Siderophores secreted by nonfermentative negative bacilli such as Pseudomonas aeruginosa are capable of increasing rates of resistance to carbapenem antibiotics. Furthermore, the resistance of these isolates to antibiotics has been enhanced by producing siderophores, and their frequencies have erratic patterns. We studied the outbreak of P. aeruginosa strains and their antibiotic patterns in different clinical samples. In this descriptive cross-sectional study, 100 P. aeruginosa samples were isolated from different clinical specimens at the 5th Azar Hospital, Gorgan, Iran, in 2017. These strains were identified by biochemical tests, and their antibiotic resistance patterns were measured via the disc diffusion method. Next imipenem and EDTA-imipenem (10-30 μg) antibiotics were employed for the detection of siderophores. Amongst 100 P. aeruginosa samples, 31 isolates (31%) were siderophore carriers. The frequency of this enzyme among specimens was as follows: 56.2% in burn wounds, 36.4% in urine, 22.2% in respiratory secretion, 19.4% in blood and 16.7% in wounds (p > 0.05). Moreover, P. aeruginosa isolates producing siderophores had the highest range of resistance to ciprofloxacin (47.6%), gentamicin (46.7%), ceftazidime (34.9%), nalidixic acid (34.3%), amikacin (34.1%) and cefotaxime (31.6%). The prevalence of siderophore producers, and especially their antibiotic patterns have no specific algorithms; in addition, an antibiogram is recommended to identify the most effective antibiotics against those isolates.
Keywords: Antibiotic resistance; Pseudomonas aeruginosa; clinical; siderophore.