Urinary Tract Infection And Serodiagnosis Essay
Urinary Tract Infection And Serodiagnosis Essay
What are the three ways in which urinary tract infections may be acquired?
Answer: The three ways in which urinary tract infections may be acquired are:
Sexual Contact: Sexual contact will not only lead to sexually transmitted diseases (STDs), but may also lead to urinary tract infections. Cystitis, vaginitis, urethritis or acute urethral infection can be a common occurrence in the presence of bacterias like E.coli or Chlamydia trachomatis. symptoms will be burning, itching, increased frequency of micturition (Najar, Saldahna, Banday, 2009) . Having sexual contact with a person affected with Urinary tract infection of any kind, increases the risk of contacting the infection manifolds.Urinary Tract Infection And Serodiagnosis Essay. The unaffected partner gets exposed to the microorganism and thus develops increased proneness to infection.
Decreased urinary flow: Inadequate intake of water, neurogenic bladder and obstruction in the outflow of the urine due to any cause like prostatitis, carcinoma, tumor like growth etc., may increase the susceptibility towards development of the urinary tract infection. The altered chemical balance will favor the growth of the microbes in the periurethral region thus leading to development of infection.
Catheterization: Insertion of catheters following urinary flow impedances or obstruction increases the risk of Urinary tract infection. The reasons are many, like insertion of a catheter is introduction of a foreign body into the urethra, thus evoking a response from the body. Another cause is insertion into the urethra drags the microbes up, back into the urethra instead of propelling them forward and helping in their expulsion (Aunet.org, 2015).
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What are the primary and secondary antibody responses to an immunogenic response? Describe.
Answer: Primary antibody response is the response generated by the body on the first instance of exposure to a particular antigen. The body starts forming antibodies few days after the exposure. This time taken is known as the latent period. The patient thus has to face the initial sufferings post the first attack by the antigen.
Whereas the secondary antibody response is the response that develops at the second or subsequent exposure with a particular antigen. The body now becomes adjusted, it has stored antibodies that were formed during the first exposure.Urinary Tract Infection And Serodiagnosis Essay. Those cells have the so-called :memory” which enables them to fight with the antigen on their further entry into the body(Primary and secondary antibody responses, 2014).
What is the importance of acute and convalescent serum specimens for the serologic diagnosis of infection? Explain.
Answer: Acute sera is the serum of the patient the is obtained from the patient during the course of his illness, the serum thus obtained is the one which is freshly obtained from and infected patient. Whereas, the convalescent serum is the serum that is taken out of the patient after he has recovered from a certain illness, it is usually the time period almost 4 weeks after the treatment of that particular disease that the serum is said to be convalescent (Answers.com, 2015). Both the types will demonstrate rich number of antigens present in them, thus helping in the diagnosis of the disease. The titres are indicative of the severity if the disease. Thus the levels are required to be known prior to the treatment of the diseases and hence the tests are essential for the diagnosis and prognosis of the case in question.Urinary Tract Infection And Serodiagnosis Essay. A check on the titres will be indicative of the efficacy of the prescribed treatment thus making it easier to give the right diagnosis and prognosis of the concerned case.
REFERENCES
Answers.com,. (2015). What are acute and convalescent sera. Retrieved 7 February 2015, from http://www.answers.com/Q/What_are_acute_and_convalescent_sera
Auanet.org,. (2015). Adult UTI: American Urological Association. Retrieved 7 February 2015, from https://www.auanet.org/education/adult-uti.cfm
Najar, M., Saldanha, C., & Banday, K. (2009). Approach to urinary tract infections. Indian J Nephrol,19(4), 129. doi:10.4103/0971-4065.59333
Primary and Secondary Antibody Responses. (2014). Boundless. Retrieved from https://www.boundless.com/microbiology/textbooks/boundless-microbiology-textbook/immunology-11/antibodies-141/primary-and-secondary-antibody-responses-719-6154/
Urinary tract infection and asymptomatic bacteriuria are common in older adults. Unlike in younger adults, distinguishing symptomatic urinary tract infection from asymptomatic bacteriuria is problematic, as older adults, particularly those living in long-term care facilities, are less likely to present with localized genitourinary symptoms. Consensus guidelines have been published to assist clinicians with diagnosis and treatment of urinary tract infection; however, a single evidence-based approach to diagnosis of urinary tract infection does not exist. In the absence of a gold standard definition of urinary tract infection that clinicians agree upon, overtreatment with antibiotics for suspected urinary tract infection remains a significant problem, and leads to a variety of negative consequences including the development of multidrug-resistant organisms. Future studies improving the diagnostic accuracy of urinary tract infections are needed. This review will cover the prevalence, diagnosis and diagnostic challenges, management, and prevention of urinary tract infection and asymptomatic bacteriuria in older adults. Urinary Tract Infection And Serodiagnosis Essay.
