Rapid automated method for on-site determination of sulfadiazine in fish farming: a stainless steel veterinary syringe coated with a selective membrane of PVC serving as a potentiometric detector in a flow-injection-analysis system

Sulfadiazine is an antibiotic of the sulfonamide group and is used as a veterinary drug in fish farming. Monitoring it in the tanks is fundamental to control the applied doses and avoid environmental dissemination. Pursuing this goal, we included a novel potentiometric design in a flow-injection assembly. The electrode body was a stainless steel needle veterinary syringe of 0.8-mm inner diameter. A selective membrane of PVC acted as a sensory surface. Its composition, the length of the electrode, and other flow variables were optimized. The best performance was obtained for sensors of 1.5-cm length and a membrane composition of 33% PVC, 66% onitrophenyloctyl ether, 1% ion exchanger, and a small amount of a cationic additive. It exhibited Nernstian slopes of 61.0 mV decade-1 down to 1.0×10-5 mol L-1, with a limit of detection of 3.1×10-6 mol L-1 in flowing media. All necessary pH/ionic strength adjustments were performed online by merging the sample plug with a buffer carrier of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, pH 4.9. The sensor exhibited the advantages of a fast response time (less than 15 s), long operational lifetime (60 days), and good selectivity for chloride, nitrite, acetate, tartrate, citrate, and ascorbate. The flow setup was successfully applied to the analysis of aquaculture waters. The analytical results were validated against those obtained with liquid chromatography–tandem mass spectrometry procedures. The sampling rate was about 84 samples per hour and recoveries ranged from 95.9 to 106.9%.

Selective recognition in potentiometric transduction of amoxicillin by molecularly imprinted materials

The indiscriminate use of antibiotics in food-producing animals has received increasing attention as a contributory factor in the international emergence of antibiotic-resistant bacteria (Woodward in Pesticide, veterinary and other residues in food, CRC Press, Boca Raton, 2004). Numerous analytical methods for quantifying antibacterial residues in edible animal products have been developed over years (Woodward in Pesticide, veterinary and other residues in food, CRC Press, Boca Raton, 2004; Botsoglou and Fletouris in Handbook of food analysis, residues and other food component analysis, Marcel Dekker, Ghent, 2004). Being Amoxicillin (AMOX) one of those critical veterinary drugs, efforts have been made to develop simple and expeditious methods for its control in food samples. In literature, only one AMOX-selective electrode has been reported so far. In that work, phosphotungstate:amoxycillinium ion exchanger was used as electroactive material (Shoukry et al. in Electroanalysis 6:914–917, 1994). Designing new materials based on molecularly imprinted polymers (MIPs) which are complementary to the size and charge of AMOX could lead to very selective interactions, thus enhancing the selectivity of the sensing unit. AMOX-selective electrodes used imprinted polymers as electroactive materials having AMOX as target molecule to design a biomimetic imprinted cavity. Poly(vinyl chloride), sensors of methacrylic acid displayed Nernstian slopes (60.7 mV/decade) and low detection limits (2.9 × 10−5 mol/L). The potentiometric responses were not affected by pH within 4–5 and showed good selectivity. The electrodes were applied successfully to the analysis of real samples.

Functional studies on BolA and related genes: increasing the understanding of a protein with pleiotropic effects

Dissertation presented to obtain a Doctoral degree in Biology by Instituto de Tecnologia Química e Biológica

Infective Endocarditis Complicated by Large Aortic Pseudoaneurysm after Cardiac Surgery

A 66-year-old female with Streptococcus viridans aortic and tricuspid infective endocarditis develops, during the course of antibiotic therapy, rupture of a right coronary sinus of Valsalva aneurysm to the right ventricle. An urgent cardiac surgery is preformed with implantation of a mechanical aortic prosthesis and a right coronary sinus plasty. Six months later a huge aortic pseudoaneurysm is diagnosed and she is submitted to a second uneventful surgery. A review is done for the significant features with discussion of diagnosis and therapy.

Echinococcosis in southern Brazil: efforts toward implementation of a control program in Santana do Livramento, Rio Grande do Sul

This investigation aimed to design a strategy for echinococcosis control in Santana do Livramento county, an endemic area in state of Rio Grande do Sul (Brazil). Fecal samples from 65 dogs were obtained from urban, suburban and rural areas. Purging with Arecoline Bromhidrate (AB) was done to visualize Echinococcus granulosus, and Enzyme Linked Immunosorbent Assay (ELISA) was performed to detect parasite coproantigen. Samples were obtained at the beginning and at the end of treatment with Praziquantel. A third fecal sampling was also done in rural areas four months after the end of treatment. Each dog was treated immediately after the first purging and every 30 days for eight months. In urban and suburban areas no infected dogs were found. In rural areas, first evaluation showed 11.36% and 27.69% of infected dogs by AB and ELISA, respectively. No infected dogs were diagnosed in the second evaluation and in the third evaluation 36.84% and 47.37% infected dogs were identified by AB and ELISA, respectively. Medication program to combat dog infection resulted in successful interruption of parasite transmission, but the project failed to create awareness of the need for dog prophylaxis among rural populations as well as to establish a permanent control program in this municipality.

