Identification and in vitro antimicrobial susceptibility of Brucella species isolated from human brucellosis

Analysis of the Brucella melitensis epidemic in Xinjiang: genotyping, polymorphism, antibiotic resistance and tracing

Brucella spp. are facultative intracellular pathogens that cause zoonosis- brucellosis worldwide. There has been a trend of the re-emergence of brucellosis worldwide in recent years. The epidemic situation of brucellosis is serious in Xinjiang. To analyze the epidemic situation of Brucella spp. in Xinjiang among humans and animals, this study identified 144 Brucella isolates from Xinjiang using classical identification and 16 S rRNA sequencing. MLVA, drug resistance testing, and wgSNP detection were also performed. At the same time, analysis was conducted based on the published data of Brucella isolates worldwide. The results showed that the dominant species was B. melitensis biovar 3, which belonged to GT42 (MLVA-8 typing) and the East Mediterranean lineage. The correlation among isolates was high both in humans or animals. The isolates in Xinjiang exhibited higher polymorphism compared to other locations in China, with polymorphism increasing each year since 2010. No amikacin/kanamycin-resistant strains were detected, but six rifampicin-intermediate isolates were identified without rpoB gene variation. The NJ tree of the wgSNP results indicated that there were three main complexes of the B. melitensis epidemic in Xinjiang. Based on the results of this study, the prevention and control of brucellosis in Xinjiang should focus on B. melitensis, particularly strains belonging to B. melitensis bv.3 GT42 (MLVA-8 typing) and East Mediterranean lineage. Additionally, the rifampicin- and trimethoprim-sulfamethoxazole- resistance of isolates in Xinjiang should be closely monitored to avoid compromising the therapeutic efficacy and causing greater losses. These results provide essential data for the prevention and control of brucellosis in Xinjiang and China. Although the isolates from Xinjiang have significant characteristics among Chinese isolates and can reflect the epidemiological situation of brucellosis in China to some extent, this study cannot represent the characteristics of isolates from other regions.

Prevalence of Brucella melitensis and Brucella abortus aminoglycoside-resistant isolates: a systematic review and meta-analysis

INTRODUCTION

Aminoglycosides are vital antibiotics for treating Brucella infections, because they interfere with bacterial protein production and are often combined with other antibiotics. They are cost-effective, have fewer side effects, and can penetrate biofilms. The prevalence of brucellosis has increased in recent years, increasing the need for effective treatments. In addition, the emergence of multidrug-resistant Brucella strains has highlighted the need for an updated and comprehensive understanding of aminoglycoside resistance. This systematic review aimed to provide a comprehensive overview of the global prevalence of aminoglycoside resistance in B. melitensis and B. abortus.

METHODS

A systematic search of online databases was conducted and eligible studies met certain criteria and were published in English. Quality assessment was performed using the JBI Checklist. A random-effects model was fitted to the data, and meta-regression, subgroup, and outlier/influential analyses were performed. The analysis was performed using R and the metafor package.

RESULTS

The results of this systematic review and meta-analysis suggested that the average prevalence rates of streptomycin, gentamicin, and amikacin resistance were 0.027 (95% confidence interval [CI], 0.015-0.049), 0.023 (95% CI, 0.017-0.032), and 0.008 (95% CI, 0.002-0.039), respectively. The prevalence of streptomycin resistance was higher in the unidentified Brucella group than in the B. abortus and B. melitensis groups (0.234, 0.046, and 0.017, respectively; p < 0.02). The prevalence of gentamicin resistance increased over time (r = 0.064; 95% CI, 0.018 to 0.111; p = 0.007). The prevalence of resistance did not correlate with the quality score for any antibiotic. Funnel plots showed a potential asymmetry for streptomycin and gentamicin. These results suggest a low prevalence of antibiotic resistance in the studied populations.

CONCLUSION

The prevalence of aminoglycoside resistance in B. melitensis and B. abortus was low. However, gentamicin resistance has increased in recent years. This review provides a comprehensive and updated understanding of aminoglycoside resistance in B. melitensis and B. abortus.

Prevalence of Brucella melitensis and Brucella abortus tetracyclines resistance: A systematic review and meta-analysis

INTRODUCTION

Brucellosis is a zoonotic disease that can be transmitted from animals to humans. Brucellosis is caused by bacteria of the genus Brucella, which are typically transmitted through contact with infected animals, unpasteurized dairy products, or airborne pathogens. Tetracyclines (tetracycline and doxycycline) are antibiotics commonly used to treat brucellosis; however, antibiotic resistance has become a major concern. This study assessed the worldwide prevalence of tetracycline-resistant Brucella isolates.

