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    Epidemiology and Pathophysiology

    Lucy Yuan

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    Join date : 2009-06-23

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    Post  Lucy Yuan on Tue 23 Jun 2009, 12:29 pm

    Urinary Tract Infection in Boys Less Than Five Years of Age: A General Pediatric Perspective

    Hany M Nadi, Yasser A F Shalan, Hanan YA Al-Qatan , Saad Alotaibi
    Department of Pediatrics, Farwania Hospital, Kuwait

    Kuwait Medical Journal 2006, 38 (3): 220-225

    Research appraisal
    This research to examine the pattern of urinary tract infection (UTI) in boys < 5 years admitted to general pediatric wards and identifies the approach to imaging investigations. During the period from January 2002 through December 2002, 34 boys < 5 years of age were admitted to Farwania Hospital with UTI. Age at diagnosis, presenting features, urinal pathogens, acute phase reactants and imaging procedures were reviewed for these patients. All 34 patients in this study were less than one year. Fever was the most common presenting feature and was seen in 70.6% of patients. Pyuria was found in 77% , positive leukocyte esterase (LE) test in 85.7% and positive nitrite test in 45.7% of patients. Significant leukocytosis was found in 39.3%, high C-reactive protein (CRP) in 46.8% and high erythrocyte sedimentation rate (ESR) in 50% of children. Escherichia coli (E.coli) were the most common pathogen affecting 77.1% patients. Radiological investigations were recommended as follows: ultrasound scan (US) for all patients (94.2% did

    Unexplained fever in young boys should suggest UTI. Absence of fever does not exclude UTI, if other suggestive features exist particularly in the very young. UTI is commonly suggested by findings on urinalysis, on the other hand, negative urinalysis should not exclude the infection. Empiric antibiotics should cover gram-negative bacilli. Innovative strategies to ensure compliance to radiological investigations are needed.
    The epidemiology of UTIs in children varies with age. This age-dependent variation is of considerable clinical significance, since it defines important risk factors for UTI. The incidence of febrile UTIs is highest during infancy. In the age range from birth to 2 months, the diagnosis of acute pyelonephritis is usually made during evaluation for neonatal sepsis. The incidence of UTIs is about 4% in both male and female infants during the first year. However, most of the infections in male infants occur during the first 3 months. Numerous studies have shown that uncircumcised male infants have about 10 times as many UTIs as circumcised male infants, the infections occurring mainly during the first 3 months of life.
    Winberg and colleagues suggested that the increased risk of infection is a consequence of colonization of the infant's GI tract and genitals in hospital maternity units by strains of E coli of nonmaternal origin, those to which the infant has no passive immunity. The increased risk of a UTI in the uncircumcised male infant appears to be secondary to adherence of E coli to the unkeratinized squamous mucosal surface of the prepuce. The circumcised prepuce is much less likely to harbor these potential uropathogens.
    After the first year of life, the incidence of UTIs in boys drops to about 0.08%, while that in girls ranges from about 3% to 4% until 6 years. The higher incidence of UTIs in girls has been attributed to the relatively short female urethra. The incidence of first-time UTIs appears to be relatively low in children from 7 to 11 years, although good epidemiologic data to substantiate this are lacking. The annual incidence of UTIs has been given as 3 per 1000 girls and 0.2 per 1000 boys. The decreased incidence in this age group has been attributed to lengthening of the urethra in girls and the fact that most anatomic abnormalities predisposing to UTIs in boys would have been identified in earlier years.
    There is an increase in the incidence of UTIs in adolescent girls, which is correlated with the frequency of vaginal intercourse. The theory underlying the hypothesis that sexual intercourse promotes UTIs is that vigorous and frequent sexual activity traumatizes the female urethra and forces bacteria into the bladder. Only a fraction of women appear to be at risk for intercourse-associated infection, presumably those already prone to UTIs. The risk is further increased with condom use. There is a 2- to 8-fold increase in risk of a first UTI with use of a lubricated condom or an unlubricated condom in combination with a spermicidal gel or cream.
    Almost all UTIs are ascending in origin. Disturbance of the normal periurethral flora, which is part of the host defense against colonization by pathogenic bacteria, predisposes a person to a UTI. Bacteria of the periurethral flora also inhabit the distal urethra. Urine in the proximal urethra, urinary bladder, and other proximal sites in the urinary tract is normally sterile. Uropathogens must gain access to the urinary bladder and proliferate for infection to occur. Uropathogens in the distal urethra may gain access to the bladder because of turbulent urine flow during normal voiding or because of dysfunctional voiding. Successful urinary bladder colonization is unlikely unless bladder defense mechanisms are impaired because normal voiding usually results in an essentially complete washout of contaminating bacteria.
    After birth, the periurethral area, including the distal urethra, becomes colonized with aerobic and anaerobic microorganisms that appear to function as a defense barrier against colonization by uropathogens. In early childhood, enterobacteria and enterococci are part of the normal periurethral flora. Escherichia coli is the dominant gram-negative species in young girls, whereas E coli and Proteus species predominate in boys. Children as old as about 5 years are predisposed to have UTIs, partly because of periurethral colonization by E coli, enterococci, and Proteus species. These potential uropathogens usually diminish in the first year of life and are rarely found in children older than 5 years. Studies of girls and women prone to UTI showed that periurethral colonization occurs with the specific bacterium that causes the next infection.

