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Antibiotic Therapy in the Penicillin Allergic
Patient in Critical Care
Burke A. Cunha
Infectious Disease Division, Winthrop-University Hospital, Mineola, New York, and State University of
New York School of Medicine, Stony Brook, New York, U.S.A.INTRODUCTION
Empiric antimicrobial therapy is a necessity in the critically ill patient with a life-threatening
infectious disease. Several factors go into antibiotic selection including (i) spectrum of activity
against the presumed pathogens, which is related to the source of infection or organ system
involved; (ii) pharmacokinetic and pharmacodynamic considerations which affect dosing and
concentration in the source organ for the sepsis; and (iii) the resistance potential of the
antibiotic needs to be considered. Although cure of the patient is the immediate priority, drug
selection has a subsequent effect on the flora of the critical care unit (CCU) and eventually may
impact on the flora of the hospital. The fourth consideration is the safety profile of the drug,
which has to do with adverse side effects and interactions, as well as the patient’s allergic drug
history. One of the most common problems encountered in treating critically ill patients is the
question of penicillin allergy.
DETERMINING THE TYPE OF PENICILLIN ALLERGY
There are no good data on the incidence of penicillin allergy. Some studies are done using skin
testing to derive the data. Other studies are based on clinical information, i.e., questioning the
patient or relatives regarding the nature of the penicillin allergy. Often penicillin allergy is
mentioned, but further or detailed question reveals that it is not truly an allergic reaction at all.
Patients, if they are able to respond, are either vague or very clear about the nature of their
penicillin allergy. In the critical care setting, there is often no way to get a drug allergy history.
Relatives are usually uncertain as to the nature of the allergic reaction of the patient. There is
poor correlation between the patient reporting penicillin allergy and subsequent penicillin skin
testing. In critical care medicine, the patient’s history is the only piece of information that the
clinician has to work with to make a decision regarding the nature of possible penicillin allergy
(1–6). Becauseb-lactam antibiotics are one of the most common classes of antibiotics used, the
question of using these agents in patients with penicillin allergy is a daily consideration. The
clinical approach to the patient with a potential skin allergy involves determining the nature of
the penicillin allergy as well as selecting an agent with a spectrum appropriate to the organ
source of the sepsis. Penicillin allergies may be considered as those that result in anaphylactic
reactions, i.e., anaphylaxis, laryngospasm, bronchospasm, hypotension, or total body hives,
and those that result in non-anaphylactic reactions, i.e., drug fever or skin rash. Patients with
non-anaphylactoid skin reactions may safely be givenb-lactam antibiotics with a spectrum
appropriate to the site of infection. Patients with a history of an anaphylactic reaction to
penicillin should be treated with an antibiotic of another class that has a spectrum appropriate
to the focus of infection (7–11).
PENICILLIN ALLERGIC REACTIONS
In the critical care setting, when urgent antimicrobial therapy is necessary, there is no time for
skin testing to rule out or confirm penicillin allergy. Patients who are communicative can
indicate, on direct questioning, the nature of their penicillin reaction. Often times what is
considered a penicillin reaction by the patient is in fact an unrelated drug side effect. Patients
often report a vague history of penicillin allergy during childhood that has not recurred
subsequently, while others report penicillin allergy occurred in close relatives but not
themselves. Some patients were told they had a drug fever due to penicillin, but did not