Serum sickness–like reactions to cefaclor: Role of hepatic metabolism and individual susceptibility

Serum sickness-like reaction to D-supplement: a case report

BACKGROUND

Serum Sickness-Like Reaction (SSLR) is an immune response characterized by rash, polyarthralgias, inflammation, and fever. Serum sickness-like reaction is commonly attributed to antibiotics, anticonvulsants, and anti-inflammatory agents.

CASE PRESENTATION

A 16-year-old female with a history of overactive bladder and anemia presented with a diffuse urticarial rash, headaches, joint pain, and swelling for three days. Her medications included oral contraceptive pills, iron, mirabegron, UQora, and a probiotic. Physical examination revealed a diffuse urticarial rash, and her musculoskeletal exam revealed swelling and tenderness in her wrists. She was evaluated by her pediatrician and started on a 7-day course of prednisone, as well as antihistamines. Her CBC, basic metabolic panel, liver function panel, Lyme titers, and urinalysis were all within normal limits. With concern for hypersensitivity reaction to medication, all medications were discontinued. Nine days after symptom onset, the patient was evaluated by an allergist, who confirmed her presentation was consistent with serum sickness-like reaction. Her symptoms resolved, and her medications were re-introduced sequentially over several months. Restarting UQora, however, triggered a recurrence of her symptoms, and it was identified as the culprit medication. Consequently, UQora was permanently discontinued, and the patient has remained symptom-free.

CONCLUSIONS

This case report describes the first documented case of serum sickness-like reaction caused by UQora (active ingredient D-mannose). D-mannose is a monosaccharide, and it is frequently promoted to prevent urinary tract infections. While the clinical features and timeline in this case were typical of serum sickness-like reaction, UQora as the trigger was highly unusual. Clinicians should be aware of the diverse triggers of serum sickness-like reaction and the importance of prompt identification and management to enhance patient safety. Further research is necessary to better understand the potential therapeutic applications of D-mannose, as well as the potential risks and interactions.

A case of pediatric serum sickness like reaction (SSLR) after a 2-month re-exposure to amoxicillin

BACKGROUND

Serum-sickness like reactions (SSLRs) to amoxicillin have been documented in the medical literature. Beta-lactams are important and commonly used medications especially in the pediatric population. Often, SSLRs present within days of and during first exposure/ingestion to the offending agent. We described a unique case of a 4-year-old boy who presented with symptoms of amoxicillin SSLR following his second course of amoxicillin with only 2 months and 10 days between his second and first course.

CASE PRESENTATION

A 4-year-old boy presented to hospital with a pruritic rash on day 7 of a 10-day course of amoxicillin for otitis media accompanied by fever (38.7 degrees Celsius). On day 7 of his second course of amoxicillin, which was separated from his first course by only 2 months and 10 days, his mother noticed erythematous, raised, pruritic lesions with central clearing on his sternum. He presented to the ED with emesis, progression of the rash to his torso, back, legs, and face, hypotension, angioedema, and joint pain. His bloodwork demonstrated a leukocytosis of 18.6 × 109 g/L with neutrophilic predominance and thrombocytosis with a platelet count of 653 × 109 g/L. He was treated with 5 mg oral cetirizine daily and 1 mg/kg oral prednisone which improved his rash and angioedema. He was managed with up to 4 times the usual dose of cetirizine. He was assessed in our outpatient clinic as an outpatient and penicillin skin testing was unremarkable. A diagnosis of a probable SSLR to amoxicillin was made.

CONCLUSION

We report an unusual presentation of SSLR following re-exposure to amoxicillin. Our case highlights that patients with previous asymptomatic exposure to amoxicillin can develop SSLR with repeat exposure. Although it is not uncommon for children to develop amoxicillin SSLRs after previous exposure to the drug, this case is unique because of its short time course of 2 months and 10 days months between drug courses. Penicillins are commonly used in the pediatric population. Therefore, it is important to correctly characterize adverse drug reactions to broaden our understanding of SSLRs, prevent unnecessary avoidance of the triggering agent, and improve patient management.

