Evaluation of diagnostic value of tube agglutination, blood culture and real time PCR for diagnosis of brucellosis in patients with acute, chronic and focal complication

Brucellosis caused by bacteria of the genus Brucella is the most common zoonotic disease worldwide. Brucellosis is endemic in many countries including Turkey and is an important public health problem in these areas. Brucellosis affect any organs and systems, so may cause the different clinical manifestations, due to lack of specific clinical signs and symptoms may be confused with many diseases. Its diagnosis, therefore, requires microbiological confirmation by isolation of the germ or demonstration of the presence of specific antibodies. However, the timely and accurate diagnosis of brucellosis continues to challenge clinicians because of the some limitations of conventional microbiological methods. PCR-based assays have been suggested as a useful tool for the diagnosis of brucellosis in recent years. The aim of this study was to evaluate the diagnostic value of tube agglutination, blood culture and real time PCR method for patients of different clinical forms with brucellosis. Fifty six patients with brucellosis, 35 control subjects were included. The diagnosis of disease was established by presence of a compatible clinical picture together with the demonstration of specific antibodies at significant titer by standard tube agglutination (STA) or brucellacapt test. Significant titers were considered to be ?1/160 for STA and ?1/320 for brucellacapt test. Blood culture and real time PCR were used all patients in the study. Sensivity, specificity, positive and negative predictive values (PPV and NPV) of these three methods were calculated. The sensitivity of STA, blood culture and real time PCR were found as 98.1%, 32% and 48.2%, respectively. The specificity and PPV of these three methods were found as 100%. Whereas the sensitivity of SAT test in acute, chronic and localized brucellosis was found as similarly, the sensitivity of blood culture and real-time PCR methods was found to be higher in acute brucellosis. NPV of STA, blood culture and real time PCR were found as 80%, 34.4% and 40.8%, respectively. In all suspected brucellosis patients who STA titer is <1/160, blood culture and real time PCR were negative. In conclusion, since STA is far more sensitive than blood culture and real time PCR, it was concluded that STA is still most useful method for diagnosis of acute, chronic and localized brucellosis.