Nuran Yuluğ

Effect of subminimal inhibitory concentrations of three fluoroquinolones on adherence of uropathogenic strains of Escherichia coli

The effect of subinhibitory concentrations (1/2-1/32 x MIC) of ciprofloxacin, ofloxacin and levofloxacin on the adherence of three strains of Escherichia coli (a mannose-resistant haemagglutinating clinical isolate, a non-haemagglutinating clinical isolate and the mannose-resistant haemagglutinating ATCC 25922 strain) were studied. Ciprofloxacin had the lowest MIC values but only the 1/2 MIC concentration inhibited adherence of mannose-resistant haemagglutinating strains after exposure to subMIC values. Significant inhibition of adherence was observed with 1/4 x MIC ofloxacin for both haemagglutinating isolate (27096) and the ATCC strain. Levofloxacin might be more effective and safer than ciprofloxacin and ofloxacin as a long acting fluoroquinolone at subMIC values in patients with UTI.

Species distribution and antifungal susceptibilities of dermatophytes during a one year period at a university hospital in Turkey

Dermatophyte infections have been considered to be a major public health problem in many parts of the world. The aim of this study was to determine the causative agents of dermatophytoses and their antifungal susceptibilities in a Turkish University Hospital, west of Turkey. A total of 926 patients suspected to have dermatophytic lesions were examined over a period of 1 year (2001–2002). Samples collected from skin, hair and nails were submitted to direct microscopical examination using KOH and Calcofluor white stain, cultured on Sabouraud dextrose agar and Mycosel agar. The prevalence of dermatophytoses was 7.34% (68/926). Trichophyton rubrum was the most frequent dermatophyte isolated (56%) followed by T. mentagrophytes (38%), T. violaceum (1.5%), T. verrucosum (1.5%), Microsporum canis (1.5%) and Epidermophyton floccosum (1.5%). Tinea pedis (47%) was the most common type of infection, followed by tinea unguium (29%), tinea inguinalis (15%), tinea corporis (7.4%) and tinea capitis (1.6%). Secondary, we have tested 68 strains of dermatophytes against four antifungal agents following mainly the National Committee for Clinical Laboratory Standards M38‐P standard for filamentous fungi. In general, all antifungals were shown to be highly effective and itraconazole and naftifine appeared more active than ketoconazole and oxiconazole.

Effect of subminimal inhibitory concentrations of gentamicin, penicillin, trimethoprim-sulfamethoxazole on adherence of uropathogenic Escherichia coli strains.

Abstract Evaluating the adherence factor of uropathogenic Escherichia coli is important for assessing the relative efficiency of antimicrobials when used at sub-minimal inhibitory concentration (sub-MICs). The microdilution method was used to determine the MICs of gentamicin, trimethoprim-sulfamethaxozole and penicillin. Then the efficacy of antimicrobial sub-MICs was determined by hemagglutination and adherence assays. Instead of showing nearly the same MICs, gentamicin had nearly twice the activity of trimethoprim-sulfamethaxozole. Gentamicin, as a “long acting” agent, can be accepted as being more effective than trimethoprim-sulfamethaxozole or penicillin, especially at sub-MICs, against adherence factors of uropathogenic E. coli, and can be used as monotherapy for urinary tract infections.

Prevalence and antifungal susceptibilities of yeast isolates during one year at a university hospital in Turkey.

New technologies and therapies have helped to treat patients suffering from fatal diseases, therefore leading to an increase in the number of immuncompromised and hospitalized patients. The incidence of nosocomial infections has thus increased recently. Candida spp. are the most common pathogens detected in nosocomial fungal infections 1,2. It is important for every hospital to define the spectrum of pathogens causing nosocomial infection in its region and to determine their antifungal susceptibility in order to prevent infections. The aim of this study was to detect the type and susceptibility to antifungals of Candida species isolated from clinical samples that were sent to the Mycology Laboratory at Dokuz Eylul University Medical Faculty from January 1 to December 31, 2000. More than one isolate from a single patient was included if different species were detected, or if the specimens were from different sites. A total of 151 yeast isolates were identified. The isolates were first tested by germ tube test for presumed identification of Candida albicans. The species were also evaluated according to their morphology on corn meal agar (Oxoid) Tween 80 (Merck) 3. Confirmation of species identification was performed with Vitek products (bio-Merieux) as recommended by the manufacturer. The antifungal susceptibility of the 151 isolates to amphotericin B (Bristol-Myers Squibb, Turkey), ketoconazole (ilsan-iltas, Turkey) and fluconazole (Pfizer, Turkey) was determined. Antifungal susceptibility testing of yeast isolates was carried out using the broth microdilution method described by the National Committee for Clinical Laboratory Journal of Chemotherapy Vol. 14 n. 6 (640-641) 2002

