Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 6 4 2014 08 15 230 233 EN Hadi Sardarabadi Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran. Mansour Mashreghi Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran. Khadijeh Jamialahmadi Biotechnology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran AND Yazd University, Yazd, Iran. Tahere Dianat Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran. 2015 10 16 Background and Objective: Nanoscopic life forms called Nanobacteria or calcifying nanoparticles (CNP) are unconventional agents. These novel organisms are very small (0.1 to 0.5 microns) and possess unusual properties such as high resistance to heat and routine antimicrobial agents. Nanobacteria are 100 times smaller than bacteria and protected by a shell of apatite, so they could be as candidate for emerging and progress of in vivo pathological calcification. In this study, the inhibitory effect of broad-spectrum antibiotics on growth of these new forms of life has been investigated. Material and Methods: Powdered urinary and kidney stones were demineralized with HCl and neutralized with appropriate buffers and became filtered. Finally suspension was incubated in DMEM medium with Fetal Bovine Serum (FBS) and broad-spectrum antibiotics (100U/ml for penicillin and 100µg/ml for streptomycin) for 60 days. Results: In the presence of broad-spectrum antibiotics, Scanning Electron Micrographs (SEM) showed a spherical shape of these nanobacteria. Also, Energy Dispersive X-ray spectroscopy (EDS) showed a pick for calcium and phosphor. Transmission Electron Microscopy (TEM) results illustrated cover around the nanobacteria. Conclusion: The growth of calcifying nanoparticles after adding the broad-spectrum antibiotics may be due to their apatite hard shells supporting them against penetration of the antibiotics. https://ijm.tums.ac.ir/index.php/ijm/article/view/403 https://ijm.tums.ac.ir/index.php/ijm/article/download/403/180