Ecologic Relation between<i>Staphylococcus aureus</i>and Pseudomonas in a Nursery Population

Abstract

The effect of certain nursery procedures on the colonization of newborn infants with Staphylococcus aureus and gram-negative bacilli was examined. During a period of only hexachlorophene handwashing by personnel, 50 per cent of infants were colonized with Staph. aureus at either the nasal or umbilical site. The introduction of hexachlorophene bathing of infants resulted in a decrease in colonization with Staph. aureus to 4 to 6 per cent. The addition of an antibacterial foam to the handwashing procedure resulted in a further small decrease in colonization with Staph. aureus at the nasal site. Concurrent with this decrease was a significant increase in colonization with gram-negative bacilli. A specific inverse relation existed between Staph. aureus and undefined pseudomonas species. This relation can be interpreted as another example of bacterial interference. It is suggested that the spontaneous acquisition of Staph. aureus may prevent the later acquisition of certain gram-negative organisms by newborn infants.