The correlation of agglutination titer with positive blood cultures in brucellosis: A comparison of two study periods.

Brucellosis is an endemic zoonosis in Saudi Arabia. Correlation of Brucella agglutination antibody titer with positive blood culture was performed over 2 time periods (1986 and 1998). At the King Fahad National Guard Hospital we generally consider a titer value of 1:320 or greater as being diagnostic of Brucella. Using this cut-off, the positive predictive value of 39.3% (95% CI=31.5 to 47.6) in the 1986 study increased to 55.7% (95% CI=42.4 to 68.5) in the recent study (P=0.03). This improvement is probably due to parallel improvement in both methodologies.