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عزل وتشخيص عاثي المكورات العنقودية الذهبية وتقييم نشاطه المضاد للبكتيريا == Isolation and Characterization of Staphylococcus aureus Bacteriophage and Evaluation of Its Antibacterial Activity
Author name:
عارف عباس غايب
Supervisor name:
ابراهيم عبد الله احمد | حامد خلف احمد
General topic:
Biology
Specific topic:
Microbiology - Viruses
Degree:
Master
University:
Al-Nahrain University - College of Biotechnology - Department Of Biotechnology
Language:
English
University location:
Baghdad
Key words:
- phage Rih21
- phage genome analysis
- bacteriophage
- S. aureus
- Staphylococcus aureus phage Rih21
- staphylococcus aureus
- bacteriophage
- novel bacteriophage
- Staphylococcus phage Rih21
- MRSA
First pages:
T86806 - p.pdf
Abstract:
The antimicrobial therapy, in the long term, is expected to become ineffective against Staphylococcus aureus (S. aureus) due to its ability to produce new and more virulent strains. Bacteriophages are known to fight bacteria for a very long time and have the ability to adapt to the developing bacteria. In this study, 129 clinical specimens were collected from different places in Baghdad and from different clinical sources during the period from October 13, 2020, to January 26, 2021. Only 45 isolates showed cultural (mannitol salt and blood agar) and biochemical (catalase, coagulase and oxidase test) characteristics that were specific to S. aureus. The identity of S. aureus isolates was further confirmed by using specific primers for amplification and sequencing of the S. aureus thermonuclease (nuc) gene, and the blast result of sequences in the NCBI database was 99% to 100% identical to S. aureus species. Also, the S. aureus isolates were tested for sensitivity of different types of antibiotics, and results revealed that: all S. aureus isolates demonstrated high levels (100%) of resistance against the cefoxitin, penicillin, and ceftazidime. It also showed intermediate levels of resistance against tetracycline 55.56% (25/45 isolates), and azithromycin 46.67% (21/45 isolates), and the lowest levels of resistance was against the erythromycin 44.44% (20/45 isolates), rifampin 17.78% (8/45 isolates), trimethoprim/sulfamethoxazole 17.78% (8/45 isolates), clindamycin 15.56% (7/45 isolates), gentamicin 13.33% (6/45 isolates) and ciprofloxacin 11.11% (5/45 isolates). also found that no antibiotics tested in this study were able to kill all S. aureus isolates, therefore all isolates tested in this study were classified as Methicillin-resistant Staphylococcus aureus. From the hospital waste-water, a novel bacteriophage was isolated and characterized. The enrichment method was used for isolation of Staphylococcus aureus bacteriophage and six rounds of purification based on the plaque assay were used to purify a single type of bacteriophage against S. aureus clinical isolates. According to characterization properties, this bacteriophage belongs to the Siphoviridae family and can form a halo around the phage plaque. The maximum bacteriophage titer was recorded at 37°C and a pH of 7.2. The bacteriophage titers were decrease at 45°C, 50°C, and 55°C, until completely lost its activity at 60°C. This bacteriophage was completely inactivated at highly acidic (3, 4) and basic (10, 11) pH values and lost part of its activity at pH 5, 6, 8, and 9. This bacteriophage had a 44,789 bp linear double-strand DNA genome, and within the genome sequence, there are 61 genes, all of which are encoded into proteins. Although this bacteriophage does not have any virulence factors or antimicrobial resistance genes and had specific lytic activity against some antimicrobial resistance S. aureus clinical isolates. All the features mentioned above about this bacteriophage could make it a valuable antibacterial choice against antimicrobial-resistant S. aureus clinical isolates.
Full text:
56f24a73ad.pdf
Summary:
bb5385890c.pdf
References:
67d667ebac.pdf
