A European perspective on intravascular catheter-related infections: report on the microbiology workload, aetiology and antimicrobial susceptibility (ESGNI-005 Study)

Impact of an interventional bundle on complications associated with peripheral venous catheters in elderly patients

PURPOSE

Elderly patients admitted to geriatrics departments often require peripheral venous catheters (PVC), which should be inserted and maintained following a series of preventive recommendations. Our objective was to evaluate the impact of a training bundle comprising measures aimed at reducing complications associated with the use of PVC in elderly patients admitted to a tertiary teaching hospital.

METHODS

We performed a prospective study of patients who received a PVC within 24 h of admission to a geriatrics department. After a 10-month pre-interventional period, we implemented an educational and interventional bundle over a 9-month period. Follow-up was until catheter withdrawal. We analyzed and compared clinical and microbiological data between both study periods.

RESULTS

A total of 344 patients (475 PVC) were included (pre-intervention period, 204 patients (285 PVC); post-intervention period, 140 patients (190 PVC)). No statistically significant differences in demographic characteristics were observed between the study periods. The colonization and phlebitis rates per 1000 admissions in both periods were, respectively, 36.7 vs. 24.3 (p = 0.198) and 81.5 vs. 65.1 (p = 0.457). The main reason for catheter withdrawal was obstruction/malfunctioning (33.3%). Obstruction rate was higher for those inserted in the hand than for those inserted at other sites (55.7% vs. 44.3%, p = 0.045).

CONCLUSIONS

We found no statistically significant differences regarding phlebitis and catheter tip colonization rates. It is necessary to carry out randomized studies assessing the most cost-effective measure to reduce complications associated with PVC.

Incorporating anti-infective drugs into peripherally inserted catheters does not reduce infection rates in neonates

Purpose

This study assesses whether peripherally inserted central venous catheters (PICC), impregnated with anti-infective drugs, reduce the rate of infections in neonates compared with unimpregnated catheters.

Methods

A retrospective analysis was conducted on electronic patient records of neonates born between August 2014 and May 2020, who had PICCs inserted, either standard (S-PICC) or with anti-infective drugs (A-PICC). Catheter-related bloodstream infections (CRBSI) were diagnosed based on clinical symptoms, laboratory results, and mentioning of infection in the patient record. Data on dwell time, mechanical ventilation, insertion site, maximum C-reactive protein (CRP) concentration, and anti-infective drug use were analyzed.

Results

A total of 223 PICCs were included. The infection rates were A-PICC (18.9%) and S-PICC (12.5%), which were not significantly different (p = 0.257). A-PICCs had significantly longer dwell times than S-PICCs (median 372 vs. 219 h, p = 0.004). The time to infection was not different between the groups (p = 0.3). There were also no significant differences in maximum CRP, insertion site abnormalities, or anti-infective drug use between the groups.

Conclusion

This retrospective study did not find a significant reduction in infection rates by using PICCs containing anti-infective drugs in neonates. Current antibiotic impregnations do not seem to be effective in preventing blood stream infections.

[Are there benefits for catheter valves for catheter-associated quality of life? : Results of an investigation in 427 catheter wearers with life-long indication]

BACKGROUND

In urology, a subset of patients with lifelong urine drainage are fitted with a catheter valve. Data on catheter-related quality of life (crqol) in this subset of patients are missing.

AIM

Clarification of the whether there are advantages for valve-aided catheters in comparison with continuous urine drainage in catheter wearers with a lifelong indication.

METHODS

In all, 357 patients with a catheter with lifelong indication of continuous urine drainage from a previous study were compared with 70 valve-aided patients. The crqol was evaluated by a validated assessment with 25 items and five domains.

RESULTS

There were statistically more patients with a suprapubic catheter than with a transurethral indwelling catheter (73.4 vs. 54.4%, p = 0.005), significantly more patients with bladder voiding dysfunction (73.5 vs. 52.6%, p = 0.003) and significantly more patients with small catheter sizes (p = 0.001). Crqol was altogether slightly impaired with a median score of 4.2 (no impairment indicated by 5 points) in valve-aided patients, but crqol was more impaired in valve-aided patients compared to patients with continuous drainage (4.4 points, n. s.). Some items demonstrated more problems dealing with urinary urge in valve-aided patients, but catheter-related pain was more often worse in patients with continuous drainage.

CONCLUSION

There is no clear evidence for an advantage of a catheter valve over a continuous urine drainage system. Thus, the decision regarding a catheter-valve system must be made individually according to the indication and the preferences of the patient.

Analysis of risk factors of PICC-related bloodstream infection in newborns: implications for nursing care

Background

It is necessary to analyze the characteristics and risk factors of catheter-related bloodstream infection (CRBSI) in newborns with peripherally inserted central catheter (PICC).

Methods

Newborns undergoing PICC catheterization in the neonatal department of our hospital from January 1, 2020 to January 31, 2021 were included. The characteristics of newborns with and without CRBSI newborns were compared and analyzed. Logistic regression analyses were performed to evaluate the risk factors of CRBSI in newborns with PICC.

