Evaluation of Bactericidal Action of Serum Collected from Paratyphoid Patients and Normal Human against Salmonella Paratyphi

A comparative study of susceptibility of clinical isolates of Salmonella Paratyphi to bactericidal action of S. Paratyphi infected human serum and uninfected human serum was investigated. Bactericidal action of S. Paratyphi infected human serum and uninfected human serum was assessed after incubating the bacterial suspension of S. Paratyphi with 40% of both infected and unifected human serum at various incubation times. Eight samples of S. Paratyphi infected serum from the patients diagnosed with paratyphoid fever were used. The investigation found that the serum killed S. Paratyphi both by classical and alternative pathways. Anti- S. Paratyphi antibodies for the bactericidal action of serum were examined by the assessment of bactericidal activity of non-immune normal human serum. Significant killing of S. Paratyphi by S. Paratyphi infected serum was investigated and the serum mediated killing was increased by increasing the incubation time. The mean growth declines gradually as the incubation time was increased. No noteworthy serum mediated killing was observed for normal human serum and inactivated (heat induced) S. Paratyphi infected serum. Dhaka Univ. J. Pharm. Sci. 12(1): 71-75, 2013 (June) DOI: http://dx.doi.org/10.3329/dujps.v12i1.16303

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THE PROPERDIN SYSTEM AND IMMUNITY

Journal of Experimental Medicine ◽

10.1084/jem.103.5.553 ◽

1956 ◽

Vol 103 (5) ◽

pp. 553-575 ◽

Cited By ~ 97

Author(s):

Alastair C. Wardlaw ◽

Louis Pillemer

Keyword(s):

Human Serum ◽

Bactericidal Activity ◽

Quantitative Relationship ◽

Normal Human Serum ◽

Natural Resistance ◽

Bactericidal Action ◽

Individual Strain ◽

Normal Human ◽

Resistant Strains ◽

The Individual

Methods for the preparation and standardization of reagents suitable for studies on the bactericidal action of the properdin system are described. The preparation and properties of serum free of properdin (RPb) are presented in detail because of the necessity for a suitable RPb in these studies. The properdin system is responsible for the bactericidal action of normal human serum against a variety of microorganisms. The present work shows that the removal of properdin from serum also removes bactericidal activity. Addition of properdin to properdin-deficient serum restores bactericidal activity. A quantitative relationship exists between the final properdin concentration and bactericidal activity against sensitive organisms. The possibilities of a bactericidal assay for properdin are discussed. It is demonstrated that, in addition to properdin, the four components of complement (present in RPb) are necessary for the destruction of properdinsensitive bacteria. If any component is missing, bactericidal activity is lost; when the component is replaced, bactericidal activity is restored. Magnesium is also necessary for the bactericidal activity of the properdin system. Maximal bactericidal activity is obtained with magnesium concentrations similar to that of normal human serum (10–3 to 10–4 M). The bactericidal activity of the properdin system occurs only at temperatures above 15°. Resistant strains have been encountered in species of bacteria sensitive to the properdin system. Resistance or sensitivity is a characteristic of the individual strain and not of the species. The widespread occurrence of the properdin system in normal mammalian serum and the variety of bacteria destroyed by it suggest that the properdin system is a factor in natural resistance.

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