Tolerability of cefazolin after immune-mediated hypersensitivity reactions to nafcillin in the outpatient setting

Management of Penicillin Allergy in the Perioperative Setting

The selection of perioperative antibiotic prophylaxis is challenging in patients with a history of penicillin allergy; as such, we present a literature review exploring current best practices and the associated supporting evidence, as well as areas for future research. Guidelines recommend the use of alternative agents in patients with an IgE-mediated hypersensitivity reaction, but those alternative agents are associated with worse outcomes, including an increased risk of surgical site infection, and higher cost. More recent data suggest that the risk of cross-reactivity between penicillins and cephalosporins, particularly cefazolin, is extremely low, and that cefazolin can be used safely in most penicillin-allergic patients. Studies have therefore explored how best to implement first-line cefazolin use in patients with a penicillin allergy label. A variety of interventions, including preoperative allergy de-labeling with incorporation of penicillin skin testing, use of patient risk-stratification questionnaires, and utilization of clinician algorithms to guide antibiotic selection intraoperatively, have all been shown to significantly increase cefazolin utilization without a corresponding increase in adverse events. Further studies are needed to clarify the most effective interventions and implementation strategies, as well as to evaluate whether patients with severe delayed hypersensitivity reactions to penicillin should continue to be excluded from receipt of other beta-lactams.

Penicillin Allergy Impact and Management

There is international evidence that penicillin allergies are associated with inferior prescribing and patient outcomes. A host of tools now exist from assessment (risk assessment tools, clinical decision rules) to delabeling (the removal of a beta-lactam allergy via testing or medical reconciliation) to reduce the impact of these "labels" in the hospital and community setting, as a primary antimicrobial stewardship intervention.

Tolerability of Cefazolin in Nafcillin-Intolerant Patients for the Treatment of Methicillin-Susceptible Staphylococcus aureus Infections

BACKGROUND

Non-IgE-mediated hypersensitivity reactions (HSRs) to nafcillin are commonly reported, but scarce data are available to guide appropriate antibiotic change following these reactions. While cefazolin is an attractive therapeutic alternative in methicillin-susceptible Staphylococcus aureus (MSSA) infections when patients experience an HSR to nafcillin, more data are needed to evaluate the tolerability of cefazolin after switching from nafcillin. The purpose of this study was to describe the tolerability of cefazolin in patients who develop a suspected non-IgE-mediated HSR to nafcillin.

METHODS

This was a retrospective, descriptive case series of patients who received nafcillin for an MSSA infection, experienced a suspected non-IgE-mediated HSR, and were switched to cefazolin between October 2015 and November 2019 at a single academic medical center. The primary objective was to identify the percentage of patients who completed cefazolin after experiencing a suspected non-IgE-mediated HSR to nafcillin.

RESULTS

There were 80 patients with 87 pre-specified non-IgE-mediated HSRs during the study period. Seventy-one (89%) patients completed cefazolin, with 53 (75%) of these patients completing at least 2 weeks of therapy. One patient was ultimately switched from cefazolin to daptomycin due to concern for treatment failure. Eight patients (10%) did not tolerate cefazolin after switching from nafcillin. Of these, 3 patients experienced an unrelated HSR, while 5 patients experienced the same non-IgE-mediated HSR that was attributed to nafcillin and discontinued cefazolin within 7 days. The most common HSR cited was immune-mediated nephritis; however, the majority were clinically presumed but did not meet objective diagnostic criteria.

CONCLUSIONS

Treatment with cefazolin after experiencing a suspected non-IgE-mediated HSR to nafcillin appears to be safe, even for patients requiring a prolonged duration of cefazolin.

