Clinical Outcomes of Repeat Descemet Membrane Endothelial Keratoplasty After Graft Failure.

PURPOSE: To evaluate the clinical outcomes after repeat Descemet membrane endothelial keratoplasty (DMEK) for technical failure (TF) and secondary graft failure (SGF). METHODS: Retrospective analysis of 49 eyes that underwent repeat DMEK either for TF (ie, persistent graft detachment, n = 24) or for SGF (ie, late endothelial graft failure, n = 25). Surgery indications for primary DMEK were Fuchs endothelial corneal dystrophy (FECD, 80%) and bullous keratopathy (BK, 20%). Main outcome measures were best-corrected visual acuity (BCVA), endothelial cell density (ECD), corneal backscattering, pachymetry, and graft survival. Outcomes were compared with an age-matched control group of 49 primary DMEK eyes. RESULTS: Logarithm of the minimum angle of resolution BCVA improved from 0.92 ± 0.6 before to 0.20 ± 0.3 at 1 year after repeat DMEK with better outcomes for eyes with TF than those with SGF (P = 0.046). Donor ECD decreased from 2618 ± 171 cells/mm2 before to 1247 ± 422 cells/mm2 at 1 year postoperatively, with no difference between technical TF and SGF eyes (P > 0.05). One-year BCVA and ECD outcomes were better in the control group than in the repeat DMEK group (P < 0.05). Five-year graft survival probability after repeat DMEK was better for TF than for SGF eyes (100% vs. 75%, P = 0.010) and better for eyes with FECD than BK as primary indication for surgery (92% vs. 65%, P = 0.042). CONCLUSIONS: Repeat DMEK gives acceptable clinical outcomes especially when performed for TF in the early period after primary DMEK. Long-term graft survival probability after repeat DMEK is comparable to primary DMEK for FECD eyes, whereas BK eyes may show an elevated risk to develop graft failure again.

Bowman Layer Onlay Grafting as a Minimally Invasive Treatment for the Most Challenging Cases in Keratoconus.

PURPOSE: To analyze the clinical outcomes after Bowman layer (BL) onlay grafting for the treatment of progressive, advanced keratoconus. DESIGN: Prospective, interventional case series. METHODS: Twenty-one eyes underwent BL onlay grafting. After removing the epithelium, a single or double BL graft was "stretched" onto the corneal surface, allowed to dry-in, and a soft bandage lens was placed until the graft was re-epithelialized. Best spectacle- and/or best contact lens-corrected visual acuity (BSCVA/BCLVA), corneal tomography, and postoperative complication rates were analyzed for the total group and 2 subgroups (group 1: preoperative maximum keratometry [Kmax] <69 diopters [D; n = 7); group 2: preoperative Kmax ≥69 D [n = 14]). Follow-up ranged from 6 to 36 months (mean 21 ± 11 months). RESULTS: All 21 surgeries were uneventful. Overall, Kmax changed from 76 ± 12 D preoperatively to 72 ± 9 D at 6 to 36 months postoperatively (P = .015). Kmax decreased by 6 D in group 2 (P = .002) but did not change in group 1. Average BSCVA remained stable for group 1 and improved from preoperatively 0.8 ± 0.4 to 0.4 ± 0.2 logarithm of the minimum angle of resolution postoperatively in group 2 (P = .032); BCLVA remained stable (P > .05). Within the first postoperative weeks, 2 eyes required BL graft repositioning after inadvertent bandage lens removal and 4 eyes underwent BL retransplantation for incomplete re-epithelialization. One eye underwent BL regrafting 12 months postoperatively after traumatic corneal erosion. All eyes showed a completely re-epithelialized graft at the last available follow-up. CONCLUSIONS: BL onlay grafting is a completely extraocular, minimally invasive surgical technique, providing up to -6 D of corneal flattening in eyes with advanced progressive keratoconus, allowing for continued (scleral) contact lens wear and therefore preserving the BCLVA.

Tamarindus indica Extract as a Promising Antimicrobial and Antivirulence Therapy.

