Choledocholithiasis is still considerably observed after cholecystectomy and stones can be either old or newly formed [5]. In the present case, the remote history of cholecystectomy signified the stones on the CBD as de novo choledocholithiasis.

During cholecystectomy and in a case of retained CBD stones, the trans-papillary biliary stenting after CBD compression is considered as an attractive option to avoid T-tube–related complications [6]. Furthermore, it eases clearing the CBD from any calculi during a planned ERCP to retrieve the intraoperatively applied trans-papillary stent [7]. In the present patient, it is clear that the surgically placed stent had been forgotten for 20 years.

Neglected biliary plastic stents may act as a core of matrix for lithogenesis triggered by partial obstruction and slowing of the bile flow [8]. In that milieu, the long-retained biliary stent can foster bacterial proliferation and release of the enzyme beta-glucuronidase, and subsequent precipitation of calcium bilirubinate that then aggregated into stones by an anionic glycoprotein [9].

The initial non-resolution of the abscess despite the pigtail drainage and culture-sensitivity-guided antibiotics then the cholangiographic picture and rapid resolution after adequate biliary drainage, all prove a communication of the abscess with the intrahepatic biliary system.

The mechanism that would explain the post-COVID liver abscess formation in this patient is apparently hard to reach. One speculation could be the immune evasion which perpetually was described as a sequel of SARS-COV2 infection. The virus-mediated immunosuppression enables opportunistic bacteria to colonize vulnerable tissues in the affected patients [10]. The forgotten stent, the partially obstructed biliary system, the new calculi, and the surrounding liver tissue all were providing such vulnerability to post COVID-19 bacterial infection.

In viral pandemics, bacteremia particularly with Staphylococcus aureus has been long documented and accused of the associated morbidity and mortality [11]. Severity of the disease and mortality in Spanish flu (1918–1919) and the H1N1 influenza pandemic (2009–2010) are largely attributed to secondary bacteremia [12]. In the recently published reports, staph aureus bacteremia has been documented in patients infected with SARS-CoV-2 [13]. Two reports from New York City have documented bacteremia in patients who suffered from COVID-19. Sepulveda et al. reported that 1.6% of COVID-19 patients had bacteremia, with S. aureus accounting for 13% of these bacteremias [14]. Nori et al. reported that 1.9% of COVID-19 patients can develop bacteremias [2].

In recent years, biliary tract disease is the most common source of pyogenic liver abscess [15]. In such a condition, abscesses are usually multiple; however, solitary abscess can occur because of surgical manipulation or indwelling biliary stents [16].

Thus, another speculation in the presented case is that COVID-19 pneumonia-associated systemic bacteremia along with hematogenous dissemination can be the background pathology behind bacterial cholangitis and abscess formation.

E. coli is the prevalent liver abscesses pathogen and had been incriminated in triggering right lobe solitary abscesses [17, 18].

COVID-19 had been convicted in many liver derangements starting from just elevated liver enzymes up to acute fulminant liver failure supporting the hepatic injurious nature of the virus [19, 20]. A condition might be the clue of this case, as the ongoing COVID-19 hepatic injury paved the way to be the bed for E. coli proliferation and invasion in an immunocompromised patient with an overlooked biliary stent.

The presenting case is exceptional for the asymptomatic de novo choledocholithiasis projecting over the 20-year forgotten surgically applied trans-papillary stent. Also, the post-COVID cholangitic abscess was over-heading a quiescent biliary disease.