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Anthrax
Published in Meera Chand, John Holton, Case Studies in Infection Control, 2018
B. anthracis is a rod-shaped, Gram-positive, aerobic bacterium that readily grows on standard microbiological media. The typical colony at 24 hours of growth in air or 5% CO2 is grey to white, nonhemolytic on blood agar, with a dry, ground-glass appearance. The colony may be distinguishable by the presence of swirling projections (commonly known as Medusa head appearance). Encapsulated colonies may be mucoid. In vivo, bacterial cells often grow in long chains that resemble bamboo. PCR or immunofluorescence tests may be used to distinguish B. anthracis from related bacteria.
Validation of methods
Published in Philip A. Geis, Cosmetic Microbiology, 2006
The most common standard in microbiological laboratory operations is the one for making microbiological media in an autoclave: sterilize for 15 min at 121°C. Unfortunately, this standard does not ensure sterility. The neophyte often misinterprets this standard as a sterilizing cycle of 15 min at 121°C instead of 15 min of thermal exposure of the center of the item to be autoclaved.2
The Role of Conventional Diagnostic Tools
Published in Johan A. Maertens, Kieren A. Marr, Diagnosis of Fungal Infections, 2007
Paul E. Verweij, Henrich A. L. van der Lee, Rijs Anthonius J. M. M.
Although most opportunistic fungi grow well on standard microbiological media, such as blood agar, chocolate agar, and brain heart infusion broth, medium that specifically supports the growth of fungi or inhibits the growth of other microorganisms is commonly used. Most commonly used are Sabouraud’s dextrose agar and potato dextrose agar, which should be included in the work-up when mycological culture is specifically requested or when microscopy is positive for yeasts or hyphae. The yield of this agar is superior to standard bacteriologie medium (30). Antibacterial agents are commonly added in order to suppress the growth of bacteria, especially when material is obtained froma semi-sterile site (BAL fluid) or non-sterile sites. Antibiotics commonly used include chloramphenicol, gentamicin, penicillin, streptomycin, or ciprofloxacin (31). Another compound that is frequently incorporated into fungal culture media is the eukaryotic protein synthesis inhibitor cycloheximide. The addition of this compound is aimed at inhibiting the growth of saprobic molds that are clinically not relevant. However, clinically significant molds can also be inhibited, including S. apiospermum, C. neoformans, most zygomycetes, and some species of Candida and Aspergillus (31). In specific cases, plates with and without cycloheximide can be inoculated and incubated. Nutrient agars supplemented with other compounds can be used for the culture of specific fungi, such as dermatophytes (actidione), Malassezia spp. (oxe-bile and tween 40, Dixon agar), or Cryptococcus spp. (Guizotia abyssinia seeds, birdseed agar). As sporulation of molds is required to enable morphologic identification, media are used with reduced availability of nutrients in order to facilitate this process. Conventional Sabouraud’s dextrose agar can be diluted (Takashio), or in some cases even water-based agar can be required to induce sporulation (32).
Novel thiazolinyl-picolinamide based palladium(II) complex-impregnated urinary catheters quench the virulence and disintegrate the biofilms of uropathogens
Published in Biofouling, 2020
Deeksha Rajkumar, Durairajan Rubini, M. Sudharsan, D. Suresh, Paramasivam Nithyanand
The ability of palladium(II) complexes (c and f) to eradicate preformed biofilms at their respective BIC (Table S1) was investigated using 24-well clear bottom polystyrene microtitre plates (NEST Biotechnology, Korea) containing urinary catheter pieces which were incubated in synthetic urine medium and normal microbiological media. 100 µl of mid log phase cultures were added to 1 ml of sterile LB broth and 1 ml of sterile synthetic urine medium with catheter pieces (1 cm x 1 cm) in each well, and the plates were incubated under static conditions for 24 h at 37 °C. After incubation, without disturbing the biofilm formed, 50 µl of palladium(II) complexes (c and f) at their Biofilm Inhibitory Concentration (BIC) were added and further incubated for 24 h at 37 °C. After incubation, the spent medium was removed and the biofilms formed on the 24 well plate and urinary catheters were stained with crystal violet and solubilised with ethanol. The OD was then measured at 595 nm using ELISA plate reader (Nithyanand et al. 2010) (Rubini et al. 2020).