Cephalosporin chemical reactivity and its immunological implications

Are changes in antibiotic prophylaxis recommendations responsible for an increased risk of cefazolin allergy?

BACKGROUND

The first line of prevention of surgical site infection relies on the timely administration of antibiotic prophylaxis. First- and second-generation cephalosporins are the most recommended antibiotics in elective surgery. The incidence of cefazolin allergy has increased worldwide over the years. The sensitization mechanism of cefazolin is currently unknown, and data supporting cross-reactivity between penicillins and cephalosporins are lacking. Sensitization could occur through previous exposure either to cefazolin or to structurally related chemical agents. The objective of this study was to evaluate sensitization agents towards cefazolin.

METHODS

The OpenBabel chemoinformatics toolbox was used to search for similarities between cefazolin and other molecules in an extensive drug database. Using the pholcodine-rocuronium similarity score as a threshold, we selected drugs with the most similar structure to that of cefazolin. Exposure to those drugs and cefazolin was assessed in a cohort of patients with skin test-proven cefazolin allergy at a specialized allergy centre via a self-administered anonymous questionnaire.

RESULTS

Using the pholcodine-rocuronium similarity score as a threshold (score≥0.7), 42 molecules were found to be similar to cefazolin (all cephalosporins). Only 8 were marketed in France. None of the 14 cefazolin-allergic patients who answered the questionnaire (65% female, median age 56 years) reported exposure to any identified antibiotics. In contrast, 11 (78%) had at least one previous surgery requiring cefazolin before the index case.

CONCLUSION

Direct previous cefazolin exposure was identified in 78% of cefazolin-allergic patients. Cefazolin started to take a central place in antibiotic prophylaxis after 2010, when cefamandole usage decreased drastically. Changes in antibiotic prophylaxis over the past 14 years in France could have been the turning point for the increased incidence of cefazolin allergy.

Ω-Loop mutations control the dynamics of the active site by modulating a network of hydrogen bonds in PDC-3 β-lactamase

The expression of antibiotic-inactivating enzymes, such as Pseudomonas-derived cephalosporinase-3 (PDC-3), is a major mechanism of intrinsic resistance in bacteria. To explore the relationships between structural dynamics and altered substrate specificity as a result of amino acid substitutions in PDC-3, innovative computational methods like machine learning driven adaptive bandit molecular dynamics simulations and markov state modeling of the wild-type PDC-3 and nine clinically identified variants were conducted. Our analysis reveals that structural changes in the Ω loop controls the dynamics of the active site. The E219K and Y221A substitutions have the most pronounced effects. The modulation of three key hydrogen bonds K67(sc)-G220(bb), Y150(bb)-A292(bb) and N287(sc)-N314(sc) were found to result in an expansion of the active site, which could have implications for the binding and inactivation of cephalosporins. Overall, the findings highlight the importance of understanding the structural dynamics of PDC-3 in the development of new treatments for antibiotic-resistant infections.

Spectrophotometric studies of low-cost method for determination of ceftriaxone using a novel charge transfer acceptor, N-(2,4-dinitro-1-naphthyl)-p-toluenesulphonamide

Background

This study reports a new, cost-effective and validated method for the determination of ceftriaxone (CFR). The method involved charge transfer (CT) complexation reaction of ceftriaxone (as n-electron donor) and N-(2,4-dinitro-1-naphthyl)-p-toluenesulphonamide {N-(2,4-DN1NL) PTS} as π-electron acceptor to form a complex. Ultraviolet, infrared and 1H NMR spectra of CFR, N-(2,4-DN1NL) PTS and adduct were then studied to predict the site of interaction between the donor and acceptor.

Result

The complex formed had deep golden-yellow colour, having a new absorption band at 440 nm. Molar absorptivity of 1.667 × 105 L M−1 cm−1 was obtained. The complexation reaction was completed at 30 °C optimal temperature within 10 min. Acetonitrile was found to be the best diluting solvent for optimal detector response and the complex was stable (absorbance unchanged) at room temperature for hours. At concentration of 1.708–11.956 µg mL−1, with low limits of detection of 0.143 µg mL−1, Beer’s law was observed. Between-day recovery statistics of CFR from quality control samples were 102.15 ± 0.062 (% RSD = 0.61, n = 12) over three days. The site of interaction of donor and acceptor molecules, as revealed through infrared (IR) and proton nuclear magnetic resonance studies (1H NMR) and the formation of charge transfer complex is through intermolecular hydrogen bonding between the amino group of the donor and the acidic proton of the acceptor. Common tablet excipients, as observed, did not interfere with the analytical method and no significant difference existed between the results of this new method and the high performance liquid chromatographic procedures (p > 0.05) documented in the USP. The new CT procedure described in this paper is not only simple but also fast, accurate and precise. Also, the reactions were carried out at room temperature compared to previously described procedures.

Conclusions

This novel method could therefore be adopted as a fast but cost-effective alternative for the qualitative and quantitative assessment of CFR in its pure and dosage form. It could find usefulness in on-the-spot detection of counterfeit drugs and in field inspections with reliable accurate results that compares with established methods.

β-Lactamase-Responsive Hydrogel Drug Delivery Platform for Bacteria-Triggered Cargo Release

Antibiotic resistance is a growing public health threat that complicates the treatment of infections. β-Lactamase enzymes, which hydrolyze the β-lactam ring present in many common antibiotics, are a major cause of this resistance and are produced by a broad range of bacterial pathogens. Here, we developed hydrogels that degrade specifically in the presence of β-lactamases and β-lactamase-producing bacteria as a platform for bacteria-triggered drug delivery. A maleimide-functionalized β-lactamase-cleavable cephalosporin was used as a crosslinker in the fabrication of hydrogels through end-crosslinked polymerization with multiarm thiol-terminated poly(ethylene glycol) macromers via Michael-type addition. We demonstrated that only hydrogels containing the responsive crosslinker were degraded by β-lactamases and β-lactamase-producing bacteria in vitro and in an ex vivo porcine skin infection model. Fluorescent polystyrene nanoparticles, encapsulated in the hydrogels as model cargo, were released at rates that closely tracked hydrogel wet mass loss, confirming β-lactamase-triggered controlled cargo release. Nonresponsive hydrogels, lacking the β-lactam crosslinker, remained stable in the presence of β-lactamases and β-lactamase-producing bacteria and exhibited no change in mass or nanoparticle release. Furthermore, the responsive hydrogels remained stable in non-β-lactamase enzymes, including collagenases and lipases. These hydrogels have the potential to be used as a bacteria-triggered drug delivery system to control unnecessary exposure to encapsulated antimicrobials, which can provide effective infection treatment without exacerbating resistance.

