Avaliação de bactérias viáveis e do ensaio de estabilidade térmica no controle de vacinas B19 contra brucelose comercializadas no Brasil

Abstract

Sixty-seven batches of Brucella abortus S19 commercial vaccines, approved for release by the Ministério da Agricultura, Pecuária e Abastecimento (MAPA) and with expiration dates between March and July 2007, had their viable bacterial counts (VBC) determined at approval, at the expiration month and by the accelerate stability test (AET). Of the tested batches, 74.6% showed VBC ≥ 4.0 x 1010 CFU/dose at the expiration date. There were differences in batches with VBC ≥ 4.0 x 1010 CFU/dose according to the expiration period: 93.1%, 60.0% and 66.7% of vaccines with expiration periods of 12, 18 and 24 months, respectively, showed VBC values equal or higher than recommended. Mean VBC/dose at approval and at expiration were significantly different for vaccines with 18-month expiration period (P<0.01). Only batches with 12-month expiration period showed significant differences between mean AET and mean VBC/dose at expiration (P<0.01). For comparing AET to the number of batches approved at expiration, three cut-offs were simulated: 2.0 x 1010 CFU/dose (PC1), 3.0 x 1010 CFU/dose (PC2) and 4.0 x 1010 CFU/dose (PC3). To 12-month and 18-month expiration period vaccines, only PC1 and PC3, respectively, agreed with the number of batches approved at expiration. However, both cut-offs showed low agreement values, confirmed by low sensitivity, specificity and negative predictive values.