Definitions
Urinary tract infection (UTI) is broadly defined as an infection of the urinary system, and may involve the lower urinary tract or both the lower and upper urinary tracts [1]. The definition of a symptomatic UTI generally requires the presence of urinary tract-specific symptoms in the setting of significant bacteriuria with a quantitative count of ≥105 colony forming units of bacteria per milliliter (CFU/ml) in one urine specimen [2,3]. Asymptomatic bacteriuria (ASB) is defined as the presence of bacteria in the urine, without clinical signs or symptoms suggestive of a UTI [2]. Asymptomatic pyuria is defined as the presence of white blood cells in the urine, in the absence of urinary tract specific-symptoms.
Incidence & prevalence of UTI & ASB
UTI is one of the most commonly diagnosed infections in older adults. It is the most frequently diagnosed infection in long-term care residents, accounting for over a third of all nursing home-associated infections [4,5].Urinary Tract Infection And Serodiagnosis Essay. It is second only to respiratory infections in hospitalized patients and community-dwelling adults over the age of 65 years [6,7]. As our population ages, the burden of UTI in older adults is expected to grow, making the need for improvement in diagnostic, management and prevention strategies critical to improving the health of older adults.
Urinary tract infection
The incidence of UTI is higher in women compared with men across all age groups. UTI is frequent in young sexually active women with reported incidence rates ranging from 0.5 to 0.7 per person-year [8], while in young men aged 18–24, the reported incidence of UTI is 0.01 per person-year [9]. The incidence of UTI decreases during middle age but rises in older adults [10–12]. Over 10% of women older than 65 years of age reported having a UTI within the past 12 months [11]. This number increases to almost 30% in women over the age of 85 years [12]. In a large prospective cohort study of post-menopausal women living in the community, the incidence of UTI was 0.07 per person-year and 0.12 per person-year in older women with diabetes [10]. For men aged 65–74 years, the incidence of UTI is estimated to increase to 0.05 per person-year [9]. In both men and women over the age of 85 years, the incidence of UTI increases substantially. A small cohort study in this age group found the incidence of UTI in women to be 0.13 per person-year and 0.08 per person-year in men [13].
Although several estimates exist in the literature, accurately measuring the incidence of UTI in the elderly is challenging since criteria used for diagnosis are not consistent across epidemiologic studies. Furthermore, differentiating UTI from ASB is difficult and misclassification may occur. Urinary Tract Infection And Serodiagnosis Essay.
Asymptomatic bacteriuria
In contrast to UTI, ASB is more common in older adults than in younger adults. The prevalence increases considerably with age in both men and women. In younger women, the estimated prevalence of ASB is 1–5%, increasing to an estimated 6–16% in women over the age of 65 years [2,14,15]. In women over the age of 80 years living in the community, the incidence is reported to be almost 20% [16]. In long-term care facilities, the prevalence is even higher with estimates in women ranging from 25 to 50% [3]. In young ambulatory men, ASB is uncommon with reported prevalence rates between 0 and 1.5% [17]; however, in men over the age of 80 years, the prevalence is estimated to increase to almost 10% [16]. In aging men residing in long-term care facilities, the prevalence of ASB approaches that of women, ranging from 15 to 35% [3]. The use of urinary catheters predisposes both men and women to ASB. The risk in catheterized older adults ranges from 3 to 10% per day of catheterization, eventually reaching 100% in adults with chronic indwelling catheters [14,18]. Pyuria in combination with bacteriuria is common in both younger and older adults. The prevalence of pyuria in women with bacteriuria is estimated to be 32%, increasing to 90% in elderly men and women [17].