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    Post  gillegarda/joanalynbalino on Tue 23 Jun 2009, 6:03 pm

    By : D2- Joanalyn S. Balino/ Gil Legarda

    Detection of Intracellular Bacterial Communities in Human Urinary Tract Infection

    David A Rosen,1 Thomas M Hooton,2 Walter E Stamm,3 Peter A Humphrey,4 and Scott J Hultgren1*

    Rosen, Hooton, Stamm, Humphrey, and Hultgren made this study in order to provide evidences that episodes of E. coli cystitis in humans may involve intracellular bacterial communities (IBC) pathogenic pathway similar to that observed in mice. E. coli strains that cause UTIs can invade the cells that serve as lining in the bladder. Then they replicate and form so-called intracellular bacterial communities (IBCs). Many of the infected cells fall off the bladder's surface into the urine, but IBCs also release bacteria, many of which have a long, slender filamentous appearance.They collected midstream, clean-catch urine specimens for culture and analysis from 80 young women between the ages of 18 and 49 y with acute cystitis prior to treatment and 20 different asymptomatic women seen for follow-up at least 1 wk after successful cystitis treatment for the comparative group . The exclusion criteria for both groups were; (1)antibiotic use in the prior week; and phenazopyridine use in the prior 2 d,(2) they manifested signs and symptoms of pyelonephritis, pregnancy, chronic illness like diabetes, recent catheterization, or known anatomic or functional abnormalities of the urinary tract. A questionnaire data was used that includes information about their general health, current UTI episode, and UTI and sexual histories. For the culture and analysis of the urine they used light microscopy, electron microscopy, and a technique called immunofluorescence.

    From 80 women with UTI, 65 (81%) E. coli, 4 (5%) Staphylococcus saprophyticus, 3(4%) Enterococcus,2 (3%) each of Enterobacter aerogenes, Klebsiella pneumoniae, and Proteus mirabilis, and one (1%) Citrobacter diversus. There was also one (1%) with high levels of both E. coli and S. saprophyticus. No one in the 20 comparative asymptomatic women had significant bacteriuria. 14 (100%) of the urines with IBCs had filamentous bacteria. compare with 19 of 66 (29%) urines without IBCs (p < 0.001). IBCs and filaments were observed only in urines with gram-negative uropathogens, with none of the gram-positive urines showing such evidence (p = 0.038). Every specimen that contained IBCs and the majority of specimens positive for filamentous bacteria (30 of 33, 88%) were from UTIs caused by E. coli. Filamentous bacteria were also observed in urine samples from women with cystitis caused by other pathogens. IBCs and filaments were associated with higher bacterial burdens (p = 0.014) and a longer duration of symptoms (p = 0.007)

    This research study suggests that intracellular bacterial communities may occur in woman having cystitis. This can be proved by the existence of exfoliated intracellular bacterial communities and filamentous bacteria in the midstream, clean-catch urine specimens in women having acute cystitis. With this study medicala practitioners can be guided with the treatment of urinary tract infection and the reoccurrence of this disease.

    Rosen, D., Hooton, T., Stamm,W., Humphrey,P., and Hultgren, S.(2007). Detection of Intracellular Bacterial Communities in Human Urinary Tract Infection. PLoS Med. December; 4(12): e329. Retrieved June 23, 2009 from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2140087&tool=pmcentrez

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    Post  alkhaloidz on Tue 23 Jun 2009, 11:02 pm

    Dyad 4
    Balajadia, Bond
    Zao, Alexis

    We want to add this study for additional data on Epidemiology of UTI

    Incidence rates and management of urinary tract infections among children in Dutch general practice: results from a nation-wide registration study

    We aimed to investigate incidence rates of urinary tract infections in Dutch general practice and their association with gender, season and urbanisation level, and to analyse prescription and referral in case of urinary tract infections. During one calendar year, 195 general practitioners in 104 practices in the Netherlands registered all their patient contacts. This study was performed by the Netherlands Institute for Health Services Research (NIVEL) in 2001. Of 82,053 children aged 0 to 18 years, the following variables were collected: number of episodes per patient, number of contacts per episode, month of the year in which the diagnosis of urinary tract infection was made, age, gender, urbanisation level, drug prescription and referral.

