Chlorhexidine compared with povidone-iodine as skin preparation before blood culture. A randomized, controlled trial

BD Chloraprep™ ("2 % chlorhexidine with 70 % isopropyl alcohol") versus povidone iodine plus alcohol, for prevention of blood culture contamination at children: An investigator-initiated, open-label, single centre, randomized controlled trial

INTRODUCTION

One of the important problems that lower the diagnostic value of blood culture is contamination with skin organisms. The povidone-iodine, alcohol, and chlorhexidine gluconate alcohol are used for disinfection prior to blood sampling for culture.

METHODS

The investigator-initiated, open label, single centre, randomised trial compared blood culture contamination rates between two groups of patients in which using a povidone iodine skin-preparation process with the contamination rate for using "2 % chlorhexidine with 70 % isopropyl alcohol" skin-disinfection. The patients who required sampling for blood cultures were included in the study and study period was from 15 March 2023 to 15 July 2023.

RESULTS

A total of 400 blood cultures were obtained during the study, including 133 in the study group and 267 in the control group. In the total blood cultures, 11.75 % (n = 47) had microorganism isolation. Among them 39 (9.75 %) were contaminants and 8 (2 %) of them were true pathogens. The contaminant microorganisms were as following; 34 coagulase-negative Staphylococci, 3 Micrococcus spp, and 2 Streptococci viridans. The blood culture contamination rate in the study group was 5.3 % (n = 7) and 12.0 % (n = 32) in the control group, and significantly lower in the study group (p = 0.033). There is no significant difference regarding skin related side effects between two groups.

CONCLUSIONS

This study, showed that 2 % chlorhexidine gluconate in 70 % isopropyl alcohol is more efficacious in children than 10 % povidone-iodine preparations for disinfecting the skin prior to blood specimen collection for prevention of blood culture contamination.

Effect of the introduction of a management bundle for blood culture collection

BACKGROUND

Inappropriate blood collection subjected to blood culture (BC) causes BC contamination and may complicate the diagnose is of infectious diseases. Therefore, we developed a bundle based on the guideline recommendations for appropriate blood collection and examined the effects of bundle introduction.

METHODS

We performed a retrospective analysis of BC samples to determine the contamination rates before and after introducing the BC bundle. We also analyzed the correlation between the compliance rate of the bundle and contamination rate, and between each bundle element and contamination.

RESULTS

After the introduction of the bundle, the contamination rate was significantly reduced from 5.4% ± 0.9% to 1.7± 0.7% (P < .01). The compliance rate of the bundle was significantly associated with a lower contamination rate (P < .01). Multivariable logistic regression showed that collection from superficial veins of the cubital fossa (odds ratio [OR], 0.25; 95% confidence interval [CI], 0.13-0.51, P < .01) and disinfection of the skin at the blood collection site with 1% chlorhexidine alcohol swab (OR, 0.41; 95% CI, 0.25-0.68, P < .01) were significantly associated with lower contamination.

CONCLUSIONS

This study suggests that the introduction of the BC bundle significantly reduced the contamination rate, and bundle compliance was associated with a lower contamination rate.

Identification of the main contributors to blood culture contamination at a tertiary care academic medical center

Background

Blood culture contamination poses an issue to all hospital systems worldwide because of the associated costs of extended length of stays, unnecessary antibiotic therapy, and additional laboratory testing that are preventable with proper handling and collection techniques.

Methods

In our study, multiple units, staff, and collection methods were compared to determine the primary culprits of contamination from a tertiary care academic medical center, which includes a pediatric hospital and both adult and pediatric emergency departments.

Results

Over 33 months, 2,083 out of 88,322 total blood cultures collected were contaminated, with an overall contamination rate of 2.4%. A moderate positive correlation was found between the monthly total number of cultures and monthly contamination rate (r = 0.411 P < .01). The most notable factors associated with contamination were found to be phlebotomy teams (2.7%) (P < .01), peripheral draws (2.3%) (P <.01), adult emergency departments (2.6%) (P < .01), and pediatric intensive care units (2.7%) (P < .01). A positive correlation was present between the number of hospital beds per unit and unit contamination rates (r = 0.429 P < .01).

Conclusion

Our results were used to make recommendations for decreasing the rate of blood culture contamination in this institution, which includes acknowledgement of an overwhelmed staff and mandatory periodic training on acceptable aseptic technique and contamination awareness. Understanding the factors contributing to blood culture contamination can aid efforts to reduce contamination rates.

