A Streamlined Approach to Assessing Penicillin Allergy

Paul Santos, BS Pharm., Pharm. D

LRGHealthcare

Laconia, NH

Risks Associated With not Evaluating Individuals With a PCN Allergy

• Inferior Clinical Outcomes

• More SSI when PCN is the SOC and not used

• More deaths and inferior outcomes if PCN s not used in MSSA infections

• Longer hospitalizations and exposure to antibiotics associated with C. difficile and VRE

Reasons Why PCN Hypersensitivity Has Been Higher in the Past• “We discussed what to do with the pungent brown red powder. We decided to

dissolve it in saline and pass it through an E.K Seitz pad (asbestos pad) to sterilize it.” 1

• By 1946 there were 47 PCN ADE case reports• Allergic hydrarthrosis, urticaria, serum sickness, anaphylactic shock-like syndrome. All after

IM administration.

• Reaction frequency ~0.5% 2

• Now known that PCN left in solution degrades to adverse reactive substances

1. Grossman, CM. The first use of penicillin in the United States. Ann Intern Med. 2008; 149: 135–136

2. Suchecki, AI. Allergic reactions to penicillin. Br Med J. 1946; 2: 938–940

Beta-lactam Allergy TestingMethods

• Skin test with major / minor determinants

• Slow parenteral infusion challenge• Infused drug desired @ 5ml /hr 10ml/ hr then full rate if no reaction.

• PO challenge X1 or graded (two step)

Beta-lactam Allergy TestingMethods

• Skin test with major / minor determinants

• Slow parenteral infusion challenge• Infused drug desired @ 5ml /hr 10ml/ hr then full rate if no reaction.

• PO challenge X1 or graded (two step)

Allergy Assessment Tool

Penicillin Allergy Testing Protocol

-Assess likely hood of penicillin allergy (review algorithm)

-Define treatment plan:

A. GIVE PCN full dose

B. Amoxicillin challenge.

C. Skin test with Pre-Pen, if negative give amoxicillin challenge.

D. Call specialist or desensitization following published protocol.

E. Avoid B lactam antibiotics.

-Discuss treatment plan with provider.

Amoxicillin challenge procedure:

Patient must not be taking beta antagonists (beta -blockers) or H1 antagonists (antihistamines) for 24 hours prior to

challenge.

Existing IV access optional depending on allergy history.

Administer amoxicillin 250mg po X1 observe patient every 15 minutes for 1 hour. If the patient reports no adverse

events, the patient may receive a penicillin product. RN to document patient response. Pharmacy will remove

penicillin from the allergy profile. A note regarding the test will be made in the EMR.

An interview should take place with the patient where the following is discussed and then documented in

a “Clinical Pharmacy Consult Note” with the title “ANTIBIOTIC STEWARDSHIP”:

Inform the provider that the patient is a candidate for a pcn allergy testing and ask if they agree to

the assessment of the patient.

Ask the patient what they are allergic to?

What is the family allergy history?

Ask the patient to describe their allergy reaction.

When did the reaction occur?

How long of a delay after taking the penicillin product did the reaction occur?

What did the patient do about the reaction (e.g. Call their doctor, go to ED)? If they did go to the ED,

what treatment was given? Were they admitted?

If the patient is not a reliable historian, who provided the answers? Were they reliable?

Explain to the patient the risks of being mislabeled with a penicillin allergy (oftentimes involves the use of

more toxic, less effective, and more costly agents). In addition, data shows morbidity and mortality increases in patients

who are mislabeled as pcn allergic.

Interview Questions

Interview Questions (pg 2)

• Describe the amoxicillin challenge. (250mg x1, monitor patient q15 minutes x 1 hour. No VS needed.)

• Discuss the patient with Paul after interviewing the patient.

• Document that the patient understands the risks of being mislabeled with a pcn allergy and the possible risks (albeit small) of a type I hypersensitivity reaction.

• Document that the patient consents to the challenge.

• Discuss the amoxicillin challenge with the RN. Explain the plan to her/him and the need for RN documentation. Documentation site is variableper RN discretion.

