Abstract Background: The increasingly frequent use of dermoscopy makes us think about the possibility of transfer of microorganisms, through the dermatoscope, between doctor and patients. Objectives: To identify the most frequent gram-positive cocci in dermatoscopes and smartphone adapters, as well as the resistance profile, and to evaluate the factors associated with a higher risk of bacterial contamination of the dermatoscopes. Methods: A cross-sectional study was carried out with 118 dermatologists from Porto Alegre/Brazil between September 2017 and July 2018. Gram-positive cocci were identified by MALDI-TOF MS and habits of use of the dermatoscope were evaluated through an anonymous questionnaire. Results: Of the dermatoscopes analysed, 46.6% had growth of gram-positive cocci on the lens and 37.3% on the on/off button. The microorganisms most frequently found were S. epidermidis, S. hominis and S. warneri. Attending a hospital, using the dermatoscope at the hospital, with inpatients and in the intensive care unit were significantly associated with colonisation by gram-positive cocci. The highest resistance rates were observed for penicillin, erythromycin and sulfamethoxazole-trimethoprim. Study limitations: The non-search of gram-negative bacilli, fungi and viruses. Moreover, the small number of adapters did not make it possible to better define if the frequency differences were statistically significant. Conclusion: Coagulase-negative staphylococci were frequently identified. S. aureus was detected only on the lens.

Abstract: Background: Topical antimicrobial drugs are indicated for limited superficial pyodermitis treatment, although they are largely used as self-prescribed medication for a variety of inflammatory dermatoses, including atopic dermatitis. Monitoring bacterial susceptibility to these drugs is difficult, given the paucity of laboratory standardization. Objective: To evaluate the prevalence of Staphylococcus aureus topical antimicrobial drug resistance in atopic dermatitis patients. Methods: We conducted a cross-sectional study of children and adults diagnosed with atopic dermatitis and S. aureus colonization. We used miscellaneous literature reported breakpoints to define S. aureus resistance to mupirocin, fusidic acid, gentamicin, neomycin and bacitracin. Results: A total of 91 patients were included and 100 S. aureus isolates were analyzed. All strains were methicillin-susceptible S. aureus. We found a low prevalence of mupirocin and fusidic acid resistance (1.1% and 5.9%, respectively), but high levels of neomycin and bacitracin resistance (42.6% and 100%, respectively). Fusidic acid resistance was associated with more severe atopic dermatitis, demonstrated by higher EASI scores (median 17.8 vs 5.7, p=.009). Our results also corroborate the literature on the absence of cross-resistance between the aminoglycosides neomycin and gentamicin. Conclusions: Our data, in a southern Brazilian sample of AD patients, revealed a low prevalence of mupirocin and fusidic acid resistance of S. aureus atopic eczema colonizer strains. However, for neomycin and bacitracin, which are commonly used topical antimicrobial drugs in Brazil, high levels of resistance were identified. Further restrictions on the use of these antimicrobials seem necessary to keep resistance as low as possible.

Abstract: INTRODUCTION: Coagulase-negative staphylococci (CoNS) are the most prevalent pathogens in nosocomial infections and may serve as a reservoir of mobile genetic elements such as the staphylococcal cassette chromosome mec (SCCmec) encoding methicillin resistance. Molecular characterization of SCCmec types combined with advanced molecular typing techniques may provide essential information for understanding the evolution and epidemiology of CoNS infections. We therefore aimed to investigate the SCCmec distribution, multidrug-resistance (MDR), and biofilm formation in CoNS blood culture isolates from a hospital in Southern Brazil. METHODS: We analyzed 136 CoNS blood culture isolates obtained during 2002-2004 from patients admitted to a tertiary care hospital in Brazil. SCCmec types I to V were determined using multiplex PCR. The clonal relationship of Staphylococcus epidermidis was determined using pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Molecular epidemiological data were interpreted along with data on biofilm formation, presence of the icaD gene, and MDR. RESULTS: The most prevalent species were S. epidermidis, Staphylococcus haemolyticus, and Staphylococcus hominis harboring mainly SCCmec types II, III, and V. Overall, the presence of multiple SCCmec was associated with non-MDR, except for S. epidermidis. S. epidermidis isolates showed a high prevalence of icaD, but had low phenotypic biofilm formation. PFGE and MLST revealed high genetic diversity in the S. epidermidis population. CONCLUSIONS: Our results suggest a major shift in SCCmec types within a short period and reveal a different behavior of S. epidermidis with regard to the association between the presence of multiple SCCmec types and MDR profile.

