Bactericidal, Bacteriolytic and Opsonic Activity of Human Serum Against Escherichia Coli

Rozenberg-Arska, M.; Porsius, J. C.; Jaarsma, Emmy Y.; Verhoef, J.

doi:10.1099/00222615-22-2-143

Cited by 11 publications

(6 citation statements)

References 12 publications

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“…The results of our study confirm those reported previously that unencapsulated strains incubated in low concentrations of serum are easily ingested by granulocytes (8,19,21), whereas encapsulated strains are not effectively opsonized in serum. Extracellular polysaccharide may play an important role in the protection of bacteria against serum opsonic activity (1,3,16,20).…”

Section: Discussionsupporting

confidence: 82%

Enhanced phagocytosis of encapsulated Escherichia coli strains after exposure to sub-MICs of antibiotics is correlated to changes of the bacterial cell surface

Raponi¹,

Keller²,

Overbeek³

et al. 1990

Antimicrob Agents Chemother

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The influence of five antibiotics (netilmicin, ceftriaxone, cefepime, fleroxacin, and ciprofloxacin) on capsular polysaccharide distribution and on opsonophagocytosis by human polymorphonuclear leukocytes of unencapsulated and encapsulated Escherichia coli strains was studied. Unencapsulated E. coli strains were readily opsonized in serum and easily ingested by polymorphonuclear leukocytes, and antibiotics did not further enhance the phagocytosis rates. In contrast, encapsulated bacteria were poorly opsonized in human serum, and phagocytosis was enhanced after overnight exposure to O.5x the MICs of the antibiotics, with the exception of cefepime. Incubation of unencapsulated as well as encapsulated bacteria in complement-inactivated serum markedly reduced the bacterial uptake by polymorphonuclear leukocytes regardless of the presence of antibiotics. Slide agglutination assays, performed either with a monoclonal antibody for capsular polysaccharide or with an antiserum raised against the stable unencapsulated mutant E. coli 07:K-, showed reduction but not lack of the capsular polysaccharide of encapsulated E. coli 07:K1, and better exposure of subcapsular epitopes, after incubation with 0.5 x the MICs of antibiotics. Flow cytometric analysis of encapsulated E. coli exposed to netilmicin, ciprofloxacin, and fleroxacin revealed that the reduction in capsular material was homogeneous among the bacterial population. Treatment with cefepime and ceftriaxone induced two populations of bacteria that differed in the amount of K antigen present. These results indicate that sub-MICs of netilmicin, ceftriaxone, fleroxacin, and ciprofloxacin influenced complement-mediated opsonization, probably due to changes in the capsular polysaccharide structure.The outer structures of bacteria play an important role in the interaction between bacteria and host defenses during infections. Encapsulated strains of Escherichia coli have been shown to be resistant to the lytic and opsonic activities of serum (6, 7) and to phagocytosis by human polymorphonuclear leukocytes (PMN) (8). The invasive capacity of these bacteria is correlated to their ability to resist killing by normal human serum (9,14). Especially Kl capsule appears to be responsible for serum resistance of strains that are otherwise exquisitely sensitive to the action of serum (2) and that are easily ingested and degraded by PMN (21). However, during infection bacteria are exposed not only to the defense mechanisms of the host but also to the action of antimicrobial agents. It is well known that antibiotics exert part of their action in the body fluids, at concentrations below the MICs. Sub-MICs of certain antibiotics have been shown to modify the morphological and ultrastructural characteristics of bacteria, influencing the interactions with host defense mechanisms, i.e., opsonophagocytosis (5, 15). In previous studies we reported that preexposure of encapsulated E. coli strains to sub-MICs of an aminoglycoside (netilmicin) and of a cephalosporin (ceftriaxone) enhanced the phag...

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Section: Discussionsupporting

confidence: 82%

Enhanced phagocytosis of encapsulated Escherichia coli strains after exposure to sub-MICs of antibiotics is correlated to changes of the bacterial cell surface

Raponi¹,

Keller²,

Overbeek³

et al. 1990

Antimicrob Agents Chemother

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“…Bacteriolytic effect of the antimicrobial agent is detectable only by assessing the decrease in the OD signal [31–33]. The OD detection limit of the used plate reader, for the bacterial suspension, was approximately 1 × 10 6 cells/well corresponding to 0.030 OD in 200 μ L, and therefore 10-fold higher bacterial cell number (3 × 10 6 cells/well) had to be used in killing experiments.…”

