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Volume 8, Number 4—April 2002


Antimicrobial Use and Antimicrobial Resistance: A Population Perspective

Marc Lipsitch*Comments to Author  and Matthew H. Samore†
Author affiliations: *Harvard School of Public Health, Boston, Massachusetts, USA; †University of Utah School of Medicine, Salt Lake City, Utah, USA

Main Article


Mechanisms by which antimicrobial treatment has direct and indirect effects on resistance

Mechanism (effect of treatment) Relationship between selection for resistance and treatment success Relationship between no./dose of antibiotics and selection Examples Figure
mergence of resistance during treatment
(Da, Ib) (−)c (−) TB, HIV, Pseudomonas aeruginosa, Enterobacter spp. 1a
Reduced transmission of susceptible strains
(I) (+)d (+) May occur for nearly every infection 1b
Increased susceptibility to colonization (D, I,) ?e ? Commensals of skin, intestinal and respiratory tracts 1c
Increased density of colonization in individuals already colonized with resistant organisms, by inhibiting competitors (D,I) ? (+)−? VREf and antianaerobic treatments 1d

c(-)=inverse relationship.
d(+)=positive relationship.
e?=relationship uncertain.
fVRE=vancomycin-resistant Enterococci.

Main Article