ABSTRACTTo determine the epidemiological and molecular characteristics of 12 Staphylococcus aureus isolates presenting heteroresistance to vancomycin in laboratories of two cities in Santa Catarina, southern Brazil. Epidemiological data, including the city of isolation, health institution, and date of isolation were considered, as well as the associated clinical specimen. For molecular characterization, we analyzed the staphylococcal cassette chromosome types, the erm gene presence, and the genomic diversity of isolates using pulsed-field gel electrophoresis. The 12 isolates of S. aureus were previously confirmed as heteroresistance to vancomycin using the population analysis profile-area under curve. Regarding genetic variability, two clones were detected: the main one (clone A) composed of four isolates and the clones B, with two isolates. For clone A, two isolates presented identical band patterns and were related to the same hospital, with an interval of 57 days between their isolation. The other isolates of this clone showed no epidemiological link between them because they were isolated in different hospitals and had no temporal relationship. The other clone showed no detectable epidemiological relationship. The heteroresistance to vancomycin recovered in Santa Catarina State from 2009 to 2012 had, in general, heterogeneous genomic patterns based on pulsed-field gel electrophoresis results, which is in accordance with the fact that these isolates had little or no epidemiological relationship among them. Due to the characteristic phenotypic instability and often prolonged vancomycin therapy for selection, clonal spread is not as common as for other resistance mechanisms disseminated through horizontal gene transfer.

ABSTRACTINTRODUCTION:Exposure to subinhibitory concentrations (SICs) of antimicrobials may alter the bacterial transcriptome.METHODS: Here, we evaluated the expression of nine virulence-related genes in vancomycin-resistant enterococci (VRE) urinary tract infection isolates grown at SICs of vancomycin.RESULTS:A Subinhibitory concentrations of vancomycin interferes with gene modulation, but does not affect the phenotype of a VRE strain in vitro .CONCLUSIONS:Subinhibitory concentrations of vancomycin may regulate the expression of virulence factors in vivo or contribute to the selection of vancomycin-resistant strains.

INTRODUÇÃO: Staphylococcus aureus resistente à meticilina (MRSA) apresentando suscetibilidade reduzida à vancomicina tem sido associado à falha terapêutica. Alguns métodos utilizados por laboratórios clínicos podem não ser suficientemente precisos para detectar este fenótipo, comprometendo os resultados e o desfecho do paciente. OBJETIVOS: Avaliar o desempenho de métodos na detecção dos valores de MIC de vancomicina entre isolados clínicos de MRSA. MATERIAIS E MÉTODOS: Determinamos a Concentração Inibitória Mínima de Vancomicina para 75 MRSA isolados de pacientes do Hospital Mãe de Deus, Porto Alegre, Brasil. Utilizamos a microdiluição em caldo como técnica padrão-ouro e os seguintes métodos: tiras de E-test® (BioMérieux), tiras M.I.C.E® (Oxoid), painel comercial da PROBAC® e sistema automatizado MicroScan® (Siemens). Além disso, foi realizado o teste de triagem em ágar com 3 µg/mL de vancomicina. RESULTADOS: Todos os isolados apresentaram MIC ≤ 2 µg/mL. Não houve diferença estatística entre os resultados do E-test® e da microdiluição em caldo. O painel da PROBAC® apresentou MICs, em geral, menores que o padrão-ouro (58,66% de erros maiores), enquanto que as MICs pelo M.I.C.E.® foram maiores (67,99% de erros menores). CONCLUSÕES: Para nossa população de MRSA, E-test® apresentou o melhor desempenho, embora com uma acurácia heterogênea, dependendo dos valores da MIC.

