Catheter-associated urinary tract infection: Clinical sciences

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Catheter-associated urinary tract infection, or CAUTI for short, is a urinary tract infection in the presence of an indwelling urinary catheter or after the recent removal of the catheter, typically in the last 48 hours.
So to decrease the chances of patients developing CAUTIs, you should try to avoid urinary catheters if possible, or remove them as soon as they are no longer needed.
When they arise, CAUTIs are most commonly caused by Escherichia coli and Klebsiella pneumoniae, which can colonize the catheter and use it to gain access to the urinary tract.
Now, CAUTIs can be symptomatic or asymptomatic. Symptomatic UTI, or SUTI, is the more commonly diagnosed type because the patient will have symptoms.
On the other hand, asymptomatic UTIs are often discovered incidentally when blood and urine cultures are ordered during the workup for other conditions like sepsis.
Asymptomatic bacteriuria, or ASB, is when pathogens are found in the urine but not the blood. Asymptomatic bacteremic urinary tract infection, or ABUTI, is when the pathogen is found in both the urine and blood.Now, if you suspect CAUTI, first, you should obtain a focused history and physical examination, and order labs, such as CBC, CMP, and urinalysis.
Based on the findings, we can either suspect ABUTI or CAUTI. First, let’s take a look at a patient who might have an ASB or catheter-associated ABUTI.
The patient might have a history of a current or recently removed indwelling catheter, and although they have no history of UTI symptoms and no findings on physical exam, their labs reveal pyuria and bacteriuria, meaning that their urine cultures are positive.
These findings are often consistent with ASB. However, if blood and urine cultures were ordered as workup of another condition, such as fever or sepsis, and both come back positive for the same pathogen, meaning that they match, this is catheter-associated ABUTI.
In that case, you should start antibiotics, and if indicated, remove or replace any indwelling catheter. Now let’s take a look at how to assess the culture results.
If the urine and blood cultures come back negative, or grow different pathogens, consider an alternative diagnosis. On the flip side, if the urine and blood cultures are positive for the same pathogen, the diagnosis is catheter-associated ABUTI, so don’t forget to tailor antibiotics based on culture results.
Finally, if the urine culture is positive, but the blood culture is negative, the diagnosis is ASB. If this is the case, assess indications for antibiotic therapy, like pregnancy, scheduled urologic intervention, or renal transplantation within the past 3 months.
If the patient has any of these indications, start tailored antibiotic therapy based on culture results. However, if there are no indications, then no treatment is needed.
Alright, now let’s go back and take a look at individuals who might have catheter-associated SUTI. They present with a history of a current or recently removed urinary catheter and a history of UTI symptoms.
These usually include fever, suprapubic discomfort, dysuria, as well as urinary frequency and urgency. Common physical exam findings include suprapubic and costovertebral angle tenderness.
In severe cases, especially in older patients, you might detect altered mental status, like confusion or lethargy. Finally, when it comes to labs, they usually reveal elevated WBC count, pyuria, and bacteriuria.
At this point, you can suspect catheter-associated SUTI. But, to confirm the diagnosis, again, you need to obtain a urine sample for culture.
While waiting for results, don’t forget to start empiric antibiotics and remove or replace the indwelling catheter if indicated.
Now let’s take a look at how to assess the culture results. If urine cultures are negative, consider alternative diagnoses.
On the flip side, if urine cultures come back positive, you can diagnose CAUTI, so make sure to tailor antibiotics based on urine culture results.
Alternatively, if cultures come back positive for fungal growth, switch to antifungal treatment. Once you initiate the treatment, assess the patient’s clinical response to treatment.
Adequate response means that the treatment is working and the patient is improving, so continue tailored antibiotics to complete a 7-10 days course of treatment.
On the flip side, inadequate response means that the patient is not improving. In this case, order a CT scan of the abdomen and pelvis to assess for potential urologic complications.
If a CT scan reveals no complications, you should consider an alternative diagnosis. On the other hand, if a CT scan reveals calculi, obstruction, or abscess, you should consult the surgical team.
Alright, as a quick recap… Individuals with a urinary catheter can develop a catheter-associated urinary tract infection or CAUTI, which includes asymptomatic bacteriuria or ASB, asymptomatic bacteremic urinary tract infection or ABUTI, and symptomatic urinary tract infection or SUTI.
Individuals with a history of a current or recently removed urinary catheter, and no symptoms or signs of urinary tract infection should make you think of ASB or catheter-associated ABUTI.
This might be confirmed if blood and urine cultures were ordered as workup of another condition and come back positive for the same pathogen, so they match, and you should start antibiotics and remove or replace the indwelling catheter.
If the urine and blood cultures are negative or do not match, consider an alternative diagnosis. On the other hand, if the urine and blood cultures are positive for the same pathogen, the diagnosis is catheter-associated ABUTI, so make sure to tailor antibiotics based on culture results.
Finally, if the urine culture is positive, and the blood culture is negative, the diagnosis is asymptomatic bacteriuria.
In this case, assess for indications that require antibiotic therapy and tailor antibiotics per culture results. On the flip side, if a person presents with a history of a current or recently removed urinary catheter, and positive signs and symptoms of urinary tract infection, think of catheter-associated SUTI.
To confirm the diagnosis, obtain a urine sample for cultures, but don’t forget to start empiric antibiotics and remove or replace the indwelling catheter.Negative urine cultures usually exclude catheter-associated SUTI, so you should consider an alternative diagnosis.
Positive urine cultures confirm the diagnosis, so tailor the antibiotics based on culture results, or switch to antifungals if cultures come back positive for fungal growth.
Finally, assess the patient’s response to treatment. If the patient is clinically improving, complete a 7-10 day course of antibiotic therapy.
On the other hand, if the patient is not improving, order a CT scan of the abdomen and pelvis to assess for urologic complications, such as calculi, obstruction, and abscess.
If these complications are present,
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