[Aminoglycosides once daily: potent but short].
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Aminoglycosides↗
Biomedical subjects
H A Verbrugh
Publications and source records attributed to H A Verbrugh.
Prophylactic ciprofloxacin for catheter-associated urinary-tract infection.
Patients receiving antibiotics during bladder drainage have a lower incidence of urinary-tract infections compared with similar patients not on antibiotics. However, antibiotic prophylaxis in patients with a urinary catheter is opposed because of the fear of inducing resistant bacterial strains. We have done a double-blind, placebo-controlled trial of prophylactic ciprofloxacin in selected groups of surgical patients who had postoperative bladder drainage scheduled to last for 3 to 14 days. Patients were randomly assigned to receive placebo (n = 61), 250 mg ciprofloxacin per day (n = 59), or 500 mg ciprofloxacin twice daily (n = 64) from postoperative day 2 until catheter removal. 75% of placebo patients were bacteriuric at catheter removal compared with 16% of ciprofloxacin-treated patients (relative risk [RR] [95% CI] 4.7 [3.0-7.4]). The prevalence of pyuria among placebo patients increased from 11% to 42% while the catheter was in place; by contrast, the rate of pyuria was 11% or less in patients receiving ciprofloxacin (RR 4.0 [2.1-7.3]). 20% of placebo patients had symptomatic urinary-tract infections, including 3 with septicaemia, compared with 5% of the ciprofloxacin groups (RR 4.0 [1.6-10.2]). Bacteria isolated from urines of placebo patients at catheter removal were mostly species of enterobacteriaceae (37%), staphylococci (26%), and Enterococcus faecalis (20%), whereas species isolated from urines of ciprofloxacin patients were virtually all gram-positive. Ciprofloxacin-resistant mutants of normally sensitive gram-negative bacteria were not observed. Ciprofloxacin prophylaxis is effective and safe in the prevention of catheter-associated urinary tract infection and related morbidity in selected groups of patients requiring 3 to 14 days of bladder drainage.
Adult↗
[Antibiotics, developments and orientation].
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4-Quinolones↗
Peritoneal defense in continuous ambulatory versus continuous cyclic peritoneal dialysis.
Several centers have reported a lower rate of peritonitis among adult patients on continuous cyclic peritoneal dialysis (CCPD) as compared to those undergoing continuous ambulatory peritoneal dialysis (CAPD). Preliminary results of our ongoing prospective randomized study comparing CAPD-Y with CCPD also suggest a lower peritonitis incidence among CCPD-treated patients. To investigate whether the two dialysis regimens could result in differences in local host defense, we studied peritoneal macrophage (PMO) function and effluent opsonic activity in eight patients established on CAPD-Y matched with eight chronic CCPD patients. Since short and long dwell times are inherent to both dialysis modalities, and we previously found that dwell time has an impact on PMO function and effluent opsonic activity, patients were studied after both a short (4 hr) and a long (15 hr) dwell time. In both groups PMO phagocytic capacity increased significantly with dwell time (39 +/- 3.3% at 4 hr vs. 58 +/- 4.2% at 15 hr in CAPD patients, and 40 +/- 3.9 vs. 72 +/- 3.3% in CCPD patients; P less than 0.01), as did PMO peak chemiluminescence response (31 +/- 4.9 vs. 77 +/- 7.2 counts.min-1/10(4) cells in CAPD, and 22 +/- 3.9 vs. 109 +/- 21.2 counts.min-1/10(4) cells in CCPD; P less than 0.01) and effluent opsonic activity (41 +/- 7.6 vs. 73 +/- 5.8% in CAPD and 39 +/- 6.2 vs. 70 +/- 5.9% in CCPD; P less than 0.01). However, no significant difference was found in either variable between CAPD and CCPD patients when dwell times were equal.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Age-related interference with Chlamydia pneumoniae microimmunofluorescence serology due to circulating rheumatoid factor.
