The Natural History of Bacterial Colonization of the Newborn in a Maternity Hospital (Part I)

Abstract

Bacteriological examinations were performed on 1103 infants to determine the ages at which the newborn are colonized at different sites by bacteria, and with which organisms. On the day of birth, specimens for culture included aspirated gastric contents, and swabs from nose, throat, groin and rectum; on Day 3 the umbilical cord clamp with a section of the cord, swabs from nose, throat, groin and rectum; on days 5 and 1, and weekly thereafter, swabs from the same 4 sites. These examinations included identification of the individual bacterial species. The mass of information so obtained was analysed by computer. The high level of bacterial colonization by day 3 was striking and, indeed, large numbers of potential pathogens were grown from infants within one hour of birth. Staphylococcus aureus was found only in very small numbers of infants, e.g. only 2.6 per cent of infants' umbilical cords on day 3, and 4 per cent of infants' noses on day 7. If the levels of colonization reflect the risks of infection, Pseudomonas aeruginosa ranks close to Staph. aureus in the newborn nursery of the modern maternity hospital. Forty two different species of bacteria were isolated from these infants of which 24 were potential pathogens and of the latter, gram-negative organisms greatly outnumbered the gram-positive. This high incidence of gram-negative colonization in a large series of hospitalized neonates may be a normal phenomenon but it suggests that the risk of infection is today greater with gram-negative than with gram-positive bacteria. The figures for carriage of pathogenic staphylococci in the present investigation contrast markedly with the figures reported by many workers between 1950 and 1960.