SubMICs of penicillin and erythromycin enhance biofilm formation and hydrophobicity of Corynebacterium diphtheriae strains

Abstract

Subinhibitory concentrations (subMICs) of antibiotics may alter bacterial surface properties and change microbial physiology. This study aimed to investigate the effect of a subMIC (F MIC) of penicillin (PEN) and erythromycin (ERY) on bacterial morphology, haemagglutinating activity, cellsurface hydrophobicity (CSH) and biofilm formation on glass and polystyrene surfaces, as well as the distribution of cell-surface acidic anionic residues of Corynebacterium diphtheriae strains (HC01 tox " strain; CDC-E8392 and 241 tox + strains). All microorganisms tested were susceptible to PEN and ERY. Growth in the presence of PEN induced bacterial filamentation, whereas subMIC of ERY caused cell-size reduction of strains 241 and CDC-E8392. Adherence to human erythrocytes was reduced after growth in the presence of ERY, while CSH was increased by a subMIC of both antibiotics in bacterial adherence to n-hexadecane assays. Conversely, antibiotic inhibition of biofilm formation was not observed. All strains enhanced biofilm formation on glass after treatment with ERY, while only strain 241 increased glass adherence after cultivation in the presence of PEN. Biofilm production on polystyrene surfaces was improved by F MIC of ERY. After growth in the presence of both antimicrobial agents, strains 241 and CDC-E8392 exhibited anionic surface charges with focal distribution. In conclusion, subMICs of PEN and ERY modified bacterial surface properties and enhanced not only biofilm formation but also cell-surface hydrophobicity. Antibiotic-induced biofilm formation may contribute to the inconsistent success of antimicrobial therapy for C. diphtheriae infections. Penicillin (PEN) and erythromycin (ERY) have long been used as drugs of choice for the eradication of toxin-producing

Sub-inhibitory concentrations of penicillin G induce biofilm formation by field isolates of Actinobacillus pleuropneumoniae

“…Numerous studies have shown that b-lactams below their MIC (e.g. 1/4 and 1/2 MIC) could induce biofilm formation of different bacterial species (Ahmed et al, 2009;Davies et al, 2006;Frank et al, 2007;Gomes et al, 2013;Kaplan, 2011;Mirani and Jamil, 2011;Nucleo et al, 2009;Wu et al, 2014). Our findings demonstrated that 1/2 MIC of penicillin G induced biofilm formation in A. pleuropneumoniae.…”

“…On the other hand, exposing P. aeruginosa to sub-MIC of imipenem resulted in the up-regulation of genes involved in alginate biosynthesis (Bagge et al, 2004). Recently, Gomes et al (2013) demonstrated that sub-MIC of penicillin induced bacterial filamentation, cell-surface hydrophobicity of Corynebacterium diphtheriae and increased biofilm formation. Thus, the purpose of this study was to evaluate the effect of sub-MIC of penicillin G on the biofilm formation by field isolates of A. pleuropneumoniae.…”

“…The biofilm matrix of A. pleuropneumoniae is mainly composed of an extracellular polymer of N-acetyl-D-glucosamine (PGA) (Kaplan et al, 2004). Numerous studies have shown that sub-minimum inhibitory concentrations (sub-MIC) of some antibiotics can affect growth, morphology, surface properties, pathogenicity and biofilm formation (Andersson and Hughes, 2014;Davies et al, 2006;Fonseca and Sousa, 2007;Gomes et al, 2013;Kaplan, 2011;Wu et al, 2014). Specifically, antibiotics at sub-MIC may induce bacterial biofilm.…”

Antibacterial fatty acids destabilize hydrophobic and multicellular aggregates of biofilm in S. aureus

“…Accordingly, Goulter et al 23 also reported a significant correlation between hydrophobicity, attachment and biofilm-formation ability in bacteria. Gomes et al 24 reported that sub-MICs of penicillin and erythromycin enhance cell-surface hydrophobicity and biofilm formation. This particular feature of resistant bacteria has a major role in bacterial survival inside the host.…”

Characterization of Two Component Systems of Lactobacillus casei BL23 and their involvement in stress response

“…Therefore, it has been suggested that biofilm formation upon exposure to subinhibitory concentrations of antibiotics may represent and inducible mechanism of antibiotic resistance (Kaplan, 2011). This antimicrobialinduced biofilm formation would account for the difficulties to eradicate recurrent bacterial infections in clinic diseases (Berditsch et al, 2012;Kaplan et al, 2012;Abdelhady et al, 2013;Gomes et al, 2013).…”