METHODS

A systematic search was conducted in Scopus, PubMed, Web of Science, and EMBASE using relevant keywords and Medical Subject Headings (MeSH) terms until August 13, 2022, to identify relevant studies for meta-analysis. A random effects model was used to estimate the proportion of resistance. Meta-regression analysis, subgroup analysis, and examination of outliers and influential studies were also performed.

RESULTS

The prevalence rates of resistance to tetracycline and doxycycline were estimated to be 0.017 (95% confidence interval [CI], 0.009-0.035) and 0.017 (95%CI, 0.011-0.026), respectively, based on 51 studies conducted from 1983 to 2020. Both drugs showed increasing resistance over time (tetracycline: r = 0.077, P = 0.012; doxycycline: r = 0.059, P = 0.026).

CONCLUSION

The prevalence of tetracycline and doxycycline resistance in Brucella was low (1.7%) but increased over time. This increase in tetracycline and doxycycline resistance highlights the need for further research to understand resistance mechanisms and develop more effective treatments.

The canonical Brucella species-host dependency is changing, however, the antibiotic susceptibility profiles remain unchanged

Brucellosis is a chronic disease caused by Brucella species with a wide range of hosts, from marine mammals to terrestrial species, but with strict host preferences. With the zoonotic character, the prevalence of human brucellosis cases is a reflection of animal infections. This study aimed to identify 192 Brucella isolates obtained from various sources by Bruce-ladder PCR and to determine their antibiotic susceptibilities by gradient diffusion method (E-test). As a result of the PCR, all human isolates (n = 57) were identified as B. melitensis. While 58 (82.9%) of the cattle isolates were identified as B. abortus, 59 (90.8%) of the sheep isolates were identified as B. melitensis. In addition, 12 (17.1%) of the cattle isolates and 6 (9.2%) of the sheep isolates were determined as B. melitensis and B. abortus, respectively. The primary host change behavior of B. melitensis was 1.9 times higher than that of B. abortus. While gentamicin and ciprofloxacin susceptibilities of Brucella isolates were 100%, tetracycline, doxycycline, streptomycin, trimethoprim/sulfamethoxazole and rifampicin susceptibilities were 99%, 99%, 97.4%, 91.7% and 83.9%, respectively. The lowest sensitivity of the isolates was determined against to cefoperazone as 26%. A triple-drug resistance was detected in 1 B. abortus isolate that included simultaneous resistance to cefoperazone, rifampicin, and trimethoprim/sulfamethoxazole. The high susceptibility profiles we found against to antibiotics such as tetracycline, doxycycline gentamicin and ciprofloxacin, used widely in treatment, are encouraging. However, the change in the canonical Brucella species-primary host preference suggests the need to reconsider eradication program, including updating vaccine formulations.

Genotyping of Brucella isolates from animals and humans by Multiple-Locus Variable-number Tandem Repeat Analysis (MLVA)

This study investigates country-wide genotype variations through the genotyping of Brucella strains isolated from domestic ruminants and humans. The Brucella spp. isolated from samples taken from animals and humans were first identified as B. abortus and B. melitensis by real-time PCR, and the MLVA-16 approach was then used for the genotyping of the identified isolates. For the study, 416 Brucella spp. were isolated from aborted fetus samples examined between 2018 and 2021, and 74 Brucella spp. from infected humans. Of the 74 human isolates analyzed, 1.3% were identified as B. abortus and 98.7% (73/74) as B. melitensis. The MLVA-16 typing method revealed 30 clonal groups for B. abortus and 37 clonal groups for B. melitensis from which the dominant genotypes and similarities with human isolates in Türkiye were determined.

Determination of Virulence-Associated Genes and Antimicrobial Resistance Profiles in Brucella Isolates Recovered from Humans and Animals in Iran Using NGS Technology

