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PubMed2001

Antimicrobial peptides isolated from skin secretions of the diploid frog, Xenopus tropicalis (Pipidae).

Seven peptides (XT-1-XT-7) with antimicrobial activity were isolated from norepinephrine-stimulated skin secretions of the diploid clawed frog, Xenopus tropicalis. Structural characterization of the peptides demonstrated that amino acid sequence similarity to antimicrobial peptides previously isolated from Xenopus laevis was low, suggesting that the species are not closely related phylogenetically. Peptides XT-5 and XT-3 are probably the orthologs of X. laevis peptide glycine-leucine amide (PGL(a)) and the N-terminal spacer region of prolevitide, respectively. XT-1, XT-6 and XT-7 show limited structural similarity to the spacer region of X. laevis procaeruleins and the paralogs XT-2 and XT-4 are similar to corresponding regions of proxenopsin. Orthologs of the magainins were not identified. The C-terminally alpha-amidated peptide XT-7 (GLLGPLLKIAAKVGSNLL.NH2) showed the lowest minimum inhibitory concentrations against reference microorganisms (Staphylococcus aureus 5 microM, Escherichia coli 5 microM, and Candida albicans 40 microM) and was also active against clinical isolates of methicillin-resistant S. aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus, Streptococcus group C, Shigella sonnei, Pseudomonas aeruginosa and Enterobacter cloacae. The peptide was, however, hemolytic against human erythrocytes (50% lysis at 70 microM). Circular dichroism studies showed that XT-7 has a random structure in aqueous solution, pH 7.0 but adopts an alpha-helical conformation in the presence of 50% trifluoroethanol. Decreasing the cationicity of XT-7 either by replacement of the C-terminal CONH2 group by COOH or by deletion of the Lys(8) residue produced analogs with greatly (>10-fold) decreased antimicrobial potencies.

Amino Acid Sequence↗

PubMed2003

Characterization of RAP, a quorum sensing activator of Staphylococcus aureus.

Staphylococcus aureus are Gram-positive bacteria and cause diverse serious diseases in humans and animals through the production of toxins. The production of toxins is regulated by quorum sensing mechanisms, where proteins such as RNAIII activating protein (RAP) are secreted by the bacteria and induce virulence. Antibodies to RAP have been shown to protect mice from infection, but the molecular structure of RAP was not known and hindered vaccine development. To characterize RAP, recombinant protein was made and tested for its ability to induce genes important for pathogenesis (agr). In addition, monoclonal antibodies were produced to identify its cellular localization. Results shown here indicate that RAP is a 277-aa protein that is an ortholog of the ribosomal protein L2. Like the native molecule, recombinant RAP activates the production of RNAIII (encoded by agr). Using RAP specific monoclonal antibodies we demonstrate that RAP is continuously secreted and while RAP is expressed also in other bacteria (like Staphylococcus epidermidis, Staphylococcus xylosus and Escherichia coli), it is secreted to the culture medium only by S. aureus. Our results show that the ribosomal protein L2 has an extraribosomal function and that when secreted RAP acts as an autoinducer of virulence to regulate S. aureus pathogenesis.

Adaptor Proteins, Signal Transducing↗

PubMed1986

The nosocomial colonization of T. Bear.

A national effort to reduce nosocomial infections includes a program developed at the National Institutes of Health to encourage handwashing in hospitals and day care centers. The program promotes a symbolic teddy bear (T. Bear) with slogans to remind hospital personnel and patients to practice handwashing. One of the items used is a stuffed toy T. Bear to be dispensed to the hospitalized child. Considering the manner in which children handle stuffed toys, we suspected the T. Bear might serve as a "fomite" for transmission of nosocomial microbes. A prospective study of 39 sterilized T. Bears revealed that all became colonized with bacteria, fungi, or both within 1 week of hospitalization. Hospital acquired organisms cultured from the T. Bear included Staphylococcus epidermidis, Staphylococcus aureus, alpha streptococci, Corynebacterium acnes, Micrococcus sp, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Bacillus sp, and species of Candida, Cryptococcus, Trichosporon, Aspergillus and others. Concomitant cultures of the patients revealed similar isolates. Although the T. Bear handwashing campaign should not be discredited, the promotional toy may pose an unnecessary expense and hazard and should not be used in hospitals or day care centers.

