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Biomedical subjects

K B Hellum

Publications and source records attributed to K B Hellum.

At least 37 records · Page 2Linked to original sources
PubMed1983

Comparison of four methods for differentiation of Staphylococcus aureus from other Micrococcaceae in the routine laboratory.

Four methods for the identification of Staphylococcus aureus (tube coagulase test, thermostable nuclease test, indirect agglutination of fibrinogen coated erythrocytes and a commercial latex kit: SeroSTAT Staphylococcus Test) have been compared. Clinical isolates (698) and 40 reference strains of Micrococcaceae were included in the study together with control organisms. The coagulase test gave no false positive results but 39/406 clinical isolates of S. aureus were negative at 2h and one half were only weakly positive. At 18 h, all but 2 of 406 isolates gave a positive reaction. The thermostable nuclease test was very specific; no clinical isolates of S. aureus gave negative results and no "coagulase-negative" clinical isolates gave a definite positive reaction. The indirect haemagglutination method was sometimes difficult to interpret and frequently gave negative or doubtful results for S. aureus. The SeroSTAT test was easy to use and interpret and was specific; the method is suitable for routine laboratory use, particularly when a rapid result is desirable.

Bacteriological Techniques↗
PubMed1982

Pathogenesis of septicaemia: aspects of cellular defence mechanisms.

In the secondary defence line against bacterial invasion, the phagocytic cell systems serve as effector mechanisms of specific and unspecific immunity. In bacterial infections including septicaemia the outcome of the host-parasite interaction is determined by the ability of the mono- and polymorphonuclear phagocytes to recognize and kill the invading organisms in the presence of humoral and lymphocytic factors. The quantitative aspects of phagocytic deficiency is well recognized, in general and the risk of bacterial infection in a given patient is related directly to the duration of granulocytopenia and inversely to the number of circulating granulocytes. Reduced numbers of monocytes or, as in the splenectomized patient, lack of tissue macrophages may also add to increase suseptibility to infection with certain bacteria. Functional defects in phagocytosis in the presence of normal peripheral neutrophil and monocyte counts become increasingly important with the sophisticated procedures of modern medicine. In reviewing the functional capacity of the phagocytes it is convenient to consider four interrelated phases: 1) the vascular phase characterized by amrgination, adherence and diapedesis of the cells, 2) the chemotaxis of the directed movement of the cells to site of microbial invasion, 3) the phagocytosis or ingestion of microorganisms, and 4) the cellular factors involved in the killing and decomposition of the microorganisms. Enhanced susceptibility to infection has been related to defects in any of these functions, and the basic types of inborn or acquired abnormalities are reviewed. The problems of iatrogenic defects in antimicrobial host resistance may, hopefully, be reduced by an increasing knowledge in pathophysiology and the various steps involved in the cellular defence mechanisms.

Chemotaxis↗
PubMed1980

High dose netilmicin therapy of severe or chronic infections.

Sixteen patients with chronic or recurrent urinary tract infections, 14 with septicaemia, 2 with salmonellosis, 2 with pneumonia and 1 with acute mastitis were treated with 200 mg (2.2-3.6 mg/kg) netilmicin intramuscularly every 8 hours for 7-10 days (mean 8.8 days). 28 patients were cured, 5 showed marked improvement and 2 patients with septicaemia and severe underlying diseases failed to respond to treatment. The bacterial isolates were inhibited by 4.0 mg netilmicin/l or less. Antibiotic serum level determinations were performed in 32 patients. Mean serum concentrations of netilmicin 1 and 8 hours after injection were 12.6 and 2.0 mg/l respectively in 27 patients with normal serum creatinine levels. In 5 patients with elevated serum creatinine, mean peak and trough values were 21.5 and 5.8 mg/l, respectively. Mean netilmicin concentrations in serum and skin blister fluid obtained from 4 patients were equal 2-3 hours after injection, indicating appropriate tissue penetration. Nephrotoxicity occurred in 2 patients. Ototoxicity was not demonstrated. Netilmicin appears to be an effective and safe drug in the treatment of a variety of bacterial infections.

Adult↗
PubMed1978

Transfer of penicillin G and ampicillin into human skin blisters induced by suction.

