Biomedical subjects

G Samonis

Publications and source records attributed to G Samonis.

At least 73 records · Page 4Linked 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

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

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↗

PubMed1995

Role of catheter colonization and infrequent hematogenous seeding in catheter-related infections.

Adult cancer patients were prospectively studied to determine the relationship between ultrastructural and microbiologic catheter colonization and clinical catheter-related infections. Participants included 38 patients whose central venous catheters were removed because of suspected catheter infection (16 patients) or other noninfectious causes (22 controls). The presence of clinical infection was determined. Catheters were examined by microbiologic methods (sonication and roll-plate culture) and by scanning and transmission electron microscopy. Ultrastructural microbial colonization and biofilm formation were universal and occurred as early as one day after catheter insertion. The extent of biofilm formation was unrelated to the clinical status of patient or the catheter microbiological findings. Secondary seeding of catheters was rarely seen. Catheter microbial biofilm formation occurs early, is universal and does not necessarily represent an infectious condition.

Adult↗

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

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

Antibiotics affecting gastrointestinal colonization of mice by yeasts.

A group of three-month old, male Crl:CD1(ICR) BR mice, was fed chow containing Candida albicans, while another group of the same type of mice was fed regular chow. Both groups were treated subsequently with either antibiotics or normal saline for 10 days. Stool cultures were performed before treatment, at the end of treatment, and one week after the end of treatment, to determine the level of colonization of the gastrointestinal tract by the yeast. The stools of mice fed Candida and treated with antibiotics had substantially higher Candida counts than control mice fed C. albicans and treated with saline. The highest concentrations of the yeast were observed in the stools of mice treated with cefotaxime as compared to those of mice treated with pefloxacin, amikacin and amoxicillin. No Candida was found in the stools of mice fed regular chow and treated with antibiotics or saline. Dissemination of Candida was not observed in the visceral organs of any mouse.

Amikacin↗

PubMed1994

Murine yeast gut flora affected by tetracycline, metronidazole and norfloxacin.

Three-month old, male Crl:CD1(ICR) BR mice, were fed food containing Candida albicans, while other mice of the same type were fed regular food. Both groups of mice were subsequently given orally either antibiotics or normal saline for a 10-day period. The stools of all mice were cultured before, at the end, and one week after the end of the antibiotic treatment, to determine the level of gut colonization by the yeast. The mice fed Candida and treated with antibiotics had substantially higher Candida counts in their stools than control mice fed C. albicans and treated with saline. The concentrations of Candida in the stools of mice treated with tetracycline were much higher when compared to those of mice treated with metronidazole and norfloxacin. Tetracycline was associated with a statistically significant increase of gastrointestinal Candida colonization. Yeast was not found in the stools of mice fed regular food and treated with antibiotics or saline. Histopathologic examination did not reveal dissemination of Candida in the visceral organs of any mouse.

Administration, Oral↗

PubMed1994

Infections due to Cunninghamella bertholletiae in patients with cancer: report of three cases and review.

Limited information is available regarding the pathogenesis and clinical manifestations of infection with Cunninghamella bertholletiae. In this report, we describe the clinical courses of three patients with leukemia and fatal C. bertholletiae infection and review the literature. In all patients, the infection developed in the setting of severe neutropenia following high doses of cytotoxic chemotherapy. Clinical presentation always consisted of fever and pneumonia and could be associated with dissemination to numerous organs. The course of infection was very rapid, and the diagnosis was made around or after the time of death. The most important risk factors for C. bertholletiae infection described in the literature include corticosteroid administration and prolonged severe granulocytopenia. Four infectious syndromes due to Zygomycetes have been described: rhinocerebral, pulmonary, cutaneous and soft tissue, and disseminated. The outcome of disseminated infection with C. bertholletiae has been almost uniformly fatal. Most previously described patients, however, did not receive aggressive treatment consisting of amphotericin B administration, resection of infected tissues, and, most importantly, control of the underlying disease.

Aged↗

PubMed1994

Effects of broad-spectrum antibiotics on colonization of gastrointestinal tracts of mice by Candida albicans.

