Isolation and Characterization of Nocardiae Associated with Foaming Coastal Marine Waters

Abstract

Nocardiosis is an infectious disease caused by Nocardia species that occurs worldwide, albeit more prevalently in tropical/subtropical regions. It can appear as either acute, subacute or as a chronic infection mostly with those with a compromised/weakened immune system. Inhalation of spores and or mycelium fragments is the main transmission route for developing pulmonary nocardiosis. In contrast, cutaneous nocardiosis usually occurs via direct contact. In the subtropical region of the Sunshine Coast in Australia foaming events with thick and persistent and orange-brown color foam have been observed during summer seasons in the near shore marine environments. This study reports the existence of nocardiae in these near shore marine environments by the use of a novel isolation method which used the gas requirements of nocardiae as a selective battery. A total of 32 nocardiae were isolated with the use of this novel method and subsequently conducted molecular identification methods confirmed that the isolates belonged to the genus Nocardia. Twenty-one isolates out of the 32 were closely related to N. nova strains MGA115 and one was related to CBU 09/875, in addition when compared with human pathogenic nocardiae twenty of the isolates were found to be related to N. nova strain JCM 6044. Isolates displayed varied resistance against some of the antibiotics tested when interpretation threshold recommended the Comite de L’Antibiogramme de la Societe Francaise de Microbiologie were used. The highest level of resistance against cefotaxime (n = 27) and ceftriaxone (n = 24). Some of the isolates (n = 6) that displayed resistance to selected antibiotics also possessed potential human pathogenic characteristics such as adherence and translocation through human long epithelial cells as well as displaying phage resistance (n = 26). They might thus present a potential public health risk if frequently encountered through exposure to aerosols generated by the foam as well as direct contact through a wound. Preventative measures to control the growth of nocardiae in such environments such as the control of pollutants, might prevent potential infections that might be caused by these bacteria in humans as well as in marine animals.

Epidemiology of Nocardia Species at a Tertiary Hospital in Southern Taiwan, 2012 to 2020: MLSA Phylogeny and Antimicrobial Susceptibility

“…Our finding of a decrease in the prevalence of clinically isolated Nocardia spp. in summer from 2012 to 2020 is in contrast to the findings of an Australian environmental survey of Nocardia species isolated during a 1-year period from the foaming marine waters of the Sunshine Coast region [ 28 ], which suggests that hot weather is conducive to the growth of Nocardia . However, more studies of the prevalence of Nocardia species among clinical samples per month are needed to gain insights into the correlation of climate change and the distribution of Nocardia spp.…”

Nocardia species distribution and antimicrobial susceptibility within Australia

“…10 Environmental sampling within Australia has demonstrated the presence of Nocardia on Australian native eucalypt and pines trees (Callitris preissii), 24,25 in rainwater tanks 26 and in marine foam (revealing a predominance of N. nova, with greater recovery during summer months). 27 It can also be found causing disease in cats, 28 dogs, 29 koalas 28 and farmed steer. 30 Environmental exposure to Nocardia has been cited as a public health risk.…”

Nocardia Brain Abscess in a Patient With Sarcoidosis

“…The Centers for Disease Control and Prevention (CDC) reported an estimated 500-1,000 cases of nocardiosis infection occurring yearly in the United States, with around 60% of these cases associated with immunocompromised patients [9]. Given that the bacteria is found in standing water and soil, farmers and swimmers have a high risk of exposure [9,10]. Systemic infections can occur through the hematogenous spread and are more frequently found in immunocompromised patients such as those with autoimmune diseases, cell-mediated immune defects, malignancies, or those on long-term steroids [1][2][3].…”