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Biomedical subjects

L A Sechi

Publications and source records attributed to L A Sechi.

At least 19 recordsLinked to original sources
PubMed2005

Immunization with DNA vaccines encoding different mycobacterial antigens elicits a Th1 type immune response in lambs and protects against Mycobacterium avium subspecies paratuberculosis infection.

Paratuberculosis, or Johne's disease, is a disease of domestic and wild ruminants that culminate with a chronic enteritis caused by Mycobacterium avium subsp. paratuberculosis. The aim of this work was to evaluate the type of immune response, Th1 or Th2, induced by DNA vaccinations in lambs of Sarda breed. Twenty-five lambs, serum negative for M. paratuberculosis, were selected at birth from equally serum negative mothers. The lambs were inoculated at 5 months of age with three different mycobacterial antigens cloned into a mammalian expression vector as fusion protein with the enhanced green fluorescent protein (pEGFP-N1). The animals were divided in five groups containing each five lambs. Each group was vaccinated as following (A: physiological solution; B: Gudair; C: p-85A-Mav; D: p-85A-BCG; E: p-Hsp65). Immune response was evaluated by measuring the expression of INF-gamma (Th1 type response) and IL-10 (Th2 type response) by real-time PCR. Gene expression was estimated by comparing the results with that of beta-actin. INF-gamma expression level was increased in lambs vaccinated with plasmids codifying mycobacterial antigens, in particular with p-Hsp65, in comparison with the controls suggesting stimulation of a Th1 immune response similar to that supported by natural infection of M. paratuberculosis. Moreover, animals were infected orally with live M. paratuberculosis. Three months after vaccination and again INF-gamma and IL-10 expression was evaluated in order to verify in vivo the protection level of the vaccines. Plasmids p-85A-BCG and p-Hsp65 seem to elicit a stronger protective immune response against M. paratuberculosis by evaluating the expression level of INF-gamma and evaluating the presence of M. paratuberculosis and animal cell organ damage post-mortem.

Animals↗
PubMed2004

Mycobacterium avium sub. paratuberculosis in tissue samples of Crohn's disease patients.

Crohn's disease is a non-specific chronic transmural inflammatory disease. The disease was associated with a frameshit mutation in the NOD2 gene. Nevertheless, other researchers associated the presence of M. paratuberculosis within the intestinal tissues of patients with the disease. An adapted "in situ hybridization" technique was used to detect IS900 M. paratuberculosis DNA in paraffin embedded tissue from Crohns tissue disease samples. We were able to identify M. paratuberculosis DNA in around 69% of the paraffine embedded intestinal samples of Crohn's disease patients analysed. The presence of M. paratuberculosis DNA in the intestinal samples analysed does not necessarily mean that M. paratuberculosis is responsible for Crohn's disease. Our results support the hypothesis that infection may be caused by cell wall defective M. paratuberculosis since no bacteria were detected by Ziehl Neelsen stain.

Crohn Disease↗
PubMed2003

Comparison of the incidence of virulence determinants and antibiotic resistance between Enterococcus faecium strains of dairy, animal and clinical origin.

Enterococci are part of the dominant microbiota of several dairy products. They are also present in the gut of humans and animals. Their presence in traditional raw milk cheeses is probably due to faecal contamination of milk during milking. Due to their importance as a cause of nosocomial infections, enterococci are acquiring increased significance. Such infections are becoming more and more difficult to treat as resistance to antibiotics increases. The aim of this investigation was to compare the potential virulence of Enterococcus faecium isolated from different ecological habitats and to establish if strains isolated from dairy products should really be considered as potential pathogens. In the present work, the antibiotic resistance pattern of 40 E. faecium strains isolated from dairy products, 26 E. faecium isolated from ewes' faeces and 28 clinical isolates of the same species was studied, and checks were made to see if known virulence determinants were present. Resistance to 12 different antibiotics commonly used in the treatment of human infections was tested using the broth microdilution method as described by the NCCLS. In addition, polymerase chain reaction (PCR) tests were carried out to see if genes for vancomycin resistance were present. The presence of the aggregation substance (AS) gene, the surface protein gene esp, the accessory colonisation factor ace, the Enterococcus faecalis endocarditis antigen efaA and the gelatinase gelE gene, which are involved in the virulence of enterococci, were also tested by PCR. The results of this study clearly indicate that E. faecium strains isolated from both cheese and sheep faeces are less pathogenic than those isolated from clinical samples. A similar pattern of resistance to antibiotics was observed in both dairy and animal strains. It was also found that there was difference in the kind of virulence determinants present in dairy and clinical isolates, while no virulence traits were found in sheep faeces strains. The results of this study suggest that E. faecium from traditional Sardinian raw milk cheeses should not be considered to be the main source of untreatable nosocomial enterococcal infections in humans in the island of Sardinia.

