Enzyme-linked immunosorbent assay for detection of immunoglobulin G and M antibodies to teichoic acid in intravascular staphylococcal disease

An enzyme-linked immunosorbent assay (ELISA) for detection of IgG and IgM antibodies to cell-wall teichoic acids of Staphylococcus aureus and three defined coagulase-negative staphylococci was tested using serum samples from 11 cases of intravascular coagulase-negative staphylococcal infections, 13 cases of Staphylococcus aureus endocarditis, and 24 patients with no evidence of infection. IgG antibody titers to all four teichoic acids in the 13 patients with Staphylococcus aureus endocarditis were significantly different from those in noninfected control patients (p less than 0.0001). In contrast, IgG antibody titers in serum from 11 cases of intravascular coagulase-negative staphylococcal infection were not significantly different from those in control sera. There were no differences in IgM antibody titers of the three groups. Although the ELISA was sensitive in detecting Staphylococcus aureus endocarditis, it was not reliable in the detection of intravascular coagulase-negative staphylococcal infections, even when tested with specific teichoic acid.

Antiserum agar method for identification of Smith type exopolysaccharides in clinical isolates of Staphylococcus aureus

We used an antiserum agar method to identify clinical Staphylococcus aureus strains producing an exopolysaccharide antigenically identical to the S. aureus Smith diffuse strain. S. aureus blood isolates were obtained from 137 patients, and three additional isolates were obtained from bone debridement. The 140 patients were clinically divided into the following groups: endocarditis (7 patients); pneumonia, empyema, or both (33 patients); intravascular device (34 patients); superficial or wound infection or both (35 patients); deep tissue infections (18 patients); and 6, unknown bacteremias (13 patients). Ninety (64.3%) of the total 140 S. aureus isolates were found to produce precipitin halos on the antiserum agar. The percentage was greatest in the isolates from the endocarditis group (100%) and least in deep tissue infections (55.5%). The presence of clinical S. aureus strains producing exopolysaccharides antigenically identical to the Smith diffuse strain exopolysaccharide appears to be a common phenomenon.

Detection of encapsulation in Staphylococcus aureus by use of antiserum agar

We examined an antiserum agar method to study its reliability in screening Staphylococcus aureus strains for capsule production. The encapsulated S. aureus Smith diffuse strain was compared with its nonencapsulated variant, Smith compact, in CCY medium containing 0.5% NaCl and 5.0% Smith diffuse rabbit antiserum. A halo was visible surrounding colonies of the Smith diffuse strain but not the Smith compact strain. On this same medium, the protein A-producing Cowan I strain possessed a halo that was visible on photographs. Single high-salt medium is known to inhibit protein A production, halo formation by the strains was also compared in 7.5% NaCl medium. The halo surrounding the Cowan I strain was not present when the salt content of the medium was increased. In contrast, the halo surrounding the Smith diffuse strain persisted in the 7.5% NaCl medium. By use of this medium, the antiserum agar technique may be valuable for the identification of encapsulated staphylococci without appreciable interference from protein A.

Detection of anti-teichoic acid immunoglobulin G antibodies in experimental Staphylococcus epidermidis endocarditis

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of rabbit immunoglobulin G (IgG) antibodies to purified cell wall teichoic acids from the Staphylococcus aureus Lafferty strain and three strains of coagulase-negative staphylococci. Significant immunological cross-reactivity occurred only between the teichoic acid of S. aureus and one coagulase-negative preparation. The ELISA was used to determine the serum IgG response to Staphylococcus epidermidis in a rabbit model of aortic valve endocarditis. Blood samples were drawn before inoculation and then every 5 days until death or sacrifice at 32 to 35 days postinoculation. Valve vegetations were culture positive at autopsy in 16 (59%) of the 27 catheterized rabbits. Antibody titers in this culture-positive group and the culture-negative group began to rise as early as day 6. Although both groups demonstrated an antibody response, the culture-positive group attained a significantly higher titer on days 26 and 31. Antibodies also rose in a control group of rabbits without a heart catheter but which were inoculated with bacteria. Again, the antibody titer was significantly less than that for the culture-positive group. This ELISA may be useful for the diagnosis of coagulase-negative staphylococcal infections in humans.

