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Alanine esters of enterococcal lipoteichoic acid play a role in biofilm formation and resistance to antimicrobial peptides.

ABSTRACT: Enterococcus faecalis is among the predominant causes of nosocomial infections. Surface molecules like d-alanine lipoteichoic acid (LTA) perform several functions in gram-positive bacteria, such as maintenance of cationic homeostasis and modulation of autolytic activities. The aim of the present study was to evaluate the effect of d-alanine esters of teichoic acids on biofilm production and adhesion, autolysis, antimicrobial peptide sensitivity, and opsonic killing. A deletion mutant of the dltA gene was created in a clinical E. faecalis isolate. The absence of d-alanine in the LTA of the dltA deletion mutant was confirmed by nuclear magnetic resonance spectroscopy. The wild-type strain and the deletion mutant did not show any significant differences in growth curve, morphology, or autolysis. However, the mutant produced significantly less biofilm when grown in the presence of 1% glucose (51.1% compared to that of the wild type); adhesion to eukaryotic cells was diminished. The mutant absorbed 71.1% of the opsonic antibodies, while absorption with the wild type resulted in a 93.2% reduction in killing. Sensitivity to several cationic antimicrobial peptides (polymyxin B, colistin, and nisin) was considerably increased in the mutant strain, confirming similar results from other studies of gram-positive bacteria. Our data suggest that the absence of d-alanine in LTA plays a role in environmental interactions, probably by modulating the net negative charge of the bacterial cell surface, and therefore it may be involved in the pathogenesis of this organism.

SUBMITTER: Fabretti F

PROVIDER: S-EPMC1489678 | biostudies-literature | 2006 Jul

REPOSITORIES: biostudies-literature

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Alanine esters of enterococcal lipoteichoic acid play a role in biofilm formation and resistance to antimicrobial peptides.

Fabretti Francesca F Theilacker Christian C Baldassarri Lucilla L Kaczynski Zbigniew Z Kropec Andrea A Holst Otto O Huebner Johannes J

Infection and immunity 20060701 7

Enterococcus faecalis is among the predominant causes of nosocomial infections. Surface molecules like d-alanine lipoteichoic acid (LTA) perform several functions in gram-positive bacteria, such as maintenance of cationic homeostasis and modulation of autolytic activities. The aim of the present study was to evaluate the effect of d-alanine esters of teichoic acids on biofilm production and adhesion, autolysis, antimicrobial peptide sensitivity, and opsonic killing. A deletion mutant of the dltA ...[more]

PMID: 16790791

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Project description:Staphylococcus aureus infections represent the major cause of titanium based-orthopaedic implant failure. Current treatments for S. aureus infections involve the systemic delivery of antibiotics and additional surgeries, increasing health-care costs and affecting patient's quality of life. As a step toward the development of new strategies that can prevent these infections, we build upon previous work demonstrating that the colonization of catheters by the fungal pathogen Candida albicans can be prevented by coating them with thin polymer multilayers composed of chitosan (CH) and hyaluronic acid (HA) designed to release a ?-amino acid-based peptidomimetic of antimicrobial peptides (AMPs). We demonstrate here that this ?-peptide is also potent against S. aureus (MBPC?=?4??g/mL) and characterize its selectivity toward S. aureus biofilms. We demonstrate further that ?-peptide-containing CH/HA thin-films can be fabricated on the surfaces of rough planar titanium substrates in ways that allow mammalian cell attachment and permit the long-term release of ?-peptide. ?-Peptide loading on CH/HA thin-films was then adjusted to achieve release of ?-peptide quantities that selectively prevent S. aureus biofilms on titanium substrates in vitro for up to 24?days and remained antimicrobial after being challenged sequentially five times with S. aureus inocula, while causing no significant MC3T3-E1 preosteoblast cytotoxicity compared to uncoated and film-coated controls lacking ?-peptide. We conclude that these ?-peptide-containing films offer a novel and promising localized delivery approach for preventing orthopaedic implant infections. The facile fabrication and loading of ?-peptide-containing films reported here provides opportunities for coating other medical devices prone to biofilm-associated infections. STATEMENT OF SIGNIFICANCE: Titanium (Ti) and its alloys are used widely in orthopaedic devices due to their mechanical strength and long-term biocompatibility. However, these devices are susceptible to bacterial colonization and the subsequent formation of biofilms. Here we report a chitosan and hyaluronic acid polyelectrolyte multilayer-based approach for the localized delivery of helical, cationic, globally amphiphilic ?-peptide mimetics of antimicrobial peptides to inhibit S. aureus colonization and biofilm formation. Our results reveal that controlled release of this ?-peptide can selectively kill S. aureus cells without exhibiting toxicity toward MC3T3-E1 preosteoblast cells. Further development of this polymer-based coating could result in new strategies for preventing orthopaedic implant-related infections, improving outcomes of these titanium implants.

Dataset Information

Alanine esters of enterococcal lipoteichoic acid play a role in biofilm formation and resistance to antimicrobial peptides.

Publications

Alanine esters of enterococcal lipoteichoic acid play a role in biofilm formation and resistance to antimicrobial peptides.

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