Results

Three hundred eighty-six newborns with PICC were included, of whom 41 newborns had the CRBSI, the incidence of CRBSI in newborns with PICC was 10.62%. There were significant differences regarding the birth weight, durations of PICC stay, 5-min Apgar score, site of PICC insertion of PICC between CRBSI and no CRBSI group (all P < 0.05), and there were no significant differences regarding the gender, gestational age, cesarean section, mechanical ventilation and length of hospital stay between CRBSI and no CRBSI group (all P > 0.05). Escherichia coli (26.08%) and Staphylococcus aureus (23.92%) were the most common CRBSI pathogens in newborns with PICC. Logistic regression analysis indicated that birth weight ≤ 1500 g (OR 1.923, 95% CI 1.135–2.629), durations of PICC stay ≥ 21 days (OR 2.077, 95% CI 1.024–3.431), 5-min Apgar score ≤ 7 (OR 2.198, 95% CI 1.135–3.414) and femoral vein insertion of PICC (OR 3.044, 95% CI 1.989–4.306) were the independent risk factors of CRBSI in neonates with PICC (all P < 0.05).

Conclusion

For newborns with low birth weight, longer durations of PICC stay and femoral vein PICC insertion, they may have higher risks of CRBSI, and medical staff should take targeted measures to reduce the development of CRBSI.

The challenge of COVID-19 for a Clinical Microbiology Department

OBJECTIVES

To quantify the workload and cost overload that the COVID-19 pandemic has meant for a Clinical Microbiology laboratory in a real-life scenario.

METHODS

We compared the number of samples received, their distribution, the human resources, and the budget of a Microbiology laboratory in the COVID pandemic (March-December 2020) with the same months of the previous year.

RESULTS

the total number of samples processed in the Clinical Microbiology laboratory in March to December 2020 increased 96.70% with respect to 2019 (from 246,060 to 483,993 samples), reflecting an increment of 127.50% when expressed as samples/1000 admissions (from 6057 to 13,780). The increase in workload was mainly at the expense of the virology (+2058%) and serology (+86%) areas. Despite additional personnel hiring, the samples processed per technician increased 12.5%. The extra cost attributed to Microbiology amounts to 6,616,511 euros (114.8%).

CONCLUSIONS

This is the first study to provide quantitative figures about workload and cost increase caused by the COVID-19 in a Microbiology laboratory.

Can vancomycin lock therapy extend the retention time of infected long-term catheters?

We assessed the success rate of vancomycin catheter lock therapy (VLT) in combination with systemic antimicrobials in patients with staphylococcal catheter-related bloodstream infection (C-RBSI). Over a 6-year period, we retrospectively collected clinical and microbiological data from patients with long-term central venous catheters and staphylococcal C-RBSI who were treated with systemic antimicrobials and VLT. We then assessed the success rate of VLT based on two criteria: 1) catheter retention time> 3 months and 2) catheter in place until end of use. We found 217 staphylococcal C-RBSI episodes, 115 (53.0%) of which were managed with conservative therapy. Of these, 76 (66.1%) were treated with VLT (85.5% coagulase-negative staphylococci and 14.5% Staphylococcus aureus). The success rate of VLT was 42.1% with criterion 1 and 71.1% with criterion 2. We did not find statistically significant differences between success and failure in the majority of the clinical data recorded. We only found differences for crude mortality in criterion 1 and for parenteral nutrition in criterion 2. The success of catheter retention using VLT was moderate, reaching slightly more than 70% when the catheter was kept in place until the end of use.

Structural and Functional Dynamics of Staphylococcus aureus Biofilms and Biofilm Matrix Proteins on Different Clinical Materials

Medical device-associated staphylococcal infections are a common and challenging problem. However, detailed knowledge of staphylococcal biofilm dynamics on clinically relevant surfaces is still limited. In the present study, biofilm formation of the Staphylococcus aureus ATCC 25923 strain was studied on clinically relevant materials-borosilicate glass, plexiglass, hydroxyapatite, titanium and polystyrene-at 18, 42 and 66 h. Materials with the highest surface roughness and porosity (hydroxyapatite and plexiglass) did not promote biofilm formation as efficiently as some other selected materials. Matrix-associated poly-N-acetyl-β-(1-6)-glucosamine (PNAG) was considered important in young (18 h) biofilms, whereas proteins appeared to play a more important role at later stages of biofilm development. A total of 460 proteins were identified from biofilm matrices formed on the indicated materials and time points-from which, 66 proteins were proposed to form the core surfaceome. At 18 h, the appearance of several r-proteins and glycolytic adhesive moonlighters, possibly via an autolysin (AtlA)-mediated release, was demonstrated in all materials, whereas classical surface adhesins, resistance- and virulence-associated proteins displayed greater variation in their abundances depending on the used material. Hydroxyapatite-associated biofilms were more susceptible to antibiotics than biofilms formed on titanium, but no clear correlation between the tolerance and biofilm age was observed. Thus, other factors, possibly the adhesive moonlighters, could have contributed to the observed chemotolerant phenotype. In addition, a protein-dependent matrix network was observed to be already well-established at the 18 h time point. To the best of our knowledge, this is among the first studies shedding light into matrix-associated surfaceomes of S. aureus biofilms grown on different clinically relevant materials and at different time points.

