Outbreak of septicaemia in neonates caused by Acinetobacter junii investigated by amplified ribosomal DNA restriction analysis (ARDRA) and four typing methods

Septicaemia caused by Acinetobacter occurred in six infants in the neonatal unit. A total of 18 acinetobacters were isolated from blood cultures, cultures of intravascular catheters, and surveillance cultures. Twelve isolates from the six affected infants were identified as Acinetobacter junii by the use of a novel method, amplified ribosomal DNA restriction analysis (ARDRA). Typing of the organisms using the biochemical profiles of the API 20NE system, antibiogram typing, cell envelope protein electrophoresis, and PCR fingerprinting with two primer sets, ERIC1/ERIC2 and ERIC2/1026, showed that these 12 isolates were indistinguishable, whereas the remaining six isolates were different. The six infants recovered after therapy with ciprofloxacin alone in five cases and with a combination of ciprofloxacin and gentamicin in one case. This study showed that A. junii is capable of causing a serious, though non-fatal infection in neonates. The combined use of genotypic and phenotypic methods allowed the rapid separation of epidemic from non-epidemic isolates. It is concluded that for a better understanding of the role of the various Acinetobacter genomic species in human pathology, identification of acinetobacters according to the recent taxonomy is imperative.