Attitude of Health Personnel↗

PubMed2006

Contamination of disposable tonometer prisms during tonometry.

AIM: Due to the theoretical possibility of prion transmission in applanation tonometry, many ophthalmological units in the United Kingdom now use disposable tonometer prisms. We have investigated the potential for bacterial and viral transmission from the health practitioner to the patient via disposable prisms. METHODS: All staff who perform applanation tonometry at the Sussex Eye Hospital (SEH) received a questionnaire to evaluate if the applanating face of the prism is touched during tonometry and the ease of use of the disposable prism compared to the reusable prisms that were previously used. We then cultured prisms handled by a random sample of staff members for common bacteria. Finally, we constructed a model to investigate the possibility of interpatient adenoviral transmission via disposable tonometer prisms. RESULTS: The questionnaire revealed that almost 50% of the staff admit to touching the applanating face of the tonometer prism prior to applanation. Cultures of the prisms grew a range of bacteria including Staphylococcus epidermidis, Staphylococcus aureus, and Bacillus species. The viral model suggested that adenovirus could be transmitted by applanation tonometry. CONCLUSION: The use of disposable prisms for applanation tonometry may reduce the risk of prion transmission but is not bacteriologically or virologically aseptic. This is a potential infection risk to patients.

Adenoviridae↗

PubMed2001

Evaluation of the BacT/Alert automated blood culture system for detecting bacteria and measuring their growth kinetics in leucodepleted and non-leucodepleted platelet concentrates.

BACKGROUND AND OBJECTIVE: To evaluate the BacT/Alert automated blood culture system for the detection of bacteria in platelet concentrates, and to determine bacterial growth kinetics in leucodepleted and non-leucodepleted units. MATERIALS AND METHODS: Apheresis (Cobe Leucocyte Reduction System [LRS]) and pooled buffy coat-derived (Optipress) platelet concentrates (PCs) were tested. Six organisms were used for spiking the PCs: Clostridium perfringens, Bacillus cereus, Group B Streptococcus, Staphylococcus epidermidis, Staphylococcus aureus and Escherichia coli. Units were inoculated to give a final concentration of approximately equal to 1 and 50 colony-forming units (CFU)/ml. On days 0, 2 and 5, BacT/Alert standard aerobic and anaerobic bottles were inoculated with a 5-ml fill volume and bacteria were enumerated. RESULTS: The BacT/Alert Automated blood culture system gave rapid determination times of spiked units, with all positives detected within 48 h and 98.1% detected within 24 h. In general, as the inoculum concentration increased, the detection time decreased. Rapid growth was obtained with all organisms tested except for B. cereus, which failed to grow on four occasions. Bacterial numbers on day 2 ranged from 10(5) to 10(11) CFU/ml and on day 5 ranged from 10(4) to 10(12) CFU/ml. Growth was not significantly greater in leucodepleted units. CONCLUSIONS: The study confirmed that PCs are an excellent growth medium for bacteria. Rapid and substantial growth was obtained with all organisms under test. Leucodepletion does not appear to enhance bacterial proliferation. The BacT/Alert automated blood culture system could rapidly detect contamination of units. Bacterial screening using an automated blood culture system is therefore a potential option.

Bacteria↗

PubMed2000

Intravascular catheter-related infections: a preventable challenge in the critically ill.