Intradermal testing increases the accuracy of an immediate-type cefaclor hypersensitivity diagnosis

Background

Hypersensitivity reactions to cefaclor have increased in accordance with its frequent use. However, only limited data are available on the diagnostic value of skin tests for these conditions, particularly intradermal tests (IDTs).

Objective

To evaluate the clinical usefulness of IDT compared to the ImmunoCAP test in patients with cefaclor-induced immediate-type hypersensitivity.

Methods

We conducted a retrospective chart review from January 2010 to June 2020 of adult subjects from 2 tertiary hospitals in Korea with a history of suspected immediate-type hypersensitivity to cefaclor, and who had undergone ImmunoCAP and IDT.

Results

Overall, 131 subjects diagnosed with cefaclor hypersensitivity were included in the analysis. Fifty-nine patients (59/131, 45.04%) were positive in both IDT and ImmunoCAP. Fifty-four (54/131, 41.22%) and 6 (6/131, 4.58%) subjects showed positive results only with IDT or the ImmunoCAP test, respectively. Twelve subjects (12/131, 9.16%) were negative by both tests but reacted positively in a drug provocation test. The frequency of IDT positivity was similar regardless of the severity of reactions. However, positivity of ImmunoCAP was lower in subjects with mild reactions compared to those with anaphylaxis. Regarding the diagnosis of cefaclor hypersensitivity, the overall sensitivity of IDT and ImmunoCAP was 0.863 and 0.496, respectively while the specificity was 1. The combination of IDT and ImmunoCAP further increased this sensitivity to 0.908.

Conclusion

IDT was more sensitive than ImmunoCAP for the diagnosis of cefaclor allergy, regardless of the severity of the hypersensitivity reaction. Therefore, we recommend a combination of IDT and ImmunoCAP for the diagnosis of cefaclor hypersensitivity.

Carbocyanine-Based Fluorescent and Colorimetric Sensor Array for the Discrimination of Medicinal Compounds

Array-based optical sensing is an efficient technique for the determination and discrimination of small organic molecules. This study is aimed at the development of a simple and rapid strategy for obtaining an optical response from a wide range of low-molecular-weight organic compounds. We have suggested a colorimetric and fluorimetric sensing platform based on the combination of two response mechanisms using carbocyanine dyes: aggregation and oxidation. In the first one, the analyte forms ternary aggregates with an oppositely charged surfactant wherein the dye is solubilized in the hydrophobic domains of the surfactant accompanied with fluorescent enhancement. The second mechanism is based on the effect of the analyte on the catalytic reaction rate of dye oxidation with H2O2 in the presence of a metal ion (Cu2+, Pd2+), which entails fluorescence waning and color change. The reaction mixture in a 96-well plate is photographed in visible light (colorimetry) and the near-IR region under red light excitation (fluorimetry). In this proof-of-concept study, we demonstrated the feasibility of discrimination of nine medicinal compounds using principal component analysis: four cephalosporins (ceftriaxone, cefazolin, ceftazidime, cefotaxime), three phenothiazines (promethazine, promazine, chlorpromazine), and two penicillins (benzylpenicillin, ampicillin) in an aqueous solution and in the presence of turkey meat extract. The suggested platform allows simple and rapid recognition of analytes of various nature without using spectral equipment, except for a photo camera.

Diagnostic Approach of Hypersensitivity Reactions to Cefazolin in a Large Prospective Cohort

BACKGROUND

Cefazolin is a common trigger of perioperative anaphylaxis. The diagnostic approach is controversial because the optimal concentration for skin testing is uncertain, drug provocation tests (DPTs) are contraindicated in severe reactions, and in vitro tests are not thoroughly validated.

OBJECTIVE

We aimed to characterize a large number of patients reporting cefazolin allergic reactions and to analyze the diagnostic role of in vivo and in vitro tests.

METHODS

We prospectively evaluated patients with suspicion for allergic reactions to cefazolin by clinical history, skin tests (STs), and, if negative, DPT. In a subgroup of patients, basophil activation test (BAT) and radioallergosorbent test were done before allergologic workup was performed and the final diagnosis was achieved.

RESULTS

We evaluated 184 patients, 76 of whom were confirmed as allergic (41.3%), 90 were nonallergic (48.9%), and 18 were nonconfirmed (9.8%). All patients reporting anaphylactic shock and most reporting anaphylaxis were confirmed to be allergic (P < .001). Forty allergic patients (52.6%) were confirmed by STs, 22 by DPT (28.9%), and 14 by clinical history (18.4%). All subjects manifesting exanthemas and pruritus were nonallergic. The BAT sensitivity was 66.7% when CD63 and CD203c were combined as activation markers. Six of 8 patients with negative STs and positive DPT had a positive BAT.

CONCLUSIONS

Patients allergic to cefazolin often reported severe immediate-type reactions. Skin tests enabled a diagnosis in half of patients when using cefazolin at 20 mg/mL. Unfortunately, DPT could not be performed in all patients owing to reaction severity, which makes BAT a promising diagnostic tool. Further research is needed to clarify the underlying mechanisms, especially in severe reactions.

Classifying cephalosporins: from generation to cross-reactivity

PURPOSE OF REVIEW

To review the most recent literature studying the classifications, immunochemistry, and crossreactivity of allergy reactions to cephalosporins.

RECENT FINDINGS

Over the last five years, research interest has focused on three areas related to cephalosporin allergy: cross-reactivity among cephalosporins and with other beta-lactams; the incidence of adverse reactions in penicillin allergy patients or in reported penicillin allergy labels; and new cephalosporins structures involved in the immunological recognition.

SUMMARY

Meta-analysis of a substantial number of studies shows that cephalosporins are safer than previously thought. Evidence supports two main conclusions in that regard. First, there is a relatively low percentage of cross-reactivity between cephalosporins and other beta-lactams with penicillins in penicillin allergy patients. Second, there is a very low incidence of allergy reactions in nonselected as well as in selected penicillin allergy patients when cephalosporins are used prior to surgical intervention.On the other hand, few structures have been discovered related to the immune mechanism of cephalosporin allergy reactions, and these are far from being ready to use in clinical practice.

