Fusarium verticillioides abscess of the nasal septum in an immunosuppressed child: case report and identification of the morphologically atypical fungal strain

Fungal Abscess of Anterior Nasal Septum Complicating Maxillary Sinus Fungal Ball Rhinosinusitis Caused by Aspergillus flavus: Case Report and Review of Literature

Anterior nasal septum abscess is not a rare clinical disease entity. In terms of the etiologies of the disease, bacteria are obviously more common than fungi. Fungal culture and pathological examination are essential for diagnosis of a fungal abscess of the anterior nasal septum and the basis of prescription of antifungal agents. We report a 57-year-old male patient who came to our outpatient clinic due to refractory nasal congestion for 3 weeks despite receiving treatments by a local medical doctor. Radical surgery with postoperative adjuvant radiotherapy for the right buccal cancer was carried out 14 years ago. The patient has diabetes mellitus and the blood sugar level has been well controlled by oral hypoglycemic agents over the past several years. Computed tomography revealed an abscess in the anterior septum along with rhinosinusitis. Incision and drainage of the nasal septum abscess and functional endoscopic sinus surgery were carried out. Fungal culture and pathological examination confirmed a fungal abscess in the anterior nasal septum and fungal ball rhinosinusitis. Antibiotics and an antifungal agent were given, and the postoperative course was uneventful. A dialectical argument was made regarding the causal relationship between the fungal abscess of the anterior nasal septum and maxillary fungal ball sinusitis. A literature review of the previous case reports was carried out to elucidate the immune status of patients of this disease. In order to reach a rapid establishment of a fungal abscess of the anterior nasal septum, clinicians should keep this disease in mind and remain vigilant. An immuno-compromised status is more commonly found in patients with fungal abscess of the anterior nasal septum and is another important characteristic of this disease. Prompt diagnosis and effective treatment are equally important in patients with lower immune status of this kind, and the latter is based on the former.

PCR diagnostic platforms for non-Aspergillus mold infections: ready for routine implementation in the clinic?

INTRODUCTION

While Aspergillus spp. remain the predominant cause of invasive mold infections, non-Aspergillus molds, such as the Mucorales or Fusarium spp., account for an increasing proportion of cases. The diagnosis of non-Aspergillus invasive mold infections (NAIMI) is challenging because of the low sensitivity and delay of conventional microbiological tests. Therefore, there is a particular interest to develop molecular tools for their early detection in blood or other clinical samples.

AREAS COVERED

This extensive review of the literature discusses the performance of Mucorales-specific PCR and other genus-specific or broad-range fungal PCR that can be used for the diagnosis of NAIMI in diverse clinical samples, with a focus on novel technologies.

EXPERT OPINION

PCR currently represents the most promising approach, combining good sensitivity/specificity and ability to detect NAIMI in clinical samples before diagnosis by conventional cultures and histopathology. Several PCR assays have been designed for the detection of Mucorales in particular, but also Fusarium spp. or Scedosporium/Lomentospora spp. Some commercial Mucorales PCRs are now available. While efforts are still needed for standardized protocols and the development of more rapid and simpler techniques, PCR is on the way to becoming an essential test for the early diagnosis of mucormycosis and possibly other NAIMIs.

Fungal nasal septum abscess caused by Aspergillus flavus complicating sinonasal surgery

The fungal nasal septum abscess is a rare localized invasive form of fungal rhinosinusitis. Rare cases have been described in the literature. In this article, we intend to describe a new case of fungal nasal septum abscess caused by Aspergillus flavus in diabetic patient after sinonasal surgery. A 53-year-old woman with a history of uncontrolled type 2 diabetes and asthma developed a nasal septum abscess after a sinonasal endoscopic surgery which was performed for nasal polyposis. Needle aspiration of the abscess was performed and the pus cultures were positive for Aspergillus flavus. The patient was treated with antifungal drugs and surgical drainage of the abscess. A clinical and biological improvement was observed. Her case has been followed up for 18 months, and there hasn't been any recurrence of the infection. The fungal nasal septum abscess should be suspected in patients who do not respond adequately to standard treatment of nasal septum abscess, especially patients with risk factors of fungal rhinosinusitis.

