April 1994, Volume 44, Issue 4

Case Reports

Unusual Presentation of Acute Bacterial Focal Nephronia

M. Hammad Ather  ( Institute of Urology and Transplantation, Dow Medical College and Civil Hospital, Karachi. )
Tauqir Ahmed Rana  ( Institute of Urology and Transplantation, Dow Medical College and Civil Hospital, Karachi. )
Ali Anwar Naqvi  ( Institute of Urology and Transplantation, Dow Medical College and Civil Hospital, Karachi. )
Adibul Hassan Rizvi  ( Institute of Urology and Transplantation, Dow Medical College and Civil Hospital, Karachi. )

Bacterial nephronia - a severe form of nephritis is a rare, acute, focal or multifocal infection of the renal parenchyma, which is sometimes referred to as “pre­abscess state1’. We present a case with unusual symptomatology at onset, while the radiological features were suggestive of a mass lesion.

Case Report

A. R., 24 years old male presented with left lumbar pain, hematuria and fever of 15 days duration with intermittent vomiting. He went into acute urinary reten­tion for which a Foley’s catheter was retained for 10 days. An intervenous urography was performed and it showed bilaterally normal functioning kidneys with amass lesions on the left which was displacing the pelvicalyceal system medially.

Ultrasound (Figure 1) performed later on showed a solid mass measuring 34x60 mm with heterogenous echotexture at the mid outer portion. A pre and post contrast (80 ml 76% urograffin) CT scan (GE-9800) showed

(Figure 2) a non-enhancing mass lesion in the left kidney causing displacement of calyceal system. There was some extension of inflammatory process outside the kidney with thickening of lieno-renal ligament. The abscess was aspirated under local anaesthesia with ultrasound guidance, pus obtained grew staphylococcus aureus sensitive to of laxacin. With con­tinuous antibiotic (400 mg bd) therapy serial ultrasound confirmed the clinical impression of resolving abscess. Follow up CT scan after 14 weeks (Figure 3)

showed complete resolution of the abscess.

Discussion

Though upper urinary tract infections are common, focal bacterial nephronia is an unusual clinical occur­rence2. Usually it is focal though cases of migratory nephronia have also been described3. Though both focal and multifocal nephronia can occur in the general population, they are more common in diabetics (50% of the patients are diabetic)4. Besides diabetics, association with sickle cell disease, neuropathic bladder, outflow tract obstruction and previous episodes of pyelonephritis has been described4. The onset of  bac­terial nephromais usually abrupt. Fever (100°F +), chills, costovertebral angle pain and symptoms of cystitis is the classical presentation. It is more common in children with reflux. The mechanism is ascending infection from the lower urinary tract and there is localized segment of edematous infected kidney with heavy leukocyte infiltrate extending from papila to capsule5. The srze varies 2 to 5 cms. The presentation is similar to those of acute pyelonephritis but is usually more severe. The causative organisms include E. coli, kiebsiella, proteus and staphylococcus4,6. The diagnosis is made on radiologic findings. Urography is often misleading, findings are suggestive of mass or abscess. On ultrasound there is evidence of solid mass which is typically poorly marginated and relatively sonolucent7. The lesion often shows low amplitude echoes that disrupt the corticomedullary differentiation. Distal acoustic enhancement is not present and there is difficulty in visualization if CT scanning is not done with contrast enhancement. On CT the usual finding is wedge shaped areas of decreased enhancement without definite wall and absence of liquefaction8,9. Sometime on CT scan there are areas of high attenuation indicating haemorrhage. Gallium 67 scanning shows areas of uptake that is larger than the previously described mass10. Treatment includes hydration, parenteral an­tibiotics for one week followed by oral for another week9. Follow-up shows resolution of wedge shaped zones of diminished attentuation. It ranges from 6 weeks5,7  to 4 years6,8. We followed up our case for 12 weeks and found that after an initial acute illness the patient recovered clinically whereas sonographic recovery took over 10 weeks to show signs of recovery. Long terni follow-up studies performed in a few patients with multifocal disease have demonstrated a decrease in renal size and focal calyceal deformities suggestive of necrosis9. Failure of response should raise suspicion and alternate diag­nosis be suspected including obstructive uropathy, pen-renal abscess, renal carcinoma or acute renal vein thrombosis. Long term follow-up shows decreased renal size, focal calyceal deformities suggestive of papillary necrosis.

References

1. McCoy, R., Kurtz, A.B., Rifkind, M.D., et a). Ultrasound detection of focal bacterial nephritis (lobar nephronia) and its evolution into a renal abscess. Urol. Radiol., 1985;7:109-12.
2. Kraft, 3K. and Stamey, T.A. The natural history of symptomaticrecurrent bacteriuria in women. Medicine, 1977;56:S5-60.
3. Silverman, S.G., Pfister, R.C., Papinicalou, N., et al. Migratory lobar nepbronia. Urol. R.adiol., 1989;11:16-19.
4. Nosher J.L., Tanminen, J.L., Amorosa, J.K., et al. Acute bacterial focal nephritis. AmJ.Kidney Die., 1988;11:36-42.
5. Siegel, M.J. and Galsier, CM. Acute focal bacterial nephritis in children; significance of ureteral reflux. Am.J.Roentgenol., 1981;137:257-60.
6. Lee, J.K., McClenan, B.L., Melson, CL., et al. Acute focal bacterial nepbritis: emphasis on gray scale sonography and computed tomography. Am.J.Roentgenol., 1980;135:87-92.
7. Gold, R.P., McClennan, B.L. and Rottenverg, R.R. CT appearance of acute inflammatory disease of the renal interstitium. Am.). Roentgenol., 1983; 141:343-49.
8. Rauschkolb, EN., Sandier, C.M., Patel, S., et al. Computed tomographyof renal inflammatory disease. J.Comput.Assist.Tomogr.. 1982;6:502-6.
9. Davidson, A.). and Talner, LB. Late sequelae of adult-onset bacterial nephritis 1. Radiology, 1978; 127:367-71.
10. Hampel, N., Class, R.N. and Persky, L. Value of Gallium acintigraphy in the diagnosis of localized renal and peri-renal inflammation. J.Urol., 1980;124:311-­14.

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