Urinary tract infections Flashcards
What are the symptoms of urethritis and cystitis?
Dysuria, frequency, urgency
What are symptoms of pyelonephritis?
Pain in the flanks, fever
How are UTIs diagnosed?
Symptoms and dipstick test
What kind of sample is required for UTI diagnosis?
Clean voided midstream urine
What does a dipstick test look for?
Leukocyte esterase and nitrite
What does a positive leukocyte esterase result indicate?
Pyuria (WBC in urine)
What is the gram stain for enterobacteriaceae?
Gram negative
What is the shape of enterobacteriaceae?
Rod
What is the oxidase test for enterobacteriaceae?
Oxidase negative
What is the catalase test for enterobacteriaceae?
Catalase positive
Serology for enterobacteriaceae is based on what antigens?
O-polysaccharide of LPS, K and H antigens
What are the virulence factors associated with enterobacteriaceae?
Endotoxin, capsule, T3SS, sequestration of growth factors, antigenic phase variation
What is responsible for the degree of virulence of different strains of E. coli?
Acquisition of plasmids, prophages, and pathogenicity islands
What is responsible for E.coli adherence to host mucosal surfaces?
Fimbriae or pili
What can differentiate E. coli from salmonella or shigella?
Most E. coli spp. ferment lactose
What is the most common gram negative rod isolated from patients with sepsis?
E. coli
What is the most common cause of UTIs?
E. coli
What is the reservoir in E. coli UTI?
Patient’s intestinal flora
What are the virulence factors of E. coli UTI?
Adhesins, hemolysin, endotoxin
What do most E. coli strains possess to aid in attachment to epithelial surfaces?
Type I pili
What is the type I pili?
Present on most E. coli strains - binds to mannose residues commonly present on epithelial surfaces
What is the P pili?
Expressed by some subpopulations of E. coli - binds sugar residues specifically on uroepithelial cells
E. coli strains that cause pyelohnephritis usually possess which type of pili?
P pili
What is the shape of staphylococcus?
Clusters
What is the shape of streptococcus?
Pairs or chains
What is the gram stain for staphylococcus?
Gram positive
What is the second leading cause of UTIs?
S. saprophyticus
How can S. saprophyticus be differentiated from other CoNS?
Novobiocin resistant
What are the common hospital acquired UTI pathogens?
Proteus, pseudomonas, enterococcus
What is the gram stain for proteus?
Gram negative
What is the prevalence of proteus for UTI isolates in chronically catheterized patients?
20-45%
How does proteus cause kidney stones?
- Produces urease 2. Urease hydrolyzes urea to ammonia - alkalizes urine 3. Alkalinization leads to precipitation of organic and inorganic compounds - kidney stones
Does proteus produce biofilms?
Yes
What is the treatment for proteus?
TMP-SMX
What is the gram stain for pseudomonas?
Gram negative
What is the shape of pseudomonas?
Motile rod
What is the oxidase test for pseudomonas?
Oxidase positive
How can pseudomonas be differentiated from enterobactericeae?
Oxidase test
Which bacteria produce a blue-green pigment?
Pseudomonas aeruginosa
Pseudomonas aeruginosa is typically seen in what patient profile?
- Long term indwelling catheters 2. Obstruction of GU system or urinary tract instrumentation / surgery 3. Multiple courses of abx
Enterococcus are what group of streptococci?
Group D streptococci
What is the gram stain for enterococcus?
Gram positive
What is the catalase test for enterococcus?
Catalase negative
How can enterococcus be differentiated from S. pneumoniae?
- Tolerates high salt and bile 2. Not sensitive to optochin
What are the risk factors for enterococcus?
- Prolonged hospitalization 2. BSA
What are the clinical diseases associated with enterococcus?
UTI, peritonitis, endocarditis
What is the diagnosis for asymptomatic bacteriuria?
Significant bacteriuria on two successive urine cultures in women or from a single culture in men from catheterized urine specimen
When is treatment for asymptomatic bacteriuria indicated?
- Pregnant women 2. Prior to urologic surgery 3. After renal transplantation
What is the treatment for uncomplicated cystitis?
Trimethoprim / sulfamethoxazole
What is the treatment for pyelonephritis?
Aggressive - fluoroquinolones for gram negatives, amoxicillin for gram positives
What is the treatment for asymptomatic bacteriuria?
Cephalexin, nitrofurantoin