Bacteriostatic Activity of Serum Against Staphylococci

Abstract

Antistaphylococcal activity of normal serum against strains exhibiting various patterns of coagulase, clumping-factor, and staphylokinase production is not connected with the presence of these factors. Purified coagulase does not influence this property of serum. Coagulase-negative strains with clumpingfactor activity grow in normal serum as typical pathogenic staphylococci. Serum bacteriostatic activity against staphylococci may be reversed by several nonspecific factors, such as sterile broth, supernatant fluids of coagulase-negative strains, and ammonium sulfate precipitates of culture supernatant fluids of various staphylococci. Immune sera with a high agglutinating titer for staphylococcal cells do not prevent growth of serum-resistant strains; serum-susceptible strains are inhibited as in normal serum control. Activation or blocking of the serum fibrinolytic system does not influence serum bacteriostatic activity. The growth rate of serum-resistant strains is identical in serum and in Todd-Hewitt broth; serum-susceptible strains are inhibited to the inoculum level, but decreases and increases in viable count are noted during a 24-hr observation period. Observations made with sera of 10 animal species clearly demonstrated differences in serum bacteriostatic activity, mouse serum being completely noninhibitory and cat serum only weakly inhibitory. The technique of quantitative determination of serum susceptibility of staphylococci is described, and the importance of serum antistaphylococcal activity in vitro is discussed. Experimental staphylococcal infection produced in rabbits by intravenous injection of different Staphylococcus aureus strains did not result in significant changes in serum antistaphylococcal activity. The technique of experimental infection used caused chronic infection, with a peak on the 14th day; this was proved by means of a newly developed 5'-nucleotidase test. At the same time, sera of infected animals exhibited slight inhibitory properties, which returned to initial values 1 week later. Infection was produced by strains recognized as nonpathogenic and was inhibited in vitro by sera from both normal and infected rabbits. It is concluded that antistaphylococcal activity of serum should be considered as an "in vitro" phenomenon, which seems to have no importance in defense mechanisms of rabbits infected intravenously with staphylococci. Coagulase-positive strains of Staphylococcus aureus isolated from pathological material multiply readily in normal human serum, whereas nonpathogenic strains are inhibited (19, 20, 21). This phenomenon was found to be independent of complement and lysozyme and to be produced by a thermostable factor present in fresh serum (8, 18). Resistance of pathogenic staphylococci to the action of normal sera has aroused interest in the mechanism of nonspecific resistance to infection by these strains, especially after presentation 953 of a hypothesis on reversing of serum antistaphylococcal activity by coagulase (5). According to Ekstedt (3, 4), this activity depen...

Serum Bacteriostasis of Staphylococcus aureus

“…There are a number of studies demonstrating serum bacteriostasis of S. aureus (5,9,16), and methods of different investigators vary considerably. The system described by Cybulska and Jeljaszewicz (5) was inhibited by broth and saline and was clearly different from that employed here, in which both broth and saline were utilized.…”

“…The biological significance of serum bacteriostasis is obscure. Protection against S. aureus infection in experimental animals has been related to serum bacteriostasis by some but not all investigators (5,20,31).…”

Non‐specific Antimicrobial Defences of the Avian Egg, Embryo and Neonate

“…Non-antibody bactericidins for Staph. aureus (Cybulska & Jeljaszewicz, 1966) and Sat. galtinaru~ (Solomon, 1968b) can also be demonstrated in chicken serum but they do not appear to be involved in resistance to infection with these two organisms.…”

Further Studies on a Serum Nonantibody α Globulin with Antistaphylococcal Activity

“…Several investigations reported in recent years were concerned with the antibacterial activity of serum (Skarnes & Watson, 1957;Cybulska & Jeljaszewicz, 1966; Ehrenh a m , Elliot & Zarco, 1971). Various antibacterial serum fractions such as plakin (Hirsch, 1960), leukin (Skarnes & Watson, 1956), and fl lysin (Johnson & Donaldson, 1968) have also been described and an ABA has been described by Yotis (1962).…”