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Biomedical subjects

Y Tselentis

Publications and source records attributed to Y Tselentis.

At least 55 records · Page 3Linked to original sources
PubMed1997

Bacterial pathogens associated with diarrhoea on the island of Crete.

Stool specimens from 3,600 diarrhoeal patients from the island of Crete, Greece, were examined for bacterial pathogens, during a three-year period (1992-1994). One or more pathogens were identified in 826 patients (22.9%), more often from children. Salmonella spp. were the most frequently isolated organisms in 13.6% of the patients, followed by Campylobacter in 4.7%, and enteropathogenic Escherichia coli (EPEC) in 3.9%. Yersinia enterocolitica was found in 0.7%, Shigella spp. in 0.7% and Aeromonas hydrophila in 0.05%. Vibrio spp. and enterohaemorragic E. coli were not identified in the stools tested. Resistance to ampicillin was observed in 36% of the Salmonella, 62% of the Shigella, and 27% of the EPEC isolates. Cotrimoxazole resistance was observed in 42% of the Shigella and 12% of the EPEC isolates, while tetracycline and the quinolones were inactive against almost half and erythromycin against 20% of the Campylobacter isolates. This is the first study investigating bacterial pathogens associated with diarrhoea on the island of Crete.

Adolescent↗
PubMed1997

A focus of Fasciola hepatica in Crete without human cases.

In Greece, Fasciola hepatica, the sheep liver fluke, is common in sheep but only three human cases of fascioliasis have been reported. An epidemiological study was conducted in central Crete which proved to be a focus of F. hepatica. Sheep and snails were found positive for this parasite, but none of the 205 persons tested serologically.

Animals↗
PubMed1997

Effect of norfloxacin, trimethoprim-sulfamethoxazole and nitrofurantoin on fecal flora of women with recurrent urinary tract infections.

The effects of antibiotics used for prophylaxis in women with recurrent urinary tract infections (UTIs) on the aerobic intestinal flora were investigated. Twenty-one patients with recurrent UTIs were randomly divided into three groups. The patients of each group received monotherapy with oral norfloxacin, trimethoprim-sulfamethoxazole or nitrofurantoin for one month. Urine and stool quantitative aerobic cultures were performed before prophylaxis, 2 and 4 weeks after the initiation of therapy, and 2 weeks after antibiotics were discontinued. The gram-negative aerobic flora was strongly suppressed during the administration of norfloxacin and trimethoprim-sulfamethoxazole, while Enterococcus spp. were not affected. Resistant strains of Escherichia coli were detected in two patients, one in the norfloxacin and one in the trimethoprim-sulfamethoxazole group. The aerobic intestinal flora was not affected by nitrofurantoin. These findings help in the selection of the most appropriate antimicrobial agent for prophylaxis in recurrent UTIs, so as to reduce the possibility of emergence of resistant bacterial strains.

Adult↗
PubMed1996

Detection of ciprofloxacin resistance mutations in Campylobacter jejuni gyrA by nonradioisotopic single-strand conformation polymorphism and direct DNA sequencing.

A total of 27 strains of Campylobacter jejuni (24 clinical strains and three laboratory strains) were examined for the presence of point mutations in the quinolone resistance determining region (QRDR) of gyrA gene by nonradioisotopic single-strand conformation polymorphism (non-RI SSCP) analysis with silver stain. Direct DNA sequencing of the polymerase chain reaction (PCR)-amplified DNA fragments confirmed the results obtained by non-RI SSCP analysis and revealed that in clinical strains high-level quinolone resistance [minimal inhibitory concentration (MIC) to ciprofloxacin > or = 16 micrograms/ml] was closely associated with one type of single-point mutation at codon 86 (Thr-Ile). Two strains with MICs of 8 and 1 microgram/ml showed point mutations at codons 86 and 70, respectively. Furthermore, transitions at codon 119 of the gyrA QRDR were identified in 17 strains. Six types of bands were separated in a single electrophoretic step with silver stain within 2 hours after PCR amplification of the gyrA QRDR as follows: type I associated to mutation at codon 70 (Ala-Thr), type II to mutation at codon 90 (Asp-Asn), type III to variant with transition at 119, type IV to wild-type, type V to mutation at codon 86 (Thr-Ile), and type VI to mutation at codon 86 (Thr-Ile) and transition at codon 119. Using four DNA extracts from Cambylobacter coli organisms as templates for amplification of the gyrA QRDR, no PCR products were obtained. Non-RI SSCP was proved to be a simple, rapid, and useful screening method for detecting gyrA mutations associated with ciprofloxacin resistance in C. jejuni.