Colonization of human opportunistic Fusarium oxysporum (HOFo) isolates in tomato and cucumber tissues assessed by a specific molecular marker

Fusarium oxysporum is a large complex cosmopolitan species composed of plant pathogens, human opportunistic pathogens, and nonpathogenic isolates. Many plant pathogenic strains are known based on host plant specificity and the large number of plant species attacked. F. oxysporum is an opportunistic pathogen in humans with a compromised immune system. The objectives of this study were: (1) to develop a specific marker to detect human opportunistic F. oxysporum (HOFo) isolates; (2) to determine whether or not HOFo isolates can colonize and cause disease symptoms in plants; and (3) to assess Taiwan isolates sensitivity to two agro-fungicides. The primer pair, Primer 5/ST33-R, specifically amplifying Taiwan and international reference HOFo isolates was developed and used to detect and assess the distribution of a Taiwan isolate in inoculated tomato plants and tomato and cucumber fruit. Taiwan HOFo isolate MCC2074 was shown to colonize tomato roots, hypocotyls, and cotyledons, but did not show any visible symptoms. Four days after surface inoculation of tomato and cucumber fruit with the same isolate, MCC2074 was detected in the pericarp and locular cavities of both tomato and cucumber fruit and in columella of tomato fruit. Three Taiwan HOFo isolates were found to be moderately sensitive to azoxystrobin and highly sensitive to difenconazole.

LC-MS/MS Tandem Mass Spectrometry for Analysis of Phenolic Compounds and Pentacyclic Triterpenes in Antifungal Extracts of Terminalia brownii (Fresen)

Decoctions and macerations of the stem bark and wood of Terminalia brownii Fresen. are used in traditional medicine for fungal infections and as fungicides on field crops and in traditional granaries in Sudan. In addition, T. brownii water extracts are commonly used as sprays for protecting wooden houses and furniture. Therefore, using agar disc diffusion and macrodilution methods, eight extracts of various polarities from the stem wood and bark were screened for their growth-inhibitory effects against filamentous fungi commonly causing fruit, vegetable, grain and wood decay, as well as infections in the immunocompromised host. Ethyl acetate extracts of the stem wood and bark gave the best antifungal activities, with MIC values of 250 µg/mL against Nattrassia mangiferae and Fusarium verticillioides, and 500 µg/mL against Aspergillus niger and Aspergillus flavus. Aqueous extracts gave almost as potent effects as the ethyl acetate extracts against the Aspergillus and Fusarium strains, and were slightly more active than the ethyl acetate extracts against Nattrassiamangiferae. Thin layer chromatography, RP-HPLC-DAD and tandem mass spectrometry (LC-MS/MS), were employed to identify the chemical constituents in the ethyl acetate fractions of the stem bark and wood. The stem bark and wood were found to have a similar qualitative composition of polyphenols and triterpenoids, but differed quantitatively from each other. The stilbene derivatives, cis- (3) and trans- resveratrol-3-O-β-galloylglucoside (4), were identified for the first time in T. brownii. Moreover, methyl-(S)-flavogallonate (5), quercetin-7-β-O-di-glucoside (8), quercetin-7-O-galloyl-glucoside (10), naringenin-4'-methoxy-7-pyranoside (7), 5,6-dihydroxy-3',4',7-tri-methoxy flavone (12), gallagic acid dilactone (terminalin) (6), a corilagin derivative (9) and two oleanane type triterpenoids (1) and (2) were characterized. The flavonoids, a corilagin derivative and terminalin, have not been identified before in T. brownii. We reported earlier on the occurrence of methyl-S-flavogallonate and its isomer in the roots of T. brownii, but this is the first report on their occurrence in the stem wood as well. Our results justify the traditional uses of macerations and decoctions of T. brownii stem wood and bark for crop and wood protection and demonstrate that standardized extracts could have uses for the eco-friendly control of plant pathogenic fungi in African agroforestry systems. Likewise, our results justify the traditional uses of these preparations for the treatment of skin infections caused by filamentous fungi.

Development of a polymerase chain reaction-restriction fragment length polymorphism method for identification of the Fusarium genus using the transcription elongation factor-1α gene

Fusarium species are well-known plant pathogens and food contaminants that have also appeared as one of the most important groups of medically significant fungi. The sequences of the translation elongation factor (TEF)-1α gene have been broadly employed for species detection. A total of 50 strains of Fusarium spp., including environmental, clinical and reference isolates were used for the current study. The primer sets, Fu3f and Fu3r, were used to amplify an ~420-bp DNA fragment of the TEF-1α gene. Double digestion with two restriction enzymes, XhoI and SduI was used for discrimination of the Fusarium species in the TEF-1α gene fragment. Double digestion of the TEF-1α gene fragment from five clinically important Fusarium species were clearly differentiated from each other: The F. solani species complex, F. oxysporum species complex, F. verticillioides, F. proliferatum and F. fujikuroi. This method facilitates detection and enables verification of the Fusarium genus; therefore, it may be applied for disease control.

