Acinetobacter ursingii: An Unusual Infectious Agent of Early-onset Neonatal Sepsis

To the Editors: Acinetobacter spp. are nonmotile, aerobic, nonfermentative Gram-negative coccobacilli which are widespread in natural and hospital environments.1 Some species such as Acinetobacter ursingii are rarely isolated as human pathogens. Several cases of late-onset sepsis in neonatal intensive care units have been reported. Here, we present a case of early-onset sepsis and pneumonia by A. ursingii in a full-term newborn. A male baby born from normal vaginal delivery at 40 weeks of gestation, weighing 3460 g, with Apgar score of 9 and 10 at 1 and 5 minutes, was referred to the neonate intensive care unit 4 hours after birth. Maternal Streptococcus agalactiae test was negative, time of rupture of membranes was 5 hours without signs of chorioamnionitis. The clinical findings showed tachypnea, grunting and intercostal retractions. Laboratory tests showed elevated interleukin-6 values (8630 pg/mL). Leukocyte (8360/µL) and neutrophil (5270/µL) counts and C-reactive protein (1.1 mg/L) were normal. Chest X-ray showed bilateral infiltrates. Cerebrospinal fluid analysis was normal. Treatment with intravenous ampicillin and gentamycin was started. The microbiology service reported a positive result of the blood culture to A. ursingii. The baby recovered uneventfully after an 8-day course of antibiotics. Follow-up blood cultures were negative. After the description of A. ursingii by Nemec et al,1 some publications have dealt with this bacterium as an important opportunistic pathogen. Although some cases of A. ursingii bacteremia have been described in older children, most pediatric reports describe infection in the setting of neonatal intensive care units, including nosocomial outbreaks. Eleven cases of neonatal A. ursingii infection have been described in detail to date.2–5 These include 5 cases initially reported by Kilic et al2 as a new species, Acinetobacter septicus, although further analysis by Nemec et al1 suggested, on the basis of 16Sr DNA similarities and phenotypical characteristics, that the strain isolated was A. ursingii and did not represent a novel species.1 Median gestational age and birthweight of the cases previously reported were 32 weeks and 1100 g, respectively. All the 9 babies in whom the mode of delivery was reported were born by cesarean section. All had predisposing underlying pathologies and were already admitted to the neonatal intensive care unit by the time symptoms developed. Survival rates were relatively high (8 of 11), including 2 babies with persistent bacteremia. In general, A. ursingii is susceptible to most clinically relevant drugs, but carbapenemase-producing strains have been reported in the Netherlands, Japan and Argentina. To the best of our knowledge, this is the first report of early-onset neonatal sepsis caused by A. ursingii in a baby with no known risk factors for infection. An outbreak of bacteremia by A. ursingii was reported in 2 immunocompetent pregnant women in Japan, but their infants did not show signs of infection; unfortunately, the placenta was not available for microbiologic study in our case, but there were no signs of maternal infection. In conclusion, A. ursingii is a rare cause of nosocomial infection in high-risk newborns, but it can also cause early-onset sepsis in infants with no known risk factors.