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Biomedical subjects

M W Bentzon

Publications and source records attributed to M W Bentzon.

At least 109 records · Page 6Linked to original sources
PubMed1976

Bacterial flora in relation to cataract extraction. IV. Postoperative inflammation. The role of conjunctival bacteria and certain surgical factors.

In 499 patients operated on for cataract, the clinical postoperative signs of extraocular inflammation (conjunctival hyperaemia, chemosis, discharge and oedema of the lids), the number of infiltrates around the corneoscleral sutures, and the severity of intraocular inflammation in the anterior chamber (aqueous-flare) were assessed on the fourth postoperative day and correlated with the bacterial conjunctival flora examined both qualitatively and quantitatively on the same day. Patients with potential pathogens (Staphylococcus aureus, gram-negative bacilli and streptococci) on the conjunctiva following operation did not show any increased inflammatory reactions when compared with those without such pathogen. The quantity of bacteria, i.e. number of colonies, did not appear to play a role. The reasons are discussed. The clinical postoperative inflammatory signs were further correlated with the following factors: surgical complications, quality of suturing technique, use of alpha chymotrypsin, systemic disease, sex and age. A positive correlation was found between the severity of extraocular inflammation and retained lens material and hyphaema. Furthermore, extraocular reactions were more severe in males than in females. The incidence of infiltrates around corneoscleral sutures was found to vary with age, i.e. occurred more frequently in patients less than 60 years. No relationship was found between the severity of aqueous-flare and the above mentioned factors.

Aged↗
PubMed1975

Bacterial flora of the normal conjunctiva. II. Methods of obtaining cultures.

The methods used for obtaining bacterial cultures from the normal conjunctiva were reviewed. A comparison was made between four methods; a) platinum loop, b)calcium alginate swab c) dry, and d) wet cotton wool swab, using agar (all methods) and serum-bouillon (methods b, c, d) as culture media. The comparisons were based on the isolation rate of Staphylococcus albus and corynebacteria. At the same time, four topical anaesthetics (benoxinate, tetracaine, proparacaine, cocaine) and one vital stain (tetrazolium - alcian blue mixture) instilled into the conjunctiva immediately before taking samples, were studied for their effects on the isolation rate of Staphylococcus albus and corynebacteria. For isolating Staphylococcus albus, method d was found to be superior to the others when the methods were used in the above mentioned order, and when agar was the only culture medium used. On the other hand, after instillation of the above mentioned eyedrops, causing the so-called "washing-out" effect (Fahmy et al. 1974), method a was found better than the others, providing the methods were used in the a-b-c-d order and when agar only was used. When considering the growth of Staphylococcus albus in serum boullion as well, methods b, c, and d were found equal in effect, but somewhat superior to a. Corynebacteria showed nearly the same isolation rate with all the methods before as well as after the instillation of eye drops.

Adolescent↗
PubMed1975

Bacterial flora in relation to cataract extraction. I. Material, methods and preoperative flora.

The conjunctival flora of 499 patients was studied the day before cataract extraction, no antibiotics or chemotherapeutical agents had been used before admission. Staphylococcus albus was by far the most common micro-organism (95.4%), followed by corynebacteria (44%), Staphylococcus aureus (14.9%), gram-negative bacilli (7.8%) and pneumo-streptococci (4.4%). Corynebacteria was isolated more frequently in the presence of S. albus, while S. aureus and gram-negative bacilli were found more frequently in the absence of S. albus. No relationship could be demonstrated between the occurrence of pneumo-streptococci and S. albus. The flora of the nose and skin of the face were studied and compared with the conjunctival flora, and a similarity could be observed. Furthermore, strains of S. aureus isolated at the same time from the two or three regions, in most cases, showed the same bacterio-phage type complex. The conjunctival flora was further correlated with sex, age, season, and number of polymorphonuclear neutrophils recovered from the conjunctival fluid. The incidence of corynebacteria and gram-negative bacilli was found to be higher in males, while corynebacteria was the only organism to show seasonal variation, i.e. was isolated more frequently in the second and third quarters of the year. No correlation could be found between age or number of neutrophils.

Adult↗
PubMed1975

Bacterial flora in relation to cataract extraction. II. Peroperative flora.

