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THE URINARY TRACT INFECTION IS GIVEN COURSE FOR FIRS AND SECOND YEAR MEDICINE STUDENTS
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- 2. Lecture objectives Tolist and describe the common microbes involved in urinary tract infection (UTI) To discuss the epidemiology, pathogenesis, clinical manifestation, diagnosis, and management of UTIs (particularly cystitis and pyelonephritis) 2
- 3. Overview : Structureof the urinary tract 3
- 4. Introduction to UrinaryTract Infections (UTIs) • UTI are some of the most common bacterial infections, affecting 150 million people each year worldwide1 . • UTIs are a significant cause of morbidity in infant boys, older men and females of all ages. • Serious sequelae include frequent recurrences, pyelonephritis with sepsis, renal damage in young children, pre-term birth • Complications caused by frequent antimicrobial use, such as high-level antibiotic resistance and Clostridium difficile colitis.
- 5. Introduction to UTI •Clinically, UTIs are categorized as uncomplicated or complicated. • Uncomplicated UTIs • Typically affect individuals who are healthy and have no structural or neurological urinary tract abnormalities • Typically affect women, children and elderly patients who are otherwise healthy.
- 6. Introduction : ComplicatedUTIs • are defined as UTIs associated with factors that compromise the urinary tract or host defense, including • Urinary obstruction • Urinary retention caused by neurological disease • Renal failure, renal transplantation • Immunosuppression, pregnancy • The presence of foreign bodies such as calculi, indwelling catheters or other drainage devices
- 7. Introduction: Catheter-associated UTIs(CAUTIs) • are associated with increased morbidity and mortality • are collectively the most common cause of secondary bloodstream infections. • Risk factors for developing a CAUTI include prolonged catheterization, female gender, older age and diabetes
- 8. Risk factors forUTI’s 8 FEMALE MALE • Sexual intercourse, Menopause, Pregnancy • Enlarged prostate gland • Few lactobacilli in vaginal mucosa, Douching • Congenital abnormalities that obstruct or slow urine flow • Immunosuppression, Diabetes mellitus • Diabetes mellitus • Use of diaphragm and spermicides • Immunosuppression
- 9. Risk factors forUTI’s 9 FEMALE MALE • Use of Foley catheters, Kidney stones • Kidney stone • Bladder or uterine prolapse • Use of catheters • Neurogenic bladder or bladder diverticulum • Neurogenic bladder • Congenital abnormalities that obstruct or Slow urine flow
- 10. UTIs can bedivided into 1.Upper tract infections, which involve the kidneys ( pyelonephritis) 2.Lower tract infections, which involve the bladder ( cystitis), urethra (urethritis), and prostate ( prostatitis). • However, infection often spreads from one area to the other.
- 11. Etiology of UTI •UTIs are caused by both Gram-negative and Gram- positive bacteria, as well as by certain fungi • The most common causative agent for both uncomplicated and complicated UTIs is • Uro-pathogenic Escherichia coli (UPEC).
- 12. Etiology of uncomplicatedUTIs • UPEC is followed in prevalence by • Klebsiella pneumoniae, Staphylococcus saprophyticus • Enterococcus faecalis, group B Streptococcus (GBS) • Proteus mirabilis, Pseudomonas aeruginosa • Staphylococcus aureus • Candida spp
- 13. Etiology of Forcomplicated UTIs •Following UPEC as most common • Enterococcus spp. • K. pneumoniae • Candida spp. • S. aureus • P. mirabilis • P. aeruginosa and GBS
- 14.
- 15. List of commonmicrobes…. Anaerobic & fastidious organisms are rarely cause UTI When there has been hematogenous spread to the urinary tract, other species may be found e.g. S. typhi, S. aureus and M. tuberculosis (renal tuberculosis) 15
- 16. Viral etiology ofUTIs Viral causes of UTI appear to be rare A number of viruses particularly mumps virus, CMV, and coxsackieviruses can be present in the kidneys and urine but rarely cause symptoms or any consequences Adenoviruses have been strongly implicated as causative agents in hemorrhagic cystitis in pediatric patients 16
- 17. Normal Microbiota ofthe UTI • The urethra normally supports the growth of some microbiota, chiefly avirulent species of Lactobacillus, Staphylococcus, and Streptococcus. • Occasionally other bacteria such as species of Mycobacterium, Bacteroides, Fusobacterium, and Peptostreptococcus colonize the distal end of a urethra. • The rest of the urinary organs and the urine in them are sterile due to the normally acidic pH of urine and the flushing action of urination.
