[Mercury hazard in pediatric practice]

Medical doctors, nurses, attendants, and patients at the UFRJ paediatric hospital were accidentally exposed to inorganic mercury. From July to December 1992, 228 mercury thermometers were broken in 6 paediatric wards. Contamination of the exposed group was assessed by a comparative cross sectional study in January 93. Mercury concentration was found to be two times higher in the urine of these professionals than in the control group (p<0.001).

Penicillin post-antibiotic effects on the biology of group A streptococci

Microbial growth in a Todd-Hewitt broth has been followed to determine the in-vitro post-antibiotic effects of penicillin in a Lancefield group A streptococcal strain. Bacteria were exposed for 2 h at 37 degrees C to 1 x MIC of penicillin. Following antibiotic removal, inactivation with penicillinase and regrowth in a drug-free broth, the duration of the effect was found to be 2.8 h. By studying the affinity of streptococci for xylene in the post-antibiotic phase we observed that the penicillin treatment had no effect on the cell surface hydrophobicity. The ability of the same streptococci to adhere to human buccal epithelial cells was greatly reduced. Streptococci exposed to penicillin produced much more deoxyribonuclease and hyaluronidase than control bacteria.

The effect of subminimal inhibitory concentrations of penicillin on growth rate and haemolysin activity of group G Streptococcus

The influence of the subminimal inhibitory concentrations (1/3 and 1/4 of the MIC) of penicillin on growth rate and on haemolysin production of a strain of group G Streptococcus was studied. It was shown that 1/3 of the MIC almost completely inhibited the bacterial growth, but it was not able to inhibit haemolysin activity in the culture supernate. The generation time of bacteria grown in 1/4 of the MIC was approximately twice longer than that of the control culture. In all cultures, the haemolysin, after being produced (or liberated), reached a peak and decreased to low levels, which could suggest that group G Streptococcus produces some end products of metabolism that are able to inhibit haemolysin activity.

Carnitine supplementation in diphtheria

We studied the effect of carnitine supplementation in patients with diphtheria. Six hundred and twenty five children of diphtheria received either DL-carnitine (100 mg/kg/day in two divided doses orally for four days), or no carnitine, in addition to the routine treatment for diphtheria. The patients receiving carnitine (n = 327) and controls (n = 298) were matched for age, sex, duration of symptoms, grade of toxemia and immunization status. Patients receiving carnitine showed a significant reduction in incidence of myocarditis as compared to controls (p = 0.001). Cases with myocarditis receiving carnitine therapy showed a significant reduction in mortality as compared to controls (p < 0.001). In view of a significant decline in incidence and mortality of myocarditis in cases of diphtheria, we recommended that all cases with diphtheria should receive carnitine supplementation.

Extracellular deoxyribonucleases of streptococci: a comparison of their occurrence and levels of production among beta-hemolytic strains of various serological groups

Production of extracellular deoxyribonuclease by 394 strains of beta hemolytic streptococci was examined employing a deoxyribonucleic acid-methyl green assay. Enzymatic activities were measured in supernatants of bacterial cultures. Of the strains tested, 316 (80%) produced the enzyme. Nuclease production was demonstrated in 100% of group A strains and in 85, 74 and 58% of groups B, C and G, respectively. Levels of nuclease activity were then evaluated statistically. The analysis of variance showed that group A strains produced more enzyme than did streptococci of groups B, C or G. Group B strains produced less nuclease than did isolates of groups C or G. There was no significant difference in the levels of nuclease produced by groups C and G or by the various serological types of group B streptococci. Human group C strains produced more enzyme than animal strains.

The protective effect of carnitine in human diphtheric myocarditis

Carnitine, an important cofactor in the transport of fatty acids to the interior of cell mitochondria, is depleted in myocardial tissue of guinea pigs submitted to diphtheric toxin administration. Mortality rates were reduced in these animals by supplying exogenous amounts of carnitine. The accumulation of fatty acids in the cytoplasm of human heart cells reported in cases of diphtheria suggests that carnitine might possibly be depleted in human myocardium as well. For the purpose of studying the effect of carnitine administration, 132 diphtheric patients were randomly divided into two groups, one of them (carnitine-treated group, n = 73) receiving DL-carnitine, 100 mg/kg/day during 4 days after admission, in addition to routine treatment, which was prescribed for this and the control group (n = 59). The presence of myocardial damage was evaluated by clinical, electrocardiographic, radiological, and enzymatic criteria. Carnitine administration resulted in decreased incidence of heart failure (P = 0.0475), of pacemaker implants (P = 0.0256), and of lethality indexes due to myocarditis (P = 0.013). We suggest that carnitine can play an important role in the treatment of diphtheric patients.

Hyaluronidase production by groups A, B, C, and G streptococci: a statistical analysis

Production of hyaluronidase by 147 strains of beta hemolytic streptococci was studied employing a sensitive dye-binding assay and levels of enzyme activity were evaluated statistically. The analysis of variance showed that group A strains isolated in Rio de Janeiro produced significantly smaller amounts of enzyme than group A strains from a Minneapolis (USA) collection or than groups B and G brazilian isolates. The t test revealed that M not typable nose/throat group A strains produced more hyaluronidase than skin isolates. The analysis of variance did not show a significant difference in the enzyme production between M typable and not typable brazilian strains of group A streptococci. High enzyme--producing strains were not restricted to a few serotypes of group B streptococci.