Microbiology of Renal system for medicine students (1).pptx

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1. Microbiology Renal system/ Urinary System By: Kasahun B. (MSc.) 4/11/2024 1

2. Module outline Introduction to urinary system Epidemiology of UTI Etiologic agents of UTI Clinical manifestation and pathogenesis of UTI Defense mechanism of urinary tract system Normal flora of urinary tract system Microbial causes of the kidney and UTI Urethritis Cystitis Pyelonephritis Risk factors of UTI Urinalysis Physical Chemical Microscopic analysis of urine Urine culturing and antibiotic susceptibility test 4/11/2024 2

3. Introduction What is renal system? It is one of excretory system that removes metabolic waste from our blood in the form of urine . The renal system , also known as the urinary system , consists of the kidneys, ureters, bladder, and the urethra .  4/11/2024 3

4. The urinary system is composed of: 1.Two kidneys  Filter blood plasma  Reabsorb most of water and solute  Excrete the remaining water and solute as urine 2. Paired ureters  transport urine from the kidneys to the bladder 3.Urinary bladder  provides a temporary storage for urine 4.Urethra  transports urine from the bladder out of the body 4/11/2024 4

5. Introduction… In males the urethra is also the terminal organ of the reproductive tract, But in females the urethra is separate from the vagina. 4/11/2024 5

6. Definitions of terminiologies UTIs : An infection in any part of the urinary system, the kidneys, bladder or urethra. Pyuria : is a condition defined by the increased presence of white blood cells in urine. Bacteriuria : i s the presence of bacteria in the urine  Reinfection : new infection after the previous one was completely eradicated. Recurrent UTIs : are defined as two episodes of acute bacterial cystitis, along with associated symptoms within the last six months or three episodes within the last year. Relapse UTIs : infection occurs when the same organism is not eradicated from the urine after 2 weeks despite appropriate antimicrobial treatment . 4/11/2024 6

7. Epidemiology of UTI In US, UTI is the second most common infection in humans next to the respiratory tract infection. UTIs occur in two general settings: Community acquired UTI, and Hospital acquired UTI; most often being associated with catheterization, which is known as CA UTIs. NB: Hospital-acquired UTIs, although less common than community acquired, It contribute about 40% to overall nosocomial infection rates. 4/11/2024 7

8. Epidemiology… It is estimated that 20-40% of the female population get infected with UTI in their lifetime. Patients of both sexes who have urinary catheters are susceptible to infections with a variety of microorganisms A single catheter have an infectious risk of 1% , and at least 10% of individuals with indwelling catheters become infected. 4/11/2024 8

9. Epidemiology… 4/11/2024 9

10. Epidemiology… UTI is common in women than in males ( Female to male ratio is 30:1), due to The shorter length of the female urethra and, Anatomic proximity of urethra to perianal areas making contamination likely 4/11/2024 10

11. UTI in women 4/11/2024 11

12. Route of transmission Ascending route: Urethra – Bladder – Kidney It is the most common route of UTIs. The urethra is usually colonized with bacteria. Massage of the urethra in women & sexual intercourse can force bacteria into the female bladder. 12 4/11/2024 Kidney & Urinary System, Microbiology

13. Hematogenous route: Infection of the renal parenchyma by bloodborne organisms clearly occurs in humans. Kidney is frequently the site of abscesses in patients with S . aureus bacteremia or endocarditis , or both. Lymphatic route The fact; Increased pressure in the bladder can cause lymphatic flow to be directed toward the kidney. Ascending pathway of infection is most common. 13 4/11/2024 Kidney & Urinary System, Microbiology

14. Pathogenesis of urinary tract infections. 4/11/2024 14

15. Pathogenesis and virulence factors of uropathogens Most UT pathogens originate in the fecal flora . Only aerobic & facultative species colonize and infect the urinary tract. E. coli possess the attributes required for UTI. UTI caused by certain sero groups of E. coli ; O (somatic) serotypes O1, O2, O4, O6, O7 & O75 K (capsular) serotypes K1, K2, K3, K5, K12 & K13. 15 4/11/2024 Kidney & Urinary System, Microbiology

