Cephalosporin susceptibility of methicillin-resistant, coagulase-negative staphylococci.

Coagulase-negative staphylococci were tested for susceptibility to methicillin, cephradine, ceftriaxone, cephalothin, and cefamandole by standard broth microdilution. Most of the 26 methicillin-resistant isolates were susceptible to cephalothin and cefamandole, but very few were susceptible to ceftriaxone, and none was susceptible to cephradine. The proportion of bacterial cells that grew in the presence of 128 micrograms of methicillin per ml was calculated for each methicillin-resistant isolate. Those with every cell or 1 in 10 cells resistant to 128 micrograms of methicillin per ml included the isolates that were most resistant to the cephalosporins and highly resistant to methicillin. Those with 1 cell resistant in 10(5) or 10(6) cells were the isolates most susceptible to the cephalosporins, and their methicillin MICs were lower. When cells resistant to 128 micrograms of methicillin per ml were used as inocula for broth microdilution tests, resistance to cephradine remained the same, but resistance to ceftriaxone, cephalothin, and cefamandole increased significantly. Cefamandole was the only cephalosporin which retained antibacterial activity against some methicillin-resistant isolates (12 of 26). Cephradine, ceftriaxone, cephalothin, and cefamandole resistance appeared to be expressed by the same cells that expressed methicillin resistance. In this way, cross resistance was demonstrated between methicillin and the cephalosporins.     

False-positive eluate reactivity due to the low-ionic wash solution used with commercial acid-elution kits

BACKGROUND: During the use of commercial red cell (RBC) acid-elution kits for adsorption and elution (adsorption/elution) studies with anti- D, unexpected reactive eluates (anti-D) were obtained from D- RBCs. Such results were not obtained with a parallel xylene method or, historically, with heat and ether methods. STUDY DESIGN AND METHODS: Single-donor and commercial polyclonal anti-D samples were incubated with D+ and D- RBCs. Acid eluates were prepared by the manufacturers' directions. Variations in the wash step of the eluate preparation included the use of commercial kit wash solution versus phosphate- buffered saline versus solutions of various ionic strengths. RESULTS: Anti-D was eluted from 20 of 22 samples of D- RBCs after incubation with commercial polyclonal anti-D (titer 512) and from 2 of 3 samples of D- RBCs incubated with single-donor anti-D (titer 256). With a low- titer (16) single-donor anti-D, 0 of 4 eluates from D- RBCs reacted. When phosphate-buffered saline was substituted for the commercial wash solution, 0 of 11 D- RBC eluates reacted, as compared with 9 of 11 D- RBCs that yielded positive 1+(-)2+ eluates with the commercial wash solution. If the recommended initial phosphate-buffered saline wash was omitted before the use of the commercial wash solution, the eluate reactivity was stronger (2+(-)3+). When low-ionic-strength (< 0.03 M) saline was substituted, anti-D was eluted from D- RBCs. All last washes were nonreactive. Antiglobulin tests on all adsorbing D- were negative. CONCLUSION: Commercial wash solutions used for acid elution are at low ionic strength and commonly yield superior eluates, but in the presence of high-titer antibodies, false-positive eluates can result. It is our belief that the low-ionic-strength wash solution caused aggregation of IgG and nonspecific attachment of IgG on RBCs. Aggregates will contain IgG serum antibodies in proportion to the titer of the antibody. It is this nonspecifically bound antibody that is eluted from antigen- negative RBCs.     

Actuarial prediction of violent recidivism in mentally disordered offenders

BACKGROUND: Actuarial instruments may be useful in predicting long-term violence in mentally disordered patients. We compared two instruments that differ in terms of what they are designed to predict (general versus violent recividism) and the inclusion of stable mental health variables. METHOD: A large sample of mentally disordered patients were scored on two risk assessment instruments, the Violence Risk Appraisal Guide (VRAG) and the Offender Group Reconviction Scale (OGRS), based on information at the point of discharge. Their criminal histories for at least 2 years following discharge were obtained from official records. RESULTS: Both instruments were good predictors of both violent and general offending. Over shorter periods (0.85], which were significantly better than the OGRS. For longer follow-up periods the instruments had approximately equal prediction accuracy. However, both instruments predicted far more offences than were in fact recorded. CONCLUSIONS: The VRAG is a very good predictor of future violence in the UK sample. The OGRS may also be of value as it can be completed quickly and without the need for mental health variables. Caution is needed, however, as both instruments appeared to over-predict the levels of reconvictions in this sample.     