Cysteine Hydropersulfide Inactivates β-Lactam Antibiotics with Formation of Ring-Opened Carbothioic S-Acids in Bacteria

Hydrogen sulfide (H₂S) formed during sulfur metabolism in bacteria has been implicated in the development of intrinsic resistance to antibacterial agents. Despite the conversion of H₂S to hydropersulfides greatly enhancing the biochemical properties of H₂S such as antioxidant activity, the effects of hydropersulfides on antibiotic resistance have remained unknown. In this work, we investigated the effects of H₂S alone or together with cystine to form cysteine hydropersulfide (CysSSH) on the activities of antibacterial agents. By using the disc diffusion test, we found that CysSSH treatment effectively inactivated β-lactams of the penicillin class (penicillin G and ampicillin) and the carbapenem class (meropenem). These β-lactams were resistant to treatment with H₂S alone or cystine alone. In contrast, cephalosporin class β-lactams (cefaclor and cefoperazone) and non-β-lactam antibiotics (tetracycline, kanamycin, erythromycin, and ofloxacin) were stable after CysSSH treatment. Chromatographic and mass spectrometric analyses revealed that CysSSH directly reacted with β-lactams to form β-lactam ring-opened carbothioic S-acids (BL-COSH). Furthermore, we demonstrated that certain bacteria (e.g., Escherichia coli and Staphylococcus aureus) efficiently decomposed β-lactam antibiotics to form BL-COSH, which were transported to the extracellular space. These data suggest that CysSSH-mediated β-lactam decomposition may contribute to intrinsic bacterial resistance to β-lactams. BL-COSH may become useful biomarkers for CysSSH-mediated β-lactam resistance and for investigation of potential antibacterial adjuvants that can enhance the antibacterial activity of β-lactams by reducing the hydropersulfides in bacteria.

Risk comparison of beta-lactam-induced anaphylaxis: Therapeutic stratification analysis in a Vietnamese pharmacovigilance database

WHAT IS KNOWN AND OBJECTIVE

There is limited data on the specific risks of anaphylaxis induced by beta-lactam drugs. The aim of this study was to compare the risks of reporting beta-lactam-induced anaphylaxis using the national pharmacovigilance database of Vietnam (NPDV).

METHODS

The multivariate generalised linear regression model was applied for signal generation and comparison of beta-lactams.

RESULTS

Between 2010 and 2016, there were 2,921 reports of anaphylaxis (19.93%) from 14,655 spontaneous reports of beta-lactam use in the NDPV. Anaphylaxis signal generation was also found for the subgroup J01D (cephalosporins and carbapenems) (ROR = 1.27 [1.16-1.39]) and beta-lactamase-sensitive penicillins (ROR = 1.74 [1.27-2.35]). In the third generation cephalosporin subgroup, different risks were identified for the following combinations of beta-lactams: 1) cefotaxime with cefoperazone+sulbactam; 2) cefixime/cefpodoxime/cefdinir with cefoperazone+sulbactam or ceftizoxime/cefoperazone/ceftazidime/ceftriaxone/cefotaxime. For the second generation cephalosporin subgroup, different risks were found for cefotiam compared to cefmetazole, cefaclor, cefamandole and cefuroxime.

WHAT IS NEW AND CONCLUSION

These findings identified and highlighted the different anaphylactic risks caused by various beta-lactams in the main subgroups.

Electrochemistry of Intact Versus Degraded Cephalosporin Antibiotics Facilitated by LC-MS Analysis

The electrochemical detection of cephalosporins is a promising approach for the monitoring of cephalosporin levels in process waters. However, this class of antibiotics, like penicillins, is composed of chemically active molecules and susceptible to hydrolysis and aminolysis of the four membered β-lactam ring present. In order to develop a smart monitoring strategy for cephalosporins, the influence of degradation (hydrolysis and aminolysis) on the electrochemical fingerprint has to be taken into account. Therefore, an investigation was carried out to understand the changes of the voltammetric fingerprints upon acidic and alkaline degradation. Changes in fingerprints were correlated to the degradation pathways through the combination of square wave voltammetry and liquid chromatography quadrupole time-of-flight analysis. The characteristic electrochemical signals of the β-lactam ring disappeared upon hydrolysis. Additional oxidation signals that appeared after degradation were elucidated and linked to different degradation products, and therefore, enrich the voltammetric fingerprints with information of the state of the cephalosporins. The applicability of the electrochemical monitoring system was explored by the analysis of the intact and degraded industrial process waters containing the key intermediate 7-aminodeacetoxycephalosporanic acid (7-ADCA). Clearly, the intact process samples exhibited the expected core signals of 7-ADCA and could be quantified, while the degraded samples only showed the newly formed degradation products.

Penicillin and cephalosporin cross-reactivity: role of side chain and synthetic cefadroxil epitopes

BACKGROUND

Analysis of cross-reactivity is necessary for prescribing safe cephalosporins for penicillin allergic patients. Amoxicillin (AX) is the betalactam most often involved in immediate hypersensitivity reactions (IHRs), and cefadroxil (CX) the most likely cephalosporin to cross-react with AX, since they share the same R1 side chain, unlike cefuroxime (CO), with a structurally different R1. We aimed to analyse cross-reactivity with CX and CO in patients with confirmed IHRs to AX, including sIgE recognition to AX, CX, CO, and novel synthetic determinants of CX.

METHODS

Fifty-four patients with confirmed IHRs to AX based on skin test (ST) and/or drug provocation test (DPT) were included. Serum sIgE to AX and benzylpenicillin was determined by Radioallergosorbent test (RAST). Two potential determinants of CX, involving intact or modified R1 structure, with open betalactam ring, were synthesised and sIgE evaluated by RAST inhibition assay.

RESULTS

Tolerance to CX (Group A) was observed in 64.8% cases and cross-reactivity in 35.2% cases (Group B). Cross-reactivity with CO was only found in 1.8% cases from Group B. ST to CX showed a negative predictive value of 94.6%. RAST inhibition assays showed higher recognition to CX as well as to both synthetic determinants (66% of positive cases) in Group B.

CONCLUSIONS

Cross-reactivity with CX in AX allergic patients is 35%, being ST not enough for prediction. R1, although critical for recognition, is not the unique factor. The synthetic determinants of CX, 1-(HOPhG-Ser-Bu) and 2-(pyrazinone) are promising tools for determining in vitro cross-reactivity to CX in AX allergic patients.

