Susanne Møller

BACTERIAL FLORA IN RELATION TO CATARACT EXTRACTION

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.

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.

Bacterial flora of the normal conjunctiva. I. Topographical distribution.

The bacterial flora of 100 normal conjunctivas was studied. Staphylococcus albus and corynebacteria were the most common microorganisms recovered, followed by Staphylococcus aureus, gram‐negative bacilli and streptococci. The topographical distribution of S. albus and corynebacteria on 12 different anatomical regions of the conjunctiva was examined, and showed that both bacteria occurred less frequently on the bulbar regions. No differences between the upper and lower parts, nor between the outer and inner regions could be found. A culture obtained from the lower fornical and tarsal conjunctiva revealed about 93% of S. albus and corynebacteria actually harbouring on the conjunctiva.

BACTERIAL FLORA OF THE NORMAL CONJUNCTIVA

The methods used for obtaining bacterial cultures from the normal conjunctiva were reviewed.

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.

Studies on the Development of Tuberculin Sensitivity in Immunized Guinea Pigs with Demonstration of a Close Relationship between Results of Skin Tests and the Lymphocyte Transformation Technique

The development of tuberculin sensitivity in groups of guinea pigs immunized with living BCG vaccine or with heat-killed Mycobacterium tuberculosis suspended in oil (TB) was measured by skin tests and lymphocyte transformation (LT) tests with tuberculin PPD. LT tests on lymphocytes from peripheral blood (PBL) and lymph nodes (LNL) and skin tests were carried out on different groups of guinea pigs for 1 year following immunization. Three ways of expressing the LT results were considered, i.e. as stimulation index, delta cpm and uncorrected cpm values. Since neither of the first two methods were equally applicable to all of the data, we decided to express the data as geometric means of cpm values for stimulated and control cultures, respectively. For both immunogens the sensitivity measured by PBL LT and skin tests showed a closely parallel development; LNL reactivity appeared earlier and remained at a higher level than PBL reactivity. Antibody levels in the guinea pigs were measured using a radioimmunoassay technique, were found to be dependent on the immunization period and not correlated to the cellular immunity.

Effect of 2-mercaptoethanol and mycostatin on guinea pig lymphocyte transformation: Interpretation of results depends on the method of calculation

The stimulating effects of 2-mercaptoethanol (2-ME) reported in murine cell cultures were confirmed for guinea pig lymphocyte transformation (LT). 2-ME was mitogenic for peripheral blood lymphocytes (PBL) and lymph node lymphocytes (LNL) and enhanced PPD-induced LT. The effect on LNL was dependent on the magnitude of the response of non-2-ME treated cultures. The 2-ME effect on PPD-stimulated LNL was reversed when stimulation index (SI) replaced the delta cpm estimate. Mycostatin (MYC) inhibited the blastogenic response of PBL control cultures, whereas its effect on LNL control cultures varied. The interpretation of the effect of MYC on PPD-stimulated cultures was dependent on the use of the delta cpm or SI estimates. The interpretation of LT experiments is therefore highly dependent on whether delta cpm or SI is used for expression of results. Analysis of effects on control and stimulated cultures should precede the addition of 2-ME or MYC to cultures for LT.

Kinetics and dose calculations of ampicillin and gentamicin given as continuous intravenous infusion during parenteral nutrition in 88 newborn infants.

Ampicillin and gentamicin were administered continuously intravenously to 88 newborn infants using individually calculated dosages. For infants with a mean value of plasma clearance of the antibiotics, it was calculated that the serum ampicillin and gentamicin concentrations would be between 35-55 and 3-5 micrograms/ml, respectively, using the dosages for intermittent treatment. These dosages are therefore recommended as fixed dosages for continuous intravenous infusion initiated by a bolus dosage. Serum gentamicin concentration should be assayed about three half-lives after start of infusion and the dosage adjusted for values outside 3-5 micrograms/ml.

Comparisons in sensitized and unsensitized guinea-pigs of tuberculin PPDs RT 23 and PPD-M by skin tests and lymphocyte stimulation tests. Effect of immunization time

The biological activities of tuberculin PPD RT 23 and the International Standard for Purified Protein Derivative of Mammalian Tuberculin (PPD-M) were compared in sensitized and unsensitized guinea-pigs by skin tests and lymphocyte stimulation (LS) tests. Estimates of relative potency (RP) from skin test results were dependent on the dose level, on the immunogen used, and, in guinea-pigs immunized with killed tubercle bacilli in oil, also on the immunization time. Relative potency estimates from LS results were dependent on the source of the lymphocytes and were different from estimates obtained from skin tests. Lymphocyte stimulation dose-response curves for the tuberculins were qualitatively different. In contrast to RT 23, PPD-M gave rise to non-specific skin reaction in unsensitized guinea-pigs. Both tuberculins were mitogenic to lymph node lymphocytes isolated from unsensitized guinea-pigs, PPD-M being the more mitogenic of the two tuberculins. The present results confirm that qualitatively different tuberculins cannot be unambiguously calibrated in identical terms and thus emphasize that the uncritical use of (international) standards should be avoided in tuberculin calibration.

Estimation of guinea pig antigen-specific and non-specific suppressor cell activity

A functional assay for the quantitative estimation of suppressor cell (SC) activity in guinea pigs has been developed. Cultures of antigen-stimulated peripheral blood lymphocytes (PBL) from sensitized guinea pigs develop SC activity. The suppression of proliferation can be demonstrated in antigen-stimulated autologous co-cultures of precultured and freshly isolated PBL. The extent of suppression is dependent on the preculture antigen concentration but not the preculture period and it consists, as demonstrated with PBL from doubly sensitized guinea pigs, of an antigen-specific and a non-specific component. The observed SC activities were not due to an alteration of the kinetics of the co-cultures. The estimates of suppression are highly dependent on corrections for the values of the control cultures. The present method may prove useful in immunological studies of mycobacterial infections in guinea pigs.