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Updated: Jul 23, 2025
Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Genotypically Confirmed Vancomycin-Resistant Staphylococcus aureus With vanB Gene Among Clinical Isolates in
Niranjan Nepal1, Prakriti Mahara2, Shishir Subedi3
1Central Department of Microbiology, Tribhuvan University, Kirtipur, Kathmandu, Nepal.
Purpose:
Methicillin-resistant Staphylococcus aureus, a common bacterial pathogen causes various infections. The acquisition of various antimicrobial-resistant genes in S. aureus has led to the transformation of this bacterium into a superbug. Vancomycin resistance among MRSA isolates is an emerging threat in empirical therapy of various infections. The study was hence aimed to find out the susceptibility status of S. aureus isolates toward vancomycin and detect mecA, vanA, and vanB genes among the isolates.
Methods:
A total of 1245 clinical samples from the participants attending a tertiary care hospital in Kathmandu were processed. S. aureus isolated from the samples were subjected to antibiotic susceptibility patterns using the modified Kirby-Bauer disk diffusion method. Agar dilution method was used to determine the minimum inhibitory concentration of vancomycin. The antibiotic-resistant genes such as mecA, vanA, and vanB among S. aureus isolates were screened by a conventional polymerase chain reaction.
Results:
Of 1245 samples, 80 S. aureus were identified. Out of which, 47.5% (38/80) were phenotypically confirmed MRSA isolates. mecA gene was detected in 84.2% (32/38) of MRSA isolates. 10.5% (4/38) were confirmed as vancomycin-intermediate S. aureus (VISA) by MIC determination. None of the isolates was positive for the vanA gene; however, 2 isolates were found to possess the vanB gene. The 2 isolates have vancomycin MIC breakpoints of 4 to 8 μg/mL.
Conclusion:
There might be a spreading of vancomycin resistance among S. aureus, creating serious public health problems. Therefore, measures to limit vancomycin resistance should be considered in healthcare facilities as immediately as possible.
Insights
Methicillin-resistant Staphylococcus aureus (MRSA) poses a growing threat due to vancomycin resistance. This study detected vancomycin resistance genes in S. aureus isolates, highlighting the need for immediate control measures.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Antimicrobial Resistance
Background:
- Staphylococcus aureus is a significant bacterial pathogen.
- Antimicrobial resistance, particularly in MRSA, is a growing global health concern.
- Vancomycin resistance in MRSA complicates treatment strategies.
Purpose of the Study:
- To assess vancomycin susceptibility in S. aureus isolates.
- To detect the presence of key resistance genes (mecA, vanA, vanB) in S. aureus.
- To understand the prevalence of vancomycin resistance mechanisms in clinical isolates.
Main Methods:
- Clinical samples were analyzed for S. aureus identification.
- Antibiotic susceptibility testing was performed using disk diffusion and agar dilution methods.
- Conventional polymerase chain reaction was employed to screen for mecA, vanA, and vanB genes.
Main Results:
- 80 S. aureus isolates were identified from 1245 samples.
- 47.5% of isolates were confirmed as MRSA, with mecA gene detected in 84.2%.
- Vancomycin-intermediate S. aureus (VISA) was found in 10.5% of MRSA isolates; vanA was absent, but vanB was detected in two isolates.
Conclusions:
- The presence of vanB gene indicates a potential spread of vancomycin resistance in S. aureus.
- Urgent implementation of control measures in healthcare settings is crucial to combat vancomycin resistance.
- Continued surveillance and research are necessary to address this public health challenge.
