Effect of carbon dioxide on broth microdilution susceptibility testing of Brucella spp

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.

Vaccine properties of Brucella melitensis 16MΔwzm and reactivation of placental infection in pregnant sheep

Brucellosis, a worldwide zoonotic disease, is endemic in many developing countries. Besides causing significant economic losses for the livestock industry, it has severe consequences for human health. In endemic regions, small ruminants infected by Brucella melitensis are the main source of human brucellosis. Rev1, the only vaccine currently recommended to control the disease in sheep and goats, has several drawbacks. Rough lipopolysaccharide (R-LPS) mutants have been tested as alternatives, but most lack efficacy. Those in the Wzm/Wzt system responsible for O-polysaccharide export to the periplasm have been proposed as promising vaccine candidates, although to date they have been scarcely investigated in the natural host. In the present work, we studied the biological properties of a 16MΔwzm in-frame deletion mutant, including its safety in pregnant mice and sheep. In mice, 16MΔwzm prevented placental and fetal infections before parturition and protected against B. melitensis and Brucella ovis infections. In sheep, 16MΔwzm was equally safe in lambs, rams, and non-pregnant ewes, inducing some transient Rose Bengal reactions (<7 weeks). The serological reactions occurred earlier and more strongly in pregnant than in non-pregnant ewes and were significantly reduced when conjunctival rather than subcutaneous vaccination was used. In ewes vaccinated at mid-pregnancy, 16MΔwzm was not shed in vaginal discharges during the pregnancy and did not induce abortions/stillbirths. However, some ewes showed a transitory reactivation of infection in placentas and/or milk at parturition, accompanied by a seroconversion in smooth LPS (S-LPS) and/or R-LPS tests. Overall, 16MΔwzm can be considered as a safe vaccine for lambs, rams, and non-pregnant ewes, but its use at mid-pregnancy should be avoided to prevent vaccine dissemination at parturition. If the efficacy results against B. melitensis and B. ovis observed in mice are confirmed by further studies in the natural host, 16MΔwzm could constitute a useful vaccine.

Adaptation of Brucella melitensis Antimicrobial Susceptibility Testing to the ISO 20776 Standard and Validation of the Method

Brucellosis, mainly caused by Brucella (B.) melitensis, is associated with a risk of chronification and relapses. Antimicrobial susceptibility testing (AST) standards for B. melitensis are not available, and the agent is not yet listed in the EUCAST breakpoint tables. CLSI recommendations for B. melitensis exist, but they do not fulfill the requirements of the ISO 20776 standard regarding the culture medium and the incubation conditions. Under the third EU Health Programme, laboratories specializing in the diagnostics of highly pathogenic bacteria in their respective countries formed a working group within a Joint Action aiming to develop a suitable method for the AST of B. melitensis. Under the supervision of EUCAST representatives, this working group adapted the CLSI M45 document to the ISO 20776 standard after testing and validation. These adaptations included the comparison of various culture media, culture conditions and AST methods. A Standard Operation Procedure was derived and an interlaboratory validation was performed in order to evaluate the method. The results showed pros and cons for both of the two methods but also indicate that it is not necessary to abandon Mueller-Hinton without additives for the AST of B. melitensis.

The perspective of antibiotic therapeutic challenges of brucellosis in the Middle East and North African (MENA) countries: Current situation and therapeutic management

Brucellosis is among the most prevalent zoonotic infections in Middle Eastern and North African (MENA) countries, critically impacting human and animal health. A comprehensive review of studies on antibiotic susceptibility and therapeutic regimes for brucellosis in ruminants and humans in the MENA region was conducted to evaluate the current therapeutic management in this region. Different scientific databases were searched for peer-reviewed original English articles published from January 1989 to February 2021. Reports from research organizations and health authorities have been taken into consideration. Brucella melitensis and Brucella abortus have been reported from the majority of MENA countries, suggesting a massive prevalence particularly of B. melitensis across these countries. Several sporadic cases of brucellosis relapse, therapeutic failure, and antibiotic resistance of animal and human isolates have been reported from the MENA region. However, several studies proved that brucellae are still in-vitro susceptible to the majority of antibiotic compounds and combinations in current recommended WHO treatment regimens, e.g. levofloxacin, tetracyclines, doxycycline, streptomycin, ciprofloxacin, chloramphenicol, gentamicin, tigecycline, and trimethoprim/sulfamethoxazole. The current review presents an overview on resistance development of brucellae and highlights the current knowledge on effective antibiotics regimens for treating human brucellosis. This article is protected by copyright. All rights reserved.

Antimicrobial Resistance in Leptospira, Brucella, and Other Rarely Investigated Veterinary and Zoonotic Pathogens

Leptospira, Brucella, and Borrelia are major agents of zoonotic disease, causing high morbidity and, in some cases, significant mortality in humans. For all three genera, prompt diagnosis and appropriate antimicrobial therapy are required to prevent the development of chronic, debilitating illness. Leptospira spp. are intrinsically resistant to several antimicrobial classes; however, there is little evidence in the literature for development of acquired resistance to antimicrobial agents used for clinical treatment of acute leptospirosis. For Brucella infections, there are numerous reports of relapses following therapy, but it is unclear whether this is due to sequestration within infected sites (e.g., bone) or the development of acquired resistance. Brucella have maintained their susceptibility to doxycycline and rifampicin, which in combination remain the most common treatments of brucellosis in humans. In vitro induced point mutations are described as imparting resistance to rifampicin (rpoB) and fluoroquinolones (gyrA). The clinical significance of these mutations is unclear. For Borrelia burgdorferi, although acquired resistance to some antimicrobial agents has been described, resistance due to bacterial persister cells surviving in the presence of antimicrobial, with no apparent increase in the MIC of the organism, have been recently described. Of the remaining veterinary fastidious pathogens, Lawsonia intracellularis is the most interesting from an antimicrobial resistance perspective because it can only be grown in cell culture, making in vitro susceptibility testing challenging. MIC testing has been undertaken on a small number of isolates, and some differences in susceptibility to macrolides have been demonstrated between isolates obtained from different regions.