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Biomedical subjects

C E Edmiston

Publications and source records attributed to C E Edmiston.

At least 19 recordsLinked to original sources
PubMed2002

In vitro evaluation of the antibacterial activity of three different central venous catheters against gram-positive bacteria.

The aim of this study was to evaluate the activity of three different catheters against Staphylococcus aureus ATCC 29213 and the slime-producing Staphylococcus epidermidis ATCC 35984 (RP62A). Three central venous catheters were evaluated: one impregnated with silver sulfadiazine-chlorhexidine, one to which minocycline/rifampin is bonded and a novel one into which silver, platinum and carbon are incorporated. A nonantiseptic catheter was used as the control catheter. One-centimeter trisected pieces of catheter were immersed in phosphate-buffered saline (0.01 mol/l) with 0.25% dextrose and incubated. On days 1, 3, 7, 14 and 21, a 1 ml standardized inoculum was added for 30 min and then replaced with phosphate-buffered saline with 0.25% dextrose. One-third of the samples were immediately sonicated and plated to determine bacterial adherence. The remaining segments were incubated for 4 and 24 h to determine the persistence of bacterial adherence. Bacterial adherence to the catheters impregnated with silver sulfadiazine-chlorhexidine was reduced 91-98% for the first 7 days. Adherence of Staphylococcus aureus to catheters into which silver, platinum and carbon are incorporated was reduced 70% on day 1 and 35% on day 3. Adherence to minocycline/rifampin-bonded catheters was quite variable. There was an 85.6-99.8% reduction in the persistence of bacterial adherence to the three catheters compared to controls. Bacteriostatic and bactericidal studies indicated that the effluents from the catheters impregnated with silver sulfadiazine-chlorhexidine were bactericidal, while effluents from the minocycline/rifampin-bonded catheters were bacteriostatic. The antibacterial activity of the effluents from catheters impregnated with silver sulfadiazine-chlorhexidine dissipated by day 7, while the activity of effluents from the minocycline/rifampin-bonded catheters continued to show activity at day 21. No measurable antibacterial activity was detected in the effluents of the catheters into which silver, platinum and carbon are incorporated. These data suggest that catheters coated with antibiotic/antibacterial agents and the novel catheters that incorporate antiseptic agents have different activities against initial bacterial adherence. All of them, however, effectively prevent bacterial colonization by gram-positive bacteria.

Anti-Bacterial Agents↗
PubMed2001

The importance of beta-lactamase resistance in surgical infections.

Substantial costs are associated with the treatment of nosocomial infections, 2 million cases of which occur annually in the United States. Hospital-acquired, gram-negative infection has become an increasing problem, particularly in the intensive care unit where up to 40% of the most frequently isolated strains of Enterobacteriaceae are resistant to standard beta-lactam antibiotics. Among several mechanisms of acquisition of resistance, beta-lactamase production accounts for a high percentage of treatment failures and relapses. By the end of the 1980s, some 10-30% of all nosocomial infections were caused by type-1 beta-lactamase-producing gram-negative isolates, and Enterobacter species had emerged as a major resistant pathogen. The beta-lactam/beta-lactamase inhibitor combinations, such as ampicillin/sulbactam, represent an innovative approach to the problem of beta-lactamase-mediated resistance. Clinical use of these agents has been associated with low rates of resistance and new data suggest they may have a specific role in controlling the emergence and spread of nosocomial infections.

Cross Infection↗
PubMed2000

Efficacy of preoperative decontamination of the oral cavity.

This two-part study consisted of: (1) a survey to assess current practice patterns, and (2) an experiment designed to assess the results of varying intraoral preparations. A 48 percent response rate was obtained from the survey of the 318 active members of the American Society of Maxillofacial Surgeons. This survey demonstrated that significant controversy continues regarding the efficacy of preoperative decontamination of the oral cavity. This prospective, randomized experimental study of 30 patients (saline, 10; povidone-iodine, 10; no preparation, 10) demonstrates a significant and sustained reduction of both anaerobic and aerobic bacteria after intraoral preparation with povidone-iodine solution but not saline. The patient's age, use of preoperative intravenous cephalosporin, and type and length of procedure did not influence the postoperative bacterial counts. Although none of the patients in this study developed an infection, recommendations are provided for standardized preoperative treatment of the oral cavity.

Antibiotic Prophylaxis↗
PubMed1999

Airborne particulates in the OR environment.