Microimmunofluorescence (MIF) serology is commonly used in the diagnosis of chlamydial infections. In the MIF assay, Chlamydia pneumoniae elementary bodies were used to detect C. pneumoniae immunoglobulin G (IgG) and IgM antibodies in paired serum samples from 286 patients with respiratory illnesses. In 69 patients, MIF serology was compared with C. pneumoniae cultures. All C. pneumoniae cultures remained negative. However, 205 (71%) of 286 patients were C. pneumoniae antibody positive and 64 (22%) had MIF test results indicating recent infection; 11 showed a fourfold increase in IgG titer, 18 had IgG titers of greater than or equal to 1:512, and 41 had IgM titers of greater than or equal to 1:16. In 35 (55%) of 64 patients, a recent-infection diagnosis was based on C. pneumoniae IgM antibodies only. However, 78% of C. pneumoniae IgM-positive patients had circulating rheumatoid factor (RF) by rheumatoid arthritis latex assay. RF positivity increased with age. After absorption with anti-human IgG, all C. pneumoniae IgM-positive sera became C. pneumoniae IgM negative in the MIF assay. Twenty-five patients with active rheumatoid arthritis but without respiratory illness were also tested; 14 were C. pneumoniae IgG positive and C. pneumoniae IgM positive as well. Absorption of IgG from these RF-containing sera invariably resulted in disappearance of reactivity in the MIF IgM assay. We conclude that with age the serologic diagnosis of recent C. pneumoniae infection becomes increasingly prone to false-positive results unless sera are routinely absorbed prior to MIF IgM testing.
Adult↗
Thrombogenicity and procoagulant activity of human mesothelial cells.
Cell seeding may decrease the thrombogenicity of implanted vascular grafts, but its application is hampered by the limited availability of autologous endothelial cells. We studied the interaction of alternate cells, human peritoneal mesothelial cells, with whole blood in a flow chamber. When citrated blood was perfused over mesothelial cells, platelet adhesion was seen on the intercellular matrix but not on the cells themselves. Perfusions with blood anticoagulated with low-molecular-weight heparin resulted in fibrin formation at the surface of mesothelial cells but not at the surface of human umbilical venous endothelial cells. At shear rates of 200 sec-1 fibrin deposition on the mesothelial cell surface increased during the first 5 minutes to 5.7 +/- 1.06 micrograms fibrin per square centimeter, whereafter these values stabilized. The procoagulant activity of cultured mesothelial cells was higher than that of peritoneal membrane studied ex vivo. However, cultured mesothelial cells incubated with polyclonal antibodies against tissue factor showed a significant decrease in procoagulant activity. We conclude that human peritoneal mesothelial cells may be used for cell seeding procedures, provided that their tissue factor expression can be controlled.
Blood Coagulation Factors↗
Pharmacokinetics of ciprofloxacin after intraperitoneal administration in uninfected patients undergoing CCPD.
Ciprofloxacin is increasingly used to treat peritoneal dialysis related peritonitis. We studied the pharmacokinetics of intraperitoneally administered ciprofloxacin in six uninfected CCPD patients. In a randomized cross-over setting ciprofloxacin was added either to a long dwell exchange (lastbag) or to four short dwell exchanges (dwell time 1.5 h). Addition of ciprofloxacin (25 mg/l) during the four short dwell exchanges resulted in dialysate levels of 21.1-13.3 mg/l during these exchanges. In the subsequent last bag devoid of ciprofloxacin a dialysate Cmax,D of 1.38 mg/l was observed at 30 min. Mean +/- SD serum Cmax,S was 0.59 +/- 0.29 mg/l after 5.4 h. Instillation of 100 mg/l ciprofloxacin in the last-bag yielded Cmax,D of 99.1 mg/l, falling with a t1/2 of 3.3 h towards levels < 2 mg/l at 19.8 h. A mean +/- SD serum Cmax,S of 0.69 +/- 0.19 was reached after 4 h. During four subsequent 1.5h exchanges without ciprofloxacin dialysate levels were < 0.1 mg/l. Instillation of 25 mg/l ciprofloxacin in the last-bag yielded a Cmax,D of 21.7 mg/l, falling towards levels < 2 mg/l at 15 h with a t1/2 of 3.85 h. A mean +/- SD serum Cmax,S of 0.26 +/- 0.03 was reached after 8 h. We conclude that the rapid absorption of ciprofloxacin from the dialysate into the tissues requires ciprofloxacin to be administered to all CCPD bags to ensure bactericidal dialysate levels. When therapeutic serum levels are required higher intraperitoneal doses or an oral or i.v. loading dose is warranted.
