pcn allergy and keflex

[caligas]

If your surgeon is insistent wanting to give keflex, how much of a fight do you put about about giving it to a pcn allergic (hives etc) pt?

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[deleted171991]

None, unless there is history of anaphylaxis. The overlap is about 7% or less. I still have to see a patient severely allergic to both.

Also, I tend to give way less importance to minor PCN allergy in childhood, in the 50's-60's. My guess is that those people where actually allergic to the excipient in the formula (the prevalence is much higher than in children exposed to modern penicillin nowadays).

 

[BuzzPhreed]

If your surgeon is insistent wanting to give keflex, how much of a fight do you put about about giving it to a pcn allergic (hives etc) pt?

I generally don't give oral antibiotics to my patients. I do give Kefzol.

 

[fakin' the funk]

If your surgeon is insistent wanting to give keflex, how much of a fight do you put about about giving it to a pcn allergic (hives etc) pt?

I haven't met a surgeon who's "insistent" on giving cefazolin.
If there's a real concern about the patient having a severe systemic reaction...I mean, they don't want their patient to anaphylax either.
I suppose that since vanco takes time to get an run that would be one reason to "insist" on a cephalosporin.

To answer your question, unless the reaction was true anaphylaxis/oid, they get cefazolin, for the aforementioned reasons.

 

[Planktonmd]

I still have to see a patient who was classified allergic to penicillin react to cephalosporins!

 

[periopdoc]

Cross reactivity between Penicillin and Cephalosporins is largely a theoretical construct that is not borne out by the evidence. The initial studies that produced the 10% cross reactivity rate were flawed in that early preparations of cephalosporins were contaminated with small amounts of penicillin, and early preparations of penicillin were contaminated with small amounts of cephalosporins.

More recent studies fail to support the claimed cross reactivity and, in fact, demonstrate that cross reactivity between penicillin and cephalosporins is lower than cross reactivity between penicillin and other antibiotics. Primary cephalosporin allergy runs about 1-3% in the general population. Penicillin allergic patients are 3x more likely to be allergic to unrelated antibiotics. The supposed cross reactivity is, mostly, a reflection of the fact that Pen allergic patients are more likely to have primary allergic reactions to other medications too, superimposed on the expected rate of reaction in the general population.

After introduction into the body, the penicillin beta-lactam ring remains stable while the cephalosporin ring is immediately degraded. Any type of cross reactivity is more likely due to side chain similarity.

So, the wise thing to do is to avoid cephalosporins with similar side chains in patients with documented typical IgE mediated reactions, and patients with documented IgE penicillin antibodies. For patients with mild reactions, or undocumented reactions, the use of cephalosporins is not contraindicated and is medico-legally and morally defensible.

- bsd

 

[periopdoc]

Note that the Cefazolin side chain structure is dis-similar to all penicillins and all other cephalosporins. Therefore it should have no cross-reactivity with any penicillin or any other cephalosporin.

- bsd

 

[periopdoc]

I have yet to encounter the surgeon that is insistent on giving Ancef to their Pcn allergic patient. It is always the other way around.

I am constantly trying to educate them that they should order Ancef instead of some crappy alternative that either doesn't have as good a coverage or is WAY too broad spectrum for the task at hand.

Except for the Gynecologists. They aren't even open to hearing that they aren't doing their patients any favors when they blast them with multiple, potent, wide-spectrum antibiotics before routine procedures. Why would I expect them to be open to sensible, evidence based approaches to dealing with antibiotic reactions and allergies?

- bsd

 

[caligas]

Cross reactivity between Penicillin and Cephalosporins is largely a theoretical construct that is not borne out by the evidence. The initial studies that produced the 10% cross reactivity rate were flawed in that early preparations of cephalosporins were contaminated with small amounts of penicillin, and early preparations of penicillin were contaminated with small amounts of cephalosporins.