Evaluation of a commercial counterimmunoelectrophoresis kit for detection of Staphylococcus aureus teichoic acid antibodies

A commercial kit from Diagnostica, Inc., Miami Fla., was studied for its ability to detect antibodies to the teichoic acids of Staphylococcus aureus. A comparative study of the Diagnostica counterimmunoelectrophoresis (CIE) system and our gel double-diffusion method was undertaken with 156 serum samples from 142 patients. Included were 25 cases of staphylococcal and non-staphylococcal endocarditis, 30 cases of S. aureus bacteremia, 19 cases of nonbacteremic S. aureus infection, 39 cases of hospitalized patients without a staphylococcal infection, and 29 normal controls. Agreement between methodologies was attained in 138 (88.5%) of the 156 samples tested and in 127 (89.4%) of the 142 patients. Of 13 patients with culture-proven S. aureus endocarditis, significant antibody titers were found in all patients (100%) by CIE and in 12 patients (92.3%) by double diffusion. No significant titers were found in normal sera by CIE, but four sera were positive by double diffusion. Of 80 sera from patients with no evidence of S. aureus infection, 4 (5.0%) were positive by CIE and 7 (8.8%) were positive by double diffusion. The Diagnostica CIE kit appears to provide a suitable means for the detection of deep-seated S. aureus infections.

Gallium-67 scintigraphy in abdominal anaerobic abscesses

Three cases of anaerobic abdominal abscesses showing poor uptake on Ga-67 scintiscans are presented. The significance of this and possible mechanisms for it are discussed.

The effects of energy and carbohydrate restriction in patients with chronic diabetes mellitus

Thirty-five freshly presenting, diabetic patients received 5 hour, 100 g oral glucose tolerance tests when first seen and after a period of carbohydrate and energy restriction. After treatment, the significant improvement in glucose tolerance was accompanied by increased insulin secretion and lower concentrations of blood ketone bodies, lactate, glycerol, FFA, triglycerides, cholesterol and pre-beta lipoprotein. There were no significant changes in serum growth hormone or blood pyruvate concentrations. Improvement in glucose tolerance was greater in patients who were obese (greater than 115% of desirable body weight for height) on presentation and was related to the improvement in insulin secretion and the diminished lipolysis. An hypothesis to explain the changes in insulin secretion is prosposed. Eleven out of the 35 patients showed sufficient improvement in glucose tolerance to require no treatment other than diet.

Is the growth-hormone response to insulin due to hypoglycaemia, hyperinsulinaemia or a fall in plasma free fatty acids?

Seven normal male volunteers were given a 2 h intravenous infusion of insulin (2 mu kg-1 min-1). During the first hour, in which nomoglycaemia was maintained by glucose infusion, no detectable increase in growth hormone (GH) secretion occurred. When controlled symptomatic hypoglycaemia was produced during the second hour of the insulin infusion a brisk rise in plasma GH concentration was observed in all the subjects studied. Since it was possible that the falls in the concentration of plasma free fatty acids (FFA) occurring during infusion of insulin also acted as a stimulus to GH release the study was repeated in four subjects but normoglycaemia was maintained throughout the entire 2 h period of insulin infusion. In these experiments there was no rise in plasma GH concentration although a similar fall in plasma FFA was produced. These results clearly indicate that hypoglycaemia per se was the important stimulus to GH secretion and not hyperinsulinaemia or a lowering of plasma FFA. Furthermore there appeared to be a threshold hypoglycaemic stimulus to GH secretion. In no subject was a rise in plasma GH seen without a fall in plasma glucose greater than 1.4 mmol/l. Prolonged mild hypoglycaemia did not stimulate GH secretion.

Evaluation in clinical practice of Dextrostix and the Eyetone Reflectance Meter

Venous blood glucose concentration measured by Dextrostix-Eyetone Reflectance Meter method were compared with conventional enzymatic measurements of plasma glucose in the same 373 blood samples over the range of 0.55-22.2 mmol/l (10-400 mg/100 ml). Agreement between the two methods was good up to 5.5 mmol/l (100 mg/100 ml) but above 11.1 mmol/l (200 mg/100 ml) the Dextrostix-Eyetone method gave higher results for glucose concentration. The Dextrostix-Eyetone method is a reliable means of confirming or refuting the clinical diagnosis of hypoglycaemia and is useful in the day-to-day management of diabetes mellitus in situations where insulin dosage requirements are varying and where access to clinical laboratory facilities are not readily available.

