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Volume 17, Number 6—June 2011


Extended-Spectrum β-Lactamase–producing Escherichia coli in Neonatal Care Unit

Suggested citation for this article

To the Editor: Tschudin-Sutter et al. provide convincing evidence of transfer of an extended-spectrum β-lactamase–producing Escherichia coli strain from a mother to her vaginally delivered twins, then from the neonates to a health care worker and other neonates in a neonatal care unit (1). This finding advances our understanding of how extended-spectrum β-lactamase–positive (and, by extension, other antimicrobial drug–resistant or virulent strains) E. coli can spread within the community.

However, the authors’ use of the term infection for the asymptomatic colonization that was observed, including in the mother (who had asymptomatic bacteriuria), is potentially misleading. This term could perpetuate a line of thinking that is all too common among clinicians and leads to unnecessary antimicrobial drug use, thereby ironically aggravating the problem of antimicrobial drug resistance.

Although the first paragraph of their report implicitly acknowledges the distinction between infection and colonization, the rest of the report (including the abstract) uses the terms infection or infected interchangeably with colonization or colonized. Examples include “Subsequently, infection spread by healthcare worker contact with other neonates,” “a healthcare worker also was infected,” and “a urinary tract infection developed....”

One wonders why, in the absence of genitourinary symptoms, the (postpartum) mother’s urine was cultured and why the positive culture prompted antimicrobial drug therapy. This seeming misinterpretation by the mother’s providers of what probably was a harmless colonization state as representing acute disease, and their all too typical response (i.e., antimicrobial drug therapy), are to be discouraged (2). More cautious use of terminology, to emphasize the distinction between colonization and infection (which have radically different therapeutic implications), may help refine clinicians’ thinking and practice in this regard, thereby promoting improved antimicrobial drug stewardship and slowing the antimicrobial drug resistance epidemic.

James R. Johnson
Author affiliation: Author affilation: Veterans Affairs Medical Center, Minneapolis, Minnesota, USA


  1. Tschudin-Sutter S, Frei R, Battegay M, Hoesli I, Widmer AF. Extended-spectrum β-lactamase–producing Escherichia coli in neonatal care unit. Emerg Infect Dis. 2010;16:175860.PubMed
  2. Nicolle LE, Bradley S, Colgan R, Rice JC, Schaeffer A, Hooton TM. Infectious Diseases Society of America Guidelines for the diagnosis and treatment of asymptomatic bacteriuria. Clin Infect Dis. 2005;40:64354. DOIPubMed

Suggested citation for this article: Johnson JR. Extended-spectrum β-lactamase–producing Escherichia coli in neonatal care unit [letter]. Emerg Infect Dis [serial on the Internet]. 2011 Jun [date cited].

DOI: 10.3201/eid1706.101868

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In Response: We thank James Johnson for the issue that he has raised in his letter (1). We agree that distinction of the terms colonization and infection is crucial to prevent misinterpretation of clinical findings and subsequently unnecessary antimicrobial drug use. The outbreak occurred in the hospital; therefore, definitions of nosocomial infections were used throughout the article (2).

Nosocomial urinary tract infection is defined by the Centers for Disease Control and Prevention as asymptomatic bacteriuria or symptomatic infection (urinary tract infection–symptomatic urinary tract infection; (3,4). Therefore, the term nosocomial urinary tract infection in our report is correct. However, we agree with the author that the term asymptomatic bacteriuria is less than optimal and it was removed when we submitted our report. We agree that the term infection is misleading for describing spread to health care workers and that colonization should have been used. However, the article clearly states that invasive infection did not occur in any of the neonates or health care workers found to be colonized. In addition, the focus of the article was to describe the mode of transmission rather than the distinction between colonization and infection.


  1. Johnson JR. Extended-spectrum β-lactamase–producing Escherichia coli in neonatal care unit. Emerg Infect Dis. 2011;17:11534. DOIPubMed
  2. Tschudin-Sutter S, Frei R, Battegay M, Hoesli I, Widmer AF. Extended-spectrum β-lactamase–producing Escherichia coli in neonatal care unit. Emerg Infect Dis. 2010;16:175860.PubMed
  3. Garner JS, Jarvis WR, Emori TG, Horan TC, Hughes JM. CDC definitions for nosocomial infections, 1988. Am J Infect Control. 1988;16:12840. DOIPubMed
  4. Horan TC, Andrus M, Dudeck MA. CDC/NHSN surveillance definition of health care-associated infection and criteria for specific types of infections in the acute care setting. Am J Infect Control. 2008;36:30932. DOIPubMed

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