Adult↗
Impact of concurrent antimicrobial therapy on catheter-associated urinary tract infection.
Results of a survey in two Dutch district hospitals which investigated the impact of concurrent administration of antibiotics on the incidence of catheter-associated urinary tract infection (UTI), showed that 61% of catheterized patients received antibiotics at some stage during bladder drainage. The use of antibiotics within 48 hours prior to catheter removal reduced the risk of bacteriuria fivefold. Multivariate analysis of patients who were catheterized for 3-14 days indicated that, apart from the duration of catheter employment, the use of antibiotics was the only variable significantly and independently associated with the development of bacteriuria. The power of this association varied inversely with increasing duration of catheterization but remained significant throughout the 3-14-day interval. Patients with bacteriuria at the time of catheter removal were more likely to have a febrile illness compared to those who remained free of catheter-associated UTI.
Adult↗
Role of mesothelial cells in peritoneal antibacterial defence.
Whether phagocytosis of Staphylococcus aureus by polymorphonuclear neutrophils, monocytes, and peritoneal macrophages takes place when the staphylococci are adherent to monolayers of human mesothelial cells in the absence of opsonins was investigated. Adherence of S aureus to mesothelial monolayers increased significantly when the bacteria were opsonised with pooled human serum, but phagocytosis by polymorphonuclear neutrophils and monocytes occurred independently. Phagocytosis by peritoneal macrophages, however, was only marginal. Pretreatment of polymorphonuclear neutrophils with inhibitors of cellular metabolism and motility reduced their phagocytic capacity. These results indicate that the surface of mesothelial cells provides favourable conditions for the elimination of staphylococci in the peritoneal cavity. Phagocytic motility seems to be important in surface phagocytosis. The inability of peritoneal macrophages to phagocytise staphylococci adherent to the mesothelial cells suggests that they contribute little to the antibacterial defence of the peritoneal membrane of patients receiving peritoneal dialysis.
Cells, Cultured↗
Another reason to restrict the use of a hypertonic, glucose-based peritoneal dialysis fluid: its impact on peritoneal macrophage function in vivo.
Previous in vitro studies have revealed that the currently used peritoneal dialysis fluids (PDFs) inhibit several functions of phagocytic cells. Glucose-mediated hypertonicity was demonstrated to be one of the major detrimental factors. To investigate the clinical relevance of these in vitro findings, we compared the in vivo effect of a PDF with 3.86% glucose (D386) and a PDF containing 1.36% of glucose (D136) on peritoneal macrophage (PMO) function in eight CCPD patients. In a randomized cross-over setting, each patient used exclusively D136 or D386 on day one. The next day the patients who used D136 were switched to D386 and vice versa. PMO were isolated from the effluents and studied for their phagocytic capacity and chemiluminescence response. PMOs obtained from D386 effluents were significantly less phagocytic as compared to PMOs obtained after the in vivo use of D136 (38 +/- 7.1 vs 63 +/- 8.3%, p less than 0.02). In addition PMOs exposed to D386 were less able to mount a respiratory burst (peak response 4 +/- 1.0 vs 15 +/- 1.4% of control cells, p less than 0.05). Thus, the in vivo use of D386 was accompanied by significantly decreased PMO functions. These findings further stress the need to search for alternative solutions that do not rely on glucose-mediated hypertonicity for ultrafiltration.
Adult↗
The effect of glycerol-containing peritoneal dialysis fluid on peritoneal macrophage function in vivo.