Brucellosis is a common zoonotic disease in Iran. Antimicrobial-resistant (AMR) Brucella isolates have been reported from different developing countries, posing an imminent health hazard. The objective of this study was to evaluate AMR and virulence-associated factors in Brucella isolates recovered from humans and animals in different regions of Iran using classical phenotyping and next generation sequencing (NGS) technology. Our findings revealed that B. melitensis is the most common species in bovines, small ruminants and camels. B. abortus was isolated only from one human case. Probable intermediate or resistant phenotype patterns for rifampicin, trimethoprim-sulfamethoxazole, ampicillin-sulbactam and colistin were found. Whole genome sequencing (WGS) identified mprF, bepG, bepF, bepC, bepE, and bepD in all isolates but failed to determine other classical AMR genes. Forty-three genes associated with five virulence factors were identified in the genomes of all Brucella isolates, and no difference in the distribution of virulence-associated genes was found. Of them, 27 genes were associated with lipopolysaccharide (LPS), 12 genes were related to a type IV secretion system (virB1-B12), two were associated with the toll-interleukin-1 receptor (TIR) domain-containing proteins (btpA, btpB), one gene encoded the Rab2 interacting conserved protein A (ricA) and one was associated with the production of cyclic β-1,2 glucans (cgs). This is the first investigation reporting the molecular-based AMR and virulence factors in brucellae isolated from different animal hosts and humans in Iran. Iranian B. abortus and B. melitensis isolates are still in vitro susceptible to the majority of antibiotics used for the treatment of human brucellosis. WGS failed to determine classical AMR genes and no difference was found in the distribution of virulence-associated genes in all isolates. Still, the absence of classical AMR genes in genomes of resistant strains is puzzling, and investigation of phenotypic resistance mechanisms at the proteomic and transcriptomic levels is needed.

Proteomics-based screening and antibiotic resistance assessment of clinical and sub-clinical Brucella species: An evolution of brucellosis infection control

Brucellae are intracellular sneaky bacteria and they can elude the host's defensive mechanisms, resulting in therapeutic failure. Therefore, the goal of this investigation was to rapid identification of Brucella species collected from animals and humans in Saudi Arabia, as well as to evaluate their resistance to antibiotics. On selective media, 364 animal samples as well as 70 human blood samples were cultured. Serological and biochemical approaches were initially used to identify a total of 25 probable cultured isolates. The proteomics of Brucella species were identified using the MALDI Biotyper (MBT) system, which was subsequently verified using real-time polymerase chain reaction (real-time PCR) and microfluidic electrophoresis assays. Both Brucella melitensis (B. melitensis) and Brucella abortus (B. abortus) were tested for antimicrobial susceptibility using Kirby Bauer method and the E-test. In total, 25 samples were positive for Brucella and included 11 B. melitensis and 14 B. abortus isolates. Twenty-two out of 25 (88%) and 24/25 (96%) of Brucella strains were recognized through the Vitek 2 Compact system. While MBT was magnificently identified 100% of the strains at the species level with a score value more than or equal to 2.00. Trimethoprim-sulfamethoxazole, rifampin, ampicillin-sulbactam, and ampicillin resistance in B. melitensis was 36.36%, 31.82%, 27.27%, and 22.70%, respectively. Rifampin, trimethoprim-sulfamethoxazole, ampicillin, and ampicillin-sulbactam resistance was found in 35.71%, 32.14%, 32.14%, and 28.57% of B. abortus isolates, correspondingly. MBT confirmed by microfluidic electrophoresis is a successful approach for identifying Brucella species at the species level. The resistance of B. melitensis and B. abortus to various antibiotics should be investigated in future studies.

Investigation of antibiotic susceptibilities of Brucella Strains isolated from various clinical samples in eastern Turkey

Background

Brucellosis is a worldwide zoonotic disease that causes serious public health problems. This study aimed to identify Brucella strains isolated from various clinical samples by conventional and molecular methods and to determine antimicrobial susceptibilities against doxycycline (DOX), streptomycin (STR), ciprofloxacin (CIP) and rifampicin (RIF) by the gradient strip (E test) test method.

Methods

A total of 87 Brucella strains isolated from various clinical specimens between 2004 and 2018 were included in this study. While four of the 87 strains included in the study were identified only at the genus level, the remaining 83 strains were identified at the species level by the Real-Time Multiplex PCR (M-RT-PCR) method and conventional methods were used for biotyping.

Results

According to molecular identification results, 83 strains were identified as B. melitensis by the M-RT-PCR method, with 82 strains identified as Brucella melitensis biovar (bv) 3 and one as B. melitensis bv 1 according to the conventional biotyping method. Among the antibiotics studied, CIP was found to be the most active agent according to the minimum inhibitory concentrations (MIC)₉₀ values. This was followed by DOX and STR, respectively. While all of the isolates were sensitive to CIP, DOX and STR, 18 (20.7%) strains were found to be moderately susceptible to RIF, with the highest values of MIC₅₀ and MIC₉₀.

