Central Venous Catheter Tip Cultures Research Articles

Central Venous Catheter Related Bloodstream Infections in Medical Intensive Care Unit Patients in a Tertiary Referral Centre

To determine the incidence of central line associated bloodstream infections (CLABSIs) in the medical intensive care unit (ICU) and ward setting at All India Institute of Medical Sciences (AIIMS), New Delhi. The study was conducted in the medical ICU, a 9-bedded ICU at the AIIMS, a tertiary care teaching hospital. The study design was a prospective observational study. One hundred patients admitted to medical ICU and the ward at AIIMS with an indwelling, non-tunnelled central venous catheter (CVC) in place at admission and those with a hospital stay with indwelling CVC for more than 48 hours were monitored. These patients were followed daily for the development of new onset sepsis 48 hours after insertion of CVC, in which case three sets of blood samples for culture were drawn over a span of 24 hours. Incidence of CLABSIs was measured per 1000 central line days. One hundred patients hospitalised for an aggregate 1119 days acquired 29 hospital-acquired infections (HAIs), a rate of 38.8% or 31.2 HAIs per 1000 hospital days. The incidence of bloodstream infections (BSIs) in this group was 6.8%. No case of laboratory confirmed CLABSIs could be demonstrated. Incidence of clinical sepsis was 27.6% or 8.2 per 1000 CVC days. There were 9 cases out of the 29 patients (39.7%) who had evidence of HAIs with no apparent focus of infection. Only one of these cases had evidence of BSI with isolation of Staphylococcus aureus in both CVC tip culture and the simultaneous blood culture; however the antibiograms were different. The low rate of BSIs in the present study and the absence of occurrence of a laboratory confirmed CLABSI should be interpreted in the light of the small sample size of the study and the multitude of antibiotics received before the development of HAI.

Atomic force microscopy and scanning electron microscopy as alternative methods of early identification of pathogens causing catheter-related bloodstream infections of patients in ICU

Abstract Introduction Vascular catheters are an indispensable element of the therapy of patients in intensive care. Their use is associated with the possibility of complications, including infectious. According to various sources, the incidence of catheter-related bloodstream infections (CRBSIs) ranges from 0.1 to 22.7 per 1,000 catheter days. Materials and Methods The central venous catheter tip culture samples were collected from 24 patients with suspected catheter-related bloodstream infection, from three intensive care units (ICUs). The results of microscopic examinations: atomic force microscope (AFM) and scanning electron microscope (SEM) were compared with the results of microbiological analysis of the central venous catheter tip and blood collected from the catheter. Results The microscopic examination and microbiological analysis of both the blood and central venous catheter samples confirmed the presence of microorganisms in 16 cases (double positive result). Our study was conducted in a short period of time (up to 6 hours) and it gave an initial answer to the question about the type of microorganisms colonising the central venous catheter. In one patient the infection was not caused by removal of the central venous catheter. However, not all results were fully consistent within the two diagnostic methods. The colonisation of the central venous catheter with Pseudomonas aeruginosa and Staphylococcus epidermidis was microbiologically confirmed, but it was not confirmed by the microscopic examination of the sample collected from patient No. 20. However, the examination enabled preliminary assessment of the microorganism colonising the catheter, which may have caused the blood infection. It cannot be ruled out that Pseudomonas aeruginosa bacilli were grown on the catheter that came into contact with blood from another source of infection, e.g. the respiratory, nervous or urinary systems. Information on the presence of cocci-shaped bacteria forming characteristic clusters or rods may enable initial diagnosis of catheter-related bloodstream infection if it is accompanied by typical clinical symptoms. Alternative diagnostics also provides valuable information on the presence of biofilm, which is a factor hindering the body’s response to infection and penetration of antibiotics. Conclusions Our pilot study presents new diagnostic possibilities of microscopic imaging with the atomic force microscope (AFM) and scanning electron microscope (SEM) to identify pathogens on routinely used disposable medical devices, such as the central venous catheter. On the other hand, this range of diagnostics reveals the potential to constantly improve medical materials which come into direct contact with patients’ tissues. It is important to create a database of microscopic images, which would be a repeatable diagnostic pattern and fully correlated with the results of microbiological analysis, because it would facilitate initial quick diagnosis of a potential CRBSI.