Clinical Features of Bloodstream Infections Associated with Peripheral Versus Central Venous Catheters

Introduction

This study aimed to compare the clinical characteristics and prognoses of central venous catheter-associated bloodstream infections (CVC-BSIs) with peripheral venous catheter-associated BSIs (PVC-BSIs).

Methods

This retrospective observational study was conducted between April 2011 and March 2013 at a teaching hospital in Tokyo, Japan. Adult patients who developed CVC-BSIs and PVC-BSIs more than 2 days after admission were included. Patients with both CVC-BSIs and PVC-BSIs were excluded. Clinical characteristics of patients with CVC-BSIs and PVC-BSIs were obtained from medical records, and 30-day all-cause mortality was measured as the clinical outcome.

Results

We enrolled 124 PVC-BSI cases and 110 CVC-BSI cases. Median age, age-adjusted Charlson score, Sequential Organ Failure Assessment score, sex, and ward type at BSI onset did not differ significantly between the two groups. The median duration of catheter indwelling was significantly shorter in the PVC-BSI group than in the CVC-BSI group. Staphylococcus aureus and Gram-negative bacilli infections were more frequent and coagulase-negative staphylococci (CNS) and Candida spp. infections were less frequent in the PVC-BSI group than in the CVC-BSI group. The prevalence of oxacillin resistance among causative S. aureus and CNS, 30-day all-cause mortality, and appropriateness of empirical and definitive antimicrobial therapies did not differ significantly between the two groups.

Conclusion

The pathogen species distribution varies between PVC-BSIs and CVC-BSIs. However, all-cause mortality does not differ between the two groups. PVCs are not safer than CVCs with respect to BSIs; therefore, it is necessary to use similar precautions relevant to CVC use in order to avoid unnecessary use of PVCs.

ACR Appropriateness Criteria® Radiologic Management of Central Venous Access

Obtaining central venous access is one of the most commonly performed procedures in hospital settings. Multiple devices such as peripherally inserted central venous catheters, tunneled central venous catheters (eg, Hohn catheter, Hickman catheter, C. R. Bard, Inc, Salt Lake City UT), and implantable ports are available for this purpose. The device selected for central venous access depends on the clinical indication, duration of the treatment, and associated comorbidities. It is important for health care providers to familiarize themselves with the types of central venous catheters available, including information about their indications, contraindications, and potential complications, especially the management of catheters in the setting of catheter-related bloodstream infections. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Polymicrobial bloodstream infections in the neonatal intensive care unit are associated with increased mortality: a case-control study

Background

Polymicrobial infections in adults and children are associated with increase in mortality, duration of intensive care and healthcare costs. Very few studies have characterized polymicrobial bloodstream infections in the neonatal unit. Considerable variation has been reported in incidence of polymicrobial infections and associated clinical outcomes. We characterized the risk factors and outcomes of polymicrobial bloodstream infections in our neonatal units in a tertiary hospital in North America.

Methods

In a retrospective case control study design, we identified infants in the neonatal intensive care unit with positive blood cultures at Texas Children’s Hospital, over a 16-year period from January 1, 1997 to December 31, 2012. Clinical data from online databases were available from January 2009 to December 2012. For each polymicrobial bloodstream infection (case), we matched three infants with monomicrobial bloodstream infection (control) by gestational age and birth weight.

Results

We identified 2007 episodes of bloodstream infections during the 16 year study period and 280 (14%) of these were polymicrobial. Coagulase-negative Staphylococcus, Enterococcus, Klebsiella and Candida were the most common microbial genera isolated from polymicrobial infections. Polymicrobial bloodstream infections were associated with more than 3-fold increase in mortality and an increase in duration of infection. Surgical intervention was a significant risk factor for polymicrobial infection.

Conclusion

The frequency and increased mortality emphasizes the clinical significance of polymicrobial bloodstream infections in the neonatal intensive care unit. Clinical awareness and focused research on neonatal polymicrobial infections is urgently needed.

Microbiocidal effects of various taurolidine containing catheter lock solutions

BACKGROUND & AIMS

We have recently shown that a catheter lock solution containing taurolidine dramatically decreases catheter-related bloodstream infections (CRBSI) in patients on home parenteral nutrition (HPN) when compared to heparin. Since several taurolidine formulations are commercially available, some of which also contain citrate or heparin, we were interested in the effect of these different locks on growth and biofilm formation of fungal, Gram-negative and Gram-positive pathogens that are known to impede HPN treatment.

METHODS

Clinical isolates obtained during CRBSI of HPN patients were grown in the presence of catheter locks (2% taurolidine, 1.34% taurolidine-citrate, 1.34% taurolidine-citrate-heparin, citrate and heparin) or phosphate buffered saline diluted in lysogeny broth medium for bacteria and sabouraud liquid medium for yeasts. Biofilm formation, assessed by crystal violet staining, and growth of clinical isolates were determined by optical density measurements.