The worldwide crises from multi-drug-resistant (MDR) bacterial infections are pushing us to search for new alternative therapies. The renewed interest in medicinal plants has gained the attention of our research group. Tamarindus indica L. (T. indica) is one of the traditional medicines used for a wide range of diseases. Therefore, we evaluated the antimicrobial activities of ethanolic extract of T. indica. The inhibitions zones, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and fractional inhibitor concentration indices (FICI) against Gram+ve and -ve pathogens were detected. The bioactive compounds from T. indica extract were identified by mass spectroscopy, thin-layer chromatography, and bio-autographic assay. We performed scanning electron microscopy (SEM) and molecular docking studies to confirm possible mechanisms of actions and antivirulence activities, respectively. We found more promising antimicrobial activities against MDR pathogens with MIC and MBC values for Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa), i.e., (0.78, 3.12 mg/mL) and (1.56, 3.12 mg/mL), respectively. The antimicrobial activities of this extract were attributed to its capability to impair cell membrane permeability, inducing bacterial cell lysis, which was confirmed by the morphological changes observed under SEM. The synergistic interactions between this extract and commonly used antibiotics were confirmed (FICI values < 0.5). The bioactive compounds of this extract were bis (2-ethylhexyl)phthalate, phenol, 2,4-bis(1,1-dimethylethyl), 1,2-benzenedicarboxylic acid, and bis(8-methylnonyl) ester. Additionally, this extract showed antivirulence activities, especially against the S. aureus protease and P. aeruginosa elastase. In conclusion, we hope that pharmaceutical companies can utilize our findings to produce a new formulation of T. indica ethanolic extract with other antibiotics.

Correlation of internet search enquiries, incidence of ophthalmological diseases and corneal, cataract and refractive surgical procedures.

Analysis of internet search queries (ISQ) could be useful to study public interest and medical need for corneal, cataract, and refractive surgery. To date, there are preliminary data on seasonal trends in ophthalmic conditions, but only few studies correlate these data with real data from healthcare systems. The aim of this study is to analyze ISQ and correlate it with real healthcare system data. Data were retrieved from the KBV registry of patients who underwent outpatient ophthalmic surgery in Germany from 2017 to 2019 and from Statista GmbH from 2010 to 2020 for corneal refractive surgery. Time Series analysis of ISQ was analyzed from 2004 to 2020 and correlated with healthcare system data using bivariate correlation analysis. ISQ correlated significantly with the incidence of ophthalmic procedures such as corneal transplantations (r = 0.69, p < 0.05), cataract- (r = 0.59, p < 0.05) and refractive laser surgery (r = 0.83, p < 0.05) in Germany. In addition, specific trends were observed with respect to individual surgical procedures. The correlation between search intensities and surgical procedures varied significantly. Thus, interests in surgical procedures can be tracked by observing changes in ISQ over time. These data correlate with real healthcare data and could be used in the future for now-casting or even forecasting.

Prevalence of Helicobacter pylori infection in patients with chronic hepatitis C.

BACKGROUND: Association between Helicobacter pylori (H. pylori) and chronic hepatitis C (CHC) still remains controversial. This work is concerned with assessing the potential role of H. pylori in the progression of hepatitis C virus (HCV)-related chronic liver disease. RESULTS: A total of 449 individuals constituted this study (200 individuals were used to validate the assay while 249 individuals were used to assess the correlation between H. pylori infection and CHC). H. pylori antigen was quantified in serum samples using ELISA. As a consequence, our findings showed that H. pylori positivity was increased significantly (P = 0.021) with liver fibrosis progression as it was found in 44.45% of fibrotic patients and 71.88% of cirrhotic patients. We demonstrated that patients with F4 were accompanied by a significant (P < 0.05) increase in the concentration of H. pylori antigen displaying 16.52-fold and 1.34-fold increase in its level over F0 and F1-F3, respectively. Patients co-infected with H. pylori and HCV are 3.19 times (219%) more likely to experience cirrhosis than those who are mono-infected with HCV. This suggests that the risk for developing F4 was found to increase upon H. pylori co-infection when compared to CHC mono-infected patients. CONCLUSION: The elevated levels of H. pylori-antigen in HCV/H. pylori co-infection suggest increased susceptibility of co-infected patients for promoting hepatic fibrosis progression.

Alternative and Complementary Therapies against Foodborne Salmonella Infections.