Disseminated fusariosis by Fusarium proliferatum in a patient with aplastic anaemia receiving primary posaconazole prophylaxis - case report and review of the literature

Disseminated fusariosis is a life-threatening, invasive, opportunistic infection in immunocompromised patients, especially those with haematological malignancies. The prognosis is poor because these fungi are resistant to many of the available antifungal agents. We present a case of disseminated fusariosis caused by Fusarium proliferatum in a patient with severe aplastic anaemia complicated by a secondary infection of Aspergillus flavus, with a fatal outcome. We also review the documented Fusarium infections in immunocompromised hosts.

Gene expression profile and toxic effects in human bronchial epithelial cells exposed to zearalenone

Zearalenone (ZEA), a mycoestrogen produced by Fusarium fungal species, is mainly found in cereal crops such as maize, wheat and barley. Although ZEA has been reported to be present in air, little is known about the health risk or the molecular basis of action when lung cells are exposed to ZEA. As ZEA has a similar structure to estrogen, its potential risk as an endocrine disrupting chemical (EDC) has thus aroused both environmental and public health concerns. The purpose of this study is to identify the responses and underlying molecular changes that occur when human bronchial epithelial BEAS-2B cells are exposed to ZEA. Differential gene expression profiles were identified in cells that were treated with 40 µM ZEA for 6 h and 24 h by high-throughput microarray analysis using Affymetrix Human Gene 2.0 GeneChip. The array results showed that after ZEA treatment, 262 genes at 6 h and 1073 genes at 24 h were invovled in the differential regulation. Pathway analysis revealed that diverse cellular processes were affected when lung cells were exposed to ZEA resulting in impaired response to DNA damage, cell cycle arrest, down-regulation of inflammatory responses and alterations of epigenetic marks. Results of further experiments indicated that 40 µM ZEA decreased cell viability, induced apoptosis and promoted reactive oxygen species (ROS) generation in a time-dependent manner. Immuno-suppressive effects of ZEA were further revealed through the suppression of lipopolysaccharide (LPS)-induced expression of pro-inflammatory cytokines (IL-6, IL-8 and IL-1β). Interestingly, the level of global DNA methylation was markedly decreased after 24 h exposure to ZEA. Collectively, these observations suggested that a broad range of toxic effects are elicited by ZEA. Particularly, ROS may play a pivotal role in ZEA-induced cell death. These adverse effects observed in lung cells suggest that exposure to ZEA may increase susceptibility of lung cells to diseases and required further investigations.

Cluster of Fusarium verticillioides bloodstream infections among immunocompetent patients in an internal medicine department after reconstruction works in Larissa, Central Greece

BACKGROUND

Fusarium spp. can cause disseminated infections, particularly in immunocompromised patients. Fusarium verticillioides is a human pathogen, and sporadic cases of fusariosis have been reported.

AIM

To report a nosocomial cluster of F. verticillioides bloodstream infections among seven immunocompetent inpatients following reconstruction works.

METHODS

Identification was performed using macroscopic and microscopic morphology, and molecular assays (sequencing the nuclear ribosomal internal transcribed spacer region and translation elongation factor-1α gene). Susceptibility testing was performed in accordance with the guidelines of the Clinical and Laboratory Standards Institute. Environmental surveillance specimens were taken and cultured on Sabouraud dextrose agar plates.

FINDINGS

In total, 16 blood cultures obtained from the seven patients were positive for F. verticillioides. All surveillance cultures were negative.

CONCLUSIONS

In order to prevent fungaemia, it is important to implement effective infection control measures, before, during and after demolition and construction activities in healthcare settings.

