title: Prevalence of gram-negative rods in the normal pharyngeal flora.
abstract: We obtained throat cultures from 100 randomly selected people free from any chronic upper or lower respiratory disease who did not work in a hospital and who had not experienced any acute illness or received any antibacterial therapy in the 4 weeks preceding culture. Eighteen percent harbored either a species of Enterobacteriaceae or Pseudomonas aeruginosa in their pharynx. In all cases, colony counts were low, the majority being detected in broth media selective for Gram-negative rods. There were no clear-cut age or sex distributions of Gram-negative pharyngeal carriage. These data imply that, in at least some cases, isolation of Gram-negative rods from sputum of untreated patients may be a normal finding, and that in some patients with pulmonary infection, the pretreatment, upper respiratory tract flora may serve as the source of subsequent superinfection with Gram-negative rods.
mesh_terms: D000150:Acinetobacter / Q000302:isolation & purification; D000293:Adolescent; D000328:Adult; D000368:Aged; D001419:Bacteria / Q000302:isolation & purification*; D002648:Child; D002675:Child, Preschool; D004755:Enterobacteriaceae / Q000302:isolation & purification*; D004926:Escherichia coli / Q000302:isolation & purification; D005260:Female; D006801:Humans; D007711:Klebsiella pneumoniae / Q000302:isolation & purification; D008297:Male; D008875:Middle Aged; D009016:Moraxella / Q000302:isolation & purification; D010614:Pharynx / Q000382:microbiology*; D011513:Proteus mirabilis / Q000302:isolation & purification; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D013183:Sputum / Q000382:microbiology