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Identification and characterization of a soil isolate of Chromobacterium violaceum from Egypt with potential to cause disease

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1Yasser M. Ibrahim, 1.2Ahmed M. Abouwarda, 1Nouran H. Assar*
1Department of Microbiology, General Division of Basic Medical Sciences, National Organization for Drug Control and Research (NODCAR), Giza, 12611, Egypt
2Department of Biology, Faculty of Science and Arts-Khulais, Jeddah University, Saudi Arabia


Background: Chromobacterium violaceum (C. violaceum) is a Gram-negative bacterium mainly held to be a harmless saprophyte and only known as a biosensor strain for quorum sensing studies. However, the emergence of C. violaceum as an opportunistic pathogen is evident. In the present study, we aimed to isolate C. violaceum from soil and to test the ability of the isolates to cause infection in a murine model. Methodology: C. violaceum strain YM1 was isolated from soil using rice grains enrichment method. We identified the bacterium based on its biochemical characteristics using API 20NE as well as Vitek2. The identity of the bacterium was further confirmed on the molecular basis by phylogenetic analysis of the 16S rRNA gene sequence (GenBank accession number: MK660325). We then tested the pathogenicity of strain YM1 in a murine infection model. Results: Identification of strain YM1 revealed that it was closely related to the type strain C. violaceum ATCC 12472. Infectious doses of 104-108 cfu of YM1 were able to cause disease in mice when introduced via the intraperitoneal route. Furthermore, we provide experimental data on the antibiotic resistance phenotype of the soil isolate. Strain YM1 was resistant to multiple antibiotics to which the reference strain was susceptible. Fortunately, strain YM1 was found susceptible to fluoroquinolones; ciprofloxacin, levofloxacin, and norfloxacin. Conclusion: Here, we report on the potential clinical significance of soil isolates of C. violaceum that could be pathogenic despite their free-living style. Data presented here suggest that it is necessary to recognize C. violaceum as a suspected pathogen especially in conditions involving skin injury associated with soil.

About EJMM

The Egyptian Journal of Medical Microbiology EJMM  ISSN Print 1110-2179 - ISSN Online: 1110-2179, The official publication of Egyptian Society of Medical Microbiology

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