The limitations in the therapeutic options for foodborne pathogens lead to treatments failure, especially for multidrug-resistant (MDR) Salmonella sp., worldwide. Therefore, we aimed to find alternative and complementary therapies against these resistant foodborne pathogens. Out of 100 meat products samples, the prevalence rate of salmonella was 6%, serotyped only as S. Typhimurium and S. Enteritidis. According to the antibiotic susceptibility assays, the majority of our isolates were MDR and susceptible to cefotaxime. Out of the 13 tested plant extracts, five only showed an inhibition zone in the range of 8-50 mm against both serotypes. Based on their promising activity, the oily extract of cinnamon and aqueous extract of paprika represented the highest potency. Surprisingly, a significant synergistic effect was detected between cinnamon oil and cefotaxime. Depending on Gas Chromatography/Mass Spectrometry (GC-MS), the antimicrobial activity of cinnamon oil was attributed to four components including linalool, camphor, (Z)-3-Phenylacrylaldehyde and its stereoisomer 2-Propenal-3-phenyl. The anti-virulence activities of these compounds were confirmed on the basis of computational molecular docking studies. Accordingly, we recommended the use of cinnamon oil as a food additive to fight the resistant foodborne pathogens. Additionally, we confirmed its therapeutic uses, especially when co-administrated with other antimicrobial agents.

New insights on plasters, pigments and binder in mural paintings of the Setka tomb (QH 110), Elephantine, Aswan, Upper Egypt.

Mural paintings within the tomb of Setka, Qubbet el-Hawa, in Aswan, Upper Egypt, were investigated using a multi-disciplinary analytical approach (Stereomicroscopy, SEM-EXD and FT-IR spectroscopy). The walls of the tomb were hewn from fragile sandstone and covered by a clay plaster, overlaid by two layers of white gypsum plaster. SEM micrographs were indicative of the penetration of fungal mycelium within the pores of the gypsum plaster, forming white encrustations due to the re-precipitation of gypsum. SEM micrographs revealed that the calcification of the gypsum plaster had occurred due to its exposure to a high temperature. The EDX pattern for the white plaster gave the characteristic spectrum of gypsum, the blue pigment was Egyptian blue, the black pigment was magnetite, the white pigment was of gypsum (or anhydrite) and the yellow pigment was limonite. Finally, the FT-IR spectrum of the binder gave the characteristic features of gum Arabic.

Evaluation of the Effectiveness of Soil Streptomyces Isolates for Induction of Plant Resistance Against Tomato mosaic virus (ToMV).

The ability of various Streptomyces isolates obtained from soil to induce systemic resistance in tomato (Solanum lycopersicum cv. Supra) plant against Tomato mosaic virus (ToMV) was characterized in current study. Importantly, of nine Streptomyces isolates tested herein, the culture filtrate (CF) of one isolate, designated as Streptomyces ovatisporus LC597360, was the most effective. It exhibited 93.9% biocontrol efficacy and induced a significant decrease (17.6 ± 0.8%) of symptoms severity compared with infected control plants. These finding were confirmed using I-ELISA showing that ToMV concentration was significantly reduced in plants treated with S. ovatisporus LC597360 CF as compared with plants inoculated with ToMV. Moreover, treatment with CF of S. ovatisporus LC597360 not only increased activity of defense-related enzymes such as ascorbate oxidase, catalase, peroxidase, and polyphenol oxidase, but also induced plant growth promotion. The present study is the first one that demonstrates the potential of S. ovatisporus LC597360 in biocontrol of ToMV and investigated its antiviral mechanisms.

Antibacterial activities of hexadecanoic acid methyl ester and green-synthesized silver nanoparticles against multidrug-resistant bacteria.

Antibacterial drug resistance is considered one of the biggest threats to human health worldwide, and the overuse of antibiotics accelerates this problem. Multidrug-resistant (MDR) bacteria are becoming harder to treat as the antibiotics used to treat them become less effective. Therefore, it is necessary to evaluate novel methods to control MDR bacteria. In this study, 40 bacterial isolates were collected from diabetic patients. The sensitivity of 40 bacterial isolates to seven antibiotics was evaluated. Four bacterial isolates were resistant to all antibiotic groups. The MDR pathogenic bacteria were selected and identified morphologically and biochemically and confirmed by VITEK® 2 system as follows: Staphylococcus aureus W35, Pseudomonas aeruginosa D31, Klebsiella pneumoniae DF30, and K. pneumoniae B40. Identification of the most resistant P. aeruginosa D31 was confirmed by the sequencing of a 16S ribosomal RNA gene with an accession number (MW241596). The inhibitory activity of eight types of native grown plant extracts against MDR bacteria was studied. Clove alcoholic extract (CAE) showed the highest inhibitory activity against MDR bacteria. Gas chromatography-mass spectrometry analysis of partially purified CAE at 0.9 Rf detected by thin-layer chromatography showed an active compound named hexadecenoic acid methyl ester with the highest antimicrobial effect against clinical pathogenic bacteria. The formation of silver nanoparticles (AgNPs) by CAE was studied. Evaluation of AgNPs was investigated by X-ray diffraction, UV-Vis, and transmission electron microscopy. The antibacterial effect of AgNPs after 2, 4, and 6 days in light and dark conditions was evaluated. Finally, the AgNPs synthesized using CAE possess good inhibition activity against the tested pathogenic bacteria. As a result, the bactericidal components listed above were promising in reducing MDR bacteria and can be used for treatments of bacterial infection and in the development of safe products with a natural base.

