Jan Rollof

Interference ofStaphylococcus aureus lipase with human granulocyte function

The influence of purifiedStaphylococcus aureus lipase on granulocyte function and morphology was studied. The lipase itself was strongly chemotactic; in addition preincubation of granulocytes with low concentrations of lipase enhanced the directed movement, as assayed in the agarose system. Higher concentrations of lipase, in contrast, gave a progressive reduction of granulocyte chemotaxis; at 12µg lipase per ml, cells were almost immobilized. Phagocytic killing ofStaphylococcus aureus by granulocytes preincubated with lipase was reduced in a dose-dependent manner. At 12µg lipase per ml almost no staphylococcal killing occurred. This was mainly accounted for by a reduction of bacterial uptake, but some decrease in intragranulocytic killing was also noted. These functional alterations, which can all be ascribed to an interference with membrane functions, were associated with marked changes of the granulocyte surface structure, which was denuded and lacked normal microvilli. The effects of lipase were partly retained after heat inactivation of lipase activity, indicating that the effects of staphylococcal lipase on granulocyte function are not due to enzymatic activity alone. These effects of lipase may be an important virulence factor and contribute to the preferential location of lipase-productingStaphyloccus aureus strains at deep sites of infection.

Purification and characterization of a lipase from Staphylococcus aureus

An extracellular lipase from Staphylococcus aureus (strain FN 37) was purified to homogeneity. A cell-free culture broth was subjected to ammonium sulphate precipitation, and the lipase was isolated from the resuspended pellet by adsorption chromatography on octyl-Sepharose. The purification was 957-fold, and the recovery of the octyl-Sepharose chromatography was about 100%. The specific activity of the purified lipase was 546 mU of lipase activity per micrograms protein. The purity of the final product was documented by SDS-polyacrylamide gel electrophoresis in which a homogeneous protein band of 43 kDa was found. In gel chromatography on Sephadex G-200 the lipase eluted as a homogeneous peak with an apparent molecular mass of 110 kDa, suggesting that the lipase may exist as an oligomer in physiological media. Analysis of the amino-acid composition revealed a predominance of polar, non-charged amino acids, with serine accounting for 24 mol% of the amino-acid residues.

Positional specificity and substrate preference of purified Staphylococcus aureus lipase

We have studied the substrate preference and specificity, including positional specificity, of a lipase purified from Staphylococcus aureus (strain FN 37). This extracellular bacterial enzyme is relatively insensitive to product inhibition, and hydrolyzes tri-, di- and monooleoylglycerol in emulsified and micellar form at similar rates and without marked substrate preference. The lipase lacks positional specificity, and the hydrolysis of triacylglycerol proceeds rapidly to free fatty acid and glycerol without accumulation of intermediary products.

Recurrent Pneumonia: A Review of 90 Adult Patients

Recurrent pneumonia is still an important problem. In this retrospective study we reviewed the records of 90 patients with a history of 3 or more episodes of acute pneumonia. The 90 patients accounted for altogether 347 episodes of acute pneumonia, treated at the Department of Infectious Diseases, Lund. 12 patients died while being treated for pneumonia at the department. Pneumonia alone caused the death in 7 of these 12 patients. In all, 51 of the patients died during the 11-year study period. Death certificates, stating the cause of death, were available in 38 cases, and pneumonia was the direct cause of death in 15 patients. Most of the infections were community-acquired, only 47 were nosocomial, 20/90 patients suffered from disorders associated with immune deficiency, and 70 patients had other predisposing illnesses. We found a larger number of underlying immunoglobulin deficiencies (11 patients of 38 investigated) than previously reported. Of 13 patients without other known, predisposing conditions, hypogammaglobulinemia was found in 3 patients. We suggest that patients with recurrent pneumonia should be thoroughly investigated, in order to find previously unrecognized immune deficiency.

Severe Pasteurella multocida infections in pregnant women

We report 2 cases of severe infections due to Pasteurella multocida, both occurring during pregnancy in previously healthy women. Both women had contact with animals (dog and cat) but neither of them had been bitten. Apart from a slight decrease in IgG levels, no immunological defects could be detected. Both women had received oral phenoxymethylpenicillin in the early phase of the disease, but still fell ill with severe infections. One woman had meningitis while the other suffered from cellulitis with deep abscess formation.

