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دراسة جزيئية عن جين المقاومة mecA في بكتريا العنقودية الذهبية المقاومة للمشيسلين والمعزولة من بعض مستشفيات بغداد == Molecular Study For Detection of Meca Gene In Methicillin - Resistant Staphylococcus Aureus Isolated From Some Hospital In Baghdad City
Author name:
لمى ياسين موسى
Supervisor name:
محمد ابراهيم نادر
General topic:
Biology
Specific topic:
Biotechnologies
Degree:
Master
University:
University of Baghdad - Institute Of Genetic Engineering And Biotechnology - Department Of Biotechnology
Language:
English
University location:
Baghdad
First pages:
24T2943 - p.pdf
Abstract:
Two hundred and thirty clinical specimens were collected from two different hospitals in Baghdad during the period (December 2012 to April 2013). These specimens were collected from visitors, hospitalized patients and the health care workers in these hospitals. The specimens included nasal swab, wound swab, burn swab, abscess and pus, sputum, ear swab, urine and blood culture diagnostic results show that 150 out of the (230) specimens gave positive bacterial cultures and (100) isolates are characterized as Staphylococcus aureus depending on the cultural and biochemical examinations.the coagulase test was performed and the results showed that from total 150 isolates of Staphylococci, 100 isolates (61%) were coagulase - positive (COPS), while only 50 isolates (39%) were coagulase negative (CONS). In addition, the distribution of methicillin resistance among Staphylococcus spp. was investigated.The use of the antibiotic susceptibility profile for these isolates was examined against methicillin resistance. Using disk diffusion method revealed that (13) isolates were proved to be methicillin resistant Staphylococcus aureus (MRSA), While (87) isolates of S. aureus showed sensitivity to methicillin (MSSA) and there was no intermediate resistance among these isolates.The ability of MRSA isolates to produce some virulence factors were investigated and the results showed that MRSA isolates produce many enzymes and toxins that contributed in their virulence such as protease, urease, dnase and gelatinase, and also produce a beta types of haemolysins.The ability to produce slime layer by MRSA isolates was also investigated and the results showed that all isolates of MRSA were produced slime layer when theytested by Congo red agar method and the results showed that all of MRSA isolates produced strong slime layer.One of the aims of this study was to adopted a accurate diagnostic method to detect S.aureus by its genetic material contents through extracting of DNA and gel electrophoresis of the PCR product for the specific gene.Detection of methicilline - resistance gene represented by A confirmatory test was carried out for the selected isolates using Polymerase chain reaction (PCR) technique for further characterization up to the species level by the amplification of (mecA) gene.This is Staphylococcus aureus specific gene that encodes the extra Penicillin Binding Protein, which is unique to methicillin - resistant staphylococci. All the (13) positive isolates by disk diffusion test are found to be positive for the presence of (mecA) gene as their agarose gel revealed the presence of DNA band of mecA gene with a molecular size about (200 bp.).Results of the detecting (femB) gene showed that it was positive in all of MRSA isolates as they appear to have a band with a molecular size of about (651 bp). The genetic determinants of methicillin resistance mecA and femB genes were amplified using multiplex PCR technique in order to identify methicillin resistant (mecA+) and susceptible (lacking mecA) staphylococci and to differentiate S. aureus (femB+) from coagulase negative staphylococci (lacking femB). All of the S. aureus isolates (100%) were found to harbor femA gene, it is species specific marker for S. aureus.
