Changes in aerobic pharyngeal flora related to antibiotic use and the emergence of gram-negative bacilli.
Pharyngeal flora were evaluated semi-quantitatively by counting and differentiating the colonies growing on blood agar plates into four major bacterial groups. In children they consisted mainly of alpha-streptococci, followed by smaller portions of Neisseria, and of gram-positive organisms other than alpha-streptococci. Gram-negative bacilli did not occur under normal conditions. Oral ampicillin in a daily dose of 50 mg/kg caused suppression of the alpha-streptococci, and promoted emergence of gram-negative bacilli. Oral cephalexin in the same dose caused changes in the same direction, but less extensively than ampicillin . Parenteral aminoglycoside antibiotics in usual dosage did not change the pharyngeal flora. Differential counting of the growth is a simple and useful tool to evaluate the ecology of pharyngeal flora. It serves to monitor overgrowth of resistant organisms in the respiratory tract.
D000284:Administration, Oral; D000332:Aerobiosis; D000617:Aminoglycosides / Q000494:pharmacology; D000667:Ampicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D006328:Cardiac Catheterization; D002506:Cephalexin / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D002986:Clinical Trials as Topic; D006801:Humans; D007223:Infant; D007273:Injections, Intramuscular; D009343:Neisseria / Q000187:drug effects; D010614:Pharynx / Q000382:microbiology*; D013297:Streptococcus pyogenes / Q000187:drug effects
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000667:Ampicillin; D002506:Cephalexin