β-Lactam Allergy and Cross-Reactivity: A Clinician's Guide to Selecting an Alternative Antibiotic

β-Lactams which include penicillins, cephalosporins, carbapenems, and monobactams are the most common antibiotic classes reported to cause allergic reactions to drugs. This review is mainly about published studies assessing the cross-reactivity among β-lactams in penicillin- or cephalosporin-allergic subjects by carrying out diagnostic tests with alternative β-lactams and, if appropriate, graded challenges. Several studies demonstrated that cross-reactivity connected with the β-lactam ring, causing positive responses to allergy tests with all β-lactams, is infrequent in subjects with an IgE-mediated allergy and anecdotal in those with a T-cell-mediated allergy. Identities or similarities of β-lactam side-chain structures are mainly responsible for cross-reactivity among these antibiotics. For example, in aminopenicillin-allergic subjects, cross-reactivity with aminocephalosporins could possibly be over 30%. On the other hand, in a few prospective studies of penicillin-allergic individuals, less than 1% of cases show a cross-reactivity between penicillins and both aztreonam and carbapenems. Particular patterns of allergy-test positivity observed in some studies that assessed cross-reactivity among β-lactams seem to indicate that prior exposures may be responsible for coexisting sensitivities. Therefore, pre-treatment skin tests with the related β-lactams are suggested before administering them via graded challenges to β-lactam-allergic patients who need alternative β-lactams.

Multiple drug allergies: Recommendations for perioperative management

Life-threatening hypersensitivity reactions are more likely to occur in patients with a history of allergy, atopy, or asthma. Hence, in a patient who presented with a history of multiple drug allergies (MDA), an allergological assessment should be performed prior to surgical procedure. Drug allergies, being one of the causes of catastrophic events occurring in the perioperative period, are of major concern to anesthesiologists. Neuromuscular blocking agents are regularly used during anesthesia and are one of the most common causes of perioperative anaphylaxis. They are estimated to be responsible for 50%-70% of perioperative hypersensitivity reactions. Antibiotics and latex represent the next two groups of drug allergy. Allergic reactions to propofol are rare with an incidence of 1:60,000 exposures. Although intraoperative drug anaphylaxis is rare, it contributes to 4.3% of deaths occurring during general anesthesia. These recommendations discuss pathophysiology of MDA, preoperative evaluation, and anesthesia considerations as well as the prevention and management of allergic reactions in anesthetized patients with a history of MDA.

Therapy of Staphylococcus aureus bacteremia: Evidences and challenges

Staphylococcus aureus bacteremia (SAB) is still a daily challenge for clinicians. Despite all efforts, the associated mortality and morbidity has not significantly improved in the last 20 years. The available evidence suggests that adherence to some quality-of-care indicators with regard to clinical management is important in improving the outcome of patients, but it is lower than desired in many hospitals; as such, management of patients with SAB by infectious diseases specialists has been demonstrated to contribute in the reduction of the mortality rate of these patients. In this article, the most relevant clinical studies published over the last few years evaluating the efficacy and safety of alternative drugs for the treatment of SAB are reviewed. However, classic drugs are still used in a high proportion of patients because the promising results obtained from in vivo and in vivo studies with these alternative drugs have not translated as frequently as expected into evident superiority in clinical studies. Nevertheless, some data suggest that certain alternatives may offer advantages in specific situations. Overall, an individualised and expert approach is needed in order to decide the best treatment according to the source, severity, complications, patients' features and microbiological data.

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) Syndrome Identified in the Electronic Health Record Allergy Module

BACKGROUND

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare but severe hypersensitivity reaction that remains poorly characterized in the United States.

OBJECTIVE

To identify and describe DRESS syndrome cases in an integrated health care system using electronic health record (EHR) allergy module free-text searches.

METHODS

We identified DRESS syndrome cases with rash, absolute eosinophil count of 500/L or more, organ involvement, and a European Registry of Severe Cutaneous Adverse Reactions to Drugs and Collection of Biological Samples score of 2 or more by reviewing those patients from 1980 to 2016 whose EHR allergic reaction matched DRESS-related key words. Liver injury required alanine aminotransferase level of 100 U/L or more, and renal injury required creatinine increase by 0.5 mg/dL (or 50%) or more. Patient and DRESS characteristics were described, resource use was determined, and cost was estimated.