Risk factors associated with UTI
Risk factors for developing symptomatic UTI in the aging population are different to those in younger women. Age-associated changes in immune function, exposure to nosocomial pathogens and an increasing number of comorbidities put the elderly at an increased risk for developing infection [19].
Community-dwelling older adults
Several risk factors associated with UTI in post-menopausal women have been identified, many of which are similar to younger sexually active women. The most consistent and strongest predictor across all age groups is having a history of UTI [10,20,21]. In one study, postmenopausal women with a prior UTI were over four-times more likely to develop a subsequent infection compared with women without a previous diagnosis [20]. In women with over six lifetime UTIs, the risk of developing a subsequent UTI is over seven-times higher than women without a prior history of UTI [10]. Urinary Tract Infection And Serodiagnosis Essay. Diagnosis of UTI, specifically before the age of 15 years, has also been shown to increase the risk in postmenopausal women, suggesting that genetic factors may predispose certain women to recurrent infections [21].
The relationship between sexual activity and UTI is well established in younger women, although the association in postmenopausal women is not as clear. During intercourse, vaginal bacteria gain access to the urinary tract by colonizing the periurethral mucosa and ascending to the bladder through the urethra [22]. A cohort study in 2008 by Moore et al. reported an increase in risk of developing UTI in post-menopausal women who reported intercourse 2 days prior to onset of symptoms (hazard ratio: 3.42; 95% CI: 1.49–7.80). This increased risk of UTI was not demonstrated for those women reporting intercourse 1 day prior (hazard ratio: 1.01; 95% CI: 0.30–3.37) or >2 days prior (hazard ratio: 0.95; 95% CI: 0.52–1.72), making the clinical significance of this finding unclear [23]. Although up to 65% of postmenopausal women report being sexually active [24], most studies have not consistently found intercourse to be a strong predictor for UTI in this population [10,21,23].
Urinary retention and high postvoid residual (PVR) urine has been postulated to be a risk factor for UTI in older adults. In men, prostatic hypertrophy causing obstruction to the normal flow of urine leads to high PVR. High PVR and urinary stasis as a result of chronic obstruction are thought to be important factors for developing UTI and ASB in older men; however, studies evaluating the association in this population are limited.Urinary Tract Infection And Serodiagnosis Essay. In women, the association between high PVR and UTI has been more thoroughly examined, although data from several studies have yielded conflicting results. A 2011 cohort study of postmenopausal women did not find high PVR (>200 ml) to increase the 1-year risk of UTI in a multivariate analysis, although PVR >200 ml was associated with more frequent urinary symptoms [25].
Institutionalized older adults
Institutionalized adults generally have more functional impairments, higher rates of cognitive deficits and a greater number of medical comorbidities compared with older adults living in the community. All of these characteristics predispose this population to higher rates of ASB and UTI [26]. The most significant risk factors associated with UTI in institutionalized older adults are the presence of a urinary catheter and, similar to community-dwelling older adults, history of prior UTI [3,13,27]. Medical comorbidities, such as stroke and dementia, which may predispose individuals to bowel and bladder incontinence, have been associated with symptomatic UTI and persistent ASB in this population [13,26]. Other predictive factors include disability in activities of daily living and having a history of urinary incontinence [13]. Similar to women in the community, high PVR has not been associated with UTI in nursing home residents [28]. ASB, which is most common in nursing home residents and catheterized adults, has been associated with an increased risk of symptomatic UTI in a few studies [10,29]. Urinary Tract Infection And Serodiagnosis Essay.
Diagnosis of UTI & ASB
Community-dwelling older adults
UTI in healthy older women without a urinary catheter or abnormalities of the genitourinary tract is generally regarded as uncomplicated [30]. Diagnosis follows the same algorithm used in younger patients, requiring the presence of genitourinary symptoms and a positive urine culture. Common urinary symptoms suggestive of cystitis include urgency, frequency, dysuria and supra-pubic tenderness. However, postmenopausal women may also present with nonspecific generalized symptoms, such as lower abdominal pain, back pain, chills and constipation [24].
