Lactobacillus rhamnosus GG inhibits invasion of cultured human respiratory cells by prtF1-positive macrolide-resistant group A streptococci
Article first published online: 23 JAN 2009
© 2009 The Authors. Journal compilation © 2009 The Society for Applied Microbiology
Letters in Applied Microbiology
Volume 48, Issue 3, pages 368–372, March 2009
How to Cite
Princivalli, M.S., Paoletti, C., Magi, G., Palmieri, C., Ferrante, L. and Facinelli, B. (2009), Lactobacillus rhamnosus GG inhibits invasion of cultured human respiratory cells by prtF1-positive macrolide-resistant group A streptococci. Letters in Applied Microbiology, 48: 368–372. doi: 10.1111/j.1472-765X.2008.02540.x
- Issue published online: 9 FEB 2009
- Article first published online: 23 JAN 2009
- 2008/1336: received 31 July 2008, revised 20 October 2008 and accepted 3 November 2008
- A549 cells;
- cell invasion;
- group A streptococci;
- Lactobacillus rhamnosus GG
Aims: This study was designed to determine whether the probiotic strain Lactobacillus GG, which is extensively used in the treatment and prevention of intestinal disorders, is able to inhibit invasion of cultured human respiratory cells by macrolide-resistant group A streptococci (GAS) carrying the prtF1 gene, which encodes the fibronectin (Fn)-binding invasin F1.
Methods and Results: Eight prtF1-positive erythromycin-resistant GAS strains were used to infect A549 monolayers in competition and displacement assays with Lactobacillus GG. Live (L-LGG) and heat-killed (HK-LGG) lactobacilli and their spent culture supernatant (SCS) significantly reduced (P < 0·001) GAS invasion efficiency in both assays. No antibacterial activity of Lactobacillus GG against GAS was detected. Both L-LGG and HK-LGG and all prtF1-positive GAS induced a strong agglutination reaction using Fn-coated particles.
Conclusions: Lactobacillus GG exerts an antagonistic action against GAS by inhibiting cell invasion. Competitive binding of Lactobacillus GG and GAS to Fn might be involved in the inhibition process.
Significance and Impact of the Study: The finding that Lactobacillus GG can prevent in vitro invasion of respiratory cells by GAS suggests new applications for this probiotic strain and warrants further studies of its capacity to prevent GAS throat infections.