The medically important aerobic actinomycetes: epidemiology and microbiology

Abstract

The aerobic actinomycetes are soil-inhabiting microorganisms that occur worldwide. In 1888, Nocard first recognized the pathogenic potential of this group of microorganisms. Since then, several aerobic actinomycetes have been a major source of interest for the commercial drug industry and have proved to be extremely useful microorganisms for producing novel antimicrobial agents. They have also been well known as potential veterinary pathogens affecting many different animal species. The medically important aerobic actinomycetes may cause significant morbidity and mortality, in particular in highly susceptible severely immunocompromised patients, including transplant recipients and patients infected with human immunodeficiency virus. However, the diagnosis of these infections may be difficult, and effective antimicrobial therapy may be complicated by antimicrobial resistance. The taxonomy of these microorganisms has been problematic. In recent revisions of their classification, new pathogenic species have been recognized. The development of additional and more reliable diagnostic tests and of a standardized method for antimicrobial susceptibility testing and the application of molecular techniques for the diagnosis and subtyping of these microorganisms are needed to better diagnose and treat infected patients and to identify effective control measures for these unusual pathogens. We review the epidemiology and microbiology of the major medically important aerobic actinomycetes.

Occurrence of plasmids in pathogenic strains of Nocardia

“…Other investigators have suggested that N. farcinica infection is characterised by higher rates of disseminated disease, antimicrobial resistance and mortality than other Nocardia spp. [27].…”

Rhodococcus equi isolation from sputum of patients with suspected tuberculosis

“…The identifica-tion of R. equi was based on microscopic observation of bacteria subjected to Gram's and Ziehl-Neelsen staining (Ballows et al 1991) and phenotypic biochemical tests described in the Manual of Systematic and Clinic Microbiology (Ballows et al 1991, Holt et al 1994, Murray et al 1999, Koneman et al 2000, Mac Faddin 2000. Gordon's base culture medium was used for acid production in carbohydrate tests (McNeil & Brown 1994). The CAMP test was performed as described by Bille and Doyle (1991), using L. ivanovii ATCC 19119 and R. equi ATCC 6939 as standard strains.…”

Scalp Abscess Due to Streptomyces cacaoi subsp. cacaoi , First Report in a Human Infection

“…While Streptomyces species are not a common cause of deeply invasive human infections, other than mycetoma attributed to Streptomyces somaliensis, there are increasing reports from nonmycetomic invasive infections (6). Recent reports include the following: Kapadia et al (4) reported on 47 patient isolates and found six invasive infections in the study group.…”