Lower urinary tract infection: Clinical sciences

Lower urinary tract infections, or lower UTIs, primarily include infections of the urinary bladder and urethra, called cystitis and urethritis respectively. Most UTIs are caused by bacteria that typically compose the normal gastrointestinal flora, especially gram-negative rods, such as E. coli, followed by Klebsiella pneumoniae and Proteus mirabilis. Depending on the setting and patient’s risk factors, lower UTIs can be classified as uncomplicated, complicated, CAUTI, and UTI in pregnancy.

Alright, if a patient presents with signs and symptoms suggestive of a lower UTI, you should first perform an ABCDE assessment to determine if they are unstable or stable. If unstable, first stabilize the airway, breathing, and circulation. This means you might have to intubate the patient, provide supplemental oxygen, obtain IV access, and monitor vital signs before doing further workup.

Now that you know how to manage unstable patients, let’s go back to the ABCDE assessment and discuss stable ones. If your patient is stable, you should first perform a focused history and physical examination, and order labs like a urinalysis and urine culture. History might reveal symptoms like dysuria, urinary frequency and urgency, and sometimes even blood in urine. On the other hand, physical exam could reveal suprapubic tenderness to palpation. As far as labs go, the urinalysis will be positive for nitrites and leukocyte esterase, and will reveal pyuria or WBCs and possibly hematuria or RBCs.

Now here’s a clinical pearl to keep in mind! It’s important to note whether hematuria is painful or painless. Painful hematuria suggests diagnoses like infection or nephrolithiasis. On the other hand, painless hematuria can be a sign of underlying conditions such as renal malignancies, polycystic kidney disease, or autoimmune rheumatologic conditions, such as IgA nephropathy. At this point, you should suspect a lower UTI.

Now, if your patient is a healthy, pre-menopausal biologically female individual with no systemic symptoms, like fever or chills, as well as no vaginal discharge, you should suspect an uncomplicated lower UTI. Next, start empiric antibiotic therapy with medications that cover most types of gastrointestinal flora, like nitrofurantoin; trimethoprim-sulfamethoxazole, or TMP-SMX; or fosfomycin. If urine culture reveals growth over 100,000 colony forming units per milliliter, it confirms the diagnosis, so consider tailoring antibiotics based on culture results.

Now, here’s another clinical pearl! Uncomplicated lower UTIs are especially common in biologically female individuals due to the proximity of the urethra to the rectum. The urethra is further away in biological males, so they are less likely to develop UTIs, and for that reason they’re always considered complicated lower UTIs regardless of the severity.

Moreover, a UTI in a biological male individual can resemble other conditions like prostatitis. You can differentiate this based on additional prostatitis symptoms, like pain in the pelvis, perineum or penis; a slow, dribbling urine stream; and systemic symptoms, like fever. If so, perform a digital rectal exam to check for prostatic hypertrophy, and order labs to look for an elevated prostate-specific antigen or PSA for short .Alright, now let’s move on and talk about complicated lower UTIs.

These include UTIs that occur in biological males, as well as in elderly, immunocompromised, and renal transplant patients, or in any patient who presents with systemic symptoms like fever and chills, or as a result of urinary obstruction, instrumentation, and urinary catheters. Keep in mind that complicated UTIs might be caused by resistant organisms, so you should initiate empiric antibiotic therapy with more broad-spectrum antibiotics, such as fluoroquinolones, TMP-SMX, or third-generation cephalosporins. Next, obtain blood cultures to rule out bacteremia. If urine cultures come back positive, with or without a positive blood culture, you can make the diagnosis of complicated lower UTI, so tailor antibiotics based on culture results.

Okay, if a patient is pregnant, and has urinary symptoms, it’s important to suspect UTI in pregnancy and not wait for urine culture results.