الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
S. aureus is one of the most common pathogens, which is responsible for versatile infections from minor skin infections to deep life-threatening ones. Since it has the ability to develop antibiotic resistance by different resistance mechanisms, its treatment has become more challenging and treatment options are diminishing with time.
MRSA is one of the most significant endemic hospital and community acquired pathogens. Its increasing trend was accompanied by increased use of vancomycin -the drug of choice for treatment of MRSA infections. Strains of S. aureus with reduced susceptibility or full resistance to vancomycin started to emerge in different regions of the world.
The present study aimed to:
1- Identify the bacterial profile of infections among patients in Kafr El-Dawar General Hospital.
2- Isolate and identify S. aureus strains from nasal swabs from patients.
3- Perform antibiotic susceptibility testing using disc diffusion for all S. aureus isolates.
4- Detect the prevalence of vancomycin resistance among S. aureus by determining MIC.
The study was held in Kafr El-Dawar General Hospital, during the period from January 2013 to October 2013. It included collection of samples from inpatients, outpatients, healthcare workers, and community individuals.
The following samples were collected:
1- Clinical samples:
- Samples were collected from abscesses, diabetic foot infections, postoperative wound infections, erysipelas, infected amputations, infected burns, an infected bedsore, and an infected gunshot wound from inpatients and outpatients.
- All clinical samples were transported to the laboratory within one hour and were inoculated on blood agar and MacConkey agar plates.
2- Nasal swabs:
- Nasal swabs were collected from inpatients, healthcare workers, and community individuals.
- All nasal samples were transported to the laboratory and were inoculated on mannitol salt agar plates.
After proper incubation, identification of isolated colonies was performed according to the standard microbiological methods. All S. aureus isolates were subjected to antibiotic susceptibility testing by disc diffusion method. The prevalence of vancomycin resistance among S. aureus was determined using MIC by agar dilution method.
The results of this study revealed that:
1- The overall mean age of clinical cases was 43 years, while the overall mean age of nasal carriers was 40 years.
2- Abscesses constituted the highest percentage of outpatient cases (41%), while diabetic foot infections constituted the highest percentage of inpatient cases (74.3 %).
3- The percentage of positive cultures was higher among patients who did not take antibiotics before (95.0%) than those who did (87.8%). However, the difference was not statistically significant.
4- There was a significant difference between inpatients and outpatients regarding the causative agents, where the predominant causative agents isolated from outpatients were S. aureus (39%), followed by CNS (18.5%), and P. aeruginosa (12.7%), while the predominant causative agents in samples collected from inpatients were CNS (54.3%), followed by P. aeruginosa (28.6%), and P. vulgaris (11.4%).
5- Nasal carriage by S. aureus had a total prevalence of only 12.5%, and healthcare workers had the highest rate (15.6%).
6- Out of the isolated S. aureus strains, 45% were MRSA.
7- S. aureus samples showed highest resistance rate against penicillin (96%), followed by oxacillin (45%), while they were most sensitive to linezolid (95%), followed by clindamycin (94%), sulfamethoxazole-trimethoprim (89%), and erythromycin and ciprofloxacin (76% for each of them).
8- Among the 200 S. aureus isolates, VRSA isolates compromised 5.5% of samples and they were all isolated from clinical samples. They constituted 13.8% of clinical samples.
9- Only one strain was found to be VISA, and it was isolated from a nasal sample of a healthcare worker.
10- All the detected VRSA and VISA strains were also resistant to methicillin.
11- VRSA isolates were most resistant to ciprofloxacin (90.9%) followed by erythromycin (81.8%), then sulfamethoxazole-trimethoprim, clindamycin and linezolid (63.6% each).
12- Five of VRSA isolates showed resistance to all the tested antibiotics.
It can be concluded from the present study that:
1- S. aureus was the most common cause of infection among outpatients, while it was not isolated from inpatients in Kafr El-Dawar General Hospital.
2- Prevalences of MRSA in both clinical and nasal samples were close (43.8% and 45.8%, respectively).
3- VISA was only detected in one strain from nasal carriage.
4- VRSA strains were only detected in clinical samples.