Common emergence of amantadine- and rimantadine-resistant influenza A viruses in symptomatic immunocompromised adults.
The importance and significance of amantadine- or rimantadine-resistant influenza viruses in immunocompromised patients was studied in a population of adult bone marrow transplant (BMT) recipients and patients with leukemia prospectively cultured for respiratory viruses. Influenza A viruses were isolated from 29 patients with acute respiratory illness (14 BMT recipients and 15 patients with leukemia). Fifteen patients (52%) received amantadine (n = 4) or rimantadine (n = 11) therapy. All influenza isolates recovered from six patients shedding virus for > or = 3 days were screened for antiviral susceptibility; resistant isolates were further genetically characterized. Initial influenza isolates were susceptible to amantadine or rimantadine, but subsequent isolates from five of six patients were resistant. Influenza-associated mortality was similar among patients with and without documented antiviral resistance (2 of 5 vs. 5 of 24). We conclude that development of antiviral resistance in immunocompromised individuals should be considered when they have been treated with antivirals and have shed influenza virus for a prolonged period. Isolation procedures should be instituted for all immunocompromised patients with influenza, both during and after therapy with amantadine or rimantadine.
Englund
J A
JA
Acute Viral Respiratory Diseases Unit, Baylor College of Medicine, Houston, Texas 77030, USA.
Champlin
R E
RE
Wyde
P R
PR
Kantarjian
H
H
Atmar
R L
RL
Tarrand
J
J
Yousuf
H
H
Regnery
H
H
Klimov
A I
AI
Cox
N J
NJ
Whimbey
E
E
D000328:Adult; D000547:Amantadine / Q000627:therapeutic use*; D000998:Antiviral Agents / Q000627:therapeutic use*; D016026:Bone Marrow Transplantation / Q000009:adverse effects; D004352:Drug Resistance, Microbial; D006801:Humans; D009980:Influenza A virus / Q000187:drug effects*; D007251:Influenza, Human / Q000188:drug therapy* / Q000209:etiology; D007938:Leukemia / Q000150:complications; D008875:Middle Aged; D009894:Opportunistic Infections / Q000188:drug therapy / Q000209:etiology / Q000821:virology*; D012299:Rimantadine / Q000627:therapeutic use*
D000998:Antiviral Agents; D012299:Rimantadine; D000547:Amantadine