Alexandre Rieger

Antibiotic resistance and detection of the sul2 gene in urinary isolates of Escherichia coli in patients from Brazil

INTRODUCTION The present study aimed to assess the antibiotic resistance profiles and detect the presence of the sul2 gene in sulfamethoxazole-susceptible and resistant isolates of Escherichia coli obtained from outpatients and inpatients with urinary tract infections. METHODOLOGY The resistance profiles of 739 strains were assessed and the presence of the sul2 gene in 100 isolates was tested. RESULTS The antibiotics with the highest resistance rates were ampicillin (57.4%) and trimethoprim-sulfamethoxazole (44.7%). The presence of the gene sul2 was detected in 66.7% of outpatient samples and 67.9% of inpatient samples. CONCLUSIONS Our results demonstrate that E. coli isolates exhibit high resistance to various classes of antibiotics, highlighting the need for developing strategies to help in prescribing antibiotics.

Prevalence of extended-spectrum beta-lactamases-producing microorganisms in nosocomial patients and molecular characterization of the shv type isolates

The emergence of Extended-Spectrum Beta-Lactamase (ESBL)-producing microorganisms in Brazilian hospitals is a challenge that concerns scientists, clinicians and healthcare institutions due to the serious risk they pose to confined patients. The goal of this study was the detection of ESBL production by clinical strains of Escherichia coli and Klebsiella sp. isolated from pus, urine and blood of patients at Hospital Universitário Santa Maria, Rio Grande Sul, RS, Brazil and the genotyping of the isolates based on bla SHV genes. The ESBL study was carried out using the Combined Disc Method, while Polymerase Chain Reaction (PCR) was used to study the bla SHV genes. Of the 90 tested isolates, 55 (61.1%) were identified as ESBL-producing by the combined disk method. The bla SHV genes were found in 67.8% of these microorganisms. K. pneumoniae predominated in the samples, presenting the highest frequency of positive results from the combined disk and PCR.

Prevalence of the TEM, SHV and CTX-M families of extended-spectrum β-lactamases in Escherichia coli and Klebsiella spp at the University Hospital of Santa Maria, State of Rio Grande do Sul

In this study, the distribution and prevalence of extended-spectrum beta-lactamases belonging to the TEM, SHV and CTX-M families were estimated among samples of Escherichia coli and Klebsiella spp. at the university hospital of Santa Maria, Rio Grande do Sul. Over a 14-month period, 90 microorganisms were selected as likely ESBL producers. The isolates were subjected to confirmatory phenotype tests for the presence of ESBL. Through investigating the respective genes using the polymerase chain reaction, the ESBL types present in each microorganism were then determined. Fifty-five samples (61.1%) were confirmed as ESBL-positive by means of the combined disc method, and 57 (63.3%) were found to be ESBL producers by means of the double disc method. From the polymerase chain reaction, ESBLs of TEM and SHV types were more frequently present in Klebsiella pneumoniae, while ESBL of CTX-M type was more frequently present in Klebsiella oxytoca.

EVALUATION OF FOUR DIFFERENT DNA EXTRACTION METHODS IN COAGULASE-NEGATIVE STAPHYLOCOCCI CLINICAL ISOLATES

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 its storage for a longer period of time. In this sense the extraction method based on an extraction column presented the best results for CoNS.

DNA damage and cytotoxicity in pathology laboratory technicians exposed to organic solvents

The aim of this study was to evaluate potential DNA damage and cytotoxicity in pathology laboratory technicians exposed to organic solvents, mainly xylene. Peripheral blood and buccal cells samples were collected from 18 technicians occupationally exposed to organic solvents and 11 non-exposed individuals. The technicians were sampled at two moments: Monday and Friday. DNA damage and cytotoxicity were evaluated using the Comet Assay and the Buccal Micronucleus Cytome assay. Fifteen subjects (83.5%) of the exposed group to solvents complained about some symptom probably related to contact with vapours of organic solvents. DNA damage in the exposed group to solvents was nearly 2-fold higher on Friday than on Monday, and in both moments the individuals of this group showed higher levels of DNA damage in relation to controls. No statistical difference was detected in buccal cell micronucleus frequency between the laboratory technicians and the control group. However, in the analysis performed on Friday, technicians presented higher frequency (about 3-fold) of karyolytic and apoptotic-like cells (karyorrhectic and pyknotic) in relation to control group. Considering the damage frequency and the working time, a positive correlation was found in the exposed group to solvents (r=0.468; p=0.05). The results suggest that pathology laboratory workers inappropriately exposed to organic solvents have increased levels of DNA damage.

Water Quality of Urban Streams: The Allium cepa Seeds/Seedlings Test as a Tool for Surface Water Monitoring

The present study investigates the genotoxic, mutagenic, and cytotoxic potential of surface waters in urban streams using Allium cepa and analyzes the applicability of this assay for environmental monitoring. Water samples were collected from three streams located in the urban area of a municipality in the south of Brazil. For each stream, two samples were collected, one upstream and one downstream of the pollution discharge site. Physicochemical evaluation indicated that all samples had various degrees of environmental impact, but substantial impact was seen for the downstream samples of the Preto and Pedras streams. All samples increased the frequency of chromosome aberrations (P < 0.05). The sample from Pedras downstream site also caused a decrease in mitotic index (P < 0.08) and increase in micronuclei (P < 0.08) frequency, indicating potential cytotoxicity and mutagenicity. The Pedras stream receives mixed industrial and urban wastewater, while the Lajeado and Preto streams receive wastewater predominantly domestic in nature, which may partially explain the difference in toxicity among the samples. Moreover, the Allium cepa seeds/seedlings were shown to be extremely sensitive in detecting the genotoxicity of environmental water samples and can be applied as the first tool for environmental health hazard identification and prediction.

Coagulase-negative staphylococci in southern brazil: Looking toward its high diversity

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.