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Periodontitis affects oral tissues and induces systemic inflammation, which increases the risk of cardiovascular disease and metabolic syndrome. Subgingival plaque accumulation is a trigger of periodontitis. Fusobacterium nucleatum (FN) contributes to subgingival biofilm complexity by intercalating with early and late bacterial colonizers on tooth surfaces. In addition, inflammatory responses to FN are associated with the progression of periodontitis. Nigella sativa Lin. seed, which is known as black cumin (BC), has been used as a herbal medicine to treat ailments such as asthma and infectious diseases. The current study examined the inhibitory effect of BC oil and its active constituents, thymol (TM) and thymoquinone (TQ), on FN‑associated biofilm and inflammation. FN‑containing biofilms were prepared by co‑cultivation with an early dental colonizer, Actinomyces naeslundii (AN). The stability and biomass of FN/AN dual species biofilms were significantly higher compared with FN alone. This effect was retained even with prefixed cells, indicating that FN/AN co‑aggregation is mediated by physicochemical interactions with cell surface molecules. FN/AN biofilm formation was significantly inhibited by 0.1% TM or TQ. Confocal laser scanning microscopy indicated that treatment of preformed FN/AN biofilm with 0.01% of BC, TM or TQ significantly reduced biofilm thickness, and TQ demonstrated a cleansing effect equivalent to that of isopropyl methylphenol. TQ dose‑dependently suppressed TNF‑α production from a human monocytic cell line, THP‑1 exposed to FN, yet showed no toxicity to THP‑1 cells. These results indicated that oral hygiene care using TQ could reduce FN‑associated biofilm and inflammation in gingival tissue.

Otomycosis is a fungal infection of the external auditory canal caused mainly by the genus Aspergillus. Aspergillus luchuensis, an industrially important fungus, is a member of Aspergillus section Nigri. In this report, we present a case of otomycosis due to Aspergillus luchuensis in a 43-year-old female patient. We performed a partial PCR-sequencing of β-tubulin and calmodulin genes to identify the isolate to the species level. Further, we determined the in vitro susceptibility of the isolate to nystatin, clotrimazole and itraconazole according to the Clinical & Laboratory Standards Institute (CLSI) M38-A2 protocol. Accordingly, the minimum inhibitory concentrations of clotrimazole, nystatin and itraconazole were 0.25μg/mL, 0.5μg/mL and 1μg/mL, respectively. This is the first report of clinically relevant isolation of Aspergillus luchuensis identified by a molecular technique as a causative agent of otomycosis.

The human gut commensal Bacteroides fragilis produces sialidases that remove a terminal sialic acid from host-derived polysaccharides. Sialidase is considered to be involved in B. fragilis infection pathology. A native B. fragilis sialidase has been purified and characterized, and was shown to be post-translationally modified by glycosylation. However, the biochemical properties of recombinant B. fragilis sialidase expressed in a heterologous host remain uncharacterized. In this study, we examined the enzymatic properties of the 60-kDa sialidase NanH1 of B. fragilis YCH46, which was prepared as a recombinant protein (rNanH1) in Escherichia coli. In E. coli rNanH1 was expressed as inclusion bodies, which were separated from soluble proteins to allow solubilization of insoluble rNanH1 in a buffer containing 8 M urea and renaturation in refolding buffer containing 100 mM CaCl2 and 50 mM L-arginine. The specific activity of renatured rNanH1 measured using 4-methylumberiferyl-α-D-N-acetyl neuraminic acid as a substrate was 6.16 μmol/min/mg. The optimal pH of rNanH1 ranged from 5.0 to 5.5. The specific activity of rNanH1 was enhanced in the presence of calcium ions. rNanH1 preferentially hydrolyzed the sialyl α2,8 linkage and cleaved sialic acids from mucin and serum proteins (e.g., fetuin and transferrin) but not from α1-acid glycoprotein, which is similar to the previously observed biochemical properties for a native sialidase purified from B. fragilis SBT3182. The results and methods described in this study will be useful for preparing and characterizing recombinant proteins for other B. fragilis sialidase isoenzymes.

Background: Otomycosis is a superficial infection of the ear caused by a spectrum of various fungal agents and its epidemiology depends on geographical region and climatic condition. The aim of this study was to investigate the causal agents and clinical manifestations of otomycosis at a tertiary referral center in Tehran, Iran. Methods: From Apr 2016 to Jan 2017 a set of 412 subjects with suspicion of external otitis were included. Clinical examination and specimen collection were performed by an otorhinolaryngologist. Subsequently, direct examination and culture were performed on specimens and isolated molds were identified morphologically. Yeast isolates were identified using CHROMagar Candida medium and PCR-RFLP of ribosomal DNA whenever needed. Data were analyzed using SPSS. Results: Otomycosis was confirmed in 117 cases (28.39%) including 64 (54.7%) males and 53 (45.3%) females. Patients were within the age range of 10-75 yr and the highest prevalence was found in the age group of 46-55 yr (30.77%). Pruritus (89.74%) and auditory manipulation and trauma (83.76%) were the predominant symptom and predisposing factor, respectively. Among 133 isolates from 117 patients, Aspergillus niger (n=50, 37.59%) was the most common etiologic agent and Candida glabrata (n=25, 18.8%) was the predominantly isolated yeast. Furthermore, 16 cases of mixed infection were identified and coinfection due to A. niger and C. glabrata (seven cases) was the predominant pattern. Conclusion: Our results revealed the high prevalence of C. glabrata and mixed infections in otomycosis patients. Therefore, mycological examinations should be considered for proper treatment.

