Investigation of a pseudo-outbreak of Nocardia asteroides infection by pulsed-field gel electrophoresis and randomly amplified polymorphic DNA PCR

Nocardiosis from 1888 to 2017

The genus Nocardia is an aerobic bacterium, Gram-positive and catalase positive that is in Nocardiaceae family. This bacterium first described by Edmond Nocard in 1888 and is not in human commensal bacteria. To date, nocardiosis incidence is increasing due to increase population growth rate, increase in patients with immune disorder diseases and immunocompromised patients. We surveyed taxonomic position, isolation methods, phenotypic and molecular identification at the genus and species levels, antibiogram, treatment and epidemiology in the world from 1888 to 2017.

Molecular typing of a suspected cluster of Nocardia farcinica infections by use of randomly amplified polymorphic DNA, pulsed-field gel electrophoresis, and amplified fragment length polymorphism analyses

Randomly amplified polymorphic DNA (RAPD), pulsed-field gelelectrophoresis (PFGE), and amplified fragment length polymorphism (AFLP) analyses were used to investigate a possible outbreak of Nocardia farcinica. RAPD and PFGE analyses yielded irreproducible and unsatisfactory results, respectively. AFLP analysis seem to be a promising and welcome addition for molecular analysis of Nocardia isolates.

Clinical and laboratory features of the Nocardia spp. based on current molecular taxonomy

The recent explosion of newly described species of Nocardia results from the impact in the last decade of newer molecular technology, including PCR restriction enzyme analysis and 16S rRNA sequencing. These molecular techniques have revolutionized the identification of the nocardiae by providing rapid and accurate identification of recognized nocardiae and, at the same time, revealing new species and a number of yet-to-be-described species. There are currently more than 30 species of nocardiae of human clinical significance, with the majority of isolates being N. nova complex, N. abscessus, N. transvalensis complex, N. farcinica, N. asteroides type VI (N. cyriacigeorgica), and N. brasiliensis. These species cause a wide variety of diseases and have variable drug susceptibilities. Accurate identification often requires referral to a reference laboratory with molecular capabilities, as many newer species are genetically distinct from established species yet have few or no distinguishing phenotypic characteristics. Correct identification is important in deciding the clinical relevance of a species and in the clinical management and treatment of patients with nocardial disease. This review characterizes the currently known pathogenic species of Nocardia, including clinical disease, drug susceptibility, and methods of identification.

Characterization of Nocardia asteroides isolates from different ecological habitats on the basis of repetitive extragenic palindromic-PCR fingerprinting

Thirteen isolates of Nocardia asteroides from both soils and aquatic samples (lake and moat sediments, as well as scum from activated sludge), together with a type strain and two known clinical isolates of this species, were characterized by repetitive extragenic palindromic-PCR fingerprinting with the BOX-A1R primer. The resulting DNA fingerprint patterns proved to be strain specific, and cluster analysis distinguished the soil isolates, the aquatic isolates, and the known strains as being in separate groups.

Pulmonary Nocardiosis

Pulmonary nocardiosis is an uncommon but serious infection that is increasingly found in immunosuppressed persons, especially transplant recipients and persons with AIDS. The Nocardia species are denizens of soil and decaying plants that gain entry to humans through inhalation or inoculation. Pulmonary nocardiosis typically presents as an acute to subacute necrotizing pneumonia, with a variable clinical picture. Metastatic infections of the brain and subcutaneous tissues are common complications. Most clinical laboratories can isolate these microorganisms, but final speciation may be a challenge and antimicrobial susceptibility testing is especially difficult because of the slow rate of growth of Nocardia species. Full identification of species and susceptibility testing is important because of the epidemiologic implications and the difficulties of successfully treating these infections in immunosuppressed patients. Sulfonamides, including trimethoprim-sulfamethoxazole, remain the most reliable antimicrobials. Many alternative agents are active against Nocardia in vitro, but clinical data are limited.

Use of randomly amplified polymorphic DNA as a means of developing genus- and strain-specific Streptomyces DNA probes

We have analyzed 20 randomly amplified polymorphic DNA (RAPD) primers against 36 Streptomyces strains, including 17 taxonomically undefined strains, 25 nonstreptomycete actinomycetes, and 12 outgroups consisting of gram-positive and -negative species. Most of the primers were useful in identifying unique DNA polymorphisms of all strains tested. We have used RAPD techniques to develop a genus-specific probe, one not necessarily targeting the ribosomal gene, for Streptomyces, and a strain-specific probe for the biological control agent Streptomyces lydicus WYEC108. In the course of these investigations, small-scale DNA isolations were also developed for efficiently isolating actinomycete DNA. Various modifications of isolation procedures for soil DNA were compared, and the reliability and specificity of the RAPD methodology were tested by specifically detecting the S. lydicus WYEC108 in DNA isolated from soil.

Nocardia thyroiditis: unusual location of infection

Nocardia asteroides complex is an important opportunistic agent in immunocompromised hosts. Usually, primary pulmonary infection occurs and is followed by dissemination of the pathogen to the central nervous system and soft tissues. As described in the literature, almost every organ can be infected, but to our knowledge, Nocardia has been described as a pathogen responsible for thyroid abscess in only one report, which was published in 1993. The present report is the second case report of Nocardia thyroiditis. The patient was under immunosuppressor treatment following a combined liver-kidney transplant and presented with a preexisting nodular goiter which was probably a predisposing factor to the start and development of the thyroid infection.

A standardized protocol for the rapid preparation of bacterial DNA for pulsed-field gel electrophoresis

A rapid method for the preparation of bacterial DNA for pulsed-field gel electrophoresis was developed for Gram-positive and Gram-negative bacteria. This method was accomplished by reducing the time for the cell lysis reaction, restriction endonuclease digestion, and electrophoresis to 1, 1.5, and 18 h, respectively. The whole procedure from the initial bacterial culture plate to the final analysis of restriction fragments can be completed within 24 h. This rapid method was successfully achieved for Staphylococcus aureus, Enterococcus faecalis, Neisseria gonorrhoeae, Salmonella typhimurium, Serratia marcescens, and Stenotrophomonas maltophilia.