Enterobacter aerogenes outbreak in a neonatal intensive care unit.
BACKGROUND
Enterobacter aerogenes, a Gram-negative bacterium, is an important, although infrequent, cause of nosocomial bacteremia in the hospitalized pediatric and neonatal population. Enterobacter aerogenes was isolated for the first time in our neonatal intensive care unit (NICU) from blood culture of a 5-day-old neonate; 12 more cases were discovered in the next 70 days. The present report summarizes the clinico-bacteriological spectrum and outcome of the affected neonates. Efforts made to find the source of infection and curb the outbreak are also presented.


RESULTS
Thirteen newborns, including seven preterms, acquired E. aerogenes septicemia. Perinatal risk factors were present in all the neonates. The mean birthweight of affected infants was 1880 +/- 540 g. Symptoms appeared at a mean age of 3.5 +/- 1.5 days (range 3-8 days). The clinical presentation was indistinguishable from septicemia caused by other Gram-negative organisms. Complications encountered included sclerema, bleeding diathesis, meningitis and shock. The organism, isolated from blood in all and from the cerebrospinal fluid in two cases, was found to be resistant to all antibiotics in the first five cases, but turned sensitive to gentamicin, cefotaxime and amikacin during the latter half of the epidemic. The bacterium in the last case (no. 13) was again found to be resistant to all the antibiotics. Overall mortality was 46.2%; the mean interval between onset of symptoms and death being 2.3 +/- 1.8 days. The organism was traced to the rubber pipe attached to a foot-operated suction machine in the NICU. The neonatal unit was temporarily closed, fumigated and reopened with strict instructions to follow proper hand washing protocol and ensure cohort nursing of infected infants.


CONCLUSIONS
Enterobacter aerogenes is capable of causing nosocomial outbreaks of septicemia in NICU. Low birthweight infants with associated perinatal risk factors appear to be predisposed. The sensitivity patterns of the isolates highlight the capability of E. aerogenes to acquire or lose resistance to antibiotics rapidly during treatment. A high mortality rate coupled with a short interval between onset of symptoms and death, suggested high virulence of the strain.
Loiwal
V
V
Department of Pediatrics, University College of Medical Sciences, Shahdara, Delhi, India.
Kumar
A
A
Gupta
P
P
Gomber
S
S
Ramachandran
V G
VG
D003428:Cross Infection / Q000188:drug therapy / Q000401:mortality / Q000635:transmission*; D004196:Disease Outbreaks; D004352:Drug Resistance, Microbial; D004754:Enterobacter / Q000302:isolation & purification / Q000472:pathogenicity*; D004756:Enterobacteriaceae Infections / Q000188:drug therapy / Q000401:mortality / Q000635:transmission*; D005260:Female; D006235:Hand Disinfection; D006801:Humans; D007223:Infant; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D017053:Infection Control; D007363:Intensive Care Units, Neonatal; D008297:Male; D012307:Risk Factors; D018805:Sepsis / Q000209:etiology