Antimicrobial-impregnated central venous catheters for preventing neonatal bloodstream infection: the PREVAIL RCT.

Clinical trials show that antimicrobial-impregnated central venous catheters reduce catheter-related bloodstream infection in adults and children receiving intensive care, but there is insufficient evidence for use in newborn babies. The objectives were (1) to determine clinical effectiveness by conducting a randomised controlled trial comparing antimicrobial-impregnated peripherally inserted central venous catheters with standard peripherally inserted central venous catheters for reducing bloodstream or cerebrospinal fluid infections (referred to as bloodstream infections); (2) to conduct an economic evaluation of the costs, cost-effectiveness and value of conducting additional research; and (3) to conduct a generalisability analysis of trial findings to neonatal care in the NHS. Three separate studies were undertaken, each addressing one of the three objectives. (1) This was a multicentre, open-label, pragmatic randomised controlled trial; (2) an analysis was undertaken of hospital care costs, lifetime cost-effectiveness and value of information from an NHS perspective; and (3) this was a retrospective cohort study of bloodstream infection rates in neonatal units in England. The randomised controlled trial was conducted in 18 neonatal intensive care units in England. Participants were babies who required a peripherally inserted central venous catheter (of 1 French gauge in size). The interventions were an antimicrobial-impregnated peripherally inserted central venous catheter (coated with rifampicin-miconazole) or a standard peripherally inserted central venous catheter, allocated randomly (1 : 1) using web randomisation. Study 1 - time to first bloodstream infection, sampled between 24 hours after randomisation and 48 hours after peripherally inserted central venous catheter removal. Study 2 - cost-effectiveness of the antimicrobial-impregnated peripherally inserted central venous catheter compared with the standard peripherally inserted central venous catheters. Study 3 - risk-adjusted bloodstream rates in the trial compared with those in neonatal units in England. For study 3, the data used were as follows: (1) case report forms and linked death registrations; (2) case report forms and linked death registrations linked to administrative health records with 6-month follow-up; and (3) neonatal health records linked to infection surveillance data. Study 1, clinical effectiveness - 861 babies were randomised (antimicrobial-impregnated peripherally inserted central venous catheter, n = 430; standard peripherally inserted central venous catheter, n = 431). Bloodstream infections occurred in 46 babies (10.7%) randomised to antimicrobial-impregnated peripherally inserted central venous catheters and in 44 (10.2%) babies randomised to standard peripherally inserted central venous catheters. No difference in time to bloodstream infection was detected (hazard ratio 1.11, 95% confidence interval 0.73 to 1.67; p = 0.63). Secondary outcomes of rifampicin resistance in positive blood/cerebrospinal fluid cultures, mortality, clinical outcomes at neonatal unit discharge and time to peripherally inserted central venous catheter removal were similar in both groups. Rifampicin resistance in positive peripherally inserted central venous catheter tip cultures was higher in the antimicrobial-impregnated peripherally inserted central venous catheter group (relative risk 3.51, 95% confidence interval 1.16 to 10.57; p = 0.02) than in the standard peripherally inserted central venous catheter group. Adverse events were similar in both groups. Study 2, economic evaluation - the mean cost of babies' hospital care was £83,473. Antimicrobial-impregnated peripherally inserted central venous catheters were not cost-effective. Given the increased price, compared with standard peripherally inserted central venous catheters, the minimum reduction in risk of bloodstream infection for antimicrobial-impregnated peripherally inserted central venous catheters to be cost-effective was 3% and 15% for babies born at 23-27 and 28-32 weeks' gestation, respectively. Study 3, generalisability analysis - risk-adjusted bloodstream infection rates per 1000 peripherally inserted central venous catheter days were similar among babies in the trial and in all neonatal units. Of all bloodstream infections in babies receiving intensive or high-dependency care in neonatal units, 46% occurred during peripherally inserted central venous catheter days. The trial was open label as antimicrobial-impregnated and standard peripherally inserted central venous catheters are different colours. There was insufficient power to determine differences in rifampicin resistance. No evidence of benefit or harm was found of peripherally inserted central venous catheters impregnated with rifampicin-miconazole during neonatal care. Interventions with small effects on bloodstream infections could be cost-effective over a child's life course. Findings were generalisable to neonatal units in England. Future research should focus on other types of antimicrobial impregnation of peripherally inserted central venous catheters and alternative approaches for preventing bloodstream infections in neonatal care. Current Controlled Trials ISRCTN81931394. This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 57. See the NIHR Journals Library website for further project information.