- 18. Normal Microbiota ofthe UTI • Microbiota of a urethra do contaminate urine during urination • normally voided urine contains some bacteria, whereas urine collected directly from a urinary bladder is typically sterile.
- 19. Normal Microbiota ofthe UTI • A vagina is home to a wide assortment of microorganisms that vary with the levels of hormones, particularly estrogen. • When estrogen levels rise, such as occurs at puberty, cells lining a vagina produce glycogen, a polysaccharide that lactobacilli convert into lactic acid. • Acidity inhibits the growth of many opportunistic pathogens.
- 20. Normal Microbiota ofthe UTI • Prepubescent girls, who have little circulating estrogen, are more susceptible to vaginal infections. • Likewise, as estrogen levels fall and rise during the menstrual cycle, some women cycle between periods of infection and periods of health.
- 21. Virulence factors 1. specificfimbriae (pili) enable adherence to urethral and bladder epithelium(the presence of similar adhesins for uroepithelial cells) 2. The capsular acid polysaccharide (K) antigens are associated with the ability to cause pyelonephritis and are known to enable E. coli strains to resist host defenses by inhibiting phagocytosis. 21
- 22. Virulence factors 3. Hemolysinproduction by E. coli is linked with the capacity to cause kidney damage; many hemolysins act more generally as membrane- damaging toxins 4. The production of urease by organisms such as Proteus spp. has been correlated with their ability to cause pyelonephritis and stones 22
- 23. Pathogenesis of urinarytract infections 1. Uncomplicated UTI begin when uropathogens that reside in the gut contaminate the periurethral area and are able to colonize the urethra. 2. Subsequent migration to the bladder and expression of pili and adhesins results in colonization and invasion of the superficial umbrella cells. 3. Host inflammatory responses, including neutrophil infiltration, begin to clear extracellular bacteria.
- 24. Pathogenesis of urinarytract infections • Some bacteria evade the immune system, either through host cell invasion or through morphological changes that result in resistance to neutrophils, and these bacteria undergo multiplication and biofilm formation.
- 25. Pathogenesis of urinarytract infections • Those bacteria produce toxins and proteases that induce host cell damage, releasing essential nutrients that promote bacterial survival and ascension to the kidneys. • Untreated UTIs can ultimately progress to bacteraemia.
- 26. Pathogenesis of urinarytract infections
- 27. Urethritis • Infection ofthe urethra with bacteria (or with protozoa, viruses, or fungi) occurs portions of the male urethra and in the entire female urethra. • The sexually transmitted pathogens Chlamydia trachomatis, Neisseria gonorrhoeae , Trichomonas vaginalis , and herpes simplex virus are common causes in both sexes.
- 28. Urethritis • In acuteurethral syndrome, routine urine cultures are either negative or show colony counts that are lower than the traditional criteria for diagnosis of bacterial cystitis. • Urethritis is a possible cause because causative organisms include • Chlamydia trachomatis and Ureaplasma urealyticum • which are not detected on routine urine culture.
- 29. Cystitis • is acommon inflammation of the urinary bladder in females. • Symptoms often include dysuria (difficult, painful, urgent urination) and pyuria. • The female urethra is less than 2 inches long, and microorganisms traverse it readily. • It’s also closer than the male urethra to the anal opening and its contaminating intestinal bacteria.
- 30. Cystitis • These considerationsare reflected in the fact that the rate of UTI in women is eight times that of men. • In either gender, most cases are due to infection by E. coli, which can be identified by cultivation on differential media such as MacConkey’s agar. • Another frequent bacterial cause is the Staphylococcus saprophyticus.
- 31. Pyelonephritis • In 25%of untreated cases, cystitis may progress to pyelonephritis, an inflammation of one or both kidneys. • Symptoms are fever and flank or back pain. • In females, it’s often a complication of lower urinary tract infections.