Comparison of Efficacy of 2% Chlorhexidine Gluconate-Alcohol and 10% Povidone-Iodine-Alcohol against Catheter-Related Bloodstream Infections and Bacterial Colonization at Central Venous Catheter Insertion Sites: A Prospective, Single-Center, Open-Label, Crossover Study

An effective antiseptic agent is an essential component of a central venous catheter (CVC) care bundle, to protect against catheter-related bloodstream infections (CRBSIs). We conducted a trial to compare the incidences of CRBSI and the growth of insertion site flora in patients with CVC using 2% chlorhexidine gluconate−alcohol (CHG) or 10% povidone-iodine−alcohol (PVI) in the CVC care bundle. Patients who were admitted to two medical intensive care units (ICUs) and had CVC placement for >48 h were enrolled. Using a two-way crossover design with two six-month interventions, the ICUs were assigned to use either CHG or PVI in their care bundles. A total of 446 catheters in 390 subjects were enrolled in the study. The detection rate of flora was greater in the PVI group on both day 7 (26.6% versus 6.3%, p < 0.001) and day 14 (43.2% versus 15.8%, p < 0.001). The incidence rate of CRBSI was higher in the PVI group compared to the CHG group (2.15 vs. 0 events per 1000-catheter-days, p = 0.001), although the significance was lost in the multivariate analysis. In conclusion, 2% CHG was superior to 10% PVI in the CVC care bundle in terms of the inhibition of skin flora growth at CVC insertion sites and was potentially associated with lower incidence rates of CRBSI.

Effectiveness of broad-spectrum antiseptics in production of disinfected maggots of Lucilia sericata for use in wound debridement therapy

The establishment of low-cost, effective, safe and practical methods is necessary to increase the use of larval therapy in wound care. Although studies on external disinfection of calliphorid eggs have been reported, many studies lack data on the effect of disinfection on egg viability and the microorganisms found before disinfection. Therefore, the main objective of this study was to compare three antiseptic solutions, that is, chlorhexidine (5%), Dakin's solution (0.5% NaOCl) and povidone-iodine (10%), in terms of their ability to disinfect Lucilia sericata eggs. Egg viability after disinfection and microorganisms present on the eggs and larvae before and after treatment were also examined. None of the antiseptics had a significant effect on egg viability. Disinfection of L. sericata eggs with 0.5% NaOCl was the best method, as sterility tests showed no contamination. Escherichia coli, Bacillus subtilis and Proteus mirabilis were present in all cultures isolated from the non-disinfected eggs and larvae, while Enterococcus faecium, Enterococcus faecalis, Morganella morganii, Corynebacterium spp. and Providencia stuartii were isolated from more than half of the same cultures. Sterility testing of medicinal maggots after disinfection is crucial to prevent secondary infections and achieve a positive therapeutic outcome.

Comparison of 0.5% chlorhexidine gluconate alcohol with 10% povidone-iodine for skin disinfection in children to prevent blood culture contamination

INTRODUCTION

Various disinfectants, such as povidone iodine (PVI)¹, alcohol preparations, and chlorhexidine gluconate ethanol (CHG-ALC), are used for disinfection prior to blood sampling for culture.

METHODS

This retrospective cohort study compared the usefulness and effectiveness of CHG-ALC and PVI in pediatric venipuncture. We applied 0.5% w/v CHG-ALC or 10% PVI as an antiseptic for phlebotomies on pediatric outpatients and inpatients with suspected bacterial infection between November 2017 and April 2019. We conducted logistic regression analysis to define the differences associated with the choice of disinfectant, collection site, and the staff member collecting the blood sample (explanatory variables) and the presence of contamination (objective variable). Based on these results, we performed propensity score matching.

RESULTS

The total number of specimens was 1460. The propensity score matching indicated that CHG-ALC reduced the incidence of blood culture contamination more effectively than PVI (0.4%, 2/479 cultures versus 2.5%, 12/479 cultures; relative risk, 0.163 [95% confidence interval, 0.036 to 0.733]; P = 0.012). There were no differences in the contamination rates between cultures of blood drawn from a vascular catheter and those of blood obtained percutaneously. Higher contamination rates were found when junior residents performed the venipuncture.

CONCLUSIONS

Compared with PVI, CHG-ALC dries rapidly with no pigmentation and has a long-lasting antiseptic effect. Overall, CHG-ALC skin preparations were more efficacious than the PVI preparations for blood sampling in children.

