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Biomedical subjects

G Leidy

Publications and source records attributed to G Leidy.

14 recordsLinked to original sources
PubMed1988

The use of bacterial interference to prevent infection.

For decades, bacterial strains of low virulence were occasionally used in man to replace or to block colonization by the more virulent organisms and thereby prevent bacterial infection. This paper reviews the topic and presents recent information on the implantation of strain 215 alpha-hemolytic streptococcus (alpha-strep) in the nasopharynx of neonates in the intensive care unit. A single inoculation of strain 215 can change abnormal colonization of the pharynx to "normal" (alpha-strep predominant) in 48-72 h in most neonates. Following implantation, alpha-strep with strain 215 like characteristics fluctuate among naturally occurring strains of alpha-strep, sometimes persisting in dominance and sometimes decreasing rapidly as new strains appear. Strain 215 can survive in the pharynx during subsequent antibiotic therapy and can be recalled to dominance by such therapy. It seems remarkably stable in vivo. There is no evidence of its nosocomial spread in the nursery. Streptococcus with strain 215 like characteristics occurred naturally in 1-6% of neonates in our intensive care unit. No infection (disease) attributable to strain 215 occurred in implanted infants.

Antibiosis↗
PubMed1980

Abnormal colonization of neonates in an ICU: conversion to normal colonization by pharyngeal implantation of alpha hemolytic streptococcus strain 215.

Normal bacterial flora provide a natural defense mechanism against infection. Our experience indicates that "normal" flora for the ICU neonate contains alpha hemolytic (alpha-) streptococci as the predominant organism. The purpose of the current investigation is to study the feasibility of implanting a carefully selected, naturally occurring strain of alpha-streptococcus in the nasopharynx of neonates considered to be at high risk of infection because of the abnormal colonization of their pharynx with potential pathogens. Twenty-two infants in the neonatal intensive care unit have received nasopharyngeal implantation with strain 215 alpha-streptococcus. In 16 infants, alpha-streptococci, including the implant strain in pure or mixed alpha-streptococcal populations, constituted the predominant pharyngeal flora within 48 to 72 hr of implantation. The implant strain was not recovered from the remaining six infants. The procedure was apparently innocuous in this small number of patients. We conclude that implantation of a streptococcus can be established in the pharynx of infants abnormally colonized with pathogenic organisms in high titer and that successful implantation of strain 215 can result in prompt development of normal pharyngeal flora, with alpha-streptococci predominant, within 48 hr. There has been no evidence of infection or other adverse reaction caused by the implant strain.

Bacterial Infections↗
PubMed1978

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

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 (alpha-streptococci predominating) or cultures showing low titers (less than 10(4) 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.

Anti-Bacterial Agents↗
PubMed1966

Genetic modifiers of the phenotypic level of deoxyribonucleic acid-conferred novobiocin resistance in Haemophilus.

Leidy, Grace (Columbia University, New York, N.Y.), Iris Jaffee, and Hattie E. Alexander. Genetic modifiers of the phenotypic level of deoxyribonucleic acid-conferred novobiocin resistance in Haemophilus. J. Bacteriol. 92:1464-1468. 1966.-An apparent increase in novobiocin resistance in Haemophilus aegyptius after a second exposure to a particular H. influenzae transforming deoxyribonucleic acid was shown to be the result not of multi-step transformation but of the action of a gene functioning as an enhancement modifier. The modifier is very closely linked to a streptomycin resistance gene (which is linked to a novobiocin resistance marker); it affects the natural degree of resistance to both novobiocin and kanamycin to a measurable degree. Evidence of a repressor of the enhancement modifier is reported.

DNA, Bacterial↗