Term
| what are examples of upper urinary tract infection? |
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Definition
| acute pyelonephritis (kidney), intrarenal/perinephric abscesses, prostatitis, and systemic |
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Term
| what are examples of lower urinary tract infection? |
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Definition
| urethritis, cystitis (bladder and urethra), and superficial (mucosa - nothing systemic) |
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Term
| what is the definition of a urinary tract infection? |
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Definition
| UTI: whenever microorganisms are detected in urine or any part of the urinary tract - including the prostate gland (*UT = normally devoid of flora). usually detectable @ ~ 10^2-10^5 CFU/in urine sample. |
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Term
| how many pathogens are UTIs generally due to? |
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Definition
| usually a single pathogen unless in institutionalized pts w/obstruction or catheters (complicated UTIs) |
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Term
| what is a recurrent UTI? what are the 2 types of recurrent UTIs? |
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Definition
| an infection that recurs after antibx tx, which can either be a *relapse: same strain of bacteria, usually involving an unresolved kidney/prostate infection or rapid re-infection due to vaginal/intestinal colonization (infection was never totally cleared) or a *re-infection: UTI due to a different bacteria or re-introduction of a previous isolate (but there was a time where the infection had been cleared completely). |
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Term
| what are the major symptoms associated with urethritis? |
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Definition
| dysuria, frequency, and urgency. no bacteria. usually if this is in males, it is an STD (as opposed to a UTI). |
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Term
| what are the major symptoms associated with cystitis? |
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Definition
| dysuria, frequency, urgency, suprapubic pain, bacteriuria, hematuria, and pyuria |
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Term
| what are the major symptoms associated with pyelonephritis? |
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Definition
| dysuria, frequency, urgency, suprapubic pain, flank pain, fever/chills, bacteriuria, hematuria, and pyuria (+ casts) |
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Term
| what are the major symptoms associated with prostatitis? |
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Definition
| dysuria, +/- frequency, +/- urgency, suprapubic pain, lower back pain, fever/chills (in severe forms), bacteriuria, +/- hematuria, and pyuria |
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Term
| how are acute UTIs categorized? |
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Definition
| community-aquired (non-catheter) or HCA (catheter-associated). either may be symptomatic or not |
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Term
| who is usually affected most by UTIs? |
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Definition
| young women, particularly after sexual activity. unusual in males between 1-50. |
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Term
| what % of nosocomial infections are UTI? |
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Definition
| 40-45% - almost all associated with instrumentation/catheterization |
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Term
| what are the top bacteria responsible for community acquired UTIs? |
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Definition
| e. coli (80%), followed by s. saprophyticus (5-15% young sexually active women), klebsiella pneumoniae/proteus mirabilis (~5%), and enterococci (very rare). (these kinds of infections usually are associated with normal flora) |
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Term
| what are the top bacteria responsible for nosocomial UTIs? |
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Definition
| e. coli (50%), proteus mirabilis (bug everyone forgets about for UTIs), klebsiella pneumoniae, pseudomonas aeruginosa, serratia marcescens, enterobacter, enterococci, s. epidermis, s. aureus, corynebacterium urealyticum, and acinetobacter baumannii. (many of these are antibx-resistant) |
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Term
| what are some unusual UTI-causing pathogens? |
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Definition
| ureaplasma urealyticum, mycoplasma genitalium, and m. hominus (roles not completely defined). adenovirus can cause hemorrhagic cystitis in children/young adults. candida albicans (commonly causes UTIs in catheterized ICU pts). m. tuberculosis (should be consistent with clinical setting - do cx, check for pyuria, acidic urine and abnormalities in UT) |
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Term
| what is the etiology of urethritis (no bladder/renal involvement)? |
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Definition
| urinary symptoms, pyuria, but *sterile urine. usually an STD, consider n. gonorrhoeae, c. trachomatis, and HSV |
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Term
| what is the normal pathogenesis of a UTI? |
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Definition
| usually an ascending infection, the initial step of a UTI is (in women), colonization of the vaginal introitus, periurethral skin, and distal urethra w/enteric gram negative bacteria (usually endogenous). colonization is facilitated by alteration of the vaginal flora due to antibx, genital infections, contraceptives (spermacide), and menopause. |
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Term
| what does development of a UTI depend on? what does normal clearance/killing of bacteria depend on? |
