Lecture 1 Urinary Tract Infections

Urogenital System Microbiology… Lectures 1 Urinary tract infections First: Urinary tract infections (UTIs) types : I. Upper UTIs: - Nephritis - Pyelonephritis: ➢ Inflammation of the renal Parenchyma ➢ Causes: 1. E. coli is most common cause 2. Proceeded by cystitis (urinary bladder inflammation) then Bacteria migrate up (via ureter to kidney) 3. may spread also via blood stream (causing septic shock) ➢ Clinical picture: 1. Flank pain 2. fever (> 38.5 C) 3. Rigor, vomiting, diarrhea, and tachycardia 4. Tenderness over the costo-vertebral angle - Ureteritis: ➢ Inflammation of ureter (one or both) ➢ Infection is up from the bladder or Down from the kidneys II. Lower UTIs - Cystitis: ➢ Inflammation of the urinary bladder, it’s the Most common UTI ➢ Causes: 1. E. coli is most common cause 2. Other microbes can also cause cystitis: ▪ Gram Negative: Klebsiella, Proteus, Enterobacter ,Pseudomonas ▪ Gram positive: Staph. Saprophyticus, Staph. Epidermidis, Enterococcus ▪ Candida albicans, rare, in Immunocompromised ➢ Clinical picture 1. Symptoms: ▪ Dysuria (painful urination) ▪ Frequency (frequent voiding) ▪ Urgency (cannot stand even for few seconds “call to toilet”) 2. To differentiate between urethritis & cystitis, cystitis shows: ▪ More acute onset & More severe symptoms ▪ Bacteria in urine make it cloudy with malodorous (bad odor) ▪ Hematuria (50%) ▪ Suprapubic pain and tenderness ▪ No fever or general symptoms - Urethritis: ➢ Inflammation of the urethra ➢ Causes: 1. Chlamydia trachomatis: Most common cause 2. Others: Neisseria gonorrhea, Ureaplasma, or Mycoplasma 3. Cases that not caused by Neisseria called “Non-specific Urethritis” or “ Non-gonococcal urethritis” ➢ Clinical picture: Dysuria, urethral discharge or both occur - Prostatitis: ➢ Inflammation of the prostate ➢ Most are not infectious disease (m.o hidden inside the prostate..) ➢ If it was caused by pathogens, the most common: 1. Bacterium the main (Same bacteria as in cystitis/pyelonephritis) 2. Virus, Fungus & Protozoan ➢ Clinical picture: 1. Pain at Lower back, perirectal area & testicles. 2. Fever, chills + signs/symptoms of cystitis 3. Leads to urethral obstruction (it surrounds the urethr) as a result urinary Retention 4. On Rectal palpation (PR) test : Prostate is boggy and tender _ second: general features of UTI: - More Common in females (have shorter urethra) - E. coli contaminates perineal and urethral Areas (reservoir of UTI), but less than 10 serotypes account for majority of UTI - 95% of UTI caused by G- rods, 90% of them Caused by E. coli _ third : sources of UTIs: - Hospitalized patients UTI: Pseudomonas and Enterococci (G+ cocci) - Young active women: Staph. Saprophyticus - Catheterized patients: Candida albicans (specially if taking antibacterial therapy, or DM; and usually is symptomless) _ fourth : urinary culture: - Instruction in specimen collection: urine is sterile normally, but Voided urine is contaminated with urethral Flora; and in females by perineal and Vaginal flora - Contamination diminished by: 1. Cleaning periurethral area before voiding 2. Flash out initial part of urine “Clean-Voided Midstream Urine”, 3. Collection via a catheter 4. Suprapubic aspiration (mainly used in Children, and is normally sterile) - Quantitative bacteriology: The Gold standard for the detection of UTI (Bacteria/ml): 1. Bet 100 to 1000 , No infection 2. < 105 /ml, Cystitis 3. > 105 /ml, Pyelonephritis KEEP this NEGATIVE mnemonic : klebsiella, E.coli, Enterobacter & Proteus. (All gram –) _ First: E.coli I. II. III. General features: - Gram-negative bacilli - Pink colonies on MacConkey’s Agar , mean s they’re Lactose-Fermenter - IMViC: ++ -- (indole +, methyl red +, Voges-Proskauer – , citrate utilization – ) - E.coli that infect urinary tract called Uropathogenic “UPEC” Pathogenesis: - Exotoxins: 1. Alpha-Hemolysin: Pore-forming cytotoxin 2. Cytotoxic necrotizing factor (CNF): A-B Toxin, disrupts G proteins (signaling) 3. Shiga toxin (Stx): Produced by E. coli as Well as Shigella, A-B toxin; A-part blocks protein synthesis, B responsible for binding of the toxin to the host cell 4. Enterotoxin: Heat stable (ST) & heat labile (LT) Pilli: 1. Type I pili : binds to mannose moiety at periurethral and Perineal areas . On/Off = swimming movement / Adherent phases. 2. Type P pilli : for bladder and kidney Attachment (colonization) Have receptors called Gal-Gal in renal pelvis (kidney) & bladder, making the Bacteria able to cause pyelonephritis P Pilli is positive/ exist in : < 20% of E. coli strains in general.. & in >70% of E. coli causing pyelonephritis - Minor trauma or mechanical disruption admits E.coli to bladder - Motility by flagellar motors Treatment: - Often empirically (needs susceptibility test) - Resistant commonly to ampicillin, So use (before susceptibility test results): Co-trimoxazole, or fluoroquinolones - Then modify according to susceptibility test _ second: Klebsiella: I. General features: - Gram negative, Lactose-Fermenter bacilli (Klebsiella. pneumoniae: most common spp.) - Has polysaccharide capsule, making it 1. Serotyping: there are 70 capsular types 2. non-motile 3. Ag cross reacts with S. pneumoniae, And H. influenzae 4. Interferes with complement activation & phagocytosis - Colonies: appears Pink on MacConkey’s (LF) agar, Mucoid, and glistening - IMViC: - - + + ( opposite E.coli) II. Treatment: - Commonly resistant to many anti-microbial Agents; so use: 1. Combinations: e.g. Ampicillin/Sulbactam Piperacillin/Tazobactam 2. New Cephalosporines; Fluoroquinolones: e.g. Cefepime, Levo- & Gati-floxacin _ third: Enterobacter: I. General features: - Gram negative - rapid Lactose-Fermenter - motile bacilli (family Enterobacteriaceae) - Less virulent than Klebsiella - Detected in mixed infections II. Treatment: - Resistant to: Ampicillin, first generation Cephalosporines - Sensitive to : Later generation Cephalosporines - But Mutants Produce Beta-lactamases, so Become resistant to Cephalosporines _ Fourth: Proteus: - Gram negative, non-lactose fermenter Very Motile bacilli , and that makes Swarming phenomena During growth, produce Bad fishy odor P. mirabilis: Most common spp. (Indol –ve) P. vulgaris: Less common spp. (Indol +ve) Potent Urease producer (Urease converts urea into ammonia, which cause alkalization of the urine, as a result stone formation and Ammoniac odor of urine) - Treatment: 1. Some Sensitive to Penicillins 2. some Others Resistant to Ampicillin and Cephalosporines Past years’ questions _ One of the following is not true : Answer: pyelonephritis detection less than 10 ^5 _ Case with flank pain , fever , tenderness over costal vertebral angle, The disease and m.o that can cause these symptoms : Answer: pyelonephritis __ E.coli _ Ecoli and klebsiella differ in all of the following except: Answer: lactose fermentation