Audience readings of media messages about MRSA.

This paper explores whether, and to what extent, national newspaper messages tally with public perceptions about meticillin-resistant Staphylococcus aureus (MRSA). It compares research on media messages about MRSA with interview data gathered from a demographically diverse sample of 60 people interviewed from the Greater London area. Across the interview sample there was a shared consensus that most people associated MRSA not with the history of antibiotic use, but with dirty and poorly managed hospitals. Some media messages, such as blaming MRSA on the alleged 'management culture' of the NHS, seemed to capture the Zeitgeist, whereas others, in particular the 'celebrity victims' of MRSA, did not seem to resonate with the audience. This study also found that ideas based on scientific understandings about germ theory and the immune system were held alongside folklore such as miasmic theory. The comparison of media and mind thus points to the existence of pre-scientific understandings of germs, contagion and blame in parallel with the biomedical story in the minds of the public. The findings contribute to our understanding of the public and patients' views of this infection.

In vitro release of lysozyme from monocytes and granulocytes.

When exposed to zymosan or latex particles or heat-inactivated staphylococci, freshly prepared human blood monocytes and granulocytes rapidly released a large fraction of their lysozyme content. Within 24 hours the total lysozyme activity in the monocyte suspensions tripled, while it doubled in the granulocyte suspensions, indicating synthesis of the enzyme following release. The monocytes in particular seemed to release and synthesize lysozyme without any other stimulus than contact with lymphocytes and the tube walls. Potassium caseinate in solution did not influence the lysozyme release. Myeloperoxidase and beta-glucuronidase, which in the granulocytes are kept in lysosomal fractions separate from most of the lysozyme, were neither released nor synthesized to a significant degree. Moreover, the minute amount of lactate dehydrogenase released indicated that the lysozyme release was not the result of cell lysis. Accordingly, the monocytes, which are not already stimulated by adherence to nonphagocytosable surfaces, are capable of selective enzyme release similar to that of the granulocytes.

A longitudinal study of phagocyte function in HIV-infected patients.

OBJECTIVE: To study the influence of HIV infection on phagocyte function. To date, the results of phagocyte function studies in HIV-infected patients have been contradictory. This is the first longitudinal study of these functions in HIV infection. DESIGN: We followed 50 individuals with HIV infection for 2-51 months (mean, 28 months) and examined polymorphonuclear leukocyte (PMNL) and monocyte functions at intervals of 0.5-1 years. METHODS: PMNL random migration and chemotaxis were assessed using an under-agarose method, and PMNL and monocyte oxidative metabolism by chemiluminescence production during phagocytosis of opsonized zymosan. RESULTS: PMNL random migration and chemotaxis were impaired at entry into the study by 15 and 19%, respectively. After 3 years the reduction was 35 and 32%, respectively. The mean chemiluminescence production by PMNL was reduced by 6% at entry into the study. After 4 years a decrease of 18% was observed. The decrease in PMNL function was most marked in patients with lymphadenopathy syndrome or AIDS. No significant change in monocyte chemiluminescence production was detected at any time during the study. CONCLUSIONS: A distinct and progressive decrease of PMNL function occurs during HIV infection. This may contribute to increased susceptibility to opportunistic infections in HIV-infected patients. For monocytes, chemiluminescence production is not influenced by HIV infection.

Granulocytes are more sensitive than lymphocytes to changes in EA and EAC indicator cell quality.

Granulocytes were more sensitive to age variation of EAC3b indicator cells than lymphocytes, and showed a significant decrease in rosette formation with EAC3b indicator cells more than 2 weeks old; whereas lymphocytes showed unchanged EAC3b rosette formation with indicator cells up to 4 weeks old. EAIgG rosette formation by granulocytes was less affected by the age of the indicator cells than by their degree of sensitization, with a 25% loss of rosettes after 1 dilution of the sensitizing antibody. Thus optimal sensitization is essential for granulocyte EAIgG rosette formation, and relatively fresh indicator cells for EAC3b rosette formation. Hemolysis of contaminating erythrocytes did not influence EAIgG or EAC3b rosette formation.

Factors important for the measurement of chemiluminescence production by polymorphonuclear leukocytes.

