In vitro biofilm formation by Streptococcus pneumoniae as a predictor of post‐vaccination emerging serotypes colonizing the human nasopharynx

Abstract

The increasing use of the 7-valent pneumococcal conjugate vaccine has been accompanied by the rise of non-vaccine serotypes colonizing the human nasopharynx. The vast majority of infections are caused by microorganisms that grow in biofilms. It has recently been shown that the formation of Streptococcus pneumoniae biofilms in vivo and in vitro is hindered by the presence of capsular polysaccharide. The biofilm-forming capacity of pneumococcal clinical isolates with different types of capsular polysaccharide and various isogenic transformants was examined. Strains of serotypes 19A and 19F, but not 19B and 19C, formed ≥ 80% of the quantity of biofilm associated with a non-encapsulated control strain. Strains of serogroup 6 also showed significant biofilm-forming capacity. The capsules of serotypes 19A and 19F, and serogroup 6 contain the disaccharides α-D-Glcp-(1→2)-α-L-Rhap-(1→ and α-D-Glcp-(1→3)-α-L-Rhap-(1→. Serotype 18A and serotypes 18B/18C have very similar capsular disaccharides: α-D-GlcpNAc-(1→3)-β-L-Rhap-(1→ and α-D-Glcp-(1→3)-β-L-Rhap-(1→ respectively. However, the strains of serogroup 18 showed impaired biofilm formation. These results indicate that the chemical composition/structure of the capsular polysaccharide is crucial to the biofilm-forming capacity of pneumococcal serotypes. Testing of the in vitro biofilm-forming ability of isogenic transformants expressing different capsular polysaccharides may help predict the emergence of colonizing, non-vaccine serotypes.

N -Acetyl- l -Cysteine and Cysteamine as New Strategies against Mixed Biofilms of Nonencapsulated Streptococcus pneumoniae and Nontypeable Haemophilus influenzae

“…Using an NE S. pneumoniae strain that produces fairly large amounts of biofilm in vitro (15)(16)(17)(18) and a modified culture medium, the present work examined the influence of initial cell concentrations on pneumococcal and NT H. influenzae survival (Fig. 1).…”

“…The main biopolymer components of the extracellular matrix are extracellular polysaccharide(s) and other macromolecules such as proteins and nucleic acids. NE S. pneumoniae has a marked capacity to form biofilms in vitro since the CPS usually behaves as an obstacle to biofilm formation (15)(16)(17)(18). NT H. influenzae isolated from patients with AOM, cystic fibrosis (CF), or chronic obstructive pulmonary disease (COPD) has been proposed to form biofilms in vitro and in vivo (19)(20)(21), although a biofilm-specific extracellular polysaccharide has never been described.…”

Widening the antimicrobial spectrum of esters of bicyclic amines: In vitro effect on gram-positive Streptococcus pneumoniae and gram-negative non-typeable Haemophilus influenzae biofilms

“…Bacterial strains were grown at 37C in C+Y medium. Biofilm formation on 96-well polystyrene microtiter plates (Costar 3595; Corning) was obtained as previously described [19,20]. Briefly, cells were grown in C+Y medium to an OD550 of 0.…”

Autolysin-Independent DNA Release inStreptococcus pneumoniae in vitroBiofilms

“…Biofilm formation was determined by the ability of cells to adhere to the walls and base of 96-well (flat-bottomed) polystyrene microtiter dishes (Costar 3595; Corning Incorporated), using a modification of a previously reported protocol (67). Unless stated otherwise, cells grown in C+Y medium to an A 550 of ≈ 0.5-0.…”

“…Plates were incubated at 34°C for 3, 4.5 and 5 h and bacterial growth determined by measuring the A 595 using a VersaMax microplate absorbance reader (Molecular Devices). The biofilm formed was stained with 1% crystal violet (67).…”