ASB in women is defined as the presence of two consecutive urine specimens positive for the same bacterial strain in quantities ≥105CFU/ml, in the absence of any signs or symptoms of a genitourinary tract infection. For men, ASB is defined as a single voided specimen with one bacterial isolate in quantities ≥105 CFU/ml, in the absence of symptoms [2].Urinary Tract Infection And Serodiagnosis Essay. For adults with an indwelling urethral, suprapubic or intermittent catheter, ASB is defined as a positive urinary culture for one bacterial isolate in quantities ≥102 CFU/ml, in the absence of symptoms [31]. Although ASB is common in older adults, it has not been associated with adverse clinical outcomes, thus routine screening is not recommended [2,32].
Institutionalized older adults & catheterized patients
Similar to other populations, the diagnosis of symptomatic UTI in nursing home residents requires the presence of genitourinary symptoms in the setting of a positive urine culture. In older adults who are cognitively intact, the diagnosis of symptomatic UTI is relatively straightforward. However, nursing home residents often suffer from significant cognitive deficits, impairing their ability to communicate, and chronic genitourinary symptoms (e.g., incontinence, urgency and frequency), which make the diagnosis of symptomatic UTI in this group particularly challenging. Furthermore, when infected, nursing home residents are more likely to present with nonspecific symptoms, such as anorexia, confusion and a decline in functional status [33]; fever may be absent or diminished [19]. In the setting of atypical symptoms, providers are often faced with the challenge of differentiating a symptomatic UTI from other infections or medical conditions. The high prevalence of bacteriuria plus pyuria in this population often leads to the diagnosis of UTI.Urinary Tract Infection And Serodiagnosis Essay. Although bacteriuria plus pyuria is necessary for diagnosis of a laboratory-confirmed UTI, alone it is not sufficient for making the diagnosis of symptomatic UTI. To date, universally accepted criteria for diagnosing UTI in this population do not exist, making it difficult for providers to distinguish a symptomatic UTI from other conditions in the presence of new nonspecific symptoms.
To aid clinicians in diagnosing symptomatic UTI, several consensus guidelines have been published standardizing definitions for symptomatic UTI in long-term care facilities. In 2001, Loeb et al. proposed a set of guidelines aimed to assist providers with clinical decision-making by providing recommendations on the minimum criteria needed for initiation of antibiotics in nursing home residents [34]. The Loeb criteria for diagnosing UTI are outlined in Table 1. In 1991, McGeer et al. first developed consensus-based guidelines aimed at standardizing infection definitions for surveillance and research activities in long-term care facilities [35]. Although commonly used by regulating agencies and infection control practitioners for reporting purposes, these consensus definitions, known as the McGeer criteria, were never validated [36]. In 2012, members of the Society for Healthcare Epidemiology of America, assembled to update the current guidelines. Significant changes were made to the definition of UTI for residents with and without a urinary catheter. Most notably, the new definitions require a positive urinary culture in both residents with and without an indwelling urinary catheter, or the presence of a positive blood and urine culture in residents without localized symptoms of UTI [37]. Table 1 provides a comparison of three published consensus definitions. The diagnostic accuracy of these guidelines has not yet been validated. Urinary Tract Infection And Serodiagnosis Essay.
Table 1
Comparison of consensus criteria for diagnosis of symptomatic urinary tract infection in residents with and without an indwelling urinary catheter.
| SHEA/CDC 2012 (revised McGeer criteria) [37] | McGeer criteria 1991† [35] | Loeb criteria [34] |
|---|---|---|
| Without an indwelling urinary catheter | ||
|
|
||
| Swelling or tenderness of the testes, epididymis or prostate or: Fever or leukocytosis and at least one of the following or:
|
Three of the following criteria:
|
Acute dysuria alone or: Fever (>37.9° or 1.5°C increase in baseline) plus one of the following:
|
|
|
||
| With an indwelling urinary catheter | ||
|
|
||
One of the following criteria:
|
Two of the following criteria:
|
At least one of the following:
|
SHEA: Society for Healthcare Epidemiology of America.