RESULTS

We found that 12.5× diluted solutions of all taurolidine containing formulations completely prevented growth of Escherichia coli, Staphylococcus aureus and Candida glabrata. Growth of these microbes was detected earlier in 1.34% taurolidine-citrate(-heparin) than in 2% taurolidine, while citrate and heparin did not inhibit growth of clinical isolates compared to PBS. No differences in biofilm formation were found between taurolidine containing solutions.

CONCLUSION

Taurolidine containing lock solutions prevent growth of fungal, Gram-negative and Gram-positive pathogens. While 2% taurolidine appears to be the most potent in this respect in this in vitro setting, the relevance of the small differences in growth inhibition between the commercially available taurolidine containing lock solutions for clinical practice remains to be established.

Ethanol lock therapy (E-Lock) in the prevention of catheter-related bloodstream infections (CR-BSI) after major heart surgery (MHS): a randomized clinical trial

BACKGROUND

Lock-therapy with antimicrobials has been used for the treatment and prevention of catheter-related bloodstream infections (CR-BSI). Experiences with Ethanol-Locks (E-locks) have included therapeutic interventions with variable results. Patients undergoing Major Heart Surgery (MHS) are a high-risk population for CR-BSI.The aim of this study was to assess the efficacy and tolerance to E-Locks in the prevention of CR-BSI of patients undergoing MHS.

METHODS AND FINDINGS

This is an academic, prospective, randomized, non-blinded and controlled clinical trial assessing the incidence of CR-BSI of patients with E-locks (E-lock) and the tolerance to the procedure in comparison with patients receiving conventional catheter-care (CCC). Patients undergoing MHS with intravascular catheters for more than 48 hours were randomly assigned into treatment or control group by a computer-generated list of randomly assigned numbers. In the treatment group, all their catheter lumens were locked with an ethanol solution at 70% for two hours, every three days (E-Locks). The control group received conventional catheter-care (CCC). Overall, 200 patients with 323 catheters were included in the study, which was stopped after 10 months due to adverse events. Of them, 179 catheters (113 patients) had E-Locks and 144 catheters (87 patients) were CCC. Euroscore Surgical Risk in both groups was 4.04 vs 4.07 p = 0.94 respectively. The results for the E-Locks and CCC were as follows: Incidence of CR-BSI/1000 days of exposure 2.1 vs 5.2 (p = 0.33), catheter tip colonization 14 (7.8%) vs 6 (4.2%) patients (p = 0.17), median length of hospital stay, 15 vs 16 days (p = 0.77). Seven patients (6.19%), all in the ethanol branch, had to discontinue the trial due to intolerance or adverse events.

CONCLUSIONS

We do not recommend prophylaxis of CR-BSI with ethanol-lock on a routine basis in patients undergoing Major Heart Surgery.

TRIAL REGISTRATION

Clinical Trials.gov NCT01229592.

[Virulence factors and pathophysiology of extraintestinal pathogenic Escherichia coli]

Extraintestinal pathogenic Escherichia coli (ExPEC) causing urinary tract infections, bacteraemia or meningitis are characterized by a particular genetic background (phylogenetic group B2 and D) and the presence, within genetic pathogenicity islands (PAI) or plasmids, of genes encoding virulence factors involved in adhesion to epithelia, crossing of the body barriers (digestive, kidney, bloodbrain), iron uptake and resistance to the immune system. Among the many virulence factors described, two are particularly linked with a pathophysiological process: type P pili PapGII adhesin is linked with acute pyelonephritis, in the absence of abnormal flow of urine, and the K1 capsule is linked with neonatal meningitis. However, if the adhesin PapGII appears as the key factor of pyelonephritis, such that its absence in strain causing the infection is predictive of malformation or a vesico-ureteral reflux, the meningeal virulence of E. coli can not be reduced to a single virulence factor, but results from a combination of factors unique to each clone, and an imbalance between the immune defenses of the host and bacterial virulence.

Catheter related bloodstream infection (CR-BSI) in ICU patients: making the decision to remove or not to remove the central venous catheter

Background

Approximately 150 million central venous catheters (CVC) are used each year in the United States. Catheter-related bloodstream infections (CR-BSI) are one of the most important complications of the central venous catheters (CVCs). Our objective was to compare the in-hospital mortality when the catheter is removed or not removed in patients with CR-BSI.

Methods

We reviewed all episodes of CR-BSI that occurred in our intensive care unit (ICU) from January 2000 to December 2008. The standard method was defined as a patient with a CVC and at least one positive blood culture obtained from a peripheral vein and a positive semi quantitative (>15 CFU) culture of a catheter segment from where the same organism was isolated. The conservative method was defined as a patient with a CVC and at least one positive blood culture obtained from a peripheral vein and one of the following: (1) differential time period of CVC culture versus peripheral culture positivity of more than 2 hours, or (2) simultaneous quantitative blood culture with 5∶1 ratio (CVC versus peripheral).

Results

53 CR-BSI (37 diagnosed by the standard method and 16 by the conservative method) were diagnosed during the study period. There was a no statistically significant difference in the in-hospital mortality for the standard versus the conservative method (57% vs. 75%, p = 0.208) in ICU patients.