Animals↗
PubMed2003

Incidence of virulence determinants in clinical Enterococcus faecium and Enterococcus faecalis isolates collected in Sardinia (Italy).

Enterococci are widely distributed in the environment; within the human body, they are normal commensals of the oral cavity, gastrointestinal tract and vagina. In recent years, enterococci have become one of the most frequent causes of acquired nosocomial infections worldwide. The molecular mechanism of virulence of these bacteria is still not completely understood. The aims of this work were to characterize phenotypically 47 isolates of Enterococcus faecalis and Enterococcus faecium collected in Sardinia (Italy) by their abilities to adhere to different epithelial cell lines (Vero and Caco-2 cells) and to associate their phenotypes with the presence of known virulence genes detected within their genomes by PCR. The following genes were amplified: AS (aggregation substance), esp (surface protein gene), ace (accessory colonization factor), efaA (E. faecalis endocarditis antigen) and gelE (gelatinase). The virulence genes were detected in E. faecalis isolates only, with the exception of esp, which was found in both species. The phenotypic and genotypic results were also compared with the susceptibility of isolates to various antibiotics.

Antigens, Bacterial↗
PubMed2003

A molecular method for the recovery and identification of enteric virus in shellfish.

In this paper we report the results of an investigation into the presence of enteric viruses in shellfish from the waters around Sardinia. Twenty two samples of shellfish were examined using a rapid and sensitive technique to concentrate and detect viral RNA in shellfish tissues. After recovery of viral particles, RNA was extracted, transcribed into cDNA and amplified using "nested PCR". Testing with enterovirus-specific RT-PCR produced positive results in over 13% of specimens. The virus detection procedure appears to be effective. In some circumstances it could be a better test of water quality than conventional monitoring techniques.

Bacteria↗
PubMed2002

Distribution of virulence genes in Aeromonas spp. isolated from Sardinian waters and from patients with diarrhoea.

AIMS: To characterize 46 isolates of different Aeromonas spp. strains (26 Aeromonas hydrophila, 13 Aeromonas sobria and 7 Aeromonas salmonicida) isolated from coastal water and clinical sources in Sardinia, Italy. METHODS AND RESULTS: The isolates were analysed for the production of the following virulence properties: slime, haemolysin, gelatinase and protease production, and adhesion to eucaryotic epithelial cells. The presence of known virulence genes: A. hydrophila cytolytic enterotoxin gene AHCYTOEN; type IV pilus gene Tap; Bundle forming pilus genes BfpA and BfpG were investigated using polymerase chain reaction (PCR). In addition the enterobacterial repetitive intergenic consensus sequences (ERIC)-PCR fingerprinting was used to further differentiate the strains. CONCLUSIONS: This study confirms the presence of virulent Aeromonas strains in the Mediterranean sea. The study also found a greater prevalence of haemolysin, protease and gelatinase production, as well as a higher adhesion capacity, among strains isolated from patients with diarrhoea. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first time that Aeromonads have been isolated and characterized from Sardinian waters and from patients with diarrhoea in Sardinia. This study adds to our knowledge of the ecology of this micro-organism and may in the future help prevent infections both in fish and in humans.

Aeromonas↗
PubMed2002

Virulence genes in halophilic Vibrio spp. isolated in common mussels.

Twenty-five Vibrio strains belonging to nine different species, isolated in common mussels, were examined for the presence of different virulence genes: ctxA, tcpA, toxR, toxS, ace, zot and vpi previously found in pathogenic Vibrio cholerae strains. Our results suggest that there is a wide dissemination of Vibrio cholerae virulence genes among the various Vibrio species tested. This finding raises the question of whether a different approach should be taken to study "environmental" Vibrio strains.

Animals↗
PubMed2002

Management of cardiovascular risk in diabetic patients: evolution or revolution?

