Grace Leidy

Treatment of type-specific hemophilus influenzae infections in infancy and childhood

Summary The clinical features of the following infections with type B H.influenzae are presented: meningitis, respiratory infection causing obstruction of the respiratory tract, and pneumonia complicated by empyema in infants under 1 year of age. A therapeutic program is outlined for each of these groups. The biology of H. influenzae is discussed for purposes of clarifying the principles which have been applied in treatment. Laboratory tests useful in the therapeutic program are presented. The results of the treatment advised in meningitis are analyzed from several points of view. Of the fifty patients reported, thirty-seven, or 74 per cent, recovered. The treatment of ten patients with obstructive infections of the respiratory tract is discussed.

Abnormal colonization of neonates in an intensive care unit: means of identifying neonates at risk of infection.

Summary: The current investigation was designed to select infants in the neonatal intensive care unit (ICU) at highest risk of infection. The data, derived from a prospective study of 223 neonates, indicate that neonates in an ICU develop their initial aerobic pharyngeal flora according to one of the three patterns shown in Table 1, one of which (low titer or no growth) is dependent on antibiotic therapy. Of particular importance is the finding that infants with normal flora (a-streptococci predominating) or cultures showing low titers (<104 colony-forming units (cfu)/ml) or no growth did not become infected. All infections occurred in the group of infants with abnormal pharyngeal colonization (18 infections in 115 abnormally colonized infants): with a single exception the infecting organism showed the cultural characteristics of the colonizing organism. Consequently one can pinpoint the relatively small number of infants at particular risk of infection and predict what the infecting organism will be if infection occurs.Speculation: These findings indicate indirectly that normal bacterial flora provides a significant host defense mechanism against infection. It seems reasonable that artificial development of “normal” flora by implantation of key constituents (e.g., α-streptococci) in the pharynx should increase the resistance of abnormally colonized high risk infants to infection.

The present status of treatment for influenzal meningitis

Abstract A larger experience and more time for long term evaluation of physical and mental development are needed before final statements can be made concerning the results of treatment of H. influenzae infections. Certain facts are evident, however. In patients in whom the infection is mild or moderately severe, according to the criteria previously described, either streptomycin alone or sulfadiazine in conjunction with specific rabbit antiserum can be expected to cure 100 per cent of them. A small fraction can be cured by sulfadiazine alone. When manifestions of severe infection are present in patients in whom it is evident from the history that the onset of the meningitis can be dated within a few days, the results suggest that a choice may be made between two therapeutic programs, the combined action of sulfadiazine with either streptomycin or type b H. influenzae antiserum. Experience with the latter regimen is so extensive that one can predict complete recovery in virtually 100 per cent of these patients. The use of the former program, simultaneous use of sulfadiazine and streptomycin, is still too limited to recommend it with assurance in this group, though its success is anticipated. Patients whose infections have progressed to the severe state despite the use of sulfonamides cannot be considered suitable cases for treatment with sulfadiazine in conjunction with streptomycin; the presence of sulfadiazine resistant H. influenzae in significant numbers may prevent these agents from eliminating the meningeal infection. Moreover a longer period of study on the toxic effect of streptomycin on the central nervous system is necessary before it can be recommended as the treatment of choice for this group even if it proves to be equally effective. Those patients with severe meningitis and a history which suggests that uncontrolled meningitis has been present for a week or more or who show signs of chronic meningitis with or without manifestations of localized cerebral injury should receive sulfadiazine, streptomycin and specific rabbit antiserum simultaneously. The latter program can be expected to reduce the risk of failure to a minimum since it combines the action of three antibacterial agents which exert their destructive influences through three different mechanisms. Members of the population resistant to one can be attacked by another or both the others. The difficulty in determining the time of onset of meningitis in young infants under seven months of age, because of failure of these infants to exhibit signs of meningeal infection until several days after onset, together with the still high mortality rate in this group, have led us to recommend the use of sulfadiazine, streptomycin and specific rabbit serum initially for these infants. It is in this severest group that the addition of streptomycin to sulfadiazine and specific antiserum can be expected to reduce the 20 per cent mortality which resulted from the combined use of the last two agents. The use of streptomycin alone or in conjunction with sulfadiazine is justifiable only when laboratory facilities permit evaluation of severity of infection and progress of recovery. The need for bacteriologic methods which can detect small numbers of viable organisms and evaluate sensitivity of any culture grown from the spinal fluid, is of paramount importance.

Purification of the desoxypentose nucleic acid of Hemophilus influenzae having transforming activity

Abstract The purification of DNA preparations of Hemophilus influenzae , types b and c, endowed with transforming activity is described. The mild procedure makes use of electrophoretic separation of the DNA from contaminating PNA and polysaccharides. The final DNA preparations, free of detectable amounts of these contaminants and of proteins, were active in transformation in concentrations of less than 0.0004 μg. and 0.01 μg. DNA/ml. for types b and c, respectively.