Quantification of the placebo response in ulcerative colitis

BACKGROUND & AIMS: There is consistently a measurable benefit noted among placebo users in treatment trials of ulcerative colitis (UC). The aim of this study was to define the placebo response in active UC and identify study features that influence the placebo response. METHODS: MEDLINE database was searched for placebo-controlled treatment studies of active UC. Data extraction was performed by two reviewers, and one separate investigator reviewed all trials and data extraction before data tabulation. Placebo remission and benefit rates were determined for clinical, endoscopic, and histological outcomes. Synthesis analysis on the weighted proportions from the different studies explored the placebo response as it related to eight study variables. RESULTS: Thirty-eight of 44 studies identified were included in the analysis. The clinical remission rate was 9.1% (confidence interval [CI], 6.6- 11.6) and the benefit rate was 26.7% (CI, 24.1-29.2). Similar rates were observed endoscopically and histologically. The number of study visits (< or =3 vs. >3) modified placebo response as assessed by clinical benefit (P = 0.05), endoscopic remission (P = 0.02), and histological remission (P = 0.04). Other study variables were not significant placebo response modifiers. CONCLUSIONS: In trials of active UC, the placebo remission rate is approximately 10% and the placebo benefit rate is approximately 30%. These rates are consistent regardless of assessment end point. The placebo response is greater in trials with more frequent study visits (more than three). (Gastroenterology 1997 Jun;112(6):1854-8)     

Use of 8-methoxypsoralen and long-wavelength ultraviolet radiation for decontamination of platelet concentrates

Transmission of viral diseases through blood products remains an unsolved problem in transfusion medicine. We have developed a psoralen photochemical system for decontamination of platelet concentrates in which platelets are treated with long wavelength ultraviolet radiation (UVA, 320-400 nm) in the presence of 8-methoxypsoralen (8-MOP). Bacteria, RNA viruses, and DNA viruses ranging in genome size from 1.2 x 10(6) daltons, encompassing the size range of human pathogens, were inoculated into platelet concentrates and subjected to treatment. This system inactivated 25 to 30 logs/h of bacteria Escherichia coli or Staphylococcus aureus, 6 logs/h of bacteriophage fd, 0.9 log/h of bacteriophage R17 and 1.1 logs/h of feline leukemia virus (FeLV) in platelet concentrates maintained in standard storage bags. Platelet integrity and in vitro function before, immediately following photochemical treatment, and during prolonged storage after treatment, were evaluated by measuring: (1) extracellular pH; (2) platelet yields; (3) extracellular lactate dehydrogenase (LDH) levels; (4) platelet morphology; (5) platelet aggregation responsiveness; (6) thromboxane beta-2 (TXB-2) production; (7) dense body secretion; and (8) alpha granule secretion. These assays demonstrated that this photochemical inactivation system inactivated bacteria and viruses in platelet concentrates with minimal adverse effects on the in vitro function of platelets in comparison to untreated control concentrates maintained under current, standard blood bank conditions.     

Enhanced co-stimulatory ability of synovial fluid accessory cells in rheumatoid arthritis

We have established in vitro assays that allow the examination of co- stimulatory function of rheumatoid arthritis (RA) antigen-presenting cells (APC). Synovial fluid (SF) and peripheral blood (PB) APC co- stimulatory ability was compared in the activation of peptide-specific human T-cell clones. T-cell receptor (TCR) stimulation by peptide or anti-CD3 antibody allowed the direct comparison of SF and PB APC co- stimulatory activity, separately from their ability to process antigen. SF APC from 15 RA patients consistently enhanced T-cell proliferation when compared to their PB counterparts. Moreover, increasing the numbers of PB APC present resulted in only a minor increase in T-cell proliferation, failing to achieve levels stimulated by SF APC. We propose that the enhanced co-stimulatory function of synovial APC may be a significant factor in the persistence of local immune responses in RA.