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Emergence and Transmission of Amantadine-Resistant Influenza A in a Nursing Home

Authors

  • Margo Schilling MD,

    1. From the *University of Iowa, Iowa City, IowaEastern Virginia Medical School, Norfolk, VirginiaWisconsin Veterans Home, King, Wisconsin§Centers for Disease Control and Prevention, Atlanta, GeorgiaUniversity of Wisconsin, Madison, Wisconsin.
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  • Stefan Gravenstein MD,

    1. From the *University of Iowa, Iowa City, IowaEastern Virginia Medical School, Norfolk, VirginiaWisconsin Veterans Home, King, Wisconsin§Centers for Disease Control and Prevention, Atlanta, GeorgiaUniversity of Wisconsin, Madison, Wisconsin.
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  • Paul Drinka MD,

    1. From the *University of Iowa, Iowa City, IowaEastern Virginia Medical School, Norfolk, VirginiaWisconsin Veterans Home, King, Wisconsin§Centers for Disease Control and Prevention, Atlanta, GeorgiaUniversity of Wisconsin, Madison, Wisconsin.
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  • Nancy Cox PhD,

    1. From the *University of Iowa, Iowa City, IowaEastern Virginia Medical School, Norfolk, VirginiaWisconsin Veterans Home, King, Wisconsin§Centers for Disease Control and Prevention, Atlanta, GeorgiaUniversity of Wisconsin, Madison, Wisconsin.
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  • Peggy Krause RN,

    1. From the *University of Iowa, Iowa City, IowaEastern Virginia Medical School, Norfolk, VirginiaWisconsin Veterans Home, King, Wisconsin§Centers for Disease Control and Prevention, Atlanta, GeorgiaUniversity of Wisconsin, Madison, Wisconsin.
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  • Laura Povinelli PhD,

    1. From the *University of Iowa, Iowa City, IowaEastern Virginia Medical School, Norfolk, VirginiaWisconsin Veterans Home, King, Wisconsin§Centers for Disease Control and Prevention, Atlanta, GeorgiaUniversity of Wisconsin, Madison, Wisconsin.
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  • Peter Shult PhD

    1. From the *University of Iowa, Iowa City, IowaEastern Virginia Medical School, Norfolk, VirginiaWisconsin Veterans Home, King, Wisconsin§Centers for Disease Control and Prevention, Atlanta, GeorgiaUniversity of Wisconsin, Madison, Wisconsin.
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  • This research was supported, in part, by National Institute of Health Grants RO1AG09632 and KO8AG00548. Dr. Schilling is supported by a Geriatric Academic Career Award from the Health Resources and Services Administration. Presented at the annual meeting of the American Geriatrics Society, Nashville, Tennessee, May 2000.

Margo Schilling, MD, University of Iowa Health Center, SE613 GH, 200 Hawkins Dr. Iowa City, IA 52242. E-mail: margo-schilling@uiowa.edu

Abstract

Objectives: To prospectively detect amantadine-resistant influenza when amantadine was used for influenza A outbreak control.

Design: Prospective clinical surveillance and viral culture of all new respiratory illnesses during the course of amantadine prophylaxis.

Setting: A 721-bed, 14-ward nursing home for veterans and spouses during an influenza A outbreak (1993–94).

Participants: Residents of a veterans hospital and their spouses.

Measurements: Nasopharyngeal and throat viral culture. All residents with positive cultures who developed new respiratory symptoms while receiving or residing on a unit receiving amantadine prophylaxis had antiviral-resistance testing and polymerase chain reaction restriction analyses performed.

Results: Amantadine prophylaxis was administered sequentially on nine of 14 wards to all well residents for 14 to 31 days/ward to control influenza outbreaks between December 9, 1993, and January 28, 1994. Amantadine treatment was simultaneously provided to 29 ill residents. Between December 3, 1993, and January 22, 1994, 68 culture-positive cases of influenza A were detected. Twenty subjects were receiving or residing on units receiving amantadine prophylaxis. Amantadine sensitivity testing could be performed on 16 residents; 12 residents had amantadine resistant strains. Four of the 12 had not received any antiviral treatment. Illness onset ranged from 1 to 22 days after amantadine prophylaxis was begun on the individual's unit. Two ribonucleic acid (RNA) mutations in the gene coding the M2 protein transmembrane region were observed that were clustered in time and space. Isolates from two roommates, one receiving amantadine for 18 days and one on no antiviral, had identical RNA sequences.

Conclusion: Antiviral resistance may be responsible for failure of prophylaxis in nursing home outbreaks. Strategies that use different classes of antivirals for prophylaxis and treatment may limit emergence and transmission of resistant virus.

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