Experimental investigations as a basis for treatment of type B hemophilus influenzae meningitis in infants and children

Summary Experimental results demonstrate that there is a close correlation between the mouse protective capacity of sulfonamides and their degree of inhibition in the test tube against type b H. influenzae. Sulfadiazine is vastly superior to sulfanilamide and definitely more effective than sulfapyridine. A simple in vitro test is described for estimating the susceptibility of a given strain to sulfadiazine within forty-eight hours of isolation. Sulfadiazine and type-specific rabbit antibody, when used singly,have been shown to possess approximately equal protective value against lethal type b H. influenzae mouse infections. However, regardless of the dose administered they fail to protect regularly when the inoculum exceeds 10,000 minimal lethal doses. Mice treated with both agents together quite regularly survive following the injection of 1,000,000 minimal lethal doses. It seems quite clear that in the treatment of patients with influenzal meningitis the risk of failure is reduced to a minimum by the use of both serum and sulfadiazine. However, if the infection is judged mild by clinical and laboratory criteria, initial treatment with chemotherapy alone is justified, provided the recommended precautions and guides are used and provided the strain shows average susceptibility to sulfadiazine.

Induction of heritable new type in type specific strains of H. influenzae.

Summary 1. Normal strains of types b and d H. influenzae have been directly transformed to new types of H. influenzae; type b was changed to types a, c and d, and type d into types a, b and c. 2. The rate of occurrence in type d populations of cells susceptible of transformation has been shown to be not significantly different from that found earlier in R cell populations derived from type d. Comparisons in the presence of more potent anti d antibody have been made subsequently between populations of Rd and type d for frequency of cells susceptible (initially or during growth for 24 hours) to transformation to type c. No real differences could be demonstrated when this more efficient selective agent was used.

Interspecific Transformation in Hemophilus; A Possible Index of Relationship Between H. Influenzae and H. aegyptius.∗

Summary On the premise that the degree of reactivity of donor DNA with the heredity determinants of the recipient cell is a reflection of the degree of homology of the genome of donor and recipient cells, it has been proposed that transformation may serve as a valid criterion for bacterial taxonomy. If the use of a single genetic marker, SM-resistance, provides a valid basis for comparison, H. aegyptius may be a member of the H. influenzae group.

Transformation Type Specificity of H. influenzae.

Summary The data provide another example of the control of the genetic constitution of microorganisms by specifically oriented desoxyribonucleic acids. An R strain, Rbl, derived from type b H. influenzae was endowed with properties of type b under the influence of a desoxyribonucleic acid isolated from type b H. influenzae. This same R strain, Rbl, was transformed to type c H. influenzae when grown in an appropriate environment in the presence of an unpurified transforming principle isolated from type c H. influenzae. Rbl has also been transformed to Sa and Sd. The transforming activity of desoxyribonucleic acid has been shown to be destroyed by a crystalline desoxyribonuclease supplied by Dr. Maclyn McCarty.

Further Evidence of a High Degree of Genetic Homology Between H. influenzae and H. aegyptius.

Summary DNA-mediated transformation to novobiocin resistance has been conferred in sensitive H. aegyptius populations. A comparison of the frequency of this event induced by DNA of heterologous source (resistant Rd H. influenzae) and by DNA of homologous source (resistant H. aegyptius) supports the earlier report(3) which suggested a high degree of genetic homology between H. aegyptius and H. influenzae. The data suggest that a genetic factor (s) inherent in the receptor population influences the level of novobiocin resistance conferred by a given DNA. The genetic factors controlling streptomycin and novobiocin resistance have been demonstrated to be linked in H. aegyptius.

Sensitivity of populations of clonal lines of HeLa cells to polioviruses.

Summary Propagation of HeLa cell populations from single clones isolated by the Puck technic provides cells which are more stable in growth potential and virus sensitivity than “farm” populations from which they were selected. Populations from 6 clones have been studied; 4 were of predominant cell type by microscopic examination (clones 1, 2, 3 and 6) and 2 differed from the predominant type (clones 4 and 5). Clone 5 was the most sensitive and clone 4 the most resistant to types 1 and 2 polio viruses. Although clone 5, as a generalization, maintained its characteristic morphology and sensitivity to poliovirus for 2 years, it was not possible to correlate morphology with sensitivity to the polioviruses. Selection and propagation of this most susceptible of the 6 clonal populations isolated provided a stable tool for studies of polioviruses. Since line 5 maintained its greater sensitivity for at least 2 years, a heritable factor (or factors) is probably responsible for the greater sensitivity.