Conclusion

In our study there was a no statistically significant difference between the standard and conservative methods in-hospital mortality.

Prospective, randomised study of selective versus routine culture of vascular catheter tips: patient outcome, antibiotic use and laboratory workload

In order to assess the value of vascular catheter tip culture in patients with negative blood cultures, all tip samples from hospitalised patients were prospectively randomised (1:1) to two different routines for processing catheters: culture of all tips (routine A) vs culture only of tips from patients with concomitant bacteraemia or fungaemia (routine B). Over a nine-month period, 426 catheters from 318 patients were randomly assigned to routine A and 429 catheters from 322 patients to routine B (n=40 [corrected] patients). We compared the outcome and costs from both groups. No statistically significant differences were found with respect to demographic data, mortality, hospital stay or antimicrobial use. In non-bacteraemic/fungaemic cases (N=517), days on antimicrobial therapy after catheter withdrawal were significantly higher in patients from group A [10.0 days (interquartile range, IQR): 6.0-14.0] vs 8.0 days (IQR: 4.7-12.2), P=0.03], as was the number of daily defined doses (DDDs) of antimicrobials [10.8 DDDs (IQR: 2.4-26.9) vs 7.5 DDDs (IQR: 1.5-20.0), P=0.03]. Median antimicrobial cost per treated patient was significantly higher in group A: €222.30 (IQR: €20.30-€1,030.60) vs €109.10 (IQR: €10.90-€653.20), P=0.05. If all vascular catheter tips were processed according to routine B, the microbiology laboratory workload would decrease by 77% for the total number of catheters processed. Microbiology laboratories should not routinely culture catheter tips in patients without bacteraemia or fungaemia.

Catheter-related bloodstream infections: catheter management according to pathogen

Central-line access is an essential part of modern healthcare practice; however, catheter-related bloodstream infection is a major problem that causes substantial morbidity and mortality, and excess length of stay and cost. The risk of infection depends on the type of device, the site of insertion, the underlying conditions and the appropriate prevention measures taken during catheter insertion. Management of catheter-related bloodstream infection involves deciding on catheter removal, antimicrobial catheter lock solution and the type and duration of systemic antimicrobial therapy. Systemic antimicrobial use is essential but, although generally effective in controlling sepsis, it often fails to sterilise the line, increasing the incidence of complications or recurrence. The decision regarding whether the catheter should be removed or retained is therefore crucial. One of the major factors to be considered is the type of organism involved in the catheter-related infection. This review outlines the epidemiology, pathogenesis, diagnosis, microbiology and management of catheter-related infections, mainly focusing on the management of the intravascular device according to the pathogen.

ICU stay promotes enrichment and dissemination of multiresistant coagulase-negative staphylococcal strains

Patients in the intensive care unit (ICU) are prone to be colonized and infected by multi-resistant bacteria. It is previously known that nosocomial infections are often preceded by cross-transmission events. The aim of the present investigation was to study the impact of the patient's length of ICU stay on the resistance patterns, diversity and dissemination of coagulase-negative staphylococci (CoNS) within and between patients. Two groups of patients were studied, including 20 consecutive patients sampled within 2 h from admission (short-stayers, SS), and all patients treated for at least 5 d in the ICU (long-stayers, LS), available for sampling every second week (n = 15). Sampling was performed from 5 sites: oropharynx, nares, neck, axilla and perineum. A total of 868 CoNS isolates deriving from LS patients and 403 isolates from SS patients were analysed for antimicrobial susceptibility, clonal diversity and dissemination within and between patients. The highest resistance rates were seen for oxacillin and ciprofloxacin, being 92% and 83%, respectively. Long-stayers were at significantly higher risk of being colonized with CoNS isolates resistant against oxacillin, clindamycin, ciprofloxacin, gentamicin as well as with multiresistant strains. By genotyping 22 phenotypes that were shared among at least 2 patients, 32 PFGE types of which 16 colonized more than 1 individual were identified. One of the clones was isolated from 10 individuals, including 2 SS patients, indicating an epidemic strain. Prolonged ICU stay was significantly correlated to decreased clonal diversity, increased endogenous dissemination of resistant strains and cross-transmission. The results emphasize the importance of good infection control practice, especially in this vulnerable group of patients.

Evaluation of colonisation of peripheral venous catheters inserted by prehospital emergency service teams (SMUR) in France

There are no data in the literature on colonisation of peripheral venous catheters (PVCs) inserted by French prehospital emergency and resuscitation service teams (SMUR). In a descriptive and prospective study we evaluated colonisation of PVCs inserted and managed solely by a SMUR team. A total of 171 PVCs were analysed. Bacteriological results were positive for seven catheters (4.09%/threshold=10(2)cfu/mL). Our analyses of the characteristics of patients and interventions show a significantly higher number of elderly patients among those colonised (P=0.02) with less satisfactory venous access (P=0.006) and smaller catheter bores (P=0.009). No differences were seen regarding the other evaluation criteria: gender, aetiology, site of intervention, number and site of venepuncture procedures, blood pressure and duration of catheterisation. The absolute value of colonisation seen in our study appears consistent with those reported in the literature, but no comparisons are possible due to widely divergent catheterisation times between published work (days) and our own data (minutes). Our results suggest a reassessment of current recommendations of routine changeover of these catheters, with the attendant discomfort for patients and cost in terms of time and money. We recommend a randomised study comparing catheter colonisation levels associated with routine catheter replacement with targeted replacement based on risk factors.

