in response to impaired renal function. CONCLUSIONS: Therapeutic options for multidrug-resistant pneumonia in the ICU are significantly limited in the presence of imipenem allergy. An option of last resort is to desensitize the patient using a rapid administration protocol. Our modified rapid imipenem desensitization protocol was successful and allowed for effective treatment of life-threatening pneumonia.