RESULTS

Among 3,162,562 patients with 3,319,387 million allergy entries, 538 reactions matched key words, and 69 were DRESS syndrome cases (prevalence 2.18 per 100,000). Patients with DRESS had liver (42%) or renal (42%) injury; 11 (16%) had both liver and renal injury. Primary drug culprits were antibiotics (74%) (vancomycin [39%], β-lactams [23%], fluoroquinolones [4%], tetracyclines [4%], and sulfonamides [3%]) and anticonvulsants (20%). Of 65 (94%) hospitalized patients with DRESS, 43 (66%) were hospitalized for DRESS syndrome management with median length of stay of 9 days (interquartile range, 6-17 days) and cost approximately $17,101 per patient.

CONCLUSIONS

Using free-text search of the EHR allergy module identified a large US DRESS syndrome cohort. DRESS prevalence was 2.18 per 100,000 patients. Both liver and kidney injury were frequent, and vancomycin was the most common drug culprit. DRESS cases were morbid and resource-intensive.

Cephalosporin Allergy: Current Understanding and Future Challenges

Cephalosporins are commonly used antibiotics both in hospitalized patients and in outpatients. Hypersensitivity reactions to cephalosporins are becoming increasingly common with a wide range of immunopathologic mechanisms. Cephalosporins are one of the leading causes for perioperative anaphylaxis and severe cutaneous adverse reactions. Patients allergic to cephalosporins tend to tolerate cephalosporins with disparate R1 side chains but may react to other beta-lactams with common R1 side chains. Skin testing for cephalosporins has not been well validated but appears to have a good negative predictive value for cephalosporins with disparate R1 side chains. In vitro tests including basophil activation tests have lower sensitivity when compared with skin testing. Rapid drug desensitization procedures are safe and effective and have been used successfully for immediate and some nonimmediate cephalosporin reactions. Many gaps in knowledge still exist regarding cephalosporin hypersensitivity.

Prevalence of a Cefazolin Inoculum Effect Associated with blaZ Gene Types among Methicillin-Susceptible Staphylococcus aureus Isolates from Four Major Medical Centers in Chicago

The efficacy of cefazolin with high-inoculum methicillin-susceptible Staphylococcus aureus (MSSA) infections remains in question due to therapeutic failure inferred as being due to an inoculum effect (InE). This study investigated the local prevalence of a cefazolin InE (CInE) and its association with staphylococcal blaZ gene types among MSSA isolates in the Chicago area. Four medical centers in Chicago, IL, contributed MSSA isolates. Cefazolin MICs (C-MIC) were determined at 24 h by the broth microdilution method using a standard inoculum (SI; 5 × 10⁵ CFU/ml) and a high inoculum (HI; 5 × 10⁷ CFU/ml). The CInE was defined as (i) a ≥4-fold increase in C-MIC between SI and HI and/or (ii) a pronounced CInE, i.e., a nonsusceptible C-MIC of ≥16 μg/ml at HI. PCR was used to amplify the blaZ gene, followed by agarose gel electrophoresis and sequencing to determine the gene type. Approximately 269 MSSA isolates were included. All but one isolate were susceptible to cefazolin at SI, and 97% remained susceptible at HI. A total of 196 isolates (73%) were blaZ positive, with the blaZ types led by gene type C (40%). CInE was seen in 45 blaZ-positive isolates (23%), with 44 (22%) presenting a ≥4-fold increase in C-MIC (SI to HI) and 5 (3%) a pronounced CInE. Four of the five met both definitions of CInE, two of which expressed the type A gene. The prevalence of a pronounced CInE associated with the type A blaZ gene from MSSA isolates in Chicago is low. Our predilection for cefazolin use, even early in the management of hospitalized MSSA infections, is tenable.