Intraoperative sampling of airborne particulates is rarely performed in the OR environment because of technical difficulties associated with sampling methodologies and because of the common belief that airborne contamination is infrequently associated with surgical site infections (SSIs). In this study, investigators recovered non-viable (i.e., lint) and viable (i.e., microorganisms) particulates during vascular surgery using a personal cascade impactor sampling device. The predominant nonviable particulates recovered during intraoperative sampling were wood pulp fibers from disposable gowns and drapes. Several potential nosocomial pathogens (e.g., Staphylococcus aureus, Staphylococcus epidermidis) and other drug-resistant isolates frequently were recovered from an area adjacent to the surgical field. The widespread presence of airborne particulates during surgery suggests that further studies are warranted to assess the role these particles may play in the development of SSIs or in dissemination of nosocomial pathogens within the OR and hospital environment.

Air Microbiology↗
PubMed1999

Ruthenium red and the bacterial glycocalyx.

Ruthenium red, a promising cationic reagent for electron microscopy (EM), has long been an important tool in histology. The reagent was initially used by botanists as a semispecific stain for pectic substances, but it has gradually been embraced by investigators in microbiology and the animal sciences as a stain for anionic glycosylated polymeric substances. Luft developed a reliable method and demonstrated that ruthenium red was a useful reagent for visualizing ultrastructural detail. Many investigators, using modifications of Luft's approach, have identified numerous applications for this important reagent. Ruthenium red has been used to show the ultrastructural detail of bacterial glycocalyces. Strong, sharp and consistent observations of this ultrastructural component of the bacterial cell have given a better understanding its fibrous anionic matrix. Any variations in staining owing to artifactual alteration of the fine delicate ultrastructural features have been overcome by incorporation of diamine lysine into ruthenium red methods, thus providing flexible processing times under less than ideal laboratory sampling conditions. Ruthenium red has broad utility in the biological sciences, and in combination with lysine, it is an excellent EM stain for enhanced visualization of bacterial glycocalyx from culture or from clinical specimens.

Animals↗
PubMed1998

Superior preservation of the staphylococcal glycocalyx with aldehyde-ruthenium red and select lysine salts using extended fixation times.

The utility of lysine-based aldehyde-ruthenium red fixatives for the preservation and/or staining of the fibrous staphylococcal glycocalyx was improved by substitution of alternative forms of lysine for the free amino form. Paraformaldehyde-glutaraldehyde fixatives containing alternative lysines, with or without ruthenium red, were compared at short 20-minute prefixation times and at extended overnight fixation times. Although inclusion of paraformaldehyde made longer fixation times possible, the length of time for "safe" fixation varied per sample and could not be predicted. All alternative lysine forms permitted fixation of at least 24 hours without sample loss. The L-lysine monohydrochloride or L-lysine acetate forms permitted longer fixation times than the L-lysine free amino form, and they had comparable or better preservation of the staphylococcal glycocalyx. Thus, the usefulness of aldehyde-lysine-based fixatives with minor changes has been enhanced.

Aldehydes↗
PubMed1998

Elimination of intraluminal colonization by antibiotic lock in silicone vascular catheters.

An in vitro model was designed to evaluate the efficacy of instilled antimicrobials to reduce or eliminate intraluminal microbial colonization. Minimal inhibitory concentration and minimal bactericidal concentration activity of appropriate test anti-infectives were determined using standard methodology against clinically derived and reference test strains commonly associated with catheter-related infection. Drug activity was validated by bioassay for the test anti-infectives. Reference and clinical test strains were inoculated to the intraluminal surface of silicone catheter segments and incubated for 30 min, after which the inoculum was replaced with total parenteral nutrition (TPN) solution and reincubated for 12 h. For 7 d, instillation of antibiotic and TPN solution was alternated every 12 h to simulate clinical conditions. On days 1, 4, and 7, catheter segments were rinsed, bisected, and sonicated for quantitative plate count to determine mean microbial counts per centimeter of catheter surface. Catheter segments were also prepared for scanning electron microscopy. A significant decrease in staphylococcal intraluminal colonization after instillation of nafcillin, ceftriaxone, gentamicin, and vancomycin was demonstrated (P < 0.001). Aztreonam, ceftriaxone, and gentamicin completely eliminated gram-negative catheter colonization (P < 0.001). Yeast was eradicated from the internal catheter surface after treatment with amphoteracin B, and fluconazole significantly decreased intraluminal colonization (P < 0.001). Results show a significant decrease in staphylococcal, gram-negative, and fungal intraluminal colonization after instillation of appropriate antimicrobial. In vitro results support early clinical success using this technique. Future studies are warranted to identify optimal drug concentrations and dosing intervals.