In modem medicine, central venous catheters (CVCs) have a pivotal role in the management of critically ill patients. The most serious complication of effective CVC placement is catheter-related bloodstream infection (CRBSI). Microbial colonization and CRBSI are the byproducts of the interaction of 4 factors: (1) microbial factors (hydrophobicity and exopolysaccharide production), (2) host factors (such protein adhesins as fibrin and fibronectin that attach to the catheter surface), (3) catheter material (hydrophobicity, surface charges, thrombogenicity), and (4) iatrogenic factors (total parenteral nutrition, interleukin-2). The organisms most frequently associated with CRBSI are Staphylococcus epidermidis, Staphylococcus aureus, and Candida spp. CRBSIs were traditionally diagnosed through semiquantitative or quantitative cultures of the catheter tip. However, the diagnosis can be achieved without catheter removal through cultures of blood specimens collected simultaneously though the CVC and a peripheral vein. Currently, the most effective method of preventing a CRBSI is the use of a CVC coated with antimicrobial agents. Intravenous administration of vancomycin for 7 days is adequate for an uncomplicated CRBSI caused by coagulase-negative staphylococci, and at least 10 days of therapy with beta-lactams is required for an uncomplicated infection caused by methicillin-sensitive S. aureus. CRBSI caused by Candida albicans or Candida parapsilosis can be treated with at least 14 days of therapy with fluconazole or amphotericin B. In the case of Candida krusei, only amphotericin B is effective.

Bacteremia↗

PubMed1999

[Bacterial keratitis in patients with and without contact lens anamnesis].

BACKGROUND: The study shows differences between contact lens wearers and patients without history of contact lenses regarding the spectrum of etiological agents in bacterial keratitis. Based on microbiological analysis, there are given recommendations for an optimal initial antibiotic treatment in both groups. MATERIAL AND METHODS: From 1989 to 1997 smears, scrapings and corneal biopsies were taken from 218 patients with bacterial keratitis. The causing pathogens were isolated on directly inoculated culture media and identified by staining and microscopy. The resistance pattern of a total of 275 germs was analysed for different antibiotics. RESULTS: The most frequently isolated germs were Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus spp., Propionibacterium acnes and Pseudomonas aeruginosa. Whereas sensitive gram-positive germs were predominating in contact lens wearers as well as in non-contact lens wearers, multiresistant gram-negative germs could nearly exclusively be isolated from contact lens wearers. Frequently administered antibiotics like aminoglycosides and quinolones are effective in infections caused by Staphylococcus spp., but increasing resistance could be seen to Streptococcus spp. In this case, erythromycin is very sensitive. Gram-negative germs like Pseudomonas aeruginosa are sensitive to quinolones and some aminoglycosides (e.g. tobramycin). CONCLUSION: In contact lens wearers, more aggressive germs have to be considered than in non-contact lens wearers. In such cases, frequently administered antibiotics like amino-glycosides are not effective. To cover problematic gram-negative germs we recommend the application of quinolones alternating with erythromycin. The latter one is more effective than quinolones and aminoglycosides in case of Streptococcus spp. co-involvement.

Adult↗

PubMedDate not supplied

Nosocomial bacteremia in a large Spanish teaching hospital: analysis of factors influencing prognosis.

Five hundred forty-three episodes of nosocomial bacteremia were prospectively followed in a large Spanish university hospital. The commonest isolates were Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida species. The most frequent sources of infection were intravenous lines, urinary tract, and lower respiratory tract. Overall mortality was 18%. A step-forward logistic regression analysis defined eight variables independently influencing the outcome: shock, underlying rapidly fatal disease, high-risk source of bacteremia (intraabdominal, lower respiratory tract, or not identified), age more than 70 years, hospitalization in intensive care or medical units, inappropriate antibiotic treatment, infection due to a high-risk microorganism (P. aeruginosa, Serratia marcescens, Klebsiella, Bacteroides, or Candida), and development of septic metastasis. The identification of those factors independently influencing the outcome and their possible modification may represent a further step in the control of nosocomial bacteremia by improving its prognosis.

Adult↗

PubMed2002

In vitro activity of quinupristin/dalfopristin, linezolid, telithromycin and comparator antimicrobial agents against 13 species of coagulase-negative staphylococci.

