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Eikenella corrodens as a cause of recurrent and persistent infections of the head and neck.

Four patients had Eikenella corrodens infections involving the head and neck in different ways. The organism is discussed as a pathogen in mixed infections and as the predominant organism in other processes. As part of the resident microflora of mucous membrane surfaces, it is an important potential pathogen in a number of otolaryngologic clinical settings. Careful microbiological culturing and susceptibility testing reveal the causative organism and guide the antibiotic therapy.

Adolescent↗

The role of persisting infections in the pathogenesis of pulmonary emphysema. Electron microscopy reveals a probable bacterial colonization of the alveolar space and the bronchioles.

Lung volume reduction surgery (LVRS) yields resection specimens from patients with advanced pulmonary emphysema. Regarding the development of lung function parameters, recent results obtained by light microscopy revealed an unfavorable prognosis in patients with remarkable inflammation, particularly in the bronchioli. Tissue from ten patients (alpha1-antitrypsin level in the normal range) was furthermore investigated by electron microscopy. Scanning electron microscopy shows 0.4-0.6 micron spherical bodies variably densely arranged in the whole alveolar space and in the bronchioles of all patients. These bodies are mostly seen on the microvilli of type II pneumocytes. An immunological reaction with activation of macrophages and granulocytes occurs simultaneously. Macrophages show cytoplasmic extensions to the spherical bodies, which exhibit a cellular membrane but no cellular wall. This favors the diagnosis of bacterial colonization of the alveolar space and the bronchioles by mycoplasmas or L-forms of other bacteria. As patients undergoing lung volume reduction surgery are under optimal medical treatment and without any infection clinically, these findings appear to be relevant for the pathogenesis and/or progression of pulmonary emphysema.

Acute Disease↗

Persistent infection after successful arthrodesis for infected total knee arthroplasty. A report of two cases.

Infection in total knee arthroplasty has been reported to range from 1.1% to 12.4%. The literature contains numerous articles on salvage procedures including antibiotic suppression, surgical debridement, resection arthroplasty, arthrodesis, reimplantation, and amputation. Of those knees not reimplantable, a successful arthrodesis is felt by many to give the most predictable long-term results. The majority of literature on arthrodesis for infected total knee arthroplasty concentrates on technical factors and techniques to facilitate fusion. A successful fusion is considered an end point of treatment.

Adult↗

Cystic fibrosis pathogenesis and the role of biofilms in persistent infection.

Recent work has presented definitive evidence that the Pseudomonas cells that infect the lung in cystic fibrosis grow in the biofilm phenotype. These unequivocal data establish this chronic infection of compromised hosts as the archetypal biofilm infection, which is both refractory to antibiotic therapy and barely affected by host defenses.

Biofilms↗

Persistent infection of the chin with an unusual skin pathogen (Streptococcus milleri): a sign of intraoral carcinoma.

Streptococcus milleri is a commensal of the oropharynx and gastrointestinal tract which is not generally associated with skin disease. We now report a patient who presented with a pustular mass of the chin with lower lip anaesthesia. He was initially thought to have sycosis barbae, but response to treatment was poor and lesional swabs repeatedly cultured S. milleri. After some delay, squamous cell carcinoma of the mouth, involving the mandible and overlying skin, was detected. We consider that the S. milleri either invaded through the tumour from the mouth or root canal or colonized the skin from saliva dribbled over the numb lower lip. Isolation of an unusual organism and numbness of the chin are features that should suggest the need for early radiography.

Aged↗

Scrapie prion proteins accumulate in the cytoplasm of persistently infected cultured cells.

The cellular prion protein (PrPC) is a sialoglycoprotein anchored to the external surface of cells by a glycosyl phosphatidylinositol moiety. During scrapie, an abnormal PrP isoform designated PrPSc accumulates, and much evidence argues that it is a major and necessary component of the infectious prion. Based on the resistance of native PrPSc to proteolysis and to digestion with phosphatidylinositol-specific phospholipase C as well as the enhancement of PrPSc immunoreactivity after denaturation, we devised in situ immunoassays for the detection of PrPSc in cultured cells. Using these immunoassays, we identified the sites of PrPSc accumulation in scrapie-infected cultured cells. We also used these immunoassays to isolate PrPSc-producing clones from a new hamster brain cell line (HaB) and found an excellent correlation between their PrPSc content and prion infectivity titers. In scrapie-infected HaB cells as well as in scrapie-infected mouse neuroblastoma cells, most PrPSc was found to be intracellular and most localized with ligands of the Golgi marker wheat germ agglutinin. In one scrapie-infected HaB clone, PrPSc also localized extensively with MG-160, a protein resident of the medial-Golgi stack whereas this colocalization was not observed in another subclone of these cells. Whether the sites of intracellular accumulation of PrPSc are limited to a few subcellular organelles or they are highly variable remains to be determined. If the intracellular accumulation of PrPSc is found in the cells of the central nervous system, then it might be responsible for the neuronal dysfunction and degeneration which are cardinal features of prion diseases.

Animals↗

Epitope-dependent selection of highly restricted or diverse T cell receptor repertoires in response to persistent infection by Epstein-Barr virus.

The T cell receptor (TCR) repertoires of cytotoxic responses to the immunodominant and subdominant HLA A11-restricted epitopes in the Epstein-Barr virus (EBV) nuclear antigen-4 were investigated in four healthy virus carriers. The response to the subdominant epitope (EBNA4 399-408, designated AVF) was highly restricted with conserved Vbeta usage and identical length and amino acid motifs in the third complementarity-determining regions (CDR3), while a broad repertoire using different combinations of TCR-alpha/beta V and J segments and CDR3 regions was selected by the immunodominant epitope (EBNA4 416-424, designated IVT). Distinct patterns of interaction with the A11-peptide complex were revealed for each AVF- or IVT-specific TCR clonotype by alanine scanning mutagenesis analysis. Blocking of cytotoxic function by antibodies specific for the CD8 coreceptor indicated that, while AVF-specific TCRs are of high affinity, the oligoclonal response to the IVT epitope includes both low- and high-affinity TCRs. Thus, comparison of the memory response to two epitopes derived from the same viral antigen and presented through the same MHC class I allele suggests that immunodominance may correlate with the capacity to maintain a broad TCR repertoire.

Amino Acid Sequence↗