Structural Basis of Reduced Susceptibility to Ceftazidime-Avibactam and Cefiderocol in Enterobacter cloacae Due to AmpC R2 Loop Deletion

Ceftazidime-avibactam and cefiderocol are two of the latest generation β-lactam agents that possess expanded activity against highly drug-resistant bacteria, including carbapenem-resistant Enterobacterales Here, we show that structural changes in AmpC β-lactamases can confer reduced susceptibility to both agents. A multidrug-resistant Enterobacter cloacae clinical strain (Ent385) was found to be resistant to ceftazidime-avibactam and cefiderocol without prior exposure to either agent. The AmpC β-lactamase of Ent385 (AmpCEnt385) contained an alanine-proline deletion at positions 294 and 295 (A294_P295del) in the R2 loop. AmpCEnt385 conferred reduced susceptibility to ceftazidime-avibactam and cefiderocol when cloned into Escherichia coli TOP10. Purified AmpCEnt385 showed increased hydrolysis of ceftazidime and cefiderocol compared to AmpCEnt385Rev, in which the deletion was reverted. Comparisons of crystal structures of AmpCEnt385 and AmpCP99, the canonical AmpC of E. cloacae complex, revealed that the two-residue deletion in AmpCEnt385 induced drastic structural changes of the H-9 and H-10 helices and the R2 loop, which accounted for the increased hydrolysis of ceftazidime and cefiderocol. The potential for a single mutation in ampC to confer reduced susceptibility to both ceftazidime-avibactam and cefiderocol requires close monitoring.

Guideline on diagnostic procedures for suspected hypersensitivity to beta-lactam antibiotics: Guideline of the German Society for Allergology and Clinical Immunology (DGAKI) in collaboration with the German Society of Allergology (AeDA), German Society for Pediatric Allergology and Environmental Medicine (GPA), the German Contact Dermatitis Research Group (DKG), the Austrian Society for Allergology and Immunology (ÖGAI), and the Paul-Ehrlich Society for Chemotherapy (PEG)

This guideline on diagnostic procedures for suspected beta-lactam antibiotic (BLA) hypersensitivity was written by the German and Austrian professional associations for allergology, and the Paul-Ehrlich Society for Chemotherapy in a consensus procedure according to the criteria of the German Association of Scientific Medical Societies. BLA such as penicillins and cephalosporins represent the drug group that most frequently triggers drug allergies. However, the frequency of reports of suspected allergy in patient histories clearly exceeds the number of confirmed cases. The large number of suspected BLA allergies has a significant impact on, e.g., the quality of treatment received by the individual patient and the costs to society as a whole. Allergies to BLA are based on different immunological mechanisms and often manifest as maculopapular exanthema, as well as anaphylaxis; and there are also a number of less frequent special clinical manifestations of drug allergic reactions. All BLA have a beta-lactam ring. BLA are categorized into different classes: penicillins, cephalosporins, carbapenems, monobactams, and beta-lactamase inhibitors with different chemical structures. Knowledge of possible cross-reactivity is of considerable clinical significance. Whereas allergy to the common beta-lactam ring occurs in only a small percentage of all BLA allergic patients, cross-reactivity due to side chain similarities, such as aminopenicillins and aminocephalosporins, and even methoxyimino cephalosporins, are more common. However, the overall picture is complex and its elucidation may require further research. Diagnostic procedures used in BLA allergy are usually made up of four components: patient history, laboratory diagnostics, skin testing (which is particularly important), and drug provocation testing. The diagnostic approach - even in cases where the need to administer a BLA is acute - is guided by patient history and risk - benefit ratio in the individual case. Here again, further studies are required to extend the present state of knowledge. Performing allergy testing for suspected BLA hypersensitivity is urgently recommended not only in the interests of providing the patient with good medical care, but also due to the immense impact of putative BLA allergies on society as a whole.

Immediate cephalosporin allergy

BACKGROUND

Patients who suffer from acute IgE-mediated allergy to a cephalosporin antibiotic are frequently assumed to be at high risk of allergy to other cephalosporins and penicillins.

AIM

To define cross-reactivity patterns in patients with confirmed allergy to a cephalosporin.

METHODS

Subjects presenting with a history of immediate allergy to a cephalosporin-family antibiotic between March 2009 and July 2017 were investigated with specific IgE testing to penicillin, amoxycillin and cefaclor, followed by skin prick testing, intradermal testing and drug provocation testing with a panel of penicillins and cephalosporins.

RESULTS

Out of 564 subjects with a reported beta-lactam allergy, 90 identified a cephalosporin as their index drug. Fifty-five (61.1%) of the 90 subjects tested had a history consistent with an IgE-mediated reaction, of whom 24 (43.6%) were proven to be allergic to their index cephalosporin. Twenty (83.3%) of the 24 were allergic only to their index cephalosporin. Of the four remaining subjects, two were co-sensitised to another beta-lactam with a similar side chain, while the other two had no specific cross-reactivity pattern. Major and minor penicillin determinants were negative for all cephalosporin-allergic individuals.

CONCLUSION

In our cohort, cephalosporin allergy does not appear to be a class effect, with most cases found allergic only to their index cephalosporin. Co-sensitisation to other cephalosporins or penicillins was uncommon, and when it occurred, was usually consistent with side chain cross-reactivity.

Amoxicillin Inactivation by Thiol-Catalyzed Cyclization Reduces Protein Haptenation and Antibacterial Potency

Serum and cellular proteins are targets for the formation of adducts with the β-lactam antibiotic amoxicillin. This process could be important for the development of adverse, and in particular, allergic reactions to this antibiotic. In studies exploring protein haptenation by amoxicillin, we observed that reducing agents influenced the extent of amoxicillin-protein adducts formation. Consequently, we show that several thiol-containing compounds, including dithiothreitol, N-acetyl-L-cysteine, and glutathione, perform a nucleophilic attack on the amoxicillin molecule that is followed by an internal rearrangement leading to amoxicillin diketopiperazine, a known amoxicillin metabolite with residual activity. Increased diketopiperazine conversion is also observed with human serum albumin but not with L-cysteine, which mainly forms the amoxicilloyl amide. The effect of thiols is catalytic and can render complete amoxicillin conversion. Interestingly, this process is dependent on the presence of an amino group in the antibiotic lateral chain, as in amoxicillin and ampicillin. Furthermore, it does not occur for other β-lactam antibiotics, including cefaclor or benzylpenicillin. Biological consequences of thiol-mediated amoxicillin transformation are exemplified by a reduced bacteriostatic action and a lower capacity of thiol-treated amoxicillin to form protein adducts. Finally, modulation of the intracellular redox status through inhibition of glutathione synthesis influenced the extent of amoxicillin adduct formation with cellular proteins. These results open novel perspectives for the understanding of amoxicillin metabolism and actions, including the formation of adducts involved in allergic reactions.

