Science Brucellosis is difficult to diagnose based on clinical symptoms of the disease, which are nonspecific and often atypical signs. 1,2 Therefore, the diagnosis mostly relies on the results of laboratory testing. Culture of the organism is the diagnostic method of choice; however, cultures involve risk of infection and require special precautions in the laboratory. 3,4 An infectious dose for Brucella in humans is 10 to 100 organisms; consequently, diagnostic laboratory personnel who

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... e these organisms are at significant risk of accidental exposure. Brucellosis is one of the most commonly reported laboratory-acquired infections. Current methods of testing cultures for Brucellae are time-consuming and lack sensitivity, particularly in chronic infections. 5, 6 Most laboratories apply serological tests that do not provide suitable sensitivity and specificity for this organism. Enzyme-linked immunosorbent assay (ELISA) methods that detect immunoglobulin G (IgG) are sensitive 7 but have low specificity. 8 Measurement of specific immunoglobulin M (IgM) levels has lower sensitivity than IgG but is more specific. Molecular diagnostic assays minimize the risks associated with handling potentially infectious specimens and increase the sensitivity, specificity, and speed of testing, although some studies have reported only moderate sensitivity (50%) using these methods. 8 However, few laboratories diagnose brucellosis using culture methods because cultures have limited sensitivity, are timeconsuming, and require specially biosafety equipment. 9 Therefore, data on the frequency on Brucella infections are often unreliable. Recently, multiplex polymerase chain reaction (PCR) protocols that overcome these problems have been described. [10] [11] [12] In this study, we used a multiplex ABSTRACT Objective: To determine the sensitivities of various testing methods for diagnosing brucellosis. Methods: The 267 patients in our cohort were suspected to be infected with Brucella and had been referred to a hospital in Mianeh City, Iran. The mean (SD) age was 37.0 (11.3) years for female patients and 37.1 (13.7) years for male patients. All serum specimens from these patients were examined by the standard agglutination test (SAT), Coombs Wright test, 2-mercaptoethanol (2ME) test, enzyme-linked immunosorbent assay (ELISA) for determining levels of immunoglobulin G (IgG) and immunoglobulin M (IgM), and multiplex polymerase chain reaction (PCR). DNA was extracted. Extracted DNA was checked with human PCR-targeting CRP gene-encoding 485 base pair (bp) as an internal control to ensure that the proper extraction method had been used. Specific primers targeting IS 711 were used for Brucellosis melitensis, B abortus, and B suis. Results: Brucellosis was confirmed in 110 patients (58.2% male and 41.8% female) based on applied diagnostic methods and clinical features. Results of ELISA, the SAT, and PCR were positive in 92, 42, and 51 patients, respectively. B abortus and B melitensis were detected in 16 and 35 patients, respectively. B suis was not detected in any of the specimens. Conclusions: All methods tested in our study need to be used to ensure accurate diagnosis of brucellosis, although ELISA displayed the highest level of efficiency. Also, B melitensis showed a higher frequency rate than B abortus in our cohort.