Molecular analysis of chloramphenicol resistance in staphylococci
2
Issued Date
2002
Copyright Date
2002
Resource Type
Language
eng
File Type
application/pdf
No. of Pages/File Size
xii, 80 leaves : ill.
ISBN
9740418686
Access Rights
open access
Rights
ผลงานนี้เป็นลิขสิทธิ์ของมหาวิทยาลัยมหิดล ขอสงวนไว้สำหรับเพื่อการศึกษาเท่านั้น ต้องอ้างอิงแหล่งที่มา ห้ามดัดแปลงเนื้อหา และห้ามนำไปใช้เพื่อการค้า
Rights Holder(s)
Mahidol University
Bibliographic Citation
Thesis (M.Sc. (Immunology))--Mahidol University, 2002
Suggested Citation
Ubonwan Jotekratok Molecular analysis of chloramphenicol resistance in staphylococci. Thesis (M.Sc. (Immunology))--Mahidol University, 2002. Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/104285
Title
Molecular analysis of chloramphenicol resistance in staphylococci
Alternative Title(s)
การศึกษาในระดับโมเลกุลของแบคทีเรียกลุ่ม staphylococci ต่อการดื้อยาคลอแรมเฟนีคอล
Author(s)
Abstract
Staphylococci are among the most important bacterial pathogens. S. aureus is a major cause of both nosocomial and community-acquired infections. Coagulase-negative staphylococci (CNS) are important nosocomial pathogens causing infections of prosthetic implants and devices. Antimicrobial resistance is an important problem for the therapy of staphylococcal infections. Staphylococci, especially methicillin-resistant staphylococci (MRS) are resistant to most antimicrobial agents, including chloramphenicol. Chloramphenicol is a broad-spectrum antibiotic that causes a bacteriostatic effect by binding to 50s subunit of ribosomal RNA and it inhibits the elongation of protein synthesis. The most important mechanism of chloramphenicol resistance in staphylococci involved chloramphenicol acetyltransferase (CAT), which acetylated the 3-hydroxy group of chloramphenicol, so the acetylated chloramphenicol cannot bind to the target site. The CAT enzymes are encoded by cat genes on plasmids. The staphylococcal cat-encoded plasmids can be divided into 3 groups, based on sequence homology: pC221, pC223 and pC194 groups. In this study, A total of 149 clinical staphylococcal isolates, which were divided into 4 groups based on methicillin susceptibility, including methicillin-resistant S. aureus (MRSA), methicillin-sensitive S. aureus (MSSA), methicillin-resistant coagulase-negative staphylococci (MRCNS) and methicillin-sensitive coagulase-negative staphylococci (MSCNS) were studied. All of the 149 staphylococcal isolates exhibited the chloramphenicol minimum inhibitory concentration (MIC), between 16-128 mg/ml. These staphylococcal isolates were resistant to chloramphenicol, according to the recommendation of NCCLS. The cat genes of all 149 staphylococcal isolates were detected by multiplex PCR. The pC221-related cat gene was observed in 2.9%, 80%, 70% and 25% of MRSA, MRCNS, MSSA and MSCNS, respectively, whereas pC223-related cat gene was found in 20%, 30% and 75% of MRCNS, MSSA and MSCNS, respectively. Surprisingly, the pC223-related cat gene was not found in MRSA, whereas the pC194-related cat gene was solely observed in MRSA, with a frequency of 95.6%. However, there is one isolate of MRSA (MRSA505) in which the cat gene could not be detected by PCR. The unique distribution of cat-specific plasmid suggests a pattern of transmission of genetic material between specific groups of bacteria that may relate to the drug resistance in some bacterial isolates. The location of the cat gene of 20 random isolates of each cat-encoded plasmid groups were studied by Southern blot hybridization. The cat genes of each cat-encoded plasmid group were observed only on plasmids. This indicated the potential of the staphylococcal cat gene in the spread of itself among staphylococcal isolates via mechanisms of gene transfer.
Description
Immunology (Mahidol University 2002)
Degree Name
Master of Science
Degree Level
Master's degree
Degree Department
Faculty of Medicine Siriraj Hospital
Degree Discipline
Immunology
Degree Grantor(s)
Mahidol University