Mycopathologia 137: 159–163, 1997. 159 c 1997 Kluwer Academic Publishers. Printed in the Netherlands. Nocardia asteroides in the Soil of Kuwait Z.U. Khan, L. Neil, R. Chandy, T.D. Chugh, H. Al-Sayer , F. Provost and P. Boiron Departments of Microbiology and Surgery, Faculty of Medicine, Kuwait University, Kuwait and Mycology Unit, National Reference Center for Mycoses, Antifungal Agents and Actinomycetes, Pasteur Institute, Paris, France Received: 14 January 1997; accepted in revised form 2 July 1997 Abstract A pilot study was undertaken to determine the occurrence and distribution of pathogenic nocardiae in Kuwaiti soil. A total of 102 soil samples collected from two localities were investigated by the paraffin bait technique. Nocardia asteroides was the only species isolated from 42 (41%) soil samples. None of the isolates fulfilled the criteria required for identification of N. farcinica or N. nova. Thirty one (73.8%) isolates showed equivalent growth at 45 C and 35 C, 17 (40.4%) isolates utilized acetamide for carbon and nitrogen requirements and 3 (7.1%) isolates showed delayed arylsulphatase activity. Only a solitary isolate was resistant to cefamandole. Soil samples originating from the Kuwait University Campus, Shuwaikh, which were rich in humus/organic matter, were more productive for N. asteroides (67%) than the samples which were devoid of it but were mixed with crude oil (39%). Sand samples that lacked organic matter and crude oil samples were least productive of N. asteroides. These preliminary findings do not suggest that massive oil contamination of soil in the Ahmadi oil field area during the Gulf war promoted the natural occurrence of N. asteroides. However, isolation of N. asteroides in as many as 41% of the soil sample is a significant observation warranting further epidemiologic studies including its possible role in the operation desert storm sickness syndrome. This is the first report on the natural occurrence of N. asteroides in Kuwait. Key words: Nocardia asteroides, nocardiae in soil, crude oil contamination, natural occurrence Introduction The members of the genus Nocardia are widely dis- tributed in terrestrial habitats [1]. They are aerobic, catalase-positive actinomycetes that form rudimentary to extensive branching hyphae which tend to fragment into coccobacillary forms. The genus currently encom- passes 13 described species [2] but only seven of them namely N. asteroides, N. brasiliensis, N. farcinica, N. nova, N. otitidiscaviarum, N. pseudobrasiliensis and N. transvalensis are known to cause human infections [3,4]. They cause a variety of suppurative infections in humans mostly as opportunistic pathogens compli- cating debilitating primary diseases such as, leukemia, lymphoma and other neoplasms, or in patients receiv- ing immunosuppressive therapy for a variety of condi- tions including organ transplantation [5]. Little information is available on the occurrence and distribution of pathogenic nocardiae in Kuwaiti soil. Taking into consideration that nocardiae have the property to utilize hydrocarbons as a sole source of energy, it was assumed that some of the desert areas of Kuwait that were contaminated with crude oil dur- ing the Gulf war, might now be serving as a selective natural substratum for the growth of these potentially pathogenic microorganisms. This assumption prompt- ed the present study. Materials and methods Collection and processing of soil samples. One hun- dred and two soil samples from two locations, the Ahmadi oil field area and the Kuwait University Cam- pus, Shuwaikh, were collected in polythene bags after removing about 5 cms of the top layer of the soil. The samples were stored at 20 C until processed for iso- lation of nocardiae. The scheme for the processing of soil samples for isolation of Nocardia spp. is shown in Figure 1. Briefly, a representative 10 gm quantity