Chemiluminescence (CL) production by phagocytosing polymorphonuclear leukocytes (PMNLs) was measured by an automatic photoluminometer with built-in mixing and temperature controls. Agitation of the vials with PMNLs and opsonized zymosan particles influenced both the lag time and the CL production. Maximal production was obtained by continuous mixing of the samples, the reaction peak occurring within 6 min. Increasing the temperature from 20 to 40 degrees C also increased the CL production, and in further experiments 37 degrees C was used. Aggregation of the PMNLs was avoided by washing the cells in PBS containing gelatin 1 g/l. Glucose, Ca2+ and Mg2+ in the final reaction mixture were necessary for maximal CL responses. The measurements of CL per s up to 4 min, the peak CL value, or the integral below the CL curve up to 6 min were all linearly proportional to the number of PMNLs in the reaction mixture. Since the lag time and the time before reaching peak CL may vary, the integral below the curve up to 6 min was chosen as the mode of CL measurement. On repeated measurements the coefficient of variation was 6.3%. The mean CL integral value for PMNLs from 14 healthy individuals was 205 +/- 19 mVs, indicating a good reproducibility of the standardized assay.

Flow cytometric assay for the measurement of serum opsonins to Neisseria meningitidis serogroup B, serotype 15.

A flow cytometric phagocytosis assay has been developed for the measurement of human serum opsonins to serogroup B meningococci. Live bacteria and bacteria inactivated by heat, formalin or ethanol were labelled with fluorescein-isothiocyanate (FITC). The bacteria were opsonized with sera from patients with group B meningococcal disease and sera from healthy controls, and phagocytosis determined by combined measurements of FITC-fluorescence and forward angle light scatter. Optimal sensitivity was obtained using viable bacteria, 5% serum, 20 bacteria per leukocyte capable of phagocytosis, 7.5 min opsonization time, 5 min phagocytosis time, 37 degrees C, and continuous agitation during opsonization and phagocytosis. The opsonic activity of sera from convalescent patients was markedly higher than that of sera from patients with acute illness. Only minor day-to-day and interindividual variations were observed. The flow cytometric phagocytosis technique is a rapid and reproducible method for the measurement of serum opsonins to meningococci.

Negative selection of human monocytes using magnetic particles covered by anti-lymphocyte antibodies.

We have developed a standardized procedure for the isolation of monocytes from peripheral blood by negative selection using magnetic polymer particles coated with monoclonal antibodies against T and B lymphocytes. The average purity of the monocyte suspension was 85%, and monocyte recovery was 72% from Ficoll-Hypaque gradient separated mononuclear cells and 32% from whole blood. In a lucigenin enhanced chemiluminescence assay there was no significant difference between cells separated immunomagnetically and those separated on a gradient. Nor did electron microscopy show any significant difference in morphology between such monocytes. Negative selection using magnetic polymer particles is an efficient method for the separation of monocytes with intact morphology and function as measured by chemiluminescence.

Effects of two macrolide antibiotics on human leukocyte membrane receptors and functions.

Polymorphonuclear granulocytes (PMNs) and lymphocytes from healthy persons were incubated in varying concentrations of erythromycin and RU 28965, a new macrolide antibiotic. Incubation in erythromycin - even in high dilutions - caused a significant increase in the percentage of PMNs bearing receptors for the Fc portion of IgG (Fc gamma R) and for C3b (C3bR) as measured by rosette formation with EA (erythrocyte-antibody) and EAC (erythrocyte-antibody-complement) indicator cells. This effect could not be removed by extended washing of the cells. Incubation in RU 28965 had a similar effect, except for a decrease in EA and EAC rosetting cells at high concentrations (200 mg/l). Phagocytosis, as measured by chemiluminescence, and random migration of PMNs were unaffected by erythromycin. Chemotaxis under agarose was decreased after incubation in erythromycin or RU 28965. Erythromycin incubation increased the percentage of lymphocytes bearing receptors for sheep erythrocytes (E), but had no effect on the proportion of lymphocytes rosetting with EA or EAC, or on lymphocyte responses to mitogens PHA, conA, or PWM.

Antibiotic susceptibility of blood culture isolates of Enterobacteriaceae from six Norwegian hospitals 1991-1992.

From August 1991 to February 1992, each of the six largest hospitals throughout Norway collected 84 to 107 consecutive blood culture isolates of Enterobacteriaceae, altogether 571 isolates. The distribution of various species and genera at the different hospitals was uniform; Escherichia coli being most prevalent (57-67%), followed by Klebsiella spp. (12-18%) and Proteus mirabilis (7-11%). Twenty-one and 4% of E. coli isolates were resistant to ampicillin and cefuroxime, respectively, and 11% of Klebsiella isolates were cefuroxime resistant. Five Enterobacter isolates and one Citrobacter isolate were resistant to ceftazidime, and one Salmonella isolate was resistant to imipenem. All isolates were susceptible to ciprofloxacin and tobramycin. These results were compared with the antibiotic consumption in each hospital region. Although hospitals in the regions with the highest consumption of ampicillin tended to have a higher percentage of isolates resistant to this agent, no significant differences were found. There was no significant difference between hospitals regarding prevalence of cefuroxime-resistant isolates.

