Biomedical subjects
Publications and source records attributed to U Forsum.
The relationship between urinary immunoglobulin levels and coating of a panel of bacteria by these immunoglobulins has been investigated. The results indicate that elevated urinary immunoglobulin levels are a distinct hazard in interpreting tests for antibody-coated bacteria as indicating upper or lower urinary tract infections.
Ia antigens, known to be expressed preferentially on cells of the immune system, have been shown to be present on cells in the cornea. By immunofluorescence studies, it was shown that a specific rabbit anti-Ia antigen serum stained cells in the corneal epithelium. The stained cells were well integrated into the corneal epithelial architecture and displayed short dendritic processes. Their location in the cornea and corneal limbus and their morphological appearance make it reasonable to suggest that the Ia antigen-expressing cells of the cornea are equivalents of the Ia antigen-bearing Langerhans' cells of the epidermis.
Smears of urethral and cervical discharge for direct microscopical examination of gonococci were stained with acridine orange and methylene blue and the findings compared with culture of direct inoculated plates. These two staining methods yielded similar results. Acridine orange staining seems a valuable alternative due to its sharp image contrast.
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A test for antidoby-coated bacteria in the urine for the diagnosis of the anatomical level of urinary tract infection was evaluated in an unselected series of patients with urinary tract infection as a complication of other diseases of the uro-genital tract. Of 19 patients with cancer of the bladder, prostata and the kidney who had clinical signs of lower tract infection, 14 had antibody-coated bacteria in the urine. Among adult patients without cancer of the urinary tract but a clearcut history of upper tract infection, 17 had antibody-coated bacteria, while 8 had not. Six patients also without history of cancer, with clearcut lower tract infection, had antibody-coated bacteria; 38 had not. The results indicate that cancer of the urinary tract seems to influence the correct establishing of level of infection by this method. In patients with diseases of the urinary tract in additional to infection, antibody coating by bacteria in the urine must be interpreted with caution.
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Recent studies indicate that tonsillar gonococcal infection or colonization is fairly common. Carriage rates of about 8% have been found. These studies also indicate that oro-genital contacts are common. Since very little is known about the amount of oral microbiota transmitted to the genitals, we have studied the occurrence of oral streptococci and Neisseria species in urethra and cervix. Among 128 patients attending an STD-clinic we found 10 carriers of oral streptococci, one Streptococcus mitior, four Streptococcus sanguis, one Streptococcus mutans and four Streptococcus salivarius and case of urethritis due to Neisseria menigitidis. Seventy-three of the patients had recently had their genitals exposed to the oral flora of their partners. Despite the heavy contamination with oral microbiota that can be assumed to occur in these cases, there seems to be no colonization of the genitals with oral microbiota.
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Beta-2-microglobulin (beta2-m) is associated with the epidermis in normal and pathological human skin and gives an immunofluorescence pattern similar to that of pemphigus antibodies and concanavalin A (Con-A). Inhibition experiments indicate, however, that the binding site of anti-beta2-m is not identical with that of pemphigus antibodies or Con-A. It is suggested that beta2-m might be an epidermal cell surface marker useful for the study of antigens associated with the epidermal cell surface.
Differences in the cell surface of malignant cells, as compared with normal cells, are believed to be characteristic of many features of tumor cell behaviour. We have obtained evidence suggesting that solid and superficial basal cell carcinomas lack immuno-reactive beta-2-microglobulin (beta-2-m) on the cell surface, in contrast to normal epidermis and that of various non-malignant dermatoses, including basal cell papillomas.
The test for antibody-coated bacteria in urine for the diagnosis of the anatomical level of urinary tract infections was evaluated in children with UTI. The ability of the test to differentiate between an upper and lower infection is influenced by the antiglobulin preparation used, since too sensitive an antiglobulin probably detects nonspecifically bound antibodies. Staphylococcal protein A seems to be well suited for use as an antiglobulin in this test. Using staphylococcal protein A all children with X-ray findings suggesting renal damage had antibody-coated bacteria in the urine, however, nine infants and 5 children and clinical symptoms of pyelonephritis had a negative test. Of 28 children with clinical symptoms of cystitis only one had a positive test. Of 50 children with asymptomatic bacteriuria 9 had antibody-coated bacteria in the urine; 41 had not. The findings indicate that the method might be useful in establishing the anatomical level of urinary tract infection and might also be useful for screening children with asymptomatic bacteriuria who risk developing kidney infections.
During the months October to December of the years 1971-1974 the incidence of beta-haemolytic streptococci of the Lancefield groups, A, B, C and G from patients in the County of Uppsala was studied. The proportion of culture positive patients increased during the period studied from 7.2% to 13.7%. The increase was not only due to group A. In cultures from the respiratory tract the finding of group A streptococci increased from 4.1% to 10.7% and group C from 0.1% to 1.6%, while group B and G streptococci remained constant. In cultures from wound infections the percentage of patients culture positive for group A streptococci increased from 6.2% to 8.7%, group B from 0.8% to 1.9%, and group G from 0.5% to 0.9%, while group C remained constant. During the same months of the years 1972 to 1974 the frequency of sera with an antistreptolysin O titre of more than 1 000 U/ml increased from 0.6% t0 2.3% in the same region. A clinical study of scarlet fever and pharyngotonsillitis at the Department of Infectious Diseases showed a similar trend concerning group A streptococcal infections. These results stress the great importance of group A beta-haemolytic streptocci in human infections and indicate that the recent interest in non-group A infections should be continued.
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Defined IF techniques have been used in our laboratories for the past 15 years for diagnosing meningococcal and gonococcal infections. Conjugates against these bacteria give desired specific staining (DSS) but also undersired specific staining (USS) due to cross-reacting antigens. USS is controlled by absorption. Nonspecific staining (NSS) of protein A-containing S. aureus caused by the reaction with the Fc part of the IgG molecule is blocked by adding RB 200-labeled antiS. aureus globulins to diluted FITC conjugates against gonococci or menigococci. Nss is also avoided by using FITC-labeled F(ab')2 fragments of IgG. By optimal labeling and separation of unlabeled FITC and heavily labeled molecules on Sephadex G-25 at low ionic strength and low pH, nonspecific reactions with tissues are reduced to a minimum. Defined IF can be utilized for diagnosing pathogenic Neisseria by examination of smears prepared from clinical specimens, as confirmative tests of oxidase-positive colonies, and for demonstrating these bacteria in tissue efflorescences and tissue biopsies. It is stressed that this technique should always be used in conjunction with conventional methods.
An immunofluorescence method for the identification of groups A, B, C, E, F, and G beta-haemolytic streptococci has been developed, using FITC-labelled F(ab')2 fragments of IgG with optimal staining characteristics. The method is useful for the rapid confirmation of beta-haemolytic streptococci in cultures; in a blind comparison with Lancefield grouping, there was a 97 per cent agreement.