Successful treatment of multidrug-resistant Pseudomonas aeruginosa pubic symphysis osteomyelitis with ceftolozane/tazobactam

New antibiotic options are needed for the treatment of multidrug-resistant (MDR) Pseudomonas infections. We present a case of a man aged 64 years with a bladder fistula due to radiation, ultimately causing osteomyelitis of the pubic symphysis. Repeated antibiotic courses, without correcting the fistula, resulted in infection with MDR Pseudomonas aeruginosa. He was successfully treated for his osteomyelitis through cystectomy, aggressive debridement and a prolonged course of antimicrobials directed at the MDR Pseudomonas isolate.

Significant publications on infectious diseases pharmacotherapy in 2015

PURPOSE

The most important articles on infectious diseases (ID) pharmacotherapy published in the peer-reviewed literature in 2015, as nominated and selected by panels of pharmacists and others with ID expertise, are summarized.

SUMMARY

Members of the Houston Infectious Diseases Network were asked to nominate articles published in prominent peer-reviewed journals in 2015 that were thought to have a major impact in the field of ID pharmacotherapy. A list of 55 nominated articles on general ID-related topics and 10 articles specifically related to human immunodeficiency virus (HIV) infection or acquired immunodeficiency syndrome (AIDS) was compiled. In a national online survey, members of the Society of Infectious Diseases Pharmacists (SIDP) were asked to select from the list 10 general ID articles believed to have made a significant contribution to the field of ID pharmacotherapy and 1 article contributing to HIV/AIDS pharmacotherapy. Of the 361 SIDP members surveyed, 153 (42%) and 76 (21%) participated in the selection of general ID-related articles and HIV/AIDS-related articles, respectively. The 11 highest-ranked publications (10 general ID-related articles and 1 HIV/AIDS-related article) are summarized here.

CONCLUSION

With the growing number of significant ID-related publications each year, it can be challenging to stay current with the literature. This review of important ID pharmacotherapy publications in 2015 may be helpful in identifying key articles and lessening this burden.

Impact of a clinical guideline for prescribing antibiotics to inpatients reporting penicillin or cephalosporin allergy

BACKGROUND

Self-reported penicillin allergy infrequently reflects an inability to tolerate penicillins. Inpatients reporting penicillin allergy receive alternative antibiotics that might be broader spectrum, more toxic, or less effective.

OBJECTIVE

To develop and assess a clinical guideline for the general inpatient provider that directs taking a history and prescribing antibiotics for patients with penicillin or cephalosporin allergy.

METHODS

A guideline was implemented to assist providers with assessing allergy history and prescribing antibiotics for patients with reported penicillin or cephalosporin allergy. The guideline used a standard 2-step graded challenge or test dose. A quasi-experimental study was performed to assess safety, feasibility, and impact on antibiotic use by comparing treatment 21 months before guideline implementation with 12 months after guideline implementation.

RESULTS

Significantly more test doses to β-lactam antibiotics were performed monthly after vs before guideline implementation (median 14.5, interquartile range 13-16.25, vs 2, interquartile range 1-3.25, P < .001). Seven adverse drug reactions occurred during guideline-driven test doses, with no significant difference in rate (3.9% vs 6.1%, P = .44) or severity (P > .5) between periods. Guideline-driven test doses decreased alternative antimicrobial therapy after the test dose, including vancomycin (68.3% vs 37.2%, P < .001), aztreonam (11.5% vs 0.5%, P < .001), aminoglycosides (6.0% vs 1.1%, P = .004), and fluoro quinolones (15.3% vs 3.3%, P < .001).

CONCLUSION

The implementation of an inpatient antibiotic prescribing guideline for patients with penicillin or cephalosporin allergy was associated with an almost 7-fold increase in the number of test doses to β-lactams without increased adverse drug reactions. Patients assessed with guideline-driven test doses were observed to have significantly decreased alternative antibiotic exposure.

