Lenise Arneiro Teixeira

The Predominant Variant of the Brazilian Epidemic Clonal Complex of Methicillin-Resistant Staphylococcus aureus Has an Enhanced Ability to Produce Biofilm and to Adhere to and Invade Airway Epithelial Cells

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a therapeutic problem. In the present study, the molecular characterization by pulsed-field gel electrophoresis of MRSA isolates collected from a university hospital revealed that the predominant variant of the Brazilian epidemic clonal complex (BECC) was responsible for the increase in the incidence of MRSA strains, which reached 28% in 1998. It was verified that this predominant variant of the BECC displayed an enhanced ability to produce biofilm on inert polystyrene surfaces and to adhere to and invade epithelial airway cells. These results indicate that MRSA strains belonging to the BECC have evolved advantageous properties that might play a role in their predominance as international nosocomial pathogens.

Spread of the Brazilian epidemic clone of a multiresistant MRSA in two cities in Argentina.

Methicillin-resistant Staphylococcus aureus (MRSA) is recognised as an important cause of nosocomial infection. The spread of some MRSA epidemic clones is well documented. In Brazil, and more recently in Portugal, a considerable number of hospital infections has been caused by a unique multiresistant MRSA clone designated as the Brazilian epidemic clone. This paper describes the spread of this clone in hospitals in two cities in Argentina.

Isolation of methicillin-resistant coagulase-negative staphylococci from patients undergoing continuous ambulatory peritoneal dialysis (CAPD) and comparison of different molecular techniques for discriminating isolates of Staphylococcus epidermidis

Coagulase-negative staphylococci (CNS) have emerged as an important pathogen in nosocomial infections. About 80%-90% of CNS isolates associated with hospital infections are methicillin-resistant coagulase-negative staphylococci (MRCNS). The aims of this study were to screen for MRCNS isolates in the flora of a small population of patients undergoing continuous ambulatory peritoneal dialysis (CAPD) and to evaluate the discriminatory power of different molecular methods: pulsed-field gel electrophoresis (PFGE), mecA location, ClaI/mecA polymorphism and arbitrarily primed polymerase chain reaction (AP-PCR) for characterizing isolates of methicillin-resistant Staphylococcus epidermidis (MRSE). Seventy-nine CNS isolates were recovered from the 11 CAPD patients studied. Using a methicillin screening agar and a DNA specific mecA probe we verified that 30 of the 79 (38%) CNS isolates were resistant to methicillin (MRCNS). Twenty-two of the 30 MRCNS (73%) were MRSE, 7 (23%) methicillin-resistant S. haemolyticus (MRSH(ae)) and 1 (3%) methicillin-resistant S. hominis (MRSH(om)). All patients analyzed carried MRCNS in their flora, in one or more sites. Since CAPD patients have high risk for developing peritonitis, the colonization of these patients with MRCNS might represent an additional problem, due to the therapeutic restrictions imposed by these multiresistant isolates. A wide genetic diversity was verified when the PFGE of the MRSE isolates was analyzed. The 22 MRSE isolates displayed a total of 15 PFGE different patterns (11 PFGE types and 4 subtypes). The location of mecA in the SmaI-fragmented genome DNA did not bring any additional advantage for epidemiologic characterization of the isolates. The ClaI/mecA polymorphism was able to correctly discriminate 12 from the 15 PFGE patterns. In addition, the DNA of 20 MRSE isolates were used for AP-PCR typing. These isolates belonged to 14 PFGE patterns (11 types and 3 subtypes) and displayed 15 genotypes (for the association of PFGE, mecA location and ClaI/mecA polymorphism). A total of 17 different amplification patterns was verified using the primer 1. Only for 2 genotypes, strains having identical genetic backgrounds were further discriminated by AP-PCR (2 of 15 genotypes (87%) for AP-PCR and 1 of 15 genotypes for PFGE; (93%). Concluding, our results indicated that the AP-PCR can be an alternative and useful tool for monitoring and genotyping MRSE colonization and also to molecular characterizing MRSE outbreaks in hospitals.

Emergence of multiresistant variants of the community-acquired methicillin-resistant Staphylococcus aureus lineage ST1-SCCmecIV in 2 hospitals in Rio de Janeiro, Brazil.

Usually, community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is susceptible to a variety of non-beta-lactam drugs. These isolates commonly display SCCmecIV and are associated with community-acquired infections. More recently, CA-MRSA has been isolated from health-care-associated diseases. We characterized MRSA isolates from 2 hospitals in Rio de Janeiro area to assess the entry of new lineages. The isolates were primary genotyped using a combination of molecular typing methods including SCCmec, restriction modification test, and Panton-Valentine leukocidin (PVL) detection. Pulsed-field gel electrophoresis was carried out for representatives of each lineages found. Disk diffusion test was performed as recommended by the Clinical and Laboratory Standards Institute. SCCmecIV was the predominant cassette mec detected. The most frequent MRSA lineage, a PVL nonproducer, was allocated in the CC1-SCCmecIV. It was found that 56% of these isolates were resistant to 3 or more non-beta-lactam drugs. Multilocus sequence typing of a representative of the CC1 isolates supported our finds that multiresistant variants of a CA-MRSA lineage (ST1-SCCmecIV) emerged in this city.

