Which of the following is the commonest bacteria causing Catheter Associated Urinary Tract Infection (CAUTI)?

UPPSC 2023

Applied Microbiology & Infection control

Easy

Appeared in: UPPSC 2023

Explanation

Escherichia coli (E. coli) is the most frequent cause of Catheter-Associated Urinary Tract Infections (CAUTI), responsible for a significant majority of cases.
It is a gram-negative bacterium that is a normal inhabitant of the human gastrointestinal tract (gut flora).
Infection typically occurs when E. coli from the patient's own perineal or rectal area migrates along the external surface of the catheter and ascends into the bladder.
Once in the bladder, the bacteria can multiply and form a biofilm on the catheter surface, leading to a persistent infection.

Option A: Acinetobacter is a significant pathogen in healthcare settings, but it is more commonly associated with ventilator-associated pneumonia and bloodstream infections in critically ill patients, not as the primary cause of CAUTI.
Option C: While Pseudomonas aeruginosa is a common cause of hospital-acquired infections, including UTIs, it is less frequent than E. coli. It is often implicated in patients with long-term catheterization or those who have undergone multiple courses of antibiotics.
Option D: Klebsiella species are a well-known cause of CAUTI and are often associated with multi-drug resistance. However, in terms of overall frequency, they are second to E. coli.

Clinical Relevance

Nursing practice connection: Knowing Etiology of Catheter-Associated Urinary Tract Infections (CAUTI) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Knowing that E. coli from the patient's own gut flora is the most common cause reinforces the critical importance of meticulous perineal hygiene during daily care and maintaining a closed, sterile drainage system.
Nurses are at the forefront of CAUTI prevention. A key nursing action is to question the continued need for an indwelling catheter daily and advocate for its prompt removal, as the duration of catheterization is the single greatest risk factor for infection.
What if? If a patient with a suspected CAUTI has been on broad-spectrum antibiotics for a prolonged period, the nurse should anticipate that the infection might be caused by a more resistant organism like Pseudomonas or even a fungus like Candida, rather than the typical E. coli.

How to Approach the Question

This is a factual recall question asking for the 'commonest' cause of a specific type of infection.
Identify the key concepts in the question stem: 'Catheter Associated Urinary Tract Infection (CAUTI)' and 'commonest bacteria'.
Consider the anatomical location. The urinary meatus is in close proximity to the perineum and anus, making contamination from gut flora a high probability.
Evaluate the options provided. All are known hospital-acquired pathogens.
Recall or deduce that Escherichia coli is the most abundant facultative anaerobe in the human colon and the leading cause of UTIs in general. This makes it the most likely candidate for CAUTIs as well.
Select Escherichia coli as the most statistically frequent cause of CAUTI.

Concept Tested & Keywords

Concept Tested: Etiology of Catheter-Associated Urinary Tract Infections (CAUTI)
Stem keywords: Catheter Associated Urinary Tract Infection, CAUTI, commonest bacteria
Lead-in keywords: Which

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E6 Microbiology Applied AnjuDhir 3e Part 2 p. 131-133

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