Biotype identification and epidemiological analysis of twenty-four Brucella strains

Abstract

Objective To identify the biotype and analyze the epidemiological characteristics of twenty-four Brucella strains from the primary hospitals in Guangdong Province. Methods The twenty-four Brucella strains, collected from Oct. 2009 to Oct. 2015, were identified by routine biochemical methods, VITEK 2 COMPACT automatic microbial identification analyzer, 16S rRNA gene sequencing and biology phenotype based on serological and bacteriophages lysis test. The etiology was analyzed based on clinical data, biotypes of the isolates and other clinical information. Results All of the twenty-four strains were Gram-negative coccobacilli, including two strains of Brucella suis biotype Ⅱ, four strains of Brucella melitensis biotype I and eighteen strains of Brucella melitensis biotype Ⅲ. By GN card of VITEK 2 COMPACT automatic microbial identification analyzer, one strain was mistaken as Bordetella bronchiseptica and two strains were mistaken as Ochrobaetrum anthropi. The 16S rRNA gene sequencing showed they were high homology to Ochrobactrum intermedium and Ochrobaetrum anthropi, which completely excluded the possibility of Bordetella bronchiseptica. The clinical data showed that all of the twenty-four patients were adults with an average age of 49.0 years old, men and women were twelve people respectively, with no significant gender differences and no occupational exposure, which presenting a wide and diverse range of nonspecific clinical signs and symptoms, but brucellosis was not aware of by the physician. Conclusion Brucella melitensis biotype Ⅲ is the main pathogen of brucellosis, with the characteristics of sporadic outbreak and occult infection in the primary hospitals in Guangdong Province. Key words: Brucella; Identification; Epidemiology; Analysis