Conclusions

In our study, all strains were identified as B. melitensis. DOX, STR, CIP and RIF used in the treatment of brucellosis were found to be effective.

The current therapeutical strategies in human brucellosis

Prompt and adequate treatment of human brucellosis continues to be the most important strategy in its management, as eradication of animal brucellosis is not possible so far, and there is no adequate vaccine for humans. The goal of antibrucellar treatment is to alleviate and shorten the symptomatic period and reduce complications, relapses, and chronicity. Contemporary trends in the treatment of human brucellosis are postulated on the ability of Brucellae to persist in host macrophages through the inhibition of phagolysosome fusion and to survive for prolonged periods intracellularly without restricting basic cellular functions. As a result of this and despite satisfactory antibiotic treatment, relapses and therapeutical failures are inevitable to a certain degree. The current principles for the treatment of brucellosis advocate for a long enough treatment duration combined with antimicrobial regimens that possess activity in the intracellular acidic environment. In the future, other antimicrobial agents, immunomodulation, decrease in the intracellular acidic environment, or development of agents that would act on well-defined molecular bacterial targets, might be incorporated to improve the therapeutical effects.

Cell membrane components of Brucella melitensis play important roles in the resistance of low-level rifampicin

Brucella spp. are facultative intracellular pathogens that can persistently colonize host cells and cause the zoonosis- brucellosis. The WHO recommended a treatment for brucellosis that involves a combination of doxycycline, rifampicin, or streptomycin. The aim of this study was to screen rifampicin-resistance related genes by transcriptomic analysis and gene recombination method at low rifampicin concentrations and to predict the major rifampicin- resistance pathways in Brucella spp. The results showed that the MIC value of rifampicin for B. melitensis bv.3 Ether was 0.5 μg / mL. Meanwhile, B. melitensis had an adaptive response to the resistance of low rifampicin in the early stages of growth, while the SNPs changed in the rpoB gene in the late stages of growth when incubated at 37°C with shaking. The transcriptome results of rifampicin induction showed that the functions of significant differentially expressed genes were focused on metabolic process, catalytic activity and membrane and membrane part. The VirB operon, β-resistance genes, ABC transporters, quorum-sensing genes, DNA repair- and replication -related genes were associated with rifampicin resistance when no variations of the in rpoB were detected. Among the VirB operons, VirB7-11 may play a central role in rifampicin resistance. This study provided new insights for screening rifampicin resistance-related genes and also provided basic data for the prevention and control of rifampicin-resistant Brucella isolates.

Brucella spp. are facultative intracellular pathogens that can persistently colonize host cells and cause the zoonosis- brucellosis. The WHO recommended a treatment for brucellosis that involves a combination of doxycycline, rifampicin, or streptomycin. Rifampicin-resistance related genes were screened by transcriptomic analysis and gene recombination method at low rifampicin concentrations and the major rifampicin- resistance pathways in Brucella spp were predicted. The results showed that the VirB operon, β-resistance genes, ABC transporters, quorum-sensing genes, DNA repair- and replication -related genes were associated with rifampicin resistance when no variations of the in rpoB were detected. Among the VirB operons, VirB7-11 may play a central role in rifampicin resistance.

Nanoniosome-encapsulated levoflaxicin as an antibacterial agent against Brucella

A study was conducted to examine the prevalence of brucellosis (in animal farms) in the vicinity of Islamabad and Rawalpindi. A total of 170 milk samples were collected randomly from several farmhouses. The collected milk samples were initially screened by a Brucella selective medium. The bacterial isolates grown on the selective medium were subjected to biochemical identification for further confirmation of Brucella species. Among the tested samples, 28 (16.4%) were found positive for selective medium and 14 (8.2%) were found positive after biochemical confirmation. The antimicrobial susceptibility of several antibiotics performed by the disc-diffusion method did not yield any significant findings. Encapsulating antimicrobial drugs in unilamellar niosomes is an effective approach to treat the endemic infection. In this study, the antimicrobial activity of niosome-encapsulated levofloxacin is compared with free drug. The drug-encapsulating and empty niosomes were synthesized by using two surfactants Tween 80 and Span 40. Niosomal characterization included electron microscopy, dynamic light scattering, and zeta potential. The encapsulation efficiency was found to be 78% and 74% for Span 40 and Tween 80 niosomes, respectively. The antibacterial activity of niosomal levofloxacin was evaluated against the identified Brucella species and the antimicrobial activity of the free drug was increased many folds after encapsulation. In this study, levofloxacin niosomes were successfully synthesized against Brucellosis.