Time to blood cultures positivity of microorganisms using a continuous-monitoring automated blood cultures system

Background

Previous studies showed that clinically significant pathogens were detected within 3 days of incubation using a continuous monitoring automated blood culture instrument.

Objectives

To determine time to blood culture positivity (TTP) of microorganisms using a BD BACTEC™ FX.

Methods

A cross-sectional study was conducted at Maharaj Nakorn Chiang Mai Hospital, Thailand from October to November 2014.

Results

One-hundred and eighty-one patients with 195 episodes of infection and 436 cultures were included in the analysis. Among 181 patients, 55.2% were male and the median age was 61 years (interquartile range (IQR) 50, 76). Of the 195 episodes of infections, the most common source was genitourinary tract (15.4%). Overall, the median TTP was 17 hours (IQR 11.5, 24.5), the shortest TTP was observed in Streptococcus agalactiae. Four-hundred and seventy-eight cultures (97.6%) and all (100%) were detected at 3 days and 5 days of incubation. Factors associated with TTP ≤24 hour were blood drawn from patients who had hematologic malignancy (odds ratio (OR) 9.6, 95% confidence interval (CI) 1.2, 74.3, P = 0.030), endocarditis and vascular infection (OR 8.7, 95% CI 1.1, 67.2, P = 0.038), thrombocytopenia (OR 2.4, 95% CI 1.3, 4.4, P = 0.004), clinical of systemic inflammatory response syndrome (SIRS) (OR 2.3, 95% CI 1.2, 4.5, P = 0.014), and not receiving antimicrobials within 72 hours before cultures taken (OR 2.2, 95% CI 1.4, 3.6, P < 0.001).

Conclusions

TTP varied depends upon the pathogens and clinical settings. However, bacteria were isolated from almost, but not all of the blood cultures within 3 days of incubation.

Practical Guidance for Clinical Microbiology Laboratories: A Comprehensive Update on the Problem of Blood Culture Contamination and a Discussion of Methods for Addressing the Problem

In this review, we present a comprehensive discussion of matters related to the problem of blood culture contamination. Issues addressed include the scope and magnitude of the problem, the bacteria most often recognized as contaminants, the impact of blood culture contamination on clinical microbiology laboratory function, the economic and clinical ramifications of contamination, and, perhaps most importantly, a systematic discussion of solutions to the problem. We conclude by providing a series of unanswered questions that pertain to this important issue.

Identification of Gram negative non-fermentative bacteria: How hard can it be?

INTRODUCTION

The prevalence of bacteremia caused by Gram negative non-fermentative (GNNF) bacteria has been increasing globally over the past decade. Many studies have investigated their epidemiology but focus on the common GNNF including Pseudomonas aeruginosa and Acinetobacter baumannii. Knowledge of the uncommon GNNF bacteremias is very limited. This study explores invasive bloodstream infection GNNF isolates that were initially unidentified after testing with standard microbiological techniques. All isolations were made during laboratory-based surveillance activities in two rural provinces of Thailand between 2006 and 2014.

METHODS

A subset of GNNF clinical isolates (204/947), not identified by standard manual biochemical methodologies were run on the BD Phoenix automated identification and susceptibility testing system. If an organism was not identified (12/204) DNA was extracted for whole genome sequencing (WGS) on a MiSeq platform and data analysis performed using 3 web-based platforms: Taxonomer, CGE KmerFinder and One Codex.

RESULTS

The BD Phoenix automated identification system recognized 92% (187/204) of the GNNF isolates, and because of their taxonomic complexity and high phenotypic similarity 37% (69/187) were only identified to the genus level. Five isolates grew too slowly for identification. Antimicrobial sensitivity (AST) data was not obtained for 93/187 (50%) identified isolates either because of their slow growth or their taxa were not in the AST database associated with the instrument. WGS identified the 12 remaining unknowns, four to genus level only.

CONCLUSION

The GNNF bacteria are of increasing concern in the clinical setting, and our inability to identify these organisms and determine their AST profiles will impede treatment. Databases for automated identification systems and sequencing annotation need to be improved so that opportunistic organisms are better covered.