More recent studies fail to support the claimed cross reactivity and, in fact, demonstrate that cross reactivity between penicillin and cephalosporins is lower than cross reactivity between penicillin and other antibiotics. Primary cephalosporin allergy runs about 1-3% in the general population. Penicillin allergic patients are 3x more likely to be allergic to unrelated antibiotics. The supposed cross reactivity is, mostly, a reflection of the fact that Pen allergic patients are more likely to have primary allergic reactions to other medications too, superimposed on the expected rate of reaction in the general population.

After introduction into the body, the penicillin beta-lactam ring remains stable while the cephalosporin ring is immediately degraded. Any type of cross reactivity is more likely due to side chain similarity.

So, the wise thing to do is to avoid cephalosporins with similar side chains in patients with documented typical IgE mediated reactions, and patients with documented IgE penicillin antibodies. For patients with mild reactions, or undocumented reactions, the use of cephalosporins is not contraindicated and is medico-legally and morally defensible.

- bsd

I have yet to see a patient with any formal documentation from an allergist etc. Have to go by history, which is usually sketchy.

 

[periopdoc]

Exactly. As I said above, absent the lack of documented allergy, or compelling story (I was admitted to ICU, intubated, etc), give the Ancef. Even if it was a true Pcn allergy (unlikely), Ancef shares no side chain similarity with any of the Pcns, and the beta lactam ring is too unstable to provoke an IgE response.

The chance of inappropriate antibiotic coverage is much, much, much higher than any chance of there actually being a true IgE mediated Pcn allergy plus there being any true cross reactivity.

Just be ready to defend yourself in peer review if the patient just so happens to have a primary cephalosporin allergy. I know that I am prepared.


- POD

 

[Noyac]

I give it.

 

[OB1🤙]

Good stuff POD.

 

[Spt30]

Cross reactivity between Penicillin and Cephalosporins is largely a theoretical construct that is not borne out by the evidence. The initial studies that produced the 10% cross reactivity rate were flawed in that early preparations of cephalosporins were contaminated with small amounts of penicillin, and early preparations of penicillin were contaminated with small amounts of cephalosporins.

More recent studies fail to support the claimed cross reactivity and, in fact, demonstrate that cross reactivity between penicillin and cephalosporins is lower than cross reactivity between penicillin and other antibiotics. Primary cephalosporin allergy runs about 1-3% in the general population. Penicillin allergic patients are 3x more likely to be allergic to unrelated antibiotics. The supposed cross reactivity is, mostly, a reflection of the fact that Pen allergic patients are more likely to have primary allergic reactions to other medications too, superimposed on the expected rate of reaction in the general population.

After introduction into the body, the penicillin beta-lactam ring remains stable while the cephalosporin ring is immediately degraded. Any type of cross reactivity is more likely due to side chain similarity.

So, the wise thing to do is to avoid cephalosporins with similar side chains in patients with documented typical IgE mediated reactions, and patients with documented IgE penicillin antibodies. For patients with mild reactions, or undocumented reactions, the use of cephalosporins is not contraindicated and is medico-legally and morally defensible.

- bsd

I'm an allergist/immunologist and periopdoc you are absolutely correct. One study looked at patients who had sxs consistent with a type I reaction to PCN. These patients were subsequently given a cephalosporin. Out of 500 or so patients, no one had a reaction.

So when I'm asked this question. I say give the cephalosporin.

Periopdoc, your knowledge in this subject is impressive. Were you a budding allergist at some point?

 

[DrAwesomo]

If the PCN allergic reaction was anaphylaxis, then I would not give it. In other cases, there's only 10% chance the person will get hives/rash which is easily treatable with benadryl and steroid. You can even "pretreat" by giving solumedrol 125mg and benadryl 25mg IV which probably would bring the number down to 0.1%.

