Candida parapsilosis as a potent biocontrol agent against growth and aflatoxin production by aspergillus species

Aflatoxin contamination of food and feed stuff is a serious health problem and significant economic concerns. In the present study, the inhibitory effect of Candida parapsilosis IP1698 on mycelial growth and aflatoxin production in aflatoxigenic strains of Aspergillus species was investigated. Mycelial growth inhibitions of nine strains of aflatoxigenic and non-aflatoxigenic Aspergillus species in the presence of C. parapsilosis investigated by pour plate technique at different pH, temperature and time of incubation. Reduction of aflatoxin was evaluated in co-cultured fungi in yeast extract sucrose broth after seven days of incubation using HPLC method. The data were analyzed by SPSS 11.5. The presence of the C. parapsilosis at different pH did not affect significantly the growth rate of Aspergillm isolates. On the other hand, temperature and time of incubation showed to be significantly effective when compared to controls without C. parapsilosis [P<0.05]. In aflatoxigenic strains, minimum percentage of reductions in total aflatoxin and BI, 62, Gi, G2 fractions were 92.98, 92.54, 77.48, 54.54 and 72.22 and maximum percentage of reductions were 99.59, not detectable, 94.42, and not detectable in both GI and G2, respectively. C parapsilosis might employ as a good biocontrol agent against growth and aflatoxin production by aflatoxigenic Aspergillus species

Aflatoxin detoxification in rice using citric acid

Aflatoxins cause health hazards to human and animals and has also economical problems. Therefore, the detoxification effect of citric acid was investigated in rice as the main food of Iranian people. Initially 275 samples of rice were examined for aflatoxins by HPLC. The aflatoxins contaminated samples were later treated by aqueous citric acid and detoxification of aflatoxins were quantified using HPLC. Among the 275 samples analyzed, aflatoxin B1 and aflatoxin B2 were detected in 211 [76.72% of total] samples. Aflatoxin B1 was detected in 203 [73.82% of total] samples with a mean and standard deviation of 2.3 +/- 10.21ppb. Aflatoxin B2 together with aflatoxin B1 were detected in only 8 [2.91% of total] samples with a mean and standard deviation of 1.38 +/- 2.7ppb of aflatoxin B2 and 2.99 +/- 1.56 of aflatoxin B1 respectively. Aflatoxin B1 level in 5 samples [1.82%] was above the maximum tolerated level of aflatoxin B1 in Iran [5ppb]. However considering the Iranian maximum tolerated level for aflatoxins in rice [30ppb], only 3 [1.09%] samples were above the 30ppb and also in regard to the European maximum tolerated level for aflatoxins in rice [4ppb], only 9 [3.27%] samples were considered as higher than 4ppb. The HPLC assay showed that although aflatoxins with a concentration of<30 and<4 ppb in the rice samples were completely degraded, but 97.22% degradation occurred in rice contaminated with 30 and 4ppb when treated with 1N citric acid. These results revealed the efficacy of 1N citric acid in reducing aflatoxins levels in rice

Upregulation of the ERG11 gene in Candida krusei by azoles

Candida species are the agents of local and systemic opportunistic infections and have become a major cause of morbidity and mortality in the last few decades. Azole resistance in Candida krusei [C. krusei] species appears to be the result of gene alterations in relation to the ergosterol biosynthesis pathway, as well as efflux pumps. The main objective of this study was to examine the RNA expression of ERG 11 in C. krusei which had been identified to be resistance to azoles. The ERG11 mRNA expression was investigated in four Iranian clinical isolates of C krusei, which were resistant to fluconazole and itraconazole by a semiquantitative RT-PCR. The mRNA expression levels were observed in all four isolates by this technique. Furthermore, it was found that ERG11 expression levels vary among four representative isolates of C. krusei. Although DNA sequencing revealed no significant genetic alteration in the ERG 11 gene, one heterozygous polymorphism was observed in two isolates, but not in others. This polymorphism was found in the third base of codon 313 for Thr [ACT>ACC]. Major Even though such a polymorphism creates a new Earl restriction site, no significant effect was found on the resistance of C. krusei to azoles. Results of this investigation are consistent with previous studies and may provide further evidence for the genetic heterogeneity and complexity of the ergosterol biosynthetic pathway or efflux pumps