OBJECTIVES: To determine in vitro susceptibilities of a large series of speciated coagulase-negative staphylococci (CNS) against three new antibiotics, linezolid, quinupristin/dalfopristin and telithromycin. METHODS: Susceptibilities to three new antibiotics and oxacillin, vancomycin, clindamycin and erythromycin were determined by the agar dilution method, as described by the NCCLS. RESULTS: Resistance to linezolid was not observed in any isolates, although MIC90 values varied between species. Fifteen of 658 (2.3%) isolates were resistant to quinupristin/dalfopristin, but < 1% of the clinically most important isolates of Staphylococcus epidermidis, Staphylococcus haemolyticus and Staphylococcus hominis demonstrated resistance to this agent. Susceptibility to clindamycin correlated with susceptibility to quinupristin/dalfopristin; however, resistance to clindamycin did not predict quinupristin/dalfopristin resistance. Telithromycin was the least active of the new agents tested, showing activity similar to that of clindamycin. Susceptibility and resistance to clindamycin were predictive of susceptibility and resistance to telithromycin. CONCLUSION: Clindamycin susceptibility can be used as a surrogate marker for susceptibility to quinupristin/dalfopristin and telithromycin. Quinupristin/dalfopristin and linezolid show good activity against both mecA-positive and -negative CNS.

Acetamides↗

PubMed1997

Septicaemia in paediatric cancer patients: a 5-year surveillance study in university hospital, Kuala Lumpur, Malaysia.

Infectious complications are the major cause of morbidity and mortality in children with malignancy. Empirical antimicrobial therapy in the management of fever of unknown origin should be tailored to local bacteriological data and antibiotic sensitivity patterns. Five-hundred-and-fifty-nine cases of culture-proven septicaemia occurring in pediatric cancer patients between 1990 and 1994 were retrospectively analysed and compared with a similar study done in our centre between 1976 and 1979. A wide spectrum of organisms was isolated. Staphylococcus epidermidis, Staphylococcus aureus, and Klebsiella pneumoniae were the most common and consistent bacteria isolated during the 5 year period. More than 70 per cent of the staphylococci were sensitive to methicillin and universally sensitive to vancomycin. However, a worrying trend of ceftazidime-resistance amongst gram-negative organisms was found. In these situations, the use of imipenem is recommended as resistance to this antimicrobial agent was exceedingly rare.

Bacteria↗

PubMed2001

Implications of 2,457 consecutive surgical infections entering year 2000.

OBJECTIVE: To assess the demographics and characteristics of infections in surgical patients to define areas that deserve emphasis in surgical education. SUMMARY BACKGROUND DATA: As a result of evolving technology and diseases, the complexity of diagnosing and treating infections has increased during the past three decades for all patients, including those treated primarily by surgeons. No comprehensive analysis of these conditions in a single surgical cohort has been recently published. METHODS: The authors conducted a prospective, observational study of all infections occurring on the general and trauma surgery services at a single university hospital during a 3.5-year period. RESULTS: The authors identified 2,457 infections: 608 community-acquired, 1,053 occurring on the wards, and 796 occurring in the intensive care unit. Although dependent on patient location, the most common sites were abdomen, lung, and wound; the most common isolates were Staphylococcus epidermidis, Staphylococcus aureus, and Candida albicans; and the most commonly used antibiotics were ciprofloxacin, vancomycin, and metronidazole. The overall death rate was 13%, ranging from 5% after community-acquired infections to 25% after infections acquired in the intensive care unit. CONCLUSIONS: Most infections treated by surgeons are hospital-acquired. Infections with gram-positive cocci and fungi are common, with pulmonary infections becoming more common. Fluoroquinolones have become important therapeutic agents. Depending on the type of practice, these data should be helpful to direct educational efforts so that surgeons can remain knowledgeable and active in the nonsurgical care of their patients.

Abdomen↗

PubMed2001

Nosocomial infections in the neonatal intensive care unit.

