Fatal pulmonary infection associated with a novel organism, "para-streptomyces abscessus"

Abstract

Actinomycetes are increasingly recognized as pathogenic in the immunocompromised host. We isolated an asporogenous, nonmotile, aerobic gram-positive rod from a transplant recipient with a fatal pulmonary infection. The pathology was similar to that associated with Rhodococcus equi, including intra-histiocytic localization. The organism was relatively inert in standard biochemical tests. 16S rRNA gene sequencing indicated a potentially unique organism most closely related to the genus Streptomyces, for which we propose the name "Para-streptomyces abscessus."

FIG. 1.

Gram stain of Parastreptomyces abscessus from blood culture medium, showing pleomorphic, slightly branching, gram-positive rods.

FIG. 2.

Lung biopsy tissue imprints of Parastreptomyces abscessus infection, showing predominantly coccoid gram-variable forms.

FIG. 3.

Neighbor-joining dendrogram based on 1,256 consecutive positions of the 16S rRNA gene with 1,000 bootstrap replications, showing the phylogenetic relationships of Parastreptomyces abscessus to species phenotypically related to the members of the order Actinomycetales. Numbers at each node correspond to the bootstrap values. GenBank accession numbers and strain numbers where appropriate are included.