 

[caligas]

If the PCN allergic reaction was anaphylaxis, then I would not give it. In other cases, there's only 10% chance the person will get hives/rash which is easily treatable with benadryl and steroid. You can even "pretreat" by giving solumedrol 125mg and benadryl 25mg IV which probably would bring the number down to 0.1%.

Ive done that, but I wonder If we are just masking any reaction should it occur, setting up a problem with a later dose outside of the safety of the o.r.

 

[btbam]

Periop, do you have any links to the papers you mentioned? I'd love to circulate them at work so we can put these silly dogmas to rest.

 

[Noyac]

Ive done that, but I wonder If we are just masking any reaction should it occur, setting up a problem with a later dose outside of the safety of the o.r.

That is the Dilemma. Do we mask a reaction with steroids which may delay our recognition of a real problem or do we minimize a espouse that might have been worse if steroids were not given? I say both.

 

[periopdoc]

I have had some requests for references in my PMs too. I'm just getting back from travelling with nothing but my phone for posting so I haven't had the papers in front of me. When I get caught up with the backlog of work I have here I will dig out the papers. In the meantime, Google has what you need, and gathering your own evidence will be superior as you may find articles that I have missed that will flesh out the discussion.

A good starting point would be to Google "penicillin cephalosporin cross-reactivity." In the first few pages of results, there should be some PPT and PDF files of presentations that have been made on the topic. They will give you an overview and references to build off of. It should also bring up some primary citations that would be useful.

- bsd

 

[Ignatius J]

I believe if you give a cephalosporin to a PCN-allergic patient you are no longer considered SCIP compliant. Reason enough right there.

Edit: after reading PODs post above, CMS can suck it. Bravo.

 

[Scotty_G]

I believe this is the study you are referring to:
http://www.ncbi.nlm.nih.gov/pubmed/11755324

 

[BLADEMDA]

Am J Med. 2006 Apr;119(4):354.e11-9.
Is there cross-reactivity between penicillins and cephalosporins?
Apter AJ1, Kinman JL, Bilker WB, Herlim M, Margolis DJ, Lautenbach E, Hennessy S, Strom BL.
Author information

Abstract
BACKGROUND:
We sought to determine the risk of an allergic reaction to a cephalosporin exposure in those with prior penicillin reactions.

METHODS:
We conducted a retrospective cohort study using the United Kingdom General Practice Research Database. We selected all patients receiving a prescription for penicillin followed by a prescription for a cephalosporin and identified allergic-like events within 30 days after each prescription. Allergic events were defined by 2 sets of codes: 1 more restrictive, 1 more inclusive. Comparison was made with a population of patients receiving a prescription for a penicillin followed by a prescription for a sulfonamide antibiotic.

RESULTS:
A total of 3,375,162 patients received a penicillin; 506,679 (15%) received a subsequent cephalosporin. Among patients receiving a penicillin followed by a cephalosporin, the unadjusted risk ratio of an allergic-like event for those who had a prior event, compared with those who had no such prior event, narrowly defined, was 10.1 (confidence interval 7.4-13.8). The absolute risk of anaphylaxis after a cephalosporin was less than 0.001%. The unadjusted risk ratio for sulfonamide antibiotic, rather than cephalosporin after penicillin allergic-like events was 7.2 (confidence interval 3.8-13.5).

CONCLUSION:
Patients with allergic-like events after penicillin had a markedly increased risk of events after either subsequent cephalosporins or sulfonamide antibiotics. Cross-reactivity is not an adequate explanation for this increased risk, and the risk of anaphylaxis is very low. Thus, our data indicate that cephalosporins can be considered for patients with penicillin allergy.

 

[periopdoc]

Periopdoc, your knowledge in this subject is impressive. Were you a budding allergist at some point?

Thanks for the kudos. Some of my favorite subjects in med school were endocrinology, immunology, hematology, and nephrology. I doubt I am smart enough to do any of them as a career, but I still enjoy studying them. The guys I worked with in these specialties were the smartest people I have ever encountered.

