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Karen C. Carroll, M.D.

Headshot of Karen C. Carroll
  • Director, Division Medical Microbiology
  • Professor of Pathology


General Internal Medicine

Research Interests

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


Dr. Karen Carroll is a professor of pathology at the Johns Hopkins University School of Medicine. Her areas of clinical expertise include Medical Microbiology and Infectious Diseases. Dr. Carroll serves as the Director of the Division of Medical Microbiology and the Director of the ACGM-accredited fellowship program in medical microbiology in the 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 medical microbiology 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 novel 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, the Infectious Diseases Society Kass Award and named lecture in 2015, and the Illinois Society for Microbiology Pasteur Award.  She is a member of several professional organizations, including the American Society of Microbiology. She has published more than 250 peer-reviewed publications, most recently in the areas of healthcare-associated infections, such as Clostridium difficile, MRSA, VRE and MDR gram-negative bacteria. more


  • Director, Division Medical Microbiology
  • Director, ACGME Accredited Medical Microbiology Fellowship Program
  • Section Director Molecular Epidemiology
  • Associate Director, Bacteriology Laboratory
  • Professor of Pathology
  • Joint Appointment in Medicine

Departments / Divisions

Research & Publications

Research Summary

Dr. Carroll's research interests include diagnostic test evaluation and development for the detection of microbial pathogens in clinical specimens. Projects have included implementation of MALDI-TOF MS for microbial identification, 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. In addition, her research recently has focused on evaluation and implementation of syndromic panel tests for bacteremia and fungemia detection. More recently Dr. Carroll has collaborated with researchers on novel rapid microfluidics platforms for detection of a variety of pathogens.  She has participated in programs to foster appropriate test utilization and diagnostic stewardship.

Selected Publications

Riedel S, Neoh KM, Eisinger SW, Dam LM, Tekle T, Carroll KC. 2014. Comparison of commercial antimicrobial susceptibility test methods for testing of Staphylococcus aureus and enterococci against vancomycin, daptomycin, and linezolid. J Clin Microbiol 52:2216-22.

Suwantarat N, Carroll KC, Tekle T, Ross T, Maragakis LL, Cosgrove, Milstone AM. 2014. High prevalence of reduced chlorhexidine susceptibility in organisms causing central line-associated bloodstream infections. Infect Control Hosp. Epidemiol. 35:1183-86.

Salimnia H, Fairfax M, Lephart P, Morgan M, Gilbreath J, Butler-Wu S, Templeton K, Hamilton F, Wu F, Buckner R, Fuller D, Davis T, Abdelhamed A, Jacobs M, Miller A, Pfrommer B, and Carroll KC. 2014. An International, Prospective, Multi-Center Evaluation of the Combination of the AdvanDx Staphylococcus QuickFISH BC with the mecA XpressFISH for the Detection of Methicillin-Resistant Staphylococcus aureus from Positive Blood Culture. J Clin Microbiol 52:3928.

Suwantarat N, Roberts A, R Prestridge A, Seeley R, Speser S, Harmon C, Zhang C, Henciak S, Stamper PD, Ross T, Carroll KC. 2014. Comparison of five chromogenic media for the recovery of vancomycin resistant enterococci (VRE) from fecal samples. J Clin Microbiol 52:4039-42.

Farley JE, Hayat MJ, Sacamano PL, Howard T, Carroll K. 2015. Prevalence and Risk Factors for MRSA in an HIV-positive Cohort. Amer J Infect Control 43:329-35.

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.

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.

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.

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.

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.

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.

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

Courses and Syllabi

  • Genes to Society Microbiology and Infectious Diseases
    Johns Hopkins University School of Medicine
    2019 - 2020

Activities & Honors


  • BD Award for Research in Clinical Microbiology, American Society of Microbiology, 2011
  • 25th Edward H Kass Award and Named Lecture, Infectious Diseases Society of America, 2015
  • Pasteur Award, Illinois Society for Microbiology, 2017


  • American Academy of Microbiology
  • American Society for Clinical Pathology
  • American Society for Microbiology


  • College of American Pathologists
  • Infectious Diseases Society of America
  • Society for Healthcare Epidemiologists of America

Professional Activities

  • Cohort, Leadership Program for Women Faculty, 2012
  • Committee on Laboratory Practices Liaison, American College of Microbiology
  • Faculty Senate, Johns Hopkins University School of Medicine, 2009
  • Director Microbiology Laboratory, Johns Hopkins Hospital
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