Sven Åke Hedström

Predisposing factors, bacteriology and antibiotic therapy in 35 cases of septic bursitis.

In a retrospective study the etiology was verified in 35/52 patients with suspected septic prepatellar or olecranon bursitis. Staphylococcus aureus was the most common pathogen and 86% of them were penicillinase-producing. Other strains were streptococci. Mean age was 47 (18-83) years and males predominated (91%). Predisposing factors were seen in most cases. Preceding trauma was found in 27 and/or associated diseases (e.g. diabetes mellitus) in 11 patients. Hyperglycemia was found in 38% of the patients. Treatment with antimicrobial agents, mostly penicillins, and bursal drainage were successful in 32 cases. Two patients had local spread of the infection and 1 patient chronic bursitis.

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.

Serological Assays against Staphylococcus aureus Peptidoglycan, Crude Staphylococcal Antigen and Staphylolysin in the Diagnosis of Serious S. aureus Infections

Immunoglobulin G antibody levels against Staphylococcus aureus peptidoglycan (PG) and crude staphylococcal antigen (SA) using enzyme-linked immunosorbent assay (ELISA) and antistaphylolysin (ASTA) antibody levels by gel diffusion were determined in 53 patients with S. aureus and 54 patients with non-S. aureus endocarditis and septicemia as compared with 63 febrile control patients. The two ELISAs were the most sensitive assays indicating S. aureus endocarditis in 83% and 88% in the PG- and SA-assays, respectively. 39% of non-S. aureus endocarditis patients were positive in the PG-assay due to antibodies cross-reacting with streptococci. A 100% specificity for S. aureus infections was obtained with the ASTA test, but this assay was less sensitive. A significant rise in anti-PG or anti-SA antibody levels was not only seen among S. aureus infections but also in some streptococcal and S. epidermidis infections as well as in 3 febrile control patients. When at least 2 of the 3 assays showed positive peak antibody levels 1-4 weeks after onset of infection together with a significant rise of both anti-PG and anti-SA antibody levels the S. aureus endocarditis diagnosis was highly suggestive. Thus, we recommend the combined use of these 3 assays using paired serum samples in diagnosing serious S. aureus infections.

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.

Biochemical and Biological Properties of Staphylococcus aureus Septicemia Strains in Relation to Clinical Characteristics

166 Staphylococcus aureus septicemia strains were phage grouped and tested for lipolytic activity, protein A content, alpha, beta and delta hemolysin activity and toxic shock syndrome toxin (TSST-1) production. These strain characteristics were correlated to the clinical features of the infections. Patients infected with phage group II strains showed the lowest mortality but were more prone to develop internal abscesses. Lipolytic activity and protein A positivity was found in most strains and no correlation to phage group or clinical signs could be shown. Alpha hemolysin was the most common of the investigated hemolysins though it was only produced by 58% of 88 investigated strains. Beta and delta hemolysin production was found in 25% and 24% of the strains, respectively. The lowest frequency of alpha hemolysin production (25%) was found among phage group I strains, especially those producing TSST-1, where only 1 of 12 strains was positive. The overall frequency of TSST-1 production was 18% in 88 tested strains and most positive strains were non-hemolytic. These results indicate that hemolysin production does not seem to be required for a strain to be invasive.

Cefuroxime prophylaxis in trochanteric hip fracture operations

In a double-blind randomized study of antibiotic prophylaxis in trochanteric fractures operated on with a nail and plate, a 24-hour intravenous administration of cefuroxime 0.75 grams thrice daily (Group B) was compared with the previous regimen of cefuroxime for 24 hours plus 6 days of oral cephalexin (Group A). In each group, 56 (Group A) and 65 (Group B) patients could be evaluated. One deep infection occurred in Group B with growth of Staphylococcus aureus, and another 4 patients had discharge and cultures of which 2 showed S. aureus. In Group A, 6 patients had signs of an infection, and in 3 patients cultures were taken but were negative. There were no differences between the groups. We concluded that the prophylaxis time need not be longer than 3 days.

Nephrotoxicity in isoxazolylpenicillin prophylaxis in hip surgery

In 789 courses of antibiotic prophylaxis in hip arthroplasty surgery, either dicloxacillin (Diclocil) or cloxacillin (Ekvacillin) was used during two different time periods. The surgical methods, anesthesia, preoperative and postoperative care of the patients, and laboratory procedures were the same all the time. Changes in creatinine values were used as a method for evaluating the impact on renal function. When using dicloxacillin, a pathologic increase of creatinine was noted in 12 and 13 percent by two different calculation methods. Sixteen patients (4.2 percent) had a severe creatinine increase during the first postoperative week after dicloxacillin prophylaxis, requiring dialysis in 2 patients. Cloxacillin had only a marginal impact on renal function. Patients above aged 70 years were more vulnerable as regards renal function than younger persons, and the impairment was slightly dose related in all ages. In the dicloxacillin group, preoperative use of antiphlogistic drugs was correlated with reduced postoperative renal function.

Cefuroxime in acute septic arthritis.

Cefuroxime was used in 17 patients with clinical, bacteriological and/or laboratory signs of acute septic arthritis in comparison with 10 patients given cloxacillin and ampicillin alone, or in combination. 14 patients in the study group had positive cultures (Staphylococcus aureus, 10, S. epidermidis, 1, Streptococcus pyogenes group G, 2 and Acinetobacter, 1). Three more patients with non-bacterial arthritis were included in an antibiotic penetration study. In 6 patients serum and joint fluid concentrations of cefuroxime were repeatedly determined by an assay using high pressure liquid chromatography. After 1.5 g intravenous cefuroxime the joint fluid concentrations were 16-80 and 5-40 mg/l at 2 and 8 h, respectively, exceeding the serum concentrations during that period of time. From the clinical and pharmacokinetic data a dosage of 1.5 g cefuroxime intravenously t.i.d. is recommended to the adult patient. This high dosage resulted in primary healing in 11 patients with one relapse one year later in a patient with a knee arthroplasty. Half the dosage intramuscularly in 6 patients failed in 2. No side effects were seen during cefuroxime therapy.

Chronic progressive osteoblastic osteomyelitis: a new approach to treatment.

The clinical, histologic and radiographic picture in 16 cases in 15 patients with nonfistulating chronic progressive osteoblastic osteomyelitis of a long tubular bone which started in childhood is presented. All patients had severe pain at rest or weightbearing. Histology showed an increase of active osteoblasts. Low virulent bacteria were found in one-fourth of the patients. To reduce the osteoblastic activity, nonsteroidal antiinflammatory treatment was combined with surgical and antibiotic treatment. Eleven patients were pain-free at follow-up (average 47 months), 3 had reduced pain, and 1 patient did not respond to treatment.

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.