Molecular detection of aggregation substance, enterococcal surface protein, and cytolysin genes and in vitro adhesion to urinary catheters of Enterococcus faecalis and E. faecium of clinical origin

It has been hypothesized that nosocomial enterococci might have virulence factors that enhance their ability to colonise hospitalised patients. The objectives of this study were to investigate the prevalence of genes encoding 3 virulence factors: aggregation substance (asa1), enterococcal surface protein (esp), and 5 genes within the cytolysin operon (cylA, cylB, cylM, cylL(L), cylL(S)) and cytolysin production in 115 enterococcal clinical isolates (21 Enterococcus faecium and 94 E. faecalis). Adhesion to siliconized latex urinary catheters in relation to presence of esp was analysed in a subset of isolates. The isolates were previously characterised by pulsed-field gel electrophoresis (PFGE). esp was the only virulence gene found in E. faecium. It was found in 71% of the 21 E. faecium isolates. asa1, esp, and the cyl operon were found in 79%, 73% and 13% respectively, of the 94 E. faecalis isolates. There was a complete agreement between presence of the cyl operon and phenotypic cytolysin production. Isolates belonging to a cluster of genetically related isolates carried esp and asa1 more often when compared to unique isolates. No difference was found with respect to cyl genes. E. faecalis isolates adhered with higher bacterial densities than E. faecium. E. faecalis isolates within the same PFGE cluster adhered with similar bacterial densities, but there was no association between adhesion and the presence of esp when isolates within the same cluster were compared. In conclusion, E. faecalis isolates with high-level gentamicin resistance (HLGR) belonging to clusters of genetically related isolates widely distributed in Swedish hospitals, were likely to carry both esp and asa1. Adhesion was not affected by esp.

Use of cultivation-dependent and -independent techniques to assess contamination of central venous catheters: a pilot study

Background

Catheters are the most common cause of nosocomial infections and are associated with increased risk of mortality, length of hospital stay and cost. Prevention of infections and fast and correct diagnosis is highly important.

Methods

In this study traditional semiquantitative culture-dependent methods for diagnosis of bacteria involved in central venous catheter-related infections as described by Maki were compared with the following culture-independent molecular biological methods: Clone libraries, denaturant gradient gel electrophoresis, phylogeny and fluorescence in situ hybridization.

Results

In accordance with previous studies, the cultivation of central venous catheters from 18 patients revealed that S. epidermidis and other coagulase-negative staphylococci were most abundant and that a few other microorganisms such as P. aeruginosa and K. pneumoniae occasionally were found on the catheters. The molecular analysis using clone libraries and sequencing, denaturant gradient gel electrophoresis and sequencing provided several important results. The species found by cultivation were confirmed by molecular methods. However, many other bacteria belonging to the phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes were also found, stressing that only a minor portion of the species present were found by cultivation. Some of these bacteria are known to be pathogens, some have not before been described in relation to human health, and some were not closely related to known pathogens and may represent new pathogenic species. Furthermore, there was a clear difference between the bacterial species found in biofilm on the external (exluminal) and internal (luminal) side of the central venous catheter, which can not be detected by Maki's method. Polymicrobial biofilms were observed on most of the catheters and were much more common than the cultivation-dependent methods indicated.

Conclusion

The results show that diagnosis based on molecular methods improves the detection of microorganisms involved in central catheter-related infections. The importance of these microorganisms needs to be investigated further, also in relation to contamination risk from improper catheter handling, as only in vivo contaminants are of interest. This information can be used for development of fast and more reliable diagnostic tools, which can be used in combination with traditional methods.

Comparison between qualitative and semiquantitative catheter-tip cultures: laboratory diagnosis of catheter-related infection in newborns

This prospective study evaluated semiquantitative and qualitative catheter-culture methods for diagnosis of catheter-related infection (CRI) in newborns. Catheter tips from newborns admitted to the Neonatal Unit of the University Hospital of the Botucatu Medical School, UNESP were included in the study. Catheter cultures were performed with both semiquantitative and qualitative techniques. For CRI diagnosis, microorganisms isolated from catheter cultures and from peripheral blood cultures were identified and submitted to agent susceptibility test. The gold standard was the certain CRI diagnosis when same microorganism (specie and profile of susceptibility to agents) was isolated from both catheter tips and peripheral blood culture. A total of 85 catheters from 63 newborns were included in the study. The semiquantitative culture method, despite presenting lower sensitivity (90%), showed higher specificity (71%) when compared to 100% of sensitivity and 60% of specificity in the qualitative method. The identification of the microorganisms obtained from the catheter cultures showed a prevalence of coagulase-negative staphylococci (CNS) species. The specie Staphylococcus epidermidis (77.5%) was the prevalent in the catheters with positive semiquantitative cultures. Among 11 episodes with CRI diagnosis, 8 (72.7%) were associated with CNS species, of which 6 were S. epidermidis. Two episodes of CRI by S. aureus and one by Candida parapsilosis were also detected. The semiquantitative catheter-culture method showed advantages for CRI diagnosis in newborns when compared to the conservative qualitative method.

