In vitro antimicrobial susceptibility testing of human Brucella melitensis isolates from Ulanqab of Inner Mongolia, China

Abstract

BackgroundBrucellosis is an endemic disease in the Inner Mongolia Autonomous Region of China and Ulanqab exhibits the highest prevalence of brucellosis in this region. Due to the complex nature of Brucellosis, a cure for this disease has proven to be elusive. Furthermore, the reduced susceptibility of Brucella spp. to antimicrobial agents has been reported as a potential cause of therapeutic failure. However, detailed in vitro antimicrobial susceptibility patterns pertaining to Brucella isolates from this region have not yet been published. The aim of this study was to evaluate the antibiotic susceptibility profile of Brucella melitensis clinical isolates from Ulanqab, Inner Mongolia, China.MethodsA total of 85 B. melitesis isolates were obtained from humans in Ulanqab of Inner Mongolia, China; the antimicrobial susceptibility of 85 clinical isolates to nine antibiotics was assessed using the E-test method according to the CLSI (Clinical and Laboratory Standards Institute) guidelines.ResultsAll of the tested isolates were susceptible to minocycline, sparfloxacin, doxycycline, tetracycline, ciprofloxacin, gentamicin and levofloxacin. Resistance to rifampin and cotrimoxazole was observed in 1.0% (1/85) and 7.0% (6/85) of the isolates, respectively. However, rpoB gene mutations were not observed in single isolates exhibiting resistance to rifampin.ConclusionsWe observed that B. melitensis isolates are susceptible to the majority of the tested antibiotics. Furthermore, minocycline and sparfloxacin exhibited extremely high bactericidal effects in relation to the B. melitensis isolates. The sensitivity of commonly used drugs for the treatment of brucellosis should be regularly monitored. To the best of our knowledge, this is the first report of rifampin and cotrimoxazole resistant isolates of B. melitensis in China. In summary, based on the findings from this study, we suggest that antibiotic administration and use should be rationalized to prevent future drug resistance.

Identification, Genotyping and Antimicrobial Susceptibility Testing of Brucella spp. Isolated from Livestock in Egypt

“…Hence, these findings are in agreement with previously published reports from Egypt that clearly showed an increase in antimicrobial resistance in various other human pathogens [37]. Reduced rifampicin susceptibilities in B. melitensis strains were also reported from Iran, Malaysia, China, and Kazakhstan [46,48,63,64,66].…”

“…All B. melitensis and B. abortus isolates in this study were sensitive to chloramphenicol, gentamicin and tetracycline. These findings are comparable to previously published reports in Egypt, China, Qatar and Kazakhstan [46,48,65,66].…”

“…Only one study from Brazil reported reduced antimicrobial sensitivity in brucellae isolated from cattle [62]. However, the emergence of brucellae isolated from humans phenotypically resistant to ciprofloxacin, gentamycin, streptomycin, rifampicin and trimethoprim-sulfamethoxazole was reported in Egypt, Iran, Qatar, China, Norway and Malaysia [46,48,[63][64][65]. Phenotypically rifampicin resistant B. melitensis isolates were also reported from Norway in imported cases from the Middle East, Asia or Africa [45].…”

“…The use of antimicrobial susceptibility testing is the solution for appropriate control and treatment of brucellosis [44,45]. Micro-dilution and/or gradient strip (E-test) methods are used to establish minimum inhibitory concentration (MIC) for antimicrobials [45,46]. PCR assays and the subsequent sequencing of genes associated with resistance are used to identify the genetic bases of resistance [47][48][49].…”

Whole-genome sequencing of rough Brucella melitensis in China provides insights into its genetic features

“…is rpoB , and some results showed that variation in the rpoB gene caused reduced sensitivity to rifampicin [ 37 ]. The latest study showed that some Brucella isolates with no variations in rpoB are resistant to rifampicin [ 38 , 39 ]. In our study, no variations in rpoB of any rough B. melitensis strain were observed.…”