An Update on the Immunological, Metabolic and Genetic Mechanisms in Drug Hypersensitivity Reactions

Drug hypersensitivity reactions (DHRs) represent a major burden on the healthcare system since their diagnostic and management are complex. As they can be influenced by individual genetic background, it is conceivable that the identification of variants in genes potentially involved could be used in genetic testing for the prevention of adverse effects during drug administration. Most genetic studies on severe DHRs have documented HLA alleles as risk factors and some mechanistic models support these associations, which try to shed light on the interaction between drugs and the immune system during lymphocyte presentation. In this sense, drugs are small molecules that behave as haptens, and currently three hypotheses try to explain how they interact with the immune system to induce DHRs: the hapten hypothesis, the direct pharmacological interaction of drugs with immune receptors hypothesis (p-i concept), and the altered self-peptide repertoire hypothesis. The interaction will depend on the nature of the drug and its reactivity, the metabolites generated and the specific HLA alleles. However, there is still a need of a better understanding of the different aspects related to the immunological mechanism, the drug determinants that are finally presented as well as the genetic factors for increasing the risk of suffering DHRs. Most available information on the predictive capacity of genetic testing refers to abacavir hypersensitivity and anticonvulsants-induced severe cutaneous reactions. Better understanding of the underlying mechanisms of DHRs will help us to identify the drugs likely to induce DHRs and to manage patients at risk.

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.

Deciphering the Evolution of Cephalosporin Resistance to Ceftolozane-Tazobactam in Pseudomonas aeruginosa

The presence of β-lactamases (e.g., PDC-3) that have naturally evolved and acquired the ability to break down β-lactam antibiotics (e.g., ceftazidime and ceftolozane) leads to highly resistant and potentially lethal Pseudomonas aeruginosa infections. We show that wild-type PDC-3 β-lactamase forms an acyl enzyme complex with ceftazidime, but it cannot accommodate the structurally similar ceftolozane that has a longer R2 side chain with increased basicity. A single amino acid substitution from a glutamate to a lysine at position 221 in PDC-3 (E221K) causes the tyrosine residue at 223 to adopt a new position poised for efficient hydrolysis of both cephalosporins. The importance of the mechanism of action of the E221K variant, in particular, is underscored by its evolutionary recurrences in multiple bacterial species. Understanding the biochemical and molecular basis for resistance is key to designing effective therapies and developing new β-lactam/β-lactamase inhibitor combinations.

Pseudomonas aeruginosa produces a class C β-lactamase (e.g., PDC-3) that robustly hydrolyzes early generation cephalosporins often at the diffusion limit; therefore, bacteria possessing these β-lactamases are resistant to many β-lactam antibiotics. In response to this significant clinical threat, ceftolozane, a 3′ aminopyrazolium cephalosporin, was developed. Combined with tazobactam, ceftolozane promised to be effective against multidrug-resistant P. aeruginosa. Alarmingly, Ω-loop variants of the PDC β-lactamase (V213A, G216R, E221K, E221G, and Y223H) were identified in ceftolozane/tazobactam-resistant P. aeruginosa clinical isolates. Herein, we demonstrate that the Escherichia coli strain expressing the E221K variant of PDC-3 had the highest minimum inhibitory concentrations (MICs) against a panel of β-lactam antibiotics, including ceftolozane and ceftazidime, a cephalosporin that differs in structure largely in the R2 side chain. The k_cat values of the E221K variant for both substrates were equivalent, whereas the K_m for ceftolozane (341 ± 64 µM) was higher than that for ceftazidime (174 ± 20 µM). Timed mass spectrometry, thermal stability, and equilibrium unfolding studies revealed key mechanistic insights. Enhanced sampling molecular dynamics simulations identified conformational changes in the E221K variant Ω-loop, where a hidden pocket adjacent to the catalytic site opens and stabilizes ceftolozane for efficient hydrolysis. Encouragingly, the diazabicyclooctane β-lactamase inhibitor avibactam restored susceptibility to ceftolozane and ceftazidime in cells producing the E221K variant. In addition, a boronic acid transition state inhibitor, LP-06, lowered the ceftolozane and ceftazidime MICs by 8-fold for the E221K-expressing strain. Understanding these structural changes in evolutionarily selected variants is critical toward designing effective β-lactam/β-lactamase inhibitor therapies for P. aeruginosa infections.

SIAIP position paper: provocation challenge to antibiotics and non-steroidal anti-inflammatory drugs in children

Drug hypersensitivity reactions (DHRs) in childhood are mainly caused by betalactam or non-betalactam antibiotics, and non-steroidal anti-inflammatory drugs (NSAIDs). Laboratory tests for identifying children who are allergic to drugs have low diagnostic accuracy and predictive value. The gold standard to diagnose DHR is represented by the drug provocation test (DPT), that aims of ascertaining the causative role of an allergen and evaluating the tolerance to the suspected drug. Different protocols through the administration of divided increasing doses have been postulated according to the type of drug and the onset of the reaction (immediate or non immediate reactions). DPT protocols differ in doses and time interval between doses. In this position paper, the Italian Pediatric Society for Allergy and Immunology provides a practical guide for provocation test to antibiotics and NSAIDs in children and adolescents.

Suspected Reaction with Cephalosporin May Be a Predictive Factor for β-Lactam Allergy in Children

BACKGROUND

Most children diagnosed with β-lactam allergy based only on history are not truly allergic, and mislabeling leads to use of less effective and more costly alternative broader-spectrum antibiotics, significantly increasing drug resistance.

OBJECTIVE

To determine the frequency and risk factors of confirmed allergy in patients with β-lactam allergy reported by parents or their doctors and evaluate cross-reactivity between β-lactams in children with confirmed allergy.

METHOD

Sixty-seven children with suspected β-lactam allergy were evaluated via history, sIgE measurements, skin tests, and drug provocation tests over a period of 5 years.

RESULTS

β-Lactam allergy was confirmed in 10 (14.9%) patients. Six patients had a positive intradermal test result to one or more of the penicillin skin test materials or ceftriaxone, 4 patients with negative skin test results had positive test results with suspected drugs. Age, gender, time interval between evaluation and the initial reaction, personal history of atopy, parental history of drug allergy, reaction type, and multiple drug allergy history were not significantly different between allergic and tolerant patients. For culprit drugs, there was a significant different between the 2 groups; the rate of confirmed diagnosis was significantly higher for cephalosporins such as ceftriaxone, cefuroxime, and cefprozil (p = 0.03). Three patients with allergy to penicillin tolerated cefuroxime; in 4 patients with selective allergy to ceftriaxone tolerated cephalosporins with a dissimilar side chain (cefadroxil, cefuroxime, cefaclor, and cefdinir).

