Abstract
BackgroundAcinetobacter species are associated with increasing mortality due to emerging drug-resistance. Pediatric Acinetobacter infections are largely undefined in developed countries and clinical laboratory identification methods do not reliably differentiate between members of the Acinetobacter calcoaceticus-baumannii complex, leading to improper identification. Therefore we aimed to determine risk factors for invasive Acinetobacter infections within an academic, pediatric setting as well as defining microbiologic characteristics of predominant strains.MethodsTwenty-four invasive Acinetobacter isolates were collected from 2009–2013. Comparative sequence analysis of the rpoB gene was performed coupled with phenotypic characterization of antibiotic resistance, motility, biofilm production and clinical correlation.ResultsAffected patients had a median age of 3.5 years, and 71 % had a central catheter infection source. rpoB gene sequencing revealed a predominance of A. pittii (45.8 %) and A. baumannii (33.3 %) strains. There was increasing incidence of A. pittii over the study. Two fatalities occurred in the A. pittii group. Seventeen percent of isolates were multi-drug resistant. A pittii and A. baumannii strains were similar in motility, but A pittii strains had significantly more biofilm production (P value = 0.018).ConclusionsA. pittii was the most isolated species highlighting the need for proper species identification. The isolated strains had limited acute mortality in children, but the occurrence of more multi-drug resistant strains in the future is a distinct possibility, justifying continued research and accurate species identification.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1678-9) contains supplementary material, which is available to authorized users.
Highlights
Acinetobacter species are associated with increasing mortality due to emerging drug-resistance
Inclusion criteria included pediatric patients less than 21 years old with at least one positive blood, bone, endotracheal, peritoneal, or cerebrospinal fluid culture result positive for Acinetobacter species [all identified as A. baumannii or A. baumannii complex by the clinical laboratory using Vitek 2 and other phenotypic methods as needed]
A phylogenetic tree was derived after comparative sequence analysis of hyper-variable regions of the rpoB gene from Acinetobacter isolates using the BioNJ algorithm [21] (Fig. 1)
Summary
Acinetobacter species are associated with increasing mortality due to emerging drug-resistance. We aimed to determine risk factors for invasive Acinetobacter infections within an academic, pediatric setting as well as defining microbiologic characteristics of predominant strains. Invasive Acinetobacter infections associated with large pediatric, academic institutes in developed countries are still poorly defined due to unclear risk factors. Recent studies documented risk factors for invasive infections as catheter insertions, prolonged use of antibiotics, as well as underlying chronic diseases [5, 12]. It is not clear if these risk factors are universal in all hospital settings, including locations outside of intensive care units. Improvements in bacterial sequencing, in particular the Acinetobacter rpoB gene, have allowed us to more accurately identify clinically important Acinetobacter species [13,14,15]
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