- pod

 

[periopdoc]

Sorry for the delay in posting some references. I have been trying to find ones that are publicly available without subscription, which has been difficult.

A good place to start is any of the review articles by Michael E. Pichichero out of Rochester. He authored a great CME review article in Annals of Allergy, Asthma & Immunology. I believe this is the article (Penicillin and Cephalosporin Allergy), but I don't have access to it from my current institution.

He also authored a good article in Pediatrics, A Review of Evidence Supporting the American Academy of Pediatrics Recommendation for Prescribing Cephalosporin Antibiotics for Penicillin-Allergic Patients. That is behind a subscription firewall, but you may have access through your institution. I have access to it through other sources.

He authored this article in The Journal of Family Practice. Cephalosporins can be prescribed safely for penicillin-allergic patients. It isn't as thorough as some of his others, but it isn't behind a subscription firewall, and it is a good, more broad overview than the others.

The American Academy of Allergy, Asthma, and Immunology has the following work group report publicly available.
Cephalosporin Administration to Patients with a History of Penicillin Allergy. It is probably the best, publicly available overview of the issue. Easy read that touches on most of the major issues and has good references for folks who want to dig deeper.

Obviously, these articles can be mined for references as needed.

- pod

 

[deleted171991]

Misconceptions Surrounding Penicillin Allergy:... : Anesthesia & Analgesia

Hat tip: Anesthesia&CritCare (@AnesthCritCare) | Twitter

 

[2Fast2Des]

Is it the anesthesiologist's role to dictate or challenge the surgeon's preference for antibiotics? Like you said if they are asking to give broad spectrum when it is not needed, aren't we not contributing to increased antibiotic resistance? We had one famous surgeon who would use the same antibiotics cocktail that was overkill as his standard routine. How does one practice antibiotic stewardship in the periop setting?

 

[Psai]

Is it the anesthesiologist's role to dictate or challenge the surgeon's preference for antibiotics? Like you said if they are asking to give broad spectrum when it is not needed, aren't we not contributing to increased antibiotic resistance? We had one famous surgeon who would use the same antibiotics cocktail that was overkill as his standard routine. How does one practice antibiotic stewardship in the periop setting?

If they ask me for clinda or something because they are scared of ancef I say no I'm giving ancef anyway and theyre like ok

Sometimes they ask why I tell them why and theyre like ok

 

[OB1🤙]

If they ask me for clinda or something because they are scared of ancef I say no I'm giving ancef anyway and theyre like ok

Sometimes they ask why I tell them why and theyre like ok

Exactly this.

 

[Urzuz]

Is it the anesthesiologist's role to dictate or challenge the surgeon's preference for antibiotics? Like you said if they are asking to give broad spectrum when it is not needed, aren't we not contributing to increased antibiotic resistance? We had one famous surgeon who would use the same antibiotics cocktail that was overkill as his standard routine. How does one practice antibiotic stewardship in the periop setting?

We are consultants. The surgeons I work with regularly almost always defer to me in terms of giving drugs that may be considered "questionable" (cefazolin in a PCN allergic patient, TXA to a patient with a remote history of MI, etc etc). Usually I provide my rationale for giving/not giving a certain drug and they're fine with it. If I see that they have ordered clindamycin or whatever instead of cefazolin on a PCN-allergic patient out of fear for cross-reactivity, I use the opportunity to educate them and say if cefazolin is the more appropriate drug for prophylaxis, then they should get cefazolin.

 

[deleted875186]

I don’t see the big deal for a one time dose of clinda versus a one time dose of of cefazolin. I was under the impression the coverage is prett similar, just a little more anearobkc coverage.

I almost always give cefazolin and surgeons are always ok if I say I’m comfortable with an old or non serious PCN reaction, but I also see no downside to a single dose of clinda for any reaction that sounds somewhat suspect.

 

[Psai]

I don’t see the big deal for a one time dose of clinda versus a one time dose of of cefazolin. I was under the impression the coverage is prett similar, just a little more anearobkc coverage.