Diabetes is associated with a marked increase in the risk of cardiovascular disease. Epidemiological evidence shows that hyperglycemia, hypertension and disorders of both lipid and thrombosis are involved in the etiology of cardiovascular disease in diabetes. Intervention trials on each of such factors have demonstrated a favourable effect in terms of reduction of cardiovascular disease, suggesting that even in diabetic patients in whom blood glucose levels are adequately controlled, other cardiovascular risk factors, such as hyperlipidemia, hypertension and prothrombotic state, should be aggressively treated. The need for an aggressive treatment has been recently underscored by the UKPDS (United Kingdom Prospective Diabetes Study) researchers who suggest that "polypharmacy" is now needed for the prevention of diabetic complications, implying that this approach requires an adequate control of all cardiovascular risk factors even using associations of drugs for each of them. A thorough application of these concepts might appear difficult in particular when the resource cost is considered. However, it has been shown that blood glucose, blood pressure and serum lipid control are advantageous in diabetic patients not only in terms of cost/benefit ratio but also in terms of quality of life. In the present article, we will briefly review this evidence and discuss the ethical and socioeconomic concerns that may subsequently rise.

Cardiovascular Diseases↗
PubMed2002

Strain variation in Mediterranean and Red Sea Mycobacterium marinum isolates.

Four different PCR fingerprinting techniques were tested to distinguish possible strain variations in fourteen Mycobacterium marinum isolates, thirteen from Mediterranean and Red Sea fishes and one from a patient in Sardinia, Italy. PCR ribotyping and ERIC (enterobacterial repetitive consensus sequences)-PCR were found to be non-discriminative, whereas IS (insertion sequences)-PCR and GTG (GTG sequences repeats)-PCR could distinguish the clinical isolate from the piscine isolates, two Italian piscine isolates from all other isolates, but not the Greek isolates from the Israeli isolates. Our results indicate that GTG-PCR and IS-PCR have superior discriminative properties and are thus useful molecular tools for epidemiological studies of M. marinum.

Animals↗
PubMed2001

Glycopeptide resistance among coagulase-negative staphylococci that cause bacteremia: epidemiological and clinical findings from a case-control study.

A 1-year prospective case-control study (ratio of control patients to case patients, 3:1) was performed to assess the incidence, risk factors, and genotypic patterns of bacteremia caused by glycopeptide-resistant coagulase-negative staphylococci (CoNS) and their correlation with hospital glycopeptide use. Among 535 subjects with CoNS bacteremia, 20 subjects had a glycopeptide-resistant strain (19 strains were resistant to teicoplanin and 1 was resistant to both teicoplanin and vancomycin). The percentage of resistant isolates recovered in 1 year was 8% in intensive care units and 3% and 2% in medical and surgical wards, respectively. Genotypic analysis of resistant strains showed different patterns with a high degree of polymorphism. Use of glycopeptides in individual wards was not statistically associated with the percentage of resistance. Previous exposure to beta-lactams and glycopeptides, multiple hospitalization in the previous year, and concomitant pneumonia were significantly associated with the onset of glycopeptide-resistant CoNS bacteremia. Mortality rates were 25% among case patients and 18% among control patients, and they were significantly higher among patients who presented with concomitant pneumonia and a high Acute Physiology and Chronic Health Evaluation III score.

Aged↗
PubMed2001

Bacillus cereus keratitis associated with contact lens wear.

OBJECTIVE: We report the first case of contact lens-related Bacillus cereus keratitis and ulcer associated with B. cereus contamination of the contact lens case. This is also the first study to investigate and establish the genetic identity of an organism isolated from the cornea and contact lens case in a patient with contact lens-associated keratitis. DESIGN: Case report. INTERVENTION AND TESTING: Conjunctival swabs and corneal scrapings from the left eye were inoculated for culture. The contact lens case was also cultured. Antibiotic susceptibility testing was determined by agar disk diffusion method. Initial treatment with topical ciprofloxacin and fortified tobramycin was given. Genetic analysis of the bacterial isolates was performed using polymerase chain reaction (PCR) with enterobacterial repetitive intergenic consensus primers (ERIC; ERIC-PCR). Susceptibility of B. cereus to heat and contact lens disinfecting solutions containing hydrogen peroxide, hydrogen peroxide-catalase, polyquaternium-1, and polyaminopropyl biguanide (PAPB) was tested. MAIN OUTCOME MEASURES: Clinical features, culture results, and antibiotic susceptibility testing were analyzed. The ERIC-PCR amplification products were visualized in ethidium bromide-stained agarose gel. Bacterial growth after exposure to heat and contact lens disinfecting solutions was assessed on blood agar plates. RESULTS: B. cereus was grown from the conjunctiva, corneal ulcer, and contact lens case. All isolates were sensitive to gentamicin, tobramycin, ciprofloxacin, clindamycin, and vancomycin. The corneal ulcer gradually healed over the next 6 days. Results of ERIC-PCR showed that the isolates from the cornea and contact lens case were indistinguishable, thus demonstrating the source of infecting organism to be the contaminated contact lens case. Exposure to a temperature of 80 degrees C for 20 minutes and incubation with hydrogen peroxide-catalase, polyquaternium-1, and PAPB for the minimum recommended time failed to kill B. cereus. Only exposure to hydrogen peroxide for 4 hours eradicated the organism. CONCLUSIONS: B. cereus should be considered a possible etiologic agent of contact lens-associated keratitis. Heat and many types of contact lens disinfecting solutions may be ineffective in eradicating B. cereus from contaminated contact lens cases. Only prolonged exposure to hydrogen peroxide appeared to be sporicidal to B. cereus in this study.

