Priya, S (2014) Genotypic and Phenotypic characterization of Methicillin Resistant Staphylococcus aureus from ocular isolates and its clinical correlation. Masters thesis, Aravind Eye Hospital and Post Graduate Institute of Ophthalmology, Madurai.
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Abstract
INTRODUCTION: MRSA, a versatile and dangerous pathogen, first identified in the 1960s, was traditionally associated with healthcare facilities. Now it is also a dominant pathogen in community associated infections. It has a high rate of morbidity and mortality because of its multiple drug resistance resulting in limited treatment options and its increasing prevalence. Colonizing staph can cause serious conditions such as abscesses, osteomyelitis, staphylococcal pneumonia, septicemia, toxic shock syndrome and endocarditis. In the eye, it can cause preseptal and orbital cellulitis, lid abscess, conjunctivitis, corneal ulcers, endophthalmitis and blebitis. MRSA can be either hospital acquired (HA) or community acquired (CA). The mecA gene in these strains encodes the altered protein PBP2A which shows resistance to methicillin. This gene resides on the Staphylococcal cassette chromosome (SCCmec). Differences in virulence factors between HA-MRSA and CA-MRSA organisms may allow the community strains to spread more easily compared with the traditional hospital-based MRSA strains. AIM OF THE STUDY: To analyze clinical features, prevalence, molecular typing and antibiotic susceptibility of MRSA in ocular infections. MATERIALS & METHODS: MRSA isolates were collected over a period of one year from patients presenting with various ocular infections. Antibiotic susceptibility was done by disc diffusion method. Staphylococcal cassette chromosome (SCC) mec typing was done by PCR. The phenotypic and genotypic charecteristics were correlated with the clinical manifestations. RESULTS: Of 136 staphylococcus aureus isolated, 34(25.3%) were MRSA. SCC mec typing was done for all 34 strains. 30 (88.2%) belonged to community acquired strains (type IV and V), 2 were hospital acquired strains and 2 were not typeable. Orbital infections were caused by both types IV and V while corneal and scleral infections were mainly caused by type V. All were sensitive to vancomycin and chloramphenicol, 70% were sensitive to Cefazolin, 28% to gatifloxacin, ofloxacin and levofloxacin, 17% to gentamycin, 14% to tobramycin and 6% to Moxifloxacin.None of the isolates were sensitive to ciprofloxacin. CONCLUSION: Ocular infections are predominantly caused by Community acquired strains. They are resistant to commonly used fluroquinolones. Vancomycin and chloramphenicol remain the drugs of choice. Appropriate surgical intervention adds to better prognosis.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | Genotypic and Phenotypic characterization ; Methicillin Resistant Staphylococcus aureus ; ocular isolates ; clinical correlation. |
| Subjects: | MEDICAL > Ophthalmology |
| Depositing User: | Devi S |
| Date Deposited: | 24 Jun 2018 02:30 |
| Last Modified: | 24 Jun 2018 02:30 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/8577 |
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