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Dermatophytosis
Published in Rebecca A. Cox, Immunology of the Fungal Diseases, 2020
There are at least 40 species recognized by taxonomists in the three genera of dermatophytes. These species appear to be relatively similar microbiologically, although they can be differentiated on the basis of colonial morphology, microscopic appearance (particularly the structure of macroconidia and microconidia), and some biochemical tests. The many species of dermatophytes have certain other differences, including their reservoirs, the cutaneous sites usually infected, the degree of inflammation generally produced, and the chronicity of their infections. An unusual and important characteristic of this group of microorganisms is their ability to digest keratin. They can therefore infect the stratum corneum, hair, and nails using keratin as a source of nutrients.
Patulin
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
Alejandro Hernández, Alicia Rodríguez, Santiago Ruiz-Moyano, Francisco Pérez-Nevado, Juan J. Córdoba, Alberto Martín
The influence of temperature and oxygen levels over growth and patulin production has been analyzed in several studies. Baert et al. [30] in an in vitro study, with different strains of P. expansum proved that optimal growth conditions were different than optimal patulin production conditions. Temperature has a strong influence in its growth; in all cases, an optimal growth was observed at 25°C. On the contrary, although patulin can be produced at temperatures between 1°C and 25°C, the effect of temperature over the production is not so clear and seems to depend on the strain. In most studies, a decrease in patulin concentrations at lower temperatures was observed. Salomão et al. [42] found patulin production in apples stored at 20.5°C and 11°C, but patulin concentrations were significantly higher at 20.5°C. Other studies reported higher patulin production at 17°C, 20°C, or 25°C than at 1°C or 4°C. Tannous et al. [36] obtained the highest concentrations of patulin at 16°C, in concordance with the findings of Paster et al. [39], but in contrast to those of McCallum et al. [40]. However, Baert et al. [30] noted that patulin production was stimulated by a temperature change from 10°C to 4°C, although this finding was strain dependent. These authors recommended storing apples at a temperature of 1°C; this temperature is suitable to reduce the growth of the mold and to avoid patulin formation. Moreover, Tannous et al. [36] observed a variation in the colonial morphology and color of a P. expansum strain under different testing temperatures (from 8°C to 30°C), which could be linked to stress response.
The Microbiology Laboratory
Published in Keith Struthers, Clinical Microbiology, 2017
Two different coliforms growing on CLED agar, each having a distinct colonial morphology, are shown in Figure 5.7. Single colonies can be ‘picked off’ to determine the identity of the organism and its antibiotic susceptibility profile. In the following sections, basic tests are discussed, as well as the rapid identification MALDI-TOF machine.
Development of a multiplex two-gene real-time PCR assay for accurate detection of Klebsiella pneumoniae
Published in British Journal of Biomedical Science, 2019
Y Dou, L Li, J Du, Y He, R Chen, Y Li, C Ma, H Liu
Ninety-five K. pneumoniae local isolates were randomly selected as positive controls, whilst 95 local isolates commonly found in the lower respiratory tract as pathogens were negative controls. The latter include Streptococcus pneumoniae, Haemophilus influenza, Staphyloccoccus aureus, Moraxella catarrhalis, Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii. All positive and negative control strains were isolated from respiratory samples and were characterized by colonial morphology, standard biochemical methods and VITEK-2 (bioMerieux, Basingstoke, UK). A total of 2754 sputum specimens were collected from patients with suspected lower respiratory tract infections between January 2015 and December 2016 following routine microbiological culture. Specimens with >25 white blood cells per high-power field and <10 squamous cell per high-power field through Gram smear detection were accepted. Ethical committee approval and informed consent from all participants were obtained.
Fractional carbon dioxide laser assisted delivery of topical tazarotene versus topical tioconazole in the treatment of onychomycosis
Published in Journal of Dermatological Treatment, 2019
Essam Bakr Abd El-Aal, Hamed Mohamed Abdo, Shady Mahmoud Ibrahim, Mostafa Taha Eldestawy
The fungi were identified by noting their growth rate, colonial morphology, and microscopic structures. Colonial morphology includes color, size, texture, and topography of the colony. The microscopic structures of fungi usually provide definitive identification. Microscopic features that were looked for are the type, size, shape, and arrangement of spores and the size and color of hyphae.