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Surface-immobilized polyethylene oxide for bacterial repellence.

Polyethylene terephthalate films were surface-modified with polyethylene oxide (18,500 g/mol) using a solution technique described previously. These films were investigated for their resistance to bacterial adhesion. Three bacterial strains most commonly associated with implant infections, Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa, were cultured in tryptic soya broth, human plasma and human serum on the polymeric substrates. Significant reductions (between 70 and 95%) in adherent bacteria were observed on the polyethylene oxide-modified substrates compared to the untreated control polyethylene terephthalate. Surface modification with polyethylene oxide may reduce the risk of implant-associated infections. Plasma fibrinogen was observed to play an important role in the adhesion of all three of these species on both the polyethylene oxide-modified and control polyethylene terephthalate materials.

Bacterial Adhesion↗

A comparison of the antibacterial activity of levobupivacaine vs. bupivacaine: an in vitro study with bacteria implicated in epidural infection.

The purpose of the study was to compare the antibacterial activity of bupivacaine with levobupivacaine against a range of bacteria implicated in epidural infection to determine whether any differences existed between the two drugs. Concentrations of 0.125%, 0.25% and 0.5% bupivacaine and levobupivacaine were inoculated with suspensions of either Staphylococcus epidermidis, Staphylococcus aureus or Enterococcus faecalis. After incubation, the mixtures were plated onto blood agar and colony counts were recorded after a further period of incubation. The minimum bactericidal concentration of local anaesthetic against the three bacteria studied was found to be 0.25% for bupivacaine and 0.5% for levobupivacaine showing racemic bupivacaine to have a more potent antibacterial action than levobupivacaine. This finding suggests that the dextrobupivacaine isomer of racemic bupivacaine has a more potent antibacterial action than the levobupivacaine isomer.

Anesthesia, Epidural↗

Antibacterial activity of quinolones against coagulase-negative staphylococci and the quinolone resistance-determining region of the gyrA genes from six species.

Antibacterial activity of quinolones against three species of coagulase-negative staphylococci was investigated. Tosufloxacin and sparfloxacin exhibited potent activities against Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus saprophyticus compared with other quinolones tested. From the analysis of the DNA sequence in the quinolone resistance-determining region (QRDR), greater than 80% homology was recognized in coagulase-negative staphylococci. A series residue was conserved in all six species at the position corresponding to position 84 in Staphylococcus aureus.

Anti-Infective Agents↗

Intra-abdominal sepsis after hepatic resection.

One hundred and thirty hepatic resections performed over an 8-year period were reviewed for evidence of postoperative intra-abdominal sepsis. Of 126 patients who survived for more than 24 hours after operation, 36 developed culture positive intra-abdominal collections (28.6%). Significant independent variables associated with the development of intra-abdominal sepsis were diagnoses of trauma or cholangiocarcinoma, and the need for reoperation to control hemorrhage during the postoperative period. Before 1984, infected fluid collections were treated predominantly by operative drainage, but this has largely been replaced by percutaneous methods, which have proven effective in most cases. Eighteen (50%) of the infections were caused by a mixed bacterial culture, with Streptococcus faecalis, Staphylococcus epidermidis, Staphylococcus aureus and Escherichia coli being the most common isolates. Six patients with clinical signs of sepsis had a sterile fluid collection drained with complete relief of symptoms. This review suggests that intra-abdominal sepsis is a frequent complication after hepatic resection, and can often be managed successfully by nonoperative percutaneous drainage.

Abdomen↗

Disinfecting agents for removing adherent bacteria from orthopaedic hardware.

This investigation seeks to determine whether surfactants or detergents can be used to clean and disinfect orthopaedic wounds with implanted hardware. Thus, a stepwise investigation of biocompatible surfactants and detergents was performed to identify an irrigation agent for disinfecting orthopaedic wounds. Bacterial adhesions assays, irrigation studies, and bactericidal assays determined that benzalkonium chloride showed the greatest efficacy. Testing involved stainless steel screws colonized with a preformed biofilm of Staphylococcus epidermidis, Staphylococcus aureus, or Pseudomonas aeruginosa, which were immersed in benzalkonium chloride solutions for various time intervals under static conditions. After 10 minutes, benzalkonium chloride achieved a minimum 4 log kill (10,000-fold) for all 3 strains of bacteria. Additional studies demonstrated that the high mechanical energy of jet irrigation improved the disinfecting properties of this agent. With jet lavage, both 1:1000 and 1:5000 concentrations of benzalkonium chloride achieved a minimum 2 log kill (100-fold) for all 3 bacteria. The results or this study suggest that at tissue compatible concentrations, benzalkonium chloride has significant disinfection properties for in vitro colonized orthopaedic devices, and these properties may be enhanced via jet lavage.

