Detection and Characterisation of Heteroresistant Vancomycin Intermediate Staphylococcus aureus (hVISA) using Phenotypic and Genotypic Methods
Journal Title: Journal of Clinical and Diagnostic Research - Year 2019, Vol 13, Issue 5
Abstract
ABSTRACT Introduction: Vancomycin remains the drug of choice to treat infections caused by Methicillin Resistant Staphylococcus aureus (MRSA). Frequent therapeutic failures arise due to the emergence of strains with reduced susceptibility to vancomycin and difficulty in detecting these isolates. Therefore, improvements in screening and confirmatory tests to detect these isolates are required. Aim: To detect heteroresistant Vancomycin Intermediate Staphylococcus aureus (hVISA) isolates among Methicillin Resistant Staphylococcus aureus (MRSA) and Methicillin Sensitive Staphylococcus aureus (MSSA) obtained from various clinical samples and to study the phenotypic and genotypic charecteristics of these strains. Materials and Methods: This study was carried out in the Department of Microbiology, Chettinad Hospital and Research Institute, Kelambakkam, Chennai, Tamil Nadu, India. A total of 468 non-duplicate S.aureus strains obtained from various clinical samples during a period of two years from September 2014 to November 2016 were included in the study. MRSA isolates and hVISA/VISA isolates were detected by screening and confirmatory methods (MRSA screen by cefoxitin disc, hVISA/VISA screen by brain heart infusion agar with 6 μg vancomycin and hVISA/VISA confirmation by PAP-AUC method). Agr polymorphism in hVISA/VISA was analysed by duplex PCR. Accessory gene regulator (Agr) dysfunction in these strains was studied by their colony spreading property in soft agar and autolytic property by Triton X-100 induced lysis. The results were analysed using IBM SPSS (version 21.0) software. Results: Out of 468 S.aureus strains, 114 (24%) strains were detected as MRSA and 33 (7.0%) were hVISA/VISA strains. Among MRSA detected, 11 (9.5%) strains were confirmed as hVISA/VISA. All hVISA/VISA isolates showed reduction in autolytic activity. Colony spreading property was appreciated in 13 (39%) of these isolates. Out of the 33 hVISA/VISA strains, majority belonged to agr I, III and II and the least number of isolates belonged to agr IV. Conclusion: It was concluded that hVISA/VISA strains have diverse virulence properties and are detected in both MRSA and MSSA strains. Therefore, surveillance of these strains among S.aureus isolates having vancomycin MIC’s ≤1.5 μg/mL in laboratory settings is needed.
Authors and Affiliations
Alice Peace Selvabai, Shameem Banu Abdul Sattar, Perumal Jayaraman, Priyadarshini Shanmugam
Keywords
Related Articles
- EP ID EP586061
- DOI 10.7860/JCDR/2019/41127.12868
- Views 129
- Downloads 0
Effectiveness of Indian Diabetes Risk Score as a Screening Tool for Non-alcoholic Fatty Liver Disease: A Study from Anand, Gujarat, India
ABSTRACT Introduction: Non-alcoholic fatty liver disease (NAFLD) is widely prevalent in the Gujarati population and also shares risk factors with other Non-communicable diseases (NCDs) such as diabetes, obesity, and meta...
Ebola Vaccine: How Far are we?
Ebola viruses have been identified as an emerging threat as it causes severe haemorrhagic fever in human with mortality rates ranging from 50 to 90%. In addition to being a global health concern, the virus also is consid...
The Status of Knowledge Related to the Emergency Management of Avulsed Tooth amongst the Medical Practitioners of Nagpur, Central India
Introduction: Tooth avulsion is a frequently reported traumatic injury amongst young children and whenever it occurs, the parents or teachers of those children often seek the help of Medical Practitioners to provide the...
To Operate or not to Operate the Mid-Shaft Fractures of the Clavicle: A Comparative Study of Functional Outcomes of the Two Methods of Management
Introduction: Fractures of the clavicle are some of the most common fractures which are seen in the adult population. Midshaft fractures of the clavicle are considered the most common form of clavicle fractures and about...
Bilateral Conjunctival Rhinosporidiosis in a Paediatric Patient
Letter to Editor