Pseudomonas aeruginosa Cystic Fibrosis isolates of similar RAPD genotype exhibit diversity in biofilm forming ability in vitro

Abstract

BackgroundPseudomonas aeruginosa is considered to grow in a biofilm in cystic fibrosis (CF) chronic lung infections. Bacterial cell motility is one of the main factors that have been connected with P. aeruginosa adherence to both biotic and abiotic surfaces. In this investigation, we employed molecular and microscopic methods to determine the presence or absence of motility in P. aeruginosa CF isolates, and statistically correlated this with their biofilm forming ability in vitro.ResultsOur investigations revealed a wide diversity in the production, architecture and control of biofilm formation. Of 96 isolates, 49% possessed swimming motility, 27% twitching and 52% swarming motility, while 47% were non-motile. Microtitre plate assays for biofilm formation showed a range of biofilm formation ability from biofilm deficient phenotypes to those that formed very thick biofilms. A comparison of the motility and adherence properties of individual strains demonstrated that the presence of swimming and twitching motility positively affected biofilm biomass. Crucially, however, motility was not an absolute requirement for biofilm formation, as 30 non-motile isolates actually formed thick biofilms, and three motile isolates that had both flagella and type IV pili attached only weakly. In addition, CLSM analysis showed that biofilm-forming strains of P. aeruginosa were in fact capable of entrapping non-biofilm forming strains, such that these 'non-biofilm forming' cells could be observed as part of the mature biofilm architecture.ConclusionsClinical isolates that do not produce biofilms in the laboratory must have the ability to survive in the patient lung. We propose that a synergy exists between isolates in vivo, which allows "non biofilm-forming" isolates to be incorporated into the biofilm. Therefore, there is the potential for strains that are apparently non-biofilm forming in vitro to participate in biofilm-mediated pathogenesis in the CF lung.

Increased Biofilm Formation by Nontypeable Haemophilus influenzae Isolates from Patients with Invasive Disease or Otitis Media versus Strains Recovered from Cases of Respiratory Infections

“…This mechanism has been observed in CF-related pulmonary infections, mainly involving Pseudomonas aeruginosa (8)(9)(10). However, recent data have also revealed the presence of NT H. influenzae in biofilm communities in the lower and upper airways, and physical evidence has been shown in experimental models of otitis media (OM) with the detection of biofilm-like structures in the middle-ear mucosa of chinchillas (11,12).…”

Host–microbe interactions as a driver of acclimation to salinity gradients in brown algal cultures

“…However, compared with free-living bacteria in the medium, the genomes of bacteria predominantly attached to algae were enriched notably in membrane transport and secondary metabolism, and impoverished with respect to cell mobility. Although these comparisons were based purely on predictions made from 16S rRNA gene sequences, several of the observations are plausible: flagellar proteins, which were predicted to be less abundant in our algal samples, for example, are usually downregulated during biofilm formation (Guttenplan and Kearns, 2013), and may even be dispensable (Deligianni et al, 2010), while Type VI secretion systems, which were predicted to be more abundant in our algal samples, are transmembrane transporters frequently involved in pathogenesis but also suspected to function in other biotic interactions with hosts (Coulthurst, 2013). Thus, although the predicted overrepresented functional categories need to be interpreted with caution, we nevertheless consider our analysis to provide a good indication for the existence of functional enrichments in our system.…”

A Microfluidic Approach to Investigating a Synergistic Effect of Tobramycin and Sodium Dodecyl Sulfate on Pseudomonas aeruginosa Biofilms

“…The biofilm matrix provides a protective shield to bacterial species that contributes ominously to several clinical and environmental challenges, including antibiotic resistance, symptomatic inflammation, recurrence, and the spread of infectious emboli, reported in previous studies. 7,8 The microbes in biofilm are protected from harsh conditions, such as shear stress, nutrient scarcity, pH fluctuations, oxygen radicals, disinfectants, and antibiotics. Extra polymeric substances engage antimicrobial agents, and minimize the physical stress in microbial communities.…”