الفهرس 
The Staphylococcus genusOnly 14 pages are availabe for public view
 |  | from | 133 |  |  |
| | | from | 133 | | |
Abstract
Summary
The genus Staphylococcus is composed of Gram-positive bacteria with
diameters of 0.5-1.5 μm, characterized by individual cocci that divide in more
than one plane to form grape-like clusters.
Resistance to methicillin was uncommon until the late 1960s, when a
multidrug-resistant MRSA emerged in Europe.
Until the 1990s, MRSA was exclusively a hospital- associated pathogen.
Then, cases of MRSA community infections were documented in individuals in
the U.S. without any history of hospitalization. These first cases were fatal, but
most CA- MRSA infections present as moderately severe infections of the skin
and soft tissues.
The present study was conducted on 200 out patients from EL- Fayoum
General Hospital (El- Fayoum- Egypt) during the period from January 2016 to
December 2016. selected Patients were of all age groups, both sexes, and had
soft tissue infection.
Swabs were collected from the infected soft tissue (200 cases) using
sterile disposable cotton swabs (Eipico Co. Egypt).
- Microbiological identification of S. aureus done using routine
microbiological methods
- primary Identification of methicillin resistant S. aureus by cefoxitin disc
diffusion method and culture on ORSAB (oxacillin resistance screening agar
base) medium
- Identification of CA-MRSA by polymerase chain reaction
- Detection of MRSA mecA, Pvl and SCCmec genes
Summary
3
the patients age ranged from 1 year to 78 years. Staphylococci were 126
(62%) of the studied cases; one third of them were MRSA and the most common
form of infection by MRSA were abscesses.
resistance rates to antibiotics were the highest with penicillin G (100%),
ampicillin (100%), amoxicillin- clavulanic acid (100%), Cefotaxime (100%,
Cefepime (100%) while the lowest resistance were with Levofloxacin (2.4%),
Clarithromycin (12.2%), Ciprofloxacin (12.2),
Sulphamethoxazole/Trimethoprim (12.2%), Imipenem (14.6%),
Chloramphenicol (14.6%) and Linezolid (24.4%).
None of the isolates were resistant to vancomycin by MIC determination
(92.7% sensitive and 7.3% vancomycin intermediate resistance S. aureus
(VISA)).
Beta-lactam resistance is attributed mostly to mutations in the mecA gene,
but other genetic elements may also be considered for the explanation of the
mechanism of resistance we found mecA gene were present in 92.68% of the
cases.
SCCmec types: I, II were negative in all cases, type III positive in 7
samples while types IVa, IVb, IVc, IVd were present in 1, 0, 1, 5 cases
respectively. Type V found in 5 cases
Panton-Valentine leukocidin (PVL) is a potent cytotoxin and an important
virulence factor of S. aureus. Pvl -positive S. aureus, as a rapidly emerging
worldwide phenomenon and we found Pvl gene in 100% of the studied cases.
Some cases of CA- MRSA had sec enterotoxin gene which can cause
staphylococcal food poisoning so standard precaution should be applied to
prevent infection specially hand hygiene.