Best Practices of Blood Cultures in Low- and Middle-Income Countries

Bloodstream infections (BSI) have a substantial impact on morbidity and mortality worldwide. Despite scarcity of data from many low- and middle-income countries (LMICs), there is increasing awareness of the importance of BSI in these countries. For example, it is estimated that the global mortality of non-typhoidal Salmonella bloodstream infection in children under 5 already exceeds that of malaria. Reliable and accurate diagnosis of these infections is therefore of utmost importance. Blood cultures are the reference method for diagnosis of BSI. LMICs face many challenges when implementing blood cultures, due to financial, logistical, and infrastructure-related constraints. This review aims to provide an overview of the state-of-the-art of sampling and processing of blood cultures, with emphasis on its use in LMICs. Laboratory processing of blood cultures is relatively straightforward and can be done without the need for expensive and complicated equipment. Automates for incubation and growth monitoring have become the standard in high-income countries (HICs), but they are still too expensive and not sufficiently robust for imminent implementation in most LMICs. Therefore, this review focuses on "manual" methods of blood culture, not involving automated equipment. In manual blood cultures, a bottle consisting of a broth medium supporting bacterial growth is incubated in a normal incubator and inspected daily for signs of growth. The collection of blood for blood culture is a crucial step in the process, as the sensitivity of blood cultures depends on the volume sampled; furthermore, contamination of the blood culture (accidental inoculation of environmental and skin bacteria) can be avoided by appropriate antisepsis. In this review, we give recommendations regarding appropriate blood culture sampling and processing in LMICs. We present feasible methods to detect and speed up growth and discuss some challenges in implementing blood cultures in LMICs, such as the biosafety aspects, supply chain and waste management.

A Novel, Widespread qacA Allele Results in Reduced Chlorhexidine Susceptibility in Staphylococcus epidermidis

Chlorhexidine gluconate (CHG) is a topical antiseptic widely used in health care settings. In Staphylococcus spp., the pump QacA effluxes CHG, while the closely related QacB cannot due to a single amino acid substitution. We characterized 1,050 cutaneous Staphylococcus isolates obtained from 173 pediatric oncology patients enrolled in a multicenter CHG bathing trial. CHG susceptibility testing revealed that 63 (6%) of these isolates had elevated CHG MICs (≥4 μg/ml). Screening of all 1,050 isolates for the qacA/B gene (the same qac gene with A or B allele) by restriction fragment length polymorphism (RFLP) yielded 56 isolates with a novel qacA/B RFLP pattern, qacA/B₂₇₃ The CHG MIC was significantly higher for qacA/B₂₇₃ -positive isolates (MIC₅₀, 4 μg/ml; MIC range, 0.5 to 4 μg/ml) than for other qac groups: qacA-positive isolates (n = 559; MIC₅₀, 1 μg/ml; MIC range, 0.5 to 4 μg/ml), qacB-positive isolates (n = 17; MIC₅₀, 1 μg/ml; MIC range, 0.25 to 2 μg/ml), and qacA/B-negative isolates (n = 418, MIC₅₀, 1 μg/ml; MIC range, 0.125 to 2 μg/ml) (P = 0.001). A high proportion of the qacA/B₂₇₃ -positive isolates also displayed methicillin resistance (96.4%) compared to the other qac groups (24.9 to 61.7%) (P = 0.001). Whole-genome sequencing revealed that qacA/B₂₇₃ -positive isolates encoded a variant of QacA with 2 amino acid substitutions. This new allele, named qacA4, was carried on the novel plasmid pAQZ1. The qacA4-carrying isolates belonged to the highly resistant Staphylococcus epidermidis sequence type 2 clone. By searching available sequence data sets, we identified 39 additional qacA4-carrying S. epidermidis strains from 5 countries. Curing an isolate of qacA4 resulted in a 4-fold decrease in the CHG MIC, confirming the role of qacA4 in the elevated CHG MIC. Our results highlight the importance of further studying qacA4 and its functional role in clinical staphylococci.

Diagnosis and treatment of catheter-related bloodstream infection: Clinical guidelines of the Spanish Society of Infectious Diseases and Clinical Microbiology and (SEIMC) and the Spanish Society of Spanish Society of Intensive and Critical Care Medicine and Coronary Units (SEMICYUC)