Inhibition of Staphylococcus aureus LC554891 by Moringa oleifera Seed Extract either Singly or in Combination with Antibiotics.

Bacterial outbreaks caused by Staphylococcus aureus (S. aureus) are interesting due to the existence of multidrug resistant (MDR) isolates. Therefore, there is a need to develop novel ways to control such MDR S. aureus. In this study, some natural agents such as honey bee (HB), extracts of either Moringa oleifera seeds (MSE), or leaves (MLE) and essential oils of garlic, clove, and moringa were studied for their inhibitory activity against this S. aureus pathogen. About 100 food samples including beef luncheon (n = 25), potato chips (n = 50), and corn flakes (n = 25) were investigated for possible pollution with the S. aureus bacteria. The isolated bacteria suspected to belong S. aureus that grew well onto Baird-Parker agar (Oxoid) and shiny halo zones and positive coagulase reaction were selected and identified by API-Kits; all of them that were approved belong to S. aureus (18 strains). The sensitivity of the obtained 18 S. aureus bacterial strains to 12 antibiotics were evaluated; all of them were resistant to ofloxacin; however, other antibiotics tested showed variable results. Interestingly, the S. aureus No. B3 isolated from beef luncheon was resistant to10 antibiotics out of 12 ones tested. Multiple antibiotic resistance index (MAR) of this S. aureus strain was about 83.3%. Therefore, its identification was confirmed by sequencing of a 16S rRNA gene which approved a successful biochemical identification carried out by API Kits and such strain was designated S. aureus LC 554891. The genome of such strain appeared to contain mecA gene encoding methicillin resistance; it was found to contain hla, hlb, tsst-1, and finbA that encode α-blood hemolysis, ß-blood hemolysis, toxic shock syndrome gene, and fibrinogen-binding protein gene, respectively. In addition, the virulence factors viz. sea; seb; sec encoding enterotoxins were detected in the DNA extracted from S. aureus B3 strain. Aqueous extract of Moringa oleifera seeds (MSE) showed inhibitory activity against S. aureus LC 554891 better than that obtained by tetracycline, essential oils or HB. Minimum inhibitory concentration (MIC) of MSE was 20µg/mL. Instrumental analysis of MSE showed 14 bioactive chemical compounds. Combinations of both MSE and tetracycline showed distinctive inhibitory activity against S. aureus LC 554891 than that obtained by either tetracycline or MSE singly.

Circulating levels of collagen III and MMP-1 in patients with chronic hepatitis C co-infected with hepatitis B virus.

BACKGROUND: There is controversial data in the literature about the characteristics and features of dual hepatitis B and hepatitis C infection. This work is concerned with estimating the extent to which HBV could influence circulating levels of hepatitis C viral nonstructural-4 (HCV-NS4) in addition to some direct fibrosis markers in chronic hepatitis C. METHODS: Thirty-eight HCV mono-infected and 87 HCV/HBV co-infected patients constituted this study. Western-blot and ELISA were used for identifying HCV-NS4, hepatitis B surface antigen (HBsAg), collagen III and matrixmetalloproteinase-1 (MMP-1) in patients' sera. RESULTS: Hepatitis B surface antigen (HBsAg) provided area under curve (AUC) of 0.97 for identifying HBV-patients with 89% sensitivity and 94% specificity, while HCV-NS4 antigen provided an AUC of 0.95 for identifying HCV-patients with 89% sensitivity and absolute specificity (100%). In general, patients with significant fibrosis (F2-F4) showed significantly higher concentration of collagen III (P = 0.009) and lower concentrations of MMP-1 (P = 0.007) when compared to patients with minimal fibrosis (F1). However, HCV/HBV co-infected patients with F1 and F2-F4 did not show any significant difference (P > 0.05) from HCV mono-infected patients with respect to HCV-NS4, collagen III and MMP-1. These results indicate that HBV does not influence the rate of HCV-NS4 synthesis and the deposition of extracellular matrix in HCV/HBV co-infected patients and subsequently does not affect the progression rates of hepatic fibrosis. CONCLUSION: HCV/HBV co-infected and HCV- mono-infected patients had similar clinical characteristics and there is no effect of HBV co-infection on the progression rates of liver fibrosis in chronic hepatitis C patients.

