Case 1 Proteus mirabilis

Image A

Gram stain slide

A 70-year-old man presents with lower back and groin pain with dysuria for a week. He also complains of frequency and urgency during micturition. He had history of renal stone last year. Urine culture reveals undulating swarming margin around colonies, as shown in image A.

•Describe what is seen in Gram stain slide – Gram –ve, rod shaped, facultative anaerobic•State the most likely organism as shown in image A – Proteus mirabilis•Name the enzyme produce by this organism - Urase•Explain how this organism causing infection in this patient – Urase converts urea into ammonia and CO2. Ammonia causes the alkaline pH, promotes the formation of kidney stone (Mg NH4+ Phosphate stones?)

Image A Gram stain

Case 2: Pseudomonas aeruginosa

A 30-year-old patient presents with pyuria, fever and renal tenderness after being hospitalised for renal calculi surgery. Patient is also having a body temperature of 38.5 0C. Urinalysis gave positive result for nitrite and microscopy reveals numerous WBC casts. The isolated organism produces greenish pigment on Nutrient agar.

Identification of this organism:Oxidase - positiveMotility test - motileStrictly aerobes •State the most probable organism – Pseudomonas aeruginosa

•State the name of pigment producing by this microorganism – pyocyanin (blue-green), pyoverdin (yellow-green & fluorescent), pyorubin (red-brown) •State the source of infection in this patient – Nosocomial/Hospital acquired after 48 hours of admission

Image B

Case 3 : Escherichia coli A 28-year-old lady presents with hematuria, low grade fever and burning sensation during micturition. She has just been married for three weeks. Urine specimen collected was cloudy and strong smelling. The dipstick result reveals leukocytes esterase and “++” for nitrites but negative for others. Culture on Mac Conkey agar and Gram stain reveals organism C.

• Describe what is seen on Gram stain

Gram –ve, rod-shaped (bacilli)

• Describe the colony on Mac Conkey agar.

Dry pink colonies are seen (Lac+) – [If Klebsiella, mucoid pink colonies will be seen, also Lac+]

• Name the most probable organism.

Escherichia coli

• Which laboratory parameter stated above showed bacterial infection of the urinary tract?

Positive for nitrite

• Define hematuria

Blood in the urine

• Name one confirmatory test for this condition if the dipstick is positive for blood.

Urine microscopy – check for RBC casts?

• What is the diagnosis?

UTI, to be specific – cystitis (usually a/w honeymoon – sexually transmitted?)

Case 4: Staphylococcus aureus

A 65-year-old man with type 2 diabetes presents with right flank pain and fever. Physical examination reveals right lumbar tenderness. Full blood count shows leukocytosis and ultrasound finding confirm right renal abscess.

Image D is the gram stain of the isolated causative agent.

Describe what is seen in Image D – Gram +ve, in clustered (cocci)

State the most probable organism - Staphylococcus aureus

Name the test to confirm this microorganism – Coagulase test

State the substance in this organism that causing abscess formation – Leukocidin (leuko – leukocytes, “-cide” – killing)

Image D

Case 5 : Klebsiella pneumoniae

A 60-year-old man was

admitted to the hospital

2 weeks previously due to

head trauma.

A urinary catheter was

inserted on admission day

and remains in place.

The man develops urinary

tract infection with gram

negative bacilli.

Photomicrograph E

Photomicrograph E shows the culture of isolated organism.• Describe what is seen on culture media

Mucoid concave pink colonies• Name the culture media.

MacConkey agar• State the genus and species of this microorganism, justify your answer.

Klebsiella pneumoniae, because Klebsiella is Lac+ that produces mucoid colonies (as E. coli produces dry colonies)

• State the source of infection in this patient.

Urinary catheter • The infection in this patient is considered as nosocomial infection. Define

nosocomial infection.

Hospital acquired infection after 48 hours of admission.• State other sources of infections that can lead to nosocomial infection.

Causative agent factor – from catheter, ventilator. Patient factor – immunocompromised patient – head trauma