Following in Real Time the Impact of Pneumococcal Virulence Factors in an Acute Mouse Pneumonia Model Using Bioluminescent Bacteria

Abstract

Pneumonia is one of the major health care problems in developing and industrialized countries and is associated with considerable morbidity and mortality. Despite advances in knowledge of this illness, the availability of intensive care units (ICU), and the use of potent antimicrobial agents and effective vaccines, the mortality rates remain high 1 . Streptococcus pneumoniae is the leading pathogen of community-acquired pneumonia (CAP) and one of the most common causes of bacteremia in humans. This pathogen is equipped with an armamentarium of surface-exposed adhesins and virulence factors contributing to pneumonia and invasive pneumococcal disease (IPD). The assessment of the in vivo role of bacterial fitness or virulence factors is of utmost importance to unravel S. pneumoniae pathogenicity mechanisms. Murine models of pneumonia, bacteremia, and meningitis are being used to determine the impact of pneumococcal factors at different stages of the infection. Here we describe a protocol to monitor in real-time pneumococcal dissemination in mice after intranasal or intraperitoneal infections with bioluminescent bacteria. The results show the multiplication and dissemination of pneumococci in the lower respiratory tract and blood, which can be visualized and evaluated using an imaging system and the accompanying analysis software. Video LinkThe video component of this article can be found at

Structure of the pneumococcal l,d‐carboxypeptidase DacB and pathophysiological effects of disabled cell wall hydrolases DacA and DacB

“…The in vivo mouse infection experiments and bioimaging as well as the in vitro , cell culture‐based phagocytosis and adherence assays were carried out identical to the recently described protocols (Jensch et al ., ; Hartel et al ., ; Saleh et al ., 2013; 2014). The experimental details of each method and the procedure of data evaluation are provided in the Supporting Information.…”

Pneumococcal lipoproteins involved in bacterial fitness, virulence, and immune evasion

“…In contrast, deletion of metQ in S. pneumoniae serotype 2 strain D39 significantly attenuated virulence in a mouse model of acute pneumonia as monitored real time with bioluminescent imaging (Table ; Fig. ) . Moreover, vaccination with recombinant MetQ failed in a first attempt to prevent systemic pneumococcal infection after heterologous challenge .…”

Selective substrate uptake: The role of ATP-binding cassette (ABC) importers in pathogenesis

“…However, for single-strain infections, virulence of the metQ mutant in CD1 mice was unchanged compared to wildtype in the S. pneumoniae serotype 3 strain [91]. In contrast, bioluminescent imaging in real-time showed a metQ mutation in S. pneumoniae serotype 2 strain D39 showed significantly attenuated virulence in an acute pneumonia mouse model [92]. Similarly, metQ of the methionine MetNIQ transporter plays no role in epithelial cell invasion of M. catarrhalis , but facilitates persistence in the murine lungs [85].…”