A simple blood agar plate medium for demonstration of the streptococcal serum opacity reaction

Blood agar plates for demonstration of the streptococcal serum opacity reaction were prepared by pouring into Petri discs four layers, one above the other, in the following sequence: 1. agar; 2. horse-sheep blood mixed with agar; 3. porcine serum in agarose; and 4. agarose. The strains to be tested were streaked with a loop on the plates and a control medium was prepared as described above, but without porcine serum. After incubation for 18 hours at 37 degrees C, the streptococci producing opacity factor showed greenish zones around the colonies or else no haemolysis at all on the plates containing porcine serum, in contrast to a clear betahaemolysis on the control plates. Opacity reaction negative steptococci showed the same clear beta-haemolysis on both plates. Concordant results were obtained by this method and a standard method for demonstration of opacity factor.

Binding of aggregated IgG to nephritogenic type 12 streptococci: influence of serum, C1 and C4

The uptake of aggregated IgG by type 12, M protein positive (M + ve) streptococci was high in the presence of fresh serum, while the uptake by type 12, M-ve, type 1 and type 2, M + ve or M-ve streptococci was inhibited. Serum heated to 56 degrees C for 30 min inhibited the uptake of aggregated IgG by all strains tested. Purified C1q or macromolecular C1 added to heat-treated serum restituted the uptake of aggregated IgG. It was shown that C1 and C4 in fresh serum influenced the uptake of aggregated IgG by streptococci, resulting in the distinct reaction patterns observed.

T-typing of group A streptococci from clinical specimens: restriction of the number if implied M types in each T-pattern by tests for opacity factor and nicotinamide adenine dinucleotide glycohydrolase

117 group A streptococci, consecutively isolated from routine throat swab cultures, were T-typed and further characterized according to their enzyme reactions. The results of typing with two different commercial kits of anti-T sera showed good agreement. 89 per cent of the strains were typable by either of these kits. 68 per cent of the strains were OF-positive and 95 per cent NADse-positive. With T-typing alone, 22 per cent of the strains showed agglutination patterns implying only one M type each. When considered together, the T-typing and enzyme reactions made it possible to implicate one M type only for each of 45 per cent of the strains. In a further 34 per cent of the strains, the possible M type of each strain was restricted to four types. However, these findings were hampered by the fact that the T patterns of a number of more seldom met group A streptococci have not been investigated adequately.

Staphylococcus aureus in the throat: A saprophyte or a pathogen?

144 industrial workers were investigated for the presence of Staphylococcus aureus in the upper respiratory tract because 53 of them had complained of chronic throat discomfort. Significantly more patients with subjective throat complaints harboured Staph. aureus in the nose (49.1%) and throat (32.1%) than patients without such symptoms (27.4% and 9.9%, respectively). No Staph. aureus were found in throat swab cultures from 21 randomly selected individuals working in a similar factory where no chronic throat discomfort was reported and only 2 throat carriers of Staph. aureus were found among 66 medical undergraduates investigated. The staphylocci belonged to several different phage type patterns and could not be recovered on sedimentation plates or from machines or products. In the light of these and other findings it was suggested that the staphylocci accentuated an already existing damage of the mucous membrane of the throat, but seemed not to be the primary cause of the discomfort.

Depletion of IgG in rabbit sera by absorption with some group A streptococci

Streptococci group A, type M 1 or M 56 were capable to deplete IgG in normal rabbit sera during absorption by means of a surface Fc receptor. One absorption with 8.0 mg (dry weight) M 1 streptococci or two absorptions with 71 mg M 56 streptococci removed all IgG in 0.2 ml rabbit serum diluted 1:10 (containing 1.5 mg IgG/ml). Antibodies to egg albumin and antibodies to sheep red cells were not demonstrable after absorption of 0.2 ml serum diluted 1:10 with 16.0 mg M 1 streptococci. These results are discussed in relation to some reports on immunologic cross-reactions between streptococci and mammalian tissues.

