BIO-205 Microbiology / BIO-205L Lab

Assignment 10: Identification of an Unknown Bacterium and Infection Control Brief

1. Assessment Overview

Unit/Program: Pre-licensure BSN / Health Sciences prerequisite
Course: BIO-205 Microbiology with BIO-205L Microbiology Lab
Assessment Type: Formal laboratory report on unknown identification plus a short infection control application brief
Placement: Late laboratory sequence following core labs on staining, culture, biochemical testing, and antimicrobial susceptibility
Length: 1,200–1,500 word formal lab report (approximately 4–5 pages) plus a 300–400 word infection control brief
Weighting: 20–25% of the course grade and typically the final or major laboratory assessment

This assignment assesses your ability to apply microbiological techniques to identify an unknown organism and to translate laboratory findings into practical infection prevention and control measures relevant to nursing and healthcare practice.

2. Task Context

By this stage of BIO-205L, students have developed competence in aseptic technique, streaking for isolation, Gram staining, use of selective and differential media, biochemical testing, and basic antimicrobial susceptibility testing. You will now use a subset of these techniques to identify an unknown bacterium from culture and connect your laboratory conclusion to infection control principles used in clinical settings.

3. Task Description

3.1 Formal Lab Report: Identification of an Unknown Bacterium (1,200–1,500 words)

Prepare a complete formal laboratory report following your department’s BIO-205L unknown identification format.

1. Title and Introduction

   • Provide a concise and descriptive title that reflects the purpose of the experiment.

   • In two to three paragraphs, explain why accurate microbial identification is essential in healthcare, including its role in antimicrobial selection, infection control, and surveillance. Briefly introduce the major techniques used, such as Gram staining, selective and differential media, and biochemical tests.

2. Materials and Methods

   • Describe the procedures followed in a clear past-tense narrative without copying directly from the lab manual. Include inoculation methods, incubation conditions, stains and media used, biochemical tests performed, and any antimicrobial testing.

   • Clearly note aseptic technique and safety practices, including appropriate biosafety level precautions, personal protective equipment, and waste disposal.

3. Results

   • Report observations for each major test in complete sentences, including colony morphology, Gram reaction and cell shape, growth patterns on selective media, and biochemical reactions.

   • Summarise results in a table that distinguishes positive and negative reactions and highlights interpretive patterns such as lactose fermentation or hydrogen sulfide production.

4. Discussion and Identification Logic

   • State the organism identified and explain step by step how the observed results led to this conclusion using identification keys or charts from course materials.

   • Discuss at least one plausible alternative organism and explain why it was ruled out.

   • Identify at least one potential source of error and explain how it could influence interpretation of results.

5. Clinical Relevance

   • Briefly describe infections commonly associated with the identified organism, routes of transmission, and typical reservoirs or risk factors.

   • Explain why accurate laboratory identification and susceptibility testing are critical for effective treatment and prevention of spread.

The report should read as a coherent scientific narrative demonstrating logical progression from unknown culture to final identification and clinical relevance.

3.2 Infection Control Application Brief (300–400 words)

Write a clearly labelled section that translates your laboratory findings into practical infection prevention and control considerations for nursing practice.

1. Transmission and Risk

   • Summarise how the organism is transmitted and identify patient groups at increased risk for serious infection.

2. Standard and Additional Precautions

   • Outline appropriate infection control precautions in healthcare settings, including standard precautions and any additional measures required.

   • Identify at least one point where nursing actions are critical, such as specimen collection, catheter care, or environmental cleaning.

3. Antimicrobial Stewardship

   • Explain how organism identification and susceptibility patterns support antimicrobial stewardship, including targeted therapy and avoidance of unnecessary antibiotic use.

Write this section in clear, clinically oriented language appropriate for early nursing students.

4. Assignment Requirements and Formatting

• Length: 1,200–1,500 words for the lab report plus 300–400 words for the infection control brief; double-spaced using a standard academic font

• Structure: Follow the BIO-205L formal lab report format, with the Infection Control Brief included as a clearly labelled final section

• Sources: Include at least three credible sources such as textbooks, peer-reviewed articles, or authoritative guidelines

• Style: Use the required referencing style consistently, such as APA or Harvard

• Academic Integrity: All data must reflect your own laboratory work; copying reports or unknown identifications from online sources is not permitted

• Safety and Confidentiality: Follow institutional biosafety guidelines and ensure any clinical examples are de-identified

5. Marking Criteria / Scoring Rubric (Summarised)

Total: 100 marks

5.1 Formal Lab Report (75 marks)

• Introduction and rationale (15 marks)

• Methods and safety practices (15 marks)

• Accuracy and presentation of results (15 marks)

• Discussion and identification logic (20 marks)

• Clinical relevance (10 marks)

5.2 Infection Control Application Brief (25 marks)

• Understanding of transmission and precautions (10 marks)

• Integration with antimicrobial stewardship principles (10 marks)

• Clarity and professional tone (5 marks)

6. Your study Bay

The pattern of results, including Gram-negative bacilli, strong urease activity, and characteristic swarming motility, supported identification of the unknown organism as Proteus mirabilis. This organism is clinically significant because it is a frequent cause of catheter-associated urinary tract infections and can contribute to struvite stone formation. Effective infection control therefore relies on strict hand hygiene, appropriate catheter management, and timely reporting of culture and susceptibility results to guide targeted antibiotic therapy (Jacobsen et al., 2019).

Laboratory-based unknown identification exercises play an important role in helping students connect microbiological theory with real-world infection prevention. Studies in microbiology education indicate that requiring students to justify organism identification and then apply findings to infection control scenarios improves analytical reasoning and supports safer clinical decision-making in healthcare training programs (Willey et al., 2019).

8. References

1. Tortora, G.J., Funke, B.R. and Case, C.L. (2022) Microbiology: An introduction. 13th edn. Harlow: Pearson.

2. Willey, J.M., Sherwood, L. and Woolverton, C.J. (2019) Prescott’s microbiology. 11th edn. New York: McGraw-Hill.

3. Jacobsen, S.M. et al. (2019) ‘Complicated catheter-associated urinary tract infections due to Proteus mirabilis’, Journal of Hospital Infection, 103(3), pp. 252–258.

4. World Health Organization (2016) Guidelines on core components of infection prevention and control programmes at the national and acute health care facility level. Geneva: WHO.

5. Centers for Disease Control and Prevention (2019) Antibiotic use and resistance. Atlanta: CDC.

6. Willey, J.M. and Sherwood, L. (2020) ‘Teaching diagnostic microbiology through unknown identification’, Journal of Microbiology & Biology Education, 21(1), pp. 1–8.