Anti-Bacterial Agents↗
PubMed1997

Paraformaldehyde effect on ruthenium red and lysine preservation and staining of the staphylococcal glycocalyx.

The utility of lysine in glutaraldehyde-ruthenium red fixatives for the preservation and/or staining of the fibrous staphylococci glycocalyx was improved by inclusion of paraformaldehyde. Short, 20 min prefixation times for paraformaldehyde-glutaraldehyde fixatives containing lysine, with or without ruthenium red, were compared to an extended overnight fixation. Samples were often lost in fixatives that did not contain paraformaldehyde at extended fixation times hampering the effective use of these fixatives for clinical or environmental applications. Inclusion of paraformaldehyde in the fixation with lysine permitted longer fixation times as well as stabilized the staphylococcal glycocalyx. Thus, the technical usefulness of fixatives employing lysine was significantly improved.

Fixatives↗
PubMed1996

Pharmacodynamics of antimicrobial therapy in surgery.

INTRODUCTION: "Pharmacodynamics" refers to the relationship of drug concentrations in serum or tissues to effects on biologic systems. Concepts used to describe antimicrobial pharmacodynamics include the minimal inhibitory concentration (MIC), the minimal bactericidal concentration (MBC), and serum bactericidal titers (SBT), as well as post-antibiotic effect. METHODS: Pertinent published literature was identified through a MEDLINE search. RESULTS: Aminoglycosides have a concentration-dependent effect on bacteria killing and possess a relatively long postantibiotic effect. Given these characteristics, single-daily dosing, where the total daily dose with a traditional aminoglycoside regimen is given as one dose, may be more efficacious compared with more frequent dosing. For beta-lactam antimicrobials, bacterial killing is related to the duration of time that the free drug concentration exceeds the bacterial MIC. Beta-lactam antimicrobials have been shown to have no, or a short postantibiotic effect. Beta-lactam antimicrobials may be more effective when administered as continuous intravenous infusions. CONCLUSIONS: Pharmacodynamic variation may result from differences in drug sensitivity among individuals and the nature of the interaction between antimicrobials and microorganisms. Proper use of pharmacokinetic and pharmacodynamic principles can result in more effective and less toxic antimicrobial regimens.

Aminoglycosides↗
PubMed1996

Penetration of ciprofloxacin and fleroxacin into biliary tract.

Forty patients with chronic cholecystitis or cholelithiasis were prospectively randomized for therapy with either ciprofloxacin or fleroxacin to study the penetration of these two agents into gallbladder tissue, plasma, and bile. Patients received a 3-day course of ciprofloxacin (500 mg twice a day) or fleroxacin (400 mg once daily) and were subdivided into four groups reflecting intraoperative sample collection at 4, 7, 14, and 25 to 26 h following the last quinolone dose. Mean concentrations in plasma for ciprofloxacin and fleroxacin at 4 and 25 to 26 h postdose were 2.5 and 10 micrograms/ml and 0.3 and 1.8 micrograms/ml, respectively. The concentrations of ciprofloxacin and fleroxacin in bile and gallbladder wall tissue at 25 to 26 h postdose were 4.5 and 8.6 micrograms/ml and 1.2 and 4.4 micrograms/ml, respectively. Both agents demonstrate rapid tissue penetration with persistence at levels appropriate for treatment of biliary pathogens.

Adolescent↗
PubMed1996

Vancomycin resistance: when failure becomes an opportunity for leadership.

OBJECTIVE: To discuss the emergence of the enterococci as significant nosocomial pathogens and reports of glycopeptide resistance as demonstrating the failure of healthcare professionals to limit the clinical impact of these organisms. BACKGROUND: The enterococci have long occupied a peculiar position in medical and surgical patients. A component of the normal gastrointestinal tract, these organisms exhibit little overt pathogenicity in healthy hosts, but are frequently recovered in patients with severe debilitative or immunosuppresive disorders. While the enterococci have always demonstrated intrinsic resistance to a broad range of antiinfective agents, recent findings of moderate to high-level glycopeptide resistance potentially threaten the limited therapeutic options for methicillin-resistant gram-positive cocci. FINDINGS: The emergence and dissemination of vancomycin-resistant enterococci are signs of much greater problems, which include incomplete success of formulary controls, unreliable detection and identification of resistant microorganisms within the hospital environment, and poor fundamental infection control practices by all healthcare professionals. CONCLUSIONS: The Hospital Infection Control Practices. Advisory Committee Recommendations for the Prevention and Spread of Vancomycin Resistance are an important step in resolving these issues through the elements of collegiality and shared leadership.