Control of blood glucose during labour in diabetic women with combined glucose and low-dose insulin infusion

During 15 labours in diabetic women blood glucose concentrations were controlled with simultaneous infusion of insulin and glucose. The mean insulin infusion rate was between 1 and 2 U/h. No infant showed evidence of neonatal hypoglycaemia. The procedure is simple to use and may be carried out in any labour ward.

Acromegaly caused by pulmonary carcinoid tumours

Two patients are described whose acromegaly was cured by removal of a bronchial carcinoid tumour. One had an enlarged pituitary fossa and evidence is presented that in this patient the tumour was not secreting growth hormone. The evidence available suggests that the tumour was producing a growth hormone releasing substance. It is suggested that some cases of the pluriglandular syndrome may be secondary to small bronchial carcinoid tumours that produce substances as yet unidentified, that stimulate the growth and hyperactivity of other endocrine tissue.

Horner's syndrome and headache due to carotid artery disease

Horner's syndrome was accompanied by ipsilateral pain in the head, face, or neck in eight patients. In all cases angiography showed narrowing of the internal carotid artery in a pattern compatible with dissection within the arterial wall. In one patient in whom this diagnosis was substantiated by surgical exploration biopsy of the arterial wall showed changes typical of cystic medial necrosis. It is suggested that this clinical presentation constitutes a distinct syndrome.

Metabolic responses to monocomponent human insulin infusions in normal subjects and patients with liver and endocrine disease

Hypoglycaemic and growth hormone responses were studied at different steady-state plasma insulin concentrations during a graded infusion of monocomponent human insulin. The control group consisted of ten volunteer subjects. The other groups studied included women taking oral contraceptives and patients with obesity, thyrotoxicosis, myxoedema, acromegaly, diabetes mellitus (moderate and severe) and liver disease. The hypoglycaemic response was measured in two ways: (i) the percentage reduction in plasma glucose below basal, and (ii) the rate of fall of plasma glucose (Kg-%/min). Insulin sensitivity was greatest in the normal subjects and in the other groups decreased in the order thyrotoxicosis greater than oral contraceptive greater than obesity greater than myxoedema greater than acromegaly greater than liver disease. Insulin sensitivity was difficult to assess in the diabetic patients because basal plasma glucose concentrations were elevated. At any given insulin concentration, the diabetics metabolized approximately the same amount of glucose as the normal subjects but the fact that this rate of glucose turnover occurred at higher plasma glucose concentrations probably indicated insulin resistance. Within each group Kg at each dose level of insulin correlated with the steady state plasma insulin concentration during the same infusion period. Diminishing sensitivity to insulin was reflected in an increasing fasting plasma insulin and insulin/glucose ratio except in patients with diabetes. GH responses to insulin infusion in normal subjects reflected the pattern of fall of plasma glucose. In the diabetic patients GH secretion appeared to be related to the infusion of insulin and occurred before plasma glucose had fallen to hypoglycaemic levels. GH secretory patterns were within normal limits in women taking oral contraceptives and in seven of eleven patients with liver disease but were impaired in three of seven patients with thyrotoxicosis and four of five patients with myxoedema. Four obese patients had a markedly delayed but eventually normal GH response.

Treatment of diabetic coma with continuous low-dose infusion of insulin

Thirty-eight patients in diabetic coma from four different centres were treated with a continuous low-dose intravenous infusion of insulin at an average dose of 7.2 IU/hr. All patients recovered rapidly except for one profoundly shocked patient who died. The mean fall in plasma glucose was 58% four hours after the start of insulin. Blood ketone bodies and plasma free fatty acids showed a similar response. There was no significant difference in plasma glucose response according to severity of acidosis or previous treatment with insulin. Hypokalaemia was uncommon. In the treatment of diabetic coma this technique has proved simple, safe, and effective.