Anti-Infective Agents↗
PubMed1996

Water wells as a habitat of sand fly (Diptera: Psychodidae) vectors of visceral leishmaniasis in Greece.

Overall, 37 of 79 water wells in 3 diverse geographic areas of Greece were found to harbor sand flies. The predominant species were Phlebotomus tobbi Adler, Theodor & Lourie and P. neglectus Tonnoir, species implicated in the transmission of Leishmania infantum Nicolle. Three additional species of Phlebotomus and 2 Sergentomyia spp. also encountered. Wells appear to be resting and possibly breeding habitat for sand flies in Greece.

Animals↗
PubMed1996

Canine visceral leishmaniasis: successful chemotherapy induces macrophage antileishmanial activity via the L-arginine nitric oxide pathway.

Following successful chemotherapy in canine visceral leishmaniasis, monocyte-derived macrophages can induce antileishmanial activity via a gamma interferon-dependent mechanism in the presence of autologous lymphocytes. The killing of leishmania correlated with the induction of the NO synthase pathway, because it correlated with the generation of nitrogen derivative production and was abrogated in the presence of NG-monomethyl-L-arginine, a competitive inhibitor of the NO synthase pathway. The level of L-citrulline in serum, which was produced after activation of the NO synthase pathway, was markedly enhanced in dogs receiving successful chemotherapy. Taken together, these data indicate that following successful chemotherapy of visceral leishmaniasis, leishmania parasites are killed by macrophages activated by gamma interferon-producing lymphocytes via an NO-dependent mechanism.

Animals↗
PubMed1996

Effects of cyclophosphamide and ceftriaxone on gastrointestinal colonization of mice by Candida albicans.

Adult male Crl:CD1 (ICR) mice were fed chow containing Candida albicans to induce sustained gastrointestinal colonization by the yeast. Groups of mice were rendered neutropenic with cyclophosphamide and subsequently received ceftriaxone, while other groups received normal saline and served as controls. Stool cultures were obtained immediately before and at the end of treatment. The administration of cyclophosphamide substantially increased the C. albicans counts in the stools of mice. The addition of ceftriaxone to the cyclophosphamide regimen did not significantly increase the level of gastrointestinal colonization by C. albicans. There was no evidence of Candida dissemination to internal organs.

Alkylating Agents↗
PubMed1996

Genotypic identification of murine typhus Rickettsia in rats and their fleas in an endemic area of Greece by the polymerase chain reaction and restriction fragment length polymorphism.

Forty-nine cases of murine typhus were diagnosed in recent years in residents of several communities around the city of Chalkis, the capital of the Prefecture of Evia. (Euboea) Evia is an island connected to central mainland Greece by a bridge. To investigate the endemicity of murine typhus in this area, 226 fleas (Xenopsylla cheopis) and blood samples were collected from 53 rats (Rattus norvegicus) trapped in this area. The polymerase chain reaction followed by restriction fragment length polymorphism analysis (PCR-RFLP) was used to detect and identify Rickettsia typhi, the etiologic agent murine typhus, in the rat blood samples (buffy coat cells) as well as in their fleas. An indirect immunofluorescent antibody (IFA) assay was performed to detect antibodies against R. typhi in rat serum samples. The presence of R. typhi in both fleas and rat blood samples was demonstrated. The frequency of infection for X. cheopis was 4%, while 18% of the rats had buffy coat cells infected, and 92% of the rat sera tested by IFA were positive for anti-R. typhi antibodies. The present work is the first successful application of PCR-RFLP in a field study of naturally infected rats and their fleas in Europe.

