Activity Of Fresh Human Serum Research Articles

Characteristics of Pseudomonas aeruginosa strains isolated from urinary tract infections.

Thirty-three uropathogenic strains of Pseudomonas aeruginosa were investigated for hemolytic activity in both bacterial broth culture filtrates and isolate lyzates, resistance to bactericidal activity of fresh human serum, resistance to six antibiotics and plasmid DNA profile. Twenty-four of the 33 (73%) bacterial filtrates showed lysis of rabbit erythrocytes, as did the three after guinea-pig erythrocyte treatment. Twelve of 33 isolate lysates showed in parallel lysis of both types of erythrocytes used. Serum resistance was found in 17 (52%) isolates, intermediate resistance in 15 (45 %) isolates and only one isolate showed serum sensitivity. Resistance to antibiotics was detected as follows (in %): tetracycline 94, kanamycin 79, chloramphenicol 76, septrin 73, ampicillin 64, streptomycin 45, gentamicin 18. None of the isolates investigated showed resistance to colistine. With the exception of one isolate, plasmid DNA was detected in all P. aeruginosa strains.

Sialylation of lipopolysaccharide and loss of absorption of bactericidal antibody during conversion of gonococci to serum resistance by cytidine 5′-monophospho-N-acetyl neuraminic acid

Changes in lipopolysaccharide (LPS) which occur when serum susceptible gonococci are converted to resistance by incubation with cytidine 5′-monophospho-N-acetyl neuraminic acid (CMP-NANA) have been investigated. Transfer of radioactivity to bacterial LPS from CMP-NANA labelled with 14C in the NANA moiety was detected by fluorography following lysis, proteinase K digestion and SDS-PAGE. Incorporation of radioactivity was inhibited by cytidine 5′-monophosphate (CMP). Both the radioactivity of the LPS and the resistance of gonococci to fresh human serum were largely lost after incubation with neuraminidase. No evidence was obtained to suggest that CMP-NANA is an inducer of new protein synthesis as well as a substrate for the sialylation of LPS. Little radioactivity was incorporated into components other than LPS. Sialylated, serum resistant gonococci were less able than serum susceptible gonococci to absorb the bactericidal activity of fresh human serum. Hence, we conclude that serum resistance conferred on gonococci by CMP-NANA is due to transfer of sialyl groups to surface LPS sites and this inhibits their reaction with bactericidal antibody in human serum.

Examination of the bactericidal and opsonic activity of normal human serum for a mucoid and nonmucoid strain ofPseudomonas aeruginosa

The bactericidal and opsonic activity of fresh human serum (FHS) for a mucoid strain ofPseudomonas aeruginosa, 144M, and its spontaneous nonmucoid revertant, 144NM, was examined. Strain 144M was sensitive to the bactericidal activity of FHS, but strain 144NM was not. This bactericidal activity was due to the combined interaction of IgG and IgM with complement, activated through both pathways. Neither 144M nor 144NM was ingested by human polymorphonuclear leukocytes (PMNL) without FHS. Whereas maximal phagocytosis of 144M required only 5% FHS, comparable ingestion of 144NM required 25% FHS. Maximal phagocytosis of either 144M or 144NM required IgG, IgM, and complement. However, 144M required a heat-sensitive opsonic IgG, whereas 144NM required a heat-resistant IgG. Using selective absorption techniques, the targets for bactericidal and opsonic immunoglobulins on 144M and 144NM appeared to be different, suggesting that the variant 144NM had one or more altered, absent, or inaccessible cell surface components that account for differences in response to FHS and PMNL.

Enhancement of Human Serum Bactericidal Activity by Specific IgM Antibodies of Normal and Anti-O Immune Rabbit Sera Against Pseudo-Serum-Resistant Strains of Serratia marcescens