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

Brucellosis is a highly contagious zoonosis worldwide with economic and public health impacts. The aim of the present study was to identify Brucella (B.) spp. isolated from animal populations located in different districts of Egypt and to determine their antimicrobial resistance. In total, 34-suspected Brucella isolates were recovered from lymph nodes, milk, and fetal abomasal contents of infected cattle, buffaloes, sheep, and goats from nine districts in Egypt. The isolates were identified by microbiological methods and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Differentiation and genotyping were confirmed using multiplex PCR for B. abortus, Brucella melitensis, Brucella ovis, and Brucella suis (AMOS) and Bruce-ladder PCR. Antimicrobial susceptibility testing against clinically used antimicrobial agents (chloramphenicol, ciprofloxacin, erythromycin, gentamicin, imipenem, rifampicin, streptomycin, and tetracycline) was performed using E-Test. The antimicrobial resistance-associated genes and mutations in Brucella isolates were confirmed using molecular tools. In total, 29 Brucella isolates (eight B. abortus biovar 1 and 21 B. melitensis biovar 3) were identified and typed. The resistance of B. melitensis to ciprofloxacin, erythromycin, imipenem, rifampicin, and streptomycin were 76.2%, 19.0%, 76.2%, 66.7%, and 4.8%, respectively. Whereas, 25.0%, 87.5%, 25.0%, and 37.5% of B. abortus were resistant to ciprofloxacin, erythromycin, imipenem, and rifampicin, respectively. Mutations in the rpoB gene associated with rifampicin resistance were identified in all phenotypically resistant isolates. Mutations in gyrA and gyrB genes associated with ciprofloxacin resistance were identified in four phenotypically resistant isolates of B. melitensis. This is the first study highlighting the antimicrobial resistance in Brucella isolated from different animal species in Egypt. Mutations detected in genes associated with antimicrobial resistance unravel the molecular mechanisms of resistance in Brucella isolates from Egypt. The mutations in the rpoB gene in phenotypically resistant B. abortus isolates in this study were reported for the first time in Egypt.

Antimicrobial susceptibility of Brucella spp. isolated from Iranian patients during 2016 to 2018

BACKGROUND AND OBJECTIVES

Brucellosis is a widespread zoonotic disease with a high prevalence in both animals and humans. The present study was aimed to evaluate the susceptibility of Brucella strains isolated from human clinical specimens against commonly used antimicrobial agents.

MATERIALS AND METHODS

A total of 360 blood specimens were collected during 2016-2018 and subjected to culture and Brucella spp. identification. The classical biotyping for Brucella isolates was performed according to Alton and coworker's guidelines. Antimicrobials susceptibility test carried out using disk diffusion and minimal inhibitory concentration (MIC) methods.

RESULTS

In this study, sixty B. melitensis strains were isolated from blood samples (16%) and all them belonged to biovar 1. Majority of the tested antibacterial agents, excepting ampicillin-sulbactam had an effective activity against B. melitensis isolates in E-test (MIC) and disk diffusion method. Moreover, probable resistance to rifampin and ampicillin-sulbactam were observed in 60 (100%), 1 (1.7%), 11 (18.4%) and 2 (3.4%) isolates, respectively.

CONCLUSION

Our data suggest that the efficacy of commonly used antibiotics for brucellosis treatment should be regularly monitored. In conclusion, appropriate precaution should be exercised in the context of antibiotic administration to prevent future antibiotic resistance.

Whole-genome sequencing and antimicrobial resistance in Brucella melitensis from a Norwegian perspective

Brucellosis is a rarely encountered infection in Norway. The aim of this study was to explore all Brucella melitensis isolates collected in Norway from 1999 to 2016 in relation to origin of infection and antimicrobial resistance patterns. A total of 23 isolates were analysed by whole-genome sequencing and compared with selected sequences of B. melitensis available from NCBI. Additionally, SNP analysis in antibiotic resistance determining genes was performed. The majority belonged to the East Mediterranean clade (genotype II), while the remaining isolates belonged to the African clade (genotype III). These results indicate that human brucellosis in Norway is related to travels or migration from the Middle East, Asia or Africa, in accordance with results from Germany, Denmark and Sweden. Antibiotic susceptibility patterns were determined by broth microdilution method and/or gradient strip method. All isolates were susceptible for all tested antibiotics, except for rifampicin where phenotypical results indicated resistance or intermediate resistance in all isolates based on broth microdilution method, and in four isolates based on gradient strip testing. In contrast, screening of the rpoB gene did not reveal any mutations in the previously described rpoB "hot spot" regions related to rifampicin resistance, indicating overestimation of resistance based on phenotypical results.