Mycophenolate mofetil may protect against Pneumocystis carinii pneumonia in renal transplanted patients

Pneumocystis carinii pneumonia (PCP) is usually prevented in transplanted patients by prophylactic trimethoprim-sulfamethoxazol (TMS). Mycophenolate mofetil (MMF) has been shown to have a strong protective effect against PCP in rats. This effect is also suggested in humans by the absence of PCP in patients receiving MMF. After January 1998 MMF has been used with no TMS prophylaxis in renal transplanted patients. In azathioprine (AZA) treated patients TMS prophylaxis was maintained. The incidence of PCP was analyzed in both groups. Data were collected in order to have a minimum 6-month follow-up. Two hundred and seventy-two patients were eligible for analysis. No PCP occurred either in patients under MMF without TMS prophylaxis nor in patients under AZA. MMF may have an effective protective role against PCP as no patient under MMF, despite not receiving TMS coverage, developed PCP. A larger, controlled, trial is warranted to consolidate this information.

Clinical guideline for diagnosis and management of melioidosis

Melioidosis is an emerging infection in Brazil and neighbouring South American countries. The wide range of clinical presentations include severe community-acquired pneumonia, septicaemia, central nervous system infection and less severe soft tissue infection. Diagnosis depends heavily on the clinical microbiology laboratory for culture. Burkholderia pseudomallei, the bacterial cause of melioidosis, is easily cultured from blood, sputum and other clinical samples. However, B. pseudomallei can be difficult to identify reliably, and can be confused with closely related bacteria, some of which may be dismissed as insignificant culture contaminants. Serological tests can help to support a diagnosis of melioidosis, but by themselves do not provide a definitive diagnosis. The use of a laboratory discovery pathway can help reduce the risk of missing atypical B. pseudomallei isolates. Recommended antibiotic treatment for severe infection is either intravenous Ceftazidime or Meropenem for several weeks, followed by up to 20 weeks oral treatment with a combination of trimethoprim-sulphamethoxazole and doxycycline. Consistent use of diagnostic microbiology to confirm the diagnosis, and rigorous treatment of severe infection with the correct antibiotics in two stages; acute and eradication, will contribute to a reduction in mortality from melioidosis.

Candidemia in a Brazilian hospital: the importance of Candida parapsilosis

The aim of this study was to perform a retrospective analysis of cases of candidemia in a Brazilian hospital in the city of Fortaleza, Ceará. A total of 50 blood cultures were analyzed from 40 candidemic patients. The mycological diagnosis was based on the phenotypical analysis and the patients' data were recorded in appropriate files. The most frequent species were Candida parapsilosis (n = 18), followed by C. albicans (n = 14), C. tropicalis (n = 8), C. guillermondii (n = 6), C. glabrata (n = 2), and Candida spp. (n = 2). A detailed descriptive study was undertaken with 21 patients whose medical records were complete. The candidemia episodes occurred in eight male patients and 13 female patients. The most representative risk factors implicated in candidemia were prior antibiotic therapy, central venous catheters, parenteral nutrition, gastric probes and mechanical ventilation. Death occurred in 13 of the 21-candidemic patients. This study demonstrated the emergence of candidemia caused by C. parapsilosis in a Brazilian hospital in the city of Fortaleza, Ceará.

Listeria monocytogenes peritonitis in cirrhotic patients: first description in Brazil

Two cases of spontaneous bacterial peritonitis (SBP) caused by Listeria monocytogenes in cirrhotic patients are reported. In one of the cases, the microorganism was isolated from pleural effusion and ascites. SBP is a serious and common complication of patients with ascites caused by hepatic cirrhosis and the culture of the ascitic fluid is an important tool for the diagnosis and for the more appropriate treatment. Although a third generation cephalosporin has usually been employed for empiric treatment of SBP, it does not provide adequate coverage against Listeria spp. In such cases the use of ampicillin (with or without sulbactam) or sulfamethoxazole-trimethoprim is recommended. The last one is used for secondary prophylaxis, instead of norfloxacin. To summarize, Listeria monocytogenes infection is a rare cause of SBP, whose treatment should be specific for the bacteria.

Rhinoscleroma: eight Peruvian cases

Rhinoscleroma is a rare infection in developed countries; although, it is reported with some frequency in poorer regions such as Central Africa, Central and South America, Eastern and Central Europe, Middle East, India and Indonesia. Nowadays, rhinoscleroma may be erroneously diagnosed as mucocutaneos leishmaniasis, leprosy, paracoccidioidomycosis, rhinosporidiasis, late syphilis, neoplasic diseases or other upper airway diseases. From 1996 to 2003, we diagnosed rhinoscleroma in eight patients attended in the Dermatologic and Transmitted Diseases service of "Cayetano Heredia" National Hospital, in Lima, Peru. The patients presented airway structural alterations producing nasopharyngeal, oropharyngeal and, in one patient, laryngeal stenosis. Biopsy samples revealed large vacuolated macrophages (Mikulicz cells) in all patients. Ciprofloxacin 500 mg bid for four to 12 weeks was used in seven patients and oxytetracycline 500 mg qid for six weeks in one patient. After follow-up for six to 12 months the patients did not show active infection or relapse, however, all of them presented some degree of upper airway stenosis. These cases are reported because of the difficulty diagnosing the disease and the success of antibiotic treatment.

