Abstract

DETECTION AND ANTIBIOTIC SENSITIVITY TESTING OF BRUCELLA SPECIES

Apexa Suryawanshi and Dr. Rajashree Gandge*

ABSTRACT

Infection with Brucella spp. continues to pose a human health risk globally despite strides in eradicating the disease from domestic animals. The timely and accurate diagnosis and treatment of human brucellosis had been challenge for clinicians because of its non-specific clinical features. Surveillance of disease or identifying etiology is a key element for management of prevention and control program. Therefore, the present study was designed to detect human brucellosis in occupationally exposed humans to infected animals or their products and to study antibiogram of Brucella spp. for detection of emergence of resistance and to find out the suitable antibiotic for treatment of brucellosis. A total of 205 sera and 100 blood samples from animal handlers, farmers, milkers and practicing veterinarians from different parts of Konkan and Western Maharashtra region were processed. Overall seroprevalence of human brucellosis was found to be 16.58%, in a total of 205 sera samples tested by RBPT and STAT. Seroprevalence of brucellosis was found higher in humans from Western Maharashtra region (23.52%) as compared to Konkan region (9.09%). Only 4 Brucella isolates (6.6%) could be recovered from total 60 (22 seropositive + 38 seronegative) human whole blood samples attempted for isolation of Brucella spp. employing biphasic media. Out of 4 Brucella spp. isolates recovered, 3 were identified as Brucella abortus and 1 could not be identified upto its species level. Antibiotic susceptibility test didn’t show development of drug resistance amongst Brucella spp. and isolates were found sensitive to tetracycline, doxycycline and cephotaxim. PCR assays was carried out using six different primers for detection of Brucella isolates at their genus and species level. The PCR using BCSP31 (223 bp and 428 bp), DNAJ/BM (503 bp) and DNAJ/AB (388 bp) primers were proved useful in confirming Brucella organisms at genus level. Whereas, IS711/AB PCR produced abortus specific (Biotype1, 2, 4) amplification (498 bp) confirming the isolates as B. abortus. None of 4 isolates showed B. melitensis specific amplification in IS711/BM PCR. Direct detection of brucellosis by DNAJ/BM PCR from 100 human blood samples revealed amplification product of 503 bp in 48% humans. PCR assays were found to be most sensitive followed by serological and cultural methods in detection of human brucellosis. Although, previous reports show prevalence of Br. melitensis in human brucellosis; in present study Br. abortus was found to be predominant species existed in chronic or subclinical form of occupationally exposed human population.

Keywords: Bacterial isolation, Brucella abortus, Brucella melitensis, Human brucellosis, PCR, Serology.