    The overall incidence rate was 19 episodes per 1000 person years. The incidence rate in girls was 8 times as high as in boys. The incidence rate in smaller cities and rural areas was 2 times as high as in the three largest cities. Throughout the year, incidence rates varied with a decrease in summertime for children at the age of 0 to 12 years. Of the prescriptions, 66% were in accordance with current guidelines, but only 18% of the children who had an indication were actually referred.

    We therefore conclude that based on what we've red in this study, that incidence rates of UTI does not solely depends on the gender, age or season but also the type or kind of area we live in (rural or urban areas). With this kind of researh result, the Nursing Profession will benefit from this by emphazing this facts during the Community immersion of the student nurses, by having a community wide teaching of UTI and its causes.

    Reference: Wing-Yee Kwok et. al. Incidence rates and management of urinary tract infections among children in Dutch general practice: results from a nation-wide registration study. PMC. April 2006

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    Post  guomanman on Wed 24 Jun 2009, 12:12 pm

    Urinary Tract Infections in
    Infants and Children in
    Developing Countries in the
    Context of IMCI

    Urinary tract infections (UTI) are one of the most common bacterial infections seen in children. It has been estimated that UTI are diagnosed in 1% of boys and 3-8% of girls. In the first year of life UTI is more prevalent in boys with rates of 2.7% compared with 0.7% in girls (Riccabona 2003). Most infections in boys occur in the first three months of life (Roberts and Akintemi 1999; Schalger 2001) but by school age, the rate has decreased in boys and increased in girls (Riccabona 2003). Studies have shown a 10-12 fold increased risk of UTI in uncircumcised boys (Roberts and Akintemi 1999; Wiswell 2000). The reported rate of recurrent UTI is around 12- 30% with risk greater in infants < 6 months, severe vesico-ureteric reflux and abnormal nuclear renal scans at time
    of first infection (Panaretto, Craig et al. 1999). UTI has accounted for febrile presentations in 7.5% of 442 infants <8 weeks, 5.3% of 945 infants <1 year, 4.1% of 501 children <2 years and 1.7% of 664 children <5 years (Schalger 2001). The Pediatric Research in Office Settings (PROS) Network of the American Academy of Pediatrics study showed UTI in 9% of 3066 febrile infants, < 3 months and 10% of these had bacteraemia (Newman, Bernzweig et al. 2002). Meningitis has been reported
    in 3-5% of infants in the first month of life with bacteraemic UTI (Wiswell 2000). Gram negative organisms are those most commonly isolated from urine samples of children with uncomplicated UTI with Escherichia coli (E. coli) accounting for 70 to 90% of infections (Schalger 2001; Riccabona 2003). Surveys have demonstrated bacteriuria in asymptomatic children of all ages from premature infants to school age children. It is now accepted that asymptomatic bacteriuria does not present a risk to a child of any age and screening for bacteriuria in the asymptomatic child is not indicated (Roberts and Akintemi 1999; Liao and Churchill 2001).


    1. American Academy of Pediatrics Committee on Quality Improvement, S. o. U. T. I. (1999). Practice
    parameter: the diagnosis, treatment, and evaluation of initial urinary tract infection in febrile infants and
    young children. Pediatrics 103(4).

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    Post  rodel_perez_rn on Thu 25 Jun 2009, 2:51 pm

    Evaluation of the Sysmex UF-100 Urine Cell Analyzer as a Screening Test to Reduce the Need for Urine Cultures for Community-Acquired Urinary Tract Infection
    Shine Young Kim, MD;1 Young Jin Kim, MD;1 Sun Min Lee, MD;1 Sang Hyun Hwang, MD;1 Hyung Hoi Kim, MD;1 Han Chul Son, MD;1 Eun Yup Lee, MD1,2
    Published: 01/29/2008

    The incidence of urinary tract infection (UTI) is a frequent complaint most especially among women. The method of detection still considers urinary culture as the golden standard as to confirm the diagnosis. However, the results of urine culture may vary depending on the method of collection and the microscopic analysis performed in the laboratory resulting to difficulty in reproducing consistent results. Recently, Japan introduces UF-100 flow cytometer, a device that can discriminate cells and crystals in urine as well as reporting the quantities of each. The purpose of this study was to evaluate the performance of UF-100 in detecting community-acquired UTI. 330 urine samples from random individuals were subjected to UF-100 analysis and quantitative culture. The culture plates were incubated for 24 hours then immediately after inoculation, urine specimens were analyzed for bacterial and WBC counts using UF-100. The cut-off values for WBC and bacterial count were calculated to have reference for the urine culture. The cutoff value determined by UF-100 as well as comparison with different cutoff values were determined to screen community-acquired UTI.

