A novel selective medium for the isolation of Burkholderia mallei from equine specimens.
Abstract: Burkholderia mallei is a Gram-negative bacterium that causes glanders, a zoonotic disease, especially in equine populations (e.g. horses, donkeys, and mules). B. mallei usually grows slowly on most culture media, and this property makes it difficult to isolate from clinical specimens. One of the problems is that B. mallei is easily overgrown by other bacteria, especially in animal specimens collected from non-sterile sites. The aim of this study was to develop a new selective agar for the laboratory diagnosis of glanders. We formulated a new agar, named BM agar, to enrich B. mallei growth, but inhibit the growth of other bacteria and fungi based on their antimicrobial profiles. We compared the growth of B. mallei on BM with Xie's and PC agars, the two previously described selective agars for B. mallei. Results: BM agar could sufficiently grow almost all of the tested B. mallei strains within 72 h: only one out of the 38 strains grew scantly after 72 h of incubation. BM agar was further tested with other Burkholderia species and various bacterial species commonly found in the nasal cavities and on the skin of horses. We have found that other Burkholderia species including B. pseudomallei and B. thailandensis can grow on BM agar, but non-Burkholderia species cannot. Furthermore, the specificities of the three selective agars were tested with or without spiking B. mallei culture into clinical specimens of non-sterile sites collected from healthy horses. The results showed that BM agar inhibited growths of fungi and other bacterial species better than PC and Xie's agars. We have also found that growth of B. mallei on BM agar was equivalent to that on 5% horse blood agar and was significantly greater than those on the other two agars (P < 0.05). Conclusions: We believe that BM agar can be used to efficiently isolate B. mallei from mixed samples such as those typically collected from horses and other contaminated environments.
Publication Date: 2019-05-07 PubMed ID: 31064357PubMed Central: PMC6505306DOI: 10.1186/s12917-019-1874-0Google Scholar: Lookup
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Summary
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The research is about the creation of a new culture medium, called BM agar, used for isolating the glanders causing bacteria, Burkholderia mallei, in equine specimens. The novel medium outperforms two existing types of agar, showing superior selectivity and bacterial growth promotion.
Introduction
- Burkholderia mallei is a slow-growing, Gram-negative bacterium that causes glanders, an infectious disease affecting equine populations such as horses, donkeys, and mules.
- It is challenging to isolate this bacteria because it is often overgrown by other species, particularly when collected from non-sterile environments.
- The research aims to create a new selective agar medium for the effective growth and isolation of this bacterium.
Methodology
- The researchers developed a new agar named BM agar specifically to enhance the growth of B. mallei, whilst inhibiting the growth of other bacteria and fungi.
- This agar was compared with two existing selective agars (Xie’s and PC agars) to test the efficiency of B. mallei growth.
- Several Burkholderia species and bacteria commonly found in horse nasal cavities and skin samples were tested on the BM agar.
Results
- The findings demonstrated that virtually all tested B. mallei samples grew sufficiently on BM agar within 72 hours.
- Other types of Burkholderia species such as B. pseudomallei and B. thailandensis also grew on BM, but non-Burkholderia species did not.
- When B. mallei was added to clinical specimens collected from healthy horses, BM agar was more effective in inhibiting the growth of other bacteria and fungi than the Xie’s and PC agars.
- B. mallei growth on BM agar was also proven to be equivalent to 5% horse blood agar, enhancing its prospects for clinical application.
Conclusion
- The results suggested that the novel BM agar can be used to efficiently isolate B. mallei from mixed samples, such as those that are often obtained from horses, and so it contributes to the more effective management of glanders.
Cite This Article
APA
Kinoshita Y, Cloutier AK, Rozak DA, Khan MSR, Niwa H, Uchida-Fujii E, Katayama Y, Tuanyok A.
(2019).
A novel selective medium for the isolation of Burkholderia mallei from equine specimens.
BMC Vet Res, 15(1), 133.
https://doi.org/10.1186/s12917-019-1874-0 Publication
Researcher Affiliations
- Microbiology Division, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan. kinoshita@equinst.go.jp.
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32608, USA. kinoshita@equinst.go.jp.
- Unified Culture Collection, Diagnostic Systems Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, 21702-5011, USA.
- Unified Culture Collection, Diagnostic Systems Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, 21702-5011, USA.
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32608, USA.
- Microbiology Division, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan.
- Microbiology Division, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan.
- Microbiology Division, Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan.
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32608, USA.
MeSH Terms
- Agar
- Animals
- Burkholderia mallei / growth & development
- Burkholderia mallei / isolation & purification
- Culture Media / chemistry
- Glanders / diagnosis
- Glanders / microbiology
- Horses
Conflict of Interest Statement
ETHICS APPROVAL: All experiments were conducted in accordance with ethical and welfare regulations of the Animal care committee of the Equine Research Institute and ethics regarding this study were approved by the committee under the identification number 19–19. CONSENT FOR PUBLICATION: Not applicable COMPETING INTERESTS: The authors declare that they have no competing interest. PUBLISHER’S NOTE: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
References
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