The antibiotic concentrations in untreated and endotoxin-treated suction blisters was studied in 15 healthy adults. In a pilot study, 2 mega units of penicillin G were given as an intravenous bolus injection to two subjects. For further studies, a single dose of 800 mg bacampicillin was given orally to 13 individuals. The penicillin G concentrations in the blister fluid were highest approximately 15 minutes after the dose, and exceeded that of serum after 1.5 hours. With ampicillin the blister fluid concentration reached maximum levels after approximately 2 hours, were equal to serum levels after 3 hours, and were later persistently in excess of serum levels. The ampicillin half-life was 136 and 100 minutes in the two types of blister fluid, as compared to 65 minutes for serum. A marked differences between the antibiotic concentrations in inflammatory and non-inflammatory blisters was seen in the pilot study with penicillin G. However, in the experiments with bacampicillin, no significant difference was demonstrated. This suction blister technique appears to be a useful method for studies on extravascular antimicrobial activity in man.

Adult↗
PubMed1978

Protection of phagocytosed bacteria against antimicrobial agents.

Antibiotic sensitive Staphylococcus aureus phagocytosed by human neutrophil granulocytes were exposed to penicillin G (benzyl penicillin), gentamicin or rifampicin in concentrations from 2.5 U/ml, 2.5 microgram/ml and 0.2 microgram/ml to 250 U/ml, 250 microgram/ml and 20 microgram/ml, respectively. The bacteria were protected from the antibacterial effects of penicillin G and gentamicin. Considerable numbers of phagocytosed bacteria remained viable after 24 hours exposure to antibiotic concentrations that killed more than 99% of extracellular bacteria in less than one hour. Killing of intracellular bacteria was more pronounced with rifampicin, indicating that the penetration of this drug into the phagocytic vacuole is superior to penicillin G and gentamicin.

Anti-Bacterial Agents↗
PubMed1977

Granulocyte function in bacterial infections in man.

The reduction of nitroblue tetrazolium (NBT) dye and the phagocytic and bactericidal activities of neutrophil granulocytes from 141 patients with bacterial infections and 141 controls have been examined and related to granulocyte morphology. In 115 patients (82 per cent), the NBT reduction capacity was higher than in any control. Vacuolization of the cytoplasm and/or toxic granulation of the neutrophils were demonstrated more often in patients with high than low NBT reduction capacity. In 49 patients (35 per cent), the bactericidal activity of the neutrophils was lower than in any control. Thirty-eight patients (78 per cent) with impaired bactericidal activity had 25 per cent or more peripheral juvenile neutrophils as compared with only 12 (13 per cent) out of 92 patients with normal activity. Vacuolization of the cytoplasm and/or toxic granulation of the neutrophils were demonstrated in 28 patients (57 per cent) in whom the granulocyte function was reduced and in 26 patients (28 per cent) in whom function was normal. Within wide limits, the NBT reduction capacity increased with diminishing bactericidal activity of the neutrophils. Eighteen patients died of infection; 12 had reduced bactericidal activity. Defects in neutrophil granulocyte function caused by bacterial infection may contribute to a fatal outcome of the disease.

Abscess↗
PubMed1977

Human leucocyte migration: studies with an improved skin chamber technique.

An improved skin chamber technique has been developed for the study of localized leucocyte mobilization (LLM). Uniform "windows" of denuded dermis were produced by a suction device applied to the forearm skin, eliciting delineated areas of epidermal separation by blister formation. The acellular blister fluid, roof and basement membrane were removed, and the blister base was covered with a rubber chamber containing autologous serum as leucocyte attractant. Duplicate chambers were harvested at prescribed intervals during the first 24 hours. In 15 healthy individuals, virtually no cells were observed after 2 hours, a median of 1.9 X 10(6) after 4 hours, increasing to 3.8 X 10(7) after 24 hours. Subnormal LLM was demonstrated in three of seven patients with severe bacterial infections and in three of seven leukaemia patients. LLM was normal in eight patients with other malignancies. Ninety to 98 per cent of the cells were polymorphonuclear neutrophils and less than 1 per cent were erythrocytes. In the chamber neutrophils, vacuolization of the cytoplasm was prominent, bactericidal capacity reduced and nitroblue tetrazolium reduction increased, thus indicating functional derangement of emigrated cells compared to peripheral blood neutrophils. Simplicity and good reproducibility should make this method a valuable tool in the study of leucocyte migration.

