Characteristics of invasive Acinetobacter species isolates recovered in a pediatric academic center

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.

In vitro and in vivo Virulence Potential of the Emergent Species of the Acinetobacter baumannii (Ab) Group

“…If so, should we expect worse clinical outcomes upon the acquisition of resistance by these Acinetobacter species? Under this assumption, A. nosocomialis and A. baumannii might have suffered a reduction of intra-species diversity (population bottleneck) resulting from adaptation to the human host and/or antibiotic selection, while the variability observed among isolates of A. pittii , A. seifertii and A. lactucae might reflect their emergence and distinct degrees of adaptation as human nosocomial pathogens (Schleicher et al, 2013; Jain et al, 2016; Chen et al, 2018; Pailhories et al, 2018; Rocha et al, 2018). Nevertheless, it is important to acknowledge that the results provided in our study arise from the usage of in vitro and nematode infection models that do not entirely reflect more complex clinical scenarios and, thus, the extrapolation of these results to infer virulence in the human host must be taken with extreme caution.…”

Genome-Based Epidemiological Analysis of 13 <i>Acinetobacter</i> Strains Isolated from Blood Cultures of Hospitalized Patients from a University Hospital in Japan

“…Another study conducted on 48 Acinetobacter isolates from bacteremia patients demonstrated that A. soli was the most prevalent species in a tertiary hospital setting in Japan (15). Moreover, according to another report (16), the most frequently isolated Acinetobacter species in a pediatric academic center in the U.S. was A. pittii, which accounted for 45.8 of the total number. Importantly, the authors observed significantly higher biofilm formation capabilities by A. pittii than other strains, including A. baumannii, highlighting the importance of being able to discriminate among Acinetobacter species.…”

Accurate Identification of Clinically Important Acinetobacter Spp.: An Update

“…Acinetobacter species were found to be associated with increased mortality [9]. The ACB complex has emerged as a high priority nosocomial pathogen, especially in intensive care units, thereby posing a challenge to infection management practices [10].…”

“…However, identification of Acinetobacter to the species level remains complicated. Clear differentiation among various Acinetobacter species using standard biochemical methods and automated systems are challenging, thus leading to inaccurate identification [9]. Although various molecular methods are available, they are not regularly employed in routine diagnostic laboratories [11].…”

“…Jain et al . reported that A. pittii as the most frequently isolated species with a lower rate of mortality in children [9]. Recent studies from other countries have shown that A. pittii and A. nosocomialis were responsible for 29% of ACB complex bacteremia in the USA, 24–45% in Taiwan, 50% in Korea and 66% in Norway [14].…”