A new assay for the detection of Loxosceles species (brown recluse) spider venom

Fatal Viscerocutaneous Brown Recluse Envenomation With Orbital Compartment Syndrome

Loxosceles is an arachnid genus comprising several species in the United States, popularly known as brown recluse spiders. The venom is cytotoxic, complex, and has a mixture of many proteins, some of which function as proteases. Envenomation can cause necrotic skin lesions that may become extensive and take many months to heal. Even more rarely, venom may cause systemic effects, leading to widespread hemolysis, coagulopathy, and death. These symptoms typically occur rapidly within 24-48 hours following the bite. We describe a rare case of a 44-year-old male with fatal systemic loxoscelism with orbital compartment syndrome requiring emergent lateral canthotomy and cantholysis.

A Brief Overview of the Toxic Sphingomyelinase Ds of Brown Recluse Spider Venom and Other Organisms and Simple Methods To Detect Production of Its Signature Cyclic Ceramide Phosphate

A special category of phospholipase D (PLD) in the venom of the brown recluse spider (Loxosceles reclusa) and several other sicariid spiders accounts for the dermonecrosis and many of the other clinical symptoms of envenomation. Related proteins are produced by other organisms, including fungi and bacteria. These PLDs are often referred to as sphingomyelinase Ds (SMase Ds) because they cleave sphingomyelin (SM) to choline and "ceramide phosphate." The lipid product has actually been found to be a novel sphingolipid: ceramide 1,3-cyclic phosphate (Cer1,3P). Since there are no effective treatments for the injury induced by the bites of these spiders, SMase D/PLDs are attractive targets for therapeutic intervention, and some of their features will be described in this minireview. In addition, two simple methods are described for detecting the characteristic SMase D activity using a fluorescent SM analog, (N-[12-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]dodecanoyl]-SM (C12-NBD-SM), that is cleaved to C12-NBD-Cer1,3P, which is easily separated from other potential metabolites by thin-layer chromatography and visualized under UV light. Besides confirming that C12-NBD-Cer1,3P is the only product detected upon incubation of C12-NBD-SM with brown recluse spider venom, the method was also able to detect for the first time very low levels of activity in venom from another spider, Kukulcania hibernalis The simplicity of the methods makes it relatively easy to determine this signature activity of SMase D/PLD. SIGNIFICANCE STATEMENT: The sphingomyelinase D/phospholipase D that are present in the venom of the brown recluse spider and other sources cause considerable human injury, but detection of the novel sphingolipid product, ceramide 1,3-cyclic phosphate, is not easy by previously published methods. This minireview describes simple methods for detection of this activity that will be useful for studies of its occurrence in spider venoms and other biological samples, perhaps including lesions from suspected spider bites and infections.

Identification of a common epitope in knottins and phospholipases D present in Loxosceles sp venom by a monoclonal antibody

In the Americas and specially in Brazil, the Loxosceles intermedia, Loxosceles gaucho and Loxosceles laeta are the three most medically relevant brown spider species, and whose bites can lead to the condition known as loxoscelism. Here, we report the development of a tool capable of identifying a common epitope amongst Loxosceles sp. venom's toxins. A murine monoclonal antibody (LmAb12) and its recombinant fragments (scFv12P and diabody12P) have been produced and characterized. This antibody and its recombinant constructs were able to recognize proteins of Loxosceles spider venoms with specificity. The scFv12P variant was also able to detect low concentrations of Loxosceles venom in a competitive ELISA assay, displaying potential as a venom identification tool. The primary antigenic target of LmAb12 is a knottin, a venom neurotoxin, that has a shared identity of 100 % between the L. intermedia and L. gaucho species and high similarity to L. laeta. Furthermore, we observed LmAb12 was able to partially inhibit in vitro hemolysis, a cellular event typically induced by the Loxosceles sp. venoms. Such behavior might be due to LmAb12 cross-reactivity between the antigenic target of LmAb12 and the venom's dermonecrotic toxins, the PLDs, or even the existence of synergism between these two toxins.

