A computational quest for identifying potential vaccine candidates against Moraxella lacunata: a multi-pronged approach.

Moraxella lacunata is an emerging gram-negative bacterium that is responsible for multiple nosocomial infections. The bacterium is evolving resistance to several antibiotics, and currently, no effective licensed vaccines are available, which warrants the search for new therapeutics. A multi-epitope-based vaccine has been designed for M. lacunata. The complete proteome of M. lacunata contains 10,110 core proteins. Subcellular localization analysis revealed the presence of five proteins in the extracellular matrix, while 19 proteins were predicted to be located in the outer membrane, and 21 proteins were predicted to be located in the periplasmic region. Only two proteins, the type VI secretion system tube protein (Hcp) and the transporter substrate-binding domain-containing protein, were selected for epitope prediction as they fulfilled all the criteria for being potential vaccine candidates. Shortlisted epitopes from the selected proteins were fused together using "GPGPG" linkers to overcome the limitations of single-epitope vaccines. Next, the cholera toxin-B adjuvant was attached to the peptide epitope using an EAAAK linker. Docking analysis was performed to examine the interaction between the vaccine and immune cell receptors, revealing robust intermolecular interactions and a stable binding conformation. Molecular dynamics simulation findings revealed no drastic changes in the binding conformation of complexes during the simulation period. The net binding free energy of vaccine-receptor complexes was estimated using the molecular mechanics energies combined with the Poisson-Boltzmann and surface area continuum solvation (MM-PBSA) method. The reported values were -586.38 kcal/mol, -283.74 kcal/mol, and -296.88 kcal/mol for the TLR-4-vaccine complex, MHC-I-vaccine complex, and MHC-II-vaccine complex, respectively. Furthermore, the molecular mechanics energies combined with the generalized Born and surface area continuum solvation (MM-GBSA) analysis predicted binding free energies of -596.69 kcal/mol, -287.39 kcal/mol, and -298.28 kcal/mol for the TLR-4-vaccine complex, MHC-I-vaccine complex, and MHC-II-vaccine complex, respectively. The theoretical vaccine design proposed in the study could potentially serve as a powerful therapeutic against targeted pathogens, subject to validation through experimental studies.Communicated by Ramaswamy H. Sarma.

Eculizumab-Associated Moraxella lacunata Bacteremia and Systemic Inflammatory Response Syndrome in a Toddler with Atypical Hemolytic Uremic Syndrome.

Moraxella lacunata, a low-virulence Gram-negative coccobacillus, is classically associated with conjunctivitis and upper respiratory tract infections; systemic infections such as sepsis have rarely been reported, especially in children. We describe a 28-month-old girl with atypical hemolytic uremic syndrome and stage II chronic kidney disease on long-term eculizumab therapy who presented with systemic inflammatory response syndrome and was found to have Moraxella lacunata bloodstream infection. Eculizumab, a humanized monoclonal anti-C5 antibody, has been associated with susceptibility to infections with encapsulated bacteria, especially Neisseria meningitidis. This is the first report of an invasive bacterial infection with Moraxella lacunata in a pediatric eculizumab recipient.

Moraxella lacunata infection accompanied by acute glomerulonephritis.

Moraxella lacunata (M. lacunata) is a Gram-negative bacterium, which rarely causes serious infection. This is a rare case report of acute glomerulonephritis diagnosed by pathological findings in a child accompanied by M. lacunata infection. The patient showed hematuria, proteinuria and hyperkalemia requiring emergency hemodialysis. After hospitalization, M. lacunata bacteremia became apparent. Pathological findings showed an increase in glomerulus inflammatory cells and glomerular C3 deposition was observed in the renal tissue biopsy. Final diagnosis was endocapillary proliferative glomerulonephritis. Clinical reports of M. lacunata infection requiring emergency hemodialysis in children are rare. Previous reports have suggested that lowered immune competency with chronic kidney disease may be a risk factor associated with serious invasive cases of M. lacunata infection. However, detailed clinical laboratory data and pathological findings have not been identified in previous case reports. Our case directly indicated complement activity and acute glomerulonephritis with M. lacunata infection. Although there are various causes for acute glomerulonephritis, infection-related glomerulonephritis (IRGN) is an important concept. M. lacunata infection might have a potential risk for IRGN with dysregulation of complement activity leading to serious and invasive clinical conditions than previously considered.

Identification of Moraxella lacunata from pulmonary abscesses in three zoo herbivores.

Although Moraxella lacunata causes conjunctivitis, keratitis, endocarditis, and otolaryngitis in humans, its infection is rare in animals. We report three cases of asymptomatic pulmonary abscesses caused by M. lacunata in zoo herbivores, including two elks (Cervus canadensis) and a common eland (Taurotragus oryx). In all cases, macroscopic findings included coalescence of lung lobes and severe pulmonary abscesses filled with cheese-like materials in cysts. Microscopic findings included pneumonia characterized by marked fibrin exudates in alveolar spaces and infiltration of inflammatory cells. M. lacunata was identified in bacterial cultures from pulmonary abscesses using biochemical API 20NE system. M. lacunata is rarely isolated from zoo animals; however, herein, we describe the first report of pulmonary abscesses caused by M. lacunata infection.

Moraxella lacunata infection associated with septicemia, endocarditis, and bilateral septic arthritis in a patient undergoing hemodialysis: a case report and review of the literature.

We report the first case of both endocarditis and bilateral septic arthritis in a patient caused by Moraxella lacunata and successful management of the infection with antimicrobial therapy. The route of entry leading to bacteremia may have been the oral cavity given the poor oral hygiene of the patient as evidenced by bleeding gums. We hypothesize that the bacteremia led to septic arthritis and mitral valve infective endocarditis. In this case report, we also review the literature on M. lacunata infections and conclude that this organism should be considered in bilateral septic arthritis in a patient with underlying heart abnormalities and/or with renal failure.

A rare case of Moraxella lacunata producing combined native mitral and aortic valve endocarditis.

We describe a case of infective endocarditis due to Moraxella lacunata involving the native mitral and aortic valves, complicated by cerebral emboli and resultant hemiparesis. The patient was treated with ceftriaxone and gentamicin and improved. This appears to be the first case reported in the medical literature of native multivalvular endocarditis produced by this rare organism.

A Case of Septicemia Caused by Moraxella lacunata / 감염

Moraxella lacunata is part of the normal flora of the mucosal surface and skin. It is considered to have low pathogenic potential and has been known to cause eye infection but rarely systemic infection. We experienced a case of septicemia due to M. lacunata in a 28-year-old man who was admitted to our hospital due to high fever. He had been well untill 3 weeks earlier when he experienced fever. Physical examination revealed no audible heart murmur and echocardiogram revealed no remarkable abnormalities. Culture of blood revealed M. lacunata. The patient expired due to subdural hemorrhage, 12th days after admission. We report the case with a brief review of related literature.