Chemical composition and antibacterial activity of Brazilian propolis essential oil

The present study aimed at investigating the chemical composition of essential oil extracted from Brazilian propolis and the susceptibility of Staphylococcus aureus, Staphylococcus epidermides, Streptococcus pyogenes and Escherichia coli to this substance. The essential oil was obtained by steam distillation of propolis and examined by gas chromatography/mass spectrometry (GC/MS). In addition, the agar diffusion method using filter paper disks was employed. Antibacterial activity was measured as equivalent diameters of inhibition zones (in millimeters) after incubation at 37o C for 24 hours. From the 26 identified constituents, β-caryophyllene (12.7%), acetophenone (12.3%) and β-farnesene (9.2%) were found to be major components. New components, namely linalool, methyl hydrocinnamate, ethyl hydrocinnamate, α-ylangene, γ-elemene and valencene, are reported for the first time to be present in propolis essential oil. This oil also exhibited antibacterial activity.

Atividade antibacteriana de floroglucinóis e do extrato hexânico de Hypericum brasiliense Choysi

Three phloroglucinols were obtained from Hypericum brasiliense: japonicine A (1), isouliginosin B (2) and uliginosin B (3). Bioautography and disk diffusion methods were used to determine antibacterial activity of the hexanic extract. Strains of the Coagulase Negative Staphylococcus and American Methicillin Resistant Staphylococcus aureus clones showed a growth inhibition zone ranging from 10 to 12 mm and 7 to 15 mm, respectively. Minimal inhibitory concentration (MIC) values were used to measure antistaphylococcal activity for all phloroglucinols. Isouliginosin B and uliginosin B presented MIC values of 1.5 and 3.0 µg/mL, respectively, while japonicine A displayed MIC value of 50.0 µg/mL.

Avaliação da atividade IMAO e antibacteriana de extratos de Mikania glomerata Sprengel

Antibacterial and IMAO inhibition activities of different polarities extracts of Mikania glomerata were evaluated. The antibacterial activity was assayed against a multiresistant strain of Staphyllococus aureus PI57. The IMAO activity was measured with a suspension of mitochondrion. In the hexanic extract of Mikania glomerata substances with antibacterial activity were detected. Hexanic and CH2Cl2 extracts showed MAO-B inhibition activity while MAO-A inhibition activity was not detected. The methanolic extract showed non-selective inhibition activity of MAO-A and MAO-B.

Prevalence, aetiology and antibiotic resistance profiles of coagulase negative staphylococci isolated in a teaching hospital

In this paper we carried out a study about prevalence of the clinically significant coagulase negative staphylococcal (CNS) isolates found in an university hospital. Two hundred four CNS isolates from 191 patients obtained between the period of 1998 to 2002, were studied. About 27% (52/191) of the infection cases studied were confirmed as CNS-associated diseases. Blood stream infection (BSI) was the most frequent CNS associated-disease (25%; 13/52). The great majority of the BSI was verified in the Neonatal Intensive Care Unit (NICU). The analysis of the 52 patients medical history showed that 85% of the BSI was acquired in hospital. Most of the CNS nosocomial infections were associated with the use of indwelling medical devices. The incidence of methicillin-resistance among significant CNS isolates was 38%. In this study, a high percentage of exogenous contaminant was verified (60%), indicating that contamination of clinical specimens during sample collection is critical.

The antimicrobial susceptibility, biofilm formation and genotypic profiles of Staphylococcus haemolyticus from bloodstream infections

We analysed the antimicrobial susceptibility, biofilm formation and genotypic profiles of 27 isolates of Staphylococcus haemolyticus obtained from the blood of 19 patients admitted to a hospital in Rio de Janeiro, Brazil. Our analysis revealed a clinical significance of 36.8% and a multi-resistance rate of 92.6% among these isolates. All but one isolate carried the mecA gene. The staphylococcal cassette chromosome mec type I was the most prevalent mec element detected (67%). Nevertheless, the isolates showed clonal diversity based on pulsed-field gel electrophoresis analysis. The ability to form biofilms was detected in 66% of the isolates studied. Surprisingly, no icaAD genes were found among the biofilm-producing isolates.

Biofilm formation and prevalence of lukF-pv, seb, sec and tst genes among hospital- and community-acquired isolates of some international methicillin-resistant Staphylococcus aureus lineages

Methicillin-resistant Staphylococcus aureus (MRSA) is an important nosocomial agent of biopolymer-associated infections, and isolates of S. aureus can produce different virulence factors, including potent toxins. The biofilm formation and accumulation by certain international MRSA lineages were analysed, and the toxic shock syndrome-associated genes (tst, seb and sec) among these isolates were assessed. In addition, the presence of lukF-pv (encoding the F-subunit of Panton-Valentine leukocidin (PVL)) was investigated. Most of the MRSA isolates tested were capable of forming biofilm on polystyrene surfaces, but lacked the superantigen toxin genes that were tested. PVL was rarely detected among the hospital isolates analysed.