Animals↗
PubMed1995

The seroprevalence of ten zoonoses in two villages of Crete, Greece.

The seroprevalence and incidence of 10 zoonoses due to Rickettsia typhi, R. conorii, Coxiella burnetii, Burcella sp., Borrelia sp., Toxoplasma sp., Leishmania sp., Entamoeba histolytica, Echinococcus granulosus and Fasciola hepatica were studied in an animal husbandry and a farming village in Crete, Greece. The serum conversion incidence of each infectious agent was determined by testing 2 blood samples, collected in 1985 and in 1987. The surveillance was conducted using detailed transparent maps of the 2 villages studied, on which epidemiological data were interrelated to the results obtained from the serological tests. Thus the importance and spread of each infection were visualized. C. burnetii, Toxoplasma sp., R. conorii, and E. granulosus, were the most common infectious agents encountered during this study.

Adult↗
PubMed1995

Q fever in the Greek Island of Crete: epidemiologic, clinical, and therapeutic data from 98 cases.

A retrospective study was undertaken in Crete, Greece, to investigate the epidemiologic, clinical, and therapeutic aspects of Q fever. Over a period of 5 years (1989-1993), 1,298 patients were examined and 98 cases were identified. Individuals who were aged 20-29 years and 30-39 years appeared to have an increased risk of infection. Contact with animals was found to be a major risk factor for acquisition of Q fever. The predominant clinical manifestations of the infection were fever (91.7% of patients) and respiratory disease (88.5%), whereas hepatitis was the dominant feature in only a minority (7.1%) of patients. Chest radiographs frequently revealed pulmonary interstitial changes (36.4% of patients) and alveolar changes (34.4%). Abnormal echocardiographic findings were also observed. There was no difference in the duration of fever whether the patient received therapy with tetracycline or erythromycin, a finding that may be explained by the delay in initiating tetracycline therapy.

Adult↗
PubMed1995

Molecular characterization of the OXA-7 beta-lactamase gene.

The OXA-7 gene, which encodes an oxacillinase, was cloned from plasmid pMG202 of Escherichia coli isolate 7181 (A. A. Medeiros, M. Cohenford, and G. A. Jacoby, Antimicrob. Agents Chemother. 27:715-719, 1985) and sequenced. The nucleotide sequence of the OXA-7 gene was closely related to that of the OXA-10 (PSE-2) gene, with a derived amino acid sequence of the OXA-7 enzyme showing greater than 95% homology with those of OXA-10 and OXA-11.

Amino Acid Sequence↗
PubMed1995

Evidence for an efflux pump in multidrug-resistant Campylobacter jejuni.

Mechanisms of drug resistance in Campylobacter jejuni were investigated. Mutant strains 34PEFr, which was resistant to pefloxacin (128-fold increase in the MIC), and 34CTXr, which was resistant to cefotaxime (32-fold increase in the MIC) and which was derived from the susceptible parent 34s, were obtained by serial passages on pefloxacin and cefotaxime gradient plates, respectively. Both mutants showed cross-resistance to erythromycin, chloramphenicol, tetracycline, beta-lactams, and quinolones. While the quinolone resistance of strain PEFr could be explained by a mutation at codon 86 of the gyrA gene, the multidrug resistance phenotype of both strains was further investigated. Accumulation of pefloxacin, ciprofloxacin, and minocycline was measured by fluorometry and was found to be lower in the mutant strains than in the parent strain. Preincubation of the cells with carbonyl cyanide m-chlorophenylhydrazone, however, completely abolished this difference. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of outer membrane preparations from both mutant strains showed overexpression of two proteins of 55 and 39 kDa which were absent from the outer membranes of the wild-type strain. These results indicate that in C. jejuni 34PEFr and 34CTXr, multidrug resistance is associated with an efflux system with a broad specificity.

Anti-Bacterial Agents↗
PubMed1994

Prospective study of the impact of broad-spectrum antibiotics on the yeast flora of the human gut.

