The isolation of streptococci from human faeces

Area of Science:

• Microbiology
• Gastrointestinal Health
• Bacteriology

Background:

• Streptococci are common bacteria found in the human gut.
• Accurate isolation and identification of fecal streptococci are crucial for understanding gut microbiota composition and its health implications.

Purpose of the Study:

• To develop and evaluate three selective media for the efficient isolation of streptococci from human fecal samples.
• To identify the diversity and prevalence of streptococcal taxa in the feces of healthy adults.

Main Methods:

• Fecal samples from twelve healthy adults were collected and serially diluted.
• Diluted samples were plated on three newly designed selective media and incubated.
• Colonies were counted, subcultured, and identified to the species or group level.

Main Results:

• A total of 13 distinct streptococcal taxa were identified across all samples.
• Streptococcus faecium, Streptococcus mutans, Streptococcus milleri, Streptococcus faecalis, and Streptococcus mitior were frequently detected (in over 50% of samples).
• Individual samples harbored 2-7 streptococcal taxa, with a mean of 4.6, and viable counts ranged from 3 x 10(3) to 3 x 10(8) per gram.

Conclusions:

• The developed selective media are effective for isolating a wide range of streptococcal species from human feces.
• The study provides valuable data on the composition of the fecal streptococcal microbiota in healthy adults.
• The findings highlight the complexity of the gut streptococcal population and warrant further investigation into their ecological significance.