Interaction of subminimal inhibitory concentrations of clindamycin and escherichia coli: Effects on adhesion and polymorphonuclear leukocyte function

Subinhibitory concentrations (sub-MICs) of clindamycin interfere with the adhesion of Escherichia coli to buccal epithelial cells and promote phagocytosis and killing of this organism by human polymorphonuclear leukocytes (PMNLs). Adherence of E. coli grown in the presence of clindamycin, at concentrations of 2-32 mg/1, varied from 21.1 ±7.4 to 25.8±7.8 bacteria per epithelial cell (EC) (mean±S.D.) as compared with 58.3 ± 10.3 per EC when the organism was cultured in the absence of the antibiotic (P<0.01). The number of phagocytosed bacteria per 200 PMNLs increased from 166.1 ±36.6 when E. coli was grown in medium 199 containing no antibiotic, to 289.3±56.4 (P<001) when the organism was preincubated with 4 mg/1 of clindamycin. The same concentration of clindamycin also increased the percentage of phagocytosed bacteria killed by the PMNLs from 42.0±9.0% to 63.7±11.2% (P<0.01). The results of this study indicate that sub-MICs of clindamycin enhance host-defence mechanisms against E. coli. © 1984 by The British Society for Antimicrobial Chemotherapy

Interaction of subminimal inhibitory concentrations of clindamycin and gram-negative aerobic organisms: Effects on adhesion and polymorphonuclear leukocyte function

The effect of pre-incubation of Pseudomonas aeruginosa, Klebsiella pneumoniae and Proteus mirabilis with sub-inhibitory concentrations (sub MICs) of clindamycin on the adherence of these organisms was studied. Culturing these organising in the presence of clindamycin (4 mg/1) resulted in significant enhancement of adherence for Ps. aeruginosa and Pr. mirabilis and decreased adherence for K. pneumoniae. Furthermore, the effect of pre-exposure to clindamycin on polymorphonuclear leukocyte (PMNLs) function against these organisms was determined. Filtrates of Pr. mirabilis pre-exposed to clindamycin promoted PMNL chemotaxis No effect on chemotaxis was noted with the filtrates of clindamycin treated Ps. aeruginosa and K. pneumoniae. PMNL phagocytosis for all the organisms was increased after they were pre-exposed to clndamycin. © 1986 by The British Society for Antimicrobial Chemotherapy

Interaction between Clostridium difficile and polymorphonuclear leucocytes from the elderly and post-operative cancer patients: phagocytosis and bactericidal function

The ability of polymorphonuclear leucocytes (PMNs) from elderly healthy subjects and post-operative cancer patients to ingest and kill Clostridium difficile was studied. The percentage of phagocytosis in clinically healthy subjects aged 69-82 years ranged from 20.2±3.2 (mean±SD) to 34.1±4.2, depending on the strain of C. difficile, from 6.7±2.2 to 11.2±2.2 in post-operative cancer patients aged 65-69, and from 68.4±3.1 to 81.1±6.3 in young healthy control subjects. In both study groups, the defect was in part serum-associated. Although the total number of bacteria killed by the PMNs was reduced in the two study groups, the percentage of ingested bacteria killed by the PMNs was similar to that in the young healthy subjects. These differences were not noted when Escherichia coli and Staphylococcus aureus were used as the test organisms. The defective PMN function against C. difficile in the elderly and post-operative cancer patients described in this study may offer an explanation as to why these individuals are at high risk of developing antibiotic-associated colitis. © 1984 Springer-Verlag

Transient improvement of polymorphonuclear leukocyte function by splenectomy in β-thalassemia

Host defense mechanisms in transfusion-dependent non-splenectomized patients with β-thalassemia were studied. Polymorphonuclear leukocytes (PMNLs) of non-splenectomized patients responded poorly to zymosan generated chemotactic factors. Chemotactic indices were 22.1 μm ± 2.8 (mean ± S.D.) using zymosan activated serum (ZAS) as the attractant in comparison to 20.4 μm ± 2.6 when fresh untreated serum was used. In contrast, chemotactic indices of normal PMNLs increased from 21.1 μm to 33.6 μm ± 3.1 in response to ZAS. Normal PMNL responses to a mixture of normal ZAS and thalassemic serum were inhibited; the mean chemotactic index was 18.1 μm ± 5.1 with use of ZAS alone. Splenectomy temporarily reverses these alterations. Adherence to nylon wool of PMNLs suspended in fresh thalassemic serum prior to splenectomy was 3.1% ± 1.1 (mean ± S.D.); 20 days after splenectomy adherence increased to 14.0% ± 2.8 (P = 0.0001) and remained at this level for 90 days. At 120 and 150 days after splenectomy adherence decreased to 1.5% ± 0.8 and 1.0% ± 0.85 respectively. Splenectomy also transiently abrogated the failure of zymosan to generate chemotactic factors in thalassemic serum. © 1987 Springer-Verlag