Antibiotic Resistance of Pathogenic and Bacterial Contaminants Isolated from Fish Pond Wastewater in Bechar Province, Southwestern Algeria

Background: This study investigates bacterial contaminants and pathogenic species isolated from fish pond wastewater (FPWW) in Bechar province, Southwestern Algeria and assesses their antibiotic resistance propfile. Methods: A total of 21 FPWW samples were analyzed using different culture media to isolate bacterial contaminants via the membrane filter technique. Following purification, all bacterial isolates were identified through biochemical tests and subjected to susceptibility testing by the Kirby-Bauer disc diffusion method on Mueller-Hinton (MH) agar and the broth microdilution technique. Antimicrobial residue detection was also carried out using the microbiological tube test method (MTT). Result: We successfully isolated 68 bacterial isolates, classified into six bacterial groups: non-Enterobacteriaceae (41.18%), Enterobacteriaceae (38.24%), Streptococcaceae (8.82%), Pseudomonadaceae (7.35%), Erwiniaceae (2.94%) and Neisseriaceae (1.47%). According to the Chi-Square Goodness-of-Fit Test, this distribution was highly significant (p less than 0.001). The isolated species included Aeromonas hydrophila hydrophila, Streptococcus spp., Enterobacter spp., Serratia spp., Escherichia coli, Citrobacter spp., Klebsiella spp., Plesiomonas shigelloides, Kluyvera spp., Pseudomonas aeruginosa, Pantoea spp., Chromobacterium violaceum, Salmonella choleraesuis and Vibrio spp. Susceptibility testing of the bacterial contaminants revealed variable responses among the strains, with increased resistance to β-lactam antibiotics. Multidrug resistance results showed that 17 strains (25%) exhibited resistance to three to six different antibiotic classes, with Multiple Antibiotic Resistance (MAR) indices ranging from 0.28 to 0.68. The variability in MAR indices among bacterial groups was statistically significant (ANOVA, p = 0.0498). Furthermore, no growth-inhibiting substances were detected in the wastewater samples using the MTT method.