EC Microbiology

Objectives: This study aimed to investigate the prevalence, distribution, and antimicrobial resistance profiles of Pseudomonas species in diverse aquatic environments across Sudan between 2019 and 2021.

Methods: A total of 144 water samples were collected from ten sites including rivers, lakes, groundwater wells, and coastal areas in Sudan. Isolation and identification of Pseudomonas species were performed using selective media (cetrimide agar) and standard biochemical assays following Bergey's Manual of Systematic Bacteriology. Antimicrobial susceptibility was tested against 12 antibiotics using the disk diffusion method according to CLSI (2020) guidelines. Double-disc synergy testing was employed to assess combination effects.

Results: Pseudomonas aeruginosa was the dominant species, comprising 70.3% of all isolates. The highest prevalence was recorded in freshwater sources including the Blue Nile (92%), Atbara River (93.7%), and groundwater wells (72 - 88.8%), while minimal recovery (< 10%) was observed in saline Red Sea samples. Antimicrobial testing revealed complete resistance (100%) to ampicillin-sulbactam, cefotaxime, and co-trimoxazole across all regions, with high resistance to tetracycline (up to 97%). Aminoglycosides (amikacin, gentamicin) and fluoroquinolones (ciprofloxacin, levofloxacin, ofloxacin) remained fully effective against most isolates. Synergistic interactions were detected between tazobactam and levofloxacin, showing a 33% increase in inhibition zones.

Conclusion: This study demonstrates a high prevalence of multidrug-resistant Pseudomonas species, particularly P. aeruginosa, in Sudanese aquatic systems. The extensive resistance to β-lactams and tetracycline, coupled with preserved susceptibility to aminoglycosides and fluoroquinolones, underscores the urgent need for antimicrobial stewardship, continuous surveillance, and implementation of water safety measures to protect public health.

Keywords: Nile River; Pseudomonas spp; Antibiotic Susceptibility; Pseudomonas aeruginosa; Prevalence; Multidrug Resistance

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