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Mycobacterium tuberculosis Diagnosis with Conventional, Molecular Probe, and Nanobiosensing Techniques
Published in V. R. Remya, H. Akhina, Oluwatobi Samuel Oluwafemi, Nandakumar Kalarikkal, Sabu Thomas, Nanostructured Smart Materials, 2022
Deepak V. Sawant, Shivaji H. Pawar
Isolation of MTB from clinical sputum samples is a challenging and tedious process [13]. There are so many traditional methods for the diagnosis of MTB, like a diagnosis of biochemical markers for the identification of different myco-bacteria, including MTB identification [14]. Various types of the biochemical test also used for confirmation of MTB tests, which include niacin production, nitrate reduction, tween-80 hydrolysis, aryl-sulfatase, urea hydrolysis, tellurite reduction, TCH sensitivity, catalase (qualitative and quantitative), growth on MacConkey agar and L J media, sodium chloride tolerance, etc., for identification of MTB [15]. The traditional TB diagnosis methods are usually preliminarily identified by traits such as rate of growth, pigmentation, and colony morphology and biochemical profiles [16, 17]. The traditional methods are well established, standardized, and relatively inexpensive but are slow in providing clinically relevant information and are limited in scope to the species for which a large number of strains have been studied.
Indicator organisms and the coliform concept
Published in Cara Gleeson, Nick Gray, The Coliform Index and Waterborne Disease, 1996
The earliest methods of water bacteriology were aimed at direct isolation of specific pathogenic organisms. The cultivation of Cholera vibrio from water and faecal samples was largely successful at that time, although difficulties were encountered with the detection of typhoid-like organisms (Bonde, 1977). Bacteriologists attempting to overcome the difficulty of isolating such organisms found that human faeces contained large numbers of aerobic, Gram-negative organisms that resembled typhoid bacteria. These bacteria were subsequently found to be bile salt-tolerant, facultatively anaerobic organisms capable of growth and of fermenting lactose at 37°C. Among this group, later known as the coliforms, was Bacterium coli. This organism was isolated from human faeces in 1885 by Escherich (Dadswell, 1990a). The coliforms were quickly recognized as possible indicators of faecal pollution and procedures were developed to detect and estimate their numbers in raw waters. Further advances in bacteriological techniques and the development of more suitable media meant that even small numbers of conforms could be detected. The most widely adopted method of isolation was inoculation of MacConkey Broth and incubation at 37°C for 48 hours. Cultures producing acid and gas were subsequently subcultured onto MacConkey Agar to eliminate obligate anaerobes. By definition a coliform became any organism that was isolated by this method.
Biosensors: a Potential Tool for Detection of Microbial Contaminants for Food Safety
Published in Megh R Goyal, Sustainable Biological Systems for Agriculture, 2018
Anurag Jyoti, Rajesh Singh Tomar
Enterohemorrhagic E. coli (EHEC) is exploited in sorbitol MacConkey agar (SMAC). The International Organization for Standardization (ISO) protocol (ISO 16654) recommends that addition of Cefixime and potassium tellurite to SMAC (CT-SMAC) may increase the selectivity in samples. E. coli O157 generally produces colorless colonies when cultured on this media, thus distinguishing it from other EHEC serogroups. EHEC O157:H7 colonies are confirmed with biochemical tests and immunoassays having the O157 somatic antigen and H7 flagellar antigen (Figure 6.1).
Monitoring the effect of environmental conditions on safety of fresh produce sold in Qatar’s wholesale market
Published in International Journal of Environmental Health Research, 2022
I. Elnemr, M. Mushtaha, Sathyavathi Sundararaju, Mohammad Rubayet Hasan, Kin-Ming Tsui, I. Goktepe
About 5 ml of each homogenized mixture was added to the same volume of sterile Brain Heart Infusion broth and incubated at 37°C with continuous shaking at 150 rpm for about 3–6 hrs to enrich the microorganisms as described by El-Nemr et al. (2019a). Exactly 0.1 ml of each diluted sample was spread in duplicate on the following selective media: i) Plate-Count Agar (PCA) used for total aerobic bacterial (TAB) counts, ii) Baird-Parker Agar (BPA) supplemented with egg yolk for Staphylococcus spp., iii) Eosin Methylene Blue Agar (EMBA) for total coliforms, iv) Listeria Selective Agar (LSA) for Listeria spp., v) MacConkey Agar (MCA) to grow E. coli and other gram negative enteric bacilli, vi) Xylose Lactose Tergitol 4 agar (XLT4) for Salmonella spp., vii) Potato Dextrose Agar (PDA) for total fungi, and viii) Rose Bengal Chloramphenicol Agar (RBCA) for enumeration of yeasts and molds. All media used in this study were purchased from Oxoid Ltd. Hampshire, UK.
Shifts of acidogenic bacterial group and biogas production by adding two industrial residues in anaerobic co-digestion with cattle manure
Published in Journal of Environmental Science and Health, Part A, 2021
Guilherme Henrique da Silva, Nathan Oliveira Barros, Larice Aparecida Rezende Santana, Jailton da Costa Carneiro, Marcelo Henrique Otenio
The cultivation medium EMB is a differential culture medium that inhibits the growth of Gram-positive bacteria and indicates if the bacteria ferment lactose or not and is used as a medium for slightly selective differentiation for isolation and differentiation of gram-negative enteric bacilli. The colonies of Escherichia coli are easily identifiable by their metallic green coloring in the middle of EMB. MacConkey Agar is a culture medium intended to grow gram-negative bacteria and to indicate lactose fermentation. Bacterial colonies that ferment lactose make the medium light pink and bacteria that are not lactose fermenting make the medium light yellow. The colonies of Pseudomonas aeruginosa has a coloration ranging from colorless to green.[30]
Detection of pathogenic bioaerosols and occupational risk in a Philippine landfill site
Published in Archives of Environmental & Occupational Health, 2018
Hera Angela M. Pagalilauan, Cielo Emar M. Paraoan, Pierangeli G. Vital
MacConkey agar is selective for Gram-negative bacteria. It also differentiates lactose fermenters versus non–lactose fermenters through difference in color. Thus, the reaction with the medium is not unique to K. pneumoniae but could be observed in different bacteria with the same characteristics. In a characterization done in another study, a few strains of Gram-negative bacteria P. stutzeri were recorded to have been able to ferment lactose.31 However, in another study, the said organism was not able to show lactose-fermenting characteristics in MacConkey agar.32 Similarly, A. larrymoorei, also under Gram-negative classification, did not ferment lactose in a study in Florida.33 By contrast, all strains of A. baumannii tested in a certain study were shown to have the capacity to produce acid from lactose and are known to be Gram-negative.34Enterobacter sp. was said to have almost indistinguishable difference in the growth characteristic of K. pneumoniae on MacConkey agar, which means that it has the same properties in terms of lactose fermentation and cell wall composition.35 The inaccuracy could be accounted for by the presence of crystal violet, which was used as a selective agent. This stain may have caused confusion in the judgement of color, especially that observable color changes are subtle.