Although guidelines proposed by Loeb et al. are commonly accepted, applying these criteria to clinical practice in the nursing home population is challenging and the overuse of antibiotics remains a significant problem [36]. A major challenge clinicians face when diagnosing UTI is the relative low frequency of localized genitourinary symptoms (i.e., dysuria, frequency and urgency) found in nursing home residents, many of which are necessary components of the Loeb criteria. In a recent study of nursing home residents with advanced dementia, mental status change was the most common reason for suspected UTI, accounting for over 40% of cases; localized genitourinary symptoms were infrequent. Dysuria was responsible for only 3.8% of suspected cases, urinary frequency for 1.5% of cases, and no suspected cases of UTI were due to urgency or suprapubic pain. In this study, 85% of suspected UTIs did not meet criteria for antimicrobial initiation; however, most individuals (75%) were treated with antibiotics [38]. This study illustrates that, although criteria exist for assisting clinicians with diagnosis and treatment of UTI, providers caring for this population may be hesitant to follow them. Furthermore, it highlights the overall low prevalence of typical genitourinary symptoms in severely demented patients with suspected UTI. Further studies are needed to improve and test current clinical criteria used for symptomatic UTI diagnosis, specifically in a population that is often unable to verbalize genitourinary symptoms.
In 2007, a cohort study in nursing home residents attempted to identify clinical features that were predictive of bacteriuria plus pyuria. Although bacteriuria plus pyuria alone is not diagnostic of a symptomatic UTI, their presence signifies a host inflammatory response in the presence of a microbial pathogen, both of which are a necessary components to the diagnosis of UTI. The most commonly reported clinical features for suspected UTI in this cohort were change in mental status (39%), change in behavior (19%), change in character of the urine (i.e., gross hematuria and change in the color or odor of urine; 15.5%), fever or chills (12.8%) and change in gait or a fall (8.8%) [39]. Although change in mental status and change in behavior are commonly reported by providers, only three measures of mental status (i.e., periods of altered perception, disorganized speech and lethargy) and one measure of behavior (i.e., resists care) have been shown to be reliably assessed by providers caring for nursing home residents [40]. In a multivariable analysis, change in mental status, dysuria and change in character of the urine were significantly associated with the outcome of bacteriuria plus pyuria. Urinary Tract Infection And Serodiagnosis Essay. Dysuria alone predicted 39% of cases with confirmed bacteriuria plus pyuria; however, in combination with either change in mental status or change in character of the urine, the predicted probability increased to 63% [39]. This predicted probability is higher than the Loeb criteria, which had a positive predictive value of 57% for detecting bacteriuria plus pyuria [41]. When all three clinical features were present, the predicted probability increased to 100%, but all three clinical features were only present in four episodes of suspected UTI. This suggests that a combination of nonspecific and urinary tract-specific symptoms (e.g., change in mental status, change in character of the urine and dysuria) may be useful in clinically assessing nursing home residents with UTI [39,41]. Nonspecific symptoms, when present alone, however, have not been shown to correlate with bacteriuria [42]. Future prospective cohort studies validating the proposed combination of clinical features in diagnosing symptomatic UTI in older adults are needed. Falls are common in older adults and often prompt empiric antibiotic use for suspected UTI. Although falls have been previously associated with UTI in few studies, a recent report found that 80% of fall episodes were not associated with bacteriuria plus pyuria [43,44].
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The diagnosis of UTI remains a significant diagnostic dilemma for clinicians caring for older adults. Fever and localized urinary symptoms should still be the initial trigger for UTI evaluation. According to the Infectious Disease Society of America guidelines, the minimum laboratory evaluation for suspected UTI should include urinalysis for determination of leukocyte esterase and nitrite level by use of dipstick, and a microscopic examination for white blood cells. If the urinary dipstick is negative for leukocyte esterase and nitrite in a nursing home resident, the negative predictive value is 100% and further evaluation can be halted [45]. If pyuria or a positive leukocyte esterase or nitrite is present, urine culture should be obtained and, if positive, antibiotics for suspected UTI should be considered [33]. Urinary Tract Infection And Serodiagnosis Essay. Figure 1 represents a modification by the authors of the revised McGeer criteria, which can be used by clinicians as a guide for clinical management. In the revised figure, we incorporate the use of urinary dipstick for leukocyte esterase and nitrite testing as part of the initial evaluation for suspected UTI as per the Infectious Disease Society of America guidelines [33]. In addition, we expanded the definition of symptomatic UTI to include a combination of urinary-specific symptoms and -nonspecific symptoms (e.g., change in mental status or change in character of the urine), as this has been shown to predict bacteriuria plus pyuria in nursing home residents [39]. The modifications present in Figure 1, however, have not been validated. Future prospective studies are needed to validate this algorithm for use in diagnosis of UTI. Urinary Tract Infection And Serodiagnosis Essay.