Anti-Infective Agents, Local↗

In vivo standardization of cutaneous bactericidal activity of antiseptics by using monoxenic hairless mice.

This study was designed to investigate the bactericidal activities of antiseptics on the cutaneous flora of hairless mice monoxenic to Staphylococcus epidermidis, Staphylococcus aureus, or Pseudomonas aeruginosa in vivo. A standardized method for testing such antiseptics to compare their bactericidal effectiveness in humans in described. Seven antiseptics belonging to seven different chemical groups (iodine derivatives, alcohols, mercury compounds, quaternary ammonium salts, biguanides, phenols, and carbanilides) were used as recommended by the manufacturers (conditions of contact or prolonged contact time followed by washing with distilled water). Germfree hairless mice were infected with various bacterial strains by gastric intubation, producing levels of about 10(3) CFU/cm2 of skin. The antiseptic under test was placed on the right or left side of the ventral region. The contralateral side served as a control. In order to standardize the method, a number of crucial parameters were carefully controlled: the amount of antiseptic applied, the area of skin treated, the duration of treatment, and the washing procedure. Skin samples were obtained by cutaneous biopsy, which effectively removed all the bacteria along with the sample. The bacterial populations were counted before and after application of the antiseptic. Reductions of between 0.5 and 1.9 log units were obtained; these are comparable to those observed in humans. The standardization of our procedure and the use of animals with a strictly controlled flora eliminated much of the variability and sources of error inherent in human studies. This model could be of value for the study of resistant bacterial strains responsible for nosocomial infections and for investigations of damaged skin.

Animals↗

Polyamino acid enhancement of bacterial phagocytosis by human polymorphonuclear leukocytes and peritoneal macrophages.

Cationic polyamino acids are known to enhance a variety of cell-cell interactions by virtue of their ability to alter electrostatic forces of cell surfaces. In this study, the effect of polyamino acids on phagocytosis of 3H-labeled bacteria by human polymorphonuclear leukocytes (PMNs) and peritoneal macrophages was investigated. Negatively charged and neutral polyamino acids did not influence phagocytosis of unopsonized Staphylococcus epidermidis, whereas protamine, poly-L-arginine, and poly-L-lysine stimulated phagocytosis in a dose-dependent manner. At 50 micrograms/ml, greater than 30% uptake by PMNs was seen with each of these cationic polyamino acids. Although cationic polyamino acids promoted PMN and peritoneal macrophage phagocytosis of unopsonized S. epidermidis, Staphylococcus aureus M (encapsulated) and M variant (unencapsulated), and Escherichia coli J5, little effect was seen with the parent E. coli O111:B4 or a serotype O222:H16 strain. Pretreatment of bacteria and phagocytes separately demonstrated that the phagocytosis-promoting property of polyamino acids is manifest predominantly on the bacteria. Bacteria pretreated with cationic polyamino acids also elicited a PMN chemiluminescent response, and PMN-associated bacteria were killed, as determined by a fluorochrome microassay. Thus, cationic polyamino acids promote the phagocytosis and killing of many but not all bacterial strains, and in this respect polyamino acids function as opsonins.

Escherichia coli↗

Low-power microwave disinfection of soft contact lenses.

PURPOSE: To evaluate the effectiveness of low-power microwave irradiation on the disinfection of contaminated contact lenses. METHODS: We infected 24 soft contact lenses with Staphylococcus epidermidis, Staphylococcus aureus, and Pseudomonas aeruginosa. Each contact lens was placed into a vial containing 10 mL of contaminated, non-preserved saline. Each vial was then exposed to 2, 4, 6, 9, 12, 15, or 18 minutes of microwave irradiation in an oven (2,450 MHz 600W) set at 10% power. RESULTS: We found all contact lenses to be disinfected after 15 minutes of exposure. All lenses remained hydrated and revealed no apparent damage when examined under the slit-lamp biomicroscope. CONCLUSIONS: Low level microwaving in a home microwave oven can result in effective and non-damaging disinfection of soft contact lenses.

Contact Lenses, Hydrophilic↗

[Studies on the growth and reproduction of bacterial communities on structural materials of the international space station].

Probability of microbial growth and reproduction on the ISS interior and equipment materials varying in chemical composition was studied with the strains of Bacillus subtilis, Staphylococcus epidermidis, Staphylococcus saprophyticus, Pseudomonas putida etc. sampled from the ISS environment. Controls were ground reference strains of same bacterial species. Based on our results, some of the microorganisms are able to survive and proliferate on structural materials; the ability was greater in space isolates as compared with their ground analogs. The greatest ability to grow and proliferate on materials was demonstrated by Bacillus subtilis.

