Evaluation of bacterial quality of Oreochromis niloticus samples of Lake Manzala, Egypt

Abstract

The present study aimed to investigate bacterial quality of tilapia fish (Oreochromis niloticus) and evaluate the hygienic health hazard of fish contaminated with some food borne pathogens. Bacteria were isolated from intestine, gills and flesh of Oreochromis niloticus collected from Lake Manzala during two seasons; winter and summer, 2017. Microbiological studies was applied for all samples as total viable bacteria, total coliform, faecal coliform, faecal streptococcus and examined for the presence of Pseudomonas sp. Results show that total viable bacterial count mean was highest in intestine 222 x 10 4 CFUg-1 in summer. Total coliform count mean was highest in intestine 425 x 103 CFUg-1 in summer. Faecal coliform count mean was highest in gills 90 x 10 2 CFUg-1 in summer. Faecal streptococcus detected in fish organs only in summer. P. aeruginosa count mean was highest in intestine 185 x 10 2 CFUg-1 in summer. Molecular identification of suspected colonies was as DNA extraction, PCR technique using ISSR protocol and sequencing, using the nucleotide sequences of the genes for 16S rRNA revealed different strains of Pseudomonas aeruginosa. All isolates were tested for resistance to 10 groups of antibiotics namely Tetracycline (10μg), Gentamicin (10μg), Ampicillin (10μg), Trimethoprim/Sulphamethoxazole (25μg), Vancomycin (30μg), Erythromycin (15μg), Ciprofloxacin (30μg), Chloramphenicol (30μg), Amoxicillin (10μg) and Rifampicin (5μg) using Kirby-Bauer disc diffusion method. The results showed high frequency of multi-drug resistance to many antibiotics, particularly penicillin, ampicillin and chloramphenicol. Therefore this fish species caught from the Lake Manzala may pose health hazards to human and the whole ecosystem.

Phytoplankton and Bacterial Dynamics Related to the Physicochemical Characteristics of Manzala Lake Water, Egypt

“…Most previous studies showed that the lowest numbers of the bacterial indicators were recorded at sites opposite the Boghazes (which feed the lake with saline water from the Mediterranean Sea), whereas the greatest bacterial indicators were found mostly at the sites close to the discharge points of polluted and untreated water via the drains. This data interpretation agrees with the results obtained by Tahoun (2016), Ibrahim (2017), andEl-ghannam et al (2020).…”

Evaluation of bacteriophage to reduce Escherichia coli contamination in different food samples

“…Catalase test was carried out by using a small number of bacteria collected from a fresh-isolated 18-24 hour colony to a drop of 3% H 2 O 2 . Catalase positive results are evident by immediate effervescence and bubbles formation of O 2 [36] [37]. A single pure colony from a freshly isolated bacterial culture was taken up and slowly mixed in droplets of distilled water for the Oxidase Test.…”