Lactobacillus rhamnosus GG inhibits invasion of cultured human respiratory cells by prtF1-positive macrolide-resistant group A streptococci.
OBJECTIVE
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.


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.


CONCLUSIONS
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.
Princivalli
M S
MS
Institute of Microbiology and Biomedical Sciences, Polytechnic University of Marche, Medical School, Ancona, Italy.
Paoletti
C
C
Magi
G
G
Palmieri
C
C
Ferrante
L
L
Facinelli
B
B
D018829:Adhesins, Bacterial / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000898:Antibiosis; D002460:Cell Line; D002648:Child; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology; D006801:Humans; D052201:Lacticaseibacillus rhamnosus / Q000254:growth & development*; D018942:Macrolides / Q000494:pharmacology; D019936:Probiotics; D012137:Respiratory System / Q000166:cytology / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*
D018829:Adhesins, Bacterial; D000900:Anti-Bacterial Agents; D018942:Macrolides; C078635:fibronectin-binding proteins, bacterial; D004917:Erythromycin