Three-month-old, male, Crl:CD1 (ICR) BR mice were fed chow containing Candida albicans or regular chow. Subsequently, both groups were given either antibiotics or normal saline for 10 days. Stool cultures were performed immediately before administration, at the end of antibiotic administration, and 1 week after the discontinuation of antibiotics, to determine the effect on the concentration of C. albicans in the stools. The stools of mice fed C. albicans and given antibiotics had substantially higher Candida counts than those of control mice fed C. albicans and given saline. Significantly higher candidal concentrations were observed in the stools of mice given chloramphenicol compared with those of mice given ciprofloxacin, sulfamethoxazole-trimethoprim, and ampicillin. No mice developed histopathological evidence of local gastrointestinal invasion or disseminated candidiasis. In this mouse model, Candida colonization increases substantially after the administration of antimicrobial agents with broad spectra and anaerobic activities.

Animals↗

PubMed1994

Surgical wound infection caused by Rahnella aquatilis.

Rahnella aquatilis is a water-residing gram-negative rod, a member of the family Enterobacteriaceae, isolated rarely from clinical specimens of immunocompromised patients. A case of a surgical wound infection caused by R. aquatilis in a patient who underwent a prosthetic surgical intervention is reported. The presence of inducible beta-lactamase was suggested by the disk induction test and the conventional agar dilution assay. Literature on R. aquatilis infections in humans is reviewed.

Enterobacteriaceae↗

PubMed1994

TMJ: a well-tolerated high-dose regimen for the adjuvant chemotherapy of high risk breast cancer.

Following local treatment and doxorubicin-containing standard chemotherapy, 42 patients with surgical Stage II or IIIA breast cancer containing ten or more involved axillary nodes and 13 patients with Stage IIIB disease were treated with high-dose chemotherapy (TMJ) consisting of thiotepa (750 mg/m2), mitoxantrone (40 mg/m2), and carboplatin (1000 mg/m2), with autologous bone marrow (ABM) and peripheral stem cell (PSC) transplant, followed by irradiation and/or hormone therapy. Sargramostim (GM-CSF) support was given to most patients. The median time to transfusion independence was two weeks. Severe non-hematologic toxicity was uncommon, with no intensive care admission or treatment-related death. At a median follow-up of 17 months, eight patients have relapsed and five have died of tumor progression. No statement can yet be made regarding adjuvant efficacy, but this high-dose regimen is very well tolerated.

Adult↗

PubMed1993

First-line combination chemotherapy with mitoxantrone, methotrexate, vincristine and carboplatin (MIMOC) in advanced breast cancer.

51 patients with stage IIIB and IV breast cancer entered a prospective phase II study of combination chemotherapy that consisted of mitoxantrone (8 mg/m2) day 1, methotrexate (25 mg/m2) day 1, vincristine (1 mg/m2) day 2 and carboplatin (250 mg/m2) day 2 (MIMOC) given in a 3-weekly schedule. None had received prior chemotherapy for metastatic disease, although 16 patients were given adjuvant chemotherapy. Objective response to treatment was seen in 29 of 48 patients analysed for response (60%) with 8 complete responses (CR). 7 out of 8 patients with stage IIIB disease responded, 2 of them completely. Responses were seen in all sites but the best results were achieved in lung metastases with 50% CR. The median duration of response was 8 months and the median time to disease progression was 12 months. The main toxicity was nausea and vomiting which was severe in 20% of the patients. Other toxicities were mild. MIMOC was administered on an out-patient basis and appears to be effective as first-line treatment in advanced breast cancer.

Adult↗

PubMed1993

Comparison of the efficacy of polyenes and triazoles against hematogenous Candida krusei infection in neutropenic mice.

Candida krusei is reported to cause serious infections in immunocompromised patients, particularly those receiving prophylaxis with antifungal azoles. Treatment of this infection can be very challenging. The efficacy of amphotericin B, liposomal amphotericin B (three dosages), fluconazole, and D0870 (a new experimental oral bis-triazole) was assessed in a CF1 mouse model of hematogenous C. krusei infection. Increased survival time and reduced kidney fungal burden were achieved with treatment with amphotericin B at 2 mg/kg/day and liposomal amphotericin B at 8 and 15 mg/kg/day. D0870 at 25 mg/kg/day increased survival time but had no effect on clearance from organs, while the survival and clearance from organs of mice treated with fluconazole at a dose of 100 mg/kg/day did not differ from those of untreated animals. These findings suggest that deoxycholate and liposome-encapsulated amphotericin B are active against disseminated C. krusei infection in neutropenic mice and confirm the in vitro and in vivo resistance of this species to fluconazole.