Though glucose is universally applied as osmotic agent in CAPD, there is great interest in the use of alternative osmotic agents. Glycerol-containing peritoneal dialysis fluids (G-PDF) have been used in an attempt to minimize the metabolic effects of long-term exposure to glucose, especially in patients with diabetes. Since data were lacking, we studied the effect of G-PDF on peritoneal macrophage (PMO) function. In a randomized cross-over setting eight stable diabetic CAPD patients performed the third and fourth exchange of the day with either G-PDF or with glucose-containing PDF (D-PDF) of comparable osmolality. The next day the patients who had used G-PDF were switched to D-PDF and vice versa. PMO were isolated from the effluents and tested for their phagocytic capacity and chemiluminescence response. No differences were encountered in total and differential white cell counts between G-PDF and D-PDF effluents. PMO phagocytic capacity for both S. epidermidis (SE) and E. coli (EC) was significantly depressed after the instillation of G-PDF as compared to D-PDF (SE: 52 +/- 2.7 vs 69 +/- 5.0%, p less than 0.02, and EC: 44 +/- 5.7 vs 63 +/- 6.7%, p less than 0.02). The same held true for peak chemiluminescence response (5.3 +/- 1.36 vs 7.2 +/- 1.43% of control cells, p less than 0.005). Thus, G-PDF may compromise PMO function in vivo more than D-PDF despite its more favourable metabolic profile as compared to D-PDF for diabetic patients.
Adult↗
Host-parasite relationship in staphylococcal infections: the role of the staphylococcal cell wall during the process of phagocytosis.
Evidence is presented that antibodies against staphylococcal peptidoglycan are important opsonins for phagocytosis of staphylococci. Cell wall protein A inhibits opsonization by IgG through its interaction with the Fc fragment of the IgG molecule and preventing therefore the binding between the Fc fragment and the Fc receptor of the cell membrane of the leukocyte. Extracellular protein A interferes with opsonization presumably through depletion of complement.
Antibodies, Bacterial↗
Escherichia coli K antigen in relation to serum-induced lysis and phagocytosis.
The presence of capsular polysaccharides (K antigens) and their relation to phagocytosis and sensitivity to the lytic action of serum of 26 strains of E. coli isolated from stools of healthy volunteers and from blood cultures were studied. Four of 12 strains isolated from stool cultures and 12 (86%) of the 14 strains isolated from blood cultures possessed K antigen. Three of the 12 strains isolated from stool cultures and seven of the 14 isolated from blood cultures were resistant to uptake by polymorphonuclear leucocytes; these resistant strains contained large amounts of K antigen. By contrast 10 strains, three with low amounts of K antigen and seven without detectable amounts of K antigen, were readily phagocytosed. Thus it appears that K antigen renders E. coli resistant to phagocytosis. Only four (15%) of the 26 strains were sensitive to serum lysis and there was no correlation between the presence of K antigen and the resistance to serum lysis.
Antigens, Bacterial↗
Role of Escherichia coli K capsular antigens during complement activation, C3 fixation, and opsonization.
Escherichia coli strains with K capsular polysaccharides are relatively resistant to phagocytosis by polymorphonuclear leukocytes, in contrast to E. coli strains without K antigens. This inhibition of phagocytosis is related to an impaired recognition of the K+ strains by the phagocytes due to ineffective opsonization. All five strains without K antigens were readily phagocytized after opsonization in 5% normal serum, compared with no uptake of the K+ strains. Evidence is presented that the decreased opsonization of the K+ strains in normal serum is caused by a low rate of complement activation of the strains, with subsequent absence of C3b fixation or C3d fixation or both to the cell wall of the bacteria. After removal of the K+ antigens by heating of a K+ E. coli strain, the strain was able to activate complement, to bind C3b or C3d or both, and to become opsonized. Complement was then activated via the classical and alternative pathways, which was comparable to the complement consumption by K- E. coli.
Antigens, Bacterial↗
Quantitation of the third component of human complement attached to the surface of opsonized bacteria: opsonin-deficient sera and phagocytosis-resistant strains.
