Lower urinary tract infection

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Introduction0:00–0:23

With cystitis, cyst- refers to the bladder, and -itis refers to inflammation, therefore cystitis describes an inflamed bladder, which is usually the result of a bacterial infection, but also can result from fungal infections, chemical irritants, foreign bodies like kidney stones, as well as trauma.

Pathophysiology0:23–1:03

Now a urinary tract infection, or UTI, is any infection of the urinary tract, which includes the upper portion of the tract—the kidneys and ureters, and the lower portion of the tract—the bladder and urethra.
So cystitis, when it’s caused by an infection, is a type of lower UTI. Lower UTIs are almost always caused by an ascending infection, where bacteria typically moves from the rectal area to the urethra and then migrate up the urethra and into the bladder.
Having said that, on rare occasions, a descending infection can happen as well where bacteria starts in the blood or lymph and then goes to the kidney and makes its way down to the bladder and urethra.

Causes1:03–2:00

Normally, urine is sterile, meaning bacteria doesn’t live there; the composition of urine, which has a high urea concentration and low pH, helps keep bacteria from setting up camp.
Also, though, the unidirectional flow in the act of urinating also helps to keep bacteria from invading the urethra and bladder.
Some bacteria, though, are better surviving in and resisting these conditions, and can stick to and colonize the bladder mucosa.
E. coli accounts for the vast majority of UTIs, also though, other gram negative bacteria that can infect the bladder include Klebsiella, Proteus, Enterobacter, and Citrobacter species.
On the other hand, gram positive bacteria can also cause problems, like Enterococcus species, and Staphylococcus saprophyticus, which is actually the second most common cause after E.
coli and particularly affects young, sexually active women. That said, as far as risk factors go, sexual intercourse is a major risk factor, because bacteria can be introduced into the urethra, and this is sometimes even referred to as “honeymoon cystitis”.

Risk Factors2:00–3:25

In general, women are at higher risk for cystitis than men, due to having a shorter urethra. This is because bacteria that are ascending up the urethra don’t have to travel as far.
Also, in post-menopausal women there is a decrease in estrogen levels which causes the normal protective vaginal flora to be lost, increasing the risk of a UTI.
Other risk factors include presence of a Foley catheter in the urethra, which can introduce pathogens. Another risk factor is having diabetes mellitus, since people with diabetes tend to have hyperglycemia or high blood glucose.
Normally with an infection, neutrophils move out of the circulatory system toward the infection, called diapedesis, as well as carry out phagocytosis, but hyperglycemia inhibits these processes, making those neutrophils less effective at killing invaders.
Also, infant boys with foreskin around their penis have a slightly higher risk of a UTI compared to infant boys who’ve have had a circumcision.
A final important risk factor is impaired bladder emptying causing urinary stasis, which means urine tends to sit still, allowing bacteria the chance to adhere and colonize in the bladder.

Signs and symptoms3:25–4:21

Symptoms of cystitis include suprapubic pain, which is pain in the lower abdomen, dysuria, which is painful or difficulty urinating, as well as frequent urination and urgency, meaning you have to go a lot and you have to go now, and typically the urine voids are small in volume.
Having said that, symptoms can differ by age; infants might have a fever, become fussy, and feed poorly, whereas elderly patients might feel fatigue, become incontinent, or even develop delirium.
Symptoms that’re not typically present with lower UTIs are systemic signs like fevers and nausea or vomiting, as well as pain at the costovertebral angle which is the angle formed on either side of the back between the twelfth rib and the vertebral column, are all usually absent in a lower UTI, and if they do occur though, this might suggest an upper urinary tract infection, which includes an infection of the kidneys themselves.

Diagnosis4:21–5:57

If a urinalysis is done, there may be signs of inflammation like pyuria, the presence of white blood cells in the urine, which can make the urine appear cloudy.
Having a couple white blood cells in the urine can be normal, but it’d be considered abnormally high if there are more than 5 white blood cells per high powered field on microscopy or more than 10 white blood cells per mL on a hemocytometer.
Similarly, a dipstick test that shows the presence of leukocyte esterase, which is an enzyme created by leukocytes, or white blood cells.
It might also be positive for nitrites, since gram negative organisms like E coli. convert nitrates in the urine to nitrites, but it’s worth remembering that not all uropathogens are able to do that.
Alright and finally a urine culture is the gold standard for diagnosis, and it’s considered positive if it shows more than 100,000 colony-forming units per mL from a clean catch urine sample, although a lower number of colony-forming units per mL might still indicate an infection depending on the source of the specimen and the specifics of the clinical scenario.
And remember that this test assumes that the bacteria that grows is a known bacterial cause of UTIs and that the patient has clinical symptoms.
Now, if there is pyuria but the urine culture doesn’t reveal a bacteria, this is known as sterile pyuria, and it suggests urethritis, inflammation of just the urethra, as opposed to cystitis.
Isolated urethritis is most commonly caused by Neisseria gonorrhoeae and Chlamydia trachomatis, both of which are sexually transmitted infections.

Imaging studies5:57–6:53

For a UTI, imaging studies can also be helpful, for example, a renal ultrasound can be used for children who may have a kidney malformation which could contribute to developing a UTI.
In addition, a voiding cystourethrogram or VCUG might be used, which is where an individual is given a radiocontrast liquid and fluoroscopy which are like real-time Xrays, and then they watch how that fluid gets urinated out.
This is particularly helpful in children with severe or recurrent UTIs to detect evidence of vesicoureteral reflux, which is the retrograde movement of urine from the bladder back up into the ureters and kidneys.
The degree of vesicoureteral reflux can vary and it is an important risk factor for kidney scarring with a UTI. Finally, in some situations, renal scintigraphy using DMSA, which is a radionuclide, sometimes called a DMSA scan, can be used to detect evidence of kidney scarring.

Treatment and prevention6:53–7:28

Treatment for a lower UTI is usually antibiotics targeted to the bacterial cause and symptoms usually clear up within a few days as the urine becomes sterile, at the same time pain medication may also sometimes be given.
Preventing UTIs mainly involves drinking lots of fluids to help flush out bacteria that may try to ascend up the urethra and emptying the bladder as often as possible especially relevant for women after sexual activity, and finally maintaining good hygiene like wiping from the urethra to the rectum, all of which are aimed at preventing fecal bacteria from making it up the urethra.
Alright, as a quick recap—cystitis is inflammation of the bladder usually caused by bacterial infection, which makes it a type of lower urinary tract infection.

Review7:28–8:12

E coli’s by far the most common culprit, and risk factors include female gender, sexual intercourse, having catheters, diabetes mellitus, having penile foreskin in infant boys, and urinary stasis.