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Loss of the group A Streptococcus regulator Srv decreases biofilm formation in vivo in an otitis media model of infection.
- Source :
-
Infection and immunity [Infect Immun] 2010 Nov; Vol. 78 (11), pp. 4800-8. Date of Electronic Publication: 2010 Aug 30. - Publication Year :
- 2010
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Abstract
- Group A Streptococcus (GAS) is a common causative agent of pharyngitis, but the role of GAS in otitis media is underappreciated. In this study, we sought to test the hypothesis that GAS colonizes the middle ear and establishes itself in localized, three-dimensional communities representative of biofilms. To test this hypothesis, the middle ears of chinchillas were infected with either a strain of GAS capable of forming biofilms in vitro (MGAS5005) or a strain deficient in biofilm formation due to the lack of the transcriptional regulator Srv (MGAS5005 Δsrv). Infection resulted in the formation of large, macroscopic structures within the middle ears of MGAS5005- and MGAS5005 Δsrv-infected animals. Plate counts, scanning electron microscopy, LIVE/DEAD staining, and Gram staining revealed a difference in the distributions of MGAS5005 versus MGAS5005 Δsrv in the infected samples. High numbers of CFU of MGAS5005 Δsrv were isolated from the middle ear effusion, and MGAS5005 Δsrv was found randomly distributed throughout the excised macroscopic structure. In contrast, MGAS5005 was found in densely packed microcolonies indicative of biofilms within the excised material from the middle ear. CFU levels of MGAS5005 from the effusion were significantly lower than that of MGAS5005 Δsrv early during the course of infection. Allelic replacement of the chromosomally encoded streptococcal cysteine protease (speB) in the MGAS5005 Δsrv background restored biofilm formation in vivo. Interestingly, our results suggest that GAS naturally forms a biofilm during otitis media but that biofilm formation is not required to establish infection following transbullar inoculation of chinchillas.
- Subjects :
- Animals
Bacterial Proteins genetics
Chinchilla
Ear, Middle microbiology
Exotoxins genetics
Exotoxins metabolism
Humans
Microscopy, Electron, Scanning
Streptococcal Infections microbiology
Streptococcus pyogenes genetics
Streptococcus pyogenes growth & development
Streptococcus pyogenes metabolism
Bacterial Proteins metabolism
Biofilms growth & development
Disease Models, Animal
Gene Expression Regulation, Bacterial
Otitis Media with Effusion microbiology
Streptococcus pyogenes pathogenicity
Subjects
Details
- Language :
- English
- ISSN :
- 1098-5522
- Volume :
- 78
- Issue :
- 11
- Database :
- MEDLINE
- Journal :
- Infection and immunity
- Publication Type :
- Academic Journal
- Accession number :
- 20805338
- Full Text :
- https://doi.org/10.1128/IAI.00255-10