الفهرس 
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Abstract
Summary
The present work was conducted over a period of 24 months from July 2016 to July 2018 on 246 endotracheal aspirate and sputum specimens collected from patients admitted at the chest ICU of Assiut University Hospitals who developed VAP and HAP, respectively.
Out of the 246 samples, 131/246 (53.2%) staphylococci strains were isolated. Staphylococci strains included 51/246 (20.7%) CoNS and 80/246 (32.5%) S. aureus strains.
from all collected 80 S. aureus strains, 49 (61.25%) were isolated from endotracheal aspirate samples and the remaining 31 (38.75%) were isolated from sputum samples.
Seventy seven (96.25%) of the 80 S. aureus isolates were identified as MRSA by culture on ORSAB, cefoxitin disk and molecular detection of mecA gene.
The studied isolates showed the highest sensitivity rates to vancomycin (75%), as detected by E-test .
The coa gene was amplified in 80 different S. aureus isolates. The size of the products ranged from 576 to 810 bp, and these products showed 5 different types of band patterns.
The spa gene was amplified in 80 different S. aureus isolates. The size of the products ranged from 240 to 1100 bp, and these products showed 3 different types of band patterns.
The most common coa, spa and combined coa/ spa genotypes detected among our S. aureus isolates causing VAP were C5 (405 bp and 810 bp) that was identified in 14/49 (28.5%), S2 (240 bp and 360 bp) that was identified in 28/31 (57.1%) and C2/ S2 in 10/49 (20.4%) of the isolates, respectively.
The most common coa, spa and combined coa/ spa genotypes detected among our S. aureus isolates causing HAP were C3 (729 bp) that was identified in 10/31(32.2%), S2 (240 bp and 360 bp) that was identified in 18/31 (58%), C3/ S2 in 7/31 (22.5%) of the isolates, respectively.
Conclusion
Our study concluded that:
• S. aureus is the second most common cause of nosocomial pneumonia in the Chest ICU, after Klebsiella spp.
• There is high resistance rate against different antimicrobial agents among S. aureus isolates ranging from 25% to 100%. This will make it difficult to treat different infections at our hospitals.
• There are 5 Coa genotypes with band sizes ranged from 405 to 810 bp. The most common coa genotype detected among our S. aureus isolates was C5 (405 bp and 810 bp) that was identified in 22/80 (27.5%) of the isolates, followed by C4 (810 bp) that was identified in 18/80 (22.5%) of the isolates.
• There are 3spa genotypes among S. aureus isolates with band sizes ranged from 240 to 1100 bp. The most common spa genotype detected among our S. aureus isolates was S2 (240 bp, 360 bp) that was detected in 46 (57.5%) of the isolates, followed by S3 (240 bp, 360 bp, 1100 bp) that was identified in 25 (31%) of the isolates.
• Certain coa (C4, C5) and spa (S2, S3) genotypes are associated with high resistance to most of the tested antibiotics and with certain risk factors for nosocomial pneumonia.
• Molecular typing (coa and spa genotyping) are important tools for better understanding of the epidemiology of S. aureus nosocomial pneumonia. Also, it contributes to the control, prevention and treatment of HAP and VAP caused by S. aureus.