In vitro activity of omiganan pentahydrochloride tested against vancomycin-tolerant, -intermediate, and -resistant Staphylococcus aureus

Omiganan, a novel topical cationic peptide active against a broad spectrum of bacteria and yeast, is targeted for the prevention of catheter-associated infections. The spectrum of this agent was evaluated against contemporary methicillin-(oxacillin)-resistant Staphylococcus aureus (MRSA; 109 isolates), including subgroups displaying reduced susceptibility to vancomycin. Strain phenotypes included: vancomycin-tolerant (MBC/MIC ratio, > or = 32-fold);vancomycin-intermediate (VISA; MIC values, 4-8 microg/ml); heterogeneous vancomycin-intermediate (hVISA); and vancomycin-resistant (VRSA; MIC values, > or = 16 microg/ml) S. aureus. All S. aureus tested were inhibited by < or = 64 microg/ml of omiganan, with MIC(50)/MIC(90) values of 16/32 microg/ml, respectively. Compared to wild-type S. aureus, MIC(90) values were only 2-fold greater for vancomycin-tolerant, hVISA and VISA strains. The VRSA isolates, representing the most resistant strains tested, were inhibited by 16 microg/ml (mode for all groups). Omiganan demonstrated potent activity against S. aureus, regardless of harbored resistance mechanism. Given the worrisome emergence of S. aureus with reduced susceptibility to vancomycin, the demonstration that omiganan remains equally active against all isolates of this species at a level significantly below the clinical formulation concentration (1% gel; 10,000 microg/ml) is an important attribute.

Methicillin resistance in Staphylococcus aureus and coagulase-negative staphylococci: epidemiological and molecular aspects

Infections caused by the genus Staphylococcus are of great importance for human health. Staphylococcus species are divided into coagulase-positive staphylococci, represented by S. aureus, a pathogen that can cause infections of the skin and other organs in immunocompetent patients, and coagulase-negative staphylococci (CNS) which comprise different species normally involved in infectious processes in immunocompromised patients or patients using catheters. Oxacillin has been one of the main drugs used for the treatment of staphylococcal infections; however, a large number of S. aureus and CNS isolates of nosocomial origin are resistant to this drug. Methicillin resistance is encoded by the mecA gene which is inserted in the SCC mec cassette. This cassette is a mobile genetic element consisting of five different types and several subtypes. Oxacillin-resistant strains are detected by phenotypic and genotypic methods. Epidemiologically, methicillin-resistant S. aureus strains can be divided into five large pandemic clones, called Brazilian, Hungarian, Iberian, New York/Japan and Pediatric. The objective of the present review was to discuss aspects of resistance, epidemiology, genetics and detection of oxacillin resistance in Staphylococcus spp., since these microorganisms are increasingly more frequent in Brazil.

Antimicrobial activity of omiganan pentahydrochloride against contemporary fungal pathogens responsible for catheter-associated infections

Omiganan, a bactericidal and fungicidal cationic peptide being developed as a topical gel for prevention of catheter-associated infections, inhibited commonly occurring fungal pathogens including Candida spp. (106 isolates) at <or=256 microg/ml and molds (including 10 Aspergillus isolates) at <or=1,024 microg/ml. All fungi were inhibited by omiganan at concentrations well below the 1% (10,000 microg/ml) clinical formulation, including species with reduced susceptibility to azoles and echinocandins.

Microorganisms responsible for intravascular catheter-related bloodstream infection according to the catheter site

OBJECTIVE

Current guidelines for the management of intravascular catheter-related bloodstream infection (IVC-RBSI) recommend that empirical antimicrobial therapy must have activity against Gram-positive bacteria, but additional empirical coverage for Gram-negative bacteria may be needed for severely ill or immunocompromised patients, and antifungal therapy may be needed in some situations. We hypothesized that the spectrum of etiological microorganisms responsible for IVC-RBSI and, in relation to that, the choice of empirical antimicrobial therapy depends on the catheter insertion site. We therefore compared the proportion of IVC-RBSI due to Gram-negative bacteria and yeasts according to catheter site.

DESIGN

Prospective cohort study from May 1, 2000, to April 30, 2004.

SETTING

A 24-bed medical-surgical intensive care unit in a 650-bed tertiary hospital.

PATIENTS

Patients requiring a central venous or arterial catheter.

MEASUREMENTS AND MAIN RESULTS

We diagnosed 88 IVC-RBSIs, comprising 36 femoral catheter sites (26 femoral venous and ten femoral arterial sites) and 52 other catheter sites (36 jugular venous, 11 subclavian venous, and five radial arterial sites). No differences were found between IVC-RBSI of femoral vs. other catheter sites for age, sex, Acute Physiology and Chronic Health Evaluation II, diagnosis at admission, use of antimicrobials, the time the catheter responsible for IVC-RBSI had been in place, or the duration of intensive care unit stay before IVC-RBSI. The proportion of IVC-RBSIs due to Gram-negative bacteria was higher in femoral, 14 of 36 (38.89%), than in the other catheter sites, 4 of 52 (7.69%) (odds ratio, 7.48; 95% confidence interval, 2.19-25.54; p = .001). Also, the proportion of IVC-RBSIs due to yeasts was higher in femoral, 6 of 36 (16.67%), than in the other catheter sites, 1 of 52 (1.92%) (odds ratio, 10.20; 95% confidence interval, 1.17-88.85; p = .035).

