MMIC dPBL Case 3

Learning issues:
1) Identify suspected microbial agents
2) Conduct self-directed learning based on specific case and symptoms
3) Propose relevant tests according to suspected causative agents

Keywords:
Female, 67 years, Fever, Chills, Bladder distension, Indwelling catheter, Urinary tract infection, Urine specimen

Patient's Particulars
Name: Maisy Hong
Age: 67 years old
Sex: Female

Clinical Diagnosis
Complaints: Fever, chills, bladder distension (inability to urinate)
Diagnosis: Urinary tract infection (UTI)
Note: On indwelling catheter (a urinary catheter is a plastic tube which is inserted through a patient's urinary tract into their bladder)

UTI can be grouped as either lower or upper UTI. Common symptoms of lower UTI (e.g cystitis, urethritis) in adults include back pain, hematuria, cloudy urine, inability to urinate despite the urge, fever, frequent urination, malaise and dysuria. Symptoms that indicate upper UTI (e.g pyelonephritis) in adults include chills, high fever, nausea, pain below the ribs and vomitting.

Possible causative bacterial agents:
Gram-positive: Staphylococcus sp. (Staphylococcus saprophyticus), Enterococci sp.
Gram-negative: Enterobacteriaceae sp. (Escherichia coli, Proteus sp. , Providencia sp. , Morganella sp. , Serratia sp.) , Pseudomonas sp. (Pseudomonas aeruginosa), Acinetobacter sp.

Catheter-associated urinary tract infections are caused by a variety of pathogens, including Escherichia coli, Klebsiella, Proteus, Enterococcus, Pseudomonas, Enterobacter, Serratia, and Candida. E. coli appears to be the most common cause of UTI whereas S. saprophyticus is the second most frequent causative organism of uncomplicated UTI, though more commonly seen in young, sexually active women.

Laboratory investigations:
- Enterobacteriaceae
Culture: On MacConkey, Eosin Methylene Blue agar
Identification: Gram-negative; Various biochemical identification
- Enterococci
Culture: On sheep's blood agar (showing gamma-hemolysis)
Microscopy: Gram-positive cocci
- Staphylococcus saprophyticus
Culture: On sheep's blood agar, culture with 7.5% NaCl and mannitol, non-selective media (aerobically & anaerobically)
Microscopy: Gram-positive cocci (cluster)
Identification: Positive urease, beta-galactosidase, acetoin production, novobiocin resistance
- Pseudomonas
Culture: On sheep's blood, MacConkey agar under aerobic incubation
Microscopy: Gram-negative bacilli
Identification: Positive oxidase reaction

References
- www.google.com > "urology" > sponsored links: Urologist in Singapore
- www.google.com > "indwelling catheter + urinary tract infection" > Guideline for Prevention of Catheter-associated Urinary Tract Infections
- www.wikipedia.org
- Murray, P.R., Kobayashi, G.S., Pfaller, M.A., Rosenthal, K.S. (1994). Medical Microbiology Second Edition. London: Mosby-Year Book, Inc.



Tan Yi Wei Alex
TG02 0503222B