UTI

Question 1

List risk factors of UTI

Answer 1

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)

Question 2

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

Answer 2

E. coli
90

Question 3

What is the source of reaction with E.coli

Answer 3

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

Question 4

Mention virulence factors of E.coli

Answer 4

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

Question 5

Mention biochemical for E.coli identification

Answer 5

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

Question 6

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

Answer 6

Aerogenes

Question 7

Mention infections caused by Klebsiella

Answer 7

Hospital acquired UTI, RTI, SSI

Question 8

Klebsiella oxytoca is differentiated from pneumoniae in being……

Answer 8

Indole +ve

Question 9

Mention virulence factors of Klebsiella

Answer 9

Antiphagocytic capsule
Pili: for adhesion & biofilm formation

Question 10

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

Answer 10

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

Question 11

Mention biochemical for Klebsiella identification

Answer 11

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

Question 12

Compare proteus mirabilis & vulgaris

Answer 12

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

Question 13

List virulence factors of proteus

Answer 13

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

Question 14

Mention biochemical for Proteus identification

Answer 14

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

Question 15

Mention charachers of pseudomonas that distinguish it from enterobacteriacae

Answer 15

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

Question 16

List virulence factors of peudomonas

Answer 16

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

Question 17

Mention biochemical identification for Pseudomonas aeruginosa

Answer 17

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

Question 18

Mention virulence factors of S.saprophyticus

Answer 18

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

Question 19

Describe identification of S.saprophyticus

Answer 19

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

Question 20

Describe general morphologi of enterococci

Answer 20

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

Question 21

Describe growth of enterococci on culture media

Answer 21

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

Question 22

Describe biochemical identification of Enterococci

Answer 22

Catalase -ve, rapid reduction bleaching of litmus milk

Question 23

UTI due to candida is associated with…….

Answer 23

Urinary catheters, pregnancy, Abx, immunosuppressive drug administration

Question 24

Describe culture media chchs of Candida albicans

Answer 24

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

Question 25

Diagnostic specimen of UTI is…… Mention its tests

Answer 25

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

Question 26

The presence of ………is indicative of significant bacteriuria

Answer 26

10^5 CFUs

Question 27

Sterile pyuria is caused by……

Answer 27

M.tuberculosis

Question 28

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

Answer 28

Trimethoprim-sulfamethoxazole/nitrofurantoin Fluoroquinolones (cipro/levo)

Question 29

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

Answer 29

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

Question 30

Cause of Acute poststreptococcal glomerulonephritis

Answer 30

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)

Question 31

What is the laboratory diagnosis of acute poststreptococcal glomerulonephritis?

Answer 31

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.

Question 32

Mention urinary tract infections caused by viruses

Answer 32

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

Question 33

Describe pathogenesis if BK virus

Answer 33

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.