Masters Theses

Date of Award

8-1983

Degree Type

Thesis

Degree Name

Master of Science

Major

Microbiology

Major Professor

Thomas C. Montie

Committee Members

David A. Bemis, Robert N. Moore

Abstract

Pseudomonas cepacia, a clinically important opportunist, was examined with respect to its flagellin characteristics and its virulence in the burned mouse model. Sodium dodecyl sulfate poly acrylamide gel electrophoresis was used to characterize the flagellins from several clinically important non-aeruginosa pseudomonads. The flagellin molecular weights were found to vary between species: P. maltophilia B69 Fla—33,000; P. stutzeri HEW—55,000; P. aeruqinosa M-2—53,000. Upon examination of ten clinical strains, the flagellins of P. cepacia were divided into two groups based on flagellin molecular weights and serological relationships, Type I is a homologous group with a molecular weight of 31,000, whereas Type II is a heterologous group with flagellin molecular weights from 44,000 to 46,000. The characteristics of the two groups are further reflected in their serological relationships. Hyperimmune antisera prepared against Type I FAg agglutinated only Type I strains. Based upon slide agglutination assays, subgroups were detected within Type II. The two flagellin types appear to be analogous to the two major flagellin groups of P. aeruginosa.

The virulence of Pseudomonas aeruginosa and non-aeruginosa pseudomonads was examined in a burned mouse model. Pseudomonas aeruginosa strain M-2 was highly virulent causing 100% mortality by 38 hours with injection of 10 CFU by either a subcutaneous or intra2 peritoneal route. Subcutaneous injection of 102 CFU resulted in rapid multiplication of the bacteria at the burn wound with 108 CFU/g detectable in the burned skin by 28 hours post-injection, 105 CFU/g liver and 103 CFU/ml blood, markedly less virulent; injection of ≥ 107 CFU caused ≤ 60% lethality. Pseudomonas cepacia SMH colonized the burn skin of thermally injured mice, persisting at levels of 107 to 108 CFU/g burned skin after an Pseudomonas cepacia persisted in the burn wound for at least three weeks. No organ invasion was detectable throughout this period. Studies with E. coli and two additional clinical isolates of P. cepacia yielded similar results. Injection of a 102 CFU dose of P. cepacia SMH revealed that the level of persistence is dose dependent. These results suggest that tenacious persistence of P. cepacia in the burn wound may provide a model for the study of persistent, nuisance infections in a compromised host.

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