Sumatriptan succinate sublingual fast dissolving thin films: formulation and in vitro/in vivo evaluation.

Sumatriptan succinate (SS) is a 5-HT1 receptor agonist used in the treatment of migraine having poor bioavailability (15%) due to its extensive first-pass effect. The aim of this work was to prepare SS sublingual fast dissolving thin films (SFDTFs) allowing the drug to directly enter the systemic circulation and bypassing the first-pass metabolism. Plain thin films were prepared using solvent casting technique adopting 2(3) × 3 factorial design to study the effect of polymer and plasticizer type and concentration on mechanical properties and in vitro disintegration time of the plain prepared films using Design-Expert®. Medicated films were prepared after addition of 35 mg SS to each of the two selected plain formulae (F6 and F7) having desirability values above 0.9 showing the values of: 0.038, 0.039 kgf/mm(2) and 156.24, 164.16% and 0.0248, 0.0240 kgf/mm(2) as tensile strength, percent elongation and elastic modulus, respectively. PVP K30 was efficient as crystallization inhibitor in retarding SS crystallization. Pharmacokinetic study of the optimum formula F7 (PVP K30:SS (1:1 w/w)) in healthy human volunteers using LC/MS/MS revealed a shorter tmax (0.25 h) compared to Imitrex® tablet 25 mg (2 h) which is considered promising especially for the rapid relief of acute migraine attacks.

Perinatal transmission of hepatitis C antigens: envelope 1, envelope 2 and non-structural 4.

BACKGROUND: Perinatal exposure to hepatitis C virus (HCV) antigens during pregnancy may affect the developing immune system in the fetus. We aimed to study the perinatal transmission of HCV structural and non-structural antigens. METHODS: Sera from 402 pregnant mothers were tested for anti-HCV antibody and HCV RNA. HCV antigens were determined in sera from 101 HCV-infected mothers and their cord blood. RESULTS: In both serum and cord blood samples, HCV NS4 (non-structural 4) at 27 kDa, E1 (envelope 1) at 38 kDa and E2 (envelope 2) at 40 kDa were identified, purified and quantified using western blotting, electroelution and ELISA. Maternal sera and neonate cord blood samples had similar detection rates for NS4 (94.1%), E1 (90.1%) and E2 (90.1%). The mean maternal serum levels (optical density, OD) of HCV NS4 (0.87 ± 0.01), E1 (0.86 ± 0.01) and E2 (0.85 ± 0.01) did not differ significantly (p > 0.05) from those of neonatal cord blood (0.83 ± 0.01, 0.87 ± 0.01 and 0.85 ± 0.01, respectively). Also, strong correlations (p < 0.0001) were shown between sera and cord blood sample levels of HCV NS4, r = 0.77; E1, r = 0.76 and E2, r = 0.80. The vertical transmission of these antigens in vaginal delivery did not differ significantly (p > 0.05) from those in caesarean section. CONCLUSIONS: These findings indicate that vertical transmission of HCV NS4, E1 and E2 antigens was very high. Thus, exposure to these antigens may influence the developing immune responses to natural infection or future vaccination.

Diagnostic performances of hepatitis C virus-NS4 antigen in patients with different liver pathologies.

BACKGROUND AND AIMS: Hepatitis C virus (HCV) has emerged as the major pathogen of liver disease worldwide. The aim of this study was to quantitate and evaluate the performance of HCV-NS4 antigen as an alternative approach for confirmation of viremia. METHODS: Detection of HCV-NS4 was assessed in 883 patients with chronic hepatitis C. Areas under the ROC curves (AUC) were used to assess and compare diagnostic accuracy of ELISA for HCV-NS4 with quantitative HCV-RNA as a gold standard. RESULTS: HCV-NS4 was identified at 27 kDa using Western blot. AUC for HCV-NS4 detection was 0.95 for all patients with different liver pathologies: 0.93 for liver fibrosis (LF), 0.95 for liver cirrhosis (LC) and 0.98 for hepatocellular carcinoma (HCC). The mean ± SD (µg/mL) of HCV-NS4 in LF was 94.2 ± 55.6; in LC was 99.3 ± 64.8 and in HCC was 124.9 ± 70.3. CONCLUSIONS: HCV-NS4 antigen detection using ELISA is a reliable test in the confirmation of HCV infection.

