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Health Surveillance and Disease Management / Communicable Diseases / Antimicrobial Resistance

Recommendations of an Expert Committee: Performance Evaluation Standards for the Kirby-Bauer Antibiogram (Areas of Inhibition or Interpretation)

(Santiago, Chile, 24–26 February 2003)


Full Text (12 pp, PDF, 149 Kb)
- Introduction
- The Expert Committee's Objectives
- Discussion Summary
- Reports
- General Considerations
- Evaluation Methods
- EvaluatioN
- General Report to be Sent to the Participating Laboratories
- Individual Report
- - Summary of Activities 1996–2003
- Appendix 2: List of Participants

PAHO Antimicrobial Resistance Page

- WHO Drug Resistance Page
- WHO Pharamaceutical Products Page


  • Define and document the standards that will be applied to the performance evaluation of laboratories participating in the Latin American Network for Monitoring Antimicrobial Resistance.
  • Document the basic quality control standards for the laboratories that participate in the national surveillance networks.
  • Draft recommendations for maintaining performance quality in all participating countries.


In 1995, due to the regional alert on the importance of emerging and reemerging diseases, which include resistance to antibiotics, the Pan American Health Organization intensified its activities in this area. A network was developed for monitoring susceptibility to antibiotics for isolated Salmonella spp, Shigella spp, and Vibrio cholerae. These three species are important etiologic agents of diarrheal diseases that may require antibiotic treatment. Their importance transcends individual medical aspects, since epidemics make them a public health problem. Furthermore, the importance of food contamination, sometimes at the source, due to the infection of farm animals, transforms an individual medical problem into an epidemiological problem with serious economic and social implications. The same thing occurs when these etiologic agents cause outbreaks in countries that obtain resources from tourism. This is the origin of a problem with a much broader economic and political impact than the impact of the original medical problem.

The surveillance network for etiologic agents of enteric diseases, sponsored by PAHO, commenced operations in 1996 with the participation of the national reference laboratories (NRLs) of Argentina, Brazil, Chile, Colombia, Costa Rica, Mexico, Peru, and Venezuela. Each of these laboratories became the head of a local network made up of the thousands of microbiology testing laboratories in the Region. In the end, isolation, identification, and determination of the sensitivity to antibiotics of the species subject to surveillance depend on the activities of those laboratories.

The participating countries concluded that, in order to obtain reliable results, it would be necessary to improve quality assurance for the internal practices of each laboratory and to establish a system to allow periodic evaluation of the performance of the national reference laboratory and the laboratory network in every country. Hence, the participating countries agreed that their contribution to the network would be contingent on the national laboratories exercising surveillance according to principles of quality assurance that guarantee the accuracy of the results obtained. Those results would ensure greater rationality in the empirical treatment of individual cases and potential control measures important to the community.

The National Laboratory for Enteric Pathogens (LNPE) in Canada agreed to serve as the organizing laboratory of the system, which laboratories in six Caribbean countries subsequently joined: Bahamas, Barbados, Jamaica, Saint Lucia, Trinidad and Tobago in 1998, and Cuba in 1999. With the support of the US Agency for International Development (USAID), six more Latin American countries were also added to the network in 1999: Bolivia, Ecuador, El Salvador, Guatemala, Nicaragua, and Paraguay.

The countries participating in the network agreed to support their respective national reference laboratory. The NRLs, in turn, is the head of the network that compiles national information identifying the species isolated and their sensitivity to antibiotics. Furthermore, the NRL oversees the application of quality assurance principles at each network laboratory through evaluation visits and is also responsible for evaluating each laboratory's performance. In this way, the information can be used to the extent that it is reliable.

Other community species were subsequently included in the network's surveillance: Streptococcus pneumoniae (invasive), Haemophilus influenzae (invasive) Neisseria meningitidis, Escherichia coli (urinary infection), and species isolated in hospital-acquired infections such as Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter spp, Enterococcus spp (E. faecalis and E. faecium), Klebsiella spp and Enterobacter spp. The performance evaluation system for monitoring these bacteria is the responsibility of the National Institute of Infectious Diseases (Instituto Nacional de Enfermedades Infecciosas / INEI) in Argentina. Appendix 1 gives a list of the principal activities carried out by the network that monitors resistance to antimicrobial drugs.

Evaluating surveillance activities in each country depends on expanding the geographical scope of the activities; increasing the number of participating laboratories (sentinel centers); increasing the number of isolates; improving the results of the international performance evaluation; the availability and dissemination of the information locally, nationally and regionally; and the percentage of agreement between the results of the network laboratories in each country and the national reference laboratory. (A summary of activities to date is provided in Appendix 1.)

Concerning the percentage of agreement between the results of the laboratories in each national network and the results from the corresponding national reference laboratory, the need to define and reach an agreement on the standards that will be applied in the performance evaluation became apparent. For this purpose an Expert Committee was formed to make recommendations to be presented at the annual meeting of the Latin American Network in May 2003. The Expert Committee met in Santiago, Chile, from 24 to 26 February 2003 and was made up of the participants that appear in Appendix 2.