AUTHOR=Liang Jinglong , Huang Teng Yi , Mao Yuzhu , Li Xuejie 

TITLE=Biofilm formation of two genetically diverse Staphylococcus aureus isolates under beta-lactam antibiotics

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1139753

DOI=10.3389/fmicb.2023.1139753

ISSN=1664-302X

ABSTRACT=<sec><title>Purpose</title><p>Our aim was to evaluate the biofilm formation of 2 genetically diverse <italic>Staphylococcus aureus</italic> isolates, 10379 and 121940, under different concentrations of beta-lactam antibiotics on biomass content and biofilm viability.</p></sec><sec><title>Methods</title><p>Biofilm formation and methicillin resistance genes were tested using PCR and multiplex PCR. PCR was combined with bioinformatics analysis to detect multilocal sequence typing (MLST) and SCC<italic>mec</italic> types, to study the genetical correlation between the tested strains. Then, the crystal violet (CV) test and XTT were used to detect biomass content and biofilm activity. Antibiotic susceptibility was tested using a broth dilution method. According to their specific MIC, different concentrations of beta-lactam antibiotics were used to study its effect on biomass content and biofilm viability.</p></sec><sec><title>Results</title><p>Strain 10379 carried the <italic>icaD</italic>, <italic>icaBC</italic>, and MRSA genes, not the <italic>icaA</italic>, <italic>atl</italic>, <italic>app</italic>, and <italic>agr</italic> genes, and MLST and SCC<italic>mec</italic> typing was ST45 and IV, respectively. Strain 121940 carried the <italic>icaA</italic>, <italic>icaD</italic>, <italic>icaBC</italic>, <italic>atl</italic>, and <italic>agr</italic> genes, not the <italic>aap</italic> gene, and MLST and SCC<italic>mec</italic> typed as ST546 and IV, respectively. This suggested that strains 10379 and 121940 were genotypically very different. Two <italic>S. aureus</italic> isolates, 10379 and 121940, showed resistance to beta-lactam antibiotics, penicillin, ampicillin, meropenem, streptomycin and kanamycin, some of which promoted the formation of biofilm and biofilm viability at low concentrations.</p></sec><sec><title>Conclusion</title><p>Despite the large differences in the genetic background of <italic>S. aureus</italic> 10379 and 121940, some sub-inhibitory concentrations of beta-lactam antibiotics are able to promote biomass and biofilm viability of both two isolates.</p></sec>