Bacillus subtilis↗

In vitro adherence of bacteria to sutures in cardiac surgery.

The adherence of bacteria to sutures used in cardiac surgery was studied by in vitro quantitative determination with [3H]-leucine-labeled Staphylococcus epidermidis, Staphylococcus aureus and Streptococcus sanguis. The adherence per unit area for staphylococci was least for monofilament polypropylene (Prolene), 3 times higher (p less than 0.05) for braided polyester (Mersiline) and greatest (10 times, p less than 0.005) for braided polyester sutures coated with polybutylate (Ethibond). Mean values for the adherence of streptococci were low for all the sutures. Sutures pretreated with human plasma showed a 12-37% increase in bacterial adherence. The cell surface hydrophobicity, surface charge and the haemagglutinating property of bacteria did not correlate with their adherence property. In view of these observations, it is suggested that: (a) the preferential adherence of staphylococci to intra-cardiac sutures may be one of the explanations for its being the commonest cause of early prosthetic valve endocarditis, (b) there is a need for a careful selection of sutures used in cardiac surgery and (c) the described in vitro assay for bacterial adherence may be used for monitoring the development of better designed sutures and the effect of incorporation of antibiotics in the sutures.

Bacterial Adhesion↗

The infected hip after total hip arthroplasty.

We studied the cases of fifty-two patients with an infection at the site of a prosthetic total hip replacement, and are reporting the significant clinical features, infecting organisms, methods of treatment, and results at long-term follow-up. Forty-eight per cent of the hips had had an operation prior to the index arthroplasty, and 42 per cent had a wound complication. All patients had pain in the infected hip, but only 54 per cent had an erythrocyte sedimentation rate of more than thirty millimeters per hour, 44 per cent had fever, and 15 per cent had leukocytosis. In 88 per cent of the patients a single organism was grown on culture, and Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli were present in about 75 per cent. When antibiotic therapy alone was the initial treatment, the infection was eradicated in only one patient. Excisional arthroplasty was the definitive surgical procedure in thirty-three patients and the infection was eradicated in twenty-seven of them, but the clinical result was satisfactory in only twenty. Of ten patients who had a true Girdlestone arthroplasty, none had recurrence of the infection and all had a clinically satisfactory outcome.

Adult↗

[Chlorhexidine digluconate/chlorocresol combination. In vitro study of interactions observed against potential cutaneous strains].

The interaction type of chlorhexidine digluconate/chlorocresol association (foaming solution DC 102/1, Laboratoires Pierre Fabre Médicament) have been studied according to the chess-board method, on microplate, by determining MBC (Minimal Bactericidal Concentrations) (or MFC (Minimal Fungicidal Concentrations)) adjusted to T 72-150 AFNOR norm (dilution-neutralization, contact 5 mn) and computation of FBC (or FFC) Index. Trials were carried out against 18 hospital strains (Staphylococcus epidermidis, Staphylococcus aureus, Propionibacterium acnes, Candida albicans) and against 4 strains of the AF-NOR norm. MBC of chlorhexidine, against Staphylococci were included between 6.25 and 25 micrograms/ml, and between 25 and 200 micrograms/ml against the others strains. MBC of chlorocresol were included between 800 and 3,200 micrograms/ml. Against the 22 tested strains, 18 synergistic interactions (FBC Index < or = 0.75) were observed, with 4 to 8 reducing factor for chlorhexidine, and > or = 2 for chlorocresol. No antagonism was noted (maximal FBC Index = 1).

Candida albicans↗

Keratinolytic activity of cutaneous and oral bacteria.

A test was developed to measure the keratinolytic activity of cutaneous and oral bacteria. Keratin, labeled with fluorescein isothiocyanate, was used in a phosphate buffer (pH 7.2) with 1 mM dithiothreitol. The degradation of keratin was estimated by measuring the fluorescence of the degradation products in the supernatant of the reaction mixtures in a luminescence spectrometer. Several oral and cutaneous bacteria were investigated: Bacteroides gingivalis, Bacteroides intermedius, Treponema denticola, Actinomyces odontolyticus, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus saprophyticus, Brevibacterium epidermidis, Brevibacterium lines, Corynebacterium glutamicum, Corynebacterium minutissimum, Corynebacterium ovis, and Rhodococcus equi. The dermatophyte Trichophyton rubrum was used as a control organism. The test offered a simple and quantitative method for the estimation of keratin degradation and enabled us to show keratinolytic activity in Trichophyton rubrum, S. epidermidis, S. haemolyticus, B. linens, B. epidermidis, Bacteroides gingivalis, and Treponema denticola. The keratinolytic activity was cell bound and heat sensitive. The presence of dithiothreitol stimulated the degradation of keratin to mainly high-molecular-weight products.