INTRODUCTION: Methicillin-Resistant Staphylococcus aureus (MRSA) presenting reduced susceptibility to vancomycin has been associated to therapeutic failure. Some methods used by clinical laboratories may not be sufficiently accurate to detect this phenotype, compromising results and the outcome of the patient. OBJECTIVES: To evaluate the performance of methods in the detection of vancomycin MIC values among clinical isolates of MRSA. MATERIAL AND METHODS: The Vancomycin Minimal Inhibitory Concentration was determined for 75 MRSA isolates from inpatients of Mãe de Deus Hospital, Porto Alegre, Brazil. The broth microdilution (BM) was used as the gold-standard technique, as well as the following methods: E-test® strips (BioMérieux), M.I.C.E® strips (Oxoid), PROBAC® commercial panel and the automated system MicroScan® (Siemens). Besides, the agar screening test was carried out with 3 µg/mL of vancomycin. RESULTS: All isolates presented MIC ≤ 2 µg/mL for BM. E-test® had higher concordance (40%) in terms of global agreement with the gold standard, and there was not statistical difference among E-test® and broth microdilution results. PROBAC® panels presented MICs, in general, lower than the gold-standard panels (58.66% major errors), while M.I.C.E.® MICs were higher (67.99% minor errors). CONCLUSIONS: For the population of MRSA in question, E-test® presented the best performance, although with a heterogeneous accuracy, depending on MIC values.

Contexto:A infecção de ferida operatória é uma complicação grave da cirurgia vascular periférica e está associada a elevadas taxas de morbidade e mortalidade.Objetivo:Avaliar a morbidade e a mortalidade relacionadas às infecções de ferida operatória causadas por micro-organismos resistentes em cirurgias arteriais periféricas.Métodos:Coorte prospectiva envolvendo pacientes submetidos a procedimentos de revascularização arterial periférica que desenvolveram infecção de sítio cirúrgico, entre março de 2007 e março de 2011.Resultados:A média de idade desses pacientes foi de 63,7 anos; homens representaram 64,3% de todos os casos. A prevalência total de resistência bacteriana foi de 65,7%. O micro-organismo mais isolado foi o Staphylococcus aureus (30%). Comparando-se as características demográficas e cirúrgicas das duas amostras (com e sem resistência), foi demonstrado que o tempo de permanência hospitalar apresentou diferença significativa (9,3 dias × 3,7 dias). O grupo de pacientes portadores de infecção por micro-organismo resistente apresentou elevadas taxas de reoperação, amputação de membro inferior e mortalidade, porém sem diferença estatística quando comparado ao grupo sem resistência. No longo prazo, a sobrevida foi similar.Conclusão:este estudo não demonstrou diferença estatística quanto a morbidade e mortalidade entre os grupos com infecção de ferida operatória ocasionada por micro-organismos resistentes e não resistentes.

Background:Surgical site infection is a severe complication of peripheral vascular surgery with high morbidity and mortality rates.Objective:To evaluate the morbidity and mortality of infections of peripheral artery surgery sites caused by resistant microorganisms.Methods:This was a prospective study of a cohort of patients who underwent peripheral artery revascularization procedures and developed surgical site infections between March 2007 and March 2011.Results:Mean age was 63.7 years; males accounted for 64.3% of all cases. The overall prevalence of bacterial resistance to antimicrobials was 65.7%. The most common microorganism identified was Staphylococcus aureus (30%). Comparison of the demographic and surgical characteristics of both subsets (resistant versus non-resistant) detected a significant difference in length of preoperative hospital stay (9.3 days vs. 3.7 days). The subset of patients with infections by resistant microorganisms had higher rates of reoperation, lower numbers of limb amputations and lower mortality, but the differences compared to the subset without resistant infections were not significant. Long-term survival was similar.Conclusions:This study detected no statistically significant differences in morbidity or mortality between subsets with surgical wound infections caused by resistant and not-resistant microorganisms.