A study of complications in preterm deliveries after prolonged premature rupture of the membranes

The risk of infection for mother and baby after spontaneous rupture of the membranes was evaluated in a prospective study of 24 patients with ruptured membranes before the 36th week of pregnancy. The mean length of pregnancy after rupture was 10 days and 2 hours. Only patients harboring Group B streptococci or E. coli in the urogenital tract were treated with antibiotics (during delivery). With the exception of 1 woman, all patients harbored one or more pathogens in the urogenital tract. Four mothers were infected but all recovered. One of 26 infants died from infection. The study did not confirm any association between prolonged rupture of the membranes and the frequency of idiopathic respiratory distress syndrome, nor did it contradict attempts to actively prolong pregnancy after rupture of the membranes.

Quantitation of serum antibodies to surface antigens of Neisseria gonorrhoeae with radiolabeled protein A of Staphylococcus aureus

Antibodies in human sera against surface antigens of Neisseria gonorrhoeae were detected with use of 125I-labeled protein A from Staphylococcus aureus. Serum was allowed to react with a suspension of whole gonococci, and the antibodies attached to the bacteria were quantitated with protein A, which reacts with the Fc fragment of IgG. Tests with five human sera with a gonococcoal complement-fixation titer of greater than or equal to 1:30 revealed no difference between use of freshly isolated gonococci and use of strains subcultured daily on artificial medium for 10 years. Antibodies cross-reacting with N. gonorrhoeae and Neisseria meningitidis were found in human sera. The results of the test with labeled protein A varied with the serum titer of complement-fixing antibody to N. gonorrhoeae. Acute and convalescent sera from six of seven patients, including one with disseminated gonococcal infection, showed significantly larger differences in antibodies to N. gonorrhoeae than did sera of women without evidence of genital infection. Complement-fixation titers changed significantly in only three of the six patients.

Purification of immunolobulin G Fc-reactive factor from Streptococcus azgazardah

A factor from Streptococcus azgazardah (Lancefield's group C) capable of reacting with the Fc fragment of human IgG was partially purified and characterized. The bacteria were lysed by infection with phage, and the IgG Fc-reactive factor was purified from the crude lysate by affinity chromatography on a IgG-coupled Sepharose 4B column. The column was eluted with 3 M KSCN and the eluate gel-filtered on a Sephadex G 75 column. A 30-fold purification was obtained. The molecular weight of the IgG Fc-reactive factor was estimated to be 60,000. The factor was sensitive to trypsin treatment and to heating 95 degrees C, 10 min at pH 2.0. On polyacrylamide electrophoresis only one band was obtained. The trypsin-and heat-sensitivity, and the estimated molecular weight of the factor was similar to an IgG Fc-reactive factor preparation obtained from group A, type M 56 streptococci by heat treatment at 120 degrees C for 30 min.

Visualization of the binding of IgG myeloma proteins to some group A streptococci

The interaction between streptococci and human IgG, which does not involve the antibody combining sites, was visualized in the electron microscope by the use of human IgG myeloma proteins and ferritin labelled rabbit anti-human IgG antibodies. The streptococci were allowed to react with human IgG myeloma proteins and the human IgG was then marked by addition of ferritin labelled rabbit anti-human IgG antibodies; sections of streptocci studied in electron microscopy showed localization of the ferritin on the surface of the cell wall of all the streptococci of type M 1, M 3, M 12 and M 56 studied. Similar results were obtained if the ferritin labelled rabbit anti-human IgG antibodies alone were allowed to react with the streptococci. The uptake of ferritin labelled rabbit anti-human IgG antibodies could be inhibited by addition of normal rabbit serum.

