Mansour Kargarpour Kamakoli - Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran ۲-Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran
Sharareh Khanipour - Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran ۲-Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran
Morteza Masoumi - Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran ۲-Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran
Hasan Ghajavandi - Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran ۲-Microbiology Research Center (MRC), Pasteur Institute of Iran, Tehran, Iran

Background and Aim:One of the main topics about tuberculosis (TB) is mixed (polyclonal) infections. MIRU-VNTR is the best and most widely accepted method for detecting polyclonal infections in TB. Many studies have shown that polyclonal infections in TB is well detected in the sputum samples by the MIRU-VNTR method. Despite the limitations of using sputum samples in many laboratories, setting up MIRU-VNTR directly on smear slide can be useful. The aim of the present study was to investigate the ability to diagnose mixed infections on the smear slide by MIRU-VNTR.Methods:Of 14 clinical specimens, Ziehl–Neelsen-stained microscopic slides were prepared. The PCR on smear slide, their clinical specimens and their respective cultures was performed to amplify a standard set of 24 MIRU-VNTR loci.Results:According to 24 loci MIRU-VNTR analysis, the rate of polyclonal infections in the smear slides was 42.85%. On the other hand, the rate of the polyclonal infections in their respective clinical specimens was 8/14 (57.1%). Intriguingly, in their corresponding cultures 7.14% (1/14) mixed infection was observed.Conclusion:Smear slides are a safe system for transmitting clinical specimens between the reference and environmental labs. In countries with high rate of mixed infections and limited resources, the diagnosis of mixed infections can be so crucial because of its significant effect on TB treatment. We have clearly shown that performing MIRU-VNTR directly on smear slides can detect mixed infections conveniently.

Tuberculosis; MIRU-VNTR; Smear slide; Polyclonal infections; Resource-limited setting