Antibiotic susceptibility of blood culture isolates of Enterobacteriaceae. A Norwegian multicenter study.

From May to November 1997 each of six major hospitals throughout Norway collected 72 to 104 consecutive blood culture isolates of Enterobacteriaceae, altogether 563 isolates. Escherichia coli was the predominating organism (69%), followed by Klebsiella spp. (15%), Enterobacter spp. (6%), and Proteus mirabilis (4%). The susceptibility of the isolates to ampicillin, cefuroxime, ceftazidime, imipenem, tobramycin, and ciprofloxacin was determined by the E-test. 37% and 7% of the isolates were resistant to ampicillin and cefuroxime, respectively, and 1% were resistant to ceftazidime and tobramycin. Only one isolate of P. mirabilis was imipenem resistant. All isolates were susceptible to ciprofloxacin. The prevalence of ampicillin-resistant isolates at each hospital varied from 21 to 45%, and of cefuroxime-resistant isolates from 3 to 9%. The results were compared with those of a similar study performed in 1991-1992. No significant changes in the susceptibility to the various agents could be demonstrated. The high frequency of isolates resistant to ampicillin has clearly limited the usefulness of this agent in the treatment of septicemia and other serious infections caused by Enterobacteriaceae.

Isoprinosine stimulates granulocyte chemiluminescence and inhibits monocyte chemiluminescence in vitro.

Isoprinosine may delay disease progression in human immunodeficiency virus infection, presumably through modulation of lymphocyte function. However, the influence of isoprinosine on phagocyte function is largely unknown. This study describes the effects of isoprinosine and azidothymidine on phagocyte chemiluminescence and migration. Incubation with isoprinosine concentrations of 250 micrograms/ml and above increased the chemiluminescence of granulocytes. Random migration of granulocytes was decreased at isoprinosine concentrations of 50 micrograms/ml and higher, but chemotaxis was not affected. Azidothymidine exerted no effect on the chemiluminescence or migration of granulocytes. For monocytes, luminol-enhanced chemiluminescence was reduced at isoprinosine concentrations of 250 micrograms/ml and above, whereas migration was not affected. These findings suggest that the immunomodulatory properties of isoprinosine may extend to phagocytic cells. This may be of significance in the treatment of immunodeficiency states.

Two-layer gradient separation of granulocytes for functional tests.

Two gradient separation techniques were compared with the dextran sedimentation method for the separation of granulocytes from blood. Both techniques gave adequate yield and excellent purity, and flow cytometric analysis of surface membrane markers gave no indication of subset selection during the procedure. Cells separated by the three methods behaved comparably in functional tests including random migration, chemotaxis and chemiluminescence. The gradient separation techniques are rapid and efficient methods for the preparation of near 100% pure granulocyte suspensions for functional studies.

IgG subclass antibodies to serogroup B meningococcal outer membrane antigens following infection and vaccination.

IgG and IgG subclass antibodies to the outer membrane antigens from Neisseria meningitidis (serogroup B, serotype 15:P1.16) were quantitated by an enzyme-linked immunosorbent assay (ELISA) in sera from 40 patients with group B:15:P1.16 meningococcal disease and 24 volunteers immunized with a serotype 15:P1.16 outer membrane vesicle vaccine. A second injection was given 6 weeks after the first immunization. Patient sera obtained two and six weeks after onset of the disease had significantly higher levels of total IgG, IgG1, IgG2, and IgG3 antibodies to the outer membrane antigens than acute sera, convalescent sera from patients with systemic non-meningococcal bacterial infections and sera from healthy controls. The levels of total IgG and IgG1 remained high one and three years later. Sera from the vaccinees showed high levels of total IgG and IgG1 6, 12 and 26 weeks after the first immunization and high levels of IgG3 6 weeks after the second immunization. No increase of IgG2 or IgG4 levels was observed in the postimmunization sera. Immunoblotting of three convalescent sera demonstrated individual patterns of IgG subclass binding to various outer membrane antigens with most distinct binding of IgG1 and IgG3 antibodies to the class I protein, the H.8 lipoprotein and the lipopolysaccharide. Since IgG1 and IgG3 are the most effective antibodies for complement activation and phagocytosis, group B meningococcal disease and immunization with the serotype 15:P1.16 outer membrane vesicle vaccine stimulate production of those IgG subclasses which have the strongest opsonic and bactericidal activity.

