Definition
Infection of the urinary tract (UTI) is one of the most common bacterial infection. (Swartz, 2010). According to Ronald (2002) UTIs account for up to 8 millions ambulatory care visits and 1.5 million discharges are diagnosed a year in the United States. Urinary tract infections may be classified as lower UTI (cystitis or urethritis) or upper UTI (pyelonephritis). Bacteriuria refers to the presence of bacteria in urine (Brashers, 2006) and acute cystitis is an illness caused by inflammation of the bladder epithelium or urethra as a result of such bacterial infection. Acute pyelonephritis is a clinical syndrome which derives out of inflammatory response to bacterial invasion of the renal parenchyma. Under this condition the patient may experience flank pain, fever and chills due to the inflammatory response to bacteria. (Brashers, 2006).
The term chronic cystitis and chronic UTI are used to describe patients with recurring infections, which could be categorised as relapse or reinfection. (Peterson, et al, 2006). Relapse could happen within 2 weeks of stopping therapy as recurrence of bacteriuria with the original infecting organism. Reinfection, on the other hand, is the recurrence of bacteriuria within a new organism caused by the entry of bacteria into the bladder from fecal-perennial area.
Contamination by bowel flora may occur if a virulent organism is involved. In the case of children it may happen if the child is immunosuppressed. (Anatoliotaki, et al., 2007). Chronic pyelonephritis refers to chronic bacterial infection, possible from the renal calculi or structural anomaly that may become a source of infection. (Ronald, 2002). We have to mention here that systemic extension of pyelonephritis can lead to a very serious condition known as urosepsis that can progress to septic shock and even cause death (Brashers, 2006).
Epidemiology
The prevalence of bacteriuria varies in different types of people. Normally the urinary tract is sterile. Cystitis and urethritis are found to be nearly 10 times more common in women than in men and affect approximately 20% of all women at least once in their lifetime with many having repeated infections resulting in substantial morbidity and necessitating constant medical attention. (Ronald, 2002).
Most cases involve sexually active young women. The association of UTI with sexual intercourse in women is reflected in the term honeymoon cystitis. (Ronald, 2002). Some studies show that women who use a diaphragm have a greater risk of UTI than women who use other methods of contraception. (Harrington & Hooton, 2000). Also, women with diabetes are at a higher risk of contracting UTIs. (Brashers, 2006).
In men and children, UTIs are found at a lower rate and mostly these relate to anatomic or physiologic abnormalities. Uncomplicated infections may happen in uncircumcised men or in sexually active homosexual men. (Harrington & Hooton, 2000). Also, the incidence of UTIs increases significantly in elder people. According to one study, the incidence rises up to 20% after the age of 70. (Godfrey & Evans, 2000). A significant increase in UTIs is seen in institutionalized elderly individuals. Also, UTIs could be epidemiologically classified as catheter-associated (nosocomial) and non-catheter-associated (community-acquired). (Godfrey & Evans, 2000).
Patient presentation
Patients with acute cystitis usually display symptoms like dysuria, urgency, and frequency, sometimes accompanied by suprapubic discomfort or gross hematuria. Fever rarely exceeds 38C if the infection is located only in the lower tract. Systemic signs are usually absent. Urine is cloudy, malodorous, and sometimes there will be the presence of blood. (Swartz, 2010).
The classic clinical presentation of acute pyelonephritis in adults consists of fever >38.5C, chills, and flank pain, which may radiate to the epigastric or lower abdominal quadrant areas. Radiation of the pain to the groin, malaise, anorexia, nausea, vomiting, diarrhea and headache, etc suggests ureteral obstruction. (Kasper et al., 2005). The illness may progress rapidly. The physical finding is variable, ranging from normal to the clinical features of septic shock.