The role of in vitro testing in pharmacovigilance for ß-lactam-induced serum sickness-like reaction: A pilot study

Background: Current pharmacovigilance (PV) methods for detection of adverse drug reactions (ADRs) fail to capture rare immune-mediated drug hypersensitivity reactions (DHRs) due to their scarcity and the lack of clear diagnostic criteria. Drug-induced serum sickness-like reactions (SSLRs) are rare type of DHRs that occur in susceptible patients 1–3 weeks after exposure to the culprit drug with ß-lactam antibiotics being the most associated drugs. The diagnosis of drug induced SSLR is difficult due to the lack of safe and reliable diagnostic tests for identifying the culprit drug. The lymphocyte toxicity assay (LTA) is an in vitro test used as a diagnostic tool for drug hypersensitivity reactions (DHRs).

Objective: To evaluate the role of the LTA test for diagnosing and capturing SSLR due to ß-lactam antibiotics in a cohort of patients.

Methods: Patients were recruited from patients referred to the Drug Hypersensitivity Clinic at Clinic at London Health Science Centre with suspicion of drug allergy. Twenty patients (10 males and 10 females) were selected to be tested to confirm diagnosis. Demographic data was collected form the patents and blood samples were withdrawn from all patients and from 20 healthy controls. The LTA test was performed on all subjects and data is expressed as percentage increase in cell death compared to control (vehicle without the drug).

Results: In the result of LTA tests performed on samples from the selected 20 patients. There was a significant (p < 0.05) concentration-dependent increase in cell death in cells isolated from patients as compared to cells from healthy controls when incubated with the drug in the presence of phenobarbitone-induced rat liver microsomes.

Conclusion: Giving its safety and good predictive value the LTA test has very strong potential to be a useful diagnostic tool for ß-lactam-induced SSLR. The test procedure is relatively simple and not overly costly. Further studies including other drug classes are needed to evaluate the utility of the LTA test for SSLR due to other drugs.

An EAACI Task Force report on allergy to beta-lactams in children: Clinical entities and diagnostic procedures

Beta-lactam (BL) allergy suspicion is common in children and constitutes a major public health problem, with an impact on patient's health and on medical costs. However, it has been found that most of these reactions are not confirmed by a complete allergic workup. The diagnostic value of the currently available allergy tests has been investigated intensively recently by different groups throughout the world. This has led to major changes in the management of children with a suspected BL allergy. Particularly, it is now well accepted that skin tests can be skipped before the drug provocation test in children with a benign non-immediate reaction to BL. However, there is still a debate on the optimal allergic workup to perform in children with a benign immediate reaction. In addition, management of children with severe cutaneous adverse drug reactions remains difficult. In this review, based on a selection of the most relevant studies found in the literature, we will review and discuss the diagnosis of different forms of BL allergy in children.

Clinical Phenotypes of Severe Cutaneous Drug Hypersensitivity Reactions

Drug hypersensitivity reactions are clinically heterogenous ranging from mild to severe. Most drug hypersensitivity reactions are accompanied by cutaneous manifestations. Fever, mucous membrane involvement, large blisters, facial oedema, pustulosis and visceral involvement are clinical features that lead to suspicion of severe adverse drug reactions. Severe cutaneous adverse drug reactions (SCARs) include Stevens-Johnson syndrome, toxic epidermal necrolysis, drug rash eosinophilia and systemic symptoms, acute generalized exanthematous pustulosis. Serum sickness like reactions, drug induced vasculitis and generalized bullous fixed drug eruptions are less severe clinical entities. SCARs are uncommon but associated with significant morbidity and mortality. Physician should be aware of specific red flags and danger signs to immediately identify these reactions. Immediate drug withdrawal is mandatory. Early diagnosis and appropriate treatment significantly affect the prognosis of the disease. The purpose of our review is to discuss clinical phenotypes of severe cutaneous drug hypersensitivity reactions.