Bacillaceae Infections↗
PubMed2001

In vitro susceptibility of Vibrio spp. isolated from the environment.

Bacteria of the genus Vibrio include harmless aquatic strains as well as strains capable of causing epidemics of cholera and human intestinal diseases. Some of these species may show resistance to different antibiotics including cefotaxime, tetracycline and chloramphenicol. The susceptibility to different antibiotics was tested using 40 Vibrio alginolyticus, eight V. parahaemolyticus and six V. vulnificus strains isolated in the coastal waters of Northern Sardinia (Italy). The frequency of resistance to beta-lactams was unexpectedly high. More than 80% of Vibrio isolates were resistant to ampicillin and 2.5% of V. alginolyticus were resistant to ceftazidime and cefotetan. Forty percent of V. alginolyticus and three V. vulnificus isolates gave a positive nitrocefin test. PCR was also performed using selected primers chosen for having common sequences of bla(TEM) and bla(SHV) genes.

Anti-Bacterial Agents↗
PubMed2001

Antibacterial activity of ozonized sunflower oil (Oleozon).

AIMS: To evaluate the antimicrobial effect of the ozonized sunflower oil (Oleozon) on different bacterial species isolated from different sites. METHODS AND RESULTS: The effect of Oleozon on Mycobacteria, staphylococci, streptococci, enterococci, Pseudomonas and Escherichia coli was tested. The sunflower oil was ozonized at the Centro de Investigaciones del Ozone (CENIC, Havana, Cuba) by an ozone generator. MICs were determined by the agar dilution method. For Mycobacteria, the MIC of Oleozon was determined on solid medium by a microdrop agar proportion test. Oleozon showed antimicrobial activity against all strains analysed, with an MIC ranging from 1.18 to 9.5 mg ml-1. CONCLUSION: Oleozon showed a valuable antimicrobial activity against all micro-organisms tested. Results suggest that Mycobacteria are more susceptible to Oleozon than the other bacteria tested. SIGNIFICANCE AND IMPACT OF THE STUDY: The wide availability of sunflower oil makes Oleozon a competitive antimicrobial agent. These results should prompt the setting up of some clinical trials to compare Oleozon with other antimicrobial agents.

Bacteria↗
PubMed2001

Rapid identification of cutaneous infections by nontubercular mycobacteria by polymerase chain reaction-restriction analysis length polymorphism of the hsp65 gene.

BACKGROUND: Nontubercular mycobacteria (NTM) may cause cutaneous infections which are difficult to interpret due to the variability of the clinical manifestations. This study involved eight patients (four men and four women) with primary cutaneous infections caused by NTM; the skin lesions included dermo-hypodermal abscesses, suppurative granulomas, and papulonodules localized on the legs, arms, hands, and face. The general condition of the patients was relatively good and they were not immunosuppressed. METHODS: All samples were processed with standard methods and the isolates were identified by pattern restriction analysis after polymerase chain reaction (PCR-PCA) amplification of the heat shock protein of 65 kDa. RESULTS: In this way, we were able to identify three Mycobacterium chelonae strains, two Mycobacterium marinum, two Mycobacterium fortuitum, and one Mycobacterium avium. The lesions disappeared in 3 or 4 weeks after treatment with two or more antimicrobials. CONCLUSIONS: For a correct diagnosis of cutaneous infection by NTM, demonstrating the presence of mycobacteria is essential; routinely available techniques lack sensitivity and are extremely tedious; often mycobacteria are not seen after acid-fast stain. We used PCR-PCA to identify mycobacteria grown in liquid media; the time of identification of mycobacteria was shortened relative to conventional methods.

Adult↗