Serratia marcescens, a gram-negative facultative
bacillus, is an important cause of nosocomial
infections (N.I.). The infection commonly involves
the respiratory tract, blood stream, urinary tract and
skin. Severe infections by the organism have been reported
in small children especially in neonatal intensive
care unit (N.I.C.U.), in immunocompromised
patients and in patients who received prolonged
courses of antimicrobial treatment. However, most
studies failed to identify the reservoirs of S. marcescens
and the correlation between the strains isolated from
patients and from their environments. Epidemiological
study of S. marcescens could be performed by plasmid
analysis, ribotyping, polymerase chain reaction
(PCR). Total DNA analysis by pulsed field gel
electrophoresis (P.F.G.E.) has been shown to be the
best technique in outbreak studies