Antibiotic Hypersensitivity Mechanisms

Antibiotics are commonly prescribed to treat a variety of bacterial infections. As with all medications, hypersensitivity reactions may occur and clinicians should be able to recognize them accurately and recommend appropriate management. Antibiotic related hypersensitivity reactions may be one of four different types: Type I reactions, which are IgE mediated and may lead to anaphylaxis; Type II reactions that are antibody-mediated and may result in thrombocytopenia, neutropenia, or hemolytic anemia; Type III reaction that involves an immune complex formation such as vasculitis; and Type IV reactions that consist of four subtypes and typically include a rash of varying level of severity with or without systemic signs and symptoms. Herein, we describe the mechanisms of different types of allergic reactions to commonly prescribed antibiotics and offer recommendations for management. Further, we briefly refer to antibiotic reactions that mimic hypersensitivity reactions but are not immune mediated, such as pseudoallergies and serum sickness-like reactions.

Serum Sickness after Equine Rabies Immunoglobulin in Identical Male Twins: Two Case Reports

We, hereby, report two cases of serum sickness in adult male identical twins who had received equine rabies immunoglobulin as a postexposure rabies treatment after cat scratches. The younger brother developed low-grade fever, polyarthritis, and multiple erythematous maculopapular eruptions, whereas low-grade fever and urticaria-like eruptions were detected in the elder brother. Both patients received a 7-day course of low-dose prednisolone and achieved good responses without recurrent attacks.

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.

Cutaneous drug reactions in children: an update

Cutaneous drug reactions account for a large proportion of adverse drug reactions. Cutaneous drug reactions can be very challenging to diagnose. They can mimic many other skin diseases; this is especially evident during childhood, when viral exanthems are commonplace. Also, if a patient is taking numerous medications, establishing causality to a specific drug can be multifaceted and difficult. The purpose of this review is to highlight an approach to the diagnosis of a suspected cutaneous drug reaction in a child. We have classified different types of drug eruptions by morphology: exanthematous, urticarial, pustular, and bullous. Within each of these groups we have divided them into simple, benign, or non-febrile and complex or febrile reactions. We also include a miscellaneous group to ensure a methodical review.

A review of cutaneous drug eruptions

Cutaneous drug eruptions can range from an asymptomatic rash to a life-threatening emergency. Because of the high frequency, morbidity, and potential mortality associated with drug eruptions, patients with possible drug reactions should promptly be recognized, worked up, and treated. Drug reactions are common in the elderly population due to age-related alterations in metabolism, excretion of medications, and polypharmacy. This review discusses the epidemiology, pathogenesis, clinical presentation, diagnosis, and management of drug eruptions that providers commonly encounter in the care of the geriatric population. An algorithm for an approach to patients with a suspected drug eruption is presented.

Intestinal mucosal permeability of children with cefaclor-associated serum sickness-like reactions

Although the serum sickness-like reaction (SSLR) in children after the administration of cefaclor has long been recognized, the exact mechanism of cefaclor-associated SSLR remains unclear. This study aims to investigate the association between intestinal mucosal permeability and cefaclor-associated SSLR in children. A total of 82 pediatric patients with upper respiratory tract infection following the cefaclor therapy was divided into cefaclor-associated SSLR positive group and negative group based on the presence or absence of SSLR after taking cefaclor, and 30 healthy volunteers served as control group. Urinary lactulose/mannitol (L/M) ratios and serum diamine oxidase (DAO) levels were determined in all cases on days 7, 9, 11, 13, and 15 after oral administration of cefaclor. The children in the control group were given the same measurements after enrollment in this study. From days 7 to 13, the urinary L/M ratio of children with cefaclor SSLR gradually increased and reached to the highest level of 0.38 ± 0.14 on day 13. Compared with the cefaclor-associated SSLR negative group and control group, urinary L/M ratios increased significantly in the cefaclor SSLR positive group on days 7, 9, 11, 13, and 15 after taking cefaclor, and serum levels of DAO following the treatment of cefaclor increased significantly in children with cefaclor SSLR on days 9, 11, 13, and 15. No significant difference in urinary L/M ratios and serum levels of DAO between SSLR negative group and control group through the entire experiment was observed. In conclusion, administration of cefaclor may induce SSLR in children by increasing the intestinal mucosal permeability and/or affecting the integrity of the intestinal mucosa. Determinations of urinary L/M ratios and serum DAO levels may be helpful for observing or predicting the occurrence of SSLR after administration of cefaclor, which will encourage physicians to proceed with extreme caution when prescribing cefaclor for pediatric patients.

