Acute vancomycin-dependent immune thrombocytopenia as an anamnestic response.

Abstract

Drug-related thrombocytopenia is a well-described but relatively rare complication of antibiotic therapy. In this entity, platelet destruction is immune-mediated, often resulting in a precipitous drop in platelet count over a short period of time. Most of these cases of thrombocytopenia are drug-dependent, as discontinuation of the offending agent frequently results in a timely return to baseline, pre-exposure platelet levels. We report the case of a 61-year-old male patient receiving vancomycin and ceftazidime for lower extremity wet gangrene who experienced a marked, acute reduction in platelet count 12 to 15 hours after starting antibiotic therapy. There was no readily apparent clinical or laboratory explanation for his thrombocytopenia. Pre- and post- antibiotic serum samples were preserved and sent for drug-dependent platelet antibody analysis. The pre-exposure specimen revealed the presence of IgG vancomycin-dependent platelet antibodies, while the post-exposure specimen demonstrated both IgG and IgM vancomycin-dependent platelet antibodies. Ceftazidime-dependent platelet antibodies were not identified in either sample. These findings indicate prior sensitization to vancomycin, with subsequent acute production of IgM anti-platelet antibodies after re-exposure to the antibiotic. The patient's antibiotics were held after the acute-onset of thrombocytopenia with subsequent restoration of normal platelet counts within 4 days of drug withdrawal, and the patient at no time experienced significant adverse bleeding events. Antibiotic therapy with vancomycin is a rare and perhaps overlooked cause for new-onset thrombocytopenia in hospitalized patients. This case illustrates that the development of severe thrombocytopenia within hours of vancomycin administration does not rule out drug-related immune clearance, as the rapid platelet destruction may indicate an anamnestic antibody response to the drug after previous exposure. In such a scenario, immediate discontinuation of vancomycin is recommended to improve platelet counts. From a laboratory perspective, retrieval of serum both pre- and post-administration of vancomycin is most helpful in determining a patient's drug-immunization status and can help guide safe drug use during future infections.

• Authors: Barton Kenney, Christopher A Tormey
• Journal: Platelets (Platelets) Vol. 19 Issue 5 Pg. 379-83 (Aug 2008) ISSN: 1369-1635 [Electronic] England
• PMID: 18791945 (Publication Type: Case Reports, Journal Article)

Chemical References

• Anti-Bacterial Agents
• Antigens, Human Platelet
• Autoantibodies
• Immunoglobulin G
• Immunoglobulin M
• Vancomycin
• Ceftazidime

Topics

• Acute Disease
• Amputation, Surgical
• Anti-Bacterial Agents (administration & dosage, adverse effects, immunology, therapeutic use)
• Antigens, Human Platelet (immunology)
• Autoantibodies (immunology)
• Bacteremia (drug therapy)
• Ceftazidime (administration & dosage, therapeutic use)
• Drug Therapy, Combination
• Foot Diseases (drug therapy)
• Gram-Positive Bacterial Infections (drug therapy)
• Humans
• Immunoglobulin G (immunology)
• Immunoglobulin M (biosynthesis, immunology)
• Immunologic Memory
• Male
• Middle Aged
• Purpura, Thrombocytopenic, Idiopathic (chemically induced, immunology)
• Surgical Wound Infection (drug therapy)
• Vancomycin (administration & dosage, adverse effects, immunology, therapeutic use)