Frequency and antimicrobial susceptibility pattern of isolates in central venous catheter colonization.

Colonization of central venous catheters increases the risk of blood stream infections and is associated with increased morbidity, mortality and excess hospital costs. Objectives: To estimate frequency of central venous catheter colonization. Study Design: Cross Sectional study. Setting: Microbiology Laboratory of Punjab Institute of Cardiology, Lahore. Period: May 2018 to December 2018. Material and Methods: Total 116 specimens of central venous catheters were received in the laboratory and processed to isolate various organisms. Organisms were identified on the basis of colonial morphology, Gram staining and biochemical tests. Antimicrobial sensitivity testing was performed and results were recorded. Results: Out of total 116 specimens of central venous catheters, bacterial growth was obtained from 74.1% of central venous catheter tips. From 86 cultures yielding growth, 94 micro-organisms were isolated. The most frequent organisms isolated from central venous catheter tip culture in decreasing order of frequency were Coagulase negative staphylococci (29.8%), S. aureus (24.5%), Candida species (23.4%), Klebsiella species (12.8%), and Acinetobacter spp. (4.3%). Drug susceptibility pattern of isolates was recorded. Conclusion: Central venous catheters can get colonized and lead to catheter related infections. Implementation of prevention programs can result in decrease in colonization rate of catheters and thus Catheter related infections.

Dwindling Utilization of Central Venous Catheter Tip Cultures: An Analysis of Sampling Trends and Clinical Utility at 128 US Hospitals, 2009-2014.

At 128 US hospitals, from 2009-2014, a 17% decline occurred annually in central venous catheter tips sent for culture: a 6-fold decrease from blood culture sampling trends. The positive predictive value was low (23%). Tip culture use often does not conform to recommendations and offers limited independent treatment opportunities.

2089. Dwindling Utilization of Central Venous Catheter Tip Cultures: An Analysis of Sampling Trends and Clinical Utility at 128 U.S. Hospitals 2009–2014

BackgroundThe 2009 Infectious Diseases Society of America management guidelines for catheter-related bloodstream infection (CR-BSI) recommend the use of central venous catheter (CVC) tip cultures (TC) to aid in diagnosing CR-BSI. However, reimbursement penalties for CR-BSI and emerging evidence supporting watchful waiting rather than removing CVCs may have impacted sampling tendencies, and as such, the uptake of this recommendation and its clinical utility remain unknown.MethodsInpatient encounters with ≥1 orders for CVC TC and blood culture (BC; irrespective of collection site) respectively were identified in the Cerner Health Facts electronic health record database. Five-year trends (2009–2014) in TC sampling per 10,000 patients were analyzed and annual percent change (APC) in TC vs. BC sampling were compared. The proportions of (a) TCs with growth of noncontaminant microbial taxa and (b) taxon concordant TC–BC pairs sampled within 2 days of each other were calculated.ResultsBetween 2009 and 2014, 18,080 TCs were sampled during 16,092 encounters among 14,844 patients at 128 US hospitals. Over the 5-year period, TC sampling decreased from 22/10,000 patients in 2009 to 8/10,000 patients in 2014 (APC: −14.7% [95% CI −22.3 to −6.4%], P < 0.01), representing a five-fold decrease compared with BC sampling (APC: −2.5% [−5.0 to 0%], P = 0.05; Figure 1). Only 3,561 (20%) TCs displayed any growth of noncontaminant taxa (Figure 2); the most common taxa isolated from TCs were S. aureus (56.5%), Enterobacteriaceae (16%), Candida sp. (13%), and P. aeruginosa (6%). Of the 3,651 positive TCs, 1,631 (46%) were not accompanied by growth in BCs; S. aureus represented 471 (29%) and Candida spp. represented 121 (7%) of isolated TC growth. Of the remaining 1,930 (54%) positive TCs that were accompanied by positive BCs, only 874 (45%) displayed species concordance. ConclusionThe practice of sampling CVC tips for culture is steadily declining at U.S. hospitals. The majority of pathogenic species cultured from CVC tips are either unaccompanied by, or are discordant with, growth in the bloodstream. Barring the isolation of S. aureus or Candida spp. from CVC tips alone, which may represent opportunities to treat, there appears to be limited clinical utility to TC sampling for diagnosing CR-BSI.Disclosures All authors: No reported disclosures.