Suspected Brown Recluse Spider Envenomation: Missed Diagnosis and Delayed Treatment of Loxoscelism: A Case Report

CASE

We report the case of a previously healthy 51-year-old man who presented to our hospital after worsening clinical appearance of his left ring finger, despite antibiotics and previous surgical drainage for suspected abscess at an outside institution 3 weeks ago. He was admitted to our hospital for surgical debridement and decompression. After suspicion of cutaneous loxoscelism based on the clinical record and corticosteroid administration, the patient presented a favorable evolution.

CONCLUSION

Cutaneous loxoscelism caused by a spider bite is present in Europe, mainly in the Mediterranean area, and should be considered in cases of skin infections which do not respond to antibiotics.

Viscerocutaneous Loxoscelism Manifesting with Myocarditis: A Case Report

Patient: Male, 16-year-old

Final Diagnosis: Toxic myocarditis

Symptoms: Cardiogenic shock • disseminated intravascular coagulation • heart failure

Medication: —

Clinical Procedure: Immunoglobulin therapy • plasmapharesis

Specialty: Critical Care Medicine • Toxicology

Clinical aspects, diagnosis and management of Loxosceles spider envenomation: literature and case review

The genus Loxosceles comprises 140 species widely distributed around the world. These spiders are nocturnal, sedentary and remarkably nonaggressive, although they cause accidents in humans with wide degrees of severity, generating signs and symptoms that define the clinical condition known as loxoscelism. Its local signs and symptoms were first reported in 1872, and over the years, a large medical literature has been accumulated; unfortunately, it is not always trustworthy. Assessing the reliability of such information, we reviewed 120 case reports of loxoscelism published in 84 articles over the past 20 years. This search allowed us to gather information on the clinical aspects, diagnosis and treatment of loxoscelism, showing that the severity of these accidents has multiple degrees and that it is influenced by many factors. Thus, coupled with epidemiological and species occurrence information, this study can be a useful tool for the clinical practice of loxoscelism. It may support and provide a multidisciplinary view that should be taken into consideration when establishing the therapeutic approach in cases of Loxosceles envenomation.

Forty Years of the Description of Brown Spider Venom Phospholipases-D

Spiders of the genus Loxosceles, popularly known as Brown spiders, are considered a serious public health issue, especially in regions of hot or temperate climates, such as parts of North and South America. Although the venoms of these arachnids are complex in molecular composition, often containing proteins with distinct biochemical characteristics, the literature has primarily described a family of toxins, the Phospholipases-D (PLDs), which are highly conserved in all Loxosceles species. PLDs trigger most of the major clinical symptoms of loxoscelism i.e., dermonecrosis, thrombocytopenia, hemolysis, and acute renal failure. The key role played by PLDs in the symptomatology of loxoscelism was first described 40 years ago, when researches purified a hemolytic toxin that cleaved sphingomyelin and generated choline, and was referred to as a Sphingomyelinase-D, which was subsequently changed to Phospholipase-D when it was demonstrated that the enzyme also cleaved other cellular phospholipids. In this review, we present the information gleaned over the last 40 years about PLDs from Loxosceles venoms especially with regard to the production and characterization of recombinant isoforms. The history of obtaining these toxins is discussed, as well as their molecular organization and mechanisms of interaction with their substrates. We will address cellular biology aspects of these toxins and how they can be used in the development of drugs to address inflammatory processes and loxoscelism. Present and future aspects of loxoscelism diagnosis will be discussed, as well as their biotechnological applications and actions expected for the future in this field.

Heterophilic antibodies in sera from individuals without loxoscelism cross-react with phospholipase D from the venom of Loxosceles and Sicarius spiders

Background

Loxoscelism is a severe human envenomation caused by Loxosceles spider venom. To the best of our knowledge, no study has evaluated the presence of antibodies against Loxosceles venom in loxoscelism patients without treatment with antivenom immunotherapy. We perform a comparative analysis for the presence of antibodies capable of recognizing Loxosceles venom in a group of patients diagnosed with loxoscelism and in a group of people without loxoscelism.

