Analysis of Borderline Oxacillin-Resistant Staphylococcus aureus (BORSA) Strains Isolated in Tunisia

Maâlej, Sami; Rhimi, Faouzia; Fines, Marguerite; Mnif, Basma; Leclercq, Roland; Hammami, Adnène

doi:10.1128/jcm.01354-12

Cited by 30 publications

(25 citation statements)

References 25 publications

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“…All strains were confirmed to be phenotypically methicillin resistant, demonstrating zones of inhibition ranging from undetectable to 14 mm with the cefoxitin disk diffusion test. It is likely that the resistances in these strains were mediated by mecA as opposed the overexpression of a penicillinase, which typically results in cefoxitin zones of inhibition of Ն28 mm (35). MRSA harboring mecC will display high-level phenotypic resistance to cefoxitin, which is consistent with the MRSA strains not detected by the GeneOhm assay in this study.…”

Section: Discussionsupporting

confidence: 76%

Comparison of the Next-Generation Xpert MRSA/SA BC Assay and the GeneOhm StaphSR Assay to Routine Culture for Identification of Staphylococcus aureus and Methicillin-Resistant S. aureus in Positive-Blood-Culture Broths

et al. 2015

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A bloodstream infection with Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), is a serious condition that carries a high mortality rate and is also associated with significant hospital costs. The rapid and accurate identification and differentiation of methicillin-susceptible S. aureus (MSSA) and MRSA directly from positive blood cultures has demonstrated benefits in both patient outcome and cost-of-care metrics. We compare the next-generation Xpert MRSA/SA BC (Xpert) assay to the GeneOhm StaphSR (GeneOhm) assay for the identification and detection of S. aureus and methicillin resistance in prospectively collected blood culture broths containing Gram-positive cocci. All results were compared to routine bacterial culture as the gold standard. Across 8 collection and test sites, the Xpert assay demonstrated a sensitivity of 99.6% (range, 96.4% to 100%) and a specificity of 99.5% (range, 98.0% to 100%) for identifying S. aureus, as well as a sensitivity of 98.1% (range, 87.5% to 100%) and a specificity of 99.6% (range, 98.3% to 100%) for identifying MRSA. In comparison, the GeneOhm assay demonstrated a sensitivity of 99.2% (range, 95.2% to 100%) and a specificity of 96.5% (range, 89.2% to 100%) for identifying S. aureus, as well as a sensitivity of 94.3% (range, 87.5% to 100%) and a specificity of 97.8% (range, 96.1% to 100%) for identifying MRSA. Five of six cultures falsely reported as negative for MRSA by the GeneOhm assay were correctly identified as positive by the Xpert assay, while one culture falsely reported as negative for MRSA by the Xpert assay was correctly reported as positive by the GeneOhm assay. Bloodstream infection (BSI) is a serious condition, resulting in Ͼ500,000 hospitalizations per year in the United States, accounting for up to 11% of intensive care unit admissions (1, 2). Mortality associated with BSI can range from 25% to 80%, depending on underlying illnesses, and it is higher in nosocomial versus community-acquired infections (3-5). Bloodstream infections also carry a high monetary burden, ranging from $36,000 to $40,000 in additional expenses per patient as a result of prolonged hospitalization (4-6). The leading causes of community-and hospital-acquired BSI are Staphylococcus aureus, Staphylococcus epidermidis, and various other coagulase-negative Staphylococcus (CoNS) species (5, 7). Within this group of organisms, infection with methicillin-resistant S. aureus (MRSA) is most critical and has been associated with a mortality rate 1.70 to 1.93 times higher than that of methicillin-susceptible S. aureus (MSSA) strains (8, 9). The outcome of these infections can be positively impacted by early diagnosis and effective antimicrobial therapy (10-12). Rapid diagnostic methods, such as peptide nucleic acid fluorescence in situ hybridization (PNA FISH), matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and nucleic acid amplification and detection have been successfully applied to directly analyze positive blood culture broths ...