16. virulence factors Pilli /-Fimbriae It is used for binding of E. coli to epithelial cell receptors containing globoseries glycosphingolipid. It accounts for the attachment of most strains causing kidney infection. Fimbriae attaching to globoseries receptors are termed P fimbriae; b/c the receptor is a constituent of the P blood group antigen complex present in uroepithelial cells. 16 4/11/2024 Kidney & Urinary System, Microbiology

17. Other virulence factors Flagellae They are necessary for motility. Motility facilitate ascending infection. Hemolysin It induces formation of pores in the cell membrane. Bacterial endotoxin It decrease urethral peristalsis. Bacterial capsules It resist to plasma bactericidal properties & phagocytosis . 17 4/11/2024 Kidney & Urinary System, Microbiology

18. Defense mechanism Several defenses help to prevent infection The urine itself: slightly acidic pH The flushing action of urine flowing out of the system Urine flow also promotes shedding of the epithelial cells lining the urinary tract. So, hundreds of thousands of epithelial cells are lost! Of course, any microorganisms attached to them are also shed. 4/11/2024 18

19. Defense mechanism ... In female, natural defenses of the urinary tract change over the course of a life. Vagina is lined with mucous membranes , It provides a barrier against foreign particles, captures them in its sticky mucus and clears them out It is nonspecific defense and has a main protective function during childhood and after menopause . 4/11/2024 19

20. Defense mechanism… During reproductive years, changes in the pH of the vagina. This is due to by production of estrogen hormone . This hormone causes the vaginal mucosa to secrete glycogen , which certain bacteria can ferment into acid, lowering the vaginal pH to approximately 4.5 . The pH shift that occurs during adolescence results in a significantly different normal flora in the vagina. These surfaces would have secretory IgA antibodies specific for any previously encountered infections. 4/11/2024 20

21. Normal flora of urinary tract The anterior urethra and vagina are the only anatomic areas of the urinary system permanently colonized with microbes. Commensal population of the urethra consists of a variety of organisms, with lactobacilli , streptococci , and coagulase-negative staphylococci NB . Lactobacillus plays an important role in the host defense mechanism against uropathogens (for female). 4/11/2024 21

22. Normal flora of urinary tract Neutral pH of vagina before puberty and after menopause , and the vagina harbors a flora like that of the urethra . When puberty begins, estrogen production causes glycogen release in the vagina, resulting in an acidic pH. Lactobacillus species grow well and contribute to an acidic environment by converting sugars to acid. Very common fungus Candida albicans is also present at low levels in the healthy female reproductive tract. 4/11/2024 22

23. Urinary tract infection(UTI) UTIs: result from invasion of the urinary system by bacteria or other microorganisms. Cystitis: bladder inflammation. Pyelonephritis: inflammation of kidney Prostatitis: inflammation of prostate gland Urethritis: inflammation of urethra 4/11/2024 23

24. Signs and symptoms Symptoms in UTI Definitions Urgency An unstoppable urge to urinate due to sudden involuntary contraction of the bladder muscles Frequency Urinating too often and at frequent intervals Dysuria Feeling of pain , discomfort or burning sensation while urinating Nocturia Frequently waking up at night to urinate because of UTI or bladder infection Urinary incontinence Loss of control of the bladder from a slight loss of urine following coughing, sneezing or laughing 4/11/2024 24

25. Urethritis It is inflammation of the urethra Urethritis is a bacterial or viral infection that causes swelling and irritation of the urethra . It’s also commonly caused by a STIs . Symptoms include painful, burning or frequent urination or a discharge from the urethra. 4/11/2024 25

26. Cystitis Cystitis is  inflammation of the bladder The symptoms of cystitis are dysuria (painful urination), frequency (frequent voiding), and urgency (an imperative “call to toilet”). These findings are like those of urethritis caused by STIs . However, STIs distinguished from urethritis by a More acute onset and severe symptoms, Pain during intercourse Genital blisters, sores, or rashes 4/11/2024 26

27. Cystitis… The urine is often cloudy and smelly . Cystitis patients also experience pain and tenderness in the suprapubic area. Fever and systemic manifestations of illness are usually absent. 4/11/2024 27