Methods

The detection of L. laeta venom, Sicarius venom and recombinant phospholipases D from Loxosceles (PLDs) in sera from people with loxoscelism (Group 1) and from healthy people with no history of loxoscelism (Group 2) was evaluated using immuno-dot blot, indirect ELISA, and Western blot.

Results

We found naturally heterophilic antibodies (IgG-type) in people without contact with Loxosceles spiders or any clinical history of loxoscelism. Either serum pools or single sera from Group 1 and Group 2 analyzed by dot blot tested positive for L. laeta venom. Indirect ELISA for venom recognition showed titles of 1:320 for Group 1 sera and 1:160 for Group 2 sera. Total IgG quantification showed no difference in sera from both groups. Pooled sera and purified IgG from sera of both groups revealed venom proteins between 25 and 32 kDa and the recombinant phospholipase D isoform 1 (rLlPLD1), specifically. Moreover, heterophile antibodies cross-react with PLDs from other Loxosceles species and the venom of Sicarius spider.

Conclusions

People without contact with the spider venom produced heterophilic antibodies capable of generating a cross-reaction against the venom of L. laeta and Sicarius spiders. Their presence and possible interference should be considered in the development of immunoassays for Loxosceles venom detection.

Bilateral optic neuropathy following bite from brown recluse spider (Loxosceles reclusa)

A 63-year-old female with history of a resected frontal lobe meningioma presented with bilaterally decreased vision after a bite from a brown recluse spider. The exam was significant for a left relative afferent pupillary defect, bilateral optic nerve pallor, decreased foveal sensitivity in the left eye and new bilateral visual field defects, despite stability of her meningioma. The findings remained stable at 1-year follow-up. To our knowledge, this is the first reported case of optic neuropathy secondary to a brown recluse spider bite. Visual field tests performed prior to the bite allowed us to compare and localize changes related to the bite.

A randomized controlled trial of trypsin to treat brown recluse spider bites in Guinea pigs

Brown recluse spider bites result in necrotic skin lesions for which there is no known antidote. Since venom toxins are proteins, a proteolytic enzyme like trypsin might be effective in reducing toxicity. The aim of this study was to conduct a randomized controlled trial of trypsin to treat brown recluse spider bites in guinea pigs. Subjects were 18 female guinea pigs. Anesthesia for injections was inhaled isoflurane. Analgesia was 0.05 mg/kg of buprenorphine twice a day as needed. Intervention was intradermal injection of 30 μg of brown recluse venom (Spider Pharm, Yarnell, AZ). Immediately after envenomation, subjects were randomized to two groups of nine: trypsin 10 μg in 1 mL normal saline and 1 mL of normal saline. The primary outcome was lesion area over a 10-day time period. Statistical analysis was performed with repeated measures ANOVA. Mean lesion area was smaller but not statistically different in the placebo group. Maximum lesion size occurred at day 4 in both groups, when lesion area was 76.1 ± 108.2 mm(2) in the placebo group and 149.7 ± 127.3 mm(2) in the treatment group. P value was 0.15 for placebo vs. treatment. This study did not establish a role for trypsin as a treatment for brown recluse spider bites in a guinea pig model.

Viscerocutaneous Loxoscelism in an Adult with Acute Generalized Exanthematous Pustulosis

This case describes an unusual presentation of a woman with viscerocutaneous (VCT) loxoscelism and exanthematous pustulosis. Due to a complex presentation resembling sepsis and errant information, she was unnecessarily treated with multiple antibiotics and intravenous immunoglobulin (IVIG) which may have complicated her course. Given recent reports of quick progression and death from a similar presentation, it is imperative that clinicians be familiar with signs, symptoms and complications of VCT loxoscelism, which can include hemolysis and acute exanthematous pustulosis.

