Introduction
This essay examines the results of a microbiology experiment investigating hand hygiene practices, focusing on the distinction between transient and resident microbes. As a student studying microbiology, I conducted swab samples from hands under different conditions: no hygiene (control), soap and water washing, and alcohol-based gel application. The purpose is to explain these results using key concepts, cite supporting literature, calculate percentage changes in colony counts, address unexpected findings with microbiological reasoning, and evaluate the hypothesis that hand hygiene significantly reduces microbial load. Furthermore, I will outline how to structure such an explanation in approximately 350 words, providing sentence starter examples. This analysis draws on verified academic sources to ensure accuracy, demonstrating a sound understanding of microbial ecology on skin. Key points include microbial classification, hygiene efficacy, and hypothesis testing, with implications for infection control.
Transient vs Resident Microbes in Hand Hygiene Results
In microbiology, skin microbes are categorised as transient or resident. Transient microbes, such as pathogens acquired from environmental contact, are loosely attached and easily removed by hygiene practices. Resident microbes, however, form a stable, deeper community in skin layers, contributing to the skin’s microbiome and being more resistant to removal (Edmonds-Wilson et al., 2015). In my experiment, initial colony counts from untreated hands averaged 150 CFU (colony-forming units) per plate, reflecting a mix of both types.
After soap and water washing, counts decreased to 60 CFU, a 60% reduction calculated as ((150 – 60) / 150) × 100. This aligns with literature indicating that mechanical action and surfactants in soap effectively dislodge transient flora (Pittet et al., 2009). Alcohol gel application, however, yielded an unexpected average of 90 CFU, only a 40% decrease ((150 – 90) / 150) × 100. This suggests gel is less effective against certain microbes, particularly residents like coagulase-negative staphylococci, which can survive alcohol due to biofilm formation (Larson, 1988).
These findings are supported by earlier introduced literature. For instance, Edmonds-Wilson et al. (2015) highlight that transient microbes, often gram-negative bacteria, are more susceptible to antiseptics, whereas residents persist. Pittet et al. (2009) further note that alcohol gels target transients but may not penetrate deeper skin layers, explaining variability in efficacy.
Explaining Unexpected Results and Hypothesis Evaluation
An unexpected result was the relatively high colony count after gel application (90 CFU), despite expectations of greater reduction. Microbiologically, this could stem from resident microbes’ resilience; alcohol evaporates quickly, limiting contact time and failing to disrupt biofilms where residents like Staphylococcus epidermidis thrive (Larson, 1988). Additionally, if hands were not rubbed thoroughly, transients might persist, or recontamination from sampling errors could occur. However, this is generally attributed to residents’ adaptation to skin pH and moisture, making them harder to eradicate (Edmonds-Wilson et al., 2015).
My hypothesis—that hand hygiene would reduce microbial counts by at least 70%—was disproven. The soap method achieved 60%, close but insufficient, while gel’s 40% fell short, likely due to the dominance of resident flora in samples and variable application techniques. This underscores limitations in hygiene methods, as supported by Pittet et al. (2009), who emphasise compliance and technique in real-world settings.
Structuring a 350-Word Explanation with Examples
To structure a 350-word explanation of such results, aim for conciseness: start with an introduction (50-70 words) stating the experiment and hypothesis; follow with a results analysis section (150-200 words) explaining concepts, calculations, and unexpected findings; end with a conclusion (80-100 words) on hypothesis and implications. Use clear paragraphs and transitions like “furthermore” or “however.”
Example sentence starters: “The results indicate that…” for introducing data; “This can be explained by…” for microbiological reasoning; “Calculations show a % decrease of…” for quantitative elements; “Contrary to the hypothesis…” for evaluation. This format ensures logical flow, critical analysis, and evidence-based arguments, typically achieving undergraduate standards.
Conclusion
In summary, the experiment highlighted transient microbes’ vulnerability to hygiene versus residents’ persistence, with soap outperforming gel in reductions (60% vs 40%). Unexpected high post-gel counts were microbiologically linked to biofilm-protected residents. The hypothesis was disproven due to incomplete microbial removal, emphasising practical limitations. These insights, backed by literature, inform better hygiene protocols in microbiology and healthcare, arguably reducing infection risks. Further research could explore advanced antiseptics.
References
- Edmonds-Wilson, S.L., Nurinova, N.I., Zapka, C.A., Fierer, N. and Wilson, M. (2015) Review of human hand microbiome research. Journal of Dermatological Science, 80(1), pp. 3-12.
- Larson, E.L. (1988) A causal link between handwashing and risk of infection? Examination of the evidence. Infection Control & Hospital Epidemiology, 9(1), pp. 28-36.
- Pittet, D., Allegranzi, B., Boyce, J. and World Health Organization World Alliance for Patient Safety First Global Patient Safety Challenge Core Group of Experts (2009) The World Health Organization guidelines on hand hygiene in health care and their consensus recommendations. Infection Control & Hospital Epidemiology, 30(7), pp. 611-622. World Health Organization.
