Stenotrophomonas maltophilia is an emerging pathogenic non-fermentative Gram-negative Bacillus
species. It has caused many nosocomial infections and can be isolated from various hospital wards and
healthcare facilities. Research has shown that most of its strains are inherently resistant to many antibiotics
and have multidrug resistance. This research intended to determine its occurrence frequency at some
Hospitals in shiraz, Iran. The present study was conducted in six months (from early spring to late summer
2019). Clinical samples (Blood, Urine and cerebrospinal fluid (CSF)) collected from 120 patients afflicted
with various infections. The samples were transferred to the Laboratory and subjected to microbiological
analysis. Identification of the isolates was carried out by phenotypic methods and Stenotrophomonas
maltophilia isolates verified using molecular methods. In total, various bacteria were isolated from 84
clinical samples. The isolates were Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae,
Stenotrophomonas maltophilia, Staphylococcus aureus and Pseudomonas aeruginosa. Stenotrophomonas
maltophilia was isolated from 17 (20.2%) positive samples and most of them were isolated from blood
samples. Our finding indicated that Stenotrophomonas maltophilia isolated more from blood samples follow
by CSF sample. In addition, our finding illustrated that Stenotrophomonas maltophilia can be considered as
the common nosocomial agent at hospitals in Shiraz, Iran.