Spider envenomation in North America

In North America, spider envenomation is perceived to be a greater threat than in actuality; however, it still is a valid source of morbidity and, very rarely, mortality. Only 2 groups (widows, recluses) are medically important on this continent. Widow bites affect the neuromuscular junction, have minor dermatologic expression, and are treated with analgesics and antivenom. Recluse bites vary from mild, self-limiting rashes to extensive dermonecrosis. Recent awareness of methicillin-resistant Staphylococcus aureus as a ubiquitous cause of skin injury that is often mistaken as attributable to recluse bites has questioned the credence of spiders being the cause of idiopathic wounds.

[Necrotic arachnidism in the south of France: two clinical cases of loxoscelism]

BACKGROUND

loxosceles spiders are found throughout the world and are responsible for numerous cases of envenomation in America and Southern Europe. We describe, to our knowledge for the first time in France, two clinical cases of cutaneous loxoscelism.

CASE REPORT

two cases of skin necrosis arising after supposed spider bites were grouped together because of their similar clinical presentation: an initial painless bite and rapid development of an inflammatory and painful cutaneous lesion with a central hemorrhagic bulla surrounded by a perimeter of blanched skin (the "red, white, and blue" sign). The outcome in both cases was deep skin necrosis and chronic ulceration requiring surgical treatment.

DISCUSSION

loxoscelism can result in dermonecrosis. Although our cases were not documented by capture of the spider, the diagnosis of cutaneous loxoscelism was supported by the characteristic appearance of the lesion, a typical clinical course, elimination of differential diagnoses, and the confirmed presence of Loxosceles rufescens in the region.

CONCLUSION

loxoscelism can occur in the south of France and although rare, must be considered in this region as a possible cause of skin necrosis.

Brown spider (Loxosceles genus) venom toxins: tools for biological purposes

Venomous animals use their venoms as tools for defense or predation. These venoms are complex mixtures, mainly enriched of proteic toxins or peptides with several, and different, biological activities. In general, spider venom is rich in biologically active molecules that are useful in experimental protocols for pharmacology, biochemistry, cell biology and immunology, as well as putative tools for biotechnology and industries. Spider venoms have recently garnered much attention from several research groups worldwide. Brown spider (Loxosceles genus) venom is enriched in low molecular mass proteins (5–40 kDa). Although their venom is produced in minute volumes (a few microliters), and contain only tens of micrograms of protein, the use of techniques based on molecular biology and proteomic analysis has afforded rational projects in the area and permitted the discovery and identification of a great number of novel toxins. The brown spider phospholipase-D family is undoubtedly the most investigated and characterized, although other important toxins, such as low molecular mass insecticidal peptides, metalloproteases and hyaluronidases have also been identified and featured in literature. The molecular pathways of the action of these toxins have been reported and brought new insights in the field of biotechnology. Herein, we shall see how recent reports describing discoveries in the area of brown spider venom have expanded biotechnological uses of molecules identified in these venoms, with special emphasis on the construction of a cDNA library for venom glands, transcriptome analysis, proteomic projects, recombinant expression of different proteic toxins, and finally structural descriptions based on crystallography of toxins.

Loxoscelism and Negative Pressure Wound Therapy (Vacuum-Assisted Closure): A Clinical Case Series

Brown recluse spider (Loxosceles sp) bites continue to be a significant challenge to manage clinically. Sequelae from these lesions range from chronic necrotic ulcers that persist for months to an acute life-threatening course of sepsis. Negative pressure wound therapy using vacuum-assisted closure (VAC) has been described for use in both acute and chronic wounds. We present a novel application for the use of this therapy in a retrospective review of eight clinical cases treated with the VAC.

Brown recluse spider (Loxosceles reclusa) envenomation in small animals

OBJECTIVE

To provide a comprehensive review of relevant literature regarding the brown recluse spider (BRS) and to define those criteria that must be satisfied before making a diagnosis of brown recluse envenomation.

ETIOLOGY

The complex venom of the BRS contains sphingomyelinase D, which is capable of producing all the clinical signs in the human and some animal models.

DIAGNOSIS

There is no current commercially available test. In humans there are many proposed guidelines to achieve a definitive diagnosis; however, there are no established guidelines for veterinary patients.

THERAPY

Currently, no consensus exists for treatment of BRS envenomation other than supportive care, which includes rest, thorough cleaning of the site, ice, compression, and elevation.