Introduction. The genera Enterococcus, Staphylococcus and Streptococcus are recognized as important Gram-positive human pathogens. The aim of this study was to evaluate the performance of Vitek 2 in identifying Gram-positive cocci and their antimicrobial susceptibilities. Methods. One hundred four isolates were analyzed to determine the accuracy of the automated system for identifying the bacteria and their susceptibility to oxacillin and vancomycin. Results. The system correctly identified 77.9% and 97.1% of the isolates at the species and genus levels, respectively. Additionally, 81.8% of the Vitek 2 results agreed with the known antimicrobial susceptibility profiles. Conclusion. Vitek 2 correctly identified the commonly isolated strains; however, the limitations of the method may lead to ambiguous findings.

Atualmente, para extrair o DNA bacteriano, existem diversos métodos baseados em diferentes princípios. Entretanto, a quantidade e qualidade do DNA obtido por cada um destes métodos é variável e depende do tipo de micro-organismo em questão; os estafilococos coagulase-negativos (CoNS), por exemplo, possuem parede celular espessa difícil de lisar. O objetivo deste estudo foi comparar a quantidade e a qualidade do DNA extraído de isolados clínicos de CoNS utilizando quatro metodologias diferentes: dois protocolos caseiros e dois kits comerciais. A determinação da quantidade e da qualidade do DNA foi realizada por espectrofotometria. O DNA extraído também foi analisado em eletroforese em gel de agarose e por PCR. A concentração média de DNA foi mais alta no método de lise térmica (). Entretanto, com relação à qualidade do DNA, o kit comercial que utiliza um método de extração baseado em uma coluna de separação apresentou melhor resultado (média da relação A260/280 = 1,95). As quatro técnicas testadas forneceram DNA passível de amplificação por PCR, porém com diferentes rendimentos. A qualidade do DNA extraído de bactérias é importante, pois possibilita a realização de maior número de técnicas de biologia molecular e também armazenamento do material por maior período de tempo. Neste sentido, a técnica de extração por coluna de separação apresentou melhor desempenho frente aos CoNS.

Currently there are several methods to extract bacterial DNA based on different principles. However, the amount and the quality of the DNA obtained by each one of those methods is highly variable and microorganism dependent, as illustrated by coagulase-negative staphylococci (CoNS) which have a thick cell wall that is difficult to lyse. This study was designed to compare the quality and the amount of CoNS DNA, extracted by four different techniques: two in-house protocols and two commercial kits. DNA amount and quality determination was performed through spectrophotometry. The extracted DNA was also analyzed using agarose gel electrophoresis and by PCR. 267 isolates of CoNS were used in this study. The column method and thermal lyses showed better results with regard to DNA quality (mean ratio of A260/280 = 1.95) and average concentration of DNA (), respectively. All four methods tested provided appropriate DNA for PCR amplification, but with different yields. DNA quality is important since it allows the application of a large number of molecular biology techniques, and also it's storage for a longer period of time. In this sense the extraction method based on an extraction column presented the best results for CoNS.

FUNDAMENTOS:A Dermatite Atópica cursa com alteração da barreira cutânea e colonização bacteriana; a relação deste último fator com a gravidade da doença e a frequência das exacerbações não é completamente conhecida.OBJETIVOS:Verificar a gravidade da Dermatite Atópica e o número de consultas ocasionadas pela dermatose, comparando pacientes colonizados e não colonizados pelo Staphylococcus aureus (S. aureus). Verificar a frequência de colonização por Staphylococcus aureus meticilina resistentes da comunidade.MÉTODOS:Estudo de coorte, com 12 meses de acompanhamento, em amostra de pacientes da rede pública de Porto Alegre, RS. Realizaram-se culturais de lesões ativas e fossas nasais e testes de sensibilidade à meticilina para o S. aureus. A gravidade da Dermatite Atópica foi estabelecida pelo Eczema Area and Severity Index.RESULTADOS:Incluídos 93 pacientes, 43% femininos e 56% masculinos, 26 colonizados por S. aureusna região nasal, 56 em lesão cutânea. A média do Eczema Area and Severity inicial foi 5,5 e a do final 3,9. O Eczema Area and Severity Index inicial dos pacientes colonizados por S. aureusem lesão cutânea e nas fossas nasais foi maior que o dos pacientes não colonizados (p< 0,05). Em um ano, seis consultas por paciente ocorreram, em média. Houve correlação linear entre o número de consultas em um ano e o Eczema Area and Severity Index inicial (r = 0,78). Não houve encontro de Staphylococcus aureus meticilina resistentes da comunidade.CONCLUSÃO:Há uma importante influência da colonização estafilocócica na gravidade da Dermatite Atópica e no número de consultas por sua exacerbação. A resistência à meticilina entre os S. aureusnão parece constituir-se como problema emergente, nesta amostra brasileira.

