Emerging, Non-PCV13 Serotypes 11A and 35B of Streptococcus pneumoniae Show High Potential for Biofilm Formation In Vitro

Abstract

BackgroundSince the use of pneumococcal conjugate vaccines PCV7 and PCV13 in children became widespread, invasive pneumococcal disease (IPD) has dramatically decreased. Nevertheless, there has been a rise in incidence of Streptococcus pneumoniae non-vaccine serotypes (NVT) colonising the human nasopharynx. Nasopharyngeal colonisation, an essential step in the development of S. pneumoniae-induced IPD, is associated with biofilm formation. Although the capsule is the main pneumococcal virulence factor, the formation of pneumococcal biofilms might, in fact, be limited by the presence of capsular polysaccharide (CPS).Methodology/Principal FindingsWe used clinical isolates of 16 emerging, non-PCV13 serotypes as well as isogenic transformants of the same serotypes. The biofilm formation capacity of isogenic transformants expressing CPSs from NVT was evaluated in vitro to ascertain whether this trait can be used to predict the emergence of NVT. Fourteen out of 16 NVT analysed were not good biofilm formers, presumably because of the presence of CPS. In contrast, serotypes 11A and 35B formed ≥45% of the biofilm produced by the non-encapsulated M11 strain.Conclusions/SignificanceThis study suggest that emerging, NVT serotypes 11A and 35B deserve a close surveillance.

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).…”

“…S. pneumoniae and NT H. influenzae are nasopharyngeal commensals associated with many common respiratory tract infections. Several known virulence factors produced by these pathogens have been associated with their ability to form biofilms, e.g., the CPS, several surface proteins, the neuraminidases NanA and NanB, and various quorum-sensing systems (15,16,18,29,30). Interestingly, recent experimental evidence has shown that some NE S. pneumoniae strains lack several common surface proteins expressed by encapsulated pneumococci (e.g., the cholinebinding proteins PspA, PspC, and PcpA) but express a specific virulence factor, PspK (an LPxTG binding protein), which has been shown to increase NE S. pneumoniae colonization and virulence during AOM (for a review, see reference 11).…”

“…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.…”

Epidemiological and molecular characterization of Streptococcus pneumoniae carriage strains in pre-school children in Arkhangelsk, northern European Russia, prior to the introduction of conjugate pneumococcal vaccines

“…The epidemiology of pneumococcal disease prior to the introduction of pneumococcal vaccines was dominated by the spread of global disease-causing epidemic clones, both multidrug-resistant (MDR) and antimicrobial susceptible clones [6]. The success of epidemic clones, though not well understood, has been linked to certain capsular types [7,8], carriage of a pilus islet [9] and various virulence factors [10]. Mass vaccination has reduced the occurrence of MDR Pneumococcal Molecular Epidemiology Network (PMEN) clones with serotypes covered by the vaccine.…”

Emergence of Multidrug-Resistant Pneumococcal Serotype 35B among Children in the United States

“…Possibly, the high rates of comorbidity (Ͼ50%) among patients with an invasive serotype 35B isolate in our study reflect the pathogenic potential of a normally low-pathogenic strain within susceptible populations. In vitro studies show that serotype 35B is capable of forming substantial amounts of biofilm, similar to 19F and 19A, which may facilitate nasopharyngeal colonization and mucosal disease (35). Pneumococcal virulence factors such as pili have been found among CC558 and CC156 isolates (25,36,37).…”