A kidney infection, known medically as pyelonephritis, is a serious type of urinary tract infection (UTI) that affects one or both kidneys. It results from a bacterial invasion, typically a progression of an untreated bladder infection. A kidney infection is generally not contagious, meaning it cannot be passed directly from one person to another like a cold or the flu.
Is a Kidney Infection Transmissible?
Pyelonephritis is not classified as a contagious illness because it originates from bacteria already residing within the infected individual’s body. The infection is considered endogenous, meaning it arises from a person’s own microflora rather than being transmitted through external contact or shared surfaces. The specific bacteria responsible, most often Escherichia coli (E. coli), typically come from the digestive tract. The infection is established only after the bacteria move from the anal area into the urethra and then ascend through the urinary system, a unique internal migration.
The Internal Progression of Kidney Infections
The typical pathway for a kidney infection begins with the entry of bacteria into the urethra. Once inside, these microorganisms multiply, often causing a lower urinary tract infection, or cystitis, in the bladder. The infection becomes pyelonephritis when the bacteria successfully travel further up the urinary tract, ascending through the ureters—the tubes connecting the bladder to the kidneys.
This upward movement causes the bacteria to infect the tissue of the renal pelvis and kidney parenchyma. The natural, one-way flow of urine from the kidneys down to the bladder usually prevents this type of upward bacterial migration. Factors that obstruct this flow or compromise the urinary tract’s anatomy can facilitate the progression to a kidney infection. Blockages, such as kidney stones or an enlarged prostate in men, can cause urine to back up, creating a breeding ground for bacteria and increasing the likelihood of an ascending infection.
Recognizing Symptoms and Seeking Urgent Care
Symptoms of a kidney infection are generally more severe and systemic than those of a simple bladder infection, indicating the infection has spread beyond the lower urinary tract. The hallmark signs often include a high fever and shaking chills, which signal a significant systemic inflammatory response. Localized pain is also a distinguishing feature, presenting as a deep, aching sensation in the flank, which is the side and back area just below the ribs. Other symptoms often include nausea and vomiting, which can lead to dehydration.
Diagnosis typically involves a physical examination, urinalysis to check for white blood cells and bacteria, and a urine culture to identify the specific pathogen. Untreated pyelonephritis can lead to severe health consequences, making immediate medical attention a necessity. If the infection spreads into the bloodstream, it can cause sepsis, a life-threatening complication.
Strategies for Preventing Urinary Tract Infections
Since a kidney infection is almost always a complication of a lower UTI, prevention focuses on stopping the initial bacterial entry and multiplication in the bladder. Maintaining adequate hydration is a powerful strategy, as drinking plenty of fluids helps to flush bacteria from the urinary tract. Good hygiene practices are also important for reducing the risk of bacterial entry into the urethra.
- Aim to empty the bladder regularly, rather than holding urine for long periods.
- Wipe from front to back after using the toilet to prevent bacteria from the anal region from contaminating the urinary opening.
- Urinate shortly after sexual activity to flush out any bacteria introduced into the urethra.
- Address underlying conditions, such as structural issues in the urinary tract or recurrent kidney stones.