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Definition
| the strain of bacteria (virulence), inoculum size, and host defenses. normal clearance/killing of bacteria is due to flow/dilution effect of urine, high urea/osmolarity/low pH, and presence of an acute inflammatory response. |
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Term
| how can a UTI start from hematogenous spread? |
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Definition
| this usually occurs with debilitated pts (chronically ill/immunosuppressed), where bacteremia w/s. aureus or candida infect the kidney. therefore if s. aureus is found in the urine, bacteremia and endocarditis need to be evaluated. |
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Term
| what conditions affect UTI pathogenesis? |
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Definition
| sexually active younger females are at higher risk due to shorter urethra and closer proximity to the anus. spermicide and menopause will also increase risk in these women. catheterization/instrumentation, neurogenic bladder, vesico-ureteral reflux, calculi, pregnancy and enlarged prostate also all increase UTI risk. DM pts or pregnant women both also have urine more suitable for UTIs. |
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Term
| what are some genetic circumstances which predispose pts to easier UTI occurrence? |
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Definition
| a difference in the # and concentration of receptors on cells that bind fimbriae as well as mutations in host immune system genes. |
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Term
| what are bacterial virulence factors increasing their ability to cause UTIs? |
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Definition
| pili/fimbriae, aerobactin (siderophore - iron acquiring), hemolysin, cytotoxins, serum resistance, *urease (breaks down urea to CO2, H2O, and NH3, increasing pH, calculi formation and bacterial growth), flagella (mobile against urine flow), endotoxin (decreases ureteral peristalsis - can also lead to fever/sepsis), growth factor synthesis, capsule (anti-phagocytic), and biofilm formation (esp on catheter) |
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Term
| what is the most common source of gram negative bacteremia in hospitalized pts? how many are symptomatic? what is the most important risk factor? that is the source? |
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Definition
| catheter-associated UTIs, 10% of which are symptomatic. the most important risk factor for these is length of catheterization. source: bowel, personnel hands, solutions, and instruments. these infecting strains are usually more antibiotic resistant than community-acquired. |
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Term
| what is an encrusted catheter? |
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Definition
| a catheter w/a biofilm which protects pathogens from antimicrobials/phagocytosis. the organism in the biofilm may not however be causing the UTI - therefore the urine sample needs to not be contaminated by this. |
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Term
| what is UTI tx tailored to? |
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Definition
| host, nature/site of infection, and local patterns of antimicrobial susceptibility |
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Term
| what is a "complicated UTI"? |
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Definition
| complicated UTIs are associated with underlying conditions that increase the risk of failing therapy, such as: obstruction, urologic dysfunction, pregnancy, DM, immune suppression, and/or multi-drug resistant uro-pathogen. often HCA UTIs are complicated and recurrent infections caused by the same organism are classified as complicated as well. |
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Term
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Definition
| *establish pyuria: urine leukocyte esterase test or >8 WBCs/mm^3 in a wet mount of spun urine. *establish bacteriuria: gram stain of urine or urine nitrite test (determine if nitrate has been reduced to nitrite, though s. saprophyticus/enterococcus cannot do this) |
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Term
| in cases of relapsing UTIs in catheterized pts or those with pyelonephritis (complicated infections), what other diagnostics need to be performed? |
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Definition
| cx and antibx sensitivity testing to ensure successful eradtication |
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Term
| what is the most common agent responsible for all UTIs? |
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Definition
| escherichia coli, the predominate species of gram negative, facultative anaerobes found in the colonic flora |
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Term
| what virulence factors are possessed by e. coli? |
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Definition
| type 1 fimbriae (cystitis), P fimbria (pyelonephritis), hemolysins, aerobactin (siderophore), resistance to serum killing, and synthesis of growth factors (guanine, arginine) |
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Term
| what will a urine dipstick positive for e. coli show? |
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Definition
| (+) nitrites, (+) gram negative rod, (+) lactose, (+) indole, and (-) oxidase |
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Term
| what characterizes proteus mirabilis as a UTI-causing pathogen? |
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Definition
| proteus mirabilis is found in the GI tract of mammals, and the urinary tract is its most common site of infection. it is a common source of UTIs in pts w/long term catheters. **if urine pH is >7.9, definitely check for proteus and calculi.** it is a gram (-) rod, lactose (-), indole (-), H2S (-), and oxidase (-). it has a very powerful urease and swarming mobility flagella) |