- 32. Pyelonephritis • The causativeagent in about 75% of the cases is E. coli. • Pyelonephritis generally results in bacteremia • blood cultures and a Gram stain of the urine for bacteria are useful for diagnosis. • If pyelonephritis becomes chronic, scar tissue forms in the kidneys and severely impairs their function.
- 33. Pyelonephritis • Because pyelonephritisis a potentially life- threatening condition • Treatment usually begins with • Intravenous, extended-term administration of a broad spectrum antibiotic • Such as a second- or third-generation cephalosporin.
- 34. • Proteus speciesare found in the intestinal tract of humans and animals, soil, sewage and water. They are motile, non-capsulated and pleomorphic rods. Species of medical importance are: - P. mirabilis - P. vulgaris Genus Proteus
- 35. Virulence factors 1.These bacteriaare characteristically highly motile and chemotaxis may play a part in pathogenesis. 2.Haemolysins 3.A range of proteases such as an IgAase. 4.Proteus species produce urease Genus Proteus
- 36. Pathogenesis and clinicalmanifestations Proteus mirabilis causes: • Urinary infections. • is a common cause of UTI in the elderly and young males and often following catheterization or cystoscopy. • Infections are also associated with the presence of renal stones.
- 37. •Habitat: skin andmucosal membranes of the genitourinary tract •Common cause of urinary tract infections in young, sexually active females Coagulase-Negative Staphylococci: Staphylococcus saprophyticus
- 38. Leptospirosis • It isprimarily a disease of domestic or wild animals • Sometimes causes severe kidney or liver disease. • The causative agent is the spirochete Leptospira interrogans • It’s an obligate aerobe.
- 39. Leptospirosis • Humans becomeinfected by contact with urine- contaminated water from freshwater lakes or streams, soil, or sometimes with animal tissue. • People whose occupations expose them to animals or animal products are most at risk.
- 40. Leptospirosis • Infections havebeen associated with recreational water sports. • Usually the pathogen enters through minor abrasions in the skin or mucous membranes. • When ingested, it enters through the mucosa of the upper digestive system.
- 41. Leptospirosis • In asmall number of cases the kidneys and liver become seriously infected (Weil’s disease). • Weil’s disease, or syndrome: • This term is occasionally used to describe the severe form of leptospirosis in which there is liver damage with jaundice and renal failure. • Kidney failure is the most common cause of death
- 42. Diagnosis • Urinalysis • Sometimesurine culture • Diagnosis by culture is not always necessary. • If done, diagnosis by culture requires demonstration of significant bacteriuria in properly collected urine.
- 43. Urine collection • Urinecollection is then by clean-catch or catheterization. • To obtain a clean-catch, midstream specimen • The first 5 mL of urine is not captured; the next 5 to 10 mL is collected in a sterile container. • A specimen obtained by catheterization is preferable in older women (who typically have difficulty obtaining a clean-catch specimen) and in women with vaginal bleeding or discharge.
- 44. Urine testing • Microscopicexamination of urine is useful but not definitive. • Pyuria is defined as ≥ 8 WBCs/μL of uncentrifuged urine, which corresponds to 2 to 5 WBCs/high- power field in spun sediment. • Most truly infected patients have > 10 WBCs/μL.
- 45. Microscopic urinalysis: Pyuria (WBC’s), Hematuria (RBC’s), Bacteriuria Pyuria Hematuria Bacteriuria Investigation Bacteriuria Pyuria
- 46. Urine testing • Thepresence of bacteria in the absence of pyuria, especially when several strains are found, is usually due to contamination during sampling. • WBC casts indicate only an inflammatory reaction; they can be present in pyelonephritis, glomerulonephritis.
- 47. Dipstick tests • Apositive nitrite test is highly specific for UTI. • The leukocyte esterase test is very specific for the presence of > 10 WBCs/μL and is fairly sensitive. • In adult women with uncomplicated UTI with typical symptoms, most clinicians consider positive microscopic and dipstick tests sufficient.