PROGNOSIS

Prognosis varies based on severity of clinical signs and response to supportive care.

Duration of Loxosceles reclusa venom detection by ELISA from swabs

BACKGROUND

Diagnosis of Loxosceles reclusa envenomations is currently based upon clinical presentation. An enzyme-linked immunosorbent assay (ELISA) can detect surface Loxosceles venom at the envenomation site, allowing diagnostic confirmation. The length of time that venom on the skin is recoverable non-invasively is unknown.

MATERIALS AND METHODS

To investigate duration of recoverable venom antigen, whole venom and fractionated sphingomyelinase D venom aliquots were injected subcutaneously in New Zealand White rabbits. Cotton and Dacron swabs were compared for venom recovery over a 21-day period using a surface swab technique.

RESULTS

Significant amounts of Loxosceles reclusa antigen were found on the surface of rabbit skin after experimental injection of whole venom and sphingomyelinase D. The duration of recoverable antigen using this experimental model appears to be at least two weeks and as long as 21 days in some cases.

CONCLUSIONS

Because the duration of the recoverable antigen is seen to be at least two weeks, the ELISA venom test appears capable of detecting venom on most patients presenting with Loxosceles envenomations. This detection system will allow the physician more accurate determination of whether the lesion is from a brown recluse spider or some other agent that can cause this type of necrotic ulcer.

Loxosceles reclusa bite to the eyelid

PURPOSE

The authors report a case of Loxosceles reclusa infestation on the eyelid.

METHODS

The specimen collected by swabbing the lesions with gauze was tested by using a venom-specific enzyme-linked immunosorbent assay. Loxosceles venom was detected in specimen. The patient was managed with conservative therapy that included saline compresses and ocular lubrication.

RESULTS

The case presented with severe edema and necrosis on the left upper eyelid. On laboratory examination, a significant left shift of white blood cell count was detected. Although residual scar of the eyelid and punctate epitheliopathy on the inferior of cornea was detected, vision was not impaired.

CONCLUSIONS

Supportive therapy may be reasonable treatment for Loxosceles reclusa infestation on the eyelids. The presence of venom proteins detected with an enzyme-linked immunosorbent assay technique is beneficial for supporting the diagnosis of Loxosceles envenomatio.

Osteomyelitis of the mandibular symphysis caused by brown recluse spider bite

BACKGROUND

Brown recluse spider bites cause significant trauma via their tissue toxic venom. Diagnosis of these injuries and envenomation is difficult and many times presumptive. Treatment is varied and dependent upon presentation and course of injury.

MATERIALS AND METHODS

We present a case of a previously unreported incidence of osteomyelitis of the mandible as a result of a brown recluse spider bite. A review of the literature and discussion of diagnosis and treatment of brown recluse spider bites are presented.

RESULTS

Osteomyelitis of the mandible causing a chronic wound was the presenting finding of a patient with a history of spider bite and exposure to brown recluse spiders. Operative debridement and wound closure resulted in successful treatment. Brown recluse spider envenomation varies in its presentation and treatment is based on the presenting clinical picture.

CONCLUSION

Treatment regimens for brown recluse spider bite envenomation should include the basics of wound care. Systemic antibiotics, topical antimicrobials, dapsone, and surgical debridement are valuable adjuncts of treatment, as indicated, based on the clinical course.

Biotechnological applications of brown spider (Loxosceles genus) venom toxins

Loxoscelism (the term used to define accidents by the bite of brown spiders) has been reported worldwide. Clinical manifestations following brown spider bites are frequently associated with skin degeneration, a massive inflammatory response at the injured region, intravascular hemolysis, platelet aggregation causing thrombocytopenia and renal disturbances. The mechanisms by which the venom exerts its noxious effects are currently under investigation. The whole venom is a complex mixture of toxins enriched with low molecular mass proteins in the range of 5-40 kDa. Toxins including alkaline phosphatase, hyaluronidase, metalloproteases (astacin-like proteases), low molecular mass (5.6-7.9 kDa) insecticidal peptides and phospholipases-D (dermonecrotic toxins) have been identified in the venom. The purpose of the present review is to describe biotechnological applications of whole venom or some toxins, with especial emphasis upon molecular biology findings obtained in the last years.

