Isolation and Identification of Nocardia Species from Soil Samples according to Comparison of Three Methods

Aerobic Actinomycetes, especially Nocardia are of the most common pathogens of systemic infections in worldwide. It is seen from skin infections caused by trauma in normal-immune system host to severe lung diseases or diseases of the central nervous system in patients with immune deficiency. Nocardia species (spp.) are soil-indwelling bacteria. This study aimed to compare three phenotypic methods for isolation and identification of Nocardia spp.

In this study, 60 soil samples were collected from areas of agricultural lands, gardens and around some of the hospitals with different soil temperature and pH in Isfahan, Iran. In order to isolation of Nocardia spp. from soil, three different methods were studied: Paraffin baiting method (McClung's carbon free broth with paraffin bait), Paraffin coated slides, and Slip-burid method.

Paraffin baiting method was surveyed on 10 soil samples and no results were gained. Paraffin coated slides was surveyed on 4 soil samples (same soil samples) but no results were attained. So, slip-burid method of isolation was tested. In this method, 15 out of 60 soil samples (25%) were positive for Nocardia spp. and colonies were suspected to Nocardia spp.

In this study, slip-burid method found to be more effective for Nocardia spp. Isolation.