Efficacy of routine catheter tip culture in a neonatal intensive care unit.

Routine catheter tip cultures are not recommended because some cases of colonization, such as with Staphylococcus aureus, can lead to subsequent bacteremia. To evaluate the safety of colonization without antimicrobial treatment, as well as the effectiveness of routine catheter tip cultures in the neonatal intensive care unit (NICU), we performed a retrospective data analysis in a Japanese community hospital. We reviewed all peripherally inserted central venous catheter tip culture results from the NICU ward between April 2012 and June 2017 and noted outcome (i.e. antimicrobial treatment or subsequent infection). We then performed a cost analysis for routine catheter tip culturing on patients who were symptom free during the study period. Of the 93 positive cases in 80 patients from 1,051 catheter tip cultures, seven patients had suspected infection and were treated with antimicrobials. The other 73 symptom-free, positive patients had no subsequent or exacerbated symptoms indicative of an infection, and did not have antimicrobial treatment. The total cost for catheter tip culturing during the study period was ¥548 731. After excluding patients with symptoms of infection at the time of culture, the efficacy of routine catheter tip cultures on symptom-free patients was estimated to be zero. Symptom-free colonization did not affect clinician management in this study, and all colonized patients without suspected infection were safely managed without antimicrobials. Furthermore, routine catheter tip culturing was not cost-effective; therefore, this practice may be no longer recommended in the NICU.

Bacteriological profile and their antimicrobial susceptibility pattern in central venous catheter tip culture

Background: Bacterial colonization of central venous catheter (CVC) carries risk of developing catheter-related blood stream infections (CRBSI). The purpose of this study is to find out the frequency of colonization of CVC by different bacterial pathogens and their antibiotic sensitivity pattern.Materials and Methods: A total of 53 CVC tip were received in one-year duration for culture and antibiotic sensitivity pattern. The isolated organisms were identified by standard microbiological procedure and subjected to antimicrobial sensitivity.Results: out of 53 CVC tip sent for culture and sensitivity, 21 (39.6%) showed significant growth. Out of 21 culture positive 52.3% were gram negative bacilli, 33.3% were gram positive cocci, 4.8% were Candida spp. Acenitobacter baumannii and Staphylococcus aureus were frequent pathogens isolated. Gram negative bacteria were less sensitive to antibiotics whereas gram positive bacteria were sensitive to Vancomycin.Conclusion: Though various organisms were isolated as colonizer of CVC, Acenitobacter baumannii is the most common colonizer. Antibiotic resistance has already emerged and represents a major problem.

How to use central venous catheter tip cultures

Central venous catheter (CVC) tip cultures are useful in the assessment of a patient with a potential catheter-related bloodstream infection (CRBSI). However, these results can be misleading particularly in the...

Genotypic study documents divergence in the pathogenesis of bloodstream infection related central venous catheters in neonates

ObjectiveTo investigate the pathogenesis of bloodstream infection by Staphylococcus epidermidis, using the molecular epidemiology, in high-risk neonates. MethodsWe conducted a prospective study of a cohort of neonates with bloodstream infection using central venous catheters for more than 24h. “National Healthcare Safety Network” surveillance was conducted. Genotyping was performed by DNA fingerprinting and mecA genes and icaAD were detected by multiplex-PCR. ResultsFrom April 2006 to April 2008, the incidence of bloodstream infection and central venous catheter-associated bloodstream infection was 15.1 and 13.0/1000 catheter days, respectively, with S. epidermidis accounting for 42.9% of episodes. Molecular analysis was used to document the similarity among six isolates of bloodstream infection by S. epidermidis from cases with positive blood and central venous catheter tip cultures. Fifty percent of neonates had bloodstream infection not identified as definite or probable central venous catheter-related bloodstream infection. Only one case was considered as definite central venous catheter-related bloodstream infection and was extraluminally acquired; the remaining were considered probable central venous catheter-related bloodstream infections, with one probable extraluminally and another probable intraluminally acquired bloodstream infection. Additionally, among mecA+ and icaAD+ samples, one clone (A) was predominant (80%). A polyclonal profile was found among sensitive samples that were not carriers of the icaAD gene. ConclusionsThe majority of infections caused by S. epidermidis in neonates had an unknown origin, although 33.3% appeared to have been acquired intraluminally and extraluminally. We observed a polyclonal profile between sensitive samples and a prevalent clone (A) between resistant samples.

