Winifred Redman

Evidence Suggesting Importance of Role of Interbacterial Inhibition in Maintaining Balance of Normal Flora

Abstract Evidence presented in support of the hypothesis that interrelationships among organisms in the pharynx provide one of the mechanisms that maintain the bacterial status quo. Many organisms ...

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.

Production of poliomyelitis virus with combined antigenic characteristics of type I and type II

Abstract Evidence is presented indicating that a “combined” poliomyelitis particle which can be neutralized by type I as well as by type II antiserum has been produced in tissue cultures after simultaneous infection of monkey kidney cells with type I and type II poliomyelitis viruses. Serial passage of the “combined particles” suggests that they are capable of reproducing as such but are not stable.

Infectious Ribonucleic Acid Derived from Enteroviruses.

Summary 1) RNA-containing fractions have been prepared from crude tissue culture virus suspensions of 6 varieties of enterovirus by the method of Gierer and Schramm. Each RNA preparation has produced plaques on human cell monolayers. The plaque-forming agent is completely inactivated by RNAase but not by DNAase. RNA is, therefore, an essential component for the infectivity of the preparation. 2) The plaques formed by RNA fraction contain intact virus from which RNA is prepared. The RNA directs the cell to replicate not only the specific RNA but also a new highly specific protein needed for synthesis of intact original virus.

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.

PHARYNGEAL IMPLANTATION OF ALPHA HEMOLYTIC STREPTOCOCCI (STREP) IN NEONATES IN AN ICU

Pharyngeal implantation of a carefully selected strain of α-strep (#215) was attempted in 14 neonates with high titer abnormal colonization of the pharynx with potential pathogens (e.g., conforms, pseudomonads, staphylocccci) to convert the flora to “normal” (m-strep predominant). Serial semi-quantitative culture samples from 346 neonates in an ICU showed strong positive correlation between high titer abnormal colonization of the pharynx and infection. To date, no demonstrable systemic infection occurred in those infants with “normal” pharyngeal flora. All but one of the 14 infants received a single dose, approxinately 106 colony forming units (CFU), of strain 215. The youngest was 8 and the oldest 64 days old when given the strain. The pharyngeal flora of 10 of the infants became “normal” within 2-3 days. In 5, implantation is considered responsible for the change because only the implant type was recovered initially. In the other 5 infants a low (4% or less) to moderate (5-15%) proportion of their strep initially resembled the implant. The strain was not recovered from 4 infants. Included in the 4 is the first infant given the strain who received too low an inoculum (102-204 CFU). Another was given cholamphenicol within 24 hrs of the implant. The data show 1) Implantation can be carried cut in high titer abnormally colonized infants 2) “Normal” flora is attained in 2-3 days 3) The implant strain can be identified in mixed strep populations 4) No adverse effect of the implant strain has been noted.

ABNORMAL COLONIZATION AND INFECTION IN NEONATES Kotherine Sprunr

The incidence of infection and its relationship to bacterial colonization of the pharynx of infants in a neonatal ICU has been investigated. Pharyngeal bacterial flora were frequently monitored on a semi-quanfitive basis in 62 infants with RDS and 70 concurrent broadly matched controls. All infections occurred in infants with high abnormal colonization and were due to the type of bacterium producing the high colonization. Early high abnormal colonization occurred more frequently in RDS infants (42%) than in controls (27%); this high incidence was independent of antibiotic treatment. 5 of 9 abnormally colonized RDS infants without therapy had sepsis compared to only 1 of 5 control infants (urinary tract infection). Staphylococcus epidermidis and Gram negative enteric bacilli were the most frequent causes of high colonization; most infections were due to the enteric bacilli. Infection rates were similar in the two groups receiving antibiotics (RDS 4/41, controls 3/50) but differed when no antibiotics were given (RDS 6/21, controls 1/20). We recommend that all ICU infants, particularly those with RDS, be followed closely with frequent throat cultures to determine those with added risk of infection. Abnormally colonized infants should be treated on minimal indication as directed by the antibiotic sensitivity of the colonizing organism.

Antistaphylococcal Substance(s) from a Pharyngeal Organism

In our study of the ecology and significance of the normal bacterial flora of the human pharynx we have noted in the cultures of 4 individuals an organism which elaborates a substance(s) producing wide clear zones in agar overlays containing staphylococci. Growth of the organism, a slow growing coccus (or coccobacillus), is inhibited in vitro by some ingredients of normal flora. The organism, which is sensitive to commonly used antibiotics such as penicillin, coexists in the pharynx with its inhibitors and with staphylococci and may play a role in maintaining the normal interrelationships between species. The antistaphylococcal substance(s) produced by it is filterable, heat stable and has a limited antibacterial spectrum. All staphylococci tested, including those resistant to methicillin, are higher sensitive (1/400 to 1/800 dilution of an autclaved broth supernatant incorporated in blood agar). Using the same preparation, enterococci are moderately sensitive (1/50 dil) and all other species examined are either weakly sensitive (1/10–1/25 dil) (Group B and C β-hemolytic streptococci, N. catarrahalis and some viridans streptococci) or resistant (Group A, β-streptococci, some viridans streptococci, other Neisseria and all gram-negative bacilli tested including H. influenzae). The antibacterial agent is bactericidal for staphylococci; persisters remain sensitive. No resistant mutants have been selected. The antibacterial capacity for the staphylococcus is not destroyed by exposure to trypsin, chymotrypsin or peptidase, or a range of pH from 9.4 to 4.3. This organism may play a significant ecological role in the pharynx; its antistaphylococcal substance is potentially useful.

A Method for the Quantitative Measurement of Agglutinin Nitrogen in Antisera to Hemophilus pertussis, Phase I.

A method for the measurement, in weight units, of the agglutinin nitrogen in antisera to Hemophilus pertussis, Phase I, is described. The procedure and techniques are essentially the same as those first published by Heidelberger and Kabat for the measurement of agglutinin nitrogen in antipneumococcal sera. However, it was found that unusually large amounts of bacterial nitrogen were required to absorb pertussis agglutinins completely, even when the antibodycontent of the antisera was low. The accuracy of this method is limited to ± 1-2%, the error involved in the Kjeldahl procedure for measuring nitrogen. Thus, the large amounts of bacterial nitrogen necessary for absorption and the relatively low agglutinin nitrogen content of the antisera indicated that the results of one, or at the most two, absorptions be used to calculate values with some meaning in terms of quantitative analytical chemistry. Analysis of an unknown antiserum can now be accomplished in one or two absorptions if 1.0 ml. volumes of appr...