Nosocomial infections are significant causes of morbidity and mortality in patients who require newborn intensive care. The most common bacterial pathogens are Gram-positive bacteria, including Staphylococcus epidermidis, Staphylococcus aureus, and Enterococcus species. Gram-negative enteric bacilli and Gram-negative environmental bacteria are involved in outbreaks and occasional cases of nosocomial infection. The incidence of fungal infection has increased over the past 10 years; fungemia is the most commonly recognized infection. Surveillance for nosocomial infection is essential to identify outbreaks and detect unsuspected reservoirs of pathogens. A variety of molecular techniques can be used to determine the genetic relatedness of pathogens. Prevention of infection requires the identification of contaminated equipment, education regarding infection control methods including hand washing, and the judicious use of antimicrobial agents.

Cross Infection↗

PubMed1998

Reconstituted recombinant factor VIII can be safely infused continuously for at least three days: it is a poor microbial growth medium.

Reconstituted recombinant factor VIII (FVIIIrec) loses little biologic activity at room temperature for up to seven days and continuous infusion is convenient, effective hemostatically and requires less FVIIIrec concentrate than treatment by conventional bolus injections. However, the potential for bacterial contamination, with proliferation to high levels that can cause bacteremia, is a concern with continuous infusion. We studied the growth properties at 4, 25 and 35 degrees C in reconstituted FVIIIrec (Kogenate) and at 25 degrees C in 5% dextrose in water (D5%W) of three isolates each of Staphylococcus epidermidis, Staphylococcus aureus, Enterobacter cloacae, Klebsiella oxytoca, Serratia marcescens, Acinetobacter calcoaceticus, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Burkholderia cepacia, Flavobacterium spp. and Candida albicans, species most likely to contaminate infusate during preparation or administration and which have been implicated in more than 95% of all outbreaks and sporadic cases of nosocomial bloodstream infection traced to contaminated admixtures, biologic agents or medications administered parenterally. Reconstituted FVIIIrec allowed growth of only three species at 25 degrees C and 35 degrees C: S. marcescens, S. maltophilia and P. aeruginosa; logarithmic growth appeared only after 24-48 h. D5%W allowed growth of two gram-negative species, S. marcescens and B. cepacia. We conclude that reconstituted FVIIIrec (Kogenate) is a poor growth medium for most nosocomial pathogens, comparable with D5%W. If reconstituted aseptically, continuous infusion of reconstituted FVIIIrec should be safe, and it should not be necessary to replace the container or tubing more frequently than every 3 days, an administration schedule that can provide effective hemostasis at lower cost.

Bacteremia↗

PubMedDate not supplied

Activation and control of complement, inflammation, and infection associated with the use of biomedical polymers.

It is generally acknowledged that artificial biomaterials are much less immunologically active than transplants or tissue derived biomaterials. However, activation of both the coagulation cascade and the complement system is a common occurrence when human blood is exposed to biomaterial surfaces during extracorporeal procedures, such as renal hemodialysis or cardiopulmonary bypass. Both individual and collective activation of these cascades often produce local and systemic effects. A number of complement activation products function as the mediators of inflammation. They serve as ligands for specific receptors on polymorphonuclear leukocytes, monocytes, macrophages, mast cells, and other cells. Such an interaction leads to induction of cellular responses in adhered cells, including release of oxidative products, lysosomal enzymes, or both, which often contribute to a number of pathologic conditions. Most pathogens invading the human body are attacked by the immune system directly following entry, especially when they are in contact with blood. However, bacteria and parasites have developed a large number of specific strategies to overcome immune defense among others by avoiding either recognition or eradication by complement. In this aspect, of concern are several microorganisms responsible for formation of antibiotic resistant biofilms on biomaterial surfaces, namely Staphylococcus epidermidis, Staphylococcus aureus, and Pseudomonas aeruginosa.

Biocompatible Materials↗

PubMed2006

Unusual aerobic and anaerobic bacteria associated with prosthetic joint infections.

