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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
A STRATEGY FOR RAPID IDENTIFICATION OF METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS NASAL CARRIER STATUS
P K Menon1, A B Desai2, A Nagendra3
1Reader, Medical Cadet, Armed Forces Medical College, Pune - 411 040.
Abstract:
Methicillin Resistant Staphylococcus aureus (MRSA) is a multi drug resistant organism responsible for severe outbreaks of life threatening infections in hospitals which are difficult to treat They are spread by nasal carriage among the hospitalised patients, staff and visitors. Mannitol cloxacillin salt agar (MCSA) is a single tube method to identify MRSA. However, tubes showing growth and change in colour on biochemical characterisation often do not prove to be MRSA. In this study we have combined two strategies for the rapid identification and isolation of MRSA by culture in MCSA and multiplex PCR for mecA and femB genes. Anterior nasal swabs obtained from nursing staff and patients admitted to a large referral hospital, were inoculated into MCSA. Of the 100 tubes inoculated, 8 tubes showed change in colour and growth. On conventional testing 4 were MRSA, 3 were methicillin sensitive S aureus (MSSA) and 1 was Methicillin Sensitive Coagulase Negative S aureus (MSCNS). Genotyping by multiplex PCR revealed 5 MRSA, 2 MSSA and 1 MRCNS. The Multiplex PCR technique to rapidly identify presence of mecA and femB genes showed presence of both mecA and femB bands in all MRSA. The methicillin sensitive organisms showed absence of mecA gene while coagulase negative organisms showed absence of the fern B gene. Combining MSCA with multiplex PCR for mec A and fem B genes made the test both rapid and specific. Use of this strategy would enable rapid screening of nasal carriers and early implementation of hospital infection control measures.
Insights
Rapidly identify Methicillin-Resistant Staphylococcus aureus (MRSA) using Mannitol Cloxacillin Salt Agar (MCSA) combined with multiplex PCR. This method accurately detects MRSA nasal carriage, enabling faster infection control in hospitals.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Molecular Diagnostics
Background:
- Methicillin-Resistant Staphylococcus aureus (MRSA) poses a significant threat due to its multi-drug resistance and role in severe hospital-acquired infections.
- Nasal carriage of MRSA among patients, staff, and visitors facilitates its spread within healthcare settings.
- Current identification methods, like Mannitol Cloxacillin Salt Agar (MCSA), can lack specificity, leading to inaccurate MRSA diagnoses.
Purpose of the Study:
- To develop and evaluate a rapid and specific method for identifying MRSA nasal carriage.
- To combine culture-based identification with molecular detection for improved accuracy.
- To facilitate early implementation of infection control measures by enabling rapid screening.
Main Methods:
- Anterior nasal swabs were collected from hospital patients and nursing staff.
- Samples were cultured on Mannitol Cloxacillin Salt Agar (MCSA).
- Multiplex PCR targeting the mecA and femB genes was performed on isolates showing growth and color change.
Main Results:
- Of 100 inoculated tubes, 8 showed growth and color change. Conventional testing identified 4 MRSA, 3 MSSA, and 1 MSCNS.
- Multiplex PCR genotyping revealed 5 MRSA, 2 MSSA, and 1 MRCNS.
- MRSA isolates consistently showed both mecA and femB genes, while methicillin-sensitive strains lacked mecA and coagulase-negative strains lacked femB.
Conclusions:
- Combining MCSA with multiplex PCR for mecA and femB genes provides a rapid and specific method for MRSA identification.
- This strategy allows for efficient screening of nasal carriers.
- Early identification of MRSA carriers can lead to prompt implementation of hospital infection control protocols.
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