I almost always give cefazolin and surgeons are always ok if I say I’m comfortable with an old or non serious PCN reaction, but I also see no downside to a single dose of clinda for any reaction that sounds somewhat suspect.

More diarrhea, more c diff, increased resistance in mrsa. I want to save it if I can.

 

[deleted875186]

More diarrhea, more c diff, increased resistance in mrsa. I want to save it if I can.

Sure, resistance is an issue with overuse. We hardly ever treat MRSa with clinda though, it’s usually already 50% resistance in some places. I suppose you could get cdiff from a single dose, but you could get it from ancef as well. It’s not clear to me how much bigger a risk it is woth a single prophylactic dose.

 

[deleted162650]

I just give the Ancef and then say “I’ll let ya know if they anaphylax.”

 

[Norepi]

The Impact of a Reported Penicillin Allergy on Surgical Site Infection Risk - PubMed

Patients with a reported penicillin allergy had a 50% increased odds of SSI, attributable to the receipt of second-line perioperative antibiotics. Clarification of penicillin allergies as part of routine preoperative care may decrease SSI risk.

www.ncbi.nlm.nih.gov

The Impact of a Reported Penicillin Allergy on Surgical Site Infection Risk.
Blumenthal KG1,2,3,4, Ryan EE5,6, Li Y1,2, Lee H4,7, Kuhlen JL8, Shenoy ES2,4,5,6.
Author information

Abstract
Background:
A reported penicillin allergy may compromise receipt of recommended antibiotic prophylaxis intended to prevent surgical site infections (SSIs). Most patients with a reported penicillin allergy are not allergic. We determined the impact of a reported penicillin allergy on the development of SSIs.
Methods:
In this retrospective cohort study of Massachusetts General Hospital hip arthroplasty, knee arthroplasty, hysterectomy, colon surgery, and coronary artery bypass grafting patients from 2010 to 2014, we compared patients with and without a reported penicillin allergy. The primary outcome was an SSI, as defined by the Centers for Disease Control and Prevention's National Healthcare Safety Network. The secondary outcome was perioperative antibiotic use.
Results:
Of 8385 patients who underwent 9004 procedures, 922 (11%) reported a penicillin allergy, and 241 (2.7%) had an SSI. In multivariable logistic regression, patients reporting a penicillin allergy had increased odds (adjusted odds ratio, 1.51; 95% confidence interval, 1.02-2.22) of SSI. Penicillin allergy reporters were administered less cefazolin (12% vs 92%; P < .001) and more clindamycin (49% vs 3%; P < .001), vancomycin (35% vs 3%; P < .001), and gentamicin (24% vs 3%; P < .001) compared with those without a reported penicillin allergy. The increased SSI risk was entirely mediated by the patients' receipt of an alternative perioperative antibiotic; between 112 and 124 patients with reported penicillin allergy would need allergy evaluation to prevent 1 SSI.
Conclusions:
Patients with a reported penicillin allergy had a 50% increased odds of SSI, attributable to the receipt of second-line perioperative antibiotics. Clarification of penicillin allergies as part of routine preoperative care may decrease SSI risk.

Obviously this is retrospective, but in my opinion compelling, and we IMO stand to do right by our patients by insisting on squashing the haunting bug of the antibiotic allergy on these patient's charts.

 

[deleted171991]

NNT > 100. Humongous waste of resources.

I think it would be much cheaper to educate anesthesiologists and surgeons not to avoid cephalexin, unless the patient is allergic to... cephalexin. See what @periopdoc posted many times, and the algorithm I posted above.

 

[woopedazz]

Beta-lactam allergic and non-allergic anaphylaxis are nearly always drug-specific and not class specific. Unless there is clear proof of severe anaphylaxis to another beta-lactam or a confirmed systemic allergy of any severity to cephazolin = give cephazolin.