The association of certain microorganisms, such as Staphylococcus epidermidis, Staphylococcus aureus, and beta-hemolytic streptococci, with prosthetic joint infection (PJI) has been recognized for many years. To our knowledge, a systematic review of the presentation and management of less commonly encountered species of coagulase-negative staphylococci, nutritional-variant streptococci, aerobic non-spore and spore forming Gram-positive or anaerobic bacteria is not available. We therefore sought to provide a comprehensive literature review of PJI due to these microorganisms that will provide a valuable and quick reference for clinicians caring for these patients. We conducted a Medline search of all case reports and case series of PJI due to unusual aerobic and anaerobic bacteria. The presentation, surgical, and medical management strategies were reviewed. Appropriate medical and surgical management of such infections is complex and evolving as newer diagnostic tests, surgical techniques and antimicrobials become available. Management of patients with these infections requires close collaboration between the orthopaedic surgeon, infectious disease specialist and microbiology laboratory.

Bacteria, Aerobic↗

PubMed1992

Quantitative separation of bacteria in saline solution using lanthanide Er(III) and a magnetic field.

A trivalent lanthanide ion, erbium (Er3+), has been used in combination with a magnetic separation technique to isolate seven bacterial species from suspensions in 0.9% saline. Erbium has an exceptionally high atomic magnetic moment of 9.3 Bohr magnetons, and following addition as ErCl3 (final concentration 5 mM) to bacterial suspensions, it imparts the magnetic moment to the bacterial cells by ionic binding to the cell surface. Strains of Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus epidermidis, Staphylococcus saprophyticus and Enterococcus faecalis were obtained from the Quality Control Depository of The Cleveland Clinic Foundation, Cleveland, Ohio, USA as suspensions in 0.9% NaCl, in concentrations ranging from 10(2) to 10(8) c.f.u. ml-1. Bacteria were separated from solution inside a capillary flow cell exposed to a highly non-homogeneous magnetic field (maximum field intensity was 0.4 T) and quantified by a light scattering method. The quantity of cellular deposition in the magnetic field was correlated with the initial concentration of cells in the suspension, expressed in c.f.u. ml-1, and sample volume (1.5 and 3.0 ml), sample pH (prior to ErCl3 addition), affinity to Gram stain (negative vs positive) and species.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriological Techniques↗

PubMed1997

Identification of staphylococcal and streptococcal causes of bovine mastitis using 16S-23S rRNA spacer regions.

Bovine mastitis is caused mainly by certain Staphylococcus and Streptococcus species. The sequences of the 16S-23S rRNA spacer regions were determined for the nine species which cause mastitis: Staphylococcus aureus, Staphylococcus chromogenes, Staphylococcus epidermidis, Staphylococcus hyicus, Staphylococcus simulans, Staphylococcus xylosus, Streptococcus agalactiae, Streptococcus dysgalactiae and Streptococcus uberis. Significant variation was found between the spacer sequences of different species with the lengths of the spacers varying from 240 to 461 bp. Between genera the spacers shared only short conserved regions (8-9 bp) and within genera the sequence identities varied from 53 to 85%. This variation made it possible to construct specific primer pairs for these species and genera. The specificities of these primers were tested with 25 bacterial species and 51 isolates from cattle with clinical mastitis. The DNA-based identification of the mastitis species was mostly successful.

Animals↗

PubMed2004

Evaluation of phenotypic methods for methicillin resistance characterization in coagulase-negative staphylococci (CNS).

Coagulase-negative staphylococci (CNS) are the major cause of nosocomial infections. Methicillin-resistant strains are particularly important because they narrow therapeutic options. Detecting methicillin resistance among CNS has been a challenge for years. The objective of this study was to determine the accuracy of an agar screening test (0.6 and 4 microg oxacillin ml(-1)), disc diffusion and the automated MicroScan system to characterize methicillin resistance among CNS. One hundred and seventy five strains were analysed: 41.1 % Staphylococcus epidermidis and 59.9 % other species; 69.1 % were mecA-positive. The results showed that the methods have optimal correlation with the detection of mecA gene for S. epidermidis, Staphylococcus hominis and Staphylococcus haemolyticus. However, accuracy of the tests is impaired when less common species are analysed. The only 100 % accurate test was agar screening with 4 microg oxacillin ml(-1).

Anti-Bacterial Agents↗