Fusarium infection: report of 26 cases and review of 97 cases from the literature

Fusarium species is a ubiquitous fungus that causes opportunistic infections. We present 26 cases of invasive fusariosis categorized according to the European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) criteria of fungal infections. All cases (20 proven and 6 probable) were treated from January 2000 until January 2010. We also review 97 cases reported since 2000. The most important risk factors for invasive fusariosis in our patients were compromised immune system, specifically lung transplantation (n = 6) and hematologic malignancies (n = 5), and burns (n = 7 patients with skin fusariosis), while the most commonly infected site was the skin in 11 of 26 patients. The mortality rates among our patients with disseminated, skin, and pulmonary fusariosis were 50%, 40%, and 37.5%, respectively. Fusarium solani was the most frequent species, isolated from 49% of literature cases. Blood cultures were positive in 82% of both current study and literature patients with disseminated fusariosis, while the remaining 16% had 2 noncontiguous sites of infection but negative blood cultures. Surgical removal of focal lesions was effective in both current study and literature cases. Skin lesions in immunocompromised patients should raise the suspicion for skin or disseminated fusariosis. The combination of medical monotherapy with voriconazole or amphotericin B and surgery in such cases is highly suggested.

Identification and sensitivity of two rare fungal species isolated from two patients with Fusarium keratomycosis

We report two cases of Fusarium keratomycosis in which molecular analysis was used to identify two rare causative Fusarium species. A 65-year-old woman was diagnosed with Fusarium keratomycosis caused by F. equiseti, confirmed by sequencing the internal transcribed spacer (ITS) region and morphological characteristics. She was initially treated with topical corticosteroid but the keratitis did not improve. Even after aggressive antifungal treatment, there was a severe reduction of vision. In the end, the eye perforated. Our second case was a 75-year-old man who had diabetes mellitus. He developed keratitis after his cornea was injured by corn stalks. The ITS region identified the causative organism as F. verticillioides. Unlike the first case, he had good visual recovery after early antifungal therapy. Our findings demonstrate that both ITS and morphological characteristics can be used to identify the exact Fusarium species causing Fusarium keratomycosis. This allowed us to determine the sensitivity of these species to antifungal drugs that can be used to treat patients with these species of Fusarium.

Nasal septal abscess in children: from diagnosis to management and prevention

BACKGROUND

Nasal septal abscess (NSA) is an uncommon condition. It is a collection of pus in the space between the nasal septum and its overlying mucoperichondrium and/or mucoperiosteum. If left untreated, there are risks of intracranial complications, facial deformity, and delayed facial growth. There is no universally agreed consensus on the treatment of this condition. This study reviews evidence in the literature to determine its etiology, presentation, investigation, management options, and outcome.

METHOD

A structured review of the PubMed, EMBASE and the Cochrane Collaboration databases (Cochrane Central Register of Controlled Trials, Cochrane Database of Systemic Reviews) was undertaken, using the MeSH terms: nasal septum, nasal cartilage, trauma, hematoma, abscess, reconstructive surgery, rhinoplasty, pediatric, and children.

RESULTS

A total of 159 citations from 1920 to date were reviewed regarding nasal septal abscess, of which 81 articles were identified to be relevant to this review. No randomized controlled trials or systematic reviews were found in the Cochrane Collaboration database, PubMed or EMBASE. NSA is more common in children and in male. Nasal trauma and untreated septal hematoma are the leading cause. Staphylococcus aureus is isolated in up 70% of the cases. Clinically, nasal septal swelling, pain and tenderness, with purulent discharge are mostly evident. The immediate management of NSA is incision and drainage and antibiotic therapy. Recent studies suggest early septal reconstruction in children in order to prevent immediate and late facial deformity and nasal dysfunction. Autologous cartilage is the implant material of choice.

CONCLUSION

Nasal septal abscess is a serious condition that necessitates urgent surgical management in order to prevent potential life threatening complications. In the growing child, early reconstruction of destructed septal cartilage is essential for normal development of the midface (nose and maxilla).

Aspergillus terreus accessory conidia are multinucleated, hyperpolarizing structures that display differential dectin staining and can induce heightened inflammatory responses in a pulmonary model of aspergillosis

In addition to phialidic conidia (PC), A. terreus produces accessory conidia (AC) both in vitro and in vivo. AC are distinct from PC in cell surface architecture, with the AC surfaces displaying more β-glucan, a molecule that can be a trigger for the induction of inflammatory responses. The present study follows β-glucan cell surface presentation throughout the course of germination of both types of conidia, and analyzes the differential capacity of AC and PC to elicit immune responses. Results show that AC display early, increased dectin-1 labeling on their cell surfaces compared to PC, and this differential dectin-1 labeling is sustained on the cell surface from the time of breaking dormancy through early germ tube emergence. Mouse alveolar macrophages showed a stronger inflammatory cytokine/chemokine response when challenged with AC than with PC in both ex vivo and in vivo experiments, correlating with the greater exposure of β-glucan exhibited by AC. Further, histopathologic staining of the lungs from mice challenged with AC demonstrated heightened cell recruitment and increased inflammatory response compared to the lungs of mice challenged with PC. Our study also demonstrates that AC are multinucleate structures with the ability to germinate rapidly, polarizing in multiple directions and producing several hyphal extensions. We present evidence that A. terreus AC are phenotypically distinct from PC and can be potent activators of the innate immune mechanism thus possibly playing a role in this organism's pathogenesis.