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Section: Discussionsupporting

confidence: 76%

Comparison of the Next-Generation Xpert MRSA/SA BC Assay and the GeneOhm StaphSR Assay to Routine Culture for Identification of Staphylococcus aureus and Methicillin-Resistant S. aureus in Positive-Blood-Culture Broths

et al. 2015

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“…31,32 Typically BORSA isolates are not resistant to multiple agents 33 and are believed to have little relevance. 34,35 However, in our analysis, BORSA isolates demonstrated several resistance patterns. Further molecular analysis is necessary to better understand the epidemiology of this resistance pattern and to determine whether these isolates are responsible for substantial morbidity in southern Africa.…”

Section: Discussionmentioning

confidence: 50%

Prevalence of Staphylococcus aureus Nasal Carriage in Human Immunodeficiency Virus–Infected and Uninfected Children in Botswana: Prevalence and Risk Factors

Reid

Fischer

Mannathoko

et al. 2017

The American Society of Tropical Medicine and Hygiene

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Abstract. Staphylococcus aureus is an important cause of morbidity and mortality in children in sub-Saharan Africa (SSA). A major risk factor for staphylococcal infection is S. aureus colonization of the anterior nares. We sought to define risk factors for S. aureus carriage and characterize antimicrobial resistance patterns in children in Botswana. A cross-sectional study was conducted at two clinical sites in southern Botswana. Patients under 18 years of age underwent two nasal swabs and brief interviews, 4 weeks apart. Standard microbiological techniques were used. For persistent carriers, S. aureus was isolated from swabs at both time points, and for intermittent carriers, S. aureus was isolated from only one swab. Poisson regression with robust variance estimator was used to compare prevalence of carriage and the resistance phenotypes. Among 56 enrollees, prevalence of S. aureus colonization was 55% (N = 31), of whom 42% (N = 13) were persistent carriers. Of human immunodeficiency virus-infected children, 64% (N = 9) were carriers. Risk factors for nasal carriage included a history of tuberculosis (prevalence ratio [PR] = 1.60; 95% confidence interval [CI] = 1.02, 2.51; P = 0.040) and closer proximity to health care (PR = 0.89; 95% CI = 0.80, 0.99; P = 0.048). Prior pneumonia was more common among persistent rather than intermittent carriers (PR = 2.64; 95% CI = 1.64, 4.23; P < 0.001). Methicillin-resistant S. aureus (MRSA) prevalence was 13%. Of isolates tested, 16% were resistant to three or more drugs (N = 7/44). In summary, children in southern Botswana are frequently colonized with S. aureus. Antibiotic resistance, especially MRSA, is also widespread. Antibiotic recommendations for treatment of staphylococcal infections in SSA should take cognizance of these resistance patterns.

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“…Thus, oxacillin AD breakpoint of 0.5 mg/l identified all (100%) of mecA-positive CoNS in the local strains, a finding supported by the data from the UK Health Protection Agency (now called: Public Health England) and the University of Cambridge, which defined MRSA by oxacillin MIC breakpoint of 0.5 mg/l [27]. Similar mecA-positive staphylococci with low-level oxacillin MIC have been reported elsewhere [28,29]. The increased detection from 99.19% by DD (both OX1 and CX30 discs) to 100% by AD breakpoint of 0.5 mg/l oxacillin in this study is supported by another report in which all mecA-positive CoNS isolates were identified when the oxacillin concentration was decreased from 6.0 to 0.6 mg/l [30].…”

Section: Reference and Local Bacterial Strains Validate The New Pentasupporting

confidence: 53%

Development of a new pentaplex real-time PCR assay for the identification of poly-microbial specimens containing Staphylococcus aureus and other staphylococci, with simultaneous detection of staphylococcal virulence and methicillin resistance markers

Okolie

Wooldridge

Turner

et al. 2015

Molecular and Cellular Probes

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Analysis of Borderline Oxacillin-Resistant Staphylococcus aureus (BORSA) Strains Isolated in Tunisia

Cited by 30 publications

References 25 publications

Comparison of the Next-Generation Xpert MRSA/SA BC Assay and the GeneOhm StaphSR Assay to Routine Culture for Identification of Staphylococcus aureus and Methicillin-Resistant S. aureus in Positive-Blood-Culture Broths

Comparison of the Next-Generation Xpert MRSA/SA BC Assay and the GeneOhm StaphSR Assay to Routine Culture for Identification of Staphylococcus aureus and Methicillin-Resistant S. aureus in Positive-Blood-Culture Broths

Prevalence of Staphylococcus aureus Nasal Carriage in Human Immunodeficiency Virus–Infected and Uninfected Children in Botswana: Prevalence and Risk Factors

Development of a new pentaplex real-time PCR assay for the identification of poly-microbial specimens containing Staphylococcus aureus and other staphylococci, with simultaneous detection of staphylococcal virulence and methicillin resistance markers

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