CONCLUSION

Our study indicates that most patients with a suspected β-lactam allergy tolerated this drug. An appropriate diagnostic allergy workup may prevent the use of less effective and more expensive alternatives.

Angiotensin-converting Enzyme Inhibitor and Other Drug-associated Angioedema

Nonsteroidal antiinflammatory agents, β-lactam antibiotics, non-β lactam antibiotics, and angiotensin-converting enzyme inhibitors are the most common classes of drugs that cause angioedema. Drug-induced angioedema is known to occur via mechanisms mediated by histamine, bradykinin, or leukotriene, and an understanding of these mechanisms is crucial in guiding therapeutic decisions. Nonallergic angioedema occurs in patients with genetic variants that affect metabolism or synthesis of bradykinin, substance P, prostaglandins, or leukotrienes, or when patients are taking drugs that have synergistic mechanisms. The mainstay in treatment of nonallergic drug-induced angioedema is cessation of the offending agents.

A New Pathway for Protein Haptenation by β-Lactams

The covalent binding of β-lactams to proteins upon photochemical activation has been demonstrated by using an integrated approach that combines photochemical, proteomic and computational studies, selecting human serum albumin (HSA) as a target protein and ezetimibe (1) as a probe. The results have revealed a novel protein haptenation pathway for this family of drugs that is an alternative to the known nucleophilic ring opening of β-lactams by the free amino group of lysine residues. Thus, photochemical ring splitting of the β-lactam ring, following a formal retro-Staudinger reaction, gives a highly reactive ketene intermediate that is trapped by the neighbouring lysine residues, leading to an amide adduct. For the investigated 1/HSA system, covalent modification of residues Lys414 and Lys525, which are located in sub-domains IIIA and IIIB, respectively, occurs. The observed photobinding may constitute the key step in the sequence of events leading to photoallergy. Docking and molecular dynamics simulation studies provide an insight into the molecular basis of the selectivity of 1 for these HSA sub-domains and the covalent modification mechanism. Computational studies also reveal positive cooperative binding of sub-domain IIIB that explains the experimentally observed modification of Lys414, which is located in a barely accessible pocket (sub-domain IIIA).

Structural enzymology using X-ray free electron lasers

Mix-and-inject serial crystallography (MISC) is a technique designed to image enzyme catalyzed reactions in which small protein crystals are mixed with a substrate just prior to being probed by an X-ray pulse. This approach offers several advantages over flow cell studies. It provides (i) room temperature structures at near atomic resolution, (ii) time resolution ranging from microseconds to seconds, and (iii) convenient reaction initiation. It outruns radiation damage by using femtosecond X-ray pulses allowing damage and chemistry to be separated. Here, we demonstrate that MISC is feasible at an X-ray free electron laser by studying the reaction of M. tuberculosis ß-lactamase microcrystals with ceftriaxone antibiotic solution. Electron density maps of the apo-ß-lactamase and of the ceftriaxone bound form were obtained at 2.8 Å and 2.4 Å resolution, respectively. These results pave the way to study cyclic and non-cyclic reactions and represent a new field of time-resolved structural dynamics for numerous substrate-triggered biological reactions.

Evolution of diagnostic approaches in betalactam hypersensitivity

INTRODUCTION

Betalactams are the most widely used drugs against infections and the primary cause of antibiotic hypersensitivity reactions. Reaction patterns for different betalactams have been changing in accordance with consumption trends, and vary among countries. As a consequence, in vivo and in vitro tests have had to change with to keep up with new tendencies. Areas covered: This review is focused on advances in betalactam hypersensitivity diagnosis. Changes in in vivo methods have been limited to the inclusion of new haptens. In contrast, major progress has been achieved for in vitro tests since the 1960s, from the first description of immunoassays, the basophil activation test and the lymphocyte transformation test, to the more sophisticated assays developed in last years. Expert commentary: Issues with diagnosis are related to test sensitivity. In vivo tests show higher sensitivity, however they can be risky, especially in severe and life-threatening reactions. Therefore, we believe that in vitro tests should be the preferred method. Current efforts are under way to enhance their sensitivity. Only multidisciplinary approaches involving immunology, proteomics, nanotechnology and chemistry can help us to fully understand conjugate structures and mechanisms involved in hypersensitivity reactions to betalactams, and consequently lead to advances in in vitro methods.

Comparison of the effects of cefazolin and ceftriaxone on canine chondrocyte culture

Cephalosporins (CEFs) are antibiotics frequently used to treat bone infections and septic arthritis. The effects of CEFs on chondrocytes have not been studied until now. Cefazolin (cef1) and ceftriaxone (cef3), first-and third-generation CEFs, were selected to investigate their direct effects on normal and osteoarthritic (OA) primary canine chondrocytes, which were either nonstimulated or stimulated with the pro-inflammatory cytokine IL-1β. In our results, treatment with CEFs increased the negative effects on both conditioned normal and OA chondrocytes, especially when applied to IL-1β-stimulated cells (inflammatory stimulus). CEFs significantly decreased cell viability and induced apoptotic cell death in both normal and OA chondrocytes; moreover, treatment with cef1 caused necrotic cell death in OA chondrocytes. Cef3 treatment could increase s-GAG synthesis in normal cells preincubated with IL-1β, while cef1 had no significant effect. The expression of TNF was clearly downregulated after cef3 treatments, whereas it was upregulated after cef1 treatments. However, cef3 induced stronger downregulation of TIMP1 and the extracellular matrix component genes COL2A1 and ACAN. In conclusion, these results suggest both the cytotoxic effects of CEFs and their adverse effects on chondrogenic marker genes at the transcriptional level, which provide additional insight into the clinical application of cef1 and cef3.

Cefalotin as antimicrobial prophylaxis in patients with known intraoperative anaphylaxis to cefazolin

BACKGROUND

The most common trigger for intraoperative anaphylaxis in Western Australia for the period 2014-5 was an antibiotic used for surgical prophylaxis, cefazolin. In these patients who subsequently present for surgery, alternative cephalosporins are forbidden by current guidelines because of concerns regarding an increased risk of anaphylaxis. However, consideration of the structure-activity relationships relevant to anaphylaxis suggests that cefalotin is a safe alternative because of structural dissimilarities, although there are no pubished clinical data relevant to the perioperative setting.