Is there any relationship between fluconazole resistance and some virulence factors in Candida albicans strains

Fungal virulence factors are vital to the development of fungal infections. Candida albicans has enzymes such as phospholipase and proteinase that play a very important role in tissue invasion. C. albicans can attach to tissues and spread due to its ability to produce slime 1,2. It is not clear which of the virulence factors is more important in the development of infection and how they affect pathogenesis when they work together. Another interesting subject is the relationship between antifungal resistance and virulence factors. In our study we investigated whether a correlation is present between the activity of the virulence factors proteinase, phospholipase and slime-producing ability and whether there is a relationship between these virulence factors and resistance to fluconazole. Microorganisms investigated included 57 C. albicans clinical isolates from patients who were staying in hospital, some of whom had been previously treated with an antifungal agent (22 urine, 11 respiratory, 11 oral, 5 wound, 4 vaginal smear and 4 blood samples). Strains isolated from Sabouraud Dextrose Agar (SDA) media were typed according to their germ tube formation and morphological characteristics on Cornmeal-Tween 80 media. Strain type was also verified with the VITEK-YBC-1303 (Bio-Merieux/Diagno) automated diagnostic system. The Samaranayake method was used to determine phospholipase activity 3. According to this method the Pz value shows that precipitation activity is calculated by dividing the colony diameter by the diameter of the precipitation zone around the colony. Strains with a Pz value equal to 1.00 were classified as phospholipase negative and those with a value of less that 1.00 as positive 3. Proteinase activity was determined according to Journal of Chemotherapy Vol. 15 n. 6 (616-617) 2003

Evaluation of semisolid agar screening tests for determining fluconazole and amphotericin B susceptibilities of Candida strains by using three different media.

Abstract The susceptibilities of 164 Candida isolates against fluconazole and amphotericin B were determined by semisolid agar screening tests and the microdilution method according to NCCLS M27-A standards. The semisolid agar screening tests were performed with three different media containing 0.5% agar and 2, 8, and 40 μg/ml of fluconazole or 0.5 and 2.0 μg/ml of amphotericin B. These media were MOPS buffered RPMI 1640, brain-heart infusion and 1/3 diluted Sabouraud dextrose agar. The results of both methods were interpreted as susceptible, dose dependent susceptible and resistant for fluconazole and susceptible and resistant for amphotericin B. The agreement rates of semisolid agar screening tests using RPMI 1640, brain-heart infusion and Sabouraud dextrose media with the reference microdilution method were found to be 71.4%, 51.2%, and 57.3% for fluconazole and 79.3%, 53.7%, and 56.7% for amphotericin B, respectively. Overall, we conclude that semisolid agar screening tests using RPMI 1640 can be used for determining the susceptibilities of Candida isolates against fluconazole and amphotericin B in clinical microbiology laboratories.

Recovery period of the bladder after exposure to soluble virulence factor produced by Escherichia coli

Objectives: This study was designed to determine the time interval required for the recovery of the bladder after exposure to soluble virulence factor (SVF) in an animal model. In addition, we aimed to determine the changes in the epithelium during the recovery period. Methods: A total of 46 male New Zealand rabbits were used in this study. Sterile human urine was infected with Escherichia coli type O6 to obtain supernatant, which would contain SVF, but no bacteria. Rabbits were assigned to one of three groups comprising the supernatant urine group (SUG) and controls, respectively. Sterile human urine and supernatant urine were instilled to controls and SUG, respectively. Bacterial inoculation with E. coli was performed 1, 24 and 72 h after initial instillation. Histopathologic and microbiologic analyses were performed on these animals. Results: In SUG bacterial colonization was significantly higher than in controls 1 and 24 h after exposure to supernatant. Histopathologic analysis confirmed this finding. Histologic changes were most pronounced 1 hour after instillation of supernatant. A moderate degree of recovery was noted at 24 h, and complete recovery was seen at 72 h. Conclusion: Bacterial growth is potentiated by SVF–induced impaired bladder mucosa until the repairing process has been completed. During this time interval, SVF enables the colonization and growth of E. coli and other bacterium species that may result in sustained bacterial presence and recurrent infection.