Background and Objectives: Bacterial agents are commonly accepted as the main etiology of endodontic infections. A significant proportion of oral bacteria cannot be cultured using existing methods. Since diversity and abundance of bacterial species are different in different populations, the present study was aimed to identify effective microorganisms in persistent endodontic infections in Iranian patients based on culture and molecular biology methods using sequence analysis of 16S rDNA gene. Materials and Methods: Thirty patients with previous failure of endodontic treatment were enrolled in the study. After isolation and disinfection of the tooth surrounding area with 3% sodium hypochlorite and 30% hydrogen peroxide, sampling from the root canals was carried out using two sterile Hedstrom files and two sterile paper points, and then the specimens were transferred to the microbiology laboratory in thioglycolate transport medium so that they undergo aerobic-anaerobic culture, PCR, and 16S rDNA gene sequencing. Results: Of 30 patients (15 women and 15 men), 15 patients had radiographic lesions smaller than 5 mm and other 15 pa- tients had radiographic lesions larger than 5 mm. The mean age of patients was 40.20 ± 13.76 years. A total of 26 patients were asymptomatic. Only four patients had clinical signs such as pain and percussion sensitivity and Tannerella forsythia was the most common bacterium found in this group of patients. 13 bacterial species were found in 11 different genus, one virus strain and one fungus strain. From 30 studied specimens, Enterococcus faecalis was the most common microorganism with prevalence rate of 63.63%. Conclusion: This study showed the type and prevalence of effective bacteria in secondary/persistent endodontic infections in Iranian patients. E. faecalis is the most commonly found microorganism in Iranian patients

Context: Brucellosis represents a zoonotic bacterial disease, caused by a gram negative bacterium called Brucella. Between the diverse species of this bacteria, B. melitensis, B. abortus, B. suis and B. canis consist the main causes of the disease in humans.More than half a million new cases of Brucellosis are reported annually. Consequently, brucellosis is a remarkable threat for the health of society. Because of the multiple nonspecific clinical signs of this infection, such as fever (60% of cases), night sweating, insomnia and anorexia, which are similar to other diseases, the detection of brucellosis is time-consuming and needs more scrutiny. Evidence Acquisition: Blood culture is considered the gold standard for the detection of brucellosis and the sensitivity of this test in the acute form is high. However, for the chronic type of disease, it is remarkably low, in addition, in some cases, it needs long reaction times. Nevertheless, today, some kinds of tests like automatic culturing system and serological methods, such as Rose Bengal (RB) test, serum agglutination test (SAT), 2-mercaptoethanol (2ME) and coombs, which are operated based on agglutination, are useful for the problems mentioned earlier. Conclusion:Although serological methods are common for the diagnosis of brucellosis, false results are observable for several methods, such as the SAT method. Tests like the enzyme-linked immunosorbent assay (ELISA), for the screening of specific traits, although confirmed, have their advantages and defects. The lateral flow assay (LFA) shows promising evidence to be effective in the diagnosis of brucellosis. The polymerase chain reaction (PCR) is more prevalent than other common tests, according to sensitivity and fast answering potency in case of molecular diagnosis. Also, PCR is proper for patients' follow-up during the period of treatment and crimination of relapse by this method is easier compared to others.

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