Immune-Related Sclerosing Cholangitis and Subsequent Pyogenic Liver Abscesses in Two Patients With Melanoma Treated by Triplet Therapy: A Case Report

Immune checkpoint inhibitors have improved the treatment of many cancers. However, immune-related (IR) adverse events can limit their use. A rare but potentially severe IR adverse event is IR-cholangitis, which is mostly induced by anti-programmed cell death 1 (PD1) antibodies and is often corticosteroid-resistant. Consequently, immunosuppressive therapy is increased, which interferes with the antitumor response and bears the risk of infection. We report on 2 patients with BRAF V600E mutant melanoma, who presented with IR-sclerosing cholangitis under triplet therapy with atezolizumab [anti-programmed cell death ligand 1 (PD-L1) antibody], vemurafenib (BRAF inhibitor), and cobimetinib (MEK inhibitor). In both cases, the administration of corticosteroids initially resulted in a marginal improvement but was followed by a rebound of biliary enzymes and the subsequent emergence of pyogenic liver abscesses with bacteremia. Liver abscesses developed without preceding invasive procedures, which implies that a more restrictive approach to immunosuppressive therapy for IR-cholangitis should be considered. To our knowledge, we report the first 2 cases of IR-cholangitis and subsequent liver abscesses without prior invasive intervention, the first cases of IR-cholangitis induced by triplet therapy, and 2 of the few anti-PD-L1 induced cases contributing to the evidence that both anti-PD1 and anti-PD-L1 antibodies induce IR-cholangitis. Treatment strategies for IR-cholangitis need to be improved to prevent life-threatening infectious complications.

Hypercapsule is the cornerstone of Klebsiella pneumoniae in inducing pyogenic liver abscess

Purpose

To investigate the mechanisms of Klebsiella pneumoniae-induced pyogenic liver abscess (PLA).

Methods

Forty-three K. pneumoniae strains from PLAs and 436 from non-PLAs were collected. Their differences were compared for virulence genes and factors, sequence types, and serotypes. Virulence genes wzi, wzy-K1, and wzi+wzy-K1 were deleted in K. pneumoniae NTUH-K2044. Various analyses, such as transmission electron microscopy, neutrophil killing tests, and mouse lethality tests, were used to confirm the consequent changes.

Results

Differences were found between K. pneumoniae strains from PLA and non-PLA samples for virulence genes and factors, including metabolism genes (allS and peg-344), capsular polysaccharide (CPS)-synthesis channel gene (wzy-K1), CPS-regulating genes (p-rmpA, p-rmpA2, and c-rmpA), and siderophore genes (iucA and iroN). When wzy-K1 was positive, the difference between PLA and non-PLA samples was only observed with c-rmpA. Δwzi, Δwzy-K1, and ΔwziΔwzy-K1 strains reverted to hypovirulence. In the Kupffer cell stimulation assay, interleukin (IL)-6, IL-12, IL-10, and transforming growth factor-β secretions were found to be equivalent in NTUH-K2044, Δwzi, Δwzy-K1, and ΔwziΔwzy-K1 groups. Lower IL-1β and higher tumor necrosis factor-α secretions were observed for Δwzi, Δwzy-K1, and ΔwziΔwzy-K1.

Conclusions

Hypercapsule production is the cornerstone of hypervirulence, regardless of exopolysaccharides. K1 K. pneumoniae-induced PLA may decrease core inflammatory cytokines rather than increase anti-inflammatory cytokines. Exopolysaccharides could also attenuate the inflammatory response to aid in the immune escape of K. pneumoniae.

Genetic and Phenotypic Characterization of Multidrug-Resistant Klebsiella pneumoniae from Liver Abscess

Cooccurrence of multidrug resistant (MDR) and hypervirulence phenotypes in liver abscess-causing Klebsiella pneumoniae (LAKp) would pose a major threat to public health. However, relatively little information is available on the genomic and phenotypic characteristics of this pathogen. This study aimed to investigate the virulence and resistance phenotype and genotype of MDR LAKp strains from 2016 to 2020. We collected 18 MDR LAKp strains from 395 liver abscess samples and characterized these strains using antimicrobial susceptibility test, string test, mucoviscosity assay, biofilm formation assay, Galleria mellonella killing assay, and whole-genome sequencing. Besides, phylogenetic and comparative genomic analyses were performed on these MDR LAKp, along with 94 LAKp genomes from global sources. Most of these MDR LAKp strains exhibited resistance to cephalosporins, quinolones, and chloramphenicol. Virulence assays revealed that only half of MDR LAKp strains exhibited higher virulence than classical MDR strain K. pneumoniae MGH78578. Importantly, we identified three ST11 KL64 hypervirulence carbapenem-resistant strains carrying blaKPC-2 and one colistin-resistant strain carrying mcr-1. Phylogenetic analysis revealed that 112 LAKp genomes were divided into two clades, and most of MDR LAKp strains in this study belonged to clade 1 (83.33%, 15/18). We also detected the loss of mucoviscosity mediated by mutations and ISKpn14 insertion in rmpA, and the latter representing a novel mechanism by which bacteria regulate RmpA system. This study provides novel insights into MDR LAKp and highlights the necessity for measures to prevent further spread of such organisms in hospital settings and the community. IMPORTANCE Pyogenic liver abscess is a potentially life-threatening suppurative infection of hepatic parenchyma. K. pneumoniae has emerged as a predominant pathogen of pyogenic liver abscess. Liver abscess-causing K. pneumoniae is generally considered hypervirulent K. pneumoniae and is susceptible to most antibiotics. Recently, convergence of multidrug resistant and hypervirulence phenotypes in liver abscess-causing K. pneumoniae was emerging and poses a major threat to public health. However, relatively little information is available on liver abscess-causing multidrug-resistant hypervirulent K. pneumoniae. In this study, we characterized phenotype and genotype of virulence and resistance of 18 multidrug-resistant hypervirulent liver abscess-causing K. pneumoniae strains collected from 395 pyogenic liver abscess cases in a tertiary teaching hospital over a 5-year period to enable in-depth understanding of this pathogen.