Desensitization to antibiotics in children

Drug hypersensitivity reactions can occur to almost all drugs and antibiotics are among the most common cause for this kind of reactions. Drug hypersensitivity may affect any organ or system, and manifestations range widely in clinical severity from mild pruritus to anaphylaxis. In most cases, the suspected drug is avoided in the future. In case of infection, there is usually a safe antibiotic alternative. Nonetheless, in some cases, no alternative treatment exists for optimal therapy. Under these circumstances, desensitization may be performed. Drug desensitization is defined as the induction of a temporary state of tolerance to a drug which can only be maintained by continuous administration of the medication responsible for the hypersensitivity reaction. Desensitization is mainly performed in IgE-mediated reactions. Increasing doses of the implicated drug are administered over a short period of time, until the therapeutic dose is achieved and tolerated. Very few studies confined to children are found in literature. Most of them are case reports. In general, the proposed desensitization schemes are similar to those used in adults differing only in the final dose administered. The purpose of this study is to review desensitization to antibiotics in children presenting and discussing three clinical practical cases of desensitization in this age group.

Educational case series: Mechanisms of drug allergy

Once administered, a drug can activate the immune system by various mechanisms and lead to a large range of clinical manifestations closely related to the type of immune reaction elicited. Administration of the drug can classically result in an immunoglobulin E (IgE)-type sensitization, but can also result in more complex activation of the immune system potentially resulting in severe syndromes, such as the drug-induced hypersensitivity syndrome (DIHS). Although there has been a major increase in our knowledge over the last years, the exact mechanisms of drug allergy are not well understood for most clinical manifestations. A complex interaction between individual characteristics, environmental factors, and the drug itself is usually responsible for adverse reactions to drugs. In this educational review series, we described three cases of drug allergy: first, a child with a typical IgE-mediated drug allergy, second, a child with a non-immediate reaction to penicillin, and in the third patient, we will discuss the drug-induced hypersensitivity syndrome, which is rare but potentially fatal. These cases are correlated to the immune mechanism potentially involved.

Predictive value of the lymphocyte toxicity assay in the diagnosis of drug hypersensitivity syndrome

BACKGROUND

Drug hypersensitivity syndrome (DHS) is a rare but potentially fatal adverse drug reaction that develops in susceptible patients following exposure to certain drugs. Because of the variable clinical picture of DHS and its resemblance to other diseases, the diagnosis of DHS is challenging. The lymphocyte toxicity assay (LTA) is an in vitro test that has been used in the diagnosis of DHS. However, its predictive values are still controversial because of the lack of a 'gold standard' test to measure it against.

OBJECTIVES

To determine the sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of the LTA in the diagnosis of DHS due to different classes of drugs, based on systemic re-exposure as a gold standard, and to evaluate the current clinical utility of the LTA in clinical practice.

METHODS

Potential participants were identified from their medical records and contacted to obtain their consent to participate in the study. One hundred forty-seven patients were recruited and interviewed by telephone to identify events of re-exposure and their consequences. These data were used to determine true positive, false positive, true negative, and false negative results of the test, which were then used to estimate the predictive value of the test.

