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Infectious Disease
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Susanna J. Dunachie, Hanif Esmail, Ruth Corrigan, Maria Dudareva
Different types of agar plates select different pathogens. Blood agar is the commonest agar media and supports the growth of most bacteria. MacConkey agar is selective for Gram-negative gut pathogens (Figure 3.9). Sabouraud agar selects fungi such as Aspergillus.
Bacteria Causing Gastrointestinal Infections
Published in K. Balamurugan, U. Prithika, Pocket Guide to Bacterial Infections, 2019
B. Vinoth, M. Krishna Raja, B. Agieshkumar
EIEC are very similar to Shigella and possess the same toxin and virulence factors as that of Shigella. Both EIEC and Shigella appear to have evolved from nonpathogenic E. coli by acquisition of invasion plasmid (pINV) at different times. The pathogenesis and clinical features are similar to Shigella infection (Refer Shigella); however, the incidence is less when compared to Shigella. Children younger than 5 years of age are more commonly affected. They are transmitted through contaminated food and water and person-to-person spread also occurs. They are diagnosed by the presence of nonlactose fermenting colonies on MacConkey agar and later by nucleic acid hybridization technique and phenotypic assay for identifying the specific virulence genes and their cytotoxicity pattern. Antibiotics are not routinely recommended for EIEC infections.
Microorganisms
Published in John C Watkinson, Raymond W Clarke, Louise Jayne Clark, Adam J Donne, R James A England, Hisham M Mehanna, Gerald William McGarry, Sean Carrie, Basic Sciences Endocrine Surgery Rhinology, 2018
Ursula Altmeyer, Penelope Redding, Nitish Khanna
Another useful reaction is the ability to metabolize lactose, and on the basis of this they can be split into lactose fermenters and non-fermenters. A number of commonly used media for the culture of Gram negative organisms, such as the MacConkey agar, contain a colour indicator and if the organism ferments lactose the resulting change in pH will lead to a colour change (Figure 19.6), allowing for a categorization of the organism on the first day that growth is observed.
Atypical enteropathogenic E. coli are associated with disease activity in ulcerative colitis
Published in Gut Microbes, 2022
Maximilian Baumgartner, Rebecca Zirnbauer, Sabine Schlager, Daniel Mertens, Nikolaus Gasche, Barbara Sladek, Craig Herbold, Olga Bochkareva, Vera Emelianenko, Harald Vogelsang, Michaela Lang, Anton Klotz, Birgit Moik, Athanasios Makristathis, David Berry, Stefanie Dabsch, Vineeta Khare, Christoph Gasche
Fifty-seven E. coli isolates were grown on MacConkey agar for 24 hours under aerobic or anaerobic conditions, using Anaerobox and AnaeroGen sachets (Thermo Scientific, Oxoid). Single colonies were inoculated in 5 ml brain heart infusion (BHI, 37 g/L) medium with supplements (5 g/L yeast extract, 1 g/L NaHCO3, 1 g/L L-cysteine, 1 mg/L vitamin K1, 5 mg/L hemin) or in LB medium and grown under aerobic or anaerobic conditions for 6 hours at 37°C. Bacterial cells were diluted to an OD600 = 0.05. 100 µl of cell suspension was transferred to the U-bottom polystyrene 96-well plates (Costar) in four technical replicates. Plates were incubated at 37°C for 48 hours under aerobic or anaerobic conditions. Supernatants were removed, bacterial biofilms were fixed with 150 μL BOUIN solution (0.9% picric acid, 9% formaldehyde and 5% acetic acid) for 15 min and washed three times with 190 μL PBS. For staining, 150 μL 0.1% crystal violet solution was added for 10 min and washed three times with H20. For biofilm quantification, crystal violet in dried plates was dissolved in 190 μL 30% acetic acid and the plate was placed on a shaker for 1 h. Absorbance of 1:5 dilutions was measured on an Anthos 2010 microplate reader at 595 nm and 405 nm reference wavelength. Pairwise comparison was performed with the Mann–Whitney U test and ANOVA with Dunn’s multiple comparison test for comparing multiple groups.
Detection of mobile colistin-resistance gene variants (mcr-1 and mcr-2) in urinary tract pathogens in Bangladesh: the last resort of infectious disease management colistin efficacy is under threat
Published in Expert Review of Clinical Pharmacology, 2021
Bayasrin Ara, Umme Laila Urmi, Tanjum Ara Haque, Shamsun Nahar, Adity Rumnaz, Tamanna Ali, Mohammed Shah Alam, Abu Syed Md. Mosaddek, nor Azlina a Rahman, Mainul Haque, Salequl Islam
Collected urine samples were inoculated on MacConkey agar (Liofilchem, Italy) and cysteine-, lactose-, and electrolyte-deficient (CLED) agar (Liofilchem, Italy) simultaneously. MacConkey agar supports gram-negative UTI pathogens (Supplementary Figure 1A), while CLED agar aids in the growth of gram-negative bacteria and gram-positive cocci if present in urine samples. Urine cultures were incubated at 37°C overnight in aerobic conditions. Colony counts of 102 or 103 CFU/mL were considered a cutoff value for a probable UTI infection [23]. Gram’s staining and biochemical tests initially identified Growth-positive bacteria. A rapid biochemical-test kit API 20E (BioMe´rieux, Durham, NC), consisting of carbohydrate batteries and enzymatic substrates in a set of chromogenic panels, was used to confirm the isolated identity (Supplementary Figure 1B) [24]. A part of the bacterial identity was validated by the polymerase chain reaction (PCR) amplification and sequencing of the 16S rDNA gene [25]. The isolates were preserved in 30% glycerol in Trypticase Soy Broth (TSB) at – 80°C until further antimicrobial susceptibility analysis.
Effects of Brazilian green propolis extract on planktonic cells and biofilms of multidrug-resistant strains of Klebsiella pneumoniae and Pseudomonas aeruginosa
Published in Biofouling, 2020
Pâmela Beatriz do Rosário Estevam dos Santos, Damara da Silva Ávila, Lucas de Paula Ramos, Amanda Romagnoli Yu, Carlos Eduardo da Rocha Santos, Andresa Aparecida Berretta, Samira Esteves Afonso Camargo, Jonatas Rafael de Oliveira, Luciane Dias de Oliveira
Eight multidrug-resistant strains of K. pneumoniae and P. aeruginosa were evaluated. The bacteria were donated by clinical laboratories from the Grupo Policlin Saúde (São José dos Campos, SP, Brazil) and Valeclin Laboratório de Análises Clínicas (São José dos Campos, SP, Brazil), with identification and antibiograms performed using the MicroScan autoSCAN-4 system (Beckman Coulter, Brea, CA, USA). Additionally, reference strains from the American Type Culture Collection (ATCC) of K. pneumoniae (ATCC 4352) and P. aeruginosa (ATCC 15442), stored at the Laboratory of Microbiology and Immunology (ICT-UNESP), were evaluated for comparative purposes. These strains were kept at −80 °C in Brain Heart Infusion broth (BHI; Himedia, Mumbai, India) with 20% glycerol. Bacterial activation was performed on MacConkey agar (Kasvi, São José dos Pinhais, PR, Brazil) with incubation at 37 °C for 24 h.