Clinical features and etiological analysis for 157 cases of pyogenic liver abscess

OBJECTIVES

To analyze the clinical features and the pathogenic constituent of patients with pyogenic liver abscess (PLA), and to find the risk factors of the multidrug resistance (MDR) pyogenic liver abscess (MDR-PLA) for effective therapy in the PLA patients.

METHODS

We reviewed the PLA patients with antibiotics susceptibility test, who admitted to Xiangya Hospital of Central South University from Jan. 2010 to Dec. 2019. A total of 157 cases were divided into 2 groups: an MDR-PLA group (n=52) and a non-MDR-PLA group (n=107). The clinical data such as age, symptoms, laboratory and imaging data, and etiological test especially drug sensitivity test of the 2 groups were collected. Logistic regression analysis was performed for the risk factors of MDR-PLA.

RESULTS

Anorexia (90.38%) and abdominal pain (63.46%) were more common in the MDR-PLA group than those in the non-MDR-PLA group (P<0.05). The proportions of patients with hepatolithiasis (34.62%) and biliary tract operation (38.62%) were higher in the MDR-PLA group than those in the non-MDR-PLA group (P<0.05). Klebsiellapneumoniae (59.94%) was the most common pathogen, which was sensitive to most of the antibiotics, while Escherichia coli and Enterococcus had lower drug sensitivity than Klebsiella lebsiella pneumoniae. The MDR-Enterococcus was 6.5 times of non-MDR-Enterococcus. And the multidrug resistance Klebsiella pneumoniae was 3.4 times of non-MDR-Klebsiella pneumoniae. Logistic regression analysis showed that hepatolithiasis (OR=4.895, 95% CI 1.455 to 16.463, P=0.001) and biliary tract operation (OR=3.860, 95% CI 1.156 to 12.889, P=0.004) were the risk factors for the MDR-PLA patients.

CONCLUSIONS

The PLA patients with hepatolithiasis and billary tract operation history and the pathogenic bacterium of Escherichia coli and Enterococcus bacteria should be alerted for MDR bacterial infection.

A rare case of massive pericardial effusion due to spontaneous rupture of Streptococcus anginosus group liver abscess

Purulent pericardial effusion is a rare and life-threatening complication of pyogenic liver abscess if not diagnosed and intervened early. Due to its nonspecific presentation, diagnosis of pyogenic liver abscess is challenging. Herein, we discuss the case of a 31-year-old healthy male that presented with acute chest tightness for one day in the setting of spontaneous rupture of pyogenic liver abscess and developed transdiaphragmatic extension of purulent pericardial effusion. The abscess resolved with antibiotic therapy (beta-lactam), ultrasound-guided aspiration, and pericardial window. Culture of pericardial fluid yielded the Streptococcus anginosus group. He was subsequently discharged following clinical resolution and normalization of liver function tests after 15 days of treatment. Follow-up ultrasonography revealed that the liver abscess and pericardial effusion were resolved in 8 weeks post treatment and intervention.

Are our endoscopy patients at risk for pyogenic liver abscess?

This is an editorial comment on a recent publication reporting an increased rate of pyogenic liver abscesses (PLAs) after upper gastrointestinal panendoscopy. Its aim is to critically highlight the findings, limitations and potential clinical implications of this study. Issues of the mucosal barrier, the microbial flora, administration of antibiotics and underlying diseases are discussed. The probability of PLAs after endoscopies is not exactly known and the length of the “incubation period” remains unclear, but a possible causality should already suffice to make us think how to avoid them. Especially in patients with risk factors such as diabetes mellitus, end-stage renal disease, liver cirrhosis, biliary tract infection, and malignancies, the potential risk for PLAs should be considered. Unnecessary insufflation during endoscopy (causing mucosal stretching and microscopic tears) as well as mucosal damage (by direct abrasion with the scope) should be avoided in order to limit the invasiveness of the procedure as much as possible. And, in everyday routine, it should be kept in mind that in patients after endoscopy, especially in those with a breach of the mucosal barrier and significant comorbidities, PLAs can potentially develop and require timely administration of antibiotics as well as further diagnostic and therapeutic steps.