RESULTS

We identified 26 re-exposure events in 22 patients: 4 were true positives, 17 were true negatives, 1 was a false positive, and 4 were false negatives, as determined by systemic re-exposure. Although the number of identified re-exposures limited the ability to calculate the predictive values, our data provide an estimate of the clinical value of the test for the diagnosis of DHS. The data also highlight the effect of the type of drug involved in the reaction on the predictive value of the test.

CONCLUSION

The LTA is potentially a valuable diagnostic tool for DHS; however, its sensitivity, specificity, NPV, and PPV seem to vary according to the drug involved in the reaction.

Drug allergy: an updated practice parameter

Adverse drug reactions (ADRs) result in major health problems in the United States in both the inpatient and outpatient setting. ADRs are broadly categorized into predictable (type A and unpredictable (type B) reactions. Predictable reactions are usually dose dependent, are related to the known pharmacologic actions of the drug, and occur in otherwise healthy individuals, They are estimated to comprise approximately 80% of all ADRs. Unpredictable are generally dose independent, are unrelated to the pharmacologic actions of the drug, and occur only in susceptible individuals. Unpredictable reactions are subdivided into drug intolerance, drug idiosyncrasy, drug allergy, and pseudoallergic reactions. Both type A and B reactions may be influenced by genetic predisposition of the patient

Identifying genomic and developmental causes of adverse drug reactions in children

Adverse drug reactions are a concern for all clinicians who utilize medications to treat adults and children; however, the frequency of adult and pediatric adverse drug reactions is likely to be under-reported. In this age of genomics and personalized medicine, identifying genetic variation that results in differences in drug biotransformation and response has contributed to significant advances in the utilization of several commonly used medications in adults. In order to better understand the variability of drug response in children however, we must not only consider differences in genotype, but also variation in gene expression during growth and development, namely ontogeny. In this article, recommendations for systematically approaching pharmacogenomic studies in children are discussed, and several examples of studies that investigate the genomic and developmental contribution to adverse drug reactions in children are reviewed.

Drug provocation tests in children: Indications and interpretation

Drug provocation tests in children are always a problematic task. In the present article the most important aspects of this technique are reviewed, including the differences between children and adults; the main mechanisms involved in drug reaction; how to perform the different tests; and when they are indicated.

Cutaneous reactions to drugs in children

Cutaneous eruptions are a commonly reported adverse drug reaction. Cutaneous adverse drug reactions in the pediatric population have a significant impact on patients' current and future care options. A patient's recollection of having a "rash" when they took a medication as a child is a frequent reason for not prescribing a particular treatment. The quick detection and treatment of cutaneous adverse drug reactions, plus identification of the causative agent, are essential for preventing the progression of the reaction, preventing additional exposures, and ensuring the appropriate use of medications for both the current condition and others as the patient ages. The purpose of this review is to discuss a reasonable approach to recognition and initial management of cutaneous adverse drug reactions in children.

Nonimmediate reactions to betalactams

PURPOSE OF REVIEW

Nonimmediate reactions to beta-lactams include several clinical entities, from maculopapular rash to severe reactions such as Steven-Johnson syndrome. Toxic epidermal necrolysis and organ-specific reactions may also occur.

RECENT FINDINGS

Progress has been made in understanding the role of the immunological system in nonimmediate reactions to beta-lactams. Different T-cell subsets recognize beta-lactams after haptenation of serum or cell proteins in the context of major histocompatibility complex. Studies using T-cell lines and clones have shown that a heterogeneous response is generated, with the expression of different cytokine profiles. Betalactams also act on dendritic cells, inducing changes that enable them to interact with naïve lymphocytes, becoming memory T cells. Tissue-activated CD4 and CD8 cells express perforin and other cytotoxic mediators that elicit the lesions. Studies on the clinical course of these entities indicate that cells migrate, establishing a recirculation with homing to the skin and back to the circulation. These cells thus participate not only in skin lesions but probably also in the repair process.

SUMMARY

Understanding the immunological mechanisms involved in nonimmediate reactions to beta-lactams has improved over the last few years, with better definition of the different T-cell subpopulations involved. Experimental studies and monitoring of the response support the implication of different cell subsets.

