Metabisulfite sensitivity: case report and literature review

Sulfiting agents have recently been identified as food and drug additives responsible for adverse reactions. These reactions are not rare and may result in life-threatening asthma and anaphylaxis. We report a 34-year-old female with intractable asthma and urticaria. Sensitivity to sulfites was suspected based on exacerbation after restaurant meals and metaproterenol 5% inhalant solution. Bronchial provocation challenge resulted in a 28% decrease in FEV1 and a 34% decrease in FEF25-75 at the 0.01 mg/ml dose. Thirty-two cases of sulfite sensitivity reported in the literature are reviewed. Foods and drugs containing sulfites are listed. The pathogenic mechanism is unknown. The FDA allows the addition of sulfites to foods and drugs without disclosure. Only recently has this potential hazard been recognized. The FDA is considering a labeling requirement on drugs that do contain sulfites.

Drug interactions: theory versus practice

Cimetidine inhibition of P-450 oxidative metabolism results in interactions with many drugs, leading to clinically significant drug toxicity. A one-year survey of inpatient prescribing practices revealed a 32.6 percent incidence of concomitant cimetidine and interacting drug use. Retrospective chart review showed statistically significant increased toxic drug plasma levels in patients receiving theophylline and cimetidine, and a strong trend to increased rates of drug toxicity in phenytoin-cimetidine treated patients. Ranitidine appears to be a superior choice in patients receiving drugs metabolized by P-450 oxidation. When cimetidine and known interacting drugs are prescribed together, more frequent assessment of blood levels of the affected drug will be required, increasing substantially the cost to patients. Drug interactions of clinical significance occurring due to altered absorption because of effects of H2-receptor antagonists on gastric secretion are reviewed.

Psychological and physiological effects of relaxation and nitrous oxide training

Training in progressive muscle relaxation can improve psychophysiological response to stress but is often time-consuming and may prove ineffective for some individuals. Nitrous Oxide (N2O)may offer an effective adjunct or alternative to training. This study evaluated the relative efficacy of these procedures. Subjects were randomly assigned to one of four treatment conditions: relaxation-only, N2O only, relaxation with N2O, and room air-control. The relaxation procedure was modeled on color videotape. Nitrous oxide was administered from a balloon. In addition to various psychological measures, treatment effects were measured for skin temperature, heart rate, systolic blood pressure, and two measures of diastolic blood pressure. Subjective reports of tension were also recorded. There was a significant multivariate difference between treatment groups. The relaxation-only procedure was generally superior to the others on most dependent measures. Subjects receiving N2O appear to have experienced an improvement in mood. Paradoxically, the initially more relaxed subjects seemed to derive the greater benefit from the inhalation of N2O. The use of videotape-modeled relaxation procedures is discussed.

A collaborative effort to study methods of teaching physical examination skills

A collaborative study was conducted between two medical schools to evaluate critically the teaching of physical examination skills to first-year medical students, assess the effect of different instructional methods on student performance, and improve teaching programs at both schools. Students at the two schools were videotaped performing a physical examination on a paid model at the completion of their physical diagnosis courses. The videotapes were sent to a third school for independent evaluation based on criteria agreed upon by all three schools. Students participating in a highly structured course and utilizing a very specific behavioral checklist as both a teaching and evaluating instrument tended to perform more complete physical examinations than students from a less structured course and employing a more generalized checklist. Both medical schools benefited from participation in the study.

Induction of L-forms of Haemophilus influenzae in vitro

The induction of L-forms of Haemophilus influenzae by penicillin, amoxycillin and glycine has been studies in vitro on a nutrient-agar medium. The minimal inducing concentrations of the antibiotics were generally the same as their minimal inhibitory concentrations, but the addition of a sub-inducing concentration of glycine lowered the minimal inducing concentration of penicillin. Preliminary observations have shown that L-forms are induced by penicillin or amoxycillin on a medium in which mucoid sputum forms the sole source of nutrients, and that they remain viable for at least 48 h in the absence of added osmotic stabiliser. The minimal inducing concentration on "sputum agar" is within the range of concentrations measured in sputum from patients receiving amoxycillin therapy. The implications of these observations in relation to bactericidal therapy of haemophilus infections of the respiratory tract are discussed.