Diagnosis of loxoscelism in a child confirmed with an enzyme-linked immunosorbent assay and noninvasive tissue sampling

BACKGROUND

Confirmation of mild bites caused by Loxosceles reclusa with swab testing has not been previously documented, to our knowledge.

METHODS

We report a case using an enzyme-linked immunosorbent assay (ELISA) test.

RESULTS

A lesion lacking necrosis or other specific signs of loxoscelism was confirmed by identification of the Loxosceles venom and further confirmed by identification of a spider found in the patient's bed.

LIMITATIONS

This is a pilot single-case report for this enzyme-linked immunosorbent assay test.

CONCLUSIONS

A sensitive and specific enzyme-linked immunosorbent assay designed to detect Loxosceles venom, using a specimen obtained by swabbing the lesion, can aid in diagnosis of loxoscelism.

The efficacy of antivenom in loxoscelism treatment

Loxoscelism or brown spider envenomation is the most important form of araneism in some countries and constitutes the third cause of accidents by venomous animals in Brazil. The treatment of Loxosceles bites is still controversial, with a variety of interventions proposed and tried, such as antivenom. The majority of clinical studies demonstrate a significant delay between a spider's bite and presentation for treatment, and this delay is thought to lead to an ineffective administration of a specific antivenom. Even in Brazil, where the antivenom therapy has been indicated more frequently than in other countries, there are still doubts about its real capacity to neutralize local and systemic effects of the envenomation and the ideal period for its administration. Thus, various studies in animal models have tried to correlate the time of envenomation with the application of the antivenom and the permanence of the venom in circulation or in dermonecrotic lesions. The purpose of this study was to evaluate the use of antivenom in loxoscelism treatment and to systematize the results of studies in animals and humans available in the last 30 years, making possible a more critical analysis of the efficacy of the antivenom or its therapeutic value in bites by spiders of the genus Loxosceles.

Loxoscelism

Loxoscelism (bites by spiders of the genus Loxosceles) is the only proven arachnological cause of dermonecrosis. Although Loxosceles spiders can be found worldwide, their distribution is heavily concentrated in the Western Hemisphere, particularly the tropical urban regions of South America. Although Loxosceles bites are usually mild, they may ulcerate or cause more severe, systemic reactions. These injuries mostly are due to sphingomyelinase D in the spider venom. There is no proven effective therapy for Loxosceles bites, although many therapies are reported in the literature.

Brown Recluse Spider Envenomation

Brown recluse spider bite is a common diagnosis in almost every state in America. In fact, cases have been reported in areas where the spider has never been seen. A review of medical literature reveals that most current concepts regarding brown recluse spider envenomation are based on supposition. In this article, we attempt to review critically our present understanding of brown recluse bites with a focus on the published evidence.

Brown spiders and loxoscelism

Accidents caused by brown spiders (Loxosceles genus) are classically associated with dermonecrotic lesions and systemic manifestations including intravascular haemolysis, disseminated intravascular coagulation and acute renal failure. Systemic reactions occur in a minority of cases, but may be severe in some patients and occasionally fatal. The mechanisms by which Loxosceles venom exerts these noxious effects are currently under investigation. The venom contains several toxins, some of which have been well-characterised biochemically and biologically. The purpose of the present review is to describe some insights into loxoscelism obtained over the last ten years. The biology and epidemiology of the brown spider, the histopathology of envenomation and the immunogenicity of Loxosceles venom are reviewed, as are the clinical features, diagnosis and therapy of brown spider bites. The identification and characterisation of some toxins and the mechanism of induction of local and systemic lesions caused by brown spider venom are also discussed. Finally, the biotechnological application of some venom toxins are covered.