The presentation of acute pyelonephritis can be confused with many other conditions, including bacterial pneumonia, myocardial infarction, acute hepatitis, cholecystitis, acute pelvic disease, and even varicella-zoster. (Kasper et al., 2005). Patients with diabetes may not have flank pain, and loss of blood sugar control may be the sole symptom of acute pyelonephritis. However, classic features of pyelonephritis do occur in elderly people. (Kasper, et al., 2005).
Women with urethritis usually present with dysuria, frequency, and pyuria but insignificant or no growth on bacterial urine cultures may have urethritis due to sexually transmitted pathogens such as chlamydia trachomatis, neiisseria gonorrhoeae, or herpes simplex virus. (Moore et al., 2002).
Catheter-associated UTIs generate minimal symptoms and no fever and such infections often disappear after catheter removal. Treatment without catheter removal usually fails. (Godfrey&Evans, 2000). Genitourinary sepsis leads to metastatic infection at other sites, such as endocarditis, meningitis, or vertebral osteomyelitis. (Kasper et al., 2005).
Diagnosis
In order to diagnose UTI, the culture of the urine is required for testing purposes. Such testing is mandatory for all suspected upper or lower tract infections. (Swartz, 2010). The simplest method is to obtain a clean-voided midstream urine specimen. The urine should be planted on culture media within 1 hour or refrigerated until it can be cultured to avoid a high colony count. A bacterial count of more than 100, 0000/ml (pyuria) confirms the diagnosis. (Kasper et al., 2005).
The lower count doesn’t necessarily rule out infection, especially if the patient is voiding frequently, because bacteria require 30-45 minutes to reproduce in urine. A diagnosis of asymptomatic bacteriuria in women requires two voided specimens with more than 100,000/ml, and in men, a single specimen growing more than 10000/ml of a single organism is specific for bacteriuria. (Kasper, et al.,2005).
The best diagnostic criterion for symptomatic infection with gram-negative aerobes in women requires a minimum of 100/ml with pyuria. (Kasper et al., 2005). Pyuria is the presence of more than five white blood cells per high-power field in centrifuged urine sediment or more than 10 cells per milliliter of unspun urine. (Kasper, et al.,2005). The leukocyte dipstick, a widely available office test, is less sensitive but is an acceptable simple alternative to the microscopic diagnosis of pyuria. Microscopic hematuria is present in 50% of patients with acute cystitis. Besides, blood culture is 25% positive in patients with acute pyelonephritis. (Peterson, et al, 2007).
While making a diagnosis, it is important to differentiate between upper from lower UTI, as the response to treatment and the ultimate prognosis depends on the infection site. Unfortunately, clinical criteria are not very reliable in localizing the site of infection. (Kasper et al, 2005). The Stamey test (ureteral cauterization) and Faieley test (bladder washout) are sensitive procedures to localize the site of infection. Both require instrumentation and are impractical for routine clinical practice. The use of noninvasive tests such as measurement of maximal urinary concentration ability, C-reactive protein, urinary proteins, or gallium scan in individual patients is limited.
Bacteria invading the tissue stimulate the production of an antibody that binds to the organism. Detection of antibody-coated bacteria has been used to localize infection to the upper tract. However, the prevalence of large numbers of false-positive and false-negative results, in such cases has the limited clinical ability. (Peterson et al., 2007). According to the Singapore Ministry of Health – National Government Agency (2005) there are certain tests that should be done for women with recurrent UTI. Kidney’s x-ray, ultrasound, intravenous urography and pyelogram, cystoscopy and CT may help to rule out structural abnormalities, obstruction or calculi. If the patient history and physical examination warrant so, a blood test and stained smear of the discharge may be carried out to rule out STD, such as gonorrhea, Chlamydia, and syphilis. (American College of Radiology, 2005).
Treatment
The optimal treatment is antimicrobial therapy with supportive measures such as hydration and urinary analgesia. The urine level of antimicrobial agents is a better indicator of therapeutic response than serum levels. (Pohl, 2007). In acute invasive renal infections, the agent selected should also provide adequate blood and tissue levels. The initial choice of treatment depends on local resistance patterns of uropathogenic. Optimal treatment regimens and duration for most UTIs remain controversial of 3 to 14 days regimens. (Singapore Ministry of Health-National Government Agency, 2005).