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

Background

Brucellosis 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.

Methods

A 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.

Results

All 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.

Conclusions

We 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.

Control of animal brucellosis: The Malaysian experience

Brucellosis is a zoonotic disease characterized by reproductive failure in animals and undulent fever in humans. In cattle, it is caused by Brucella abortus while in goats by Brucella melitensis, the main cause of brucellosis in humans. Brucellosis in livestock has been associated with importation of animals from breeder herd of unknown disease status. The prevalence of bovine brucellosis Brucella abortus in 2014 ranged between 1% and 2% in Thailand and Indonesia, and 4%-5% in Malaysia and Myanmar. Prevalence of goat brucellosis Brucella melitensis is approximately 1% in Malaysia and Thailand. 'Test-and-slaughter' is the general policy against brucellosis adopted by most ASEAN countries to eradicate the disease. Under this program, the Rose Bengal Plate Test (RBPT) is used as the screening test to identify infected farm/herd while the complement fixation test (CFT) is the confirmatory test. The test-and-slaughter eradication strategy that was implemented since 1979 had managed to keep the prevalence rate to less than 5%, from 3.3% in 1979, 0.23% in 1988, 1% in 1998 and 5% in 2016. The test-and-slaughter program seemed effective in reducing the prevalence of brucellosis but was unable to eradicate the disease due to several factors, which include failure to locate and identify the remaining affected animals and to control their movement, importation of breeder animals from non-brucellosis free countries and lack of participation by the farmers following unreliable test results. To support the eradication policy, research activities since 1980s have suggested combinations of serological tests to improve diagnosis while surveillance should be focused on hotspots areas. The prevalence can be further reduced by strictly sourcing breeder animals from brucella-free areas or countries.

Clinical and Diagnostic Aspects of Brucellosis and Antimicrobial Susceptibility of Brucella Isolates in Hamedan, Iran

Current drug regimens for brucellosis are associated with relatively high rates of therapeutic failure or relapse. Reduced antimicrobial susceptibility of Brucella spp. has been proposed recently as a potential cause of therapeutic failure. The aim of this study was to evaluate the antibiotic resistance pattern of Brucella melitensis clinical isolates by E-test method in Hamadan, west of Iran. In a 15-month period, all patients with suspected brucellosis were enrolled. Blood specimens were collected for diagnosis of brucellosis by BACTEC system and serological tests. Antimicrobial susceptibility of clinical isolates to 7 antibiotics was assessed by the E-test method. One hundred forty-nine patients with brucellosis were evaluated. 38.3% of cultures of clinical samples were positive for BACTEC system, of which 91.2% were associated with a positive serological test result. No significant associations were found between serology and the culture method. All Brucella isolates were susceptible to doxycycline, streptomycin, gentamicin, ciprofloxacin, and moxifloxacin. However, decreased sensitivity to rifampin and trimethoprim-sulfamethoxazole was found in 35.1% and 3.5% of isolates, respectively. Because of the high rates of intermediate sensitivity to rifampin among Brucella isolates, this drug should be prescribed with caution. We recommend restricting the use of rifampin for treatment of brucellosis except as an alternative drug for special situations.

In vitro antimicrobial susceptibility testing of human Brucella melitensis isolates from Qatar between 2014 - 2015

Background

Brucellosis is one of the most common zoonotic disease affecting humans and animals and is endemic in many parts of the world including the Gulf Cooperation Council region (GCC). The aim of this study was to identify the species and determine the antimicrobial susceptibility pattern of Brucella strains isolated from clinical specimens, from Qatar.

Results

We evaluated 231 Brucella isolates. All isolates were identified as B. melitensis. All the isolates were susceptible to doxycycline, tetracycline, streptomycin, gentamicin, trimethoprim / sulfamethoxazole and ciprofloxacin except rifampicin, where 48 % of the strains showed elevated MICs (>1 mg/L). The rifampicin-resistance related hotspots within the rpoB gene were amplified and sequenced using PCR and no rpoB mutations were found in strains with rifampicin MICs of >2 mg/L.

Conclusion

This study identified B. melitensis as the etiological agent of brucellosis in Qatar. No resistant isolates were detected among conventionally used antimicrobial agents.