A comparison of strains of Serratia marcescens isolated from neonates with strains isolated from sporadic and epidemic infections in adults.

As a result of the increased number of outbreaks of Serratia marcescens in special care baby units in the UK, a study was undertaken to compare strains isolated from outbreaks of neonatal infection with strains isolated from outbreaks of infections in adults and with isolates from sporadic infections. None of the biochemical, serological, bacteriological markers examined could distinguish the three groups of strains. When considered as groups there was no difference in the ability of the strains to survive desiccation on hands. Strains from neonatal and sporadic infections were more sensitive to antibiotics than adult epidemic strains. The feature common to all of the neonatal strains tested was the ability to agglutinate one or more species of erythrocytes in the presence of mannose. Only one strain in each of the other two groups possessed mannose resistant haemagglutinins.