Recognition and Management of Severe Cutaneous Drug Reactions

Cutaneous drug reactions are among the most common types of adverse drug reactions. This article focuses on the recognition and management of severe cutaneous drug eruptions, including the drug-hypersensitivity syndrome, serum sickness-like reaction, acute generalized exanthematous pustulosis, Stevens-Johnson syndrome, and toxic epidermal necrolysis. Cutaneous reactions are considered severe when they can result in serious skin damage or involve multiple organs. Some of these reactions can cause significant morbidity or death. Each may be confounded by diagnostic difficulties, confusion in ascertaining causality, and treatment challenges.

Adverse events associated with the use of oral cephalosporins/cephems

Historically, oral cephalosporins represent one of the most widely used and safest classes of antimicrobials available. Typical adverse events have included nausea, vomiting, diarrhea, and hypersensitivity reactions. Other more serious events such as pseudomembranous colitis, although infrequent, may occur. The exact type and incidence of adverse events varies depending on the cephalosporin being administered. Differences in adverse event profiles may also vary by age of the patient. Reactions are usually not severe and often do not require termination of therapy. The purpose of this review is to present to healthcare providers the historical safety profile of the most commonly used oral cephalosporins.

Antibacterial agents in pediatrics

Antibiotics are among the most widely prescribed therapeutic agents in children. Several new trends in antibiotic usage for pediatric care have emerged. New mechanisms of antibacterial resistance have required a broader repertoire of antibiotic usage, including new agents directed at multidrug resistance. After promotion of judicious antibiotic use, there has been a decline in the number of pediatric prescriptions for antibiotics. Recent legislation addresses the necessity for pediatric clinical drug trials, ensuring development of further antibacterial agents for use in pediatric patients.

Clinical evaluation and management of drug hypersensitivity

Adverse drug reactions are a major health problem in the inpatient and outpatient clinical setting. Although all of the immune mechanisms of drug reactions are not well characterized, a detailed medication history, knowledge of the signs and symptoms associated with known immune mechanisms, and knowledge of the types of medications typically associated with distinct immune reactions are helpful in implicating the causative drug. Standardized testing for drug reactions is limited, especially for non-IgE-mediated reactions. Management consists of stopping the offending drug, treating the acute reaction, and making a determination concerning future use of the drug.

Adverse skin and joint reactions associated with oral antibiotics in children: the role of cefaclor in serum sickness-like reactions

OBJECTIVE

To review presentations to Princess Margaret Hospital Emergency Department (PMH ED) with adverse joint and skin reactions associated with the use of oral antibiotics, to describe the clinical course of children with cefaclor-related serum sickness-like reactions (cefaclor SSLR) and compare these with cases reported to the Adverse Drug Reactions Advisory Committee (ADRAC).

METHODS

Twelve-month retrospective review of presentations to a tertiary paediatric ED (42,000 visits annually) via an ED computer database search and review of medical charts of children presenting with joint or skin reactions. Telephone interviews were conducted with the caregivers of children with cefaclor SSLR.

RESULTS

Adverse skin or joint reactions occurred in 150 children; 70 after cefaclor alone, 10 after cefaclor in combination with other antibiotics and 70 after other antibiotic courses. SSLR occurred in 44 children; 32 after cefaclor alone, five after cefaclor in combination with other antibiotics and seven after other single antibiotics. In children with cefaclor SSLR, otitis media was the most common indication (59.4%), another 18.8% had viral illnesses. Prolonged sequelae occurred in four children, a situation not previously reported. Sixty reports of paediatric cefaclor SSLR were made to ADRAC during the study period, none originated from PMH ED.

CONCLUSIONS

Cefaclor was associated with 53.3% of oral antibiotic related skin and joint adverse reactions and 84.1% of SSLR. The indications for its use in paediatric illness require careful reconsideration. ADRAC data under-represents the incidence of cefaclor SSLR.

