Coccidioidomycosis
Rebecca A. Cox in Immunology of the Fungal Diseases, 2020
The mold colony cultured from patients with coccidioidomycosis and the sporangia-like form observed in tissues represent the mycelial and spherule/endospore phases of C. immitis. In its saprobic form, the fungus exists in soil in the semi-arid regions of the Western Hemisphere, in an area extending from California to Argentina.8, 9 Endemic areas within the U.S. include parts of California, Arizona, Nevada, Utah, New Mexico, and Texas, which correspond to the Lower Sonoran Life Zone. The mycelia propagate by the formation of alternating enterothallic arthroconidia (previously designated arthrospores).10–12 These infectious arthroconidia (measuring 2 to 5 µm in length) are released by disintegration of the adjacent sterile cells and become airborne. Within host tissue, the arthroconidia transform into round cells that progressively enlarge with concomitant nuclear replication. These immature spherules undergo an internal segmentation process that leads to the formation of endospores. At maturity, the spherules (measuring up to 60 µm in diameter) rupture, releasing numerous endospores which then repeat the parasitic phase.11–13 This multiphasic, morphogenetic cycle (depicted in Figure 1) is unique among the pathogenic fungi and, by virtue of cell size and antigenic variance,14–18 presents a formidable challenge to the host’s immunologic armory.
Cutaneous Manifestations of Deep Fungal Infections in HIV Disease
Clay J. Cockerell, Antoanella Calame in Cutaneous Manifestations of HIV Disease, 2012
C. immitis is a dimorphic fungus. The mycelial form represents the saprobic (environmental) phase which grows in soil of endemic regions. It forms the branching septate hyphae from which arthroconidia develop. Mature arthroconidia become stable and easily airborne. Once inhaled by humans or animals, the fungus changes into its parasitic (tissue) phase. When it reaches the bronchiole, the arthroconidium converts into a multinucleate spherical structure (spherule). The spherule undergoes internal division to produce hundreds of uninucleate endospores. Endospores are released once the spherule matures; those that remain in tissue are each capable of forming new spherules. Once released into the environment, they develop into the mycelial form.60
Basic Microbiology
Philip A. Geis in Cosmetic Microbiology, 2020
Endospore—In a few genera, bacteria can internally generate this protective structure by a process termed “sporulation” usually induced by unfavorable conditions. The endospore is an environmentally resistant, metabolically inert structure which contains, at the least, the bacterial DNA, some proteins, calcium, and dipicolinic acid. Upon the return of favorable conditions, the endospore can reproduce the growing form of the bacteria by “vegetation” or outgrowth. Few genera contain spore-forming bacteria, most notably the Clostridium and Bacillus genera form spores.
Visualizing germination of microbiota endospores in the mammalian gut
Published in Gut Microbes, 2022
Ningning Xu, Liyuan Lin, Yahui Du, Huibin Lin, Jia Song, Chaoyong Yang, Wei Wang
Many Gram-positive bacteria propagate by forming and spreading endospores. Recalcitrant to desiccation and most disinfectants, the production of endospores permits long-term survival of the microbes in hostile environments.1,2 Bacterial sporulation is initiated by an asymmetric cell division through the formation of a polar septum; after this prespore is engulfed by the mother cell, several durable proteinaceous layers are then assembled onto the forespore surface,3 which protect them from being lyzed by enzymes. The forespore then matures after its chromosome is saturated with small, acid-soluble proteins and cytoplasm partially dehydrated, enabling endospores’ resistance to UV radiation and heat. The mature endospores can then be released, and ubiquitously found in soil, water, air and almost all human surroundings.4–6 People can unintentionally inhale or ingest endospores, and their germination into vegetative bacteria in the respiratory or gastrointestinal tracts can profoundly affect our health.
Effect of bacterial toxin identified from the Bacillus subtilis against the Cnaphalocrocis medinalis Guenée (Lepidoptera: Crambidae)
Published in Toxin Reviews, 2023
Ramakrishnan Ramasubramanian, Sengodan Karthi, Sengottayan Senthil-Nathan, Haridoss Sivanesh, Narayanan Shyam Sundar, Vethamonickam Stanley-Raja, Govindaraju Ramkumar, Kanagaraj Muthu-Pandian Chanthini, Prabhakaran Vasantha-Srinivasan, Khaloud Mohammed Alarjani, Mohamed S Elshikh, Ahmed Abdel-Megeed, Patcharin Krutmuang
Entomopathogenic bacterial spores can be effective against insect pests and act as bacterial pesticides. Research continues to demonstrate the application of bacterial-based insecticides against a wide range of insect pests across many cropping systems (Usta 2013, Ruiu 2015). Almost all groups of microbes which include fungi, bacteria, yeast and viruses have members with the potential to produce toxins that can significantly suppress insect survival (Kumari et al. 2014, Chalivendra 2021). The genome B. subtilis encrypts ten chemoreceptors recognized as ligands, which are composed of carbon, amino acids, and oxygen (Hashem et al. 2019). Species of Bacillus generally make endospores to endure under environmental conditions. Spores permit long-term storage of biological control agents and can be delivered using a variety of formulations (Hashem et al. 2019). In general, strains of Bacillus have been shown to produce a natural blend of bio-active metabolites that are effective in controlling insect pests of plants and diseases caused by plant pathogens (Asaka and Shoda 1996, Ghribi et al. 2012). The present study reported on the detrimental effects of B. subtilis on larval stages of C. medinalis when ingested with treated rice leaves.
Endemic pulmonary fungal diseases in immunocompetent patients: an emphasis on thoracic imaging
Published in Expert Review of Respiratory Medicine, 2019
Ana Luiza Di Mango, Gláucia Zanetti, Diana Penha, Miriam Menna Barreto, Edson Marchiori
Coccidioides species exist as a mycelial forms 10–30 cm beneath the soil and prefer areas with mild winters, lower amounts of rainfall and alkaline soils. During the dry period, these forms desiccate and release arthroconidia, the highly infectious spore forms of Coccidioides. The infection is caused by inhalation of these spores aerosolized when the soil is disrupted [24–27]. Wind and sandstorms, earthquakes, construction workers, excavation, agriculture, and archeological activities have been associated with epidemics in endemics areas caused by significant soil disruption [23–26]. Armadillo hunting, notably in the north-eastern of Brazil, has also been reported in the literature [28]. When airborne arthroconidia are inhaled, the lung is the primary site of infection, where they transform into spherules that eventually rupture releasing hundreds to thousands of endospores. A granulocytic response occurs and, as it progress, a granuloma containing histiocytes and giant cells are formed. Endospores spread hematogenously or by the lymphatics into any organ, propagating the cycle [24].
Related Knowledge Centers
- Bacillus Anthracis
- Bacillus Cereus
- Bacillus Thuringiensis
- Bacteria
- Dormancy
- Spore
- Bacillota
- Gram-Positive Bacteria
- Virgibacillus Marismortui
- Species