********************************************

Communicable diseases are the most common cause of death in developing countries, and their diagnosis and treatment represent a significant challenge to the health services in those areas. The World Health Organization has long
been actively involved in developing and promoting standard techniques for laboratory investigations of such diseases, a first attempt to standardize susceptibility testing of bacterial pathogens being made in 1960. Following on from this, in 1976, the WHO Expert Committee on Biological Standardization drew up requirements for antibiotic susceptibility testing using the disc method.

At the same time, efforts were being made to introduce quality control into laboratory performance. In 1981, WHO established an International External Quality Assessment Scheme for Microbiology. The laboratories that are involved in this scheme are able to play a leading role in the implementation of national quality assessment schemes at all levels of the health care system.

The present publication brings together and updates the various guidelines produced by WHO over the years on sampling of specimens for laboratory investigation, identification of bacteria, and testing of antimicrobial resistance. The information included is intended to lead to harmonization of microbiological investigations and susceptibility testing, and to improve the quality of laboratories at both central and intermediate levels. It concentrates on the procedures to be followed, rather than the basic techniques of microscopy and staining, which have been described in detail in another WHO publication