The peroperative flora of 499 patients undergoing cataract extraction was studied with local bacterial cultures taken at the beginning and end of surgery and compared with the preoperative flora examined previously (Fahmy et al. 1975 b) on admission the day prior to surgery. The local application of a single dose of oxytetracycline - polymyxin B, approximately 18 hours before surgery, significantly reduced the incidence of bacteria at the time of surgery. However, 92% of the conjunctivas examined immediately before operation proved to harbour one or more kinds of microorganisms. Futhermore, 61% of the wound sites were found to be contaminated with bacteria at the conclusion of surgery. The reasons are discussed. The origin of Staphylococcus aureus isolated peroperatively from the conjunctiva and wound site was studied. The great majority of strains could be traced to the patient's own conjunctiva preoperatively. In a few cases S. aureus was traced to the patient's own nose, skin of face or to the surgeon's nose. The air of the wards and operating theatre as well as the hands and gloves of surgeons and assistant nurses apparently did not play any role as a source of S. aureus infection.

Adult↗
PubMed1975

Bacterial flora in relation to cataract extraction. III. Postoperative flora.

The conjunctival flora of 499 patients operated for cataract was studied on the 4th and 7th postoperative days and compared with the flora examined previously on admission to the hospital and at the time of surgery (Fahmy et al. 1975b, c). Antibiotics had been administered approximately 18 hours before operation, at the conclusion of surgery, and then on the 4th postoperative day after the cultures had been taken. After a significant fall in incidence, including all kinds of bacteria at the time of surgery (Fahmy et al. 1975c), Staphylococcus albus showed an increase in incidence on the 4th postoperative day to the level found on admission. Corynebacteria and gram-negative bacilli likewise showed increasing incidence but not to the level of admission. The incidence of Staphylococcus aureus and streptococci remained unchanged. On the 7th postoperative day, S. aureus showed a fall in incidence while other bacteria had largely the same incidence as that of the 4th postoperative day. The origin of S. aureus isolated postoperatively from the conjunctiva was studied, and showed that the great majority of strains were similar to those found on the patient's own conjunctiva preoperatively. In a few instances, S. aureus could be traced to the patient's own nose or to the noses of some of the nurses. The air of the wards, eye drops or ophthalmic ointments used in the treatment of the patients apparently did not play any role as a source of S. aureus infection. Cultures obtained on the 4th postoperative day showed only a minor relationship to the flora of the wound site observed at the conclusion of surgery.

Air Microbiology↗
PubMed1971

The international reference preparation of influenza virus haemagglutinin (type A).

This paper describes the international collaborative assay that led to the establishment in 1967 of the International Reference Preparation of Influenza Virus Haemagglutinin (Type A) and the studies completed during the following years on the use of the preparation for evaluating the haemagglutinin content of 46 influenza virus vaccines in terms of international units. The WHO Expert Committee on Biological Standardization (1967) defined the International Unit as 0,09361 mg of the International Reference Preparation.Altogether 14 laboratories in 12 countries took part in one or both studies, using a total of 24 methods (HA titrations and, in a few cases CCA titrations). Major differences in the HA titres were found between laboratories, while the potencies (the haemagglutinin content values) relative to the International Reference Preparation were free from most of these differences. Haemagglutination titres varied over a range factor up to 50, while the corresponding relative "potencies" varied with a factor of only 2. The CCA method used in a few laboratories gave results close to the lowest haemagglutination titres and showed relatively small variations between laboratories. The analyses of variance disclosed differences in the variation within laboratories, but for the majority of the laboratories the variation allowed an overall estimate of a standard error.The calculation of haemagglutinin content (in IU) from relative potencies is described. Advice is given on the selection, preparation, and titration of a local reference vaccine with a view to expressing its haemagglutinin content in international units.The test results with 46 local vaccines are also given. The deviations of the relative potencies from the average per vaccine showed a distribution with eight major discrepancies instead of the expected one. The background for these cases is discussed.

Agglutination Tests↗
PubMed1970

International reference preparation of rheumatoid arthritis serum.

The National Institute for Medical Research, London, England, was requested by the WHO Expert Committee on Biological Standardization to arrange a collaborative study of the serum pool they had obtained, to determine its suitability to serve as an international reference preparation of rheumatoid arthritis serum. A batch of this serum was assayed by 11 laboratories in 7 countries against 30 test preparations. On the basis of the results obtained, the serum has been established as the International Reference Preparation of Rheumatoid Arthritis Serum and the International Unit of Rheumatoid Arthritis Serum has been defined as the activity contained in 0.171 mg of the international reference preparation.A description is also given of the British reference preparation of rabbit antibody to sheep red blood cells (amboceptor) and this material was also tested in the collaborative study.

Animals↗