Amphotericin B↗

PubMed1993

Prospective evaluation of effects of broad-spectrum antibiotics on gastrointestinal yeast colonization of humans.

This study evaluated the effects of broad-spectrum antibiotics on the gastrointestinal (G.I.) yeast flora of humans and correlated the findings with those obtained from a mouse model of G.I. colonization by Candida albicans. We prospectively studied 46 adult cancer patients who received one of five broad-spectrum antibiotics (ceftriaxone, ceftazidime, ticarcillin-clavulanic acid, imipenem-cilastatin, and aztreonam) as therapy for infections. Quantitative examination of yeast colonization of stools was conducted at the baseline, at the end of antibiotic treatment, and 1 week after discontinuation of therapy. Antibiotics with anaerobic activity (ticarcillin-clavulanic acid) or high G.I. concentrations (ceftriaxone) caused a higher and more sustained increase in G.I. colonization by yeasts than did antibiotics with poor anaerobic activity (ceftazidime and aztreonam) or a low G.I. concentration (imipenem-cilastatin). These results were similar to those obtained with a mouse model of G.I. colonization by C. albicans that involved the same antibiotics. Hence, the mouse model may be useful for evaluation of yeast colonization of the human G.I. tract.

Adult↗

PubMed1991

Review of Citrobacter bacteremia in cancer patients over a sixteen-year period.

A review was conducted of 65 episodes of Citrobacter bacteremia in cancer patients during a 16-year period. Cases of polymicrobial bacteremia were excluded from this analysis. The infection occurred most commonly in patients with acute leukemia. Most patients acquired the infection in the hospital, and 57% had received antibiotic therapy during the preceding ten days. Fever occurred in 98% of cases and shock in 17%. Thirty-eight percent of patients had concomitant pneumonia. Patients with shock, pneumonia or hemorrhage had a substantially poorer prognosis. The response rate was 72% for patients who received appropriate antibiotics. Patients who continued to have positive blood culture results while receiving appropriate antibiotic therapy had a poor prognosis. Beta-lactam antibiotics were more effective than aminoglycosides.

Adolescent↗

PubMed1990

Effects of broad-spectrum antimicrobial agents on yeast colonization of the gastrointestinal tracts of mice.

Male Crl:CD1 (ICR) BR mice, 3 months old, were fed regular chow or chow containing Candida albicans. Subsequently, both groups were treated with either antibiotics or normal saline for 10 days. Stool cultures were obtained to determine the extent of C. albicans colonization immediately before treatment, at the end of treatment, and 1 week after the discontinuation of treatment. Animals in the antibiotic-treated groups had substantially higher Candida counts than control animals fed C. albicans, especially if they received ceftriaxone, cefoperazone, or ticarcillin-clavulanic acid. There was no evidence of Candida dissemination to internal organs.

Animals↗

PubMed1990

A model of sustained gastrointestinal colonization by Candida albicans in healthy adult mice.

Three-month-old male Crl:CD1(ICR)BR and C3H/HeJ mice were fed chow containing Candida albicans for 14 days, while similar control mice were fed regular food. Stool cultures were done for all mice before and after administration of the special diet. Stool cultures were repeated 48 h, 1 week, and 1 and 3 months after stopping the diet for Crl:CD1(ICR)BR mice and again 5 months afterward for C3H/HeJ mice. Some animals were sacrificed at the end of the special diet, and cultures and histopathologic examination of various organs were performed. Colonization with C. albicans occurred in the Candida-fed mice, and the fungus was maintained in the gastrointestinal tract at a concentration of 10(3) to 10(4) CFU/g of stool for up to 5 months. There was no histologic evidence of organ infection with Candida spp. The fungus was not found in stool cultures or organs of mice in the control group. The results suggest that persistent gastrointestinal colonization of adult mice by C. albicans can be achieved without immunosuppression. Thus, with additional manipulations, this model could be useful for studying the role of gastrointestinal colonization by C. albicans in the development of systemic infection.

Animal Feed↗