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Infections
Published in Evelyne Jacqz-Aigrain, Imti Choonara, Paediatric Clinical Pharmacology, 2021
Evelyne Jacqz-Aigrain, Imti Choonara
Escherichia coli cause 80 to 90% of UTIs in children. They are so called primary pathogens for the urinary tract. Most of the E. coli that cause acute pyelonephritis carry virulence factors that facilitate invasion of the urinary tract and initiate an inflammatory host response [6]. Capacity to adhere to uroepithelial cells is the virulence factor that is most characteristic of E. coli strains capable of inducing pyelonephritis. These strains often carry several adhesins, but the most important type is so called P-fimbriae. These favour colonisation of the large intestine that is the major reservoir for bacteria that enter the urinary tract by ascending up through the urethra, and bind to specific receptors on uroepithelial cells. This binding activates a cytokine cascade, leading to a local and systemic inflammatory response [7]. It is the extent and severity of the inflammatory reaction in the kidney that determines if the patient will develop permanent renal damage (renal scarring) or if the inflammation will heal without sequelae [6].
Epidemiology of Acinetobacter spp.: Surveillance and Management of Outbreaks
Published in E. Bergogne-Bénézin, M.L. Joly-Guillou, K.J. Towner, Acinetobacter, 2020
M.-L. Joly-Guillou, C. Brun-Buisson
Fimbriae — >Thin fimbriae about 3 nm in diameter and thick fim-briae about 5 nm in diameter have been observed in Acinetobacter spp. by Henriksen and Blom (1975). Whereas the presence of thick fimbriae has been correlated with twitching motility, thin fimbriae are associated with adherence to hydrocarbons (Rosenberg et al., 1982; Pines and Gutnick, 1984). The presence of fimbriae has been linked to pathogenesis in various strains, attesting to the importance of bacterial adherence for colonisation of host tissues.
Control of the Large Bowel Microflora
Published in Michael J. Hill, Philip D. Marsh, Human Microbial Ecology, 2020
Bohumil S. Drasar, April K. Roberts
As implied above, infants can only be colonized by the bacteria to which they are exposed, and those organisms that persist are capable of forming relatively permanent communities on the gut mucus surface. Many organisms produce a glycocalyx that acts as an anchor for the organism. Bacteria such as Escherichia coli produce fimbriae that extend from the cell wall and may act as specific adhesions anchoring the cell to the mucus layer. The glycocalyx also provides a local protected environment for bacterial growth, allowing multiplication and helping the formation of microcolonies. The glycocalyxes of several different organisms may intermingle to form a diverse community which is in effect co-operatively attached to the mucosa.28 Thus, for initial colonization, attachment/adhesion must be among the predominant influences. The role of metabolic end products and diet is more important in the later stages of community development.
Structural and antigenic characterization of a novel genotype of Mfa1 fimbriae in Porphyromonas gingivalis
Published in Journal of Oral Microbiology, 2023
Miyuna Fujimoto, Yoshikazu Naiki, Kotaro Sakae, Tomohiko Iwase, Naoyoshi Miwa, Keiji Nagano, Hiroyuki Nawa, Yoshiaki Hasegawa
P. gingivalis expresses various virulence factors, including proteases (gingipains), lipopolysaccharides, and most notably, fimbriae [8], which form a multi-species biofilm that colonizes periodontal tissues [9]. At least two distinct types of fimbriae are expressed in the bacterium, namely FimA and Mfa1 fimbriae [9]. The Mfa1 fimbria mainly comprises Mfa1 protein polymers encoded by mfa1 in the mfa gene cluster [9]. Mature fimbriae also contain the minor proteins Mfa2–5, encoded downstream of mfa1 (Figure S1) [10]. Mfa2 is localized in the basal portion of the structure and functions as an anchor and elongation terminator [11,12]. We previously reported that Mfa3 and Mfa4 were detected in purified fimbriae as 40 and 30 kDa bands, respectively, in a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) gel, and Mfa5 was detected as two bands, 130 and 150 kDa. Mfa3, Mfa4, and Mfa5 participate in the assembly of accessory protein complexes on the tips of fimbriae [13–15]. Recent structural and mechanistic analyses of the fimbrial proteins of P. gingivalis have revealed that the Mfa1–4 proteins are polymerized by a proteinase-mediated donor strand exchange mechanism, which is classified as a novel type of fimbriae designated as type V fimbriae [16,17]. The precursor of Mfa1 in P. gingivalis, the ATCC 33,277 strain, is cleaved for maturation at Arg49, located at the N-terminus via gingipains [18]. Additionally, Mfa1 fimbriae have recently been reported to modulate innate immune responses [19,20].
Chronic canaliculitis with canaliculoliths due to Providencia stuartii infection
Published in Orbit, 2023
Jenny Lin, Victoria S. North, Christopher Starr, Kyle J. Godfrey
To the best knowledge of the authors, this represents the first reported case of canaliculitis caused by P. stuartii. Providencia stuartii is a gram-negative bacillus of the Morganellaceae family commonly found in soil, water, and animal reservoirs.5 It has been described as an opportunistic pathogen in hospitalized patients and is associated with urinary tract infections in patients with indwelling catheters due to fimbriae that allow for adherence.6 It can grow in anaerobic environments and notably produces urease, which plays an important role in the pathogenesis of urolithiasis and urinary tract infections.5,6 Bacterial urease catalyzes the hydrolysis of urea to form ammonia and carbon dioxide, producing alkaline urine that serves as a favorable environment for the formation of urinary tract stones.5,6 Urea is also found in the lacrimal glands, providing a possible mechanism for the formation of canalicular stones described in the present case.7
Salmonella enterica subsp. II serovar 4,5,12:a:- may cause gastroenteritis infections in humans
Published in Gut Microbes, 2022
Meiying Yan, Yongming Zhou, Yang Cao, Zhenpeng Li, Xin Lu, Bo Pang, Shukun Wang, Biao Kan
Fimbriae and pili play central roles in bacterial adherence and colonization.34 The genome sequences of the S. 4,5,12:a:- isolates revealed the presence of several universal SPIs, including intact SPI-1 and SPI-2, and the majority of effectors translocated in the two systems, indicating that S. 4,5,12:a:- has two functionally distinct T3SSs that enable the invasion of epithelial cells by bacteria and facilitate the replication of bacteria within macrophages. This hypothesis was confirmed by the cell invasion tests in Caco-2, HeLa and macrophage cells, and competition assays and mouse infection models in this study. In addition to virulence genes, a fimH allele, famH80, which has recently been identified as human-prone and human-specific,35 was also found in this serovar. Furthermore, we found that the S. 4,5,12:a:- strains harbored an LEE locus, which was previously observed to be specific to S. salamae.21 All of these characteristics illustrate that S. salamae shares some genetic characteristics with E. coli, especially those related to extracellular pathogenicity. Additionally, it was demonstrated that 4,5,12:a:- belongs to subspecies II, not I. All of the above factors may play roles in the pathogenicity and/or in the invasive characteristics of S. 4,5,12:a:-, possibly by contributing to tissue tropism and/or colonization.