According to MayoClinic.com, a urinary tract infection is caused when bacteria infect the urethra, bladder, ureters or kidneys. The urethra is typically affected first by bacteria that enter from the anal area or from the vaginal area. Urinary tract infections that are limited to the urethra and bladder can cause irritating symptoms such as abdominal pain, pain with urination, nausea and vomiting. Infections that extend to the ureters and kidneys, however, can be more serious and in some cases life-threatening.
Significance
As discussed by MayoClinic.com, bacteria enter the urinary tract through the urethra and then multiply in the bladder. Bacteria have an easier time traveling to the bladder in women because the urethra is much shorter than in men. Bacteria from the gastrointestinal tract are a frequent cause of urinary tract infection because the anus is located close to the urethral opening. Sexually transmitted diseases are also potential causes of urinary tract infection because of the proximity of the vagina to the urethra.
Bacteria in Routine Urinary Tract Infections
The bacteria Escherichia coli, or E.coli, is the most common cause of uncomplicated urinary tract infection. It typically lives in the intestines and is often spread to the urinary tract when women wipe themselves back to front after urinating. Staphylococcus saprophyticus causes 5 to 15 percent of UTIs and typically occurs in younger women, according to the University of Maryland Medical Center. Other causes include klebsiella, enterococci, proteus, ureaplasma and mycoplasma.
Bacteria in Severe Urinary Tract Infections
The bacteria that cause more severe urinary tract infections, such as those that invade the kidney, are caused by similar bacteria. As discussed by the University of Maryland Medical Center, it is thought that the same bacteria may be more virulent. This means that they are more capable of spreading and causing infection. Fungal infections can also occur in severe infections, typically with candida species. Pseudomonas and serratia are two types of bacteria that rarely occur with routine urinary tract infections but are more common in complicated ones.
Overcoming Bacteria in UTIs
Any change in the amount of acid in the genital and urinary tract can make a patient more or less susceptible to infection. Lactobacilli are a type of bacteria that increase the acidic environment in the urinary tract and make a patient less susceptible to infection. Antibiotics that kill off these bacteria may make a patient more susceptible to infection. Estrogen loss after menopause also reduces lactobacilli and may increase the risk of infection.
Treatment
Treatment of a urinary tract infection involves killing the bacteria causing the infection using a medication called an antibiotic. According to MayoClinic.com, there are many antibiotics that can be used to kill the bacteria. The specific antibiotic chosen depends on the bacteria and that bacteria's susceptibility to these medications. A urine culture can be checked that both identifies the bacteria and allows the physician to determine which antibiotics will work well to kill the bacteria. Common antibiotics used include amoxicillin, nitrofurantoin, ampicillin, ciprofloxacin, levafloxacin and bactrim.
