Central line infections

Persistent bacterial infections, antibiotic tolerance, and the oxidative stress response

Certain bacterial pathogens are able to evade the host immune system and persist within the human host. The consequences of persistent bacterial infections potentially include increased morbidity and mortality from the infection itself as well as an increased risk of dissemination of disease. Eradication of persistent infections is difficult, often requiring prolonged or repeated courses of antibiotics. During persistent infections, a population or subpopulation of bacteria exists that is refractory to traditional antibiotics, possibly in a non-replicating or metabolically altered state. This review highlights the clinical significance of persistent infections and discusses different in vitro models used to investigate the altered physiology of bacteria during persistent infections. We specifically focus on recent work establishing increased protection against oxidative stress as a key element of the altered physiologic state across different in vitro models and pathogens.

Clinical Manifestations of 6 Cases of Septic Pulmonary Embolism at Increased Risk Recently

Objectives The aim of this study was to investigate the clinico-radiologic features and microbiologic data of patients with SPE in a tertiary care hospital in Busan. Methods We retrospectively analyzed clinical and radiologic features of 6 cases with septic pulmonary embolism that occurred from March 2009 to March 2011 in Dong-A university medical center. Results The mean age of the study population was 58 years, and two men and four women were included. Clinical symptoms included general weakness (5 patients), febrile sensation (4 patients) and pleuritic chest pain (2 patients). Underlying conditions were chemoport infection (4 patients), dental abscess (1 patients), and cellulitis of hip (1 patient). Chest computed tomography revealed bilateral multiple nodular opacities in most patients, and cavitation, central necrosis, feeding vessels were identified. All patients received parenteral antimicrobial therapy with or without central catheter removal, drainage of the extrapulmonary infection. Causative organisms were Pseudomonas aeruginosa (2 patients), Candida albicans (1 patient), Bacillus species (1 patient), and Klebsiella pneumonia (1 patient). Conclusions Clinical and radiologic features of septic pulmonary embolism were various and nonspecific. The diagnosis was usually suggested by the presence of a predisposing factor of septic pulmonary embolism and CT findings of bilateral multiple nodular opacities in patients with infectious signs and symptoms. Most important underlying condition was intravascular device infection.

In vitro antiseptic properties of an ammonium compound combined with denture base acrylic resin

BACKGROUND

Denture base acrylic resin is easily colonised by oral endogenous bacteria and Candida spp., and eventually by extra-oral species such as Staphylococcus spp., Pseudomonadaceae or members of Enterobacteriaceae. This microbial reservoir can be responsive for denture related stomatitis and aspiration pneumonia, a life-threatening infection especially in geriatric patients. However, the oral and denture hygiene of dependent elderly individuals is extremely poor.

OBJECTIVE

This in vitro study aimed to determine the per cent of a quaternary ammonium compound heat-polymerised in acrylic resin necessary to obtain denture base displaying antiseptic properties.

DESIGN

Acrylic resin discs containing 2-50% ammonium polymer (Poly 202063A; 0% control) were soaked in artificial saliva for 4 weeks. Resin discs were incubated for 24 hours with Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa [37 degrees C, brain-heart infusion (BHI) broth and phosphate-buffered saline (PBS) buffer] and Candida albicans (30 degrees C, Schaedler broth), in 15 ml (168 discs) and 600 microl (168 discs) of inoculum. Microbial growth was verified at t 0 hours and t 24 hours. Data were recorded as the mean of three colony forming unit (CFU) numerations. The borderline of antimicrobial effect was determined at 0.1% viable cells.

RESULTS

In 600 microl of PBS inoculum, resin specimens had a bactericidal effect (E. coli and S. aureus: 2%; P. aeruginosa: 10%) and a fungicidal effect (C. albicans: 50%). Long-term stability and toxicity in vivo studies are now required.

CONCLUSION

A 2% quaternary ammonium compound polymerised with a denture acrylic resin displayed antiseptic properties after a 4-week soaking period in artificial saliva. Such antiseptic denture base could help geriatric patients to improve their oral health.

Use of Corporate Six Sigma Performance-Improvement Strategies to Reduce Incidence of Catheter-Related Bloodstream Infections in a Surgical ICU

BACKGROUND

Corporate performance-improvement methodologies can outperform traditional ones in addressing ICU-based adverse events. My colleagues and I used Six Sigma methodology to address our catheter-related bloodstream infection (CR-BSI) rate, which considerably exceeded the nationally established median over a 9-year period. We hypothesized that use of Six Sigma methodology would result in a substantial and sustainable decrease in our CR-BSI rate.

STUDY DESIGN

All patients were directly cared for by a geographically localized surgical ICU team in an academic tertiary referral center. CR-BSIs were identified by infection control staff using CDC definitions. Personnel trained in Six Sigma techniques facilitated performance-improvement efforts. Interventions included barrier precaution kits, new policies for catheter changes over guide wires, adoption of a new site-preparation antiseptic, direct attending supervision of catheter insertions, video training for housestaff, and increased frequency of dressing changes. After additional data analysis, chlorhexidine-silver catheters were used selectively in high-risk patients. The impact of interventions was assessed by monitoring the number of catheters placed between CR-BSIs.

RESULTS

Before the intervention period, 27 catheters were placed, on average, between individual CR-BSIs, a CR-BSI rate of 11 per 1,000 catheter days. After all operations were implemented, 175 catheters were placed between line infections, and average CR-BSI rate of 1.7/1,000 catheter days, a 650% improvement (p < 0.0001). Compared with historic controls, adoption of chlorhexidine-silver catheters in high-risk patients had a considerable impact (50% reduction; p < 0.05).

