Does Nasal Cocolonization by Methicillin-Resistant Coagulase-Negative Staphylococci and Methicillin-Susceptible
            <i>Staphylococcus aureus</i>
            Strains Occur Frequently Enough To Represent a Risk of False-Positive Methicillin-Resistant
            <i>S. aureus</i>
            Determinations by Molecular Methods?

Becker, Karsten; Pagnier, Isabelle; Schuhen, Brigitte; Wenzelburger, Frauke; Friedrich, Alexander; Kipp, Frank; Peters, Georg; Eiff, Christof von

doi:10.1128/jcm.44.1.229-231.2006

Cited by 116 publications

(81 citation statements)

References 24 publications

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“…S. aureus accounted for 23.1％ of all staphylococcus isolates, and was were only isolated from one subject（the same individual） , whereas S. capitis was isolated from two subjects. These results were similar to those obtained in previous studies (17,19) and indicated that S. epidermidis is the most predominant Staphylococcus species in the nasal cavity.…”

Section: Discussionsupporting

confidence: 82%

Frequency of Staphylococci in the Nasal Cavities of Healthy Medical Workers

Omine¹,

Tsuzukibashi²,

Uchibori³

et al. 2013

Int J Oral-Med Sci

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Infective agents are abundant in hospitals, and so medical staff members are often exposed to them. Although previous studies have highlighted the role played by the nasal flora of medical staff in the development of nosocomial infections, few studies have specifically investigated this issue. Six volunteer medical staff members, who worked at Nihon University Hospital at Matsudo, participated in this study. Nasal samples were obtained from the medical staff, and then the samples were cultured and evaluated using routine bacteriological study methods. Staphylococci were detected in the nasal samples of all of the medical staff. Staphylococcus epidermidis was the predominant species in their nasal cavities（71.3％） . None of the medical staff had been infected with methicillin-resistant Staphylococcus aureus（MRSA） , but four of six staff members possessed methicillinresistant coagulase-negative staphylococci（MR-CNS） .Medical staff members are both at risk of infection and also a potential source of nosocomial pathogens such as methicillin-resistant staphylococci. As a preventive measure against nosocomial infection, it might be necessary to continuously investigate the frequency of methicillin-resistant staphylococci in the nasal cavities of medical staff.

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Section: Discussionsupporting

confidence: 82%

Frequency of Staphylococci in the Nasal Cavities of Healthy Medical Workers

Omine¹,

Tsuzukibashi²,

Uchibori³

et al. 2013

Int J Oral-Med Sci

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“…Therefore, the MRCoNS-MSSA cocolonization rate in a given population must be taken into account because it can negatively impact the specificity of third-generation MRSA screening tests. Becker et al have addressed this question and reported a 3.4% rate of MRCoNS-MSSA nasal cocolonization in German cardiothoracic surgery patients upon admission (11). However, we raised the hypothesis that this rate could be higher in patients hospitalized in wards with high antibiotic pressure, such as intensive care units (ICUs), the population of which represents, in most countries, the population primarily targeted for MRSA screening.…”

mentioning

confidence: 54%

“…1) (9). As the mecA gene is present in both MRSA and methicillin-resistant coagulase-negative staphylococci (MRCoNS) (10), specificity of this first generation of MRSA screening tests in clinical specimens can be altered by MSSA and MRCoNS cocolonization (11). To cope with this issue, the second-generation MRSA screening tests used a set of primers targeting the junction sequence between SCCmec and the S. aureus chromosome.…”

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confidence: 99%

Ward-Specific Rates of Nasal Cocolonization with Methicillin-Susceptible and -Resistant Staphylococcus spp. and Potential Impact on Molecular Methicillin-Resistant Staphylococcus aureus Screening Tests

et al. 2013

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eWe report that the rates of nasal cocolonization with methicillin-susceptible Staphylococcus aureus and methicillin-resistant coagulase-negative staphylococci can vary widely between patients admitted to different wards within a single hospital. Such cocolonization can greatly influence the performance of molecular methicillin-resistant S. aureus (MRSA) screening tests depending on the methods used and targets selected. Staphylococci, especially methicillin-resistant Staphylococcus aureus (MRSA) strains, are major pathogens implicated in nosocomial infections, and the link between S. aureus nasal colonization and staphylococcal disease has been well established (1), with nosocomial S. aureus bacteremia being three times more frequent in S. aureus carriers than in noncarriers (2). Moreover, Safdar and Bradley underlined the importance of MRSA carrier detection by showing that patients colonized with MRSA were four times more likely to develop invasive infections than patients colonized with methicillin-sensitive S. aureus (MSSA) (3). Finally, MRSA infections are associated with a high financial burden. For example, the cost of management for patients with an orthopedic device infection due to MRSA is estimated at $100,000 per case, representing a 50% additional cost compared to that of MSSA infections (4).In this context, several manufacturers have developed rapid molecular MRSA screening tests as an alternative to conventional culture methods (5-8). Staphylococcal methicillin resistance is encoded by the mecA gene, located on a mobile genetic element designated the staphylococcal cassette chromosome mec (SCCmec) acquired by horizontal transfer and chromosomic insertion. Different generations of MRSA molecular tests have been successively developed using different combinations of genetic targets. The first-generation tests rely on the combined amplification of the mecA gene and of an S. aureus-specific gene such as spa (Fig. 1) (9). As the mecA gene is present in both MRSA and methicillin-resistant coagulase-negative staphylococci (MRCoNS) (10), specificity of this first generation of MRSA screening tests in clinical specimens can be altered by MSSA and MRCoNS cocolonization (11). To cope with this issue, the second-generation MRSA screening tests used a set of primers targeting the junction sequence between SCCmec and the S. aureus chromosome. Specifically, one primer targets an S. aureus-specific sequence near the SCCmec insertion site located in the orfX gene, and another primer targets an SCCmecspecific sequence. Hence, the amplification detects the presence of the SCCmec element only when it is inserted in the S. aureus genome, thus eliminating interference due to MRCoNS. Nevertheless, it had been demonstrated that this detection method can still give a falsepositive result in the presence of S. aureus isolates harboring an SCC element lacking the mecA gene; such isolates are designated mecA dropout isolates (12, 13). These SCC-positive, methicillin-susceptible S. aureus (MSSA) isolates are misidentified as...

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“…The sizes of the amplicons were 530bp and 280bp for mecA and nuc genes, respectively. S. aureus ATCC 33592 was used as positive control for mecA and nuc genes and S. aureus ATCC 29213 was used as positive control for only nuc gene, while S. epidermidis DSM 20044 was used as negative control [34,35].…”

Section: Isolation and Identification Of S Aureus And Mrsamentioning

confidence: 99%