Virulence factors and other clinically relevant characteristics of Chryseobacterium species

[摘要] English: The genus Chryseobacterium was first proposed in 1994 and consisted of six species, it has since rapidly expanded and currently consists of 36 different species. Most of these species have been proposed within the last 3 years. Bacteria belonging to the genus Chryseobacterium are aerobic, non-sporulating, non-motile, Gram-negative rods which produce a yellow pigment. Chryseobacterium species have been found in a variety of environmental, industrial and clinical surroundings. Several species have already exhibited pathogenic characteristics for different animals and for humans as well. The first aim of this study was to evaluate the potential pathogenesis of 14 Chryseobacterium species by evaluating a variety of known virulence factors (enzymes), to evaluate their antimicrobial resistance patterns as well as to determine their resistance to four commercially available disinfectants. When the production of specific enzymes by the 14 Chryseobacterium species were evaluated, it was found that C. daecheongense, C. joostei, C. shigense, C. soldanellicola, C. taeanense, C. vrystaatense together with C. indologenes which was regarded the standard organism, can be regarded potentially pathogenic. The species most resistant to all of the antimicrobials evaluated, were C. indologenes, C. indoltheticum and C. joostei. The most susceptible to the antimicrobials was C. balustinum. It was also found that it would be best to treat an infection of Chryseobacterium with antimicrobials of the quinolone class or cephem class. The penicillin class would seem to be the least effective. The disinfectant resistance was determined by determining the MIC for each tested disinfectant, with a higher MIC exhibiting more resistance. The species with the highest resistance were C. gleum, C. indologenes and C. joostei. The disinfectants tested were for use either on hard surfaces or on wounds (personal use). From the results obtained disinfectants for use on hard surfaces are more effective than those meant for personal use. In conclusion it can be said that C. gleum, C. indologenes and C. joostei may be regarded as the most pathogenic of the 14 Chryseobacterium species evaluated. Chryseobacterium joostei may be less of a threat as it was first isolated from raw milk, which had not yet undergone pasteurization and as such, is less likely to come into contact with the general population. It would seem that C. gleum and C. indologenes however come into contact with people more often as they have been found in or on ill or wounded individuals on several different occasions. The second aim of the study was to evaluate possible degradation of aflatoxin B1 by the 14 Chryseobacterium species. After statistical analysis, it was concluded that no Chryseobacterium species was able to degrade aflatoxin. This study, however contributed to the knowledge on the significance of these bacteria.

[发布机构] University of the Free State