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Term
| what virulence factors are associated with proteus mirabilis? |
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Definition
| pili, biofilms on catheters, IgA protease, **flagella**, **powerful urease** (allows pH to be raised, easier formation of renal calculi, and catheter obstruction) |
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Term
| what are the providencia and morganella spp? |
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Definition
| enteric gram (-) rods *similiar to proteus, but rare in immunocompetent pts. generally only seen in long term catheter pts, providencia and morganella should be cultured for w/alkaline urine (produces urease). providencia and morganella are both highly resistant to antibx. |
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Term
| how can providencia and morganella be diagnosed? |
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Definition
| urease (+), indole (+), and H2S (+) |
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Term
| what characterizes klebsiella pneumoniae as a UTI-causing pathogen? |
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Definition
| klebsiella pneumoniae is found in the GI tract of humans and is isolated more from pts w/calculi. klebsiella pneumoniae can contribute to calculi retention b/c of *extracellular polysaccharide production*. klebsiella is also resistant to antibx and produces *copius capsule. urease (+), lactose (+), and indole (-). |
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Term
| what is important about enterobacter cloacae/aerogenes infections? |
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Definition
| these are prominent nosocomial pathogens b/c of **significant resistance to antibx**. source: hospital equipment/food. particularly related to catheter UTIs. risk factors: co-morbid disease, antibx tx, ICU tx. lactose (+), indole (-) |
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Term
| what characterizes serratia marcescens as a UTI-causing organism? |
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Definition
| rarely colonized healthy pts. serratia marcenscens is found in moist environments (food, blood products, IV solution, milk, lotions, and disinfectants), serratia is antibx resistant - but still susceptibile to gram negative appropriate antibx. *some strains produce a red pigment* lactose (-), indole (-) |
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Term
| what characterizes pseudomonas aeruginosa as a UTI-causing organism? |
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Definition
| pseudomonas aeruginosa is *ubiquitous in the health-care environment and often causes UTIs as a *complication of foreign body in the UT. if isolated, consider it a *complicated UTI (test sensitivity, treat longer, remove obstruction to prevent relapse). gram (-), motile, oxidase (+), urease (+), lactose (-), and capsule producing |
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Term
| what characterizes coagulase (-) staph saprophyticus as a UTI-causing organism? |
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Definition
| s. saprophyticus is spread through sex or contact w/animals and is associated with 5-15% of community acquired UTIs in *newly sexually active women (honeymoon cystitis). staph saprophyticus creates *adhesins that bind urothelial cells and produces *urease (kidney/uretal stones). staph saprophyticus is *always nitrate negative on urine dipsticks*, is novobiocin resistant, and is sensitive to antibx |
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Term
| what characterizes coagulase (-) staph epidermidis as a UTI-causing organism? |
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Definition
| staph epidermidis is the most abundant species on the skin, nasopharynx and vagina. it is a common cause of catheter-associated UTIs and forms a protective biofilm on devices (catheters). it is novobiocin sensitive, and antibx resistance is a problem. |
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Term
| even though it is not a common cause of UTIs, what needs to be considered in terms of UTIs due to staph aureus? |
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Definition
| bacteremia and endocarditis need to be tested for. antibx resistance is also a concern (MRSA). |
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Term
| what characterizes enterococcus faecium/faecalis as UTI-causing organisms? |
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Definition
| these normal GI flora are usually nosocomial pathogens, esp in those treated w/broad spectrum antibx. enterococcus faecium/faecalis will often affect debilitated pts w/renal stones, UT instrumentation, or sx. endocarditis is a risk in pts w/preexisting heart damage. many of these UTIs are asymptomatic. enterococcus faecium/faecalis can be antibx resistant. gram (+), **catalase (-) |
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Term
| what characterizes corynebacterium urealyticum as a UTI-causing organism? |
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Definition
| corynebacterium urealyticm causes *alkaline-encrusted cystitis* (chronic bladder infection associated with deposition of ammonium mag phos on ulcerating lesions in the bladder). it has *high urease activity, leading to strong alkaline urine and antibx resistance is observed. |
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Term
| what characterizes candida albicans as a UTI-causing organism? |
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Definition
| candida albicans (part of mouth/gut flora) related UTIs are more of a risk for DM pts, or those catheterized, on broad spectrum antibx, and/or prior sx procedure. candida albicans is the *most common pathogen of nosocomial UTIs in ICU pts. most pts with this as a UTI are asymptomatic and unless complicated, tx is not indicated. |
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