Risk factors associated with MRSA

Sonal Gupta,Vinita Dogra,Aradhana Bhargava,Archana Thankur,Manisha Jain,Poonam S Loomba,Bibhabati Mishra

doi:10.4102/sajid.v33i3.9

Abstract

Background: Methicillin-resistant Staphylococcus aureus (MRSA) infection is associated with increased morbidity and mortality compared with infections caused by methicillin-sensitive Staphylococcus aureus (MSSA). Treatment of MRSA infection is complicated by the fact that these organisms are resistant to multiple antimicrobial agents, so treatment options are limited. The aim of the present study is determine risk factors association with MRSA as compared with MSSA and to compare the minimum inhibitory concentrations (MICs) of vancomycin, teicoplanin, linezolid and erythromycin to MRSA and MSSA.Methods: A nine-month prospective study was carried out. Staphylococcus aureus strains with clinical correlation, isolated from hospitalised patients, were included in the study. MIC of vancomycin, teicoplanin, linezolid and erythromycin was determined by E-test (HIMEDIA). Risk factors such as immunosuppression, previous hospitalisation, surgical procedure done, invasive devices and antibiotic therapy were determined by a pre-set protocol.Results: A total of 62 S. aureus strains were included in the study. Some 40% of S. aureus strains were methicillin resistant. The risk factors, invasive devices, previous hospitalisation and comorbid illness were found to be significantly associated with MRSA. Borderline significant association was observed with immunosuppression and antibiotic therapy. Erythromycin resistance was observed in 56% of MRSA, while no resistance was observed in MSSA. Teicoplanin MIC50 values and mean MIC were found to be lowest in vitro among vancomycin and linezolid against both MRSA and MSSA. The efficacy of teicoplanin, in terms of clinical and microbiological cure, has not been proven to be superior to vancomycin, but it has a better toxicity profile and has demonstrated a reduced risk of adverse events. Conclusions: Minimising risk factors and attention to alternative antibiotics and infection control practices may ease the problem of management of infections with MRSA.

Highlights

The overall Methicillin-resistant Staphylococcus aureus (MRSA) prevalence in India has been reported as 42% in 2008 and 40% in 2009
Erythromycin resistance was observed in 56% of MRSA, while no resistance was observed in methicillin-susceptible Staphylococcus aureus (MSSA)
The present study showed a mean minimum inhibitory concentrations (MICs) value for MRSA against vancomycin to be 0.81 μg/ml, which is higher than the 0.46 μg/ ml for MSSA

Summary

Introduction

The overall MRSA prevalence in India has been reported as 42% in 2008 and 40% in 2009. The efficacy of teicoplanin, in terms of clinical and microbiological cure, has not been proven to be superior to vancomycin, but it has a better toxicity profile and has demonstrated a reduced risk of adverse events.[4] The recently developed antimicrobial drug linezolid, the first of new class of antibiotics, the oxazolidiones, is available. The aim of the present study is determine risk factors association with MRSA as compared with MSSA and to compare the minimum inhibitory concentrations (MICs) of vancomycin, teicoplanin, linezolid and erythromycin to MRSA and MSSA. MIC of vancomycin, teicoplanin, linezolid and erythromycin was determined by E-test (HIMEDIA) Risk factors such as immunosuppression, previous hospitalisation, surgical procedure done, invasive devices and antibiotic therapy were determined by a pre-set protocol.

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Conclusion