Serratia: a problem in a neonatal nursery

We have noted an increased incidence of Serratia species isolates in our Special Care Nursery recently and have reviewed our experience over the 7 year period from 1976 to 1982. Fifty newborn infants had strains of Serratia isolated, 30 of which were found in 1982. Two strains of Serratia species were isolated: Serratia marcescens in 46 newborn infants and Serratia liquefaciens in six, with both types being found in two infants. All isolates were sensitive initially to gentamicin, kanamycin sulphate, chloramphenicol and co-trimoxazole. However, resistance was documented subsequently to each of these antibiotics. Only 64% of isolates only were sensitive initially to ampicillin; 27% subsequently developed resistance Recent isolates were sensitive to cefotaxime sodium.
Twenty-nine infants (58%) were colonized, and 1.6 (32%) had minor infections such as conjunctivitis. However in five infants (10%) life threatening illness occurred. Of the five infants with serious infection two had meningitis and three were septicaemtc; one infant died. In both infants with meningitis difficulty was experienced in eradicating the organism and porencephaly developed in both.