Section: Resultsmentioning

confidence: 99%

The Real-Time-Based Assessment of the Microbial Killing by the Antimicrobial Compounds of Neutrophils

Atosuo

Lilius

2011

The Scientific World JOURNAL

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A recombinant Escherichia coli K-12 strain, transformed with a modified bacterial luciferase gene (luxABCDE) from Photorhabdus luminescens, was constructed in order to monitor the activity of various antimicrobial agents on a real-time basis. This E. coli-lux emitted, without any addition of substrate, constitutive bioluminescence (BL), which correlated to the number of viable bacterial cells. The decrease in BL signal correlated to the number of killed bacterial cells. Antimicrobial activity of hydrogen peroxide (H2O2) and myeloperoxidase (MPO) was assessed. In high concentrations, H2O2 alone had a bacteriocidic function and MPO enhanced this killing by forming hypochlorous acid (HOCl). Taurine, the known HOCl scavenger, blocked the killing by MPO. When E. coli-lux was incubated with neutrophils, similar killing kinetics was recorded as in H2O2/MPO experiments. The opsonization of bacteria enhanced the killing, and the maximum rate of the MPO release from lysosomes coincided with the onset of the killing.

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“…The complement system is an important defence mechanism against various invading pathogens [25]. However, the sensitivity to the bactericidal action of complement varies considerably according to the structural determinants of different bacterial strains [25, 26]. In general, gram‐positive bacteria are relatively resistant to the bacteriolytic activity of complement, probably because their peptidoglycan layer is too thick for the complement‐derived membrane attack complex to penetrate [27, 28].…”

Section: Discussionmentioning

confidence: 99%

Roles of Group IIA Phospholipase A₂ and Complement in Killing of Bacteria by Acute Phase Serum

Grönroos¹,

Salonen²,

Viander³

et al. 2005

Scand J Immunol

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The complement system is regarded as an important component of the innate defence system against invading bacteria. However, synergistic actions between the complement and the other components of innate immunity are incompletely known. Human group IIA phospholipase A 2 (hGIIA PLA 2 ) is an effective antibacterial enzyme in serum of patients with severe bacterial infections. Our aim was to investigate the significance of complement and hGIIA PLA 2 in acute phase serum. Serum samples were collected from patients with acute bacterial infections and from healthy control subjects. We prepared hGIIA PLA 2 -depleted serum by immunoadsorption and inhibited the activity of complement by a specific inhibitor, compstatin. The bactericidal effects of treated and untreated serum were compared by incubating Staphylococcus aureus and Listeria monocytogenes in the presence of serum. Acute phase serum effectively killed S. aureus and L. monocytogenes, and depletion of hGIIA PLA 2 significantly reduced the antibacterial effect. Complement had a weak bactericidal effect against L. monocytogenes. We conclude that hGIIA PLA 2 is the major antibacterial factor in human acute phase serum against the gram-positive bacteria S. aureus and L. monocytogenes, exceeding complement in efficiency.

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Bactericidal, Bacteriolytic and Opsonic Activity of Human Serum Against Escherichia Coli

Cited by 11 publications

References 12 publications

Enhanced phagocytosis of encapsulated Escherichia coli strains after exposure to sub-MICs of antibiotics is correlated to changes of the bacterial cell surface

Enhanced phagocytosis of encapsulated Escherichia coli strains after exposure to sub-MICs of antibiotics is correlated to changes of the bacterial cell surface

The Real-Time-Based Assessment of the Microbial Killing by the Antimicrobial Compounds of Neutrophils

Roles of Group IIA Phospholipase A₂ and Complement in Killing of Bacteria by Acute Phase Serum

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Bactericidal, Bacteriolytic and Opsonic Activity of Human Serum Against Escherichia Coli

Cited by 11 publications

References 12 publications

Enhanced phagocytosis of encapsulated Escherichia coli strains after exposure to sub-MICs of antibiotics is correlated to changes of the bacterial cell surface

Enhanced phagocytosis of encapsulated Escherichia coli strains after exposure to sub-MICs of antibiotics is correlated to changes of the bacterial cell surface

The Real-Time-Based Assessment of the Microbial Killing by the Antimicrobial Compounds of Neutrophils

Roles of Group IIA Phospholipase A2 and Complement in Killing of Bacteria by Acute Phase Serum

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Roles of Group IIA Phospholipase A₂ and Complement in Killing of Bacteria by Acute Phase Serum