Pseudomonas aeruginosa Biofilm Lung Infection in Cystic Fibrosis: The Challenge of Persisters

Abstract

Pseudomonas aeruginosa lung infection is difficult to eradicate due to the multiple (intrinsic and acquired) antibiotic resistance of bacteria and to their ability to produce a thick biofilm. Antibiotic treatment is hampered by poor antibiotic diffusion, efflux pump overexpression and the development of a persistent subpopulation with low metabolic activity. This is a cause for special concern in Cystic Fibrosis (CF) patients, where P. aeruginosa lung infection is the chief cause of morbidity and mortality. Combined tobramycin-ciprofloxacin treatment is routinely adopted due to the low frequency of resistant strains and its ostensible ability to control the infection. Nevertheless, symptoms usually recur, mainly due to the antibiotic persisters, which are difficult to detect in routine cultural microbiological assays. This chapter describes the issues involved in the microbiological diagnosis of P. aeruginosa lung infection in CF patients and the possible role of subinhibitory antibiotic concentrations in persister development and infection recurrence.

Mucoid Coating Provides a Growth Advantage to Pseudomonas aeruginosa at Oil–Water Interfaces

“…Pseudomonas aeruginosa is a pathogenic Gram-negative bacterium frequently associated with recurrent CF infections. − Under anaerobic conditions, P. aeruginosa overproduces the extracellular polysaccharide (EPS) materials like alginate, which enables the microbe to persist in the respiratory tracts of CF patients. , This phenotypic change, referred to as the mucoid switch, ,, occurs in the later stage of the disease. , In addition to promoting cell adaptation under hypoxic conditions, this phenotypic switch contributes to bacterial survival through the secretion of a thick EPS matrix that shields against phagocytosis. , Moreover, the mucoid phenotype provides a higher resistance to antimicrobials compared to the nonmucoid cells. − In fact, the mucoid switch is well-recognized as a defense mechanism of many microorganisms during pathogenesis and environmental stress. ,− …”

Medical Scope of Biofilm and Quorum Sensing during Biofilm Formation: Systematic Review

“…The majority of P. aeruginosa infections acquired in hospitals are not always curable, while antibiotic therapy frequently reduces illness symptoms. P. aeruginosa biofilms, which serve as reservoirs for disease recurrence, are primarily to blame for the lack of a full cure [49]. The elements of biofilms, such as alginate, the main polysaccharide in the P. aeruginosa matrix, are virulence factors in addition to serving as disease reservoirs.…”