Urinary Tract Infection (UTI) PDF

Urinary Tract Infection (UTI) Definition: infection of the urinary tract indicated by presence of > 10 pus cells/HPF in centrifuged urine sample (pyuria). Sterile pyuria: presence of pus cells without organisms. It occurs in some conditions e.g. renal TB, analgesic nephropathy, and bladder tumors. B...

Urinary Tract Infection (UTI) Definition: infection of the urinary tract indicated by presence of > 10 pus cells/HPF in centrifuged urine sample (pyuria). Sterile pyuria: presence of pus cells without organisms. It occurs in some conditions e.g. renal TB, analgesic nephropathy, and bladder tumors. Bacteriuria: urine culture proves presence of bacteria in urine with or without symptoms of UTI. Predisposing factors Females > males due to short urethra - Children > adults due to bad hygiene. Immunosuppression e.g. in cases of diabetes mellitus. Presence of obstruction to urine flow e.g. congenital abnormalities, urethral strictures, and stones. Causative organisms E-coli is the most common organism (80%) in uncomplicated infection. Staphylococcus saprophyticus (10%). Other Gram-negative bacilli e.g. Proteus, Pseudemonus & Klebsiella are the commonest organisms. in complicated infection. Clinical picture kidney/ureter Upper UTI (pyelonephritis): inflammation of the renal tissue or pelvis. Manifestations: loin pain, chills, & fever. Lower UTI (cystitis): inflammation of the bladder & urethra. Manifestations: dysuria (burning micturition), urgency & frequency of urination. Uncomplicated (simple( UTI: occurs for the 1st time without complications. It is usually lower UTI. Complicated (recurrent) UTI: usually upper UTI with complications e.g. renal stones or anatomical dysfunction. Management of UTI Specific treatment: Antimicrobial drugs: In lower UTI (usually simple): The antimicrobial drug should be excreted in large amount in urine. Drugs used routinely: co-trimoxazole, amoxycillin or nitrofurantoin. Duration of treatment: 3-5 days. In some cases, simple UTI could be treated by single large dose of fosfomycin (3g oral once) but with lower cure rates. In upper UTL (usually recurrent): The antimicrobial drug should be bactericidal of high tissue penetration e.g. aminoglycosides, fluorinated quinolones or 3ª gen cephalosporins.  Duration of treatment: 10-14 days followed by chemoprophylaxis for 15-30 days to prevent recurrence. Indications of chemoprophylaxis: recurrent upper UTI and UTI in pregnancy and children. Drugs used routinely in chemo-prophylaxis: co-trimoxazole, amoxycillin or nitrofurantoin. 2. Changing the urinary pH Normal urine pH is 5.2-6.5. It is possible, by use pharmacological agents, to produce urinary pH values ranging from ~ 5.0 to 8.5. Drug Alkalinization of the urine: Indications: To enhance the activity of sulfonamides & aminoglycosides. To prevent uric acid stones and sulfonamides crystalluria. To relieve dysuria (burning micturition) in some cases of bladder infection. E. coli is inhibited in alkaline medium. Alkalinizing agents: Oral: sodium and potassium citrate salts: citrate is metabolized into bicarbonate which is excreted in urine. Intravenous bicarbonate solution: contains 5% NaHCO3. Acidification of the urine: Indications: To enhance the activity of nitrofurantoin, fosfomycin, and hexamine. Acidifying agents can lead to dangerous systemic acidosis in cases of renal or hepatic impairment. Acidifying agents: Oral: ascorbic acid > 2 g/d. Intravenous ammonium chloride (NH4Cl) solution. 3. Urinary antiseptics: no tissue enter, just clearing among urin pathway Hexamine (Methenamine) In acidic urine, hexamine is hydrolyzed into ammonia and formaldehyde. Formaldehyde is bactericidal and lacks bacterial resistance. Urine must be acidified (pH below 5.5) to get this effect. Side effects: Chemical cystitis. Nitrofurantoin Nitrofurantoin causes bacterial DNA damage by an unclear mechanism. It is used only as a urinary antiseptic in lower simple UTI against E. coli. Other urinary tract Gram-negative bacteria are often resistant. It becomes more active in acidic urine. It is contraindicated in renal failure.  Adverse effects include hemolytic anemia in patients with G-6-PD deficiency, peripheral neuritis, and dark brown urine. Fosfomycin Fosfomycin inhibits bacterial cell wall synthesis. It is a broad spectrum antibiotic against many Gram positive and negative spp. It is used only as a urinary antiseptic in lower simple UTI. It becomes more active in acidic urine. Causes of failure of treatment: Improper choice, dose, or duration of drug treatment. Bacterial resistance. Presence of complications e.g. renal calculi, ureteric stricture, etc. Renal failure. Immunocompromized patient: e.g. DM UTI with Renal Failure Penicillin Most cephalosporins Co-trimoxazole UTI in Pregnancy and lactation Penicillin Most cephalosporins