28. Pyelonephritis Inflammation of the kidney due to a bacterial infection . The typical presentation of upper urinary infection consists of flank pain and fever that exceeds 38.3°C. Systemic manifestations of illness occurs: Rigors, vomiting, diarrhea, and tachycardia These findings may be preceded of cystitis. It is estimated that 20 to 50% of pregnant women with acute pyelonephritis have premature babies , which is one of the most serious consequences of UTI. 4/11/2024 28

29. Prostatitis Prostatitis is inflammation of the prostate gland . Infection of the prostate is typically manifested as pain in the lower back, perirectal area, and testicles. In acute infection, the pain may be severe and accompanied by high fever, chills, and the signs and symptoms of cystitis. Inflammatory swelling can lead to obstruction of the neighboring urethra and urinary retention 4/11/2024 29

30. Types of UTI 1. Based on anatomical region involved it is classified as: Lower UTI Upper UTI Syndromes Cystitis and urethritis Pyelonephritis Signs and symptoms Local manifestation : dysuria, urgency, frequency Systemic manifestations : Fever, vomiting, abdominal pain Route of spread Ascending route Both ascending and descending Occurrence More common Less common 4/11/2024 30

31. 2. Based on symptoms of infection : classified as Asymptomatic UTI : is the presence of significant bacteriuria without signs or symptoms of a urinary tract infection Such asymptomatic bacteriuria, untreated, may lead to symptomatic infection, especially in pregnancy. Symptomatic UTI: is the presence of significant bacteriuria with signs or symptoms 4/11/2024 31

32. 3. Based on complexity of infection : classified as Uncomplicated UTI : typically affect people who are generally healthy and do not have any structural or neurological problems of the urinary system. Complicated UTI : UTIs associated with factors that compromise the urinary tract or host defense such as: Urinary obstruction, Urinary retention Immunosuppression Renal transplantation Pregnancy Kidney stone Catheters 4/11/2024 32

33. Common Etiologies of UTI Bacterial etiologies Gram Negative Rods E. coli (UPEC) Proteus mirabilis Klebsiella Enterobacter Serratia Pseudomonas STI pathogens N. gonorrhoeae Chlamydiae Gram Positive Cocci S. saprophyticus S. epidermidis S. aureus Enterococcus Spp. Corynebacteria 33 4/11/2024 Kidney & Urinary System, Microbiology

34. Viral etiology of UTIs Mumps virus CMV Coxsackie viruses HSV Adenoviruses (type 11) Other causes of UTI Candida Trichomonas vaginalis Schistosoma haematobium Microfilaria's 34 4/11/2024 Kidney & Urinary System, Microbiology

35. Etiological agents Escherichia coli Named after Esherich who first discovered the colon bacillus E. coli, is a gram-negative , facultative anaerobic, l actose-fermenting, rod-shaped Commonly found in the lower inte stine as a normal flora of human and warm-blooded organisms . Can be pathogenic both within and outside of the GI tract 4/11/2024 35

36. Virulence factors E. coli Uropathogenic E. coli (UPEC) cause UTI due to: Hemolysin , which is cytotoxic and facilitates tissue invasion Pili-mediated adherence to uroepithelial cells. The P pili-positive E.coli are generally uropathogenic The P pilli positive E.coli bind to digalactoside receptor of uroepithelial cells In addition, type 1 pili are essential for attachment to urinary epithelium in the urinary bladder 4/11/2024 36

37. Virulence factors E. coli … Bacterial cell surface virulence factor also include flagellum, capsular lipopolysaccharide and outer membrane proteins. The E.coli serotypes commonly responsible for community-acquired UTI are those normally found in the gut of the person, groups O1, 2, 4, 6, 7, and 75. These virulence factors are important in enabling the bacteria to colonize the urinary tract 4/11/2024 37

38. Klebsiella pneumoniae Klebsiella pneumoniae is a Gram-negative , non-motile, encapsulated, lactose-fermenting, facultative anaerobic, rod-shaped bacterium They are common, especially in long stay hospital patients and infection is often associated with urethral catheterization Possess polysaccharide capsule and fimbriae as a virulence factors 4/11/2024 38

39. Proteus Proteus mirabilis is a Gram-negative , facultatively anaerobic, non lactose-fermenting, and rod-shaped bacterium . P. mirabilis : primarily produces infections of the urinary tract It is highly urease positive , which splits urea into carbon dioxide and ammonia . This process raises the urine pH , precipitating magnesium and calcium in the form of struvite and apatite crystals, respectively . This results in the formation of renal (kidney) stones . The increased alkalinity of the urine is also toxic to the uroepithelium. 4/11/2024 39