Interaction of streptococci with the Fc fragment of IgG

The capacity of human IgG to interact with beta-haemolytic streptococci was studied in order to localize the site of interaction on the IgG molecule. The reactivity of different proteolytic fragments of IgG with streptococci group A, type M 1 and type M 56, group C and group G, was investigated by measuring their inhibitory effect on the uptake of 125I labelled IgG myeloma protein by the streptococci. Equivalent molar amounts of Fc fragment and undigested IgG inhibited the uptake of 125I labelled IgG myeloma protein equally well while only slight inhibition was obtained by F(ab')2 preparations. No reactivity was found with IgM, Fab or chymotrypsin produced fragment Fc', of IgG. The reactivity of IgG with the streptococci was localized to the Fc fragment. Since the Fc' fragment was non-reactive, the CH2 domain was probably carrying the IgG structures involved in the interaction with streptococci.

A specific radioimmunoassay for PGE2 using an antibody with high specificity and a sephadex LH-20 microcolumn for the separation of prostaglandins

Antiserum against PGE2 was raised in rabbits following immunization with prostaglandin-hen-gamma-globulin conjugate. The antiserum exhibited 14% cross reactivity with PGE1 and far less cross-reaction with heterologous prostaglandins. A microcolumn of Sephadex LH-20 was used for a partial, but sufficient separation of PGE2 from PGE1 and a complete separation from heterologous prostaglandins to ensure a specific RIA for PGE2. The precision of the method in the rage 10-500 picograms showed a coefficient of variation varying between 4 and 13%. The detection limit was 10 picograms corresponding to 15 pg/ml of PGE2 in serum. In order to demonstrate the validity of the method values obtained for non-diuretic rat renal venous serum were compared with those obtained using the isotope derivative method of Bojesen & Buckhave (1972) on the same samples. The concentrations of PGE2 obtained were 239 +/- 25 pg/ml and 250 +/- 58 pg/ml, respectively.

A multipurpose specimen-carrier for handling small biological objects through critical point drying

A specimen-carrier for safely handling, protecting and drying minute biological specimens down to 1.0 mum in size during the various steps of the critical point drying procedure is described. Free, unattached cells or subcellular fragments can be processed without loss and without risk of unintentional air-drying.

Indomethacin blockade of renal PGE-synthesis: effect on total renal and tubular function and plasma renin concentration in hydropenic rats and on their response to isotonic saline

The effects of indomethacin (I), a blocker of prostaglandin (PG)-synthetase, was studied in rats in an attempt to elucidate the physiological role of renal PGE. Plasma-I-concentrations of 13-14 mug/ml reduced renal venous plasma PGE-concentration significantly from 216 to 85 pg/ml within 45 min. Urine flow and solute excretion decreased by 42% and 20%, respectively, while urine osmolality increased 450 mOsm. Inulin clearance (CIN) and proximal reabsorption rate was unaffected, while renal plasma flow (RPF) decreased by 18%. Plasma renin concentration decreased slightly but significantly. An i.v. saline load equal to 1% b.wt. given to I-treated rats failed to elevate significantly either urine flow, solute excretion, CIN, RPF or proximal reabsorption rate, but plasma renin decreased further. The normal inverse relationship between plasma renin and proximal reabsorption rate was absent. The data are consistent with the concept that intrarenal PGE plays in adjustment of renal vascular resistance, and support the concept of a physiological role of intrarenal PGE in regulating salt and water excretion. The data do not support any major physiological role of PGE in regulating proximal tubular function.

New method for the serological grouping of Streptococci with specific antibodies adsorbed to protein A-containing staphylococci

A coagglutinating reagent has recently been developed and utilized in capsule typing of pneumococci. The reagent consists of stabilized staphylococci coated with specific antibody via the gamma globulin Fc-protein A reaction thereby orienting the antibody molecules with the antigen-reactive Fab parts outwards. Reagent staphylococci coated with antibodies directed against streptococcal group-specific antigens have been used in the present investigations. Overnight cultures of streptococci were treated with trypsin and then directly tested for coagglutination of selected reagent staphylococci on glass slides. In all, 179 strains of streptococci were analyzed by the method described. The results were compared with grouping by using Lancefield extracts in counter-immunoelectrophoresis and were shown to agree completely. The coagglutination method described proved to be accurate, rapid, and simple.