Clinical significance of multidrug-resistant Acinetobacter baumannii isolated from central venous catheter tip cultures in patients without concomitant bacteremia

The purpose of this study was to examine the clinical implications of a positive central venous catheter (CVC) tip culture with multidrug-resistant Acinetobacter baumannii (MRAB) in patients without concurrent bacteremia. This retrospective, multicenter study was conducted in 9 teaching hospitals in the Republic of Korea from May 2008 to April 2012. Study subjects included adult patients (aged ≥ 18 y) who yielded an MRAB-positive CVC tip culture without concurrent MRAB bacteremia. All patients were observed for the development of subsequent MRAB bacteremia for 6 months after CVC removal. Multivariable Firth logistic regression analysis was performed to determine predictors independently associated with subsequent MRAB bacteremia. During the study period, subsequent MRAB bacteremia was observed in 18.8% of patients (21/112). Of the 112 patients, 23 (20.5%) did not show systemic inflammatory response syndrome (SIRS). None of the 23 patients without SIRS presented with subsequent MRAB bacteremia. Multivariable logistic regression analysis showed that prior administration of carbapenems (odds ratio (OR) 7.04, 95% confidence interval (CI) 1.43-34.77) or corticosteroids (OR 6.67, 95% CI 1.19-37.44), and C-reactive protein ≥ 40 mg/l (OR 18.11, 95% CI 2.22-148.07) were positive predictive factors. Prior acquisition of MRAB at a site other than the catheter (OR 0.10, 95% CI 0.03-0.39) was a negative predictive factor for developing MRAB bacteremia. Our results suggest that patients with a CVC tip colonized with MRAB should be closely monitored for signs and symptoms of subsequent MRAB bacteremia.

PMO-068 Timing of parenteral nutrition administration set changes: impact on incidence of catheter associated infections

IntroductionPreparations of total parental nutrition (TPN) are stable for 48 h. For patients with requirements <2.5l/24 h individual bags of TPN are delivered for more than 24 h, resulting in...

The First Korean Case of Candidemia due to Candida dubliniensis

Candidemia due to uncommon Candida spp. appears to be increasing in incidence. C. dubliniensis has been increasingly recovered from individuals not infected with HIV. Identification of C. dubliniensis can be problematic in routine clinical practice due to its phenotypic resemblance to C. albicans. We report the first case of C. dubliniensis candidemia in Korea, which occurred in a 64-yr-old woman who presented with partial seizure, drowsiness, and recurrent fever. Germ-tube positive yeast that was isolated from blood and central venous catheter tip cultures formed smooth, white colonies on sheep blood agar and Sabouraud agar plates, indicative of Candida spp. C. dubliniensis was identified using the Vitek 2 system (bioMerieux, USA), latex agglutination, chromogenic agar, and multiplex PCR. The blood isolate was susceptible to flucytosine, fluconazole, voriconazole, and amphotericin B. After removal of the central venous catheter and initiation of fluconazole treatment, the patient's condition gradually improved, and she was cleared for discharge from our hospital. Both clinicians and microbiologists should be aware of predisposing factors to C. dubliniensis candidemia in order to promote early diagnosis and appropriate treatment.