    With the 330 urine specimen which was subjected for culture, 66 went positive, 259 were negative and 5 are considered contaminated. Cutoff values for bacterial count indicates 38.5%-75.5% of unnecessary cultures may be eliminated using UF-100 analysis. Hence, WBC counts were not a good source of data to screen community-acquired UTI when compared to bacterial count. The utilization of UF-100 to determine bacterial count is much sensitive in contrast with other laboratory test, thereby reducing unnecessary urine culture and sensitivity tests.

    Through predicting urine culture results utilizing UF-100, clinician will be able to get more information to confirm diagnosis of community-acquired UTI and would aid them in preventing unnecessary prescription of antibiotics. The workload and costs for laboratory analysis will also be minimized allowing the clients to save resources. Since UF-analysis can be completed within an hour, the waiting time for the clients treatment to be administered will be shortened preventing further renal damage and complications.

    Authors and Disclosures
    Shine Young Kim, MD,1 Young Jin Kim, MD,1 Sun Min Lee, MD,1 Sang Hyun Hwang, MD,1 Hyung Hoi Kim, MD,1 Han Chul Son, MD,1 and Eun Yup Lee, MD1,2 from the 1Department of Laboratory Medicine, School of Medicine, and 2Medical Research
    Institute, Pusan National University, Pusan, Republic of Korea.
    byron webb romero
    byron webb romero

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    Post  byron webb romero on Thu 25 Jun 2009, 11:54 pm

    Dyad Three (3)
    Byron Webb A. Romero
    Von Deneb H. Vitto
    Raymond C. Ursal


    The ascending route is the most common way in which UTIs are initiated. Bacteria enter the urinary tract through the urethra and ascend to the bladder, and possibly the collecting system. This occurs more frequently in women because of a shorter distance from the urethra to the bladder and the close proximity to the vagina and perirectal area, both of which contain a high concentration of potentially pathogenic bacteria. UTIs are less common in men because of the increased distance of the urethral meatus from the bladder. Men do occasionally develop infections of the urinary tract, but they are more commonly seen in those with prostatic hypertrophy, renal stones, bladder catheterization, recent cystoscopy, and immunocompromise. Because of these associations, all UTIs in men should be considered complicated. The main host defense against bacterial infection is the flow of sterile urine through the urethra. This decreases the bacterial load, thus decreasing the likelihood of a bacterial infection occurring (Boie, Goyal & Sadosty, 2005).

    The uropathogens responsible for UTI have changed little through the decades. E. coli is still responsible for 75% to 95% of uncomplicated cases. S. saprophyticus is isolated in 5% to 15% of UTIs, and enterococci, Klebsiella, and Proteus mirabilis make up the remaining 5% to 10% (Gupta, Hooton & Stamm, 2001). Enterococcus tends to be a urinary tract pathogen in older men with abnormalities of the prostate gland. In general, the uropathogens leading to uncomplicated cystitis are much the same as those causing acute uncomplicated pyelonephritis. These pathogens are relatively adept at ascending, colonizing, and causing infection in the urinary tract.

    The common risk factors for the development of cystitis and pyelonephritis have been well studied. In women, recent sexual intercourse, use of a spermicide or diaphragm, and history of previous UTI all place the patient at increased risk. The classic teachings involving increased water intake, direction of wiping, cranberry juice, and voiding promptly after intercourse have not been supported in the data according to Krieger (2002). Risk factors for the development of UTI in healthy men include insertive anal intercourse, lack of circumcision, and a sexual partner with the same uropathogen. Such conditions as recent instrumentation of the genital tract, presence of a renal stone, and prostatic hypertrophy also increase the risk for UTI in men (Boie, Goyal & Sadosty, 2005).

    Diagnostic Evaluation
    In a study done by Bent and colleagues in 2002, the likelihood ratios of various signs and symptoms of UTI were evaluated. Using these data, the combination of dysuria and frequency without vaginal discharge or irritation had a likelihood ratio of 24.6. Patients who had recurrent UTI and made a self-diagnosis had a likelihood ratio of 4.0. This study seems to support the practice of treating uncomplicated cystitis in female patients based on history alone. Further diagnostic evaluation, including urinalysis and urine culture, should be performed in all patients who present with pyelonephritis or any complicated UTI, including complicated cystitis.