Analysis of immunoglobulin isotype levels in acute pneumococcal bacteremia and in convalescence

In 48 patients with a history of a pneumococcal bacteremia, serum taken during the acute phase of the infection was analyzed for IgG and IgG subclasses. Once the patients were free of infection, a serum sample was analyzed for IgG, IgG subclasses, IgA and IgM. In an additional 20 patients, it was only possible to analyze serum from the infection-free phase. Seventeen of 48 (35 %) patients had reduced levels of total IgG or of one or more of the IgG subclasses during acute disease. Of the 48 patients in whom both acute phase and infection-free phase serum were analyzed, values of IgG (p<0.001), IgG1 (p<0.001), IgG2 (p<0.001), IgG3 (p<0.01) and IgG4 (p < 0.01) were decreased during the acute infection. During the infection-free phase, 12 of 68 (18 %) patients had a recognizable immunodeficiency, including two patients with common variable immunodeficiency. Routine screening for immunoglobulins during the infection-free period could result in the discovery of previously unrecognized immunoglobulin deficiencies in patients with a history of bacteremic pneumococcal infection.

Pasteurella multocida occurs in a high frequency in the saliva of pet dogs.

Pasteurella multocida is a frequent cause of infection after animal bites. In contrast to earlier reports, P. multocida appeared to be as common among dogs as among cats. We found 17 (81%) of 21 pet dogs to harbour P. multocida in their saliva. At normal contact, the risk of transmission from dogs to humans seems to be negligible. Only 1/27 dogs owners was found to harbour the organism. None of 13 cat owners or 23 persons without animal contacts harboured P. multocida.

In vitro activities of cefcanel and some other cephalosporins against Pasteurella multocida.

Thirty-five strains of Pasteurella multocida from humans and animals were tested for susceptibility to five cephalosporins by a broth dilution method. Cefcanel showed high activity against all isolates (MIC and MBC, less than or equal to 0.64 micrograms/ml). The corresponding figure for cefaclor and cefuroxime was 2.56 micrograms/ml. Cefadroxil and cephalexin were the least active compounds tested.

Crystal violet binding, cell surface properties and extracellular enzyme profiles of Staphylococcus aureus producing toxic shock syndrome toxin-1

Staphylococcus aureus isolated from clinically diagnosed cases of toxic shock syndrome (TSS) showed susceptibility to phage types belonging to both I and III groups (90.5%). Phage typing patterns showed a wide diversity among 87 toxic shock syndrome toxin-1 (TSST-1) positive strains isolated from different non TSS clinical sources. Toxin producing strains isolated from both TSS and non TSS showed a remarkable ability to bind to crystal violet (pattern C/D, 97.2%) incorporated into brain heart infusion agar media at subinhibitory concentrations and these isolates were traced to biotype var. hominis. The cellular fatty acid compositions of TSS and non-TSS strains belonging to the three biotypes S. aureus var. hominis, S. aureus var. bovis and S. aureus var. canis did not differ. TSST-1 producing strains demonstrated a high salt aggregation test value (above 1.5) indicating a low cell surface hydrophobicity. Both TSS and non TSS strains demonstrated a high lipolytic activity. TSST-1 positive strains in general, showed significantly higher lipase activity than strains isolated from septicemia (p less than 0.0001) and superficial (p less than 0.0001) infections. The proteolytic activity is higher among TSS (median value 0.075 U/ml) than to non TSS (median value 0.045 U/ml) strains. There was no correlation with the quantity of toxin production in vitro and to the properties described.

Are Tumor Necrosis Factor (TNF) or Cortisol of Value for the Diagnosis of Acute Septicemia

Early diagnosis is of great importance to improve the prognosis of septicemia. Traditional laboratory tests are either delayed like blood cultures, or unspecific like WBC count or ESR. In this retrospective pilot study we have assayed plasma cortisol, blood sugar and serum tumor necrosis factor (TNF) from patients with verified septicemia. With the approach used in this study none of the tests were able to differentiate between septicemia and other infectious febrile illnesses, or to predict if the causing organism was gram-positive or gram-negative.