Culture Positivity of CVCs Used for TPN: Investigation of an Association with Catheter-Related Infection and Comparison of Causative Organisms between ICU and Non-ICU CVCs

A relationship between central venous catheter (CVC) tip colonisation and catheter-related blood-stream infection (CRBSI) has been suggested. We examined culture positivity of CVC tips (colonised and infected CVCs) in a total parenteral nutrition (TPN) population. Our aims were to define the relationship between culture positivity and CRBSI, and to compare causative organisms between culture positive and CRBSI CVCS, and between ward and ICU CVCs. All patients receiving TPN via non-tunnelled CVCs during the study (1997–2009) were included. All CVC tips were analysed. Data were collated contemporaneously. A TPN audit committee determined whether CVC tip culture positivity reflected colonisation/CRBSI using CDC criteria. 1,392 patients received TPN via 2,565 CVCs over 15,397 CVC days. 25.4% of CVCs tips were culture positive, of these 32% developed CRBSI. There was a nonsignificant trend of higher Gram negative Bacilli isolation in ICU CVCs (P = 0.1), ward CVCs were associated with higher rates of staphylococcal isolation (P = 0.01). A similar pattern of organisms were cultured from CRBSI and culture positive CVCs. The consistent relationship between CRBSI and culture positive CVCs, and similar pattern of causative organisms further supports an aetiological relationship between culture positive CVC tips and CRBSI, supporting the contention that CVC culture-positivity may be a useful surrogate marker for CRBSI rates.

How Should Long-Term Tunneled Central Venous Catheters Be Managed in Microbiology Laboratories in Order To Provide an Accurate Diagnosis of Colonization?

Guidelines recommend the roll-plate technique for short-term central venous catheter (CVC) tip cultures. However, the issue of whether the roll-plate technique is better than the sonication method for long-term CVCs remains unresolved. In addition, no data are available for predicting the value of direct Gram staining in anticipating catheter colonization or catheter-related bloodstream infection (CRBSI) in these long-term CVCs. Our objectives were to compare the roll-plate technique and the sonication method and to define the validity values of Gram staining for the prediction of colonization and CRBSI in patients with long-term tunneled CVCs. During the study period, all tunneled CVCs removed at our institution were prospectively and routinely sent to the microbiology laboratory for Gram staining (first) and tip culture (the Maki technique and sonication, in a random order). We received 149 tunneled CVCs, 39 (26.2%) of which were colonized and 11 (7.4%) of which were associated with CRBSI. Overall, the roll-plate method detected 94.9% of the colonized catheters, whereas sonication detected only 43.6% (P < 0.001). The validity values of Gram staining for the detection of colonization and CRBSI were as follows: a sensitivity of 35.9% to 60.0%, a specificity of 100% to 94.2%, a positive predictive value of 100% to 42.9%, and a negative predictive value of 81.5% to 97.0%. The roll-plate technique proved to be better than sonication for the detection of bacteria in long-term tunneled CVCs. Gram staining of the tips of tunneled CVCs can anticipate a positive culture and rule out CRBSI. In our opinion, direct Gram staining should be incorporated into routine microbiological assessments of long-term catheter tips.

Development of bacteraemia or fungaemia after removal of colonized central venous catheters in patients with negative concomitant blood cultures

There are limited data on the clinical significance of -positive central venous catheter (CVC) tip cultures associated with concomitant negative blood cultures performed at the time of CVC removal. A retrospective cohort study of all patients who yielded isolated -positive CVC tip cultures was conducted in a tertiary-care hospital with 2200 beds during a 10-year period. All patients with isolated -positive CVC tip cultures were observed for the development of subsequent bacteraemia or fungaemia between 2 and 28 days after CVC removal. An isolated -positive CVC tip culture was defined as a case in which (i) a CVC tip culture yielded ≥15 colonies using a semiquantitative culture method and (ii) at least two sets of blood samples revealed no organism at, or close to, the time of CVC removal (48 h before to 48 h after CVC removal). During the study period, 312 patients with isolated -positive CVC cultures were enrolled. Eight (2.6%; 95% CI 1.2–5.1) of the 312 patients yielding isolated bacterial or fungal CVC tip cultures developed subsequent bloodstream infection (BSI) caused by the same species as that isolated from the tip culture (Staphylococcus aureus, 1: Enterococcus spp.; 2: Pseudomonas aeruginosa; and 3: Candida spp.). Among 125 patients from whose CVC tips the above four organisms were grown, seven (12.3%) of 57 patients who did not receive appropriate antibiotic therapy within 48 h after CVC removal subsequently developed BSI, but only one (1.5%) of 68 patients who did receive appropriate therapy developed BSI (OR 0.11, p 0.02).