10. Drug allergy

Adverse drug reactions are common, but only 6% to 10% are immunologically mediated. Unlike most adverse drug reactions, allergic drug reactions are unpredictable. Whereas some drug-induced allergic reactions may be easily classified into one of the four Gell and Coombs hypersensitivity categories, many others that appear to have an immunologic component cannot be classified because of our lack of mechanistic information. Theoretically, any drug can induce an immune response. However, some drugs are more likely to elicit clinically relevant immune responses than are others. Drugs in this category include antimicrobial drugs, anticonvulsants, chemotherapeutic agents, heparin, insulin, protamine, and biologic response modifiers. After a drug-disease connection is established, it must be determined whether the reaction was immunologically mediated. Subsequently, confirmatory tests, if available, should be used to determine the allergic status of the patient. If these tests are not available, a graded challenge or desensitization may be considered, depending on the type of clinical reaction previously demonstrated and the need for drug readministration. Education of the patient and primary care physician is an important component of patient management.

Practical aspects of choosing an antibiotic for patients with a reported allergy to an antibiotic

Physicians often must select antibiotics for patients who are reported to have an antibiotic allergy. For penicillins, the sensitivity of penicillin skin testing for predicting serious allergic reactions is excellent. For other beta-lactam antibiotics, penicillin skin testing is useful for excluding the possibility of sensitivity to the beta-lactam ring. For other antibiotics, the patient history remains the most useful tool for determining whether a serious reaction is likely to occur with further drug exposure. The cross-reactivity between penicillins and second- or third-generation cephalosporins (excluding cefamandole) is probably no higher than is the cross-reactivity between penicillins and other classes of antibiotics. When a patient has a suspected immunoglobulin E-mediated antibiotic allergy, desensitization therapy should be considered, if the efficacy of alternate antibiotics is in doubt. For the treatment of serious infections, it is usually possible to safely administer the antibiotic of choice despite a history of possible antibiotic allergy.

Severe serum sickness-like reaction to oral penicillin drugs: three case reports

BACKGROUND

Because the use of heterologous sera has diminished, the incidence of serum sickness has declined. However, serum sickness-like reactions to nonprotein drugs continue to occur.

METHODS

We report three cases of severe serum sickness-like reactions in adults to oral penicillin drugs.

RESULTS

In each patient, significant symptom resolution occurred within 24 hours of starting therapy with oral corticosteroids.

CONCLUSIONS

Serum sickness-like reactions to oral penicillin drugs may be more common than reported in the literature and can be very severe. No specific laboratory finding is universally present or definitively diagnostic. As with classic serum sickness, the diagnosis of serum sickness-like reaction is made clinically. In severe cases such as those presented here with debilitating joint symptoms or life-threatening angioedema, a diagnostic-therapeutic trial of prednisone, 40 to 60 mg at least once daily, is warranted.

Drug allergy diagnosis in humans: possibilities and pitfalls

Due to the potential hazards of drug allergies, an early and reliable diagnosis is crucial. The use of in vivo tests is not recent but, because of the hazards of skin testing in patients with a history of anaphylaxis, they had been abandoned for a while. Recent reevaluations have shown that for some drugs, e.g. antibiotics-reliable skin tests can ensure the diagnosis of drug allergy in up to 70% of cases. Many in vitro tests based on well-defined mechanisms, e.g. the basophil degranulation test have been used for the diagnosis of totally unrelated allergic mechanisms. It is almost impossible to interpret their validity as diagnosis tools. Nevertheless, other tests, e.g. the lymphocyte transformation test which have been evaluated in well-conducted recent studies, seem to have a good predictive value. Their use is still restricted to clinical trials or research studies. A reliable clinical approach as well as a detailed examination of the drug intake remains obligatory to diagnose drug allergy. Available in vivo and in vitro tests are sometimes used to confirm the diagnosis. The sensitivity and specificity of these tests is evaluated in clinical studies. Research to improve the existing tests and to develop new diagnostic tools is still of paramount importance.

