OBJECTIVE: The objective of the study was to investigate the application on growth of anginosus
group of Streptococci (AGS) by Ps. aeruginosa when grown together, and the effect on the
virulence of Ps. aeruginosa when grown together with AGS on a biofilm model.
METHODOLOGY: In this study we used nitrocellulose filter paper as biofilm model representing
the lung epithelium. The AGS strains used were AGS F (S. constellatus from bronchiectasis),
AGS 3a (S. anginosus from cystic fibrosis exacerbation), AGS PC 4890 (S. anginosus from dental
plaque), AGS 2227 (S. Intermedius from unknown source), AGS EF 52 (S. contellatus from
supra gingival plaque), AGS AC 9612 (S. anginosus from supra gingival dental plaque), AGS AM
699 (S. constellatus from supra gingival dental plaque) and AGS 1a (S. anginosus from cystic
fibrosis exacerbation). Ps. aeruginosa strain used was LES 1 (Liverpoolepidemic strain of Ps.
RESULTS: A concentration of AGS strain in monoculture (1x10
cfu), Ps. aeruginosa monoculture
cfu), AGS+Ps. aeruginosa mixed culture (1x10
cfu of each) was used to inoculate the
biofilm. NAS agar plate and PIA agar plates were used to count the growth of AGS and Ps.
Aeruginosarespectively, and pyocyanin and elastase assays were done to check the virulence
of the Ps. aeruginosa. It was observed that there was a 10 folds increase in the growth of all the
AGS strains; when grown in co-culture with the Ps. aeruginosa strain as compared to when
grown in mono culture; both in the 24 and 48 hours aerobically incubated biofilms. When grown
in an anaerobic environment AGS in monoculture had the same growth as when grown aerobically
with Ps. aeruginosain co culture. There was no effect in the growth of Ps. aeruginosa in
mono or co culture with AGS in 24 and 48 hours biofilm.
CONCLUSION: The data supported the hypothesis that anginosus group of Streptococci grows
better in presence of Ps. Aeruginosain a co-culture, as compared to when grown alone in an
anaerobic environment, whereas the virulence factors ( Pyocyanin and Elsastase production) of
Ps. aeruginosa increases when grown in co-culture as compared to when grown alone in aerobic
Anginosus group of Streptococci (AGS), Cystic fibrosis, Commensals,Biofilm content.