Clinical Bacteriology Module 1

Questions and Answers

What is the main function of β-galactosidase in metabolism?

Oxidizes galactose

Transports glucose

Hydrolyzes glucose

Hydrolyzes lactose (correct)

Which of the following is a final electron acceptor in anaerobic respiration for methane reducers?

Carbon dioxide (correct)

Nitrate

Oxygen

Sulfate

Which pathway is NOT mentioned as a metabolic pathway for glucose following hydrolysis?

Entner-Duodoroff pathway

Fermentation

Embden-Meyerhof pathway

TCA cycle (correct)

What distinguishes Late/Delayed Lactose Fermenters (dLFs) from Non-Lactose Fermenters (NLFs)?

dLFs have both β-galactoside permease and β-galactosidase Signup and view all the answers

Why is anaerobic respiration considered less energy efficient than aerobic respiration?

It generates less energy compared to aerobic respiration Signup and view all the answers

What is the term used for a two-part name for each species?

Binomial Signup and view all the answers

Which classification scheme groups organisms into five kingdoms?

Five Kingdom Signup and view all the answers

Microbiology is primarily concerned with the study of which type of organisms?

Microorganisms Signup and view all the answers

What is the abbreviated term used for subspecies based on phenotypic differences?

subsp. Signup and view all the answers

Which of the following is NOT a component of microbial taxonomy?

Ecological impact Signup and view all the answers

Which kingdom includes organisms classified as prokaryotes?

Monera Signup and view all the answers

What are biovarieties based on?

Biochemical test results Signup and view all the answers

What is the main purpose of an antimicrobial susceptibility test?

To test pathogens for resistance to drugs Signup and view all the answers

What is the primary basis for Whittaker's Classification of microorganisms?

Nutritional pattern Signup and view all the answers

What naming convention is used to identify organisms in the binomial system?

Genus and species name Signup and view all the answers

In which kingdom do organisms primarily engage in photosynthesis?

Plantae Signup and view all the answers

Which of the following is true regarding the family name in nomenclature?

Capitalized and ends with –aceae Signup and view all the answers

What is an example of the type of organisms included under the Monera kingdom?

Bacteria and Cyanobacteria Signup and view all the answers

Which classification scheme replaced the polynomial system during the Middle Ages?

Binomial system by Linnaeus Signup and view all the answers

What is the correct format for writing scientific names in print?

Both genus and species italicized Signup and view all the answers

Which of the following describes Protista organisms?

Unicellular, plant-like, animal-like, and fungal-like Signup and view all the answers

What is the pH level that indicates a positive reaction in the Methyl Red Test?

4.5 Signup and view all the answers

In the context of anaerobic respiration, what molecule is typically not the final electron acceptor?

O2 Signup and view all the answers

What compound is produced when tryptophan is hydrolyzed?

Indole Signup and view all the answers

What type of metabolism does the mixed acid fermentation pathway involve?

Fermentative metabolism Signup and view all the answers

What color indicates a negative result in the Methyl Red Test?

Yellow Signup and view all the answers

What is the main precursor used by some bacteria in tryptone broth for carbon and nitrogen?

Tryptophan Signup and view all the answers

Which of the following best describes the end products of the mixed acid fermentation pathway?

Stable acid and low pH Signup and view all the answers

In the Voges-Proskauer test, what compound is produced from glucose?

Acetyl methyl carbinol Signup and view all the answers

What indicates a positive result when using Simmons citrate medium?

Change in color from green to blue Signup and view all the answers

Which test determines the presence of the cytochrome oxidase system?

Oxidase Test Signup and view all the answers

What is a common consequence of using a light inoculum in citrate medium assays?

False-negative reaction Signup and view all the answers

What is indicated by a lavender color within 10 to 15 seconds in the Kovac Oxidase Test?

Positive result Signup and view all the answers

Which of the following organisms are considered oxidase positive?

Neisseria Signup and view all the answers

What is the function of the indicator phenol red in Christensen citrate medium?

To signal a change in pH Signup and view all the answers

Which group of organisms is usually classified as oxidase negative?

Micrococci and Staphylococci Signup and view all the answers

What effect does fermentation have on enzyme activity in citrate media?

It inhibits oxidase activity Signup and view all the answers

Study Notes

Bacterial Cell and Classification

Bacteria are classified using a binomial nomenclature system, where each species has a two-part name.
Microorganisms consist of bacteria, viruses, archaeans, certain algae, protozoa, and some fungi.
Microbiology involves the study of small living organisms, known as microorganisms, which are ubiquitous in nature.

Medical Microbiology

Involves the cultivation and identification of pathogens from patient specimens.
Focuses on microbial physiology, growth requirements, morphology, and biochemical characteristics.
Antimicrobial susceptibility testing is performed for effective disease treatment.

Microbial Taxonomy

Classification: Organizes microorganisms into specific groups based on shared traits.
Nomenclature: Follows a universal naming system, using a genus and species format.
Identification: Involves determining key features of microorganisms for comparison with others.

Classification Schemes

Five Kingdom System: Monera, Protista, Fungi, Plantae, Animalia.
Six-Kingdom System (Whittaker’s Classification): Including Archaebacteria and Bacteria.
Classification has historical roots dating back over 2,000 years, evolving from polynomial to binomial systems.

Biochemical Tests

Tests involve the oxidation of substrates, with electron transport systems and pH indicators.
Differentiate between fermentative and oxidative metabolism, affecting energy efficiency.
Late/Delayed Lactose Fermenters (dLFs) possess certain enzyme characteristics influencing their classification.

Methyl Red (MR) Test

Tests the stability of acid production from glucose fermentation.
Positive result: Red color indicating pH < 4.5; negative result: yellow color indicating pH > 6.2.

Indole Production Test

Uses tryptone broth where some bacteria hydrolyze tryptophan, producing indole.
A red color indicates a positive reaction when tested with Ehrlich and Kovack’s reagent.

Voges-Proskauer Test

Evaluates the production of acetyl methyl carbinol from glucose fermentation.
Negative result: No color change indicates no acetyl methyl carbinol production.

Citrate Utilization Test

Simmons citrate medium tests the ability of bacteria to utilize citrate as the sole nitrogen source.
Positive result: Color change from green to blue, indicating alkaline conditions.

Catalase Test

Tests for the presence of catalase enzyme, decomposing hydrogen peroxide into water and oxygen.
Positive result: Rapid evolution of oxygen bubbles indicates the presence of catalase.

Oxidase Test

Determines if bacteria possess the cytochrome oxidase system for aerobic respiration.
Positive result: Color change indicates the presence of oxidase; Neisseria and Pseudomonas are examples of oxidase-positive bacteria.

Additional Notes on Testing

Various media and indicators are used to determine the metabolic capabilities of bacteria, emphasizing the importance of selecting appropriate conditions for accurate results.
Modified methods (e.g., Kovac Oxidase Test) enhance specificity in differentiating bacterial species based on metabolic reactions.

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Description

This quiz covers the fundamental concepts of clinical bacteriology, including the parts of bacterial cells and classification techniques. It also explores the significance of polynomial and binomial nomenclature in microbiology. Test your knowledge of these essential topics in this first-semester module for AY 2024-2025.