A Comparative Analysis of GeneXpert Real-Time PCR with Culture for the Detection of Methicillin-Resistant Staphylococcus aureus Colonization in Selected Hospital Admissions

Fuzhan Parhizgar,Richard Winn,Jodene Satterwhite,Kenneth Nugent,Jane Colmer-Hamood

doi:10.5402/2013/463084

Abstract

Contact isolation of patients with methicillin-resistant Staphylococcus aureus (MRSA) reduces transmission to other patients and to health care workers. PCR technology can provide rapid detection of these patients. We tested the utility of using PCR for MRSA detection in patients with a history of MRSA infection or colonization or in a high risk group admitted to a general referral hospital. Nasal swabs from 342 patients were tested for MRSA on days one and three using the GeneXpert MRSA system. Swabs with a positive PCR result were cultured to identify staphylococcal species present in the nares. Fifty-six patients (38% of 147) with a history of MRSA colonization or infection were positive; forty-seven patients (24% of 195) in a high risk group were positive. Eighty-one percent of the patients with positive PCR swabs grew out MRSA on culture. Some cultures grew out only methicillin-sensitive Staphylococcus aureus, methicillin-sensitive, coagulase negative Staphylococcus, or methicillin-resistant, coagulase negative Staphylococcus. This study demonstrates that most patients at risk for MRSA colonization are not colonized and that microbiological surveillance using PCR technology can facilitate contact isolation decisions. Not all PCR positive results represent the presence of MRSA, and hospitals need to consider policies for additional evaluation of positive PCR tests.

Highlights

Methicillin-resistant Staphylococcus aureus (MRSA) causes skin and so tissue infections, sepsis, osteomyelitis, meningitis, endocarditis, urinary tract infections, necrotizing pneumonia, and toxic shock syndrome. ese infections occur more frequently in men and in patients with signi cant comorbidity and increase hospital stays, mortality rates, and total costs [1]
We studied nasal colonization rates with methicillin-resistant Staphylococcus aureus (MRSA) in selected groups of patients rather than in all admissions or in particular patient care units to determine how useful faster diagnostic tests based on polymerase chain reaction (PCR) identi cation would be in screening these patients
Our study demonstrates that 38% of patients with a history of MRSA colonization or infection were nasal carriers upon readmission to the hospital and required contact isolation and that 24% of patients in a risk group were current carriers and required contact isolation. erefore, these results demonstrate that microbiological surveillance with selective screening using rapid detection methods with PCR technology facilitates decisions regarding contact isolation. is approach should reduce transmission of MRSA from patients to healthcare workers and other patients and limit the use of unnecessary isolation. is approach should be more cost effective than using universal screening [4]

Summary

Introduction

Methicillin-resistant Staphylococcus aureus (MRSA) causes skin and so tissue infections, sepsis, osteomyelitis, meningitis, endocarditis, urinary tract infections, necrotizing pneumonia, and toxic shock syndrome. ese infections occur more frequently in men and in patients with signi cant comorbidity and increase hospital stays, mortality rates, and total costs [1]. In the early 1990s, hospitals started to use more stringent contact isolation guidelines for patients colonized or infected with MRSA to prevent the spread to other patients in the hospital [2]. Many patients are not permanent carriers a er infection or colonization and do not need full contact precautions and isolation upon readmission. Some hospitals screen patients for MRSA infection upon admission, and these protocols range from patients in selected patient care units to universal screening of all patients [3, 4]. We studied nasal colonization rates with MRSA in selected groups of patients rather than in all admissions or in particular patient care units to determine how useful faster diagnostic tests based on polymerase chain reaction (PCR) identi cation would be in screening these patients

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