Collection and Identification of P. aeruginosa Isolates from Different Clinical Specimens

In this study, 133 P. aeruginosa strains were isolated from burned patients admitted to two major university hospitals in Tehran and Isfahan provinces in Iran from May to October 2016. The strains were isolated from wound, tissue (deep wound), blood (patients with both wound and systemic infections), and genitourinary catheters (patients with both wound and urogenital infections) of burned patients (with Degree III burn) and identified in the hospitals laboratories using biochemical tests. All patients fulfilled the criteria of nosocomial infection with no initial infection prior to admission.

The isolates were transferred to the laboratory of Tarbiat Modares University and subjected to re-identification and confirmation by phenotypic tests including Gram staining, catalase, oxidase, citrate, triple sugar iron agar (TSI), oxidative-fermentative test, growth at 42°C, methyl red/Voges Proskauer (MRVP), sulfur indole motility test (SIM), and pigment production on Muller Hinton agar (MHA)20 and further confirmed by molecular methods using specific polymerase chain reaction (PCR) for 16s rDNA of P. aeruginosa. The primer sequences were species-specific and encompassed variable regions (V2 and V8) of 16S rDNA.21 All culture media were purchased from Merck, Germany, and in all assays, P. aeruginosa ATCC27853 was included as standard control.