Fungal nail infections in Tehran, Iran

Onychomycosis results from invasion of the nail plate by dermatophytes, yeasts or mould species of fungi. The objective was to determine the etiological agents of onychomycosis. A total of 549 patients clinically suspected of onychomycosis were examined for causative fungal agents. Both direct microscopy and the cultures of the nail material were performed to identify the causative agents between 2004-2005 in Tehran, Iran. Out of 549 cases examined, 263 [47.9%] were mycologically proven cases of onychomycosis [139 finger, 124 toe nails], among those 33 [6.09%] were only positive in direct microscopic examination. From an etiological point of view, 21.85% of nail infections were caused by yeasts, 10.55% were infected by dermatophytes and 15.5% by non-dermatopyte moulds.Candida albicans was the common yeast causative agent [16.73%] followed by A. flavus [11.78%], T. mentagrophytes [10.26%], [2.66%], Aspergillus spp [1.90%], each of Rhizopus spp and Cladosporium spp [1.52%], C.giulliermondii [1.14%], Scopolariopsis spp. [1.14%], each of C. famata, C.glabrata, C. krusei, S. lusitania, Acremonium spp. [0.76%] and C. homicola [0.38%], T. rubrum [4.94%]. Candida species were most common responsible agent for onychomycosis in female hands [74.1%] followed by 17.26% non-dermatophyte moulds. Dermatophytes caused tinea unguim of hand [8.63%] and peduum [37.1%] in males. The yeasts of the Genus Candida and non-dermatophyte moulds are dominant cause of female finger nail onychomycosis and dermathophytes are principal causes of both finger and toe nails in males in Tehran

Performance of five phenotypical methods for identification of Candida isolates from clinical materials

Although Candida albicans is the most common etiologic agent of candidiasis, C. dubliniensis, has been emerged, as another pathogen resembles C. albicans in many phenotypic aspects and noted for its in vitro potential for fluconazole resistance. Since there was no evidence of any report about detection of this organism in Iran, this study was designed to use of five different tests for identification of Candida species with special reference to C. dubliniensis among 313 suspected Candida isolates in Tehran, capital of Iran. Overall, 199 [63.6%] C. albicans and 114 [36.6%] Candida spp. were identified. All 199 C. albicans isolates were found germ tube and chlamydospore positive. Different shades of green color colonies were yielded on CHROMagar Candida of which 23 [11.6%] showed dark green color indicative of C. dubliniensis. All but four C. albicans isolates grew well at 45 °C. These 4 isolates beyond to 23 dark green colony producers were suspected of being C.dubliniensis, later examined by API 20C AUX system. The results indicated that all 27 isolates were able to assimilate both xylose and alpha-methyl-D-glucoside, therefore these isolates were identified as C. albicans. Overall, C. dubliniensis had not been found in present study. It must be concluded that no single phenotypic test has proven to be highly effective, and the use of several tests may be necessary of these two closely related Candida species for definitive identification

Fungi as Causative agent of nasal polyps

Nasal polyposis is an inflammatory condition of unknown etiology that involves nasal and sinus mucous membrane. These polyps can impair a person's quality of life by nasal obstruction, recurrent sinusitis, persistent postnasal drainage, hyposmia, anosmia, changes in sense of taste and even bony destruction. It has been shown that chronic inflammation causes a reactive hyperplasia of the intranasal mucosal membrane which results in the formation of polyps. Recently, fungal elements were suspected to be the causative agent of chronic rhinosinusitis and a fungal etiology has been proposed to underlie severe nasal polyposis. The present study was undertaken to determine the role of fungi in development of nasal polyps. In this study resected polyps from 100 patients were examined by mycological and pathological methods for the presence of fungi. Fungal elements were shown in 9 samples by mycological methods and isolated fungi were Aspergillus flavus, Aspergillus fumigatus and Rhizopus sp. Tissue invasion by fungi also was seen by histopathological examination in 6 patients. Therefore, fungi could be considered as the causative factor in the development of nasal polyposis in those patients and since medical treatment of nasal polyps have become increasingly recognized in recent years, the present study also implying the benefits of topical antifungal therapy in such cases

