Streptomyces Identified in Damp Indoor Spaces
The number of bacteria in the indoor air are frequently higher than mold spores. Thus, several studies have reported the identification of both Gram positive and Gram negative bacteria in indoor environments, Actinobacteria and, in particular, Streptomyces species, are present in the indoor environments.
The identification of these organisms is briefly discussed below.
The Gram-positive bacteria isolated from water-damaged building materials include species of Arthrobacter, Bacillus, Gondona, Micrococcus., Mycobactetiurn, Paenibacillus and Streptomyces (see Peltola, et a1,1001; Anderson et al, 1997).
The Streptomyces present in water-damaged building materials are diverse and include strains of the following species: iividans, anuiatus, diastatirus, aibidofiavusi virginiae and thermovulgaris (Pietarinen et al, 2008; Rintala et al, 2002).
Of the Streptomyces species, S. californicus has been shown to produce toxins that are very potent inducers of inflammatory cytokines in vitro and in a mouse model.
Streptomyces species produce the toxin, Valinomycin, which is a mitochondrial toxin and induces an inflammatory response in vitro. Moreover, Rintala et al, 2004 described the presence of Streptomyces species in house dust of water-damaged homes.
The four species, albidoflavus, virginiae, annula us, halstedii, and diastaticus were more plentiful than in undamaged homes.
In addition, the authors reviewed the literature on the subject of indoor bacteria. The review cited literature that identified Streptomyces, other Actinobacteria, as well as negative bacteria in these environments.
Health Effects of Streptomyces and Thermo Actinomycetes
Streptomyces species are considered as saprophytic bacteria present in soil and decaying organic matter. However, they are found in water-damaged buildings where the occupants have become ill. The genus is considered an opportunistic pathogen causing infection.
Streptomyces can cause the formation of mycetoma. Mycetoma are granulomatous lesions of the skin but also can be systemic (Martin et al, 2004; Develoux etal, 1988; Develoux et al, 1995). They are most common in tropical environments.
Infections have been reported in both immune-compromised and immune-competent patients. The identified species are maritmus, olivadeus, albus, nobilis, parvulus, humidus, pilosus, indigofetus and herbaricolor.
The infections include septicemia, pneumonia, brain abscess, peritonitis, pericarditis, endocarditis, knee, lung abscess and intraveneous catheters (Kapadia, et al, 2007). A brain abscess following skull penetration trauma has been reported along with isolates of additional Actinobacteria (Rose et al, 2008).
Other cases reported in the literature are neonatal infection (Werder et al, 1973), septicemia with thrombosis (Carey et al, 2001; Ghanem et al, 2007) and silicone breast implant (Manteca et al, 2009).
Streptomyces infections can lead to the development of mycetoma.
Lung Disease Associated Mesophilic and Thermo Actinomycetes
Thermophilic Actinomycetes are cultured at an optimum temperature of 55 oC. Therefore, they are missed at culture temperature done at 37 oC by microbiology laboratories.
In addition, these bacteria are slow growing and are missed because cultures are not maintained for a sufficient period of time.
Hypersensitivity pneumonitis (HP) or extrinsic allergic alveolitis is a complex syndrome that has three types of conditions: acute (lasts 3-4 days), subacute (intermittent) and chronic. It is characterized by diffuse inflammation of the airways with noncaseating interstitial granulomas and mononuclear cell infilatration and may have centrilobular fibrosis.
The common names associated with HP are Farmer's Lung Disease, Grain Handler's Lungs, Humidifier/Airconditioner lung, Bird Breeder's Lung, Cheese worker's lung, Bagassosis and Malt worker's lung. The precipitating agent is an immune response to microbial antigens or molds and bacteria.
The bacteria identified to cause this condition in damp indoor spaces includes Streptomyces spp. and Thermoactinomyces spp. (Kampfer et al, 2005; Fenoglio et al, 2007; Roussel et al, 2005; Che et al, 1989; Kagen et al, 1981; Roberts et al, 1983; Hollingdale, 1975).