BACKGROUND:Atopic dermatitis leads to epidermal barrier dysfunction and bacteria colonization. The relationship of the last factor with the severity of the disease and the frequency of exacerbation is not fully known.OBJECTIVES:Verify the severity of the atopic dermatitis and the number of appointments generated by dermatosis, comparing patients colonized with patients not colonized by S. aureus. Verify the frequency of colonization by methicillin resistant Staphylococcus aureus acquired in the community.METHODS:Cohort study with a 12 months follow-up, in a sample of patients from Porto Alegre, RS public network. Cultures in active injuries and nasal cavities were carried out as well as methicillin sensitivity tests to S. aureus.The severity of atopic dermatitis was defined by Eczema Area and Severity Index (EASI).RESULTS:We included 93 patients, 43% female and 56% male, 26 colonized by S. aureusin the nasal orifices, 56 in the skin damage. The mean of initial Eczema Area and Severity Index was 5.5 and final 3.9. The initial Eczema Area and Severity Index of patients colonized by S. aureusin the skin and nasal cavity was larger than the number of patients without colonization(p< 0.05). During the period of one year, in average, there were six appointments/patient. There was linear correlation between the number of appointments during one year and the inicial Eczema Area and Severity Index (r = 0,78). There were no patients with methicillin resistant Staphylococcus aureus acquired in the community.CONCLUSION:There is a relevant influence of staphylococcal colonization on the severity of atopic dermatitis and the number of appointments required by its exacerbation. Methicillin resistance among those affected by S. aureusdoes not seem to be an emergent problem, in this Brazilian sample.

Despite the increasing importance of Enterococcus as opportunistic pathogens, their virulence factors are still poorly understood. This study determines the frequency of virulence factors in clinical and commensal Enterococcus isolates from inpatients in Porto Alegre, Brazil. Fifty Enterococcus isolates were analysed and the presence of the gelE, asa1 and esp genes was determined. Gelatinase activity and biofilm formation were also tested. The clonal relationships among the isolates were evaluated using pulsed-field gel electrophoresis. The asa1, gelE and esp genes were identified in 38%, 60% and 76% of all isolates, respectively. The first two genes were more prevalent in Enterococcus faecalis than in Enterococcus faecium, as was biofilm formation, which was associated with gelE and asa1 genes, but not with the esp gene. The presence of gelE and the activity of gelatinase were not fully concordant. No relationship was observed among any virulence factors and specific subclones of E. faecalis or E. faecium resistant to vancomycin. In conclusion, E. faecalis and E. faecium isolates showed significantly different patterns of virulence determinants. Neither the source of isolation nor the clonal relationship or vancomycin resistance influenced their distribution.

Here we report the presence and expression levels of the vanC 1 and vanC 2/3 genes in vancomycin-susceptible strains of Enterococcus faecalis. The vanC 1 and vanC 2/3 genes were located in the plasmid DNA and on the chromosome, respectively. Specific mRNA of the vanC 1 gene was detected in one of these strains. Additionally, analysis of the vanC gene sequences showed that these genes are related to the vanC genes of Enterococcus gallinarum and Enterococcus casseliflavus. The presence of vanC genes is useful for the identification of E. gallinarum and E. casseliflavus. Moreover, this is the first report of vanC mRNA in E. faecalis.

