UTI Flashcards

1
Q

List risk factors of UTI

A
  1. More common in women & girls bec their urethras are short and closer to rectum which make it easier for bacteria to enter urinary tract
  2. A previous UTI
  3. Sexual activity (Honey moon cystitis)
  4. Charges in vaginal flora by menopause or spermicides
  5. Pregnancy
  6. Structural problems in urinary tract such as prostate enlargement
  7. Poor hygeine
  8. Catheterization (hospital-acquired UTI)
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2
Q

…….is the most common cause of UTI in anatomically non-obstructed normal UT (….%)

A

E. coli
90

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3
Q

What is the source of reaction with E.coli

A

Microbial flora
Strains often originate from patient’s owan fecal flora
The bacteria colonise the peri-urethral area then ascend to UT

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4
Q

Mention virulence factors of E.coli

A
  1. P fimbriae (Pili) bind to specific receptors on the UT epithelium, they are also called pyelonephritis associated pili (PAPs)
  2. Motility: facilitate its ability to ascend into bladder & kidney
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5
Q

Mention biochemical for E.coli identification

A
  1. Oxidase, urease, citrate, H2S -ve
  2. Indole +ve
  3. Fermentation of 3S on TSI + gas
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6
Q

The strain K.pneumoniae most commonly encountered in UTI is…….

A

Aerogenes

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7
Q

Mention infections caused by Klebsiella

A

Hospital acquired UTI, RTI, SSI

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8
Q

Klebsiella oxytoca is differentiated from pneumoniae in being……

A

Indole +ve

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9
Q

Mention virulence factors of Klebsiella

A

Antiphagocytic capsule
Pili: for adhesion & biofilm formation

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10
Q

On culture media Klebsiella produces…….., while Proteus produces

A

Large muscoid rose pink colonies on MacConkey’s agar
Swarming growth on nutrient agar & blood agar, pale-yellow colonies on MacConkey’s, Cystine lactose electrolyte deficient medium suppresses the swarming growth

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11
Q

Mention biochemical for Klebsiella identification

A

Oxidase, H2S, indole -ve
Urease & citrate +ve
Fermentation of 3S + gas

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12
Q

Compare proteus mirabilis & vulgaris

A

M: indole -ve, susceptible to ampicillin & cephalosporins
V: indole +ve, not susceptible to ampicillin & cephalosporins, affect immunosuppressed patients & those on prologned Ab therapy

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13
Q

List virulence factors of proteus

A
  1. Urease production, degrades urea to ammonia raising urine pH & this encourages stone formation which can obstruct urine flow & serve as nidus for recurrent infection
  2. Peritrichate flagella: motility, facilitates entry into bladder
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14
Q

Mention biochemical for Proteus identification

A
  1. Oxidase & citrate -ve
  2. h2S +ve & rapid urease production
  3. Ferment glucose only + gas production on TSI
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15
Q

Mention charachers of pseudomonas that distinguish it from enterobacteriacae

A
  1. They are obligate aerobes
  2. CHO non-fermenters but utilise glucose oxidatively
  3. Oxidase +ve
  4. Naturally resistant to many Abx
  5. Produce soluble diffsuible exopigment
  6. Motile with single polar flagellum
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16
Q

List virulence factors of peudomonas

A
  1. Pili: attach to mucus membrane & skin
  2. Endotoxin: fever, shock, oliguria, leukopenia, DIC
  3. Alginate & quoram sensing molecules allow biofilm formation & chronicity of infections
  4. Enzymes & toxins as proteases, elastases & hemolysins
  5. Exotoxins A which causes tissue necrosis by blocking protein synthesis
17
Q

Mention biochemical identification for Pseudomonas aeruginosa

A
  1. Oxidase, citrate, urease +ve
  2. It utilizes glucose with production of acid only
  3. Indole & H2S -ve
18
Q

Mention virulence factors of S.saprophyticus

A

Surface-associated protein & lipoteichoic acid: selective adherence to human urothelium

19
Q

Describe identification of S.saprophyticus

A
  1. Non-hemolytic colonies on blood agar, white colonies on nutient agar
  2. Gram +ve cocci arranged in grape-like irregular clusters
  3. Catalase +ve, coagulase -ve, novobiocin resistant
20
Q

Describe general morphologi of enterococci

A

Gram +ve, non motile, non spore formin cocci arranged in pairs

21
Q

Describe growth of enterococci on culture media

A
  1. Blood agar, small non-hemolytic colonies
  2. MacConkey’s, small rose pink colonies
  3. Bile esculin agar, black colonies
    6.5 NaCl & at 45degC
22
Q

Describe biochemical identification of Enterococci

A

Catalase -ve, rapid reduction bleaching of litmus milk

23
Q

UTI due to candida is associated with…….

A

Urinary catheters, pregnancy, Abx, immunosuppressive drug administration

24
Q

Describe culture media chchs of Candida albicans

A

Non hemolytic colonies on blood agar
Creamy white colonies on Sabouraud’s dextrose agar
Germ tube test: Candida albicans begins to form true hyphae after serum inoculation for e hrs at 37degC

25
Q

Diagnostic specimen of UTI is……
Mention its tests

A

Mid-stream urine or suprapubic aspiration
1. Examination of wet preparation for WBCs (more than 10 on HPF), RBCs, crystals, yeast, eggs
2. +ve nitrite or leukocyte esterase (dipstick tests)
3. Inoculation & ifentification of causative agent using caliberated loop culture on blood MacConkey’s, Sabouraud’s. Incubate aerobically for 24-48 hrs at 37 degC

26
Q

The presence of ………is indicative of significant bacteriuria

A

10^5 CFUs

27
Q

Sterile pyuria is caused by……

A

M.tuberculosis

28
Q

Empirical Abx for uncomplicated UTI is….., while that for complicated is……

A

Trimethoprim-sulfamethoxazole/nitrofurantoin
Fluoroquinolones (cipro/levo)

29
Q

Asyptomatic bacteriuria is treated in case of…….,….,…..

A

1.Pregnant women
2.Adults scheduled to have urinary tract procedures that could cause mucosal bleeding & translocation of bacteria into blood
3.Neutopenic parients

30
Q

Cause of Acute poststreptococcal glomerulonephritis

A

Typically occurs 2 to 3 wks after skin infection by certain group of A streptococcal types
The disease is intiated by Ag-Ab complexes on the glomerular BM (type III hypersensitivity)

31
Q

What is the laboratory diagnosis of acute poststreptococcal glomerulonephritis?

A

Titer of anti-DNase B are high in group A beta hemolytic streptococcal skin infections & the estimation of DNase Ab level is of greater value than ASOT in this case.

32
Q

Mention urinary tract infections caused by viruses

A
  1. Hemorrhagic cystitis after stem cell/solid organ transplant
  2. Nephritis following renal graft
33
Q

Describe pathogenesis if BK virus

A

Enters via RT, rarely causes clinical disease.
After infection it disseminates & establishes persistent infection in renal tissue throughout life. Immunosuppression may reactiavte the virus leading to hemorrhagic cystitis & nephritis. Might kead to graft rejection.