Dg. De Viedma et al., Evidence of nosocomial Stenothrophomonas maltophilia cross-infection in a neonatology unit analyzed by three molecular typing methods, INFECT CONT, 20(12), 1999, pp. 816-820
OBJECTIVE: To characterize the epidemiological relationships among Stenotro
phomonas maltophilia isolates in the neonatology unit of our institution ov
er a 4-month period in which an increased number of isolates was observed.
SETTING: The neonatology ward in a 2,000-bed university hospital in Madrid,
Spain.
DESIGN: A retrospective molecular epidemiological analysis using three diff
erent typing methods, arbitrarily primed polymerase chain reaction (PCR), p
ulsed-field gel electrophoresis, and enterobacterial repetitive intergenic
consensus-PCR, was performed with 11 isolates obtained from seven neonates
over a 4-month period. Presumed unrelated isolates also were included as co
ntrols. A similarity dendrogram was obtained, to analyze the genetic relate
dness among the isolates.
RESULTS: All isolates from the neonates, except one, showed a remarkably hi
gh homology among their typing patterns for the three methods assayed and c
lustered in the relatedness dendrogram at 96% similarity. The unrelated str
ains selected as controls were unclustered. The index case was considered t
o be a newborn who had an S maltophilia isolate from a culture drawn on the
day of admission to the neonatology unit and which was included in the clu
stered similarity group.
CONCLUSIONS: Such a high genetic similarity among the isolates, together wi
th the presence of an index case who had been colonized or infected by S ma
ltophilia before arrival at our institution, constitutes the first evidence
of nosocomial cross-transmission of this microorganism (Infect Control Hos
p Epidemiol 1999;20:816-820).