Micrococcus luteus is a gram positive bacterium commonly found in the human nasal cavity. It utilises organic compounds present in nasal secretions as a nutrient source and does not affect host health or immune function under normal physiological conditions.

How would you classify this symbiotic relationship?

Researchers are investigating the impact of diet on gut health. They collect stool samples from participants and use high-throughput DNA sequencing to analyse the genetic material of the microbial communities present in the samples. This approach is best suited to studying:

Q5. R. pickettii infections in humans are uncommon because the skin provides a strong physical barrier to infection and is an inhospitable environment for some microorganisms. Describe two properties of the skin that may prevent R. pickettii colonisation. (1-2 sentences) (2 marks)

The hospital discovered that the patient’s R. pickettii infection was caused by a contaminated saline solution that was used to rinse and irrigate surgical wounds. In response, the Therapeutic Goods Administration (TGA) instituted a national recall of the contaminated saline solution.

44 cases of R. pickettii infection were detected nationwide and linked to the contaminated saline. While most infections were asymptomatic, six immunocompromised individuals developed symptoms of infectious disease and required specialist care.

Following the surgical procedure the patient developed a fever and their condition rapidly deteriorated. A blood sample was collected from the patient and sent to the clinical microbiology laboratory for testing. The bacterium Ralstonia pickettii was identified in the sample and confirmed as the causative agent of the patient's infection. 

R. pickettii

is commonly found in freshwater aquatic

ecosystems and thrives in the presence of algal species such as

Q2. How would you classify the relationship between R. pickettii and C. sorokiniana? (select all that apply)

Q1. Examine the nasopharyngeal culture in Figure 1.1. What conclusion can you reach?

Which statement is correct regarding screening of hospital patients for MRSA?

In hospital environments, S. aureus can be transmitted from one person to another via both direct or indirect routes.

If a clinician wanted to know if a MRSA strain was present in a clinical sample, which gene(s) would they target in a PCR?