Budd-Chiari syndrome with obstruction of the inferior caval vein: successful treatment by cavosplenoatrial shunt.

A 27-year-old man had a 10-month history of recurrent ascites, massive edema, and extreme fatigue. The diagnosis of Budd-Chiari syndrome with severe stenosis of the retrohepatic part of the inferior caval vein had been established. Medical treatment had failed to prevent further deterioration. A single 14 mm Gore-Tex graft (W.L. Gore & Associates, Inc. Elkton, Md.) was used to establish a cavosplenoatrial shunt. The postoperative recovery was uneventful. All signs of ascites and edema disappeared within 8 weeks after surgery. In connection with repair of a ventral hernia 8 months later, a liver biopsy specimen revealed partial normalization of liver histology and an angiography demonstrated a patent shunt. Two and a half years after the initial operation he developed a bleeding peptic ulcer demanding emergency surgery. The shunt was again found patent. Three years after the first operation the patient is free of symptoms and working full time.

Serum levels of adhesion molecules and cytokines in patients with acute leukaemia.

The cytokine network and the adhesion molecule system are intercellular signal pathways. The cytokine effects are modulated in vivo by soluble cytokine antagonists, whereas the cell to cell contact mediated by adhesion molecules and their ligands may be blocked by the soluble forms of the adhesion molecules. The cytokine network is important for proliferation and cytokine secretion by acute leukaemia blasts, and membrane-bound adhesion molecules are important for blast interactions with neighbouring cells of the in vivo microenvironment. Both these signal systems are operative during the period of cytopenia following intensive chemotherapy for acute leukaemia. In the present review, we discuss the influence of disease status, chemotherapy and complicating infections on serum levels of cytokines and soluble adhesion molecules in acute leukaemia patients. We have demonstrated increased serum levels of both cytokines and cytokine antagonists in acute leukaemia patients with complicating bacterial infections during chemotherapy-induced cytopenia. Serum levels of the selectin adhesion molecules were decreased during bacterial infections in leukopenic patients compared to healthy individuals. In contrast, the intercellular adhesion molecule-1 response and the cytokine/cytokine antagonist responses were qualitatively similar to responses seen in previously healthy individuals with serious bacterial infections.

Platelet storage lesion: formation of platelet fragments with platelet factor 3 activity.

Certain samples of stored platelet concentrates exhibited marked platelet factor 3 activity. This activity was associated almost completely with platelet fragments formed during storage. Platelet concentrates containing high levels of these fragments and hence high platelet factor 3 activity were characterized after storage by alkaline plasma pH values, high levels of extracellular lactate dehydrogenase activity and relatively low cell counts.

Porphyrin-induced photodamage to isolated human neutrophils.

Human neutrophils were irradiated with light at 340-380 nm in the presence of low concentrations of protoporphyrin or uroporphyrin. At increasing light doses or increasing concentrations of protoporphyrin, the neutrophils rapidly lost the ability of locomotion. Also, neutrophil chemiluminescence and hexose-monophosphate shunt activity rapidly declined. An early event was leakage of endogenous K(+) followed by lactate dehydrogenase and at a later stage leakage of particle-bound acid phosphatase. A number of cellular enzymes were inactivated, the susceptibility to inactivation decreased in the order: succinate dehydrogenase greater than lactate dehydrogenase greater than glutamate dehydrogenase greater than acid phosphatase. Uroporphyrin had no effect on neutrophil functions, leakage of K(+), or cellular enzymes. The results suggest that photodamage to the plasma membrane and the mitochondria are earlier events than photodamage to lysosomes.

Susceptibility of 327 clinical isolates to netilmicin.

Netilmicin, a semisynthetic derivative of sisomicin, was tested against 327 isolates of Staphylococcus aureus, Pseudomonas aeruginosa and Gram-negative enteric bacilli. Seventy-two per cent of the isolates were inhibited at a concentration of 0.5 microgram netilmicin per ml, and 93% of the isolates were susceptible to 4 microgram per ml or less. The MICs of netilmicin and gentamicin for 24 Providencia and 38 Pseudomonas isolates were compared. The activity of netilmicin closely paralleled that of gentamicin, 46% of the Providencia isolates and 32% of the Pseudomonas isolates not being inhibited by 4 microgram per ml of either drug.