The Treatment of Bladder and Kidney Infections
The GU system (genito-urinary) is involved with eliminating waste and clearing metabolized substances from the bloodstream. It is comprised of
- kidneys
- ureters (tubes that carry urine from the kidneys to the bladder)
- bladder, and
- urethra (tube that carries urine from the bladder to the outside world)
When infected, most commonly happening in the bladder (“cystitis”) and the kidney (“pyelonephritis”), in that order, antibiotics are necessary to limit suffering and damage. Damage to the kidneys, especially, can impact it function and even cause problems like hypertension and electrolyte imbalances; heart problems are therefore only one oversight away.
Cystitis Explained
The bladder is only one urethra away from the outside world. In men this isn’t much of a problem, but in women, where the urethra is much shorter, it is. Exposure to bacteria can allow contact and colonization, via the urethra, like is seen with frequent tub baths in women. Also, the mechanical act of intercourse can colonize a women’s vagina, residing under the bladder, or drive bacteria into a man’s urethra for advancement into his bladder.
Pyelonephritis Explained
The kidneys can become infected either from below (rising infection originating in the bladder) or from above (infecting it via the bloodstream with sepsis). Either way, an infection in the kidney is serious. The bladder, even though it complex in its function, pales in comparison when compared to the dynamic processes within one’s kidneys. Besides clearing the bloodstream of waste and metabolic byproducts, it also detoxifies harmful substances by this process. There is a physiologic dance between renin (an enzyme produced in the kidneys) with angiotensin II (made in the kidneys and lungs) where inverse ratios between them alternate based on hydration, blood pressure, and salt (sodium) retention. Renin and angiotensin II control these as part of the renin-angiotensin system. Damage to the kidneys from a destructive infection can therefore doom a patient to hypertension or electrolyte disturbances that can result in cardiac arrhythmias. The filtration process itself, a miracle of separation and extraction, can be compromised permanently. Additionally, pyelonephritis is painful, fraught with high fevers, and can scar the kidneys, creating chronic kidney disease, which is typically the first step toward a cascade of life-threatening conditions.
Prevention
The GU system is designed such that no special precautions need be taken to prevent infection. Emphasis on special. There are some general ways to avoid infection, however. Avoiding frequent tub baths are helpful in women, where the shorter uethra makes transport of bacteria easier. For both men and women, emptying the bladder after intercourse will swish out any bacteria driven into the urethra by this mechanical process. Also, any risky behavior that would put one at risk for sepsis, such as intravenous drug abuse, would be a poor life-choice.
Treatment of cystitis
Since antibiotics are the standard for treating GU infections, strong consideration must be given to the rationale for antibiotic selection. Certainly, a culture and sensitivity (C&S) should point out an antibiotic to which the identified bacteria are sensitive. Treating blind (“empiric treatment”) with antibiotics is advisable to get a 2-day jump on treatment, pending the results of the C&S. But choosing antibiotics empirically shoud be more than just eenie-meenie-miney-mo. Some historically are known to be ineffective or to suffer from bacterial resistance to them, such as ampicillin and amoxicillin. Avoiding these and ones to which a patient is allergic are obvious strategies.
Antibiotics for cystitis include the following first-choice drugs:
- Nitrofurantoin (Macrodantin, Macrobid)
- Double-strength trimethoprim-sulfamethoxazole (Bactrim DS, Septra DS)
- Fosfomycin
- If allergies or resistance results from a C&S exclude the above, consider:
- Amoxicillin-clavulanate
- Cefpodoxime
- Cefdinir
- Cefadroxil
- Fluoroquinolones: ciprofloxacin (Ciproflox); levofloxacin (Levaqui); ofloxacin; these offer shorter (3-day or less) courses that the other antibiotics, if issues such as compliance makes a longer course inadvisable.
- Cephalexin (Cephalex)
These are all oral medications. If there is any question of which type of GU infection it is—cystitis vs pyelonephritis—nitrofurantoin and fosfomycin are not recommended since they do not get into the kidney tissue enough to eradicate infection there (pyelonephritis).
Treatment of pyelonephritis
A kidney infection may be treated on an outpatient basis only with fluoroquinolones, but the severity of the condition usually requires intravenous or intramuscular antibiotics. Since fluroquinolones are taken orally, it makes a good choice for empiric treatment pending the C&S.
Inpatient, IV fluoroquinolone, an aminoglycoside, a third-generation cephalosporin, or an extended-spectrum penicillin can be selected based on C&S and physician preference.
After treatment
After treatment, another C&S is mandatory as a “test of cure” (TOC). The TOC is to determine that the infection is really gone. Recurrent infections may be due to incomplete treatment (which the TOC will identify), a coincidental subsequent infection (bad luck), or a predisposing factor for recurrence, such as a foreign body or a retained stone. Sometimes a chronic prophylaxis with daily macrodantin is indicated with predisposing factors.
Genito-urinary infections, including cystitis and pyelonephritis, except with the rare case of a fungal infection, are caused by bacteria. Pyelonephritis, more serious and even life-threatening, is a true emergency. Therefore, a full course of antibiotics are mandatory, followed by a test-of-cure culture-and-sensitivity. Anything less puts a person at extreme risk for falling dominos—bad ones.
Resources:
- https://www.uptodate.com/contents/acute-complicated-cystitis-and-pyelonephritis?source=search_result&search=kidney%20infection&selectedTitle=1~83.
- https://www.uptodate.com/contents/diagnosis-and-acute-management-of-suspected-nephrolithiasis-in-adults?source=search_result&search=kidney%20stones&selectedTitle=1~150.
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