The effects of four antibiotics on the yeast flora of the human gut were evaluated. Forty adult cancer patients who received therapy with amoxicillin-clavulanate, ciprofloxacin, sulfamethoxazole-trimethoprim or ampicillin were studied prospectively. Quantitative stool cultures for yeasts were performed immediately before, at the end of and one week after the end of the antibiotic treatment. Amoxicillin-clavulanate caused a higher and more persistent increase in gastrointestinal colonization by yeasts compared to ciprofloxacin, sulfamethoxazole-trimethoprim or ampicillin. The present results are similar to those obtained in a mouse model of gastrointestinal colonization by Candida albicans when the same antibiotics were used.

Adult↗
PubMed1994

CD23 and IgE expression during the human immune response to cutaneous leishmaniasis: possible role in monocyte activation.

Leishmania brasiliensis causes cutaneous leishmaniasis (CL) in humans. During this infection, a variety of inflammatory mediators are produced by T cells and monocytes/macrophages. In the present study, we analysed serum IgE levels and their correlation with in situ expression of the low affinity receptor for IgE (Fc epsilon RII/CD23) in patients infected with L. brasiliensis before and following therapy. These analyses were compared to in situ expression of tumour necrosis factor-alpha (TNF alpha), interleukin 3 (IL3), interferon-gamma (IFN gamma) and IL4. Disease-free individuals from the same endemic area sensitized with L. brasiliensis antigens were also included in this work. Our data indicate that during infection, serum levels of IgE and TNF alpha increased and correlated with elevated in situ expression of CD23, IL4 and TNF alpha mRNA. This expression disappeared following successful treatment, but persisted in patients resistant to anti-leishmania therapy. Patients resistant to therapy differed from other cases by a dramatic decrease in their in vivo expression of IFN gamma protein. Analysis of CD23 function in purified human monocytes indicated that this antigen mediates IgE/anti-IgE-dependent TNF alpha production. These data suggest a possible in vivo role of CD23 in acute immune responses in human CL.

Animals↗
PubMed1994

An outbreak of diarrhoeal disease attributed to Shigella sonnei.

An outbreak of gastroenteritis occurred in a village on the Island of Crete, with 1479 inhabitants. One hundred and thirty-eight symptomatic patients from 57 different families were examined. Thirty percent of children under 12 years were affected compared with 4% of adolescents and adults (P < 0.0001). Thirty-five out of 105 stool cultures (33%) grew Shigella sonnei. Thirty-four isolates had the same susceptibility pattern and were sensitive to ampicillin, while one was resistant to this antibiotic. Thirty-three isolates had the same plasmid profile. Based on epidemiologic and environmental findings, it was concluded that the transmission of shigellosis was waterborne. Shigella were not isolated from water, but one of the three village springs was found to be contaminated with faecal coliforms. This spring was probably contaminated by sewage material, due to its proximity to a source of untreated sewage effluent. Implementation of environmental and control measures brought the epidemic to an end.

Adolescent↗
PubMed1994

Sandflies in the Greater Athens region, Greece.

During the period from May to October 1992, a survey of phlebotomine sandflies was conducted in the Greater Athens region where cases of human and canine leishmaniasis occur. Using castor-oil paper traps, a total of 3015 sandflies were caught. Of the identified specimens, 1002 (34.1%) were Phlebotomus neglectus, 541 (18.4%) were P. papatasi, 182 (6.2%) were P. tobbi, 50 (1.7%) were P. simici, 30 (1.0%) were P. alexandri, 3(0.4%) were P. sergenti and 1122 (38.2%) were Sergentomyia minuta. The seasonal activity of most Phlebotomus species was bimodal, while that of S. minuta was unimodal. The population density of sandflies varied significantly in different localities; it was low in most of the stations and high in some stations in the outskirts. Among the potential vectors of Leishmania spp., P. neglectus and P. Papatasi were the most widespread species. The former species showed high density in 12 of the 70 sampled stations, while the latter in only 4. Hence, the risk of transmission of sandfly-borne diseases is still present in the Greater Athens region.

Animals↗