Novel mechanism of resistance to oxazolidinones, macrolides, and chloramphenicol in ribosomal protein L4 of the pneumococcus

Two clinical Streptococcus pneumoniae isolates, identified as resistant to macrolides and chloramphenicol and nonsusceptible to linezolid, were found to contain 6-bp deletions in the gene encoding riboprotein L4. The gene transformed susceptible strain R6 so that it exhibited such resistance, with the transformants also showing a fitness cost. We demonstrate a novel bacterial mechanism of resistance to chloramphenicol and nonsusceptibility to linezolid.     

Ulcer formation and histochemical changes in rat-stomach mucosa induced by acetylsalicylic acid.

Numerous papers have emphasized the damaging effect of salicylic acid compounds on the stomach mucosa. The investigations here reported aimed at examining the effect on gastric and duodenal morphology of a moderate dose of aspirin. Oxidative enzymes were evaluated histochemically. To rats in groups of 16, aspirin tablets, placebo tablets, or the same with additional 1 cc of 0.1 N HCl, were administered twice a day for 6 weeks. Approximately 160 mg/kg/24 hrs. were ingested. Microscopy revealed severe hyperaemia along with focal gastritis in the aspirin treated animals. Chronic gactric ulcers were observed in 18 rats in the aspirin treated groups, particularly in the group where HCl was added. Ulcerations in the area of the pyloricgland occurred in the latter group only. A reduction in mucopolysaccharides was demonstrated and involved the acid as well as the neutral ones. NADH-reductase and cytochrome oxidase were inhibited not only in the surface cells but also in those in the deeper layers. The reduction in oxidative enzymes in otherwise undamaged areas suggests an interference with the cellular metabolism, probably processes in the respiratory chain which might lead to reduction in energy-rich phosphate bonds.     

Intravenous immunoglobulin ameliorates experimental autoimmune encephalomyelitis and reduces neuropathological abnormalities when administered prophylactically

BACKGROUND AND METHODS: Immunomodulation with intravenous immunoglobulin (IVIG) represents a way of interfering with the disease process in multiple sclerosis (MS). In this study, the effects of IVIG on neurological symptoms and central nervous system (CNS) pathology were evaluated in experimental autoimmune encephalomyelitis (EAE), an MS animal model. EAE was induced in susceptible Dark Agouti rats by active immunization with a spinal cord homogenate, and infusions of 1 g/kg IVIG were given prophylactically or therapeutically.RESULTS: The administration of IVIG at the time of immunization significantly suppressed the development of neurological symptoms compared with infusions of placebo (mean EAE score 0.6+/-0.3 versus 2.3+/-0.4). Moreover, the prophylactic IVIG administration resulted in a significant inhibition of the inflammatory response in CNS tissue (inflammation score 1.1+/-0.2 versus 1.8+/-0.2 after placebo). No beneficial effects were obtained by therapeutic IVIG infusions as the EAE disease course and the degree of inflammation and demyelination in the CNS were not different from animals receiving treatment with placebo.CONCLUSIONS: The present study indicates that IVIG reduces the symptoms of EAE by suppression of the CNS inflammation that characterizes CNS pathology in these animals. Taking into account data from clinical trials of IVIG in MS, the results further suggest that IVIG acts primarily during the induction phase of the immune response thus preventing the development of relapses in MS.     

Isolation of non-tuberculosis mycobacteria in treated dental unit waterlines

OBJECTIVE: The purpose of the study was to investigate the presence of non-tuberculosis mycobacteria (NTM) in dental unit waterlines that were being routinely treated with an intermittent use waterline cleaner. STUDY DESIGN: The study was conducted at a hospital dentistry clinic where immunocompromised patients are seen. Water samples from two lines on one of two dental units were taken before and after routine weekend chemical treatment. Sampling was repeated on two subsequent occasions, on the same unit, at three monthly intervals. Laboratory techniques included centrifugation and membrane filtration to detect small numbers of organisms. RESULTS: Mycobacterium simiae was isolated from one of the four pre-treatment samples and from two of the four post-treatment samples. Mycobacterium mucogenicum was isolated from one of the four post-treatment samples. CONCLUSIONS: This pilot study found that NTM were present in DUWLs that were being routinely treated with an intermittent use chemical cleaner. Practitioners are urged to understand the limitations of available DUWL treatments, and to consider the use of sterile water for non-surgical, as well as surgical, treatment of immunocompromised patients.