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Most bacteria can grow to some extent in the presence of ______
oxygen
The E-test uses rectangular plastic strips with the predefined, continuous and exponential gradient of ______ concentration.
antibiotic
Bacteria ______ is a biological activity wherein microorganisms multiply themselves in a predetermined culture media under laboratory conditions.
culture
Species that are naturally found in low ______ environments, such as in deep wounds or abscesses or the deep ocean, will typically grow best in the absence of oxygen.
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The ______ test provides a direct quantification of antimicrobial susceptibility of microorganisms.
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Cultivate means to ______ and help grow bacteria.
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Minimum Inhibitory Concentration (MIC) is considered as the lowest concentration of an antimicrobial that inhibits the visible growth of a ______.
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For example, Staph.epidermidis is a species that grows best on the ______ surface.
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Streptococcus ______ can be found as normal flora in the nasopharynx of healthy individuals.
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Some bacteria, such as ______ and Bacteroides, cannot grow in the presence of oxygen at all.
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Aerotolerant organisms, like ______ and Lactobacillus, do not require oxygen for growth but can tolerate its presence.
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______ bacteria require oxygen for survival and are present in aerated moist soil containing organic carbon sources.
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Obligate ______ are aerobic bacteria that compulsorily require oxygen for deriving energy, growth, reproduction, and cellular respiration.
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The microorganism ______ can be found as normal flora in the nasopharynx of healthy individuals.
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______ are aerobic bacteria that can grow in either aerobic or anaerobic conditions, switching from aerobic respiration to fermentation or anaerobic respiration if oxygen is absent.
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Some bacteria, such as ______ and Mycobacterium tuberculosis, cannot grow in the absence of oxygen.
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Facultative bacteria behave both aerobically and ______, according to the prevailing conditions.
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In reduced environments, they acquire energy via ______ pathways.
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The microaerophilic bacteria require ______ but in very low concentrations.
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There are mainly three methods of cultivation of anaerobic bacteria such as an atmosphere free of ______.
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An anaerobic jar is a container into which inoculated plates or tubes are placed inside the chamber, and anaerobic conditions are created by adding water to a gas generator envelope that is placed in the jar just before ______.
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A candle jar is a container into which a lit candle is introduced before sealing the container's ______ lid.
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The candle's flame burns until extinguished by ______ deprivation, which creates a carbon dioxide-rich, oxygen-poor atmosphere in the jar.
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Openings in the side of an anaerobic box that is holding nine Petri plates supporting cultures are sealed by ______-like sleeves that allow for the handling of cultures inside the box.
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Inoculated plates or tubes are placed inside the ______, and anaerobic conditions are created by adding water to a gas generator envelope.
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Study Notes
Antimicrobial Susceptibility Testing
- Epsilometer test (E-test) is a quantitative method that provides direct quantification of antimicrobial susceptibility of microorganisms.
- It combines disk diffusion pattern with the determination of Minimum Inhibitory Concentration (MIC).
- MIC is the lowest concentration of an antimicrobial that inhibits the visible growth of a microorganism.
- E-test uses rectangular plastic strips with a predefined, continuous, and exponential gradient of antibiotic concentration.
Bacteria Culture and Cultivation
- Cultivation of bacteria is a biological activity where microorganisms multiply themselves in a predetermined culture media under laboratory conditions.
- Most bacteria can grow to some extent in the presence of oxygen, known as aerobic culture.
- Species that are naturally found in low oxygen environments, such as in deep wounds or abscesses, will typically grow best in the absence of oxygen – anaerobic culture.
- Examples of bacteria that can grow in aerobic culture include Staph. epidermidis, Staph. aureus, Streptococcus pneumoniae, Haemophilus influenza, and Moraxella catarrhalis.
Oxygen Requirements for Bacterial Growth
- Microorganisms can be found as normal flora in the nasopharynx of healthy individuals.
- Some bacteria cannot grow in the presence of oxygen at all, e.g. Fusobacterium and Bacteroides.
- Some bacteria cannot grow in the absence of oxygen, e.g. Pseudomonas and Mycobacterium tuberculosis.
- Some bacteria can grow in either aerobic or anaerobic conditions, switching from aerobic respiration to fermentation or anaerobic respiration if oxygen is absent, e.g. E. coli, Salmonella, Listeria, and Staphylococci.
Aerotolerant Organisms
- Aerotolerant organisms are those that do not require oxygen for growth but can tolerate its presence.
- An aerotolerant organism is classified as an anaerobe.
- Examples of aerotolerant organisms include Strept. pyogenes (harmful) and Lactobacillus (beneficial).
Cultivation of Aerobic and Anaerobic Bacteria
- Aerobic bacteria require oxygen for survival and are present in aerated moist soil containing organic carbon sources.
- There are two main types of aerobic bacteria: obligate aerobes and facultative and microaerophile aerobes.
- Obligate aerobes compulsorily require oxygen for energy, growth, and cellular respiration.
- Facultative bacteria can behave both aerobically and anaerobically, depending on the prevailing conditions.
- Microaerophilic bacteria require oxygen but in very low concentrations.
- Anaerobic bacteria can be cultivated using an atmosphere free of oxygen, an anaerobic indicator, and an anaerobic jar with a catalyst.
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Description
This quiz covers the principle of Epsilometer test (E test) and its application in determining antimicrobial susceptibility of microorganisms.