Anti-Bacterial Agents↗
PubMed1995

Surgical sepsis: constancy of antibiotic susceptibility of causative organisms.

BACKGROUND: It is well documented that antibiotic therapy exerts selective pressure on bacteria. Conversion of bacteria from susceptible to resistant to antibiotics has been observed often during antimicrobial therapy. It has been postulated that human intestinal reservoirs facilitate communication of transposons that can transfer resistance determinants among various bacterial species. METHODS: This study examined the susceptibilities of organisms isolated from infected abdomens to a number of antibiotic agents during a 12-year time interval. Analysis included 1102 isolates recovered from 255 specimens, representing the following genera: Bacteroides, Clostridium, Gemella, Fusobacterium, Peptostreptococcus, Porphyromonas, Prevotella, Enterococcus, Staphylococcus, Streptococcus, Pseudomonas, and Enterobacteriaceae. Strains were tested against beta-lactam agents, beta-lactams in combination with beta-lactamase inhibitors, first, second, and third generation cephalosporins, aminoglycosides, clindamycin, metronidazole, chloramphenicol, and imipenem. RESULTS: The results indicated that during a time period of more than a decade essentially no change occurred in the antibiotic susceptible fraction of all species tested. CONCLUSIONS: Abdominal sepsis is caused by leakage of endogenous intestinal flora. This study suggests that the intestinal flora is not permanently affected by short-term antibiotic therapy and that older antibiotics are appropriate first-line therapeutic agents for community-acquired infections caused by normal intestinal flora.

Abdomen↗
PubMed1995

Treatment of Hickman catheter sepsis using antibiotic lock technique.

Antibiotic lock therapy, an alternative treatment for Hickman catheter sepsis, was evaluated in six recipients of prolonged outpatient intravenous therapy. Twenty-two episodes of catheter sepsis were identified, involving coagulase-negative staphylococci (11), gram-negative bacilli (3), gram-positive bacilli (1), yeast (4), and mixed bacteria or fungi (3). In a select group of patients, treatment was successful 92% of the time.

Anti-Bacterial Agents↗
PubMed1994

In situ replacement of arterial prosthesis infected by bacterial biofilms: long-term follow-up.

PURPOSE: Bacterial biofilm infections of vascular prostheses are characterized by an absence of systemic sepsis, a fluid-filled cavity surrounding the graft, a draining sinus tract, and microorganisms that must be removed from the fabric prosthesis for bacterial culture. METHODS: Since 1987 we have treated 20 infected grafts with prosthetic excision and in situ replacement in 14 men and 6 women. The time from initial graft implantation to diagnosis of graft infection ranged from 3 months to 14 years (mean 4.5 years). The original graft (Dacron-17, polytetrafluoroethylene-3) was an aortobifemoral in 14, axillofemoral femorofemoral in 3, iliofemoral in 2, and femoropopliteal in 1 patient. Presenting symptoms were groin false aneurysm with perigraft fluid in 10, inflammatory mass in 6, and sinus tract in 4. At surgery all unincorporated graft material and the perigraft capsule were excised from a point where the proximal graft was incorporated, including debridement of vessels at the distal anastomosis. Of the 14 aortobifemoral grafts, only the femoral limbs were excised at the initial presentation of biofilm infection. The conduit was replaced with an in situ polytetrafluoroethylene interposition graft, which was covered with a gracilis or sartorius muscle flap when possible. RESULTS: All surgical sites healed, all grafts remained patent, and there was no limb loss. After ultrasonic oscillation of the explanted graft, bacterial cultures recovered coagulase-negative Staphylococcus species in 14, coagulase-positive Staphylococcus species in one, both species in three, with no growth from two specimens. During follow-up, two patients have had clinical involvement in the proximal intraabdominal portion of the graft that had not been previously resected. In all grafts, the in situ replacement graft remained well incorporated. CONCLUSION: In situ graft replacement is effective treatment for biofilm infections of vascular prostheses. Because of the indolent nature of these infections, subsequent infection of previously uninvolved graft segments may be expected.

Bacterial Adhesion↗