Deposits on the intraluminal surface and bacterial growth in central venous catheters

Central venous catheter (CVC) tip and blood cultures are generally used to diagnose a catheter-related infection. Such methodology does not confirm the presence of bacterial colonisation on parts of CVCs other than the CVC tip. In order to assess the extent of bacterial colonisation, 10 catheters were examined in detail from patients admitted to intensive care unit. Swabs from the lumen at several sites (hub, indwelling and non-indwelling) were cultured and the intraluminal surface of the device subjected to scanning electron microscopy (SEM). Bacteria were detected on five out of 10 catheters (50%), and bacterial contamination of CVCs was common in the hub area of the device. Deposits (crystallisation) that differed from bacterial colonisation or biofilm were observed on the intraluminal surface of used CVCs. SEM showed bacteria firmly anchored to the deposits. Experimental flow studies demonstrated that deposits were more likely to appear after exposure to solutions such as total parenteral nutrition rather than distilled water. These deposits facilitated bacterial colonisation 30 times more than CVCs free from deposits.

Are central venous catheter tip cultures reliable after 6-day refrigeration?

Present guidelines recommend culturing only central venous catheter (CVC) tips from patients with suspected catheter-related bloodstream infection (CR-BSI). However, a high proportion of these suspicions are not confirmed. Moreover, CVC tip culture increases laboratory workload, and reports of colonization may be meaningless or misleading for the clinician. Our working hypothesis was that CVC tips should be refrigerated and cultured only in patients with positive blood cultures. We evaluated the effect of 6-day refrigeration of 215 CVC tips. We selected all the catheters with a significant count according to the Maki's roll-plate technique and randomly assigned them to 2 groups. In group A, the catheters were recultured after 24 h of refrigeration, and in group B, the catheters were recultured after 6 days more of refrigeration, so that the refrigeration time evaluated would be of 6 days. The yield of refrigerated CVC tips that grow significant colony counts of primary culture in group B was compared with the yield of refrigerated catheter tips in group A. The difference showed that 6-day refrigeration reduced the number of significant CVCs by 15.2%. Only 61 CVCs were obtained from patients with CR-BSI, and in most of them, blood cultures were already positive before CVC culture, so only 0.91% of the CR-BSI episodes would have been misdiagnosed as culture negative after refrigeration. Refrigeration of CVC tips sent for culture and culturing only those from patients with positive blood cultures reduce the workload in the microbiology laboratory without misdiagnosing CR-BSI.

Do antibiotics administered at the time of central venous catheter removal interfere with the evaluation of colonization?

Catheter colonization is commonly used as an end point in studies on central venous catheter (CVC) infections. This study aimed at comparing the rates of catheter colonization in patients according to the administration of antibiotics at removal. Prospective study over a 5-year period. All patients with a CVC removed without suspicion of CVC infection were included. An adult medical/surgical intensive care unit at a university teaching hospital. A total of 472 patients with CVC inserted for a mean CVC duration of 6.0 +/- 3.7 days were included. Antibiotics at removal was defined as antibiotics administered within 48[Symbol: see text]h before CVC removal, and CVC colonization as catheter tip culture yielding > or = 10(3) colony-forming units per milliliter. None. Of 472 patients, 302 (64%) were receiving antibiotics at removal. The number of CVC colonizations per number of CVCs inserted was 4.7% (22 of 472) and the number of CVC colonizations per 1000 CVC days was 8.0. Administration of antibiotics at removal was associated with a lower risk of CVC colonization. Irrespective of CVC duration, CVC colonization rate differed between patients with or without antibiotics at removal (Kaplan-Meier test, p=0.04). The proportion of patients with antibiotics at time of removal should be taken into account when interpreting the results of surveys and trials using the quantitative CVC tip culture to define CVC colonization as an end point.

Clinical significance of isolated Staphylococcus aureus central venous catheter tip cultures

This retrospective cohort study examined the clinical significance of isolated Staphylococcus aureus central venous catheter (CVC) tip cultures (i.e., positive tip cultures without concomitant positive blood cultures). Subsequent S. aureus bacteraemia was found in nine (12%) of 77 patients at a median time of 4 days after CVC removal. A high co-morbidity score and no effective antibiotic treatment within 48 h of CVC removal were independent risk-factors for septic complications following multivariate analysis. A matched case-control study that compared the above cohort with patients with CVC tip cultures negative for S. aureus supported the significance of these findings.