Transcript Clinico-Pathological-Conference-30-11

Clinico-Pathological
Conference
30 Nov 2007
Case scenario
• A 60-year old man presented to the local
hospital’s Accident & Emergency Department
with a 3-day history of progressively severe back
pain, malaise, fever and rigors. He also
complained of cloudy and blood-stained urine as
well as a burning sensation on micturition.
He had been diagnosed of adult-onset diabetes
mellitus 10 years previously, but has not been
compliant with his diabetic medications. He
smokes 15 cigs/day for the last 20 years and
has a history of hyperlipidaemia.
He had also been suffering from UTIs over the
years and the episodes had become
increasingly frequent. His case notes revealed
that the last 3 UTIs over the previous 6 months
were caused by Proteus mirabilis.
Over the last few weeks, he was also experiencing
intermittent back pain associated with bloodstained urine but had not sought medical
attention until now.
On presentation, he was found to be dehydrated
and pyrexial. He had bilateral renal angle
tenderness (L>R) and suprapubic discomfort.
His random blood glucose level was 14 mmol/L
and a dipstick urinalysis was performed.
Urinalysis
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Protein,
blood,
nitrites,
WBCs in the urine.
A presumptive diagnosis of pyelonephritis and
poor glycaemic control was made. MSU and
blood cultures were sent to the laboratory. Blood
was also taken for FBC,HbA1C, electrolytes,
urea, creatinine, glucose etc. A 24-hour urine
collection was initiated to assess renal function
and creatinine clearance.
He was commenced on IV fluids and empirical
antimicrobial therapy of IV co-amoxiclav.
Q. What is the definition of a complicated
UTI?
A. A complicated UTI is an infection
occurring in a patient with structural or
functional abnormalities of the voiding
mechanism.
Q. Can you name examples of such
abnormalities?
A. 1) Structural abnormalities:
- calculi (renal, bladder, prostatic)
- strictures (urethra, ureter)
- prostatic obstruction (benign, neoplastic)
- vesicoureteric reflux
- neurogenic bladder (paraplegia, diabetes)
- indwelling urinary catheter
A. 2) common underlying diseases:
- diabetes mellitus
- sickle cell anaemia
- polycystic renal disease
- renal transplantation
- immunosuppressant therapy
Q. What organisms are commonly associated
with complicated UTIs?
A. Gram-negative bacteria:
- Escherichia coli
- Klebsiella; Enterobacter; Proteus; Serratia
- Pseudomonas aeruginosa; Acinetobacter
Gram-positive bacteria:
- Enterococcus
- Staphylococcus aureus; coag-neg staph
Yeast:
- Candida albicans
Q. What are the clinical implications of
complicated UTIs?
A. Such infections are exceedingly difficult to
eradicate without correcting the underlying
defect or removing the foreign body. Patients
with complicated UTIs are at increased risk for
severe renal damage, bacteraemia, sepsis and
increased mortality.
Q. What are the pathological features of
chronic pyelonephritis?
A. chronic cortical scarring
tubulointerstitial damage
deformity of the underlying calyx
Chronic Pyelonephritis
• The large collection of chronic
inflammatory cells here is in a
patient with a history of multiple
recurrent urinary tract infections.
• Both lymphocytes and plasma
cells are seen in this case of
chronic pyelonephritis. It is not
uncommon to see lymphocytes
accompany just about any
chronic renal disease:
glomerulonephritis,
nephrosclerosis, pyelonephritis.
• However, the plasma cells are
most characteristic for chronic
pyelonephritis.
Acute Pyelonephritis -Comparison
• Note the numerous
PMNs in the tubules.
• The neutrophils can
collect in the distal
tubules and be
passed in urine as
WBC casts.
Acute Pyelonephritis -Comparison
Areas of hemorrhage
and suppuration
grossly.
Q. What other renal complications may
result from poorly-controlled diabetes
mellitus?
A. Albuminuria / proteinuria
Nodular / diffuse glomerulosclerosis
Papillary necrosis
Arteriolosclerosis, arteriosclerosis
Atherosclerosis
Perinephric abscess
Nodular glomerulosclerosis & arteriolosclerosis
The following are the MSU results:
Microscopy
WCC
>1000 wcc/mm^3
RCC
200 rbc/mm^3
Culture
Pure growth of:
Proteus mirabilis >10^5 orgs/ml
Susceptibility
Ampicillin
R
Co-amoxiclav
R
Trimethoprim
R
Nitrofurantoin
R
Ciprofloxacin
S
Gentamicin
S
Cefotaxime
R
Q. What is your interpretation of the MSU results?
A. Significant pyuria and haematuria associated
with urinary tract infection caused by a fairly
resistant Proteus mirabilis.
In view of the above results, a diagnosis of Proteus
mirabilis UTI was made. He was continued on
IV fluids and his antimicrobial therapy was
changed to ciprofloxacin.
Over the next 2 days, his clinical condition
improved significantly. His temperature came
down to 37.5 degC and his rigors stopped. He
was less nauseated and his appetite improved.
However, he continued to have intermittent pain
around the left renal angle and flank; he also
noticed that although the urine has become less
cloudy, the haematuria has not resolved despite
antibiotic treatment.
Q. In view of his recent history and persistent
symptoms, what further investigations would
you consider?
A. Radiological investigations eg:
- ultrasonography;
- KUB x-ray; intravenous urogram;
- CT scan; retrograde pyelogram; etc.
Repeat microbiological tests ie. MSU
?Cystoscopy
Repeated dipstick urinalysis confirmed the
presence of blood in his urine.
In view of the persisting back pain and haematuria
with the background of poorly-controlled
diabetes and recurrent Proteus UTI, further
investigations were arranged. A KUB x-ray and
CT of kidneys & urinary tract were performed.
KUB
CT Scan
Radiological diagnosis: bilateral
nephrolithiasis
In view of recurrent Proteus UTIs: struvite
stone?
Staghorn calculus with areas of necrosis and
haemorrhage.
Q. What are the different types of renal stones?
A.
• Calcium oxalate / apatite stones (~75%)
• Uric acid stones (~10%)
• Struvite (magnesium ammonium phosphate)
stones (~10%)
• Cystine stones (~2%)
• Others
Q. Discuss the management of renal colic.
History, physical examination, urinalysis
↓
Presumptive diagnosis
management
↓
IV fluids, analgesia
diagnosis
↓
radiological tests, etc.
Treatment
Eg. Conservative management;
Extracorporeal shock wave lithotripsy (ESWL)
Percutaneous nephrostolithotomy
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Stone analysis;
Diagnostic evaluation for cause of nephrolithiasis
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Preventive therapy
Eg. High fluid intake, dietary changes, drug Rx.
The patient underwent ESWL to have the
renal calculi removed. Following the
procedure, he received a course of
ciprofloxacin to eradicate any persisting
bacteria.
He was informed of the importance of
maintaining good glycaemic control and
was also referred to an endocrinologist for
further management of his diabetes
mellitus.