Biofilm-Associated Infections

Antibiotic Resistance and Novel Therapeutic Strategies

Fengjun Sun; Feng Qu; Yan Ling; Panyong Mao; Peiyuan Xia; Huipeng Chen; Dongsheng Zhou


Future Microbiol. 2013;8(7):877-886. 

In This Article

Biofilm-Associated Infections

Microbial biofilms are highly resistant to antibiotics and host immune defenses. Formation of biofilms by clinically relevant microbial pathogens is at the root of many chronic and recurrent infections, and biofilms have been estimated to account for 80% of all microbial infections in the human body.[4] Biofilm-associated infections are often slow in producing overt symptoms and rarely fatal, although they compromise quality of life; moreover, they can linger for months, years or even a lifetime in one or more locations of human body.[4]

Biofilm-associated infections can be broadly divided into two types: infections associated with indwelling medical devices,[5] and native biofilm infections of host tissues.[6] For the former type, bloodstream or urinary tract infections can be caused by infectious biofilms originally formed on the surfaces of indwelling medical devices, such as central venous catheters, mechanical heart valves, urinary catheters, joint prostheses, peritoneal dialysis catheters, cardiac pacemakers, cerebrospinal fluid shunts, endotracheal tubes, contact lenses, intrauterine devices and dental unit waterlines. In these cases, pathogens may originate from the epithelial flora of patients, healthcare personnel or other sources in the environment, to form infectious biofilms on the surfaces of indwelling medical devices, and subsequently gain access to human organs or tissues via indwelling medical devices inserted into the human body.[5] Native biofilm-associated infections are often chronic, opportunistic infections in otherwise sterile locations of the human body, and mainly include chronic lung infections of cystic fibrosis patients, chronic otitis media, native valve infectious endocarditis, chronic osteomyelitis, chronic rhinosinositis, chronic prostatitis, recurrent urinary tract infection, chronic wounds, dental caries and periodontitis.[6]

Biofilm-associated infections can be caused by a single microbial species or by a mixture of species, with interactions between multiple species increasing their persistence.[7] Pathogens frequently involved in biofilm-associated infections include Gram-positive bacteria (especially streptococci and staphylococci), Gram-negative bacteria (especially Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae) and fungi (especially Candida spp. and Aspergillus spp.). Among them P. aeruginosa and Candida albicans are the representatives of bacterial and fungal pathogens, respectively, which will be repeatedly referred to throughout this review. C. albicans can cause superficial and serious systemic diseases and is recognized as one of the major agents of hospital-acquired infections frequently associated with contamination of indwelling medical devices.[8]P. aeruginosa is an opportunistic pathogen of immunocompromised hosts and can cause native acute and chronic lung infections that result in significant morbidity and mortality, especially in cystic fibrosis patients.[9]