Mediquest - October '07 Edition

AN INTERESTING CASE OF RENAL ABSCESS : By Dr.Radhakrishnan, MS, MCh [URO] CONSULTANT UROLOGIST-BRS HOSPITAL Dr.Krishnashankar, M.D,DNB. ICU REGISTRAR – BRS HOSPITAL.

A 32 years Mr.Y was admitted with high grade fever of 1 week duration. HE WAS having burning micturition of 1 week duration . He was also complaining of pain right loin which was radiating to the right loin on and off for 1 month. There was history of vomiting. There was no past history of UTI, VUR, RENAL CALCULI. He was not a diabetic.

Clinical examination
Clinically he was febrile-103.4 f, toxic, dehydrated, not anemic, no icterus
Sensorium- normal.
Cvs/rs- normal
Abdomen : tenderness in the right loin. There was ?vague mass which was palpable in the right loin.

COURSE IN THE HOSPITAL : Patient was evaluated.
1.ROUTINE investigations showed increased total count, Dc showed leucocytosis.
2. Renal Function Tests were found to be normal. Urine showed few pus cells.
3. USG abdomen showed a cortical cyst in the upper pole of right kidney.
4. Patient was initially treated with EMPIRICAL antibiotics, i.v.fluids, and antiemetics.
5. Patient Was having persistent fever spikes despite antibiotics.
6. Blood cultures grew salmonella, urine cultures grew E.coli

7. IVU reported as infected right cortical cyst with ?abcess, exerting mass effect on the superior moiety of the right pelvicayceal region. 8. CT Abdomen showed a small well defined enhancing central hyperdense attenuating lesion within right mid polar region, within posterior lip- infected cortical cyst with abscess. d/d- pylonephrotic abscess.

9. Ct guided aspiration of the pus was done and sent for cultures, which grew E.coli, CONFIRMING IT WAS AN ASCENDING INFECTION, as urine cultures also grew E.coli. 10. Since the blood cultures grew salmonella, patient was diagnosed of having Mixed infection : A. Infected Renal cortical cyst with abscess secondary to ascending infection, from the urinary tract. B. Salmonella infection.

11. After aspiration of the pus, patient was treated with I.V. antibiotics, which were modified as per sensitivity, i.v fluids, antiemetics, Antipyretics, Analgesics and antispasmodics.
12. PATIENT responded to treatment, fever spikes subsided, vomiting and loin pain subsided. Rpt USG abdomen before discharge showed organizing right renal polar abscess with decrease in the size of the abscess, hence patient was discharged.
13. This CASE IS highlighted,as infection of a cortical cyst is rare ,.Infection can occur through haematogeneous or ascending infection. In this case,it was a ascending infection, Proven by cultures. [Urine,Pus-e.coli]
14. The other aspect in this case is, that PATIENT ALSO HAD A SALMONELLA INFECTION [blood culture-salmonella], which can haemotegenously spread and can cause distant abscesses.
15. IN VIEW OF VARIABLE CULTURES,THIS patient was treated for mixed infection.

RENAL ABSCESS :
A renal abscess which is now an uncommon infection of the urinary tract, can develop by one of two general mechanisms: hematogenous spread, which usually results in a cortical abscess ; and ascending infection from the bladder, which primarily involves the medulla in most cases,causing corticomedullary abscess.

A -  Ascending infection — At present, ascending infection accounts for more than 75 percent of renal abscesses . Ascending infection, usually due to gram-negative organisms, begins in the bladder and ascends to the renal parenchyma The resultant acute pyelonephritis is followed by liquefaction which walls off the center of pyelonephritic area ,causing corticomedullary abscess.
Causative organisms:
1. Escherichia coli is responsible for 75% of infections.
2. 15-20% of cases are caused by Klebsiella, Proteus, Enterobacter, and Serratia species.
3. The remaining small percentage of infections is divided among gram-positive bacteria, including Streptococcus faecalis and, less commonly, Staphylococcus aureus.
PREDISPOSING FACTORS:
While most episodes of uncomplicated acute pyelonephritis occur in normal urinary tracts, a renal abscess is a complication of an anatomic abnormality in the urinary tract in two-thirds of cases, Such As
1. Vesicoureteral reflux,
2. Renal stones,
3. Neurogenic bladder,
4. Obstructive tumors,
5. Polycystic kidney disease.
6. Cases of renal and perirenal abscesses that occur in normal urinary tracts are observed in patients with other pathogenic risk factors, such as diabetes mellitus

B-HAEMATOGENOUS SPREAD :

Renal cortical abscess results from hematogenous spread of bacteria from a primary focus of infection outside the kidney. The source is no longer apparent in up to one third of cases at the time of diagnosis. Saureus is the etiologic agent in 90% of cortical abscess cases.
Infection of a solitary benign renal cyst or of a hydatid cyst is a rare form of renal abscess. IT MAY BE ASCENDING,OR HAEMATOGENOUS. Our case is one of these rare type OF RENAL CORTICAL CYST,getting infected by an ascending infection .

Clinical features:
1. Fever, chills, and flank or abdominal pain.
2. Dysuria and other urinary tract symptoms are variably present.
3. Nonspecific constitutional symptoms (eg, malaise, fatigue, weight loss) may manifest in patients with a chronic process,.

Medical history :
1. Most patients have a history of recurrent urinary tract infections, renal calculi, and/or prior genitourinary tract instrumentation.
2. A history of urinary tract obstruction is an important predisposing factor. Most patients report flank or abdominal pain.
3. Associated gastrointestinal symptoms, such as nausea and vomiting, are also common.

Clinical examination:
1. Signs of renal abscess vary greatly and have no specific characteristics to aid in making the diagnosis.
2. Most patients with renal infection appear ill and in distress. They often are febrile and may demonstrate signs of hemodynamic instability. Some may be tachycardic and hypotensive, manifesting the clinical picture of sepsis. Although palpable masses are not consistent findings, they are often encountered. Costovertebral angle tenderness is almost uniformly present with each type of corticomedullary infection.