Quantitative Analyses of the Normal Throat Flora of Children with Upper Respiratory Tract Infections

: Relationship between the normal throat flora and pathogenic bacteria recovered from the throat in 139 children with upper respiratory tract infections in winter were studied using quantitative analyses. Pathogenic bacteria examined include S. pyogenes, H. influenzae, S. aureus, and S. pneumoniae, and the normal floras include alpha-streptococci, gamma-streptococci, Neisseria species, and Micrococci. Children with S. pyogenes in their throats (S. pyogenes group) were examined with anti-streptococcal antibodies such as anti-streptolysin O, anti-streptokinase, and anti-deoxyribonuclease B. Eighty seven pathogenic bacteria were recovered from 72 children (51.8%) out of 139. S. pyogenes and S. pneumoniae groups showed significantly lower alpha-streptococci and gamma-streptococci in incidence of appearance when compared with children with the no pathogenic bacteria in their throats (no bacteria group). H. influenzae group showed significantly lower gamma-streptococci and higher Neisseria sp. in incidence of appearance compared with the no bacteria group. Positive cases for anti-streptococcal antibodies showed a significantly lower alpha-streptococci in number compared with negative cases for antibodies and the no bacteria group, and a significantly lower gamma-streptococci in incidence of appearance compared with the no bacteria group. These data suggest that the normal throat flora may have a role in prevention of colonization by the pathogenic bacteria in vivo, as were shown in vitro by many authors, and that the quantitative analysis of the normal flora is useful because this methodology might reveal whether the bacteria recovered from the throat show the pathogenicity.