Antimicrobial Heteroresistance: an Emerging Field in Need of Clarity

Omar M. El-Halfawy, Miguel A. Valvano

Research output: Contribution to journalArticlepeer-review

179 Citations (Scopus)
793 Downloads (Pure)


SUMMARY: "Heteroresistance" describes a phenomenon where subpopulations of seemingly isogenic bacteria exhibit a range of susceptibilities to a particular antibiotic. Unfortunately, a lack of standard methods to determine heteroresistance has led to inappropriate use of this term. Heteroresistance has been recognized since at least 1947 and occurs in Gram-positive and Gram-negative bacteria. Its clinical relevance may be considerable, since more resistant subpopulations may be selected during antimicrobial therapy. However, the use of nonstandard methods to define heteroresistance, which are costly and involve considerable labor and resources, precludes evaluating the clinical magnitude and severity of this phenomenon. We review the available literature on antibiotic heteroresistance and propose recommendations for definitions and determination criteria for heteroresistant bacteria. This will help in assessing the global clinical impact of heteroresistance and developing uniform guidelines for improved therapeutic outcomes.

Original languageEnglish
Pages (from-to)191-207
Number of pages17
JournalClin. Microbiol. Rev.
Issue number1
Publication statusPublished - 01 Jan 2015


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