Evaluation of Genotypic and Phenotypic Methods for Detection of Methicillin Resistant Staphylococcus aureus in a Tertiary Care Hospital of Eastern Odisha

Abstract

Introduction: Methicillin resistant Staphylococcus aureus has emerged as an important pathogen in nosocomial and community acquired infections. Accurate and rapid identification of MRSA in clinical specimens is essential for timely decision of effective antimicrobial chemotherapy. Aim:The present study was conducted to compare efficacy of four conventional phenotypic methods, with mec-A based polymerase chain reaction (PCR) for MRSA identification. materials and methods: Methicillin resistance was determined in 200 S.aureus isolates by oxacillin disc diffusion, cefoxitin disc diffusion, Oxacillin Resistance Screening Agar and E-test. The results were compared with mec-A based PCR.Results: Among 200 S.aureus isolates 62 (31%) were positive for mec-A gene by PCR. Cefoxitin disc diffusion, Oxacillin Resistance Screening Agar and E-test showed 100% specificity. Oxacillin disc diffusion had lowest sensitivity (82.5%) and specificity (98.5%) among all. The conventional methods take more time than PCR for diagnosing MRSA. Linezolid, Vancomycin & Dalfopristin were the highly sensitive drugs against MRSA isolates. Conclusion:Cefoxitin disc diffusion, is rapid, simple and cheaper, hence can be used routinely as an alternative to PCR for detection of MRSA in resource constraint laboratories.

Resistance pattern of methicillin resistant Staphylococcus aureus among nasal isolates of HIV infected patients in a tertiary care hospital

“…Our finding was also in consideration with various other author's findings. 21,22 Rural population was at more risk for nasal carriage among HIV seropositive patients (statistically non significant) in the present study. Females (20.97%) account for more (statistically non significant) nasal carriage MRSA as compared to males (14.71%).…”

Evaluation of the Role Of bla Genes in Beta Lactam and Methicillin Resistant Staphylococcus aureus

“…Ostojić & Hukić (2015) demonstrated a correlation between phenotypic and genotypic characteristics. Their results revealed that all MrSA isolates were mecA + , while Panda et al (2016) stated that using conventional methods for detection of MrSA is more significant than detection with PCR. In the present study, 15.6% (n= 8) isolates showed low level of resistance to oxacillin (1 or 2μg/ml) were found to harbor mecA gene, while four isolates that were resistant to ≥4μg/ml oxacillin lacked mecA gene.…”

Molecular Detection of Methicillin-Resistant Staphylococcus aureus by Non-Protein Coding RNA-Mediated Monoplex Polymerase Chain Reaction

“…Hence, we developed the npcRNA based detection using Sau-02 gene. Most of the detection studies carried out qualitatively to show the presence or absence of MRSA [ 36 , 39 , 40 ]. However, in our study we showed the detection level of genomic DNA equivalent to genome copies and whole cell MRSA as ~10 and 2 respectively.…”