scholarly journals Evaluation of various phenotypic methods with genotypic screening for detection of methicillin-resistant Staphylococcus aureus

2020 ◽  
Vol 13 (6) ◽  
pp. 225-233
Author(s):  
Archana Loganathan ◽  
Prasanth Manohar ◽  
Kandasamy Eniyan ◽  
Rama Jayaraj ◽  
Ramesh Nachimuthu
Keyword(s):  
Staphylococcus Aureus ◽  
Tamil Nadu ◽  
Inhibitory Concentration ◽  
Pcr Amplification ◽  
Clinical Isolates ◽  
Disk Diffusion ◽  
Methicillin Resistant ◽  
Polymerase Chain ◽  
Phenotypic Methods ◽  
Specificity Pattern

AbstractBackgroundStaphylococcus aureus is one of the common opportunistic gram-positive pathogens which are often associated with nosocomial infections. Detection of methicillin-resistant S. aureus (MRSA) has become complicated due to the complex phenotypic and genomic pattern.ObjectiveTo evaluate the sensitivity and specificity pattern of various phenotypic methods used in screening mec genes harboring MRSA.MethodsClinical isolates of S. aureus were collected from diagnostic centers in Tamil Nadu. Phenotypic identification methods such as Minimal Inhibitory Concentration for oxacillin, oxacillin screen agar (OSA), oxacillin disk diffusion, and cefoxitin disk diffusion (CFD) tests were compared. The clinical isolates were classified into MRSA and methicillin-susceptible S. aureus (MSSA) based on the polymerase chain reaction (PCR) amplification of the mecA gene.ResultOut of 50 S. aureus, 21 were found to be MRSA based on the presence of the mecA gene. All 21 mecA-positive isolates were found to be resistant through minimum inhibitory concentration (MIC) and CFD test, having a sensitivity of 100% and specificity of 52% and 62%, respectively. OSA and oxacillin disk tests were found to have a sensitivity of 86% and specificity of 48% and 52%, respectively.ConclusionThe combination of two phenotypic methods, CFD and oxacillin MIC, can be used for the detection of MRSA in clinical laboratories.

scholarly journals Vancomycin, linezolid and daptomycin susceptibility pattern among clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) from Sub- Himalyan Center

2018 ◽  
Vol 10 (02) ◽  
pp. 145-148 ◽  
Author(s):  
Afzal Husain ◽  
Vinita Rawat ◽  
Mukesh Kumar ◽  
Pankaj Kumar Verma ◽  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Inhibitory Concentration ◽  
Geometric Mean ◽  
Clinical Isolates ◽  
Susceptibility Pattern ◽  
Methicillin Resistant ◽  
Therapeutic Advantage ◽  
Drug Of Choice ◽  
Alternative Agent

ABSTRACT INTRODUCTION: The efficacy of vancomycin, drug of choice for methicillin-resistant Staphylococcus aureus (MRSA), has become questionable due to the emergence of MRSA isolates with reduced susceptibility. The present study was conducted to determine the vancomycin, linezolid, and daptomycin susceptibility pattern in clinical isolates of MRSA and to observe minimum inhibitory concentration (MIC) creep over 2 years if any. MATERIALS AND METHODS: MIC of vancomycin, linezolid, and daptomycin were determined by E-test in 198 MRSA isolates and their MIC 50, MIC 90, and geometric mean MIC were calculated. RESULTS: While all isolates were sensitive to vancomycin, linezolid, and daptomycin, MIC 90 of vancomycin increased from 1.5 µg/ml in 2015 to 2 µg/ml in 2016. The percentage of isolates with vancomycin MIC >2 µg/ml doubled in 2016 (12.9%) as compared to 2015 (6.1%). MIC 90 for linezolid remained steady as 3 µg/ml, but geometric mean MIC increased from 2.20 µg/ml in 2015 to 2.29 µg/ml in 2016, and more than 40% isolates showed MIC 3 µg/ml. MIC 90 and geometric mean MIC of daptomycin decreased from 0.75 µg/ml to 0.5 µg/ml and 0.50 µg/ml to 0.36 µg/ml in 2015 and 2016, respectively. CONCLUSION: MIC creep was observed with vancomycin. Although linezolid MIC was within the susceptible zone, more than 40% strains showing MIC 3 µg/ml may herald the future development of either resistant or heteroresistant. Daptomycin showed good sensitivity against MRSA isolates. Therefore, it could be considered as an alternative agent for the treatment of infections caused by MRSA. However, it should be reserved where this class has a clear therapeutic advantage over other anti-MRSA drugs.

scholarly journals Reduced Triclosan Susceptibility in Methicillin-Resistant Staphylococcus epidermidis

2004 ◽  
Vol 48 (4) ◽  
pp. 1397-1399 ◽  
Author(s):  
Molly B. Schmid ◽  
Nachum Kaplan
Keyword(s):  
Staphylococcus Aureus ◽  
Minimal Inhibitory Concentration ◽  
Staphylococcus Epidermidis ◽  
Inhibitory Concentration ◽  
Clinical Isolates ◽  
Methicillin Resistant

