Part II: Microscopy
preface

Within the framework of National Tuberculosis Programmes the first purpose of bacteriological services is to detect infectious cases of pulmonary tuberculosis, monitor treatment progress and document cure at the end of treatment by means of microscopic examination. The second purpose of bacteriological services is to contribute to the diagnosis of cases of pulmonary and extra-pulmonary tuberculosis.

Standardisation of the basic techniques for tuberculosis bacteriology has so many advantages that it has become an unavoidable need. The absence of standardised techniques complicates the activities of new laboratory services as well as the organisation of existing laboratories into an inter-related network. Standardisation makes it possible to obtain comparable results throughout a country; it facilitates staff training, delegation of responsibilities and the selection of equipment, materials and reagents to be purchased; it also facilitates the evaluation of performance and the establishment of suitable supervision in order to increase efficiency and reduce operational costs.

Standardised techniques and procedures are useful if they meet the needs of - and are prepared in accordance with - prevailing epidemiological conditions and different laboratory levels. These techniques should be simple (to obtain the widest coverage) and should be applicable by auxiliary laboratory workers. At the same time, their sensitivity and specificity must guarantee the reliability of results obtained.

While tuberculosis laboratory services form an essential component of the DOTS strategy for National Tuberculosis Programmes, it is often the most neglected component of these programmes. Furthermore, the escalation of tuberculosis world-wide, driven by the HIV epidemic and aggravated by the emergence of multidrug-resistance, has resulted in renewed concern about safety and quality assurance in tuberculosis laboratories.

The above considerations have led to the preparation of guidelines for laboratory services for the framework of National Tuberculosis Programmes. These guidelines are contained in a series of three manuals, two of which are focused on the technical aspects of tuberculosis microscopy and culture and a third which deals with laboratory management, including aspects such as laboratory safety and proficiency testing. These manuals have been developed for use in low-and middle-income countries with high tuberculosis prevalence and incidence rates. Not only are they targeted to everyday laboratory use, but also for incorporation in teaching and training of laboratory and other health care staff.

Finally, in order to adapt the functioning of bacteriological laboratories to the needs of integrated tuberculosis control programmes, information on control programme activities has been included. It is hoped that the series on laboratory services will enable National Tuberculosis Programmes to draw up national laboratory guidelines as one of their essential components.