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This is a series of lectures on microbiology, useful for undergraduate medical and paramedical students
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Urinary Tract Infection
Dr. Ashish Jawarkar, M.D.
Urinary tract
Urinary Tract Infection
Upper urinary tract Infections: Pyelo-nephritis Ureteritis
Lower urinary tract infections Cystitis (“traditional” UTI) Urethritis (often sexually-transmitted)
Ascending UTI
Descending infection
Hematogenous spread Chronically ill or immunosuppressed
patients
Causes
Stasis of urine (enlarged prostate etc.) Sexual activity Pregnancy Catheterisation Stones
5-7% pregnant women may present without symptoms
May lead to prematurity and perinatal death
Hence mandatory to screen all pregnant women
Symptoms of Urinary Tract Infection
UPPER UTI Dysuria (burning micturition) Increased frequency
LOWER UTI Fever Flank pain
Agents of UTI
Most common – E coli Community acquired
E. coli Enterobacter
Hospital acquired Klebsiella S. aureus Pseudomonas
Lab diagnosis
Urine can get contaminated while passing
Sterile wide mouthed containerMid stream clean catch specimen First portion – bacteria from distal
urethra Processed within 2 hours
Significant bacteriuria
>1,00,000 bacteria per ml Counts <1000 are due to contamination Counts between 1000 and 1,00,000 may
be significant, have to be co related clinically and by repeat culture
Other methods for collection
Suprapubic aspiration
Percutaneous nephrostomy
catheter
Culture
Blood agarMc conkey agar
Antibiotic susceptibility testing
Screening tests
Nitrite test TTC test Demonstration of bacteria in wet film
Wet mount
Strips
Family enterobacteria
Include E. coli Klebsiella Proteus
Escherichia Coli
Named after Escherich who first discovered the colon bacillus
Lives in intestine, passed in feces
Test for contaminated water supply
E coli testing in water
Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
Morphology
Gram negative rod Singly or in pairsMotile
Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
Growth characteristics
Good growth on ordinary media Hemolytic on blood agarMac conkeys agar, pink colonies
Blood agar
Mac conkey’s medium
Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
IMViC test
I - IndoleM - Methyl red Vi - Voges-Proskauer C - Citrate utilisation
To differentiate between enterobacteria
Klebsiella IMViC
Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
Resistance
Resistant to multiple antibiotics Due to production of beta lactamase
which inactivates penicillin and cephalosporins
Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
Pathogenicity and virulence
Surface antigens O and K O antigen – prevents phagocytosis,
endotoxic activity K antigen – also protects against
phagocytoisis Fimbria – important in UTI Toxins – beta lactamase
Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
Epidemiology
Inhabit the colon Spread via contaminated water/food
Diseases caused
UTI Precipitated by
Prostate enlargement Pregnancy Calculi
Peritonitis and bowel abcessesMeningitis in new born Septicemia
Morphology Growth characteristics Biochemical reactions Resistance Pathogenicity and virulence Epidemiology Diseases caused Laboratory diagnosis Treatment
Treatment
Ampicillin + clavulanic acid ImipenemMeropenem
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