CONCLUSIONS

Empirical antifungal therapy would seem to be indicated in patients with suspected femoral catheter-related bloodstream infection.

A randomized and prospective study of 3 procedures for the diagnosis of catheter-related bloodstream infection without catheter withdrawal

BACKGROUND

Suspicion of catheter-related bloodstream infection (CR-BSI) leads frequently to unnecessary catheter withdrawals, and many catheter-tip cultures yield negative results. The objective of this study was to compare the yield of 3 microbiological procedures to assess CR-BSI without catheter withdrawal.

METHODS

The study was prospectively performed in a group of patients without neutropenia or blood disorders who were admitted to the intensive care unit during a 37-month period with sepsis suspected on clinical grounds and who had central venous catheters inserted for >48 h. The microbiological procedures compared were semiquantitative cultures from hub and skin (superficial), differential quantitative blood cultures, and differential time to positivity between cultures of blood obtained from catheter hubs and peripheral blood.

RESULTS

Of the 204 episodes of suspected CR-BSI included in the study, 28 were confirmed to be CR-BSI. We obtained the following results for sensitivity, specificity, positive and negative predictive values, and accuracy: superficial cultures, 78.6%, 92.0%, 61.1%, 96.4%, and 90.2%, respectively; differential quantitative blood cultures, 71.4%, 97.7%, 83.3%, 95.6%, and 94.1%, respectively; and differential time to positivity, 96.4%, 90.3%, 61.4%, 99.4%, and 91.2%, respectively.

CONCLUSIONS

CR-BSI can be assessed without catheter withdrawal in patients without neutropenia or blood disorders who have catheters inserted for a short time and are hospitalized in the intensive care unit. Convenience, use of resources, and expertise should determine the technique of choice in different medical contexts. Because of ease of performance, low cost, and wide availability, we recommend combining semiquantitative superficial cultures and peripheral vein blood cultures to screen for CR-BSI, leaving differential quantitative blood cultures as a confirmatory and more specific technique.

Comparison of phenotypic with genotypic procedures for confirmation of coagulase-negative Staphylococcus catheter-related bloodstream infections

We sought here to review the present definition of catheter-related bloodstream infections (CR-BSI) due to coagulase-negative staphylococci (CNS) by comparing the routine phenotypic methods with a genotypic procedure that considers different morphotypes. Our phenotypic characterization of CNS isolates included routine identification with biotype and antibiotype. The genotypic diagnosis was based on longer incubation periods with the consideration of all morphotypes and molecular typing by pulsed-field gel electrophoresis techniques. We prospectively selected 61 episodes of suspected CR-BSI by CNS occurring during 1 year, based on the presence of a compatible clinical setting and the isolation of one or more CNS from blood and catheter tip. Of these episodes, 47 (77%) were identified as true episodes of CR-BSI based on the presence of microorganisms of the same genotype in the blood and on the catheter tip. The sensitivity, specificity, positive predictive, negative predictive, accuracy, positive likelihood ratio, and negative likelihood ratio values obtained by different phenotypic microbiological approaches to establish the diagnosis of CR-BSI were as follows: identity at species level (78.7%, 85.7%, 94.9%, 54.5%, 80.3%, 5.51, and 0.25, respectively); identity of species and biotype (59.6%, 92.9%, 96.6%, 40.6%, 67.2%, 8.34, and 0.44, respectively); identity of species and antibiotype (61.7%, 92.9%, 96.7%, 41.9%, 68.8%, 8.64, and 0.41, respectively); and identity of species, biotype, and antibiotype (48.9%, 92.9%, 95.8%, 35.1%, 59%, 6.85, and 0.55, respectively). Our study demonstrates the inaccuracy of the diagnosis of CNS CR-BSI when the current definition based on conventional routine microbiological practice is followed. A new definition of CNS CR-BSI is necessary, at least as an epidemiological and research tool.

[Direct fluorescent and indirect immunofluorescent assay in buffy coat for candidemia diagnosis in pediatric patients: a comparative study]

The diagnosis of candidemia by blood culture has poor sensitivity; therefore, immunossupresed patients and those with risk factors may receive empirical antifungal therapy, wich is potentially toxic. Fluorescent tests have been developed to obtain an early and more sensitive diagnosis than blood culture. The aim of this study was to compare indirect immunofluorescence vs direct calcofluor white fluorescence in buffy coat for candidemia diagnosis. Sensitivity, specificity, predictive values, of positive and negative samples were 60%, 86%, 33%, 95% and 90%, 80%, 35%, 99%, for indirect immunofluorescence and calcofluor white, respectively.