Differences in biofilm formation and transcription of biofilm-associated genes among Acinetobacter baumannii clinical strains belonging to the international clone II lineage

Acinetobacter baumannii isolates belonging to international clonal lineage (IC) II are often multidrug-resistant and are the predominant cause of nosocomial outbreaks. While many studies have investigated the genetic and functional basis of antimicrobial resistance of these strains, few have examine...

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Published in:	Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy Vol. 26; no. 7; pp. 693 - 698
Main Authors:	Kishii, Kozue, Hamada, Masakaze, Aoki, Kotaro, Ito, Kengo, Onodera, Joh, Ishii, Yoshikazu, Tateda, Kazuhiro
Format:	Journal Article
Language:	English
Published:	Netherlands Elsevier Ltd 01-07-2020
Subjects:	Acinetobacter baumannii Acinetobacter baumannii - genetics Acinetobacter baumannii - pathogenicity Acinetobacter Infections - microbiology bfmS/R Biofilm formation Biofilms - growth & development csu DNA, Bacterial - genetics DNA, Bacterial - isolation & purification Fimbriae Proteins - genetics Gene Expression Regulation, Bacterial Genes, Bacterial - genetics Humans International clone II Operon - genetics Transcription, Genetic Virulence - genetics Whole Genome Sequencing ST Acinetobacter baumannii csu MLST Biofilm formation bfmS/R IC International clone II
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Summary:	Acinetobacter baumannii isolates belonging to international clonal lineage (IC) II are often multidrug-resistant and are the predominant cause of nosocomial outbreaks. While many studies have investigated the genetic and functional basis of antimicrobial resistance of these strains, few have examined specific virulence characteristics such as biofilm formation or overall pathogenic potential. Here, we analyzed biofilm formation and the associated mechanisms in A. baumannii clinical isolates from Japan belonging to the IC II lineage. Draft whole-genome sequence data for each of the isolates was analyzed to detect biofilm-associated genes, including csu (pili) and bfmS/R (two-component regulatory system), and transcription of these genes was evaluated using reverse transcription quantitative PCR. Biofilm formation was measured by crystal violet staining assay. csu operon genes showed some variation in prevalence among the isolates, with an overall prevalence of 73.7% (14/19). The biofilms formed by csu operon-positive isolates were significantly more mature than those of csu operon-negative isolates, supporting the importance of the csu operon in biofilm formation by A. baumannii. However, there was substantial variation among the csu operon-positive isolates, indicating the influence of other factors in biofilm formation. Furthermore, transcriptional levels of csu operon genes were highly divergent, with comprehensive analysis indicating that regulatory factors other than bfmS/R were involved. Our findings are a first step towards understanding the mechanisms of biofilm formation by A. baumannii IC II strains.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1341-321X 1437-7780
DOI:	10.1016/j.jiac.2020.02.017