INTRODUÇÃO: Estafilococos são patógenos responsáveis por surtos de doenças transmitidas por alimentos. O estudo investigou a prevalência de genes de enterotoxinas e o perfil de resistência aos antimicrobianos em estafilococos coagulase-negativo (CoNS) e estafilococos coagulase-positivo (CoPS) isolados de morcilhas no sul do Brasil. MÉTODOS: Duzentas colônias típicas e atípicas do ágar Baird-Parker foram inoculadas em ágar sal-manitol. Oitenta e dois estafilococos manitol-positivos foram submetidos a testes bioquímicos e perfil de susceptibilidade antimicrobiana. A presença dos genes da coagulase (coa) e enterotoxinas (se) foi investigada por reação em cadeia da polimerase (PCR). RESULTADOS: Os isolados foram divididos em dois grupos: 75,6% (62/82) CoNS e 24,4% (20/82) CoPS. Através dos testes bioquímicos, 9 espécies foram determinadas, Staphylococcus saprophyticus (37,8%) e Staphylococcus carnosus (15,9%) foram as mais prevalentes. Testes de susceptibilidade demostraram fenótipos de resistência aos antibióticos administrados em humanos, como gentamicina, tetraciclina, cloranfenicol e eritromicina. O gene coa foi detectado em 19,5% (16/82) das cepas e quatro fragmentos de DNA polimórficos foram observados. Cinco CoNS contendo o gene coa foram submetidos ao sequenciamento do 16S rRNA e três mostraram similaridade com CoNS. Quarenta amostras foram positivas para pelo menos um gene se, os mais frequentes foram sea (28,6%) e seb (27,5%). CONCLUSÕES: A presença de resistência aos antimicrobianos e de genes se nos isolados de morcilha indicou que este alimento pode representar um risco potencial à saúde, já que a presença nos alimentos pode causar doenças de origem alimentar ou ser uma possível rota de transferência de estafilococos resistentes aos humanos.

INTRODUCTION: Staphylococcal species are pathogens that are responsible for outbreaks of foodborne diseases. The aim of this study was to investigate the prevalence of enterotoxin-genes and the antimicrobial resistance profile in staphylococcus coagulase-negative (CoNS) and coagulasepositive (CoPS) isolates from black pudding in southern Brazil. METHODS: Two hundred typical and atypical colonies from Baird-Parker agar were inoculated on mannitol salt agar. Eighty-two mannitol-positive staphylococci were submitted to conventional biochemical tests and antimicrobial susceptibility profiling. The presence of coagulase (coa) and enterotoxin (se) genes was investigated by polymerase chain reaction. RESULTS: The isolates were divided into 2 groups: 75.6% (62/82) were CoNS and 24.4% (20/82) were CoPS. The biochemical tests identified 9 species, of which Staphylococcus saprophyticus (37.8%) and Staphylococcus carnosus (15.9%) were the most prevalent. Antimicrobial susceptibility tests showed resistance phenotypes to antibiotics widely administered in humans, such as gentamicin, tetracycline, chloramphenicol, and erythromycin. The coa gene was detected in 19.5% (16/82) of the strains and 4 polymorphic DNA fragments were observed. Five CoNS isolates carrying the coa gene were submitted for 16S rRNA sequencing and 3 showed similarity with CoNS. Forty strains were positive for at least 1 enterotoxin-encoding gene, the genes most frequently detected were sea (28.6%) and seb (27.5%). CONCLUSIONS: The presence of antimicrobial resistant and enterotoxin-encoding genes in staphylococci isolates from black pudding indicated that this fermented food may represent a potential health risk, since staphylococci present in food could cause foodborne diseases or be a possible route for the transfer of antimicrobial resistance to humans.

