CITATION: O'Brien TF, Stelling JM. 1995. WHONET: a program to monitor local and global spread of resistance.
APUA Newsletter 13(4): 1, 6, 8.

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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 resistance.

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

Tel: 617-732-6803
Fax: 617-732-4144


  1. Hughes VM, Datta N. Conjugative plasmids in bacteria of the "pre-antibiotic" era. Nature 1983;302:725-6.
  2. O'Brien TF, Stelling JM. WHONET: an informational system for monitoring antimicrobial resistance. Emerging Infect Dis 1995;1:66.


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