Comparative outcomes of β-lactam antibiotics in outpatient parenteral antibiotic therapy: treatment success, readmissions and antibiotic switches

OBJECTIVES

β-Lactam antibiotics are commonly used in outpatient parenteral antimicrobial therapy (OPAT), but data regarding outcomes of long-term therapy are limited. The purpose of this study was to compare treatment success, readmission and antibiotic switch rates in patients treated with β-lactam antibiotics as OPAT.

METHODS

We carried out a retrospective review of all patients, discharged from Tufts Medical Center with cefazolin, ceftriaxone, ertapenem or oxacillin, between January 2009 and June 2013. A competing risks analysis was used to compare the cumulative incidence of first occurrence of treatment success, antibiotic switch and 30 day readmission for each drug.

RESULTS

Four hundred patients were identified (cefazolin n = 38, ceftriaxone n = 104, ertapenem n = 128 and oxacillin n = 130). Baseline demographics were similar. Treatment success rates were higher for ceftriaxone and ertapenem (cefazolin 61%, ceftriaxone 81%, ertapenem 73% and oxacillin 58%; P < 0.001). Thirty-day all-cause readmissions were similar (cefazolin 21%, ceftriaxone 14%, ertapenem 20% and oxacillin 15%; P = 0.46). In 400 OPAT courses, 37 out of 50 antibiotic switches were accomplished without readmission. Adverse drug events (ADEs) were the most common reason for outpatient antibiotic switches (31/37, 84%). The ADE rate was higher for the oxacillin group (cefazolin 2.0 versus ceftriaxone 1.5 versus ertapenem 2.9 versus oxacillin 8.4 per 1000 OPAT days; P < 0.001).

CONCLUSIONS

OPAT with β-lactam antibiotics is effective, but antibiotic switches for adverse events were more frequent with oxacillin use. Clinicians should be cognizant of the risk of readmissions and ADEs in OPAT patients, as the value of OPAT lies in reducing patient morbidity and readmissions by managing ADEs and preventing clinical failures.

Comparative evaluation of the tolerability of cefazolin and nafcillin for treatment of methicillin-susceptible Staphylococcus aureus infections in the outpatient setting

BACKGROUND

Nafcillin and cefazolin are considered first-line therapy for most infections with methicillin-susceptible Staphylococcus aureus (MSSA), and recent studies have suggested similar clinical efficacy. Limited data are available on the comparative tolerability of these agents.

METHODS

In this retrospective cohort analysis of patients treated with either nafcillin or cefazolin for MSSA infection in the outpatient parenteral antimicrobial therapy clinic at Massachusetts General Hospital from 2007 to 2011, the frequency of premature antimicrobial discontinuation (PAD) and drug-emergent events (DEEs) was calculated.

RESULTS

Three hundred sixty-six and 119 patients were treated with nafcillin or cefazolin, respectively. The median anticipated duration of therapy was comparable at 28 (interquartile range [IQR], 16-37) and 29 (IQR, 24-39) days, respectively, for those treated with nafcillin and cefazolin. Fewer patients completed the prespecified treatment course with nafcillin than with cefazolin (PAD rate, 33.8% vs 6.7%; P < .0001). The hazard ratio for PAD in the nafcillin vs cefazolin groups was 2.81 (95% confidence interval [CI], 1.26-3.68). More patients in the nafcillin group developed rash (13.9% vs 4.2%; P = .002), renal dysfunction (11.4% vs 3.3%; P = .006), and liver function abnormalities (8.1% vs 1.6%; P = .01). Overall rates of DEEs per 1000 patient-days were 16.9 (95% CI, 10.4-27.3) and 4.8 (95% CI, 1.1-10.2), respectively. In 9 cases of nafcillin discontinuation, treatment was changed to cefazolin; all 9 completed treatment with no further observed DEEs.

CONCLUSIONS

Nafcillin treatment was associated with higher rates of both PAD as well as DEEs compared with cefazolin treatment. This difference in tolerability, in addition to efficacy and cost, should be considered when decisions for outpatient parenteral MSSA treatment are made.