INTRODUÇÃO: A atividade dos antimicrobianos em biofilmes depende do seu peso molecular, de cargas positivas, coeficiente de permeabilidade e atividade bactericida. Vancomicina é a escolha primária para o tratamento de infecções causadas por Staphylococcus aureus resistentes à meticilina (MRSA) e rifampicina possui interessante propriedade antibiofilme, apesar da sua efetividade ainda ser fracamente definida. MÉTODOS: Foi investigada a atividade da rifampicina sozinha e em combinação com vancomicina frente à MRSA formadores de biofilme, utilizando o método das microplacas com diluição seriada e recuperação bacteriana em biofilme após exposição antimicrobiana. RESULTADOS: Concentração inibitória minima (MIC) e concentração bactericida mínima (MBC) para vancomicina e rifampicina foi de 0,5-1mg/l e 0,008-4mg/l; 1-4mg/l e 0,06-32mg/l, respectivamente. Biofilmes maduros foram expostos à vancomicina e rifampicina, e a concentração mínima para erradicar o biofilme (MBEC) foi 64-32.000 e 32-512 vezes maior do que para células planctônicas, respectivamente. A combinação de vancomicina (15mg/l) com rifampicina (6-diluições maior do que o MIC de cada isolado) não atingiu erradicação do biofilme in vitro, porém apresentou capacidade inibitória do biofilme formado (redução de 1,43 e 0,56log10 UFC/ml para produtores fracos e fortes, respectivamente; p<0,05). CONCLUSÕES: Rifampicina sozinha falhou em efetivamente matar MRSA formadores de biofilme, demonstrando fraca habilidade para erradicação de biofilmes maduros comparado com vancomicina.

INTRODUCTION: Antimicrobial activity on biofilms depends on their molecular size, positive charges, permeability coefficient, and bactericidal activity. Vancomycin is the primary choice for methicillin-resistant Staphylococcus aureus (MRSA) infection treatment; rifampicin has interesting antibiofilm properties, but its effectivity remains poorly defined. METHODS: Rifampicin activity alone and in combination with vancomycin against biofilm-forming MRSA was investigated, using a twofold serial broth microtiter method, biofilm challenge, and bacterial count recovery. RESULTS: Minimal inhibitory concentration (MIC) and minimal bactericidal concentration for vancomycin and rifampicin ranged from 0.5 to 1mg/l and 0.008 to 4mg/l, and from 1 to 4mg/l and 0.06 to 32mg/l, respectively. Mature biofilms were submitted to rifampicin and vancomycin exposure, and minimum biofilm eradication concentration ranged from 64 to 32,000 folds and from 32 to 512 folds higher than those for planktonic cells, respectively. Vancomycin (15mg/l) in combination with rifampicin at 6 dilutions higher each isolate MIC did not reach in vitro biofilm eradication but showed biofilm inhibitory capacity (1.43 and 0.56log10 CFU/ml reduction for weak and strong biofilm producers, respectively; p<0.05). CONCLUSIONS: In our setting, rifampicin alone failed to effectively kill biofilm-forming MRSA, demonstrating stronger inability to eradicate mature biofilm compared with vancomycin.

INTRODUÇÃO: Vigilância com base em detecção laboratorial é um componente importante no controle de enterococos resistentes a vancomicina (ERV). MÉTODOS: Avaliamos procedimento da reação em cadeia da polimerase real time (PCR-RT) (genes vanA-vanB) para detecção de ERV em 115 swabs de pacientes incluídos em um programa de vigilância. RESULTADOS: A sensibilidade do RT-PCR foi semelhante a da cultura primária (75% e 79,5%, respectivamente) quando comparada com a cultura em caldo enriquecido, enquanto a especificidade foi de 83,1%. CONCLUSÕES: O RT-PCR fornece resultados no mesmo dia, contudo mostra baixa sensibilidade para a detecção de VRE.

INTRODUCTION: Laboratory-based surveillance is an important component in the control of vancomycin resistant enterococci (VRE). METHODS: The study aimed to evaluate real-time polymerase chain reaction (RT-PCR) (genes vanA-vanB) for VRE detection on 115 swabs from patients included in a surveillance program. RESULTS: Sensitivity of RT-PCR was similar to primary culture (75% and 79.5%, respectively) when compared to broth enriched culture, whereas specificity was 83.1%. CONCLUSIONS: RT-PCR provides same day results, however it showed low sensitivity for VRE detection.