Methicillin-resistant Staphylococcus lugdunensis carrying SCCmec type V misidentified as MRSA

Staphylococcus lugdunensis is a rare cause of severe infections and clinical manifestations are similar to those related to S. aureus infection. We describe a hospital-acquired bacteremia due to methicillin-resistant Staphylococcus lugdunensis, misidentified as methicillin-resistant S. aureus. The oxacillin MIC was 16 µg/mL and the mecA gene and SCCmec type V were determined by PCR. Although treatment had been appropriated, the patient died after rapid progressive respiratory failure and another nosocomial sepsis. It is important not only to identify S. lugdunensis in view of its clinical course, but also to determine its susceptibility to oxacillin by detecting the mecA gene or its product.

First report of the blaOXA-58 gene in a clinical isolate of Acinetobacter baumannii in Rio de Janeiro, Brazil

Carbapenemase production is an important mechanism of carbapenem resistance among nonfermentative Gram-negative isolates. This study aimed to report the detection of blaOXA-58 gene in multiresistant clinical isolates of Acinetobacter baumannii recovered from inpatients in a public hospital. Polymerase chain reaction tests were performed to detect the blaOXA-23-like, blaOXA-24-like, blaOXA-58-like and blaOXA-51-like genes. The blaOXA-58 and blaOXA-23 genes were detected in one and three isolates, respectively. Sequencing of the blaOXA-58-like amplicon revealed 100 percent identity with the A. baumannii blaOXA-58 gene listed in the GenBank database. This is the first report of an OXA-58-producing A. baumannii isolate in Rio de Janeiro, Brazil.

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 / 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

INTRODUÇÃO: O gênero Staphylococcus é de grande importância devido a sua alta prevalência em infecções hospitalares e por apresentar taxas elevadas de resistência a oxacilina e a outros antimicrobianos. Assim, a avaliação da acurácia dos métodos fenotípicos usados para determinação do perfil de suscetibilidade a antimicrobianos é essencial para garantir a escolha da terapia mais adequada. MÉTODOS: Foram usadas 114 amostras de Staphylococcus sp (53 S. aureus e 61 SCN) na avaliação da acurácia dos métodos de difusão de disco, microdiluição em agar, ágar triagem oxacilina e sistema automatizado em comparação com a PCR para verificação da resistência a oxacilina. RESULTADOS: O gene mecA foi detectado em 48 (42,1 por cento) amostras e 27 (23,7 por cento) amostras apresentaram discrepância de resultados em pelo menos um dos métodos (74,1 por cento SCN, 25,9 por cento S. aureus). Para S. aureus, com exceção do Microscan Walkaway, todos os métodos apresentaram 100 por cento de especificidade e sensibilidade. Já para os SCN, o sistema automatizado e o disco de cefoxitina apresentaram menor acurácia. CONCLUSÕES: O uso de dois métodos deve ser a melhor opção para a melhora da acurácia, principalmente quando o laboratório de diagnóstico utiliza somente sistema automatizado ou teste de difusão do disco de oxacilina. A associação destes métodos com outros apresentaram praticamente 100 por cento de sensibilidade e especificidade em nosso estudo.

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 percent), and 27 strains (23.7 percent) showed discrepant results in at least one of the methods (74.1 percent of CNS, 25.9 percent of S. aureus). For S. aureus, with the exception of the Microscan Walkaway, all the methods showed 100 percent 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 percent sensitivity and specificity in our study.