Study on the sources of nosocomial fungal infections at intensive care unit and transplant wards at a teaching hospital in Tehran

The incidence of nosocomial fungal infections has increased dramatically during the past two decades as the consequence of continuous increase in the number of severely immunocompromised patients. This study was done to determine the presumptive sources of nosocomial fungal infections at the intensive care unit and transplant wards [in a university- based teaching hospital in Tehran] during a 10-month period. Totally 583 samples were obtained from the air, surfaces, health care workers and also from the patients at those wards. Mycological culture of the samples yielded growth of 25 different genus and species of fungi and the most common isolated fungi were Candida albicans, Penicillium spp., Aspergillus niger, and Cladosporium spp., respectively. It was noted that health care workers were carrying fungi on their hands [50%], nasal mu-cosa [57.6%], in oral cavity [38.6%] and also by their shoes [92.3%] and uniforms [92.7%]. Environmental fungal contamination was shown and it was more prominent at the intensive care unit. Hospitalization also had more significant effect on colonization of fungi in the patients at the latter ward. Therefore, the highly susceptible patients in present study were at the greatest risk of developing fungal infections and preventive measures were critical for prevention and control of these life-threatening fatal infections

Anti-Cryptococcal-Globulin-Latex production for rapid detection of cryptococcus neoformans polysaccharide antigen in cryptococcosis

Cryptococcosis has become the fourth leading life-threatening opportunistic infection in patients with AIDS, but also occurs in non-AIDS patients. In view of the increasing numbers of infection during last decade in Iran, use of rapid, sensitive and specific test for diagnosis of cryptococcal disease has become important than ever. We aimed to produce the reagents for latex cryptococcal antigen test. The antigen was prepared from NCPF 3168 strain of Cryptococcus neoformans. Anticapsular antiserum of C. neoformans raised in rabbits and latex carboxylate- modified beads were coated with antiserum. The maximally- reactive globulin dilution was obtained at dilution of 1:400. For evaluation of efficacy of reagents, challenged 38 BALB/C mice and other 38 mice were used as controls. The mice were bled and autopsied. Brain, heart and lung were checked by direct, histopathological and cultural examination for cryptococcosis. The sera from case and control mice were tested with Immunomycologic [Immy] kit and also our produced reagents [OPR] for detection of cryptococcal antigen. Moreover, 15 cerebrospinal fluid and 15 serum samples from patients with cryptococcal meningitis, 30 with aspergillosis, 30 with suspected other fungal infections, and 30 from healthy individuals were tested as well. The results showed that the sensitivity [97.3%] and specificity [100%] of OPR was quite comparable with those of Immy kit. Therefore, it could be regarded as a substitute for commercial kits

Fungal Involvement in Patients with Paranasal Sinusitis

Fungal involvement of the paranasal sinuses is frequently observed in the immunocompromised host and it can become lifethreatening if it is not diagnosed. Definitive diagnosis is made by tissue biopsy and culture. In this study biopsy materials of maxillary, ethmoidal and frontal sinuses of 60 patients with clinical manifestation of sinusitis and no response to medical therapy were assessed by mycological and pathological methods for the presence of fungi. Invasive fungal sinusitis was diagnosed in 3 patients and etiologic agents were C and ida albicans, Rhizopus sp. and Aspergillus fumigatus. Predisposing factors in these patients were leukemia, diabetes mellitus and previous sinus and polyp surgery, respectively. Allergic fungal sinusitis also was seen in one patient and Alternaria sp. isolated from the biopsy material. Only the patient with allergic form of disease survived but all the patients with invasive form of fungal infection were expired. This clearly underscores the need of early recognition of fungal sinusitis in at risk population in order to start urgent treatment. In this study Nocardia asteroids also was isolated from the biopsy sample in a patient with sinunasal adenocarcinoma