The "in vitro" antifungal activity evaluation of propolis G12 ethanol extract on Cryptococcus neoformans

Cryptococcosis is a worldwide disease caused by the etiological agent Cryptococcus neoformans. It affects mainly immunocompromised humans. It is relatively rare in animals only affecting those that have received prolonged antibiotic therapy. The propolis is a resin that can present several biological properties, including antibacterial, antifungal and antiviral activities. The standard strain C. neoformans ATTC 90112 was used to the antifungal evaluation. The tests were realized with propolis ethanol extract (PEE) G12 in concentrations from 0.1 to 1.6 mg mL-1. The evaluation of MIC and MFC were done according to DUARTE (2002)5. The inhibitory effect of PEE G12 on the fungal growing was seen at the concentration of 0.2 mg mL-1 and 1.6 mg mL-1 was considered a fungicidal one.

Diabetic Foot Infections: Current Diagnosis and Treatment

Diabetes mellitus (DM) is a global epidemic, and diabetic foot ulcer (DFU) is one of its most serious and costly complications. DFUs result from a complex interaction of a number of risk factors. Once the protective layer of skin is broken, deep tissues are exposed to bacterial infection that progresses rapidly. Patients with DFUs frequently require amputations of the lower limbs and, in more than half the cases, infection is the preponderant factor. Given the challenges of treating these complex infections, this paper aims to provide a hospital-based framework for the diagnosis and treatment of diabetic foot infections (DFIs). We propose a treatment-oriented assessment of DFIs based on a cross-examination of the medical, foot, and wound history; a systemized and detailed physical examination; and the results of complementary diagnostic procedures. We stress the need for a clinical diagnosis of DFIs and the importance of microbiological evaluation for antibiotic therapy guidance. Regarding treatment, we propose a multidisciplinary approach prioritizing invasive infection drainage, necrosis debridement, and the prompt start of empirical antibiotic therapy, followed by complete and appropriate vascular reconstruction. For severe DFIs, we suggest that negative pressure wound therapy (NPWT) be included in the treatment pathway. We also provide rules for managing particular situations, such as osteomyelitis. It is our hope that this protocol will improve the hospital management of DFIs and, ultimately, the prognosis of DFI patients.

Heparinized nanohydroxyapatite/collagen granules for controlled release of vancomycin

The purpose of this study was to develop a bone substitute material capable of preventing or treating osteomyelitis through a sustainable release of vancomycin and simultaneously inducing bone regeneration. Porous heparinized nanohydroxyapatite (nanoHA)/collagen granules were characterized using scanning electron microscopy, micro-computed tomography and attenuated total reflectance Fourier transform infrared spectroscopy. After vancomycin adsorption onto the granules, its releasing profile was studied by UV molecular absorption spectroscopy. The heparinized granules presented a more sustainable release over time, in comparison with nonheparinized nanoHA and nanoHA/collagen granules. Vancomycin was released for 360 h and proved to be bioactive until 216 h. Staphylococcus aureus adhesion was higher on granules containing collagen, guiding the bacteria to the material with antibiotic, improving their eradication. Moreover, cytotoxicity of the released vancomycin was assessed using osteoblast cultures, and after 14 days of culture in the presence of vancomycin, cells were able to remain viable, increasing their metabolic activity and colonizing the granules, as observed by scanning electron microscopy and confocal laser scanning microscopy. These findings suggest that heparinized nanoHA/collagen granules are a promising material to improve the treatment of osteomyelitis, as they are capable of releasing vancomycin, eliminating the bacteria, and presented morphological and chemical characteristics to induce bone regeneration.

Occurrence of Proteus mirabilis associated with two species of venezuelan oysters

The fecal contamination of raw seafood by indicators and opportunistic pathogenic microorganisms represents a public health concern. The objective of this study was to investigate the presence of enteric bacteria colonizing oysters collected from a Venezuelan touristic area. Oyster samples were collected at the northwestern coast of Venezuela and local salinity, pH, temperature, and dissolved oxygen of seawater were recorded. Total and fecal coliforms were measured for the assessment of the microbiological quality of water and oysters, using the Multiple Tube Fermentation technique. Analyses were made using cultures and 16S rRNA gene sequencing. Diverse enrichment and selective culture methods were used to isolate enteric bacteria. We obtained pure cultures of Gram-negative straight rods with fimbriae from Isognomon alatus and Crassostrea rhizophorae. Our results show that P. mirabilis was predominant under our culture conditions. We confirmed the identity of the cultures by biochemical tests, 16S rRNA gene sequencing, and data analysis. Other enterobacteria such as Escherichia coli, Morganella morganii and Klebsiella pneumoniae were also isolated from seawater and oysters. The presence of pathogenic bacteria in oysters could have serious epidemiological implications and a potential human health risk associated with consumption of raw seafood.