Lessons from animal studies for the treatment of invasive human infections due to uncommon fungi

Clinical experience in the management of opportunistic infections, especially those caused by less common fungi, is, due to their rarity, very scarce; therefore, the most effective treatments remain unknown. The ever-increasing numbers of fungal infections due to opportunistic fungi have repeatedly proven the limitations of the antifungal armamentarium. Moreover, some of these fungi, such as Fusarium spp. or Scedosporium spp., are innately resistant to almost all the available antifungal drugs, which makes the development of new and effective therapies a high priority. Since it is difficult to conduct randomized clinical trials in these uncommon mycoses, the use of animal models is a good alternative for evaluating new therapies. This is an extensive review of the numerous studies that have used animal models for this purpose against a significant number of less common fungi. A table describing the different studies performed on the efficacy of the different drugs tested is included for each fungal species. In addition, there is a summary table showing the conclusions that can be derived from the analysis of the studies and listing the drugs that showed the best results. Considering the wide variability in the response to the antifungals that the different strains of a given species can show, the table highlights the drugs that showed positive results using at least two parameters for evaluating efficacy against at least two different strains without showing any negative results. These data can be very useful for guiding the treatment of rare infections when there is very little experience or when controversial results exist, or when treatment fails.

Use of mass spectrometry to identify clinical Fusarium isolates

Fusarium spp. have recently emerged as significant human pathogens. Identification of these species is important, both for epidemiological purposes and for patient management, but conventional identification based on morphological traits is hindered by major phenotypic polymorphism. In this study, 62 strains, or isolates, belonging to nine Fusarium species were subjected to both molecular identification TEF1 gene sequencing and matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) analysis. Following stringent standardization, the proteomic-based method appeared to be both reproducible and robust. Mass spectral analysis by comparison with a database, built in this study, of the most frequently isolated species, including Fusarium solani, Fusarium oxysporum, Fusarium verticilloides, Fusarium proliferatum and Fusarium dimerum, correctly identified 57 strains. As expected, the four species (i.e. Fusarium chlamydosporum, Fusarium equiseti, Fusarium polyphialidicum, Fusarium sacchari) not represented in the database were not identified. Results from mass spectrometry and molecular identification agreed in five of the six cases in which results from morphological and molecular identification were not in agreement. MALDI-TOF yielded results within 1 h, making it a valuable tool for identifying clinical Fusarium isolates at the species level. Uncommon species must now be added to the database. MALDI-TOF may also prove useful for identifying other clinically important moulds.

A case of invasive rhinosinusitis by Fusarium verticillioides (Saccardo) Nirenberg in an apparently immunocompetent patient

A case of chronic invasive rhinosinusitis in an apparently healthy man, caused by Fusarium verticillioides, is described. The identity of the isolate as F. verticillioides was established by demonstrating characteristic morphological features and by amplification of rDNA using species-specific primers. Surgical debridement of the infected nasal tissue and therapy with amphotericin B resulted in a favorable outcome. To the best of our knowledge, F. verticillioides has not been described previously to cause this condition.

Fusarium infections in immunocompromised patients

Fusarium species cause a broad spectrum of infections in humans, including superficial, locally invasive, and disseminated infections. The clinical form of fusariosis depends largely on the immune status of the host and the portal of entry, with superficial and localized disease occurring mostly in immunocompetent patients and invasive and disseminated disease affecting immunocompromised patients. Risk factors for severe fusariosis include prolonged neutropenia and T-cell immunodeficiency, especially in hematopoietic stem cell transplant recipients with severe graft-versus-host disease. The most frequent presentation of disseminated fusariosis is a combination of characteristic cutaneous lesions and positive blood cultures, with or without lung or sinus involvement. The prognosis is poor and is determined largely by degree of immunosuppression and extent of infection, with virtually a 100% death rate among persistently neutropenic patients with disseminated disease. These infections may be clinically suspected on the basis of a constellation of clinical and laboratory findings, which should lead to prompt therapy. Treatment options include the lipid formulations of amphotericin B, voriconazole, and posaconazole. Prevention of fusarial infection among high-risk patients should be considered.