Abstract Fresh and heat-inactivated (56 °C, 30 min) normal (control) rabbit sera (at 40 vol%) were found to “enhance” the bactericidal activity of fresh human serum (50 vol%) against two „non-serum-sensitive“ (NSS) assay strains of Serratia marcescens (strains CDC O6:H3 and CDC O10:H8). Cells of these two strains were killed in a delayed fashion following addition of normal rabbit serum to human serum. However, strain PO16:H-proved as resistant as before. The crude gamma globulin fractions (at 10 vol%) derived from control rabbit sera “enhanced” human serum bactericidal activity against strains CDC O6:H3 and CDC O10: H8. Homologous anti-O rabbit immune serum, when added at 40 vol % to 50 vol% of fresh human serum, augmented the latter serum's bactericidal activity against S. marcescens strain CDC O6:H3, but not against the other two NSS assay strains. Dual absorptions of heat-inactivated normal rabbit serum with homologous O-cells of S. marcescens abolished the “enhancing” effect. In contrast, dual absorpitons of rabbit control sera with gently killed, protein A-carrying cells of Staphylococcus aureus strain Cowan I, a treatment known to selectively remove rabbit IgG but not IgM immunoglobulins, did not remove the “enhancing” effect against strains CDC O6:H3 and CDC O10:H8. Also, dual absorptions of homologous rabbit anti-O immune sera with protein A resulted in “enhancement” of human serum bactericidal activity against strains CDC O6:H3 and CDC O10:H8, a finding explicable by selective removal of competing (“blocking”) immune IgG antibodies by this treatment. It was concluded that O-antigen-specific, natural and immune antibodies from normal (control) and anti-O immune rabbit sera, respectively, of the IgM immunoglobulin class accounted for the observed “enhancement” of the bactericidal activity of fresh human serum against two of the three assay strains of S. marcescens. Since these two strains were merely apparently serum-resistant, in that their serum-resistance was overcome by the presence of adequate amounts of natural or immune specific IgM antibodies in this in vitro system, or by removal of competing (“blocking”) IgG immune antibodies from anti-O immune sera, it is proposed that these 2 strains be designated as “pseudo-serum-resistant” (PSR), in order to differentiate these from genuinely NSS strains of S. marcescens, such as strain PO16:H-.

Susceptibility of Serratia marcescens to Human Serum: Antagonism of Serum Bactericidal Activity by IgG Immunoglobulins of Homologous Rabbit Anti-O Sera

Absorption of fresh human serum with boiled or live homologous O-cells of Serratia marcescens in the cold (4 degrees C, 1 hour) completely abrogated killing activity against "delayed serum-sensitive" (DSS) strains of S. marcescens. In contrast, previously "promptly serum-sensitive" (PSS) strains of S. marcescens and the PSS control strain Escherichia coli C were killed kinetically in a slightly "delayed" fashion by antibody-depleted fresh human serum. Addition of 40 vol% of heat-inactivated homologous rabbit anti-O immune sera to 50 vol% of fresh human serum "blocked" bactericidal activity against DDS and PSS assay strains of S. marcescens. The "blocking" activity of rabbit anti-O immune sera was shown to reside in the crude gamma globulin fractions derived therefrom through precipitation with ammonium sulfate. Absorption of rabbit anti-O immune sera with boiled homologous O-cells failed to remove the "blocking" activity; the O-agglutination titers were reduced to nondetectable levels. However, dual absorptions of rabbit anti-O immune sera with killed cells of Staphylococcus aureus Cowan I (protein A) almost completely abolished "blocking" activity; the O-agglutinin titers of these immune sera were not reduced more than 4-fold. Immunoelectrophoresis and rocket electroimmuno assays. employing heavy chain-specific goat anti-rabbit IgG and IgM sera, respectively, established that dual protein A-absorption selectively removed rabbit IgG, but not rabbit IgM, immunoglobulins. It was concluded that rabbit immunoglobulins of the IgG class accounted for the observed in vitro antagonism of the bactericidal activity of fresh human serum against DSS and PSS strains of S. marcescens.

Nonspecific Aminoglycoside Cross-Resistance of <i>Serratia marcescens</i>

10 of 11 clinical isolates of Serratia marcescens yielded small numbers (10(-7) to 10(-8)) of 'gray' colony-type variants after selection with either amikacin, gentamicin or kanamycin, of which most proved resistant against all of the following aminoglycoside antibiotics: amikacin, gentamicin, kanamycin, neomycin, netilmicin, sisomicin and streptomycin. The level of resistance was not absolute, but rather low-level to intermediate. All except two of these 'gray', resistant phenotypic variants yielded 'opaque' revertants which were essentially indistinguishable from the parent (wild type) strains in terms of colonial morphology and antibiotic susceptibility. The 'gray' variants kinetically were more susceptible to the bactericidal activity of fresh human serum than the 'opaque' variants. Preliminary evidence afforded the tentative conclusion that this nonspecific aminoglycoside-resistance mechanism was not plasmid-mediated.

The Filtrability of the Components of Alexin

Muir and Browning (1909) were the first to show that alexin is retained by the filter when fresh serum is passed through a Berkefeld candle. Several filtrations are generally required to remove all traces of the alexic activity, although when a fresh candle is employed for each filtration, the third or fourth filtrate is usually devoid of alexic power (Schmidt, 1914). It is not established whether or not the failure of later filtrates to haemolyse sensitised erythrocytes results from the removal by the filter of some one or of all of the known components of alexin from the serum. We have, therefore, studied the effect of Berkefeld filtration upon the alexic activity of fresh human serum with respect to the thermolabile elements, and the thermostable third and fourth components (Whitehead, Gordon and Wormall, 1925; Gordon, Whitehead and Wormall, 1926).