• Document the interaction, consent and plan in the progress note. Add the outcome of the challenge to the progress note.

• If the test was negative, remove the allergy from the patients’ profile. Contact the patients’ pharmacy or nursing home personnel to inform them that the patient has been tested for a pcnallergy and no longer has a risk of immediate hypersensitivity. Give the patient a preprinted card that shows the de-labeling event.

Date Patient Reported AbxAllergy

Description of Allergy

Allergy Assessment Process Result

12/6/18 J.S. Macrolides,PCN, TCN

Not Sure, LTA* Amox challenge tolerated

12/6/18 C.T. Zosyn Hives on infusion Amox challenge tolerated

12/18/18 A.B. PCN May be rash, LTA Amox challenge tolerated

12/26/18 J.F. PCN 7yr old, bee stings IM PCN abdomen

Amox challenge tolerated

1/2/19 J.H. PCN Rash, 7 days after PCN start

Amox challenge tolerated

1/2/19 A.C. PCN IM, 1950’s Amox challenge tolerated

Date of

Admission

Date of

InterventionPatient Initials

P

aDate of Birth Reported Abx Allergy

Description of Allergy by patient

*LTA = Long time agoFurther Investigational Info Allergy Assessment Process Result

12/6/2018 12/6/2018 J.S. J9/5/1935 Macrolides,PCN, TCN Not Sure, LTA* Amox challenge tolerated

12/6/2018 12/6/2018 B.T.C.B

e5/21/1943 Zosyn Hives on infusion Amox challenge tolerated

12/18/2018 12/18/2018 A.B. A3/25/1932 PCN May be rash, LTA Amox challenge tolerated

12/26/2018 12/26/2018 J.F.J

o5/13/1949 PCN

7yr old, bee stings IM PCN

abdomen 1960’sAmox challenge tolerated

1/30/2019 2/1/2019 A.G.

A

m

a

n

5/6/1976 PCN, Bactrim Rash

Head to toe "sunburn like" rash

as a child which lasted a month

and did not require an

treatment

Amox challenge tolerated

1/2/2019 1/2/2019 J.H. J3/2/1984 PCN Rash 7 days after PCN start Amox challenge tolerated

1/2/2019 1/2/2019 A.C. A3/17/1942 PCN IM, 1950’s Amox challenge tolerated

1/7/2019 1/7/2019 M.A.M

i12/16/1966 PCN Anaphylaxis as child

Did not go to hospital for

treatmentAmox challenge tolerated

1/10/2019 1/10/2019 K.D.K

a11/1/1957 Amoxicillin Hives as child > 48hr post 1st dose Amox challenge tolerated

1/14/2019 1/14/2019 R.WR

e3/28/1950 “PCN” in ICU

Gums swelled, son has Hx PCN

allergyAmox challenge tolerated

1/15/2019 1/18/2019 A.G.A

l2/2/1994 PCN Swelling

anaphylaxis as a childAmox challenge tolerated

1/15/2019 1/15/2019 L.P. L9/6/1936 PCN 82yo, PCN allergy as child rash Zosyn full dose tolerated

1/28/2019 1/28/2019 C.C. C9/27/1985 Amoxicillin Rash in teen years 1960’s Not immediate Amox challenge tolerated

3/1/2019 3/1/2019 L.H. L3/13/1963 PCN anaphylaxis “Red butt” as child 1980’s Amox challenge tolerated

3/12/2019 3/14/2019 M.M

M

a

r

2/3/1952 PCNAnaphylaxis, rash, tongue

swelling 1970’s

Post-op, no clear S+S of

anaphylaxis, only SOBAmox challenge tolerated

Conclusions

• Few patients who state they are allergic to penicillin actually are allergic

• It is clear that patients have a higher risk of morbidity and mortality when misdiagnosed as penicillin allergic.

• A few simple questions go a long way to assessing the risk of a significant penicillin allergy

• Cephalosporin allergies are not a cross-reactive class effect.• Cefazolin and ceftriaxone do not share a similar side chain with pcn

• While penicillin skin testing is the gold standard, the amoxicillin challenge method is clearly accepted as an alternative standard of care.