A new sequence for single-shot diffusion-weighted NMR spectroscopy by the trace of the diffusion tensor.

Diffusion-weighted spectroscopy is a unique tool for exploring the intracellular microenvironment in vivo. In living systems, diffusion may be anisotropic, when biological membranes exhibit particular orientation patterns. In this work, a volume selective diffusion-weighted sequence is proposed, allowing single-shot measurement of the trace of the diffusion tensor, which does not depend on tissue anisotropy. With this sequence, the minimal echo time is only three times the diffusion time. In addition, cross-terms between diffusion gradients and other gradients are cancelled out. An adiabatic version, similar to localization by adiabatic selective refocusing sequence, is then derived, providing partial immunity against cross-terms. Proof of concept is performed ex vivo on chicken skeletal muscle by varying tissue orientation and intra-voxel shim. In vivo performance of the sequence is finally illustrated in a U87 glioblastoma mouse model, allowing the measurement of the trace apparent diffusion coefficient for six metabolites, including J-modulated metabolites. Although measurement performed along three separate orthogonal directions would bring similar accuracy on trace apparent diffusion coefficient under ideal conditions, the method described here should be useful for probing intimate properties of the cells with minimal experimental bias.

High sensitivity 19F MRI of a perfluorooctyl bromide emulsion: application to a dynamic biodistribution study and oxygen tension mapping in the mouse liver and spleen.

We have recently developed an optimized multi-spin echo (MSE) sequence dedicated to perfluorooctyl bromide (PFOB) imaging yielding an excellent sensitivity in vitro. The aim of the present study was to apply this sequence to quantitative measurements in the mouse liver and spleen after intravenous (i.v.) injection of PFOB emulsions. We first performed oxygenation maps 25.5 min after a single infusion of emulsion and, contrary to previous studies, shortly after injection. The signal-to-noise ratio (SNR) in the liver and spleen was as high as 45 and 120, respectively, for 3-min images with 11.7-µL pixels. Values of oxygen tension tended to be slightly higher in the spleen than in the liver. Dynamic biodistribution experiments were then performed immediately after intravenous (i.v.) injection of PFOB emulsions grafted with different quantities of polyethylene glycol (PEG) for stealth. Images were acquired every 7 min for 84 min and the SNR measured in the liver and spleen was at least four from the first time point. Uptake rates could be assessed for each PEG amount and, in spite of high standard deviations (SDs) owing to interanimal variability, our data confirmed that increasing quantities of PEG allow more gradual uptake of the emulsion particles by the liver and spleen. In conclusion, our method seems to be a powerful tool to non-invasively perform accurate in vivo quantitative measurements in the liver and spleen using (19)F MRI.

Milk kefir: ultrastructure, antimicrobial activity and efficacy on aflatoxin B1 production by Aspergillus flavus.

The association of kefir microbiota was observed by electron microscopic examination. Scanning electron microscopic (SEM) observations revealed that kefir grain surface is very rough and the inner portions had scattered irregular holes on its surface. The interior of the grain comprised fibrillar materials which were interpreted as protein, lipid and a soluble polysaccharide, the kefiran complex that surrounds yeast and bacteria in the grain. Yeast was observed more clearly than bacteria on the outer portion of the grain. Transmission electron microscopic (TEM) observations of kefir revealed that the grain comprised a mixed culture of yeast and bacteria growing in close association with each other. Microbiota is dominated by budded and long-flattened yeast cells growing together with lactobacilli and lactococci bacteria. Bacterial cells with rounded ends were also observed in this mixed culture. Kefir grains, kefir suspensions, and kefiran were tested for antimicrobial activities against several bacterial and fungal species. The highest activity was obtained against Streptococcus faecalis KR6 and Fusarium graminearum CZ1. Growth of Aspergillus flavus AH3 producing for aflatoxin B1 for 10 days in broth medium supplemented with varying concentrations of kefir filtrate (%, v/v) showed that sporulation was completely inhibited at the higher concentrations of kefir filtrate (7-10%, v/v). The average values of both mycelial dry weights and aflatoxin B1 were completely inhibited at 10% (v/v). This is the first in vitro study about the antifungal characteristics of kefir against filamentous fungi which was manifested by applying its inhibitory effect on the productivity of aflatoxin B1 by A. flavus AH3.