CONCLUSIONS

This represents the first successful application of Six Sigma corporate performance-improvement method impacting purely clinical outcomes. CR-BSI reduction was highly substantial and sustained after other traditional strategies had failed.

Catheter-Related Bloodstream Infections in the Intensive Care Unit Population

Catheter-related bloodstream infections (CRBIs) are a cause of significant morbidity and mortality in intensive care unit patients. Development of CRBIs may occur by several mechanisms. The role of fibrin and biofilm development and their impact on therapy are described. Multiple preventative strategies related to the insertion and maintenance of the catheter site have been identified. Topical antisepsis and use of antibiotic-impregnated catheters are also beneficial for reducing the incidence of CRBI. Antibiotic lock solutionsmay be effective in preventing CRBI for select patients with longterm catheter use. Treatment of CRBIs should be based on suspected organisms, whichmost commonly include staphylococci, gram-negatives, including Pseudomonas aeruginosa andCandida species. Duration of treatment and decisions regarding catheter removal are controversial. Evaluation and treatment of potential complications of CRBIs, including endocarditis, infected thrombophlebitis, osteomyelitis, and endophthalmitis, are essential.

In vitro new dialysis protocol to assay the antiseptic properties of a quaternary ammonium compound polymerized with denture acrylic resin

AIMS

To develop an in vitro protocol in order to assess the antiseptic properties of a quaternary ammonium compound polymerized with acrylic denture resin base, using experimental resin discs and dialysis membranes.

METHODS AND RESULTS

Experimental acrylic resin discs were polymerized with Poly 202063A, an ammonium compound (2-50%). Antiseptic properties were assayed against two reference strains (Escherichia coli, Staphylococcus aureus) and a laboratory strain (Candida albicans), using three different conditions (test A, B and C). In test A, according to classical protocols the resin discs were first soaked in large volumes of microbial inoculum (45 ml). An original dialysis protocol was then designed to recreate the small biofilm volume on the prosthetic surface. In test B, discs and bacterial inoculum (600 microl) were introduced in a dialysis bag and dialysed against a sterile buffer. A bactericidal effect was observed against E. coli and Staph. aureus (<0.1% viable cells in initial bacterial suspension). A dose-dependent fungistatic effect was observed against C. albicans. Finally, in test C discs and sterile buffer (600 microl) were introduced in a dialysis bag and dialysed against microbial inoculum. Reduced activity was found outside the dialysis bag, demonstrating that free ammonium was able to diffuse through the dialysis membrane, displaying antiseptic properties.

CONCLUSIONS

The present protocol demonstrated that a quaternary ammonium compound remains efficient after heat polymerization with an acrylic denture base resin, both in immediate and distant microbial environments.

SIGNIFICANCE AND IMPACT OF THE STUDY

Such removable prosthetic devices with intrinsic antiseptic properties would contribute to improve the long-term management of denture stomatitis.

Critical care infectious disease

Septic shock, toxic shock syndrome, acute respiratory distress syndrome, and catheter-related infections are conditions in which intensive care management of the patient may be necessary. Toxic shock syndrome is a toxin-mediated illness that is not limited to young menstruating women and should be considered in women and men who present with fever, hypotension, rash, and multiorgan dysfunction. Sepsis is the leading cause of death in critically ill patients in the United States and is the most common predisposing factor for acute lung injury or acute respiratory distress syndrome. Central venous catheters are often a necessity for optimal patient care in these critically ill patients.

Application of molecular typing methods to characterize nosocomial coagulase-negative staphylococci collected in a Greek hospital during a three-year period (1998-2000)

A total of 143 methicillin-resistant coagulase-negative staphylococci (MR-CNS) collected between 1998 and 2000 at the University Hospital of Patras, Greece, were characterized by antibiogram and genomic typing to define the clonal types endemic in this hospital and their evolution during the 3-year period. These isolates corresponded to 93 methicillin-resistant Staphylococcus epidermidis (MRSE) and 50 other MR-CNS, which were isolated from patients in different wards, exclusively from blood and catheter tips cultures. Pulsed-field gel electrophoresis (PFGE) of SmaI macrofragments and hybridization of ClaI digests with mecA and murE DNA probes were performed. The application of these methodologies demonstrated the existence, persistence and spread of MRSE, MR-Staphylococcus haemolyticus, and MR-Staphylococcus hominis clones in this hospital, whereas the SmaI/murE hybridization pattern was shown to be a valuable tool for the MRSE identification.

Early identification of bacteria leading to central venous catheter contamination

Catheter-related bloodstream infections (CRBSI) are a common problem in patients after central venous catheterization. Using DNA analysis we compared bacteria found on the tip of central venous catheters removed because of clinical signs of CRBSI with bacteria found on needle, dilator, and guidewire used for insertion of these catheters. In five of seven central venous catheters removed because of clinical signs of CRBSI, bacteria on the catheter tip were genetically identical to bacteria found on the insertion device, proving that catheter contamination in these cases was caused by contacting bacteria during the initial puncture. These findings may be important for antibiotic prophylaxis or therapy in patients at risk for CRBSI.

IMPLICATIONS

In five of seven central venous catheters removed because of clinical signs of catheter-related blood infections, DNA analysis showed bacteria found on the catheter tip to be identical with bacteria found on the puncture kits used for insertion of these catheters.