40. Gram positive The major gram-positive bacteria in UTI cases are  Staphylococcus species, Enterococcus faecalis, Streptococcus agalactiae. Staphylococci aureus : are uncommon in routin e urinary tract infections, though they do cause infection in association with local instrumentation, implants , and diabetes. Urinary isolates of staphylococci are to be considered significant even with low colony counts , as they may be related to bacteremia 4/11/2024 40

41. S. saprophyticus General properties Gram-positive cocci arranged in grape like clusters Non – Motile, non – spore-forming Produce catalase 4/11/2024 41

42. S. saprophyticus … It is a 2 nd most common cause of UTI Over 40% of all young, sexually active women contain  S. saprophyticus  as part of their normal genitourinary flora It is also infrequently found as an asymptomatic colonizer of the urinary tract. Infected women usually have dysuria, pyuria , and bacteriuria. Patients respond rapidly to antibiotics and reinfection is uncommon. 4/11/2024 42

43. Enterococcus faecalis As their name implies, enterococci are enteric bacteria. The enterococci are gram-positive cocci , typically arranged in pairs and short chains E. faecalis is found in the large intestine in high concentrations and in the genitourinary tract . 4/11/2024 43

44. Enterococcus faecalis … Significant risk factors for enterococcal infections include use of catheters , prolonged hospitalization, and use of broad-spectrum antibiotics , particularly antibiotics that are inherently inactive against enterococci Virulence is mediated by an organism's capacity to build biofilms on host surfaces and by its resistance to antibiotics . Patients at higher risk include those receiving long-term hospital care and broad-spectrum antibiotics (particularly cephalosporins, to which enterococci are naturally resistant) 4/11/2024 44

45. Corynebacterium urealyticum Although it is a rare isolate in healthy individuals, the species represents a significant pathogen of the urinary system. As the name suggests, the strong urease producer C. urealyticum can produce enough urease to make the urine alkaline , which can cause the development of kidney stones. Immunosuppression , underlying genitourinary diseases, a prior urologic surgery, and prior antibiotic therapy are risk factors for C. urealyticum infections. 4/11/2024 45

46. Streptococcus agalactiae The genus gram-positive cocci Streptococcus typically arranged in pairs or chains Group B streptococci colonize the lower gastrointestinal and the genitourinary tract . Transient vaginal carriage has been observed in 10% to 30% of pregnant women Approximately 60% of women who are colonized with GBS will transmit the bacteria to their newborns. 4/11/2024 46

47. Streptococcus agalactiae When the mother is colonized with many bacteria, the likelihood of colonization at birth increases. Transmission occurs from an infected mother to her infant at birth S. agalactiae is are a leading cause of septicemia and meningitis in newborns. To prevent neonatal disease, it is recommended that all pregnant women should be screened for colonization with group B streptococci at 35 to 37 weeks of gestation 4/11/2024 47

48. Reading assignment Leptospirosis Acute post-streptococcal glomerulonephritis 4/11/2024 48

49. Predisposing factors Age . Sex: Sexually active females are more prone to UTI. Structural and functional abnormality of the urinary tract: Obstruction due to urethral stricture, calculus, enlarged prostate and genital prolapse Uncircumcision (for male). Sexual intercourse (multiple sexual partners): Increased sexual activity leads to more frequent UTI in women 4/11/2024 49

50. Predisposing… Wiping from back to front (especially for females) Infrequent and incomplete voiding Pregnancy : Anatomical and hormonal changes in pregnancy Metabolic: Diabetes mellitus Intervention: Instrumentation including catheterization and surgical procedure. Bacterial virulence: Pili and adherence to uroepithelium Vesicoureteral reflux (VUR) 4/11/2024 50

51. Prevention of UTI Keep personal hygiene. Stay well hydrated Urinate after sexual activity. Teach girls to wipe front to back. Medications An estrogen vaginal cream may help increase resistance to bladder infections Take any prescribed medication exactly according to the physician’s advice Follow aseptic procedure in catheterization 4/11/2024 51