Case Presentation
A 29-year-old female presented with a complaint of recurring urinary tract infections. However, without any other known health issues, she was transferred to the hospital from another medical facility. She had a confirmed liver abscess and a staghorn stone in her right kidney. She was previously treated with intravenous metronidazole for two weeks for a suspected amebic liver abscess without improvement. Upon admission, she reported moderate pain in the right upper abdominal quadrant and a mild to moderate fever persisting for three weeks. She denied a history of renal colic, passing urinary stones, or any gastrointestinal symptoms.
Examination
On physical examination, she appeared generally well. Her temperature was 38.2°C, taken axially. Additionally, she had no signs of conjunctival jaundice. However, she exhibited marked tenderness in the right upper abdomen upon deep palpation. The Blumberg test was negative. Laboratory analysis revealed mild anaemia and leukocytosis (12.7 K/µL). Serum biochemistry parameters, including aminotransferases and total bilirubin, were within the normal range. Serum creatinine measured 0.9 mg/dL. Third-generation HIV ELISA antibody testing was negative. Urinalysis indicated moderate bacteriuria, and urine cultures were positive for Proteus spp. Strain serotyping was not performed. Blood cultures obtained before antibiotic therapy showed no growth. Serial microscopic examinations of concentrated stool samples revealed no ova or vegetative forms of any parasite.
Investigations
An abdominal ultrasound of the right upper quadrant revealed a solitary hypoechoic lesion measuring 2.7 × 1.8 × 1.5 cm, surrounded by an enhancing rim in the right hepatic lobe segments adjacent to the right kidney. The kidney was reduced in size with parenchymal thinning. A staghorn calculus occupying the renal pelvis and calyces with acoustic shadows was observed in projection to the central zone. The gallbladder was reported as unremarkable, and no biliary tree dilatation was observed. The left kidney measured 9.6 cm in its longitudinal axis, with an echographically normal appearance.
Cross-sectional CT scans confirmed a hepatic abscess, likely in liver segment VI, surrounded by an area of intermediate density corresponding to the hypoechoic rim seen on ultrasound. The coronal CT scan demonstrated a staghorn stone in the right kidney. In both views, the perirenal fat was part of the inflammatory area, forming a heterogeneous mass involving the adjacent renal parenchyma and hepatic abscess. The patient was empirically treated with a combination of 1 g/IV meropenem every 8 h and 500 mg/IV amikacin every 12 h. As urine culture and antibiotic susceptibility test results indicated good sensitivity of the isolated bacteria to both antimicrobials, the ongoing therapy was continued for 22 days and 10 days, respectively.
Follow-Up
Remarkably, complete symptom remission was achieved after the first week of therapy. Additionally, a follow-up ultrasound scan after three weeks of antibiotic treatment revealed a complete resolution of the abscess. The patient was discharged from the hospital without symptoms and was referred to the urology outpatient clinic for further management.
Liver Abscess
A liver abscess is characterized by a collection of pus within the liver parenchyma. Unless it is prevalent in regions where the amebic cause is prevalent, most liver abscesses stem from bacterial infections.
The primary source of pyogenic liver abscesses often arises from biliary tract infections, attributed to obstructions and inflammatory conditions. Alternatively, hepatic invasion can occur through less common routes, such as the spread of bacteria from distant sources (like appendicitis or diverticulitis) to the liver via the portal circulation or through the hepatic artery during bacteremia.
In rarer instances, hepatic abscesses may result from penetrating actions like infected liver biopsies or blunt events, such as biliary stenting in cases of malignancy-related trauma. Other miscellaneous causes include extension from empyema of the gallbladder, subphrenic abscess, or a cholecystogastrocolonic fistula. Recognized risk factors for liver abscesses include age over 65, male gender, diabetes mellitus, malignancy, alcoholism, cirrhosis, and liver transplantation. However, the direct extension of a perinephric focus of infection to the liver is exceedingly uncommon.
Kidney Stone
Calcium and uric stones, often noninfectious, result from imbalances promoting or inhibiting urine crystallization. In these cases, infection may arise secondarily due to prolonged obstruction, leading to bacterial overgrowth linked with urinary stasis.
Conversely, struvite and calcium carbonate-apatite stones, termed infection stones, result from recurrent infections with urea-splitting bacteria. These constitute 10–15% of all stones. These infected stones may occupy portions or the entirety of the pelvis and calyceal groups, forming partial or complete staghorn calculi. Culture analyses of staghorn calculi fragments indicate bacteria can conceal themselves in stone fissures, turning the calculi into a reservoir for infection.
Typically, renal infections are confined to the kidney, but untreated staghorn calculi, based on host immunological status, can lead to recurrent infections, pyonephrosis, and more severely, xanthogranulomatous pyelonephritis (XGPN). Peri- or perinephric abscesses often serve as the starting point for the spread through nearby anatomical structures. Peri- and perinephric abscess rupture into the peritoneum is relatively common. Extension to adjacent intestinal segments can give rise to reno-duodenal and nephrocolonic fistulae. Less frequent sites of peri- or perinephric abscesses include the retroperitoneum, psoas muscle, vena cava, and renal vein causing infectious thrombosis. Involvement of more distant structures like the spleen, prostate, lungs, and bronchi, occasionally leading to nephron-bronchial fistulae, has also been observed.