Bacteria↗

Activity of antimicrobial-impregnated silicone tissue expanders.

Because bacterial colonization of medical devices may result in clinical infection, it is conceivable that antimicrobial impregnation of tissue expanders may reduce the rate of infection. The objective of this in vitro study was to examine the spectrum, durability, and shelf-life antimicrobial activity of minocycline/rifampin-impregnated silicone tissue expander shells. The impregnated devices exhibited zones of inhibition at baseline against Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli. The impregnated devices exhibited strong residual activity against S. epidermidis and S. aureus after suspension in serum at 37 degrees C for 4 weeks. There was no significant decrease in the size of zones of inhibition after storing the impregnated devices at room temperature for 1 year. These results indicate that minocycline/rifampin-impregnated tissue expander shells provide broad-spectrum and durable antimicrobial activity and that the shelf-life antimicrobial activity exceeds 1 year. These findings prompt future exploration of the anti-infective efficacy of these antimicrobial-impregnated devices.

Anti-Bacterial Agents↗

Effect of chlorhexidine 0.5% on the hand bacterial flora.

The effects of cleaning the dorsal hand with chlorhexidine 0.5% in spirit was evaluated by bacteriological study in 45 adult patients. In the absence of cleaning it was found that the prevalent microorganisms were Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus viridans and Enterobacteriaceae. Cleaning the hand with chlorhexidine 0.5% eliminated all bacteria except S. epidermidis and S. aureus. In both instances, the culture results showed that the microorganisms were present in very low growth density.

Adult↗

[Bacterial interference with skin colonization in germfree hairless mice].

Bacterial colonization of the digestive tract and the skin was studied over a 3-week period in a group of 10 germfree HRS mice using Staphylococcus epidermidis, Staphylococcus aureus, and Pseudomonas aeruginosa. Sequential utilization of two strains allowed us to carry out six assays and to show the presence of interference phenomena during colonization of the skin. When P. aeruginosa was given after challenge with S. aureus or S. epidermidis, it did not colonize the skin. If the first challenge was done with P. aeruginosa, this bacteria was eliminated within 10 days by S. aureus and S. epidermidis on the skin, but it succeeded in colonizing the digestive tract. When the first challenge was done with S. aureus, colonization of the skin and the digestive tract with S. epidermidis was prevented, whereas these two species were found in association when S. aureus was given in second place. None of the in vitro assays (mixed culture, bacteriocin production, adherence inhibition, antimicrobial activity) could explain the in vivo observations.

Animals↗

In vitro bacterial adherence to ventriculoperitoneal shunts.

Bacterial adherence to medical devices has been recognized as an important initial step in the infectious process, but it has not been fully elucidated regarding ventriculoperitoneal (VP) shunts. The aim of the present study was to quantitatively determine the adherence in vitro of bacteria known to cause VP shunt infections and to identify factors affecting the process. Clinical isolates studied included Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli. Adherence was examined quantitatively per square centimeter, visualized by electron microscopy and related to slime production and hydrophobicity. Although all four strains adhered to VP shunts, there were marked differences, with S. epidermidis and S. aureus showing the highest adherence (67.0 x 10(3) and 15.2 x 10(3) bacteria/cm(2), respectively). Factors affecting adherence included incubation time and temperature, bacterial concentration, device material (lower for silicone than Teflon), slime production and hydrophobicity. These data might be helpful for devising novel strategies to reduce VP shunt infections.

Bacterial Adhesion↗

[Pathogenic properties of coagulase-negative staphylococci in experimental infections].

The frequency of persistence of three Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus saprophyticus strains, respectively, was studied in BALB/c mice at the 10th day of intraperitoneal (ip) challenge. 245 out of 416 mice survived after infections with four bacterial suspensions of different colony forming units (CFU) of each strain. Staphylococci persisted in 61 mice (24,9%). The main sites of persistence were the kidneys, while cocci were rarely isolated from the spleen and the liver. S. epidermidis persisted with a significantly higher rate than the other two species, because S. epidermidis in 28,8%, S. haemolyticus in 4,9%, and S. saprophyticus in 3,6% were reisolated from the organs of the respective infected and surviving animals. The organ persistence was proportional to the amount of bacteria injected. The persistence resulted in subacute microabscesses in the organs. Reisolates of persisting bacteria remained stable in phenotype and genotype concerning antibiotic resistance patterns and biochemical activities for the taxonomic implication, whereas cell surface properties characterizable with phage types altered considerably during persistence. It is concluded that cocci of all three Staphylococcus species are invasive and can persist to a certain extent in the organs of animals with normal immune system, too, after artificial inoculation into the peritoneum i. e. to the serosal surfaces.

Animals↗