WHONET: a program to monitor local and
global spread of resistance
Thomas F O'Brien, MD and John M Stelling, MD
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
Antimicrobial resistance hurts patients. It causes their treatments to fail, their infections to persist or worsen
and some of them to die. Antimicrobial resistance is not a disorder of patients, however, but rather a disorder
of bacterial populations. It would help if we could see these bacterial populations with something like an infra-red
camera that made them selectively visible to us. It would be even more beneficial if the camera recorded bacterial
populations under attack (e.g. those being depleted by exposure to antimicrobials) in red; those surviving attack,
in various colors representing the different kinds of resistant strains that replaced the decimated populations;
and undisturbed populations, long free of antimicrobial exposure, in blue.
As we took aerial photographs of a community with such a camera, we would see people and animals as dense concentrations
of colored spots representing the bacteria lining their skins, mouths and intestines. The spots of many healthy
people in the community might be blue, but some would probably have enough resistant bacteria of one kind or another
to register other colors, and some would be red because they were taking an antimicrobial. The red spots and those
with colors other than blue would be much more concentrated in hospitals, especially intensive care units, and
also in day-care centers and animal feed lots.
Over time we might observe patterns of spread. We might notice that when a red spot begins to fade it tends to
take on the color of a nearby spot, meaning that the person taking an antimicrobial tends to repopulate with the
resistant bacteria of someone nearby. We might get the idea that this is an intricate game in which different types
of resistance (different resistance genes) are spreading selectively from treated person to treated person. We
might begin to sense what the rules are, and how to intervene to curtail spread.
Such pictures from sixty years ago would have had only blue spots. The genes that make bacteria resistant to an
agent emerged one by one after each antimicrobial came into widespread use. These genes began to spread in this
way through the world's interconnecting bacterial populations.(1) Most of the people represented as having resistant
bacteria (spots which are not blue) are, of course, only carrying them. A few are infected; more are in the hospital.
But when someone carrying resistant bacteria does become infected, it is more likely to be with resistant bacteria.
Unfortunately, there is no such camera. There is, however, a remarkable body of information that could give us
a view of the problem. Every day tens of thousands of laboratories in medical centers around the world test the
susceptibility to antimicrobial agents of bacteria from people and animals. Their files contain a wealth of detailed
information which could be used to examine the spread of resistance throughout the world, but they have not been
used to visualize it. The problem is that we have not been able to see these files in ways that would give either
the local medical center or the world the views that they need. The files are secluded in systems designed to report
each result only to that patient's record. They are either paper files too laborious to analyze or electronic computer
files with mutually incompatible formats.
WHONET is a program that has been developed to access those files and visualize them fully.(2) WHONET puts the
test result information from each laboratory into a universal file format mounted on a personal computer at that
center. It does this either by serving as the laboratory's computer reporting system or by translating from an
existing system. It then gives the medical center's staff user-friendly programs for analyzing those test results
in ways that allow them to monitor the spread of resistance in their center and its community. WHONET also enables
any center to encrypt its files for confidentiality and merge them easily with files in the same WHONET format
from other centers. In this way groups of centers may take the initiative to aggregate their databases and examine
them in detail to establish regional, national or global surveillance of the frequency and spread of antimicrobial
To support these initiatives, the World Health Organization (WHO) makes WHONET available at no charge to centers
that wish to use it to monitor resistance locally and/or to participate in collaborative multi-center surveillance.
If interested, please contact the authors:
WHO collaborating Center for Surveillance of Antimicrobial Resistance
Brigham and Women's Hospital
Boston, MA 02115
- Hughes VM, Datta N. Conjugative plasmids in bacteria
of the "pre-antibiotic" era. Nature 1983;302:725-6.
- O'Brien TF, Stelling JM. WHONET: an informational system
for monitoring antimicrobial resistance. Emerging Infect Dis 1995;1:66.