METHODS

Patients diagnosed with intraoperative anaphylaxis to cefazolin at the Western Australian Anaesthetic Allergy Clinic were tested with intradermal cefalotin and, if negative, subsequently challenged i.v. If tolerated, cefalotin was recommended for subsequent surgery, and subjects were followed up to determine the safety of subsequent intraoperative doses.

RESULTS

Twenty-one subjects diagnosed with immediate hypersensitivity to cephazolin, including 19 subjects with confirmed anaphylaxis, participated. None tested positive to intradermal cefalotin, and all received a graded i.v. challenge to cefalotin without developing signs or symptoms of anaphylaxis. Three subjects subsequently received intraoperative cefalotin 12-139 days later without adverse events.

CONCLUSIONS

A negative intradermal cefalotin skin test has a good negative predictive value in patients who have previously suffered anaphylaxis to cefazolin, allowing the rational and desirable use of this alternative cephalosporin for future surgery and the avoidance of less desirable antimicrobial agents.

Clinical and diagnostic features of perioperative hypersensitivity to cefuroxime

INTRODUCTION

The Danish Anaesthesia Allergy Centre (DAAC) investigated 89 adult patients with suspected perioperative cefuroxime-associated hypersensitivity reactions between 2004 and 2013. The goals were to determine whether the time to index reaction after cefuroxime exposure could be used to implicate cefuroxime as the cause of the reactions and explore different test modalities in diagnosing cefuroxime hypersensitivity.

METHOD

Skin tests, in vitro tests, and titrated provocations were used to determine cefuroxime hypersensitivity. Patients were deemed cefuroxime positive on the basis of at least two positive tests and/or a positive provocation.

RESULTS

One or more tests were positive for cefuroxime in 24 of 89 (27.0%) patients. One was only specific IgE positive and was deemed cefuroxime negative. Twenty-three (25.8%) were deemed cefuroxime positive. There were four specific IgE-, 4 histamine release test-, 13 skin test-, and 14 provocation positive patients. There were eight (34.8%) patients who were only provocation positive. Data on time to index reaction after cefuroxime exposure were available for 80 patients (22 in the positive group and 58 in the negative group), 22 of 22 (100%) of positive patients reacted in <15 min vs. only 38 of 58 (65.5%) of negative patients.

CONCLUSION

All patients with confirmed hypersensitivity to cefuroxime reacted within 15 min of administration, but so did 65.5% of Cefuroxime negative patients, making timing of administration an unreliable predictor of causation in the perioperative setting. Provocations were always positive when carried out in skin test positive patients; however, eight patients had positive provocations only, highlighting the need for provocation in skin test negative patients.

Management of allergy to penicillins and other beta-lactams

The Standards of Care Committee of the British Society for Allergy and Clinical Immunology (BSACI) and an expert panel have prepared this guidance for the management of immediate and non-immediate allergic reactions to penicillins and other beta-lactams. The guideline is intended for UK specialists in both adult and paediatric allergy and for other clinicians practising allergy in secondary and tertiary care. The recommendations are evidence based, but where evidence is lacking, the panel reached consensus. During the development of the guideline, all BSACI members were consulted using a Web-based process and all comments carefully considered. Included in the guideline are epidemiology of allergic reactions to beta-lactams, molecular structure, formulations available in the UK and a description of known beta-lactam antigenic determinants. Sections on the value and limitations of clinical history, skin testing and laboratory investigations for both penicillins and cephalosporins are included. Cross-reactivity between penicillins and cephalosporins is discussed in detail. Recommendations on oral provocation and desensitization procedures have been made. Guidance for beta-lactam allergy in children is given in a separate section. An algorithm to help the clinician in the diagnosis of patients with a history of penicillin allergy has also been included.

Hypersensitivity Pneumonitis Caused by Cephalosporins With Identical R1 Side Chains

Drug-induced hypersensitivity pneumonitis results from interactions between pharmacologic agents and the human immune system. We describe a 54-year-old man with hypersensitivity pneumonitis caused by cephalosporins with identical R1 side chains. The patient, who complained of cough with sputum, was prescribed ceftriaxone and clarithromycin at a local clinic. The following day, he complained of dyspnea, and chest X-ray revealed worsening of inflammation. Upon admission to our hospital, antibiotics were changed to cefepime with levofloxacin, but his pneumonia appeared to progress. Changing antibiotics to meropenem with ciprofloxacin improved his symptoms and radiologic findings. Antibiotics were de-escalated to ceftazidime with levofloxacin, and his condition improved. During later treatment, he was mistakenly prescribed cefotaxime, which led to nausea, vomiting, dyspnea and fever, and indications of pneumonitis on chest X-ray. We performed bronchoalveolar lavage, and the findings included lymphocytosis (23%), eosinophilia (17%), and a low cluster of differentiation (CD) 4 to CD8 ratio (0.1), informing a diagnosis of drug-induced pneumonitis. After a medication change, his symptoms improved and he was discharged. One year later, he was hospitalized for acute respiratory distress syndrome following treatment with ceftriaxone and aminoglycosides for an upper respiratory tract infection. After steroid therapy, he recovered completely. In this patient, hypersensitivity reaction in the lungs was caused by ceftriaxone, cefotaxime, and cefepime, but not by ceftazidime, indicating that the patient's hypersensitivity pneumonitis was to the common R1 side chain of the cephalosporins.

Diagnosis and management of immediate hypersensitivity reactions to cephalosporins

Cephalosporins can cause a range of hypersensitivity reactions, including IgE-mediated, immediate reactions. Cephalosporin allergy has been reported with use of a specific cephalosporin, as a cross-reaction between different cephalosporins or as a cross-reaction to other β-lactam antibiotics. Unlike penicillins, the exact allergenic determinants of cephalosporins are less well understood and thus, standardized diagnostic skin testing is not available. Nevertheless, skin testing with diluted solutions of cephalosporins can be valuable in confirming IgE-mediated hypersensitivity reactions. In vitro tests are in development using recent technological advances and can be used as complementary tests. However, they are not commonly used because of their reduced sensitivity and limited availability. In selected cases of inconclusive results in both skin tests and IgE assays, a graded challenge or induction of drug tolerance with the implicated cephalosporin should be performed.