- 48. Cultures • are recommendedin patients whose characteristics and symptoms suggest complicated UTI or an indication for treatment of bacteriuria. • Common examples include the following: • Pregnant women • Postmenopausal women • Prepubertal children • Patients with urinary tract abnormalities or recent instrumentation • Patients with immunosuppression • Patients whose symptoms suggest pyelonephritis or sepsis • Patients with recurrent UTIs (≥ 3/yr)
- 49. Cultures : Forasymptomatic bacteriuria • Two consecutive clean-catch, voided specimens from which the same bacterial strain is isolated in colony counts of >105 /mL • Among women or men, in a catheter-obtained specimen, a single bacterial species is isolated in colony counts of > 102 /mL
- 50. Cultures : Forsymptomatic Patients • Uncomplicated cystitis in women: > 102 /mL • Acute, uncomplicated pyelonephritis in women: > 104 /mL • Complicated UTI: > 105 /mL in women; or > 104 /mL in men or from a catheter-derived specimen in women • Acute urethral syndrome: > 102 /mL of a single bacterial species
- 51. Management of UncomplicatedUTI • is treated with an oral Antibacterial as a single dose or for 3 days • Sulfonamides and trimethoprim alone or in combination with sulfamethoxazole, a fluoroquinolone, and nitrofurantoin are the agents most commonly used 51
- 52. Management of complicatedUTI should be treated with a systemic antibacterial agent The organism should be known to be susceptible to the antibacterial, and systemic treatment should continue until the signs and symptoms subside. It can then be replaced by oral therapy. 52
- 53. Management of UTI…. Theusual length of treatment is at least 10 days, but longer treatment may be necessary to sterilize the kidney Recurrent infections in healthy women can be prevented by regularly emptying the bladder. This washes bacteria out of the urinary tract and is particularly important following intercourse. 53
- 54. Management of UTI…. Theprophylactic use of antibiotics may also prevent recurrent infections, but in the presence of underlying abnormalities there is a tendency to select antibiotic- resistant strains. 54
- 55. Strategies to PreventUTI • Increase Fluid intake • Void before and after intercourse • Personal Hygiene (wipe front to back) • Avoid feminine hygiene sprays • Take showers instead of baths • Cranberries / Juice • Cranberries
- 56.
Editor's Notes
- #15 Fastidious bacteria are the one that need blood for their growth on culture
- #16 Fastidious bacteria are the one that need blood for their growth on culture
- #21 The healthy urinary tract is resistant to bacterial colonization. With the exception of the urethral mucosa, the urinary tract usually eliminates microorganisms rapidly and efficiently. The pH, chemical content and flushing mechanism of urine help to dispose of organisms in the urethra. Although urine is a good culture medium for most bacteria, it is inhibitory to some, and anaerobes and other species (non-hemolytic streptococci, corynebacteria and staphylococci), which comprise most of the normal urethral flora, do not readily multiply in urine. The role of humoral immunity in the host's defense against infection of the urinary tract is poorly understood. After infection of the kidney, IgG and secretory IgA antibodies can be detected in urine, but the protective role of these antibodies against subsequent infection is unclear. Infection of the lower urinary tract is usually associated with a low or undetectable serologic response, reflecting the superficial nature of the infection; the bladder and urethral mucosa are rarely invaded in UTIs
- #22 The healthy urinary tract is resistant to bacterial colonization. With the exception of the urethral mucosa, the urinary tract usually eliminates microorganisms rapidly and efficiently. The pH, chemical content and flushing mechanism of urine help to dispose of organisms in the urethra. Although urine is a good culture medium for most bacteria, it is inhibitory to some, and anaerobes and other species (non-hemolytic streptococci, corynebacteria and staphylococci), which comprise most of the normal urethral flora, do not readily multiply in urine. The role of humoral immunity in the host's defense against infection of the urinary tract is poorly understood. After infection of the kidney, IgG and secretory IgA antibodies can be detected in urine, but the protective role of these antibodies against subsequent infection is unclear. Infection of the lower urinary tract is usually associated with a low or undetectable serologic response, reflecting the superficial nature of the infection; the bladder and urethral mucosa are rarely invaded in UTIs