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Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Prevalence and molecular characterization of methicillin resistance among Coagulase-negative Staphylococci at a
Puneet Bhatt1, Kundan Tandel2, Alina Singh3
1Graded Specialist (Microbiology), Command Hospital (Southern Command), Pune 411040, India.
Background:
Methicillin-resistant Coagulase-negative Staphylococci (MR-CoNS) have emerged as an important cause of nosocomial infections especially in patients with prosthetic devices and implants. This study was conducted with an aim to determine the prevalence of methicillin resistance among CoNS isolates at a tertiary care center by both phenotypic and genotypic methods.
Methods:
This cross sectional study was carried out from September 2011 to February 2014 in which 150 non-repetitive clinical isolates of CoNS were identified at the species level by conventional phenotypic methods. Cefoxitin disk (30 μg) diffusion testing was used to determine methicillin resistance and confirmed by detection of mecA gene by polymerase chain reaction (PCR).
Results:
Out of 150 CoNS isolates, 51 were methicillin resistant by cefoxitin disk diffusion method. Out of these 51 isolates, mecA gene was detected only in 45 isolates. Moreover, mecA gene was also detected in 4 isolates, which were cefoxitin sensitive. Thus, the prevalence of methicillin resistance among CoNS was found to be 32.7% by PCR.
Conclusion:
The prevalence of methicillin resistance among Coagulase-negative Staphylococci (CoNS) was 32.7% by PCR detection of mecA gene. The sensitivity and specificity of cefoxitin disk diffusion method against mecA gene detection by PCR were found to be more than 90%. It can be concluded from this study that cefoxitin disk diffusion test can be used as a useful screening method to detect methicillin resistance among CoNS isolates. However, detection of mecA gene by PCR remains a more accurate method of detecting methicillin resistance among CoNS.
Insights
Methicillin resistance in Coagulase-negative Staphylococci (CoNS) affects 32.7% of isolates. The cefoxitin disk diffusion test is a reliable screening method, with PCR confirming methicillin resistance accurately.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Diagnostics
Background:
- Coagulase-negative Staphylococci (CoNS) are a significant cause of hospital-acquired infections, particularly in patients with medical implants.
- Methicillin resistance in CoNS (MR-CoNS) poses a growing clinical challenge.
- Accurate detection of MR-CoNS is crucial for effective patient management.
Purpose of the Study:
- To determine the prevalence of methicillin resistance among CoNS isolates at a tertiary care center.
- To compare phenotypic (cefoxitin disk diffusion) and genotypic (PCR for mecA gene) methods for detecting methicillin resistance in CoNS.
Main Methods:
- A cross-sectional study involving 150 clinical CoNS isolates identified by conventional methods.
- Methicillin resistance was assessed using cefoxitin disk diffusion (30 μg).
- Confirmation of methicillin resistance was performed by detecting the mecA gene via polymerase chain reaction (PCR).
Main Results:
- Out of 150 CoNS isolates, 51 (34%) were resistant to methicillin by cefoxitin disk diffusion.
- The mecA gene was detected in 45 of the 51 cefoxitin-resistant isolates.
- PCR detected methicillin resistance in 32.7% of all CoNS isolates, with mecA gene also found in 4 cefoxitin-susceptible isolates.
Conclusions:
- The prevalence of methicillin resistance among CoNS isolates was 32.7%, confirmed by PCR detection of the mecA gene.
- The cefoxitin disk diffusion method demonstrated high sensitivity and specificity (>90%) compared to PCR.
- Cefoxitin disk diffusion serves as a valuable screening tool, but PCR confirmation of the mecA gene remains the gold standard for accurate detection of methicillin resistance in CoNS.
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