Adolescent↗
PubMed1977

Standardization of the nitroblue tetrazolium test. Influence of pH, dye concentration and sample storage.

The influence of pH, dye concentration and sample storage on the histochemical nitroblue tetrazolium (NBT) test in 45 patients with acute bacterial infections and 51 healthy individuals has been examined. Even minor deviations in pH and NBT dye concentration markedly influenced the reduction of NBT to formazan by patient and control neutrophils, and the differentiation between results in these groups was optimal at pH 7.2 and a concentration of 0.05% NBT in the final blood-NBT mixture. Storage of heparinized blood samples for more than 2 hours at 21 degrees C and for more than 6 hours at 4 degrees C is not recommended due to overlap between results in patients and controls. The error involved in counting of NBT-positive neutrophils accounted for the major discrepancies tests in patients and controls and in tests performed on different days. The reproducibility of the endotoxin stimulated test was inferior to that of the unstimulated test.

Bacterial Infections↗
PubMed1977

Nitroblue tetrazolium test in pulmonary thromboembolism and pneumonia.

The histochemical nitroblue tetrazolium (NBT) test was performed in 88 patients with acute pulmonary thromboembolism or lobar pneumonia and in 88 healthy control subjects. In the control group, the mean NBT score was 5.4%. In the group of 55 patients with pulmonary thromboembolism the mean NBT score was 6.5% which is insignificantly different from the control mean. Only 3 of these patients had scores above normal. 35 embolism patients were followed by repeated examinations for 1 week after admission. The NBT scores remained within normal limits. 29 of the 33 patients with lobar pneumonia had elevated scores, and the mean NBT score was 33.5%. Endotoxin stimulated NBT test disclosed normal enhancement of NBT reduction by neutrophils from patients in either group as well as controls. The NBT test is of value in the differential diagnosis of pulmonary infection and thromboembolic disease. However, the results should be interpreted in the light of other pertinent laboratory and clinical findings.

Acute Disease↗
PubMed1977

Nitroblue tetrazolium test in bacterial and viral infections.

The reduction of nitroblue tetrazolium (NBT) dye by neutrophils from 379 patients with infectious diseases and 268 controls has been examined. The mean NBT score was 29.8% (72.3% positive tests) in the 231 patients with non-tuberculous bacterial infections, 9.7% (28.1% positive tests) in the 135 patients with viral infections 5.3% (1.5% positive tests) in the controls. Positive tests were demonstrated in 1 of 7 patients with tuberculosis and in 4 of 6 with mycoplasma pneumonia. Patients with urinary tract infections or septicemia had the highest percentage of positive tests, particularly when the infections were caused by gram-negative bacteria. In acute bacterial infection, the 176 patients who had not received any antibacterial therapy prior to testing had a significantly higher mean NBT score and proportion (77.8%) of positive tests than the remaining 55 pretreated patients (54.5%). Recent antibiotic treatment seriously invalidates the NBT test results. In acute viral infection, 29 of the 38 positive tests were obtained from patients with acute hepatitis (mean score 20.0%) or infectious mononucleosis (mean score 9.3%). When evaluating the test results, special attention should be paid to patients with hepatitis. Endotoxin stimulated NBT tests disclosed normal enhancement of NBT reduction by neutrophils from the patients and the controls. Cautiously interpreted, the NBT reduction by neutrophils from the patients and the controls. Cautiously interpreted, the NBT test results may be useful as an adjunct in the differential diagnosis of major bacterial and viral infections.

Acute Disease↗
PubMed1975

Neutrophil granulocyte function in the early diagnosis of acute myelomonocytic and myeloblastic leukaemia.

The phagocytic and bactericidal activities of neutrophil granulocytes from 5 patients with early acute myelomonocytic or myeloblastic leukaemia and 5 controls have been examined. In each patient the bactericidal activity was lower than in any control and the neutrophil dysfunction was demonstrated before leukaemia could be diagnosed from clinical and haematological findings. During periods of remission, the bactericidal activity was normal. Results of neutrophil granulocyte function studies may be a significant aid in the early diagnosis of acute myelomonocytic and myeloblastic leukaemia.

Adult↗