Bacterial biofilms: development, dispersal, and therapeutic strategies in the dawn of the postantibiotic era

Abstract

Biofilm formation constitutes an alternative lifestyle in which microorganisms adopt a multicellular behavior that facilitates and/or prolongs survival in diverse environmental niches. Biofilms form on biotic and abiotic surfaces both in the environment and in the healthcare setting. In hospital wards, the formation of biofilms on vents and medical equipment enables pathogens to persist as reservoirs that can readily spread to patients. Inside the host, biofilms allow pathogens to subvert innate immune defenses and are thus associated with long-term persistence. Here we provide a general review of the steps leading to biofilm formation on surfaces and within eukaryotic cells, highlighting several medically important pathogens, and discuss recent advances on novel strategies aimed at biofilm prevention and/or dissolution.

Figure 1.

Schematic of the extracellular matrix composition in E. coli. Structural components include the EPS molecules colonic acid, cellulose, and PGA (polyglucosamine), which enable intercellular interactions, keeping bacteria in close proximity with each other. eDNA also serves as a connecting agent, as well as a nutritional source. Extracellular organelles such as flagella and CUP (chaperone usher pathway) pili enable bacterial aggregation strengthening the biofilm lattice. Secreted enzymes modify EPS components in response to environmental changes.

Figure 2.

Schematic of the IBC developmental cascade in UPEC (uropathogenic Escherichia coli), accompanied by SEM (scanning electron microscopy) images depicting the distinct morphological changes from attachment and invasion to filamentation and dispersal. (SEM images from Anderson et al. 2003, Hultgren Lab.)

Figure 3.

Schematic outlining the stages in biofilm development and listing the strategies aimed at inhibiting and/or disrupting biofilm formation at specific stages.