You are a health care professional involved in the treatment of an elderly patie

Question

You are a health care professional involved in the treatment of an elderly patient receiving out patient hemodialysis through a central vascular catheter. During preparation for hemodialysis treatment on a particularly hectic day, you skip a step in your facility’s hand hygiene protocol and are not careful while putting on your gloves. Just a few cells of the bacterium Pseudomonas aeruginosa are wiped from your hand onto the outside of your glove and are then deposited at the edge of the patient’s catheter. Just 5 of these cells are pushed further into the catheter, adhere to the plastic and start dividing. The patient finishes hemodialysis treatment and goes home. The generation time of this P. aeruginosa strain growing as a biofilm on the catheter, under these conditions is 5 hours.

1.) How many bacteria are present in the catheter after 48 hours?

After 48 hrs., the patient returns for another hemodialysis treatment. During this second treatment, the clump of P. aeruginosa cells in the catheter are flushed into the patient’s bloodstream. Some cells in the biofilm are dead, but a total of 25 cells remain alive, enter the patient’s bloodstream and begin dividing.

Eventually, the patient is rushed to the emergency room with symptoms of sepsis. At the time she
is admitted to the hospital, it is determined that she has 102 cells/mL of P. aeruginosa in her blood. If she has 3.9 L of blood in her body,

2) How many total bacterial cells are in her blood at the time she is rushed to the hospital? (0.75pts)

3) How many generations have the bacteria been through from the time the cells entered her blood until she arrived at the hospital?

4) How many days have passed since the bacteria entered her blood? (Assume a constant generation time of 5 hours in blood)

Explanation / Answer

1. Initial 5 cells enters the catheter.

Generation time =5 hours

Nt = N0 * 2n

where Nt = number of cells in population at time t

N0 = number of cells in population initially

N = number of generations

Here, n = 48/5 = 9.6

So, Nt = 5*29.6

So, after 48 hours approximately 3880 number of cells that will be present.

2. 3.9L = 3900ml

In 1ml 102 cells are present.

So, in 3900ml number of cells that would be present = 3900×102 = 397800

3. Nt = N0×2n

(log Nt - log N0)/ log 2 = (5.59 - 0.69)/0.3010 = 4.9/0.3010 = 16.28

So, 16.28 is the number of generations.

4. Approximately 16 generations have survived and to attain this 16×5 hours would have been required, which is 80 hours

So, number of days would be 80/24 = 3.3 days approximately.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.