الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
MRSA became endemic today in hospitals worldwide. It demonstrates a unique ability to quickly resist several antimicrobial agents as linezolid, vancomycin, teicoplanin, and daptomycin which led to explore a new approach for MRSA treatments in wound and burns to increase efficacy and decrease sides effects of available antibiotics.
AgNPs had been investigated extensively to evaluate their utility as a valuable candidate for usage in conjunction alongside vancomycin to boost its antibacterial potency. Moreover, it could represent a promising weapon in the fight against biofilm forming MRSA by preventing the adhesion of bacterial cells to surfaces or by damaging the intermolecular force.
The present study aimed to:
1. Isolate and identify MRSA from burn and wound infections.
2. To detect the production of biofilm among methicillin resistant Staphylococcus aureus isolates.
3. To measure the minimal inhibitory concentration and minimal bactericidal concentration of silver nanoparticles and vancomycin.
4. To determine the antimicrobial effect of combination of vancomycin and silver nanoparticles on methicillin resistant Staphylococcus aureus isolates.
5. To detect the effect of each silver nanoparticles, vancomycin, and combination of both on biofilm production.
This in-vitro experimental study was carried out during the period from October 2019 to October 2020. It enrolled 42 MRSA isolates from clinical samples obtained from patients attending or admitted to AMUH with wound and burn infections.
Wound and burn samples were cultured on BA, MacConkey’s agar and MSA plates. Isolates were subjected to standard microbiological procedures for identification. MRSA screening was conducted using cefoxitin disc susceptibility test.
The production of biofilm was detected by congo red agar plates and tissue culture plates. MICs of vancomycin and AgNPs were determined by broth microdilution assay. The effect of combination of vancomycin with AgNPs was evaluated by checkerboard method.
The results of the present study could be summarized as follows:
1. Most of the patients with MRSA infections were female (54.76%), and in the age group of 36 < 56 years (54.76%).
2. The majority of MRSA infections were from wounds 33 (78.58%) out of 42 infections, while the remaining 9 (21.42%) were from burn infections. The most common wound infection was diabetic foot infection (40.48%).
3. Sixteen (38.10%) out of 42 MRSA isolates were biofilm producer.
4. Majority of MRSA isolates were moderate producers, 12 (75.00%) out of 16, whereas the remaining 4 isolates were evenly distributed between 2(12.50%) strong and 2(12.50%) weak producers.
5. The majority of biofilm producing strains, 14 (87.50 %) out of 16, were isolated from diabetic foot infections. One of the strong biofilms producing strains was from wound infections and the other one was from burn infections. All week and moderate biofilm producer strains were from wound infections.
6. The majority of wound and burn infections were due to vancomycin intermediately resistant MRSA (54.55% and 77.78%, respectively). Five (11.91%) out of 42 MRSA isolates were vancomycin resistant, 4 from them were isolated from wound infections, and only one from burn.
7. Five (31.25%) out of 16 biofilm producing MRSA isolates were vancomycin resistant, whereas the remaining 11 (68.75%) showed intermediate resistance. On the other hand, none of the 26 non-biofilm producing MRSA strains was resistant to vancomycin, 12 (46.15%) out of them were sensitive to vancomycin, and the remaining 14 (53.85%) showed intermediate resistance.
8. MIC of AgNPs against 20 (47.62%) out of 42 MRSA isolates was 25 µg/ml., whereas MIC against the remaining 22 (52.38%) isolates was 50 µg/ml. MBC of AgNPs ranged from 50-100 µg/ml.
9. Greatest enhancement of activity of vancomycin was observed at AgNPs concentrations of MICAg/2 and MICAg/4.
10. Enhanced activity of vancomycin combined with AgNPs concentrations of MICAg/8 and MICAg/16 were still observed but less obvious.
11. The combination of vancomycin with AgNPs was synergistic against 80.95% of MRSA isolates and additive against 14.29% and indifferent in 4.76%.
12. Biofilm treatment using combination of AgNPs and vancomycin had the highest biofilm inhibition percentage (69.59%), followed by AgNPs treatment (50.37%). The least biofilm inhibition percentage was encountered using vancomycin treatment alone (31.58%).
It could be concluded from the present study that:
1. The majority of MRSA isolates were from diabetic foot infections.
2. The majority of MRSA isolates were moderate biofilm producers, and intermediately resistant to vancomycin.
3. AgNPs concentrations (MICAg/2 and MICAg/4) strongly enhanced the activity of vancomycin against MRSA isolates.
4. The combination of AgNPs with vancomycin was synergistic.
5. The combination of AgNPs with vancomycin had the highest biofilm inhibition percentage.
Recommendations
1. Healthcare facilities should implement infection control programs to restrict the spread of MRSA infections.
2. Combining AgNPs with vancomycin offers a valuable alternative for combating drug resistance.
3. Additional studies should be conducted to explore the antibacterial potential of AgNPs in-vivo.
4. Extensive research is needed to determine the precise minimum inhibitory concentration of AgNPs on different bacterial isolates.
5. Combining AgNPs in topical application for burn and wound infections would provide economic benefits.