Prevalence of Tetracycline Resistant Bacteria and its Related Resistant Gene(s) in Different Water Sources

Abstract

Nile River is considered the most vital source of freshwater for human, animal and plant in Egypt. Increasing of River Nile usage in Egypt lead to be more susceptible to contamination. Tetracycline-resistant bacteria can be transmitted to humans directly by contact with contaminated water. Therefore, the presence of tetracycline-resistant bacteria is increasing the probabilities of water contamination levels. Water samples were evaluated by using most probable number (MPN) of fecal coliform bacteria. MPN of water samples were ranged from 0.17 x102 to 0.9x102 CFU/100 ml. A hundred and fifty Gram negative bacterial isolates were isolated from different water samples from two different locations (El-Zamalek and Rod EL-Farag) in Cairo city. A seventy isolates out of 150 bacterial isolates (46.6%) were resistant to (16 mg/l) tetracycline. Only 31 (44.2%) were selected due to their resistance to (32 mg/l) tetracycline for identification and to detect tet genes by polymerase chain reaction (PCR). All selected isolates were identified according to biochemical characterization and the 16S rDNA sequence techniques. The 16S rDNA sequences of the bacterial isolates were submitted to the NCBI database (accession No. MH266225- MH266252), accession no.MH423704-MH423705) and (accession No.MH469556). Of the 31 identified bacteria, 41.9 % (13 of 31) carry tet A gene, 74.2% (23 of 31) carry tet D gene, while 12.9 % (4 of 31) carry tet M gene. Three tested tet genes were not detected (tet B, tet C and tet O). Twenty-one identified bacteria (67.7%) harbored a single tet gene, five identified bacteria (16.1%) harbored two different tet genes while three identified bacteria (9.6 %) harbored three different tet genes while two identified bacteria did not detect any type of the tested tet genes. The maximum detected tet genes combination in some strains were three, tet A, D and M. It could be concluded that Nile water is a reservoir of tetracycline resistant bacteria that have tet genes as result of the anthropogenic inputs, overuse of the antibiotic and dumping of untreated effluents which indicates the possibility that tetracycline resistant bacteria and their molecular resistance determinants may serve as bioindicators of water environmental quality consistently influenced by anthropogenic activities.