لخّصلي

In developing countries, which their facilities and equipment’s seldom satisfy the needs for suitable culturing, obtaining smears and microscopic observation is their primary laboratory procedure for the diagnosis of TB. Although the sensitivity of acid-fast staining is less than culturing procedures and its sensitivity is also dependent on the technician skill and the use of appropriate approaches, but it is the fastest and the most essential TB diagnosis tool especially for patients whom microbial burden and the risk of transmission are very high or the patients who need rapid onset of therapy [21, 22].

According to 2013 report of WHO, the sensitivity of the identification of pulmonary TB using microscopic smear examination is estimated to be up to 70% [4]. The obvious thing is although there are many diagnostic approaches for TB, WHO still considers microscopic smearing of phlegm as the primary diagnostic approach. So the diagnosis of pulmonary TB is usually made based on clinical symptoms, chest radiography and the result of microscopic smear tests.

The sensitivity of phlegm smear test with Ziehl–Neelsen stain in different studies has been estimated between 20% and 70% requiring at least 105 bacilli in each ml of phlegm for test to become positive [23]. To increase the sensitivity we need to increase the quality of materials, tests and the skill of team to a whole new level.

The simultaneous epidemics of HIV and TB, especially in developing countries and the fact that Ziehl–Neelsen stain is less sensitive in people with HIV infection, caused many studies to be concentrated on enhancing microscopic identification approaches. In developed countries, concentrated smears with FM staining is usually the primary approach. This combination is highly effective for low income countries which have high HIV incidence rates but it needs more funding [24]. EQA (External quality assessment) programs are also needed in order to make sure the sample preparation and result interpretation procedures are well implemented in all laboratory units. For EQA programs to be implemented, we need well educated and specialized co-workers for supervision on the laboratory environment and proof reading the results from every laboratory. Although in order to implement evaluation programs in a given country, region or city, international instructions recommend random choice of one or more smears and using these samples as the criteria for EQA programs in the level of that region [24, 25].

Implementing EQA for microscopic examinations not only reinforce laboratory networks, but it improves the quality of diagnostic procedures for TB in the underlying region.

Systematic evaluation of control programs and result interpretation by a laboratory specialist is the most important component for enhancing the management of TB laboratory networks. But due to the lack of enough time and resources, such evaluations are usually very limited. This approach leads to more efficient and cost-effective use of human resources and shows an appropriate management program in the countries with limited resources.