[Evaluation of methods commonly used in laboratories to determine the susceptibility to oxacillin among Staphylococcus sp samples isolated from a hospital in Vitória, State of Espírito Santo].

Abstract

INTRODUCTION:

The genus Staphylococcus is of great importance because of its high prevalence in hospital infections and because it presents high rates of resistance to oxacillin and other antimicrobials. Thus, evaluation of the accuracy of the phenotypic methods that are used to determine the profile of antimicrobial resistance is essential to ensure that the most appropriate therapy is chosen.

METHODS:

One hundred and fourteen strains of Staphylococcus sp (53 S. aureus and 61 CNS) were used to evaluate the accuracy of the methods of disk diffusion, agar microdilution, oxacillin screening agar and automated systems, in comparison with PCR for investigating resistance to oxacillin.

RESULTS:

The mecA gene was detected in 48 strains (42.1%), and 27 strains (23.7%) showed discrepant results in at least one of the methods (74.1% of CNS, 25.9% of S. aureus). For S. aureus, with the exception of the Microscan Walkaway, all the methods showed 100% specificity and sensitivity. In relation to CNS, the automated system and cefoxitin disk had lower accuracy.

CONCLUSIONS:

Use of two methods should be the best option for improved accuracy, especially when the diagnostic laboratory only uses an automated system or oxacillin disk diffusion test. Combination of these methods with others presented almost 100% sensitivity and specificity in our study.

• Authors: Thais Dias Lemos Kaiser, Flavia Casseli Pacheco, Alessandra Avelino de Lima, Eliezer Menezes Pereira, Katia Regina Netto Dos Santos, Ana Paula Ferreira Nunes
• Journal: Revista da Sociedade Brasileira de Medicina Tropical (Rev Soc Bras Med Trop) 2010 May-Jun Vol. 43 Issue 3 Pg. 298-303 ISSN: 1678-9849 [Electronic] Brazil
• Vernacular Title: Avaliação de métodos comumente usados em laboratórios para a determinação da suscetibilidade à oxacilina entre amostras de Staphylococcus sp, isoladas de um hospital de Vitória, Estado do Espírito Santo.
• PMID: 20563500 (Publication Type: Evaluation Study, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Bacterial Agents
• Bacterial Proteins
• Penicillin-Binding Proteins
• mecA protein, Staphylococcus aureus
• Cefoxitin
• Oxacillin

Topics

• Anti-Bacterial Agents (pharmacology)
• Bacterial Proteins (genetics)
• Cefoxitin (pharmacology)
• Humans
• Microbial Sensitivity Tests (methods)
• Oxacillin (pharmacology)
• Penicillin-Binding Proteins
• Phenotype
• Polymerase Chain Reaction
• Sensitivity and Specificity
• Staphylococcus (drug effects, isolation & purification)