Arthropods in dermatology

Arthropods are important in medicine for a multitude of reasons. Their bites and stings may induce allergic reactions, ranging from annoying to life-threatening. Many arthropod products are also capable of inciting allergic responses in sensitized persons. In recent years, bites and stings have gained greater attention owing to increased concern about disease transmission. A common hypersensitivity response to arthropod bites, stings, and products is papular urticaria. This eruption occurs primarily in children, who eventually "outgrow" this disease, probably through desensitization after multiple arthropod exposures. Papular urticaria is most often caused by fleas or bedbugs, but virtually any arthropod is capable of inducing such a reaction. Two arthropod classes of medical importance are the Arachnida (spiders, scorpions, ticks, and mites) and the Insecta (lice, fleas, bedbugs, flies, bees, and ants). Animals in these two classes are probably responsible for more morbidity and mortality worldwide than are any other group of venomous creatures. In general, the diagnosis of arthropod bites and stings is dependent on maintenance of a high index of suspicion and familiarity with the arthropod fauna not only in one's region of practice, but also in the travel regions of one's patients. Learning objective At the completion of this learning activity, participants should be familiar with the clinical manifestations caused by a variety of arthropods as well as the treatment and possible sequelae of arthropod attacks.

Arachnid envenomation

This article focuses on the medically relevant arachnid species found in North America and selected other arachnids from around the world. While it is largely still true that the geographic location of the envenomation assists in determining the species responsible, the booming trade in arachnids as exotic pets should prompt the clinician to inquire into this possibility. Expert advice should be sought in either case; species identification is critical in determining the need for and proper type of antivenom therapy.

Production of monoclonal antibodies capable of neutralizing dermonecrotic activity of Loxosceles intermedia spider venom and their use in a specific immunometric assay

We have produced 13 mAbs for Loxosceles intermedia crude venom. Twelve were reactive against proteins of 32-35 kDa and one of these Li mAb(7) showed high neutralizing potency for the dermonecrotic activity of L. intermedia venom. This Li mAb(7) showed no cross-reactivity, with Loxosceles laeta (Brazil), L. laeta (Perú) and Loxosceles gaucho venoms. The mAbs were produced by immunization with the crude venom and screened by enzyme-linked immunosorbent assay (ELISA) using L. intermedia whole venom or dermonecrotic fraction (DNF) as antigens coated onto microtitre plates. A sensitive two-site immunometric assay was designed and shown to be useful for identifying and quantifying DNF from L. intermedia in biological samples. The Li mAb(7) coated onto microtitre plates and hyperimmune horse anti-L. intermedia IgGs prepared by immunoaffinity chromatography and conjugated to horseradish peroxidase were used to set up a sandwich-type ELISA. Measurable absorbance signals were obtained with 0.2 ng of L. intermedia crude venom per assay.

Sudden unexplained hemolysis occurring in an infant due to presumed Loxosceles envenomation

We report the case of a 3-week-old infant referred for evaluation of sudden onset jaundice and unexplained hemolysis. After an exhaustive workup, the most likely etiology was found to be envenomation by a brown recluse spider, Loxosceles reclusa. This case underscores the fact that severe loxoscelism may occur in the absence of the classically described necrotic cutaneous lesion, and represents one of the youngest presumed cases of loxoscelism. We present the case to illustrate the importance of considering loxoscelism in the differential diagnosis of sudden massive hemolysis in children, particularly in endemic areas of the midwestern and southern United States.

Brown recluse spiders: a review to help guide physicians in nonendemic areas

The brown recluse spider (Loxosceles reclusa) exists in significant populations mainly in the midwestern United States. Although bites can cause significant harm, envenomation is infrequent, and cases are usually clinically insignificant. Proper knowledge of the spider's habitat and lifestyle as well as the signs and symptoms of loxoscelism are needed to assess clinical cases adequately. Loxoscelism can masquerade as many serious pathologies, and vice versa, so it is important for the clinician to explore all possibilities in the differential diagnosis thoroughly. Treatments are controversial, and no conclusive test for envenomation is currently available. This review provides information to help physicians, especially in nonendemic areas, include or exclude brown recluse bite in the clinical diagnosis and provide proper care.