    Urine dipstick is often the first diagnostic test performed on a patient with urinary complaints. On a clean-catch urine specimen, leukocyte esterase (LE) is an enzyme released from white blood cells (WBCs). Nitrites, which are converted from urinary nitrates in the presence of certain bacteria or blood, may suggest the presence of a UTI. Taken alone, nitrite sensitivity on dipstick urinalysis (UA) is 81%, whereas LE sensitivity is 77%. If both are present, the sensitivity increases to 94%. It is important to note that nitrites are only present when infections are caused by the Enterobacteriaceae (eg, E coli), which convert urinary nitrate to nitrite. The absence of nitrites on a urine dipstick certainly does not exclude the presence of other common pathogens, which includes S. saprophyticus and enterococci. Nitrites are more specific for the diagnosis of UTI than LE (87% versus 54%) according to Rehmani (2004). This makes scientific sense considering the noninfectious conditions that can lead to pyuria, such as interstitial nephritis and pyelonephritis. In 2001, Lammers and colleagues found that if the urine dipstick definition of UTI was a positive LE and nitrite, the overtreatment rate for UTI was 47% and the undertreatment rate was 13%. This illustrates the inability of dipstick UA to predict UTI accurately. It is important to note that there are situations in which the urine nitrite may be falsely negative. These include: inadequate dietary nitrates can reduce substrates; vitamin C can prevent the proper chemical reaction to cause dipstick positivity; an old dipstick exposed to air may not properly undergo color change; unusually high urine urobilinogen or low urine pH (<6.0) urinary frequency may not allow enough time for conversion from nitrate to nitrite.

    Sending the urine to the laboratory for formal microscopic analysis (Urine Microscopy) is another tool available to assist with the diagnosis of UTI. Classically, the presence of more than five leukocytes (WBCs) per high-power field (hpf), more than five red blood cells (RBCs) per hpf, or more than 2+ bacteria is consistent with a diagnosis of UTI. In the study by Lammers and colleagues (2001) mentioned previously, it was discovered that by using a cutoff of more than three WBCs per hpf and more than five RBCs per hpf on the urinalysis, the overtreatment rate was 44% and the undertreatment rate was 11%. When comparing these findings with their findings regarding the urine dipstick, it is clear that the undertreatment and overtreatment rates are nearly the same. Given the increased cost and time involved in performing a formal microscopic analysis, the urine dipstick is the screening test of choice in most scenarios to make the diagnosis of UTI.

    Although Urine Gram Stain is not available in many settings, it is a sensitive and specific test. In a study done by Wiwanitkit and colleagues in 2005, the sensitivity of the urine Gram stain was found to be 96.2%, with specificity of 93.0%. These data were compared with the sensitivity and specificity of urine microscopy, which were 65.4% and 74.4%, respectively. The problem with this test is its lack of availability in many emergency departments and the increased time it may take to get the results. If available, however, the urine Gram stain can be quite enlightening to health care providers.


    Bent, S, et al. (2002). Does this woman have an acute uncomplicated urinary tract infection?. Journal of the American Medical Association (JAMA). 287(20):270110.

    Boie, E., Goyal, D., & Sadosty, A. (2005). Urinary tract infections. In: Wolfson A, editor. Clinical practice of emergency medicine. Philadelphia: Lippincott Williams & Wilkins.

    Gupta, K., Hooton, T.M., Stamm, W.E. (2001). Increasing antimicrobial resistance and the management of uncomplicated community-acquired urinary tract infections. Annals of Internal Medicine 135(1):4150.

    Krieger, J.N. (2002). Urinary tract infections: whats new?. Journal of Urology. 168(6):23518.

    Lammers RL, et al. (2001). Comparison of test characteristics of urine dipstick and urinalysis at various test cutoff points. Annals of Emergency Medicine. 38(5):50512.

    Rehmani R. (2004). Accuracy of urine dipstick to predict urinary tract infections in an emergency department. Journal of Ayub Medical College Abbottabad. 16(1):47.

    Wiwanitkit, V., Udomsantisuk, N., & Boonchalermvichian, C. (2005). Diagnostic value and cost utility analysis for urine Gram stain and urine microscopic examination as screening tests for urinary tract infection. Urology Research. 33(3):2202.

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    Post  nursing on Tue 02 Feb 2010, 5:47 am

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