The role of the third component of human complement (C3) in the opsonization of bacteria in nonimmune human sera was evaluated. The amount of C3 that becomes attached to the surface of bacteria upon incubation in serum was measured in a quantitative fluorescent immunoassay using fluorescein-conjugated monospecific antiserum to human C3. The intensity of the fluorescence from opsonized bacteria was found to be directly proportional to the absolute amount of C3 fixed, and this enabled the detection of as few as 300 molecules of bound C3 per bacterium. In normal serum the rate of C3 fixation was closely correlated with an increase in opsonization of the bacteria for human PMNs. Both C3 fixation and opsonization were maximal after 15 min of incubation. C3 fixation was also observed, albeit at a significantly slower rate, in human serum with a nonfunctional classical pathway but an intact alternative complement pathway and in serum deficient in immunoglobulins. Again, the kinetics of C3 fixation correlated with bacterial opsonization. Using a total of 21 strains of several bacterial species, including Staphylococcus aureus and Escherichia coli, encapsulation of bacteria was found to interfere with the process of C3 fixation in normal human serum, rendering these organisms resistant to subsequent phagocytosis by human polymorphonuclear leukocytes.
Bacteria↗
Staphylococcus aureus opsonization mediated via the classical and alternative complement pathways. A kinetic study using MgEGTA chelated serum and human sera deficient in IgG and complement factors C1s and C2.
Staphylococcus aureus opsonization was studied kinetically by: (1) determination of the uptake of [3H]-thymidine labelled bacteria by human PMN's; (2) fluorescent anti-C3 and anti-IgG staining of opsonized bacteria; and (3) measuring bacterial complement consumption. Maximum opsonization in normal serum occurred within 5 min of incubation. About 80% of staphylococci were then taken up by PMN's, and IgG and C3b could be detected on the bacterial surface. In the absence of a functional classical complement pathway, as in sera deficient in C1s and C2 and in MgEGTA chelated serum, maximal opsonization was only achieved after 30--60 min incubation. Opsonization in IgG deficient serum occurred at a rate similar to that found in C2 deficient or MgEGTA chelated serum. Opsonization was greatly enhanced when sera were reconstituted. It was concluded that in IgG deficient serum Staphylococcus aureus opsonization is mediated via the alternative complement pathway. Dilution of normal serum primarily affected the classical complement pathway, resulting in a decreased rate of opsonization. In normal serum IgG did not appear to be a rate-limiting factor. S. Aureus opsonization was best studied by the phagocytosis assay and the fluorescent-antibody technique. Measuring haemolytic complement consumption was found to be an insensitive indicator of bacterial complement activation and opsonization.
Complement Activation↗
The role of Staphylococcus aureus cell-wall peptidoglycan, teichoic acid and protein A in the processes of complement activation and opsonization.
The role of cell-wall peptidoglycan, teichoic acid and protein A in the processes of Staphylococcus aureus complement activation and opsonization was investigated. CH50 consumption studies reveal that, although all cell-surface fractions were capable of activating the classical C pathway, only peptidoglycan consumed C via the alternative pathway. Using a quantitative immunofluorescence assay, peptidoglycan was shown to bind C3 molecules via the classical as well as via the alternative C pathway and in the absence of IgG and IgA class antibodies. C activation via the classical and the alternative pathway could be distinguished by kinetic analysis. By comparing the rates of staphylococcal C consumption, C3 fixation and opsonization it was found that the CH50 consumption assay is a relatively insensitive method and may yield results that do not necessarily reflect the process of bacterial opsonization.
Complement Activation↗
Phagocytosis and killing of staphylococci by human polymorphonuclear and mononuclear leucocytes.
The phagocytosis and killing of 3H-thymidine-labelled Staphylococcus aureus by polymorphonuclear leucocytes (PMNs) and monocytes (MNs) obtained from 50 health donors were evaluated. In addition, extracellular factors that might influence phagocytosis and killing were studied. The method described gave highly reproducible results. No significant difference was observed in the phagocytic and killing functions of a single donor's PMNs and MNs when studied several times in one day and longitudinally over a period of 1-12 weeks for six donors tested. Likewise, no signigicant difference in uptake and killing was observed when bacteria were opsonised with sera from 11 different normal donors. When Staph. aureus opsonised with normal serum was added to the leucocytes in a ratio of 10 bacteria: 1 leucocyte, the uptake by PMNs and MNs from 50 donors after 20 minutes' incubation was 85% +/- 7 standard deviation (SD) (range 75-98%) and 69% +/- 11 SD (range 54-90%), respectively. The rate of uptake by MNs in the first three minutes of the assay period was only 60% of that by PMNs.
Blood Bactericidal Activity↗