Emerging Fungi

The hyalohyphomycetes (especially Fusarium spp) have emerged as significant pathogens in severely immunocompromised patients. Human infections by Fusarium spp can be superficial or limited to single organs in otherwise healthy patients. Such infections are rare and tend to respond well to therapy. By contrast, disseminated fusarial hyalohyphomycosis affects the immunocompromised host and frequently is fatal. Successful outcome is determined by the degree of immunosuppression and the extent of the infection. These infections may be suspected clinically on the basis of a constellation of clinical and laboratory findings, which should lead to prompt therapy.

Phaeoacremonium parasiticum infections confirmed by beta-tubulin sequence analysis of case isolates

Phaeoacremonium parasiticum is an agent of opportunistic phaeohyphomycosis belonging to a genus encompassing numerous recently described and soon-to-be-described, difficult-to-identify human pathogens. It appears in the literature to be an uncommon etiologic agent, yet we encountered several cases in a single year. Each presented problems in laboratory identification and case management. We present two cases of invasive disease with definite identification and susceptibility results. These cases are analyzed in relation to a brief review of previous cases known to have been caused by this species. Our first case involved a 40-year-old male cardiac transplant recipient with multiple localized skin lesions. The second featured a 31-year-old female with aplastic anemia and prolonged neutropenia who developed disseminated disease, with multiple positive blood cultures and skin lesions. Both patients died despite aggressive surgical and antifungal therapy. Fungal susceptibility testing showed that our isolates appeared to be susceptible to amphotericin B, itraconazole, voriconazole, ravuconazole, and posaconazole. Because phenotypic identification of Phaeoacremonium is notably problematic, sequence-based confirmation was performed using a recently proposed standard based on use of a segment of the 5' end of the beta-tubulin gene. Sequences from both isolates involved in the cases were over 99% similar to the corresponding sequence of the ex-type isolate of P. parasiticum. The close DNA similarity, corroborated by relevant morphological similarities (e.g., long, thin phialides and tuberculate hyphae bearing warts up to 3 mum high), confirms these two isolates as P. parasiticum.

Multiplex PCR-based detection of potential fumonisin-producing Fusarium in traditional African vegetables

Culture-independent methods employed in fungal genetic studies using in vitro amplification (PCR) and analysis of specific genes or gene fragments have proved to be useful for detection, identification, and molecular taxonomy of various plant pathogens including Fusarium spp. This approach may be faster than culture-dependent methods, and could especially be of value for the rapid detection of slow-growing toxin-producing species in food samples. The present study was aimed at the development and evaluation of multiplex PCR-based methods for the detection and identification of potential fumonisin-producing Fusarium spp. in traditional morogo-leafy vegetables supplementing the maize-based staple diet of rural communities in South Africa. In these rural subsistence settings, some morogo plants grow as weeds in maize fields where they might become contaminated with potential fumonisin-producing Fusarium strains before being collected for consumption. Substances released by senescent vegetables could induce toxin production during storage. Using fumonisin-positive MRC Fusarium verticillioides strains as reference cultures, the following primer sets for the detection of specific gene fragments in fumonisin-positive Fusarium spp. were evaluated: (i) the conserved transcription elongation factor gene (EF-1), (ii) the FUM1 gene encoding polyketide synthase for fumonisin B1 production, and (iii) 18S rRNA gene. Preliminary results indicated that, these DNA fragments were amplified from MRC reference strains as well as Fusarium spp. isolated from morogo. The annealing temperature for the multiplex PCR was 55 degrees C and each reaction contained 25 pmol of each of the primer sets EF and FUM1 and 12.5 pmol of the 18S primer set. The detection limit of the individual primers was up to 1 ng and for the multiplex up to 10 ng. This demonstrates the potential of this method for the detection of potential fumonisin-positive strains.

Use of the Diversi Lab System for species and strain differentiation of Fusarium species isolates

Advances in molecular typing of fusariosis would facilitate the study of its epidemiology. We tested 26 such isolates by the commercially available Diversi Lab System. The system utilizes automated repetitive sequence-based PCR (rep-PCR) and web-based data analyses. rep-PCR dendrogram cluster analysis showed agreement with species sequence identification (elongation factor 1 alpha gene). Additionally, subtype differences within the same species were noted.