Osmotically stable L forms of Haemophilus influenzae and their significance in testing sensitivity to penicillins

The sensitivity of Haemophilus influenzae to penicillins in vitro, determined either by serial antibiotic dilution in broth or by the disc method on agar, is apparently profoundly influenced by inoculum size if the results are read by macroscopic inspection. Microscopic inspection of the growth, however, reveals that the turbidity in heavily inoculated broth containing concentrations higher than the minimal inhibitory concentration is the product of L forms which have failed to succumb to osmotic lysis. Similarly, minute colonies appearing in the ;inhibition zone' of disc tests are composed of L forms. In both broth and agar tests reduction of the osmolality of the medium from 340 to 144 mOsm per kg failed to bring about lysis of organisms exposed either to ampicillin or amoxycillin. The significance of this remarkable osmotic stability of haemophilus L forms is discussed in relation both to testing of sensitivity of this organism to penicillins and to persistence of chronic haemophilus infections of the lower respiratory tract.

An improved test for Haemophilus influenzae precipitins in the serum of patients with chronic respiratory disease

The detection of antibacterial precipitins in the serum of patients with chronic lower respiratory infections has been shown to be of great value in the assessment of pathogenicity of the corresponding bacterial species in the sputum. The test used hitherto, however, is time-consuming and cumbersome owing to the need to distinguish, by immunoelectrophoresis, between antibodies specific to the organism in question and those which react with antigens common to various Gram-negative species. A method has now been devised for the preparation of an extract of Haemophilus influenzae containing species-specific antigens only. Use of this extract obviates the need for immuno-electrophoresis and improves the sensitivity of the test.

Bacterial infection in cystic fibrosis

Tests for precipitins against Staph. aureus, H. influenzae, Ps. aeruginosa, Strep. pneumoniae, and Kleb. pneumoniae were carried out on the serum of 195 patients with cystic fibrosis, whose ages ranged from 3 weeks to 31 years. Sputum was obtained for culture from 96 patients over 5 years old. Precipitins against Ps. aeruginosa were more common than those against any other organism, including Staph. aureus, in the 0- to 5- and 6- to 10- year-old groups, while mucoid Ps. aeruginosa was the commonest pathogen isolated from the sputum of the 6- to 10-year-old children. These findings suggest that Ps. aeruginosa is the commonest bronchial pathogen in the younger patients and seem to conflict with the belief that Staph. aureus is always the initial pathogen in cystic fibrosis. Indeed, in 2 patients Ps. aeruginosa was proved to be the initial pathogen, and it is probable that patients with cystic fibrosis are susceptible from birth to bronchial infection by any pathogen with which they come in contact. The prevalence of pseudomonas infection, in contrast to that for staphylococcal or haemophilus infections, fell strikingly in the oldest patients, and this may reflect the failure of many patients with pseudomonas infections to survive into adult life.

Resistance of Haemophilus influenzae to trimethoprim

Out of 210 isolates of Haemophilus influenzae obtained from the sputum of 63 patients with chronic respiratory infections 109 (52%) were resistant to trimethoprim-sulphamethoxazole by the disc test. The minimal inhibitory concentrations of trimethoprim for 17 out of 18 strains recorded as resistant were 10 mug/ml or higher. Resistant strains were isolated from time to time from 32 (82%) out of 39 patients known to have been treated with trimethoprim-sulphamethoxazole, compared with only 1 (12.5%) out of 8 patients known not to have been treated with this drug combination. Resistant strains were isolated most frequently from patients who had received long-term treatment. Since sulphamethoxazole penetrates from the blood into the bronchial secretions less readily than does trimethoprim it seems likely that the ratio of the two drugs in the bronchial tree is far from ideal. This may be an important factor in the use of these drugs for chest infections.