Urinary Tract Infections

Question 1

Staphylococcus saprophyticus

Answer 1

Gram pos cocci, catalase pos

Normal genitourinary flora in some women
Overgrowth
Young, sexually active women

ACUTE URETHRAL SYNDROME (common cause of “honeymoon syndrome”; may cause CYSTITIS
Culture –novobiocin resistant, coagulase negative; non-mannitol fermenter

Appropriate Antibiotics (relatively easy to treat)
Personal hygiene, douching (controversial)/antibiotics after intercourse

Question 2

Uropathogenic Escherichia coli

Answer 2

Gram neg bacilli (rod); ferments lactose

Colon of some patients

Autoinoculation via fecal contamination of urethra

Females

H fimbrae – contributes to cystitis
P fimbrae – contributes to pyelonephritis

CYSTITIS AND PYELONEPHRITIS
Oxidase negative, MacConkey agar – lactose fermentation, rapidly Indole positive

Appropriate antibiotics
Proper hygiene, avoid catheterization if possible

Question 3

Proteus spp

Answer 3

Gram neg bacilli (rod); oxidase negative; lactose non-fermentor

Normal flora of colon in some patients
Autoinoculation; nosocomial

Anyone w/ chronic kidney infections is at increased risk of progressing to pyelonephritis from this and other organisms; tough to treat

Urease production contributes to formation of Struvite stones w/ “coffin lid crystal”- kidney stones (magnesium ammonium phosphate); breaks down urea

CYSTITIS; PYELONEPHRITIS +/- Nephrolithiasis
Clinical presentation; oxidase negative, urease positive, swarmer, lactose non-fermentor

Appropriate antibiotics
Good personal hygiene, prompt treatment of cystitis, preventative therapy if the patient has had a history of recurrent infections

Question 4

Enterococcus faecalis

Answer 4

Gram positive cocci, catalase negative,
Lancefield group D

Normal flora; GI tract

Autoinoculation, nosocomial infections

Hospitalization, catheterization

CYSTITIS and PYELONEPHRITIS
Catalase negative, Culture (ENT) Bile esculin positive, Lancefield Group D positive; also survives in elevated salt (6.5% - MSA had 7.5-10% salt)

Dual Tx w/ appropriate antibiotics (high dosage – possibly 10x MIC used against other streptococcal spp.)
Hygiene; sterile techniques in hospital

Question 5

Klebsiella Pneumoniae

Answer 5

Gram negative bacilli (rod), polysaccharide capsule

GI tract; less frequent in respiratory tract
Autoinnculation
Nosocomial

CYSTITIS and PYELONEPHRITIS
Culture: oxidase negative, lactose fermentor, indole negative; “oozing” colonies; visible unstained capsules on gram stain

More difficult due to multiple drug resistance inherited via R-plasmids; inherent resistance to ampicillin
Hospital infection control

Question 6

Pseudomonas aeruginosa

Answer 6

Gram negative bacilli (rod), strict aerobe, oxidase positive

Soil, water, rare human carriage (Transient colonization in URT and GI tracts of hospitalized patients)

Water aerosols, direct contact into wounds

Patients with underlying chronic disease

Capsule, Biofilm (slime layer, quorum sensing), efflux pumps (remove antibiotics)

Pigments: Pyocyanin and Pyochelin (Proinflammatory, disrupt epithelial cell function); Unique Exotoxin A (Inhibits protein synthesis via ADP ribosylation of EF-2)

Exoenzymes: Phospholipase C, Rhamnolipid, leukocidins, proteases

CYSTITIS AND PYELONEPHRITIS (most often nosocomial)
Culture and sensitivity; natural fluorescence under UV light; oxidase positive; lactose non-fermentor

Combo antibiotics; anti-pseudomonal Beta lactams plus aminoglycosides or fluoroquinolones (lots of multidrug resistant strains)
Avoid exposure; judicious use of antibiotics; hospital infection control

Question 7

BK virus (Papovaviridae)

Answer 7

Ds DNA naked virus, life-long infections

Humans; 80% of adults worldwide seropositive; no evidence of disease in immune competent population

Transmission: Not definitively established; person to person

Renal transplant, immunocompromised (remains latent in the lymphocytes, urogenital tract, and brain of its host but may be reactivated if the host becomes immunocompromised)

BK-ASSOCIATED NEPHROPATHY (BKAN) - ureteral stenosis
Asymptomatic or mild upper respiratory in healthy; Renal disease in immunocompromised
Pathogenesis: Primary replication in URT, viraemia seeds to renal tissue; Ureteral stenosis, tubulointerstitial nephritis
Cytopathic changes found in renal biopsy, confirmed with immunohistochemical stains, in situ hybridization, PCR, and/or electron microscopy

Decrease immunosuppression as much as possible; cidofovir may be effective
Unknown