Understanding drug allergies

At this time, the incidence of adverse drug reactions can only be estimated because the intensive monitoring and documenting that is required to make this determination does not exist at most hospitals and clinics. Despite these limitations, a meta-analysis of prospective studies has estimated the incidence of serious adverse drug reactions in hospitalized patients to be 6.7% and the incidence of fatal adverse drug reactions to be 0.32%. When evaluating and managing the condition of a patient who has experienced an adverse drug reaction, the physician first obtains an accurate history and performs a careful physical examination to determine whether the reaction was immunologic in nature. Drug reactions that are immunologically mediated (1) require a period of sensitization, (2) occur in a small proportion of the population, (3) are elicited at drug doses far below the therapeutic range, and (4) subside after drug discontinuation in most instances. All possible culprit drugs should be identified, with dosages and dates of administration and discontinuation, and the patient should be asked about any previous drug exposure history. Although immunodiagnostic tests for allergic drug reactions are limited, several tests do exist and may be useful in the identification of drug-specific antibodies, drug-specific T lymphocytes, or mediators from activated cells. If the reaction was not consistent with an IgE-mediated event and if it did not involve serious organ damage, cautious rechallenge may be considered. For those reactions that appear to be IgE-mediated and for which there is no reliable skin test reagent, drug desensitization may be performed by allergists who are trained in this procedure.

Antibacterial agents in pediatrics

From low birth weight infants to adolescents, physiologic and developmental differences underlie the marked differences in pharmacokinetics and pharmacodynamics of antibacterial agents. Certain diseases, such as cystic fibrosis, also can alter these parameters. This article describes the principles of pharmacokinetics and pharmacodynamics that are unique to children and that characterize the clinical application of selected antibacterial agents to infectious diseases in children.

Recognising antibacterial hypersensitivity in children

Adverse reactions to antibacterial agents are not uncommon in children. They are classified as 'immediate' or 'nonimmediate' according to the time interval between drug administration and onset. Immediate reactions occur within 1 hour and are manifested by urticaria and/or angioedema, bronchospasm and anaphylactic shock; immunological reactions are mediated by IgE antibodies. The main nonimmediate reactions (occuring after more than 1 hour) are maculopapular rash, urticaria and serum sickness; T lymphocytes may participate in maculopapular rash. Clinical assessment of such reactions is complex. The patient's history is fundamental; the allergological examination includes in vivo and in vitro tests selected on the basis of the clinical features and the phase of reaction. In the late phase, prick and intradermal tests are sensitive in evaluating beta-lactam allergy. Together with delayed-reading intradermal testing, patch testing seems to be useful in diagnosing maculopapular reactions to systemically administered aminopenicillins. Determination of specific IgE levels is the most common in vitro method for diagnosing immediate reactions. In the acute phase, serum tryptase and urinary N-methylhistamine assays are reliable in diagnosing type I pathogenic mechanisms in immediate reactions. Unfortunately, there are few in vitro tests for evaluating other reactions, and most are not fully validated. In selected cases, provocation tests should be performed.

Drug allergies

Allergic drug reactions are a significant cause of morbidity and mortality. Because it is difficult to identify the culprit drug and the underlying pathophysiologic mechanisms involved in these reactions, a systematic approach should be adopted in the evaluation of drug-allergic patients. Initially, the type of reaction should be determined. It should be realized that not all adverse reactions are allergic in nature. Allergic drug reactions comprise only a small category of adverse reactions in general. Therefore, the physician must determine if the reaction demonstrates features common to immunologic reaction. Subsequently, a detailed history should be obtained and a physical should be performed. Important information includes medication usage, previous drug exposure, current illness, family history of drug allergy and personal history of drug allergy. In managing the drug-allergic patient, the physician may choose to: select an alternative, non-cross-reacting drug if future therapy is needed; premedicate prior to future drug exposure if such regimens have been shown to be effective; or consult an allergist regarding the potential graded challenge or desensitization.