Catheter-related bloodstream infections (CRBSI) constitute an important cause of hospital-acquired infection associated with morbidity, mortality, and cost. The aim of these guidelines is to provide updated recommendations for the diagnosis and management of CRBSI in adults. Prevention of CRBSI is excluded. Experts in the field were designated by the two participating Societies (the Spanish Society of Infectious Diseases and Clinical Microbiology and [SEIMC] and the Spanish Society of Spanish Society of Intensive and Critical Care Medicine and Coronary Units [SEMICYUC]). Short-term peripheral venous catheters, non-tunneled and long-term central venous catheters, tunneled catheters and hemodialysis catheters are covered by these guidelines. The panel identified 39 key topics that were formulated in accordance with the PICO format. The strength of the recommendations and quality of the evidence were graded in accordance with ESCMID guidelines. Recommendations are made for the diagnosis of CRBSI with and without catheter removal and of tunnel infection. The document establishes the clinical situations in which a conservative diagnosis of CRBSI (diagnosis without catheter removal) is feasible. Recommendations are also made regarding empirical therapy, pathogen-specific treatment (coagulase-negative staphylococci, Staphylococcus aureus, Enterococcus spp., Gram-negative bacilli, and Candida spp.), antibiotic lock therapy, diagnosis and management of suppurative thrombophlebitis and local complications.

[Assessment of an educational intervention regarding blood cultures as process indicators in an emergency department in Argentina]

OBJECTIVE

The aim of this study was to describe 2 process indicators related to taking blood cultures (BC) in an Adult Emergency Department of a tertiary university hospital in Buenos Aires,and to describe the changes after a series of educational activities for health professionals was implemented during May 2016 as regards the appropriate indication of BC and the proper collection technique.

MATERIALS AND METHODS

A retrospective cohort study was designed to assess its effectiveness, which consecutively included all patients admitted during 2015-2016. The BC request rate was used as a process indicator, and the percentage of contaminated BCs and the true positives rate were used as quality indicators. Both were measured monthly and prospectively during the period of study.

RESULTS

The annual adjusted rate of BC requests was 4.9% (95% CI 4.8-5) in 2015 and 2.9% (95% CI 2.8-2.9) in 2016. The rate of false positive (contaminated) BCs was 4.5% in 2015 and 4.3% after the educational intervention. The true positive BCs were 8.3% in 2015 and 12% post-intervention.

CONCLUSIONS

These findings prove how important and effective the educational interventions are.

Effect of a training programme on blood culture contamination rate in critical care

Blood culture contamination can occur from extraction to processing; its rate should not exceed 3%.

OBJECTIVE

To evaluate the impact of a training programme on the rate of contaminated blood cultures after the implementation of sample extraction recommendations based on the best evidence.

METHOD

Prospective before-after study in a polyvalent intensive care unit with 18 beds. Two phases were established (January-June 2012, October 2012-October 2015) with a training period between them. Main recommendations: sterile technique, surgical mask, double skin disinfection (70° alcohol and 2% alcoholic chlorhexidine), 70° alcohol disinfection of culture flasks and injection of samples without changing needles. Including all blood cultures of patients with extraction request.

VARIABLES

demographic, severity, pathology, reason for admission, stay and results of blood cultures (negative, positive and contaminated). Basic descriptive statistics: mean (standard deviation), median (interquartile range) and percentage (95% confidence interval). Calculated contamination rates per 100 blood cultures extracted. Bivariate analysis between periods.

RESULTS

Four hundred and eight patients were included. Eight hundred and forty-one blood cultures were taken, 33 of which were contaminated. In the demographic variables, severity, diagnosis and stay of patients with contaminated samples, no differences were observed from those with uncontaminated samples. Pre-training vs post-training contamination rates: 14 vs 5.6 per 100 blood cultures extracted (P=.00003).

CONCLUSION

An evidence-based training programme reduced the contamination of samples. It is necessary to continue working on the planning of activities and care to improve the detection of pollutants and prevent contamination of samples.

A survey of international antisepsis procedures for neuraxial catheterisation in labour

BACKGROUND

Neuraxial analgesia during labour is a mainstay of anaesthetic practice globally. Despite the potential for significant neurological and infectious complications, international antisepsis practices for neuraxial anaesthesia vary widely.

AIMS

The primary aim of this study was to clarify international antisepsis practices prior to neuraxial analgesia in labour. The secondary aim was to determine an approximate international incidence of neuraxial infections and neurological complications secondary to neuraxial analgesia techniques in labour.

MATERIALS AND METHODS

Heads of Departments of Anaesthesiology were invited to complete an online questionnaire exploring antisepsis practices and complications of neuraxial catheterisation. Data from 151 institutions in 13 countries were collected over 11months.

RESULTS

Data were collected for an estimated 6008540 deliveries and 3770800 neuraxial catheterisations. The average annual birth rate per institution was 3979 births, with an average of 2497 neuraxial catheterizations (representing 62.8% of deliveries). Forty-nine percent of responders reported always