Abstract
Coagulase negative staphylococci and micrococci seem to be increasing in importance as pathogens, especially as opportunistic invaders of internal artificial prostheses and surgical wounds. They are also of significance in the etiology of urinary tract infections and of low grade but troublesome bacteremias. Thus reliance on a positive coagulase test alone as an indicator of potential pathogenicity amongst the Micrococcaceae is open to some criticism. As it is now possible to divide staphylococci and micrococci into a number of clearly defined subgroups, it was considered of interest to learn more about the occurrence of these groups in man. A study was made of the distribution of the Baird Parker subgroups of aerobic, Gram positive, catalase positive cocci on the skin and mucous membrane of infants under normal nursery conditions and under the conditions in a premature intensive care unit. Most of the colonies obtained belonged to Baird Parker's subgroup staphylococcus II (S.II). Micrococci were seldom isolated. There appeared to be no difference in occurrence of the various subgroups between premature infants, normal infants and staff, nor between male and female infants. Coagulase positive strains of staphylococci (S.I.) were recovered from 16.4% of the infants, the highest incidence (8.1%) being in the nasal cavity. As S.II cocci have been shown to possess a high lipase activity, it may be that the increased activity of sebaceous glands at birth together with the presence of the oily vernix caseosa provide a favorable environment for this subgroup. Of the various coagulase negative staphylococci and micrococci, S.II types are most commonly associated with abnormal conditions. The extent of their virulence is difficult to gauge although it would be deemed to be low if reliance were placed on the production of the enzymes coagulase, lysozyme and deoxyribonuclease. However despite the fact that they produce very little somatic response, the possible association of S.II strains and other subgroups of coagulase negative cocci with disease in the newborn, especially in jaundiced babies and in infants with nonspecific symptoms who fail to thrive, should not be underestimated.