Genotyping of Nocardia farcinica with multilocus sequence typing

Abstract

Nocardia are aerobic Gram-positive saprophytes that are widely distributed in nature, but some species cause nocardiosis, especially opportunistic infections that affect immunocompromised patients mostly. In this study, we developed a multilocus sequence typing (MLST) scheme using seven housekeeping genes (gyrB, hsp65, secA1, rpoB, rpoA, recA, and trpB) for genotyping the most common clinical species, Nocardia farcinica (37 clinical isolates from the patients with nocardiosis and seven from animals in China and 15 reference strains). The results showed that using these loci could perform accurate identification among different species, and high discriminative power within the N. farcinica species. Of the 59 N. farcinica isolates, 44 sequence types have been identified; 32 STs covering 46 isolates could be assigned to six clonal complexes that encompassed most of the collected strains. The results showed that these strains displayed a sufficiently informative population structure using this method. Our study also provided a suitable approach for epidemiological studies of N. farcinica. A large clonal complex comprising 16 strains was identified, and was notable for its wide distribution and host adaptation. This complex should be monitored closely and merits further study.

Susceptibility profiles of Nocardia spp. to antimicrobial and antituberculotic agents detected by a microplate Alamar Blue assay

“…In addition, both the diagnosis of nocardial pneumonia and the widely used SXT prophylaxis may result in resistance; thus, individualized treatment must be based on the results of in vitro drug susceptibility tests. However, data on antimicrobial susceptibility have lagged behind advances in taxonomy: species that are isolated less frequently in the clinical laboratory have not been systematically tested, and only a few reports provide data on newer antimicrobials 1 4 .…”

A Primary Cutaneous Nocardiosis of the Hand

“…In a specialized laboratory analysis, 16S rDNA, multilocus sequence typing (MLST) using housekeeping genes for genotyping, or matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is employed for species identification [ 6 - 9 ]. Unfortunately, molecular assays were not available in our case.…”

Two chronically misdiagnosed patients infected with Nocardia cyriacigeorgica accurately diagnosed by whole genome resequencing

“…However, microbiological detection of Nocardia spp. is time-consuming, due to their slow growth, it usually takes several days until they are identified ( Du et al., 2016 ) and experienced microbiologists are required. Because of the complex colony morphological features of Nocardia spp., including ranging from smooth to rough with clear margined to irregular colonies, various colors, the presence of fragmenting hyphal forms and characteristic presence of short chain spores ( Dhakal et al., 2019 ), it is difficult to differentiate them by bacterial morphological examination.…”