Effect of Dihydrostreptomycin on Phagocytosis of Mouse-Peritoneal Macrophages In Vitro

Self Cite

An in vitro system was developed to test the phagocytic activity of human macrophages grown from blood monocytes in the presence of the antibiotics ampicillin, tetracycline, and chloramphenicol. 'H-labeled Listeria monocytogenes served as test organism. Subinhibitory amounts of the antibiotics enhanced the phagocytic activity significantly (P < 0.025). Macrophages pretreated with the drugs in identical concentrations showed the same phagocytic activity as control cells in the absence of the drugs. Because the drug concentrations used were similar to those that may be attained in man at certain places of inflammation, enhanced phagocytosis in the presence of antibiotics may have clinical significance.

Section: Resultssupporting

confidence: 88%

Enhanced In Vitro Phagocytosis of Listeria monocytogenes by Human Monocytes in the Presence of Ampicillin, Tetracycline, and Chloramphenicol

Adam¹,

Schaffert²,

Marget³

1974

Self Cite

“…This is in keeping with the report of Bonventre and Imhoff (3) that streptomycin is steadily concentrated in macrophages over a period of 6 days. Recently, Adam et al (1) reported a rapid enhancement in the destruction of bacteria by macrophages when phagocytosis is allowed to proceed in the presence of subliminal amounts of streptomycin. In the present exl)eriments, the penetration of small amounts of antibiotics into the macrophages may have beeil sufficient to l)revent bacterial division.…”

Section: Resultsmentioning

confidence: 99%

Interaction of Virulent and Avirulent Listeria monocytogenes with Cultured Mouse Peritoneal Macrophages

Wilder

Edberg

1973

The interaction between smooth and rough Listeria monocytogenes and mouse peritoneal macrophages in culture was investigated. Initially, antibiotics were deleted from the culture medium, and no attempt other than the removal of unphagocytized bacteria by extensive washings was made to control extracellular growth. Under these conditions the monolayers were rapidly destroyed within an 8-h period, and this was associated with increases in the intracellular population of both strains. Extracellular viability counts revealed that washings failed to reduce the bacteria in the medium to less than 10 % of the original inoculum. Continuous phagocytosis of Li8teria which grew logarithmically in the maintenance media appears to account for the observed changes in the number of intracellular bacteria. The data also indicate that it is primarily the free bacteria in the culture medium which are responsible for the cytotoxic effects. In other experiments streptomycin-penicillin solutions were added to the maintenance media after an initial period of phagocytosis. In the presence of antibiotics, the total number of macrophages per field remained relatively constant, and no morphological alterations in the leukocyte cultures were observable. Extensive intracellular multiplication of either strain was not evident in fixed and stained cover slips. Viable intracellular counts reveal that after 24 h there is almost total killing of the rough variant, whereas the smooth strain tended towards complete survival.on August 8, 2020 by guest http://iai.asm.org/ Downloaded from

“…An antibiotic mixture utilized to eliminate adherent or extracellular bacteria is not internalized, nor is it present throughout the postengulfment period when resident or exocytosed organisms are removed by periodic washing of the culture. By effectively controlling unphago- Resident 1 (1) 1 (1) 1 (1) Thioglycolate 16 (2) NDC ND Fetal calf serum 11 (2) ND ND Listeria antigen 12 (1) 1 (1) 1 (1) Listeria immune 1 (1) 1 (1) 1 (1) Immune Listeria antigen 5 (1) 6 (1) 5 (1) elicited Immune thioglycolate elicited 12 (2) 5 (1) 2 (1) Immune fetal calf serum 1 (1) 1 (1) 1 (1) elicited a Peritoneal cells were collected from mice treated intraperitoneally 1 day previously with 1 ml of fetal calf serum or 5 days previously with either 1 ml of 3% fluid thioglycolate or 106 heat-killed Listeria (antigen) and from 7-day Listeria-immune animals elicited with either antigen, thioglycolate, or fetal calf serum 18 h before assay.…”

Section: Discussionmentioning

confidence: 99%

“…In many instances, it is not clear whether immune macrophages in culture are bactericidal, bacteriostatic, or merely capable of inhibiting the rate ofintracellular bacterial growth. Several studies indicate that macrophage antibacterial activity may be an artifact of the internalization of drugs utilized to restrict the growth of adherent or unphagocytized bacteria in the cultivation medium (1,9,21). Determinations of intracellular killing may also be confused with extracellular bacterial sterilization by secretory products of activated macrophages (3,19).…”

mentioning

confidence: 99%

Fate of Listeria monocytogenes in resident and activated macrophages

Harrington-Fowler¹,

Henson²,

Wilder³

1981

A sensitive and highly reproducible assay was utilized to study in vitro interactions of Listeria monocytogenes with resident and activated macrophages. The technique is not compromised by extracellular events and can readily differentiate between the efficiency of ingestion and the postphagocytic fate of bacteria. Heat-labile factors in human or homologous serum markedly enhanced the phagocytosis of Listeria without noticeably affecting the intracellular fate of the microorganisms. The behavior of Listeria within macrophages cultivated from C57BL/6 and BALB/c mouse strains corresponded to previous reports of in vivo growth patterns in inbred mice. Thioglycolate- or caseinate-elicited macrophages, although highly phagocytic, were unable to prevent the proliferation of Listeria. A bactericidal macrophage population was derived from from C57BL/6 mice which had been immunized intraperitoneally with a sublethal dose of L. monocytogenes and subsequently boosted with heat-killed homologous organisms. Elicitation of immune animals produced an increase in the percentage of peroxidase-positive macrophages, but this activity could not be correlated with restriction of intracellular bacterial growth.