Background: Otitis externa is an inflammatory in external auditory canal, with the presentation of otalgia, otorrhea, and pruritus. Bacteria and fungi are the most causative agents of the disease. Although several antifungal and antibacterial agents are usually used to treat it, combination therapy plays an important role in good treatment efficacy. Objectives: According to the problems associated with the treatment of mixed otitis externa, the current study aimed at evaluating the efficacy of ceftazidime powder and topical miconazole (as the case group) versus topical miconazole only (as the control group) to treat mixed otitis externa. Methods: Seventy-two patients with mixed otitis externa were divided into two groups; the case group was treated with ceftazidime powder and topical miconazole, and the control group was treated only with topical miconazole. Both groups were evaluated after two weeks. The diagnosis of mixed otitis externa was based on signs, symptoms, and the presence of bacterial and fungal elements in direct examination and culture. Results: Swelling, itching, and canal discharge were observed in 67.7%, 64.7%, and 90.3% of the patients, respectively in the case group, and 47.1%, 26.3% and 93.1% of the patients, respectively in the control group. Complete resolution of all clinical signs and symptoms occurred in 23 (67.6%) patients in the case group and 11 (28.9%) patients in the control group (P = 0.001). Staphylococcus epidermidis and Pseudomonas aeruginosa were the most common bacteria, and Aspergillus spp. and Candida spp. were the most common fungi identified in the cultures. Conclusions: According to the complete resolution of clinical signs, the application of ceftazidime powder and topical miconazole was better than topical miconazole to treat mixed otitis externa.

Introduction Aspergillus niger is the most commonly reported etiology of otomycosis based on morphological characteristics. This fungus is a member of Aspergillus section Nigri, a set of morphologically indistinguishable species that can harbor various antifungal susceptibility patterns. The aim of this study was to accurately identify and determine the susceptibility pattern of a set of black aspergilli isolated from otomycosis patients. Methods Forty-three black Aspergillus isolates from otomycosis patients were identified by using the PCR-sequencing of the β-tubulin gene. Furthermore, the susceptibility of isolates to three antifungal drugs, including fluconazole (FLU), clotrimazole (CLT) and nystatin (NS), were tested according to CLSI M38-A2. The data were analyzed using the SPSS software (version 15). Results The majority of isolates were identified as A. tubingensis (32/43, 74.42%) followed by A. niger (11/43, 25.58%). The lowest minimum inhibitory concentration (MIC) values were observed for NS with geometric means (GM) of 4.65 μg/mL and 4.83 μg/mL against A. tubingensis and A. niger isolates, respectively. CLT showed wide MIC ranges and a statistically significant inter-species difference was observed between A. tubingensis and A. niger isolates (P 64 μg/mL. Conclusion Species other than A. niger can be more frequent as observed in our study. In addition, considering the low and variable activity of tested antifungal drugs, empirical treatment can result in treatment failure. Accurate identification and antifungal susceptibility testing of isolates is, however, recommended.

Excessive damage to DNA and lipid membranes by reactive oxygen species reduces the viability of bacteria. In the present study, the proliferation of recA‑deficient Escherichia coli strains was revealed to be inhibited by 1% L‑histidine under aerobic conditions. This inhibition of proliferation was not observed under anaerobic conditions, indicating that L‑histidine enhances oxidative DNA damage to E. coli cells. Reverse transcription‑quantitative polymerase chain reaction analysis demonstrated that the expression of recA in E. coli MG1655 increased ~7‑fold following treatment with 10 mM hydrogen peroxide (H2O2) plus 1% L‑histidine, compared with that following exposure to H2O2 alone. L‑histidine increased the genomic fragmentation of E. coli MG1655 following exposure to H2O2. In addition, L‑histidine increased the generation of intracellular hydroxyl radicals in the presence of H2O2 in E. coli cells. Next, our group investigated the disinfection properties of the H2O2 and L‑histidine combination. The combination of 100 mM H2O2 and 1.0% L‑histidine significantly reduced the number of viable cells of extended‑spectrum‑β‑lactamase‑producing E. coli and multidrug‑resistant Pseudomonas aeruginosa, and this treatment was more effective than 100 mM H2O2 alone, but this effect was not observed in methicillin‑resistant Staphylococcus aureus or vancomycin‑resistant Enterococcus faecium. The combination of L‑histidine and H2O2 may be a useful strategy to selectively increase the microbicidal activity of oxidative agents against Gram‑negative bacteria.