For example, in women, several single doses of 3-days treatment regimens have proven to cure 90% of infections limited to the lower tract. Singapore Ministry of Health-National Government Agency (2005) maintains that therapy with trimethoprim-sulfamethoxazole (TMP-SMX) is a better option because of the increased incidence of amoxicillin resistance among patients with community-acquired E coli infections.
Advantages of this choice include lower cost, ensuring compliance, besides the possibility of fewer and less severe side effects. There is minimal effect on the fecal flora so that repeated short courses can be used without the appearance of a resistant organism. (Kasper, et al.,2005). According to Anatoliotaki et al, (2007) antimicrobial resistance of E coli was found more commonly to ampicillin -56.4%, compared to 27.3% to trimethoprim-sulfamethoxazole (TMP-SMX).
All patients with symptoms of upper tract involvement should be treated with a 14 days course of an appropriate antimicrobial agent. Singapore Ministry of Health-National Government Agency, (2005) further claims that alternatives to the TMP-SMX could be Nitrofurantoin, Trimethoprim, Fluoroquinolones, Cephalosporins, and Beta- lactam-lactamase-inhibitor combinations. Patients with acute pyelonephritis should initially be managed in the hospital to facilitate close monitoring and initiation of treatment with parenteral antibiotics. (Pohl, 2007).
Initially, treatment should start with IV aminoglycoside, in combination with a cephalosporin, because hospital-acquired E coli tends to have a low level of sensitivity to ceftriaxone and ciprofloxacin. The administration of antibiotics should be reviewed and modified where necessary when urine culture results become available. Oral antibiotic therapy can be started following clinical improvement, with a treatment course of 14 days. (Pohl, 2007). Most patients become febrile with minimal flank tenderness after 48 hours of treatment. However, if their response is slow, investigations are needed to find out whether obstruction or other complications have entailed. Elderly and bed-confined patients should not be treated because of the futility of maintaining sterile urine and due to the emergence of resistant organisms with treatment. (Godfrey & Evans, 2000).
Recurrent infections happen in 50% of the patients within 1 year after treatment. Relapse results from failure to eradicate the organism. Continuous long-term suppressive therapy should be considered in the case of patients who have relapsed after prolonged courses. Half the usual daily dose of TMP-SMX, amoxicillin, cephalexin or fluoroquinolone is usually found to be an effective supportive regimen. (Singapore Ministry of Health-National Government Agency, 2005).
Most recurrent infections are reinfection from new organisms entering the bladder from the fecal-perineal area. Although resistant organism replaces the fecal flora of patients treated with sulfonamides, selection of high counts or resistant fecal flora is less common with TMP, nitrofurantoin, and quinolones.
Thus, reinfection with the resistant organism is rare. (Kasper et al., 2005). 6-month prophylaxis can be begun after existing infections are eradicated. UTI during pregnancy may have forms of asymptomatic bacteriuria, acute cystitis, or pyelonephritis. According to the Singapore Ministry of Health-National Government Agency, (2005), the choice of antibiotic for the asymptomatic bacteriuria in pregnancy would be based on culture and sensitivity and should be given to reduce the risk of pyelonephritis. In the case of acute cystitis in pregnant women, the recommendations are empirical therapy with cephalosporins, nitrofurantoin or trimethoprim-sulfamethoxazole is recommended. (Singapore Ministry of Health-National Government Agency, 2005).
In the instances of pyelonephritis during pregnancy, the recommendations are empirical therapy with a third-generation cephalosporin. The treatment could be modified based on culture results and appropriate antibiotics as deemed necessary should be administered for 14 days. (Singapore Ministry of Health-National Government Agency, 2005).