Antibiotic allergy

Although allergy to β-lactam and non-β-lactam antibiotics is commonly claimed, true allergy to these drugs is often absent. Reactions to antibiotics can be classified according to the interval between the last administration of the drug and the onset of symptoms, but except for immediate reactions occurring within an hour of exposure, which are almost always either IgE-mediated or due to direct stimulation of mast cells, reactions occurring later than 1 hour probably have multiple mechanisms, including being IgE-mediated or involving cell-mediated reactions. The latter are likely caused by drug-specific T lymphocytes. The diagnosis of antibiotic allergy can be difficult.

Hypersensitivity reactions to beta-lactams

Beta-lactam antibiotics (BLs) are the most frequent cause of hypersensitivity reactions mediated by specific immunological mechanisms, with two main types, IgE reactions or T-cell-dependent responses. From a practical point of view, these reactions can be classified into immediate, for those appearing within 1 h after drug intake, and non-immediate, for those appearing at least 1 h after and usually within 24 h of BL administration. The clinical symptoms differ according to this classification. Urticaria and anaphylaxis are the most frequently recorded symptoms in immediate reactions and maculopapular exanthema and delayed urticaria in non-immediate reactions. Although the exact diagnostic approach differs depending on the underlying mechanism, it is based on the performance of skin testing, laboratory tests, and drug provocation tests.T cells are a key factor in all types of hypersensitivity reactions to BLs, regulating both IgE production or acting as effector cells, with a different profile of cytokine production. A Th1 pattern is observed in both CD4(+) and CD8(+) peripheral T cells in non-immediate reactions, whereas a Th2 pattern is expressed in CD4(+) T cells in immediate reactions.

T cell responses to drugs and drug metabolites

Understanding the chemical mechanisms by which drugs and drug metabolites interact with cells of the immune system is pivotal to our knowledge of drug hypersensitivity as a whole.In this chapter, we will discuss the currently accepted mechanisms where there is scientific and clinical evidence to support the ways in which drugs and their metabolites interact with T cells. We will also discuss bioanalytical platforms, such as mass spectrometry, and in vitro test assays such as the lymphocyte transformation test that can be used to study drug hypersensitivity; the combination of such techniques can be used to relate the chemistry of drug antigen formation to immune function. Ab initio T cell priming assays are also discussed with respect to predicting the potential of a drug to cause hypersensitivity reactions in humans in relation to the chemistry of the drug and its ability to form haptens, antigens and immunogens in patients.

Drug allergy: causes and desensitization

Allergic drug reactions occur when a drug, usually a low molecular weight molecule, has the ability to stimulate an immune response. This can be done in one of two ways. The first is by binding covalently to a self-protein, to produce a haptenated molecule that can be processed and presented to the adaptive immune system to induce an immune response. Sometimes the drug itself cannot do this but a reactive breakdown product of the drug is able to bind covalently to the requisite self-protein or peptide. The second way in which drugs can stimulate an immune response is by binding non-covalently to antigen presenting or antigen recognition molecules such as the major histocompatibility complex (MHC) or the T cell receptor. This is known as the p-I or pharmacological interaction hypothesis. The drug binding in this situation is reversible and stimulation of the response may occur on first exposure, not requiring previous sensitization. There is probably a dependence on the presence of certain MHC alleles and T cell receptor structures for this type of reaction to occur.

IgE Sensitization to Cephalosporins in Health Care Workers

Purpose

Cephalosporins can induce occupational allergies, such as asthma, urticaria, and anaphylaxis. We investigated the prevalence and risk factors of sensitization to cephalosporin.

Methods

A total of 161 health care workers (HCW), including 138 nurses and 23 pharmacists, and 86 unexposed non-atopic healthy controls were recruited from a single tertiary hospital and the general population. A questionnaire regarding work-related symptoms was administered along with skin prick tests (SPT) to the three most commonly used cephalosporins (cefotiam, ceftriaxone, and ceftizoxime). Serum specific IgE antibodies to conjugates of the three cephalosporins and human serum albumin (HSA) were measured by enzyme-linked immunosorbent assay (ELISA). Binding specificities were confirmed by ELISA inhibition tests.

Results

The prevalence of work-related symptoms in association with cephalosporins was 17.4%. The sensitization rate to any cephalosporin was 3.1% by SPT. Sensitization rates determined by measurement of serum specific IgE antibodies were 17.4% for any cephalosporin, 10.4% for cefotiam, 6.8% for ceftriaxone, and 3.7% for ceftizoxime. A personal history of any antibiotic allergy was a risk factor for work-related symptoms (OR, 24.93; 95% CI, 2.61-238), but not for the presence of serum specific IgE antibodies to cephalosporins (OR, 0.9; 95% CI, 0.18-4.53). A personal history of atopic dermatitis was a risk factor for the presence of serum specific IgE antibodies to cefotiam-HSA conjugate (OR, 6.30; 95% CI, 1.23-32.3).

Conclusions

A high cephalosporin sensitization rate (17.4%) was detected by ELISA in HCW exposed to cephalosporins. Monitoring of serum specific IgEs to cephalosporin-HSA conjugates will be useful for detecting sensitized subjects.

A statement on cefazolin immediate hypersensitivity: data from a large database, and focus on the cross-reactivities

BACKGROUND

More perioperative cefazolin use has resulted in an increased risk of cefazolin-associated reactions.

OBJECTIVE

The aim of this article is to study immediate reactions to cefazolin and attempt to determine possible allergic cross-reactivity with other ß-lactams using data from the Drug Allergy and Hypersensitivity Database (DAHD).

METHODS

All 25 cefazolin-associated reactions in the DAHD were reviewed. The cases identified were then investigated according to the European Network for Drug Allergy (ENDA) recommendations by skin testing and challenges.

RESULTS

A total of 10 individuals with proven IgE-mediated cefazolin hypersensitivity were identified between January 1999 and July 2009. All the index reactions were compatible with an acute IgE-mediated process, six with anaphylaxis, two with systemic allergic reactions without hypotension, and two with urticaria/angioedema. Cefazolin skin tests were positive in seven individuals and cefazolin challenges were positive in three more individuals. In the eight cefazolin allergic patients who had challenges with other ß-lactams, there was no positive reaction noted.

CONCLUSION AND CLINICAL RELEVANCE

In this cohort of patients with IgE-mediated reactions to cefazolin, a majority tolerated amoxicillin and several patients tolerated other cephalosporins. This implies that the R1 side-chain may play an essential role in IgE-mediated reactions to cefazolin. No clear rule to predict cross-reactivity with other ß-lactams could be determined. More research on IgE-mediated hypersensitivity to cefazolin and other cephalosporins is needed.