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Karen C. Carroll, M.D.

Director, Division Medical Microbiology
Professor of Pathology
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Main Location

The Johns Hopkins Hospital

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  • Director, Division Medical Microbiology
  • Director, Medical Microbiology Fellowship Program
  • Professor of Pathology
  • Joint of Medicine


General Internal Medicine

Research Interests

Evaluation of diagnostic platforms and epidemiology of healthcare associated infections such as MRSA and Clostridium difficile.


Dr. Karen Carroll is a professor of pathology and medicine at the Johns Hopkins University School of Medicine. Her areas of clinical expertise include general internal medicine. Dr. Carroll serves as the director of the Division Medical Microbiology and the director of the medical microbiology fellowship program at Department of Pathology.

Dr. Carroll earned her M.D. from the University of Maryland School of Medicine. She completed her residency at the University of Rochester Medical Center, and performed a fellowship in pathology at the University of Utah and a fellowship in infectious disease at the University of Massachusetts Medical School.

Her research interests include the evaluation of diagnostic platforms and epidemiology of healthcare-associated infections, such as MRSA and Clostridium difficile.

Dr. Carroll has received numerous awards for excellence in teaching, and was the recipient of the BD Award for Research in Clinical Microbiology from the American Society of Microbiology in 2011. She is a member of several professional organizations, including the American Society of Microbiology. She has published more than 125 peer-reviewed publications, most recently in the areas of healthcare-associated infections, such as Clostridium difficile, MRSA, VRE and MDR gram-negative bacteria.


  • English


Member, American Society of Microbiology

Member, Society for Healthcare Epidemiologists of America

Member, American Society for Clinical Pathology

Fellow, College of American Pathologists

Fellow, American Academy of Microbiology

Fellow, Infectious Diseases Society of America

Additional Resources +
  • Education +


    • The University of Utah (Salt Lake City UT) (2000)
    • University of Maryland School of Medicine (Baltimore MD) (1979)


    • University of Rochester Medical Center/ Internal Medicine (Rochester NY) (1983)


    • The University of Utah/ Pathology (Salt Lake City UT) (1990)
    • University of Massachusetts Medical School/ Infectious Disease (Worcester MA) (1986)


    • Medical Microbiology, American Board of Pathology (1991)
    • Infectious Disease, American Board of Internal Medicine (1988)
    • Internal Medicine, American Board of Internal Medicine (1982)
  • Research & Publications +

    Research Summary

    Dr. Carroll's research interests include diagnostic test evaluation and development for the detection of microbial pathogens in clinical specimens. Recent projects have included: use of 16S rDNA-sequencing for identification of non-tuberculous mycobacteria; evaluation of molecular strain typing techniques for epidemiological analysis; development of molecular and non-molecular assays for rapid identification and susceptibility testing of MRSA; and evaluation of methods for Clostridium difficile detection.

    Selected Publications

    1. Francis JS, Doherty MC, Lopatin U, Johnston CP, Sinha G, Ross T, Cai M, Hansel NN, Perl T, Ticehurst JR, Carroll K, Thomas DL, Nuermberger E, Bartlett JG. "Severe community-onset pneumonia in healthy adults caused by methicillin-resistant Staphylococcus aureus carrying the Panton-Valentine leukocidin genes." Clin Infect Dis. 2005 Jan 1;40(1):100-7. Epub 2004 Dec 7.
    2. Flayhart D, Lema C, Borek A, Carroll KC. "Comparison of the BBL CHROMagar Staph aureus agar medium to conventional media for detection of Staphylococcus aureus in respiratory samples." J Clin Microbiol. 2004 Aug;42(8):3566-9.
    3. Shutt CK, Samore M, Carroll KC. "Comparison of the Denka Seiken slide agglutination method to the quellung test for serogrouping of Streptococcus pneumoniae isolates." J Clin Microbiol. 2004 Mar;42(3):1274-6.
    4. Cloud JL, Conville PS, Croft A, Harmsen D, Witebsky FG, Carroll KC. "Evaluation of partial 16S ribosomal DNA sequencing for identification of nocardia species by using the MicroSeq 500 system with an expanded database." J Clin Microbiol. 2004 Feb;42(2):578-84.
    5. Carroll KC, Adamson K, Korgenski K, Croft A, Hankemeier R, Daly J, Park CH. "Comparison of a commercial reversed passive latex agglutination assay to an enzyme immunoassay for the detection of Shiga toxin-producing Escherichia coli." Eur J Clin Microbiol Infect Dis. 2003 Nov;22(11):689-92. Epub 2003 Oct 23.
    6. Cloud JL, Hymas WC, Turlak A, Croft A, Reischl U, Daly JA, Carroll KC. "Description of a multiplex Bordetella pertussis and Bordetella parapertussis LightCycler PCR assay with inhibition control." Diagn Microbiol Infect Dis. 2003 Jul;46(3):189-95.
    7. Cloud JL, Neal H, Rosenberry R, Turenne CY, Jama M, Hillyard DR, Carroll KC. "Identification of Mycobacterium spp. by using a commercial 16S ribosomal DNA sequencing kit and additional sequencing libraries." J Clin Microbiol. 2002 Feb;40(2):400-6.
  • Academic Affiliations & Courses +
  • Activities & Honors +


    BD Award for Research in Clinical Microbiology, American Society of Microbiology, 2011

    Professional Activities

    Cohort, Leadership Program for Women Faculty, 2012 - 2013

    Faculty Senate, Johns Hopkins University School of Medicine

    Committee on Laboratory Practices Liaison, American College of Microbiology

  • Videos & Media +
  • Events +
  • Contact & Locations +


    The Johns Hopkins Hospital
    600 N. Wolfe Street
    Baltimore, MD 21287
    Phone: 410-955-5077
    Appointment Phone: 410-955-1725
    Fax: 410-614-8087
    Location Map


    • Pathology - Medical Microbiology
    • Medicine - Infectious Diseases

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