ABSTRACT Triclosan MIC determination showed that recent Staphylococcus aureus clinical isolates (n = 100) were highly susceptible to triclosan, with a 50% minimal inhibitory concentration (MIC50) of 0.12 μg/ml and a MIC90 of 0.25 μg/ml. Staphylococcus epidermidis isolates (n = 96) were less susceptible, with a MIC50 of 0.12 μg/ml and a MIC90 of 8 μg/ml. Decreased susceptibility to triclosan was more prevalent among methicillin-resistant S. epidermidis than among methicillin-sensitive S. epidermidis isolates.

scholarly journals Levonadifloxacin: A Novel Approved Drug Exhibiting Potent In vitro Activity against Gram Positive Bacterial Isolates from Patients Admitted in Intensive Care Units

2021 ◽  
Author(s):  
Tasneem Siddiqui ◽  
Rafat Shamim ◽  
Sangram Singh Patel ◽  
Chinmoy Sahu
Keyword(s):  
Staphylococcus Aureus ◽  
Intensive Care ◽  
Intensive Care Units ◽  
Clinical Isolates ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Gram Positive ◽  
Disk Diffusion Method ◽  
Methicillin Resistant

Introduction: Levonadifloxacin is a novel antibiotic belonging to the benzoquinolizine subclass of fluoroquinolone with potent activity against Methicillin Resistant Staphylococcus aureus (MRSA) and Quinolone Resistant Staphylococcus aureus (QRSA). Both intravenous levonadifloxacin and its oral formulation have recently been approved in India for the treatment of acute bacterial skin related infections. Aim: To assess the activity of levonadifloxacin against gram positive clinical isolates collected from Intensive Care Units (ICUs) using the disk-diffusion method. Materials and Methods: The present descriptive study where non duplicate isolates of Staphylococcus aureus (S. aureus) and other gram positive isolates from various clinical samples from all Intensive Care Units (ICUs) were collected from June to December 2020 and subjected to levonadifloxacin susceptibility testing (disk diffusion method) as per the Clinical and Laboratory Standards Institute (CLSI) guidelines, 2020. Data analysis was performed using Statistical Package for the Social Sciences (SPSS) software, version 25.0. Results: A total of 142 gram positive clinical isolates collected from all ICUs of the hospital were analysed. These isolates included coagulase negative S. aureus 109 (76.8%), S. aureus 21 (14.8%) and Enterococcus faecalis 12 (8.4%). All the gram positive isolates of the study were susceptible to levonadifloxacin as per the prespecified interpretive criteria identified based on population pharmacokinetic model and Monte Carlo simulation enabled probability of pharmacodynamic target attainment analysis. Conclusion: Results of this in vitro study shows good activity of levonadifloxacin against gram positive isolates including difficult to-treat methicillin resistant staphylococcal isolates collected from ICU patients.

scholarly journals Detection of Methicillin Resistance in Staphylococcus Aureus by Polymerase Chain Reaction and Conventional Methods: A Comparative Study

2012 ◽  
Vol 4 (02) ◽  
pp. 083-088 ◽  
Author(s):  
Manju M Pillai ◽  
Ragunathan Latha ◽  
Gautam Sarkar
Keyword(s):  
Staphylococcus Aureus ◽  
Polymerase Chain Reaction ◽  
Methicillin Resistance ◽  
Meca Gene ◽  
Disk Diffusion ◽  
Chain Reaction ◽  
Mannitol Salt Agar ◽  
Polymerase Chain ◽  
Conventional Methods ◽  
Phenotypic Methods

ABSTRACT Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen worldwide, which has emerged over the past 30 years as a leading cause of both nosocomial and community-acquired infections. Accurate and rapid identification of MRSA in clinical specimens is essential for timely decision on effective antimicrobial chemotherapy. Aim: The present study was conducted to compare two conventional phenotypic methods, oxacillin disk diffusion (ODD) Aim: The present study was conducted to compare two conventional phenotypic methods, oxacillin disk diffusion (ODD) method and mannitol salt agar (MSA) with oxacillin, with polymerase chain reaction (PCR) for mecA gene (as standard). Materials and Methods: A total of 165 consecutive clinical isolates of S. aureus received at the Department of Microbiology in our tertiary care teaching hospital were included in the study. All the isolates were subjected to ODD (1 μg) method, culture in MSA with oxacillin, and PCR for mecA gene. Results: The sensitivity and specificity of ODD test were found to be 93.5% (86.4-97.3%) and 83.5% (79.2-85.8%), respectively, and that of MSA with oxacillin were found to be 87.1% (79.5-92.3%) and 89.3% (84.8-92.5%), respectively. The time taken for diagnosing MRSA by conventional methods is 48-72 h, which is more as compared to PCR which takes 18-24 h. Conclusion: This study recommends advocating PCR for mecA gene on a regular basis for detecting methicillin resistance in S. aureus isolates isolated from sterile body fluids or from special units such as intensive care units.

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