Investigation of β-Lactamases in Clinical Isolates of &lt;i&gt;Staphylococcus aureus&lt;/i&gt; for Further Explanation of Borderline Methicillin Resistance

Keserű, Judit; Gál, Zsuzsanna; Barabás, György; Benkö, Ilona; Szabó, István

doi:10.1159/000088951

Cited by 18 publications

(16 citation statements)

References 34 publications

(19 reference statements)

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“…The four isolates for which the MIC of oxacillin was 4 or 8 mg/L, but which did not harbour the mecA gene, were classified as BORSA [24]. Isolates of this kind have been described previously in a few reports, mostly in a clinical setting, and the mechanism of β‐lactam resistance is not clear at the moment, but could involve increased production of β‐lactamases [24], or several amino acid substitutions in penicillin‐binding protein 2 [25]. The presence of BORSA as part of the commensal nasal flora has, to the best of our knowledge, not been described previously.…”

Section: Discussionmentioning

confidence: 99%

The population structure of Staphylococcus aureus among general practice patients from The Netherlands

Donker

Deurenberg

Driessen

et al. 2009

Clinical Microbiology and Infection

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To investigate the prevalence, the antibiotic resistance pattern and the population structure of Staphylococcus aureus, S. aureus isolates from the anterior nostrils of patients of general practitioners (GPs) were analysed. Insight into the S. aureus population structure is essential, as nasal carriers of S. aureus are at increased risk of developing an S. aureus infection. S. aureus was isolated from nasal swabs from 2691 patients with no sign of an infection collected in 29 GP practices in The Netherlands. The susceptibility pattern for several classes of antibiotics was determined, as well as the S. aureus genetic background, using spa typing. S. aureus was isolated from 617 of the 2691 (23%) nasal swabs. The prevalences of resistance to ciprofloxacin, co-trimoxazole, fusidic acid, macrolides and mupirocin were 0.2%, 0%, 6%, 5% and 1%, respectively. Half of the isolates were associated with a genetic background common to the major methicillin-resistant S. aureus (MRSA) clones, e.g. clonal complex (CC)1, CC5, CC8, CC22, CC30 and CC45, and the remainder were mainly associated with CC7, CC12, CC15, CC26, CC51 and CC101. The low prevalences of resistance suggest that, in the Dutch situation, S. aureus isolates from patients visiting their GP because of complaints not related to infection do not represent a large reservoir of antibiotic resistance genes. Although no MRSA isolates were found, the genetic background of some of the S. aureus isolates is commonly observed among community-associated (CA)-MRSA clones (CC1, CC8 and CC30), and this might suggest that these isolates have the potential to become CA-MRSA.

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Section: Discussionmentioning

confidence: 99%

The population structure of Staphylococcus aureus among general practice patients from The Netherlands

Donker

Deurenberg

Driessen

et al. 2009

Clinical Microbiology and Infection

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“…These strains are known as borderline oxacillin-resistant S. aureus . The second mechanisms involve the production of modified PBPs with low affinity for oxacillin, and these strains are called modified penicillin-binding protein S. aureus [27,28,29,30]. …”

Section: Introductionmentioning

confidence: 99%

Oxacillin Resistance and Antimicrobial Susceptibility Profile of Staphylococcussaprophyticus and Other Staphylococci Isolated from Patients with Urinary Tract Infection

Ferreira¹,

Bonesso²,

Mondelli

et al. 2012

Chemotherapy

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Background:Staphylococcus saprophyticus is the second most frequent community-acquired causative agent of urinary tract infection (UTI). The objective of this study was to evaluate the susceptibility profile and resistance detection in Staphylococcus species. isolated from patients with UTI. Materials and Methods: The isolates were investigated using the disk diffusion method, Vitek I system, E-test®, and detection of the mecA gene. Results: Most isolates (76.2%) were resistant to oxacillin by the disk diffusion method, followed by those resistant to penicillin (72.2%). The oxacillin disk diffusion method, E-test, and Vitek I method showed higher sensitivity (94.4%) and lower specificity (28.9, 26.5, and 24.0%, respectively) than the cefoxitin disk diffusion test (sensitivity: 83.5%, specificity: 85.5%) for the detection of oxacillin resistance. Conclusions: The large number of oxacillin-resistant isolates indicates that the breakpoint value recommended by the Clinical and Laboratory Standards Institute may overestimate oxacillin resistance in S. saprophyticus. Thus, changes in these guidelines are necessary for the correct detection of this resistance.

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“…Resistance of S. aureus to oxacillin is mainly associated with the presence of the mecA gene; however, other types of resistance, called borderline resistance, have also been identified in strains that do not car-ry this gene. Borderline resistance is the result of two mechanisms: inactivation of oxacillin mediated by the hyperproduction of ␤ -lactamase [4,5] , or a modified resistance, called MOD-SA, which is mediated by the production of modified penicillin-binding proteins with altered affinity for oxacillin [4] .…”

Section: Introductionmentioning

confidence: 99%

Oxacillin Resistance of <i>Staphylococcus aureus</i> Isolated from the University Hospital of Botucatu Medical School in Brazil

Martins

Pereira²,

Cunha³

2010

Chemotherapy

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Background: Oxacillin is the main drug used for the treatment of Staphylococcus aureus infections. However, resistance of S. aureus to oxacillin has become a major problem over recent decades. The aim of this study was to determine oxacillin resistance in S. aureus isolates obtained from the University Hospital of the Botucatu Medical School, Universidade Estadual Paulista, Brazil. Materials and Methods: A total of 102 isolates collected between 2002 and 2006 were analyzed by detection of the mecA gene, cefoxitin and oxacillin disk diffusion methods, screening test on Mueller-Hinton agar and E-test. Results: Forty-six (45.1%) isolates were mecA positive. The oxacillin disk diffusion method showed 86.9% sensitivity and 91.1% specificity. The screening method and cefoxitin disk diffusion presented a similar sensitivity (91.3%) and the same specificity. The E-test showed 97.8% sensitivity and the same specificity as observed for the other methods. Conclusions: The E-test yielded the best results compared to the other methods.

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Investigation of β-Lactamases in Clinical Isolates of <i>Staphylococcus aureus</i> for Further Explanation of Borderline Methicillin Resistance

Cited by 18 publications

References 34 publications

The population structure of Staphylococcus aureus among general practice patients from The Netherlands

The population structure of Staphylococcus aureus among general practice patients from The Netherlands

Oxacillin Resistance and Antimicrobial Susceptibility Profile of Staphylococcussaprophyticus and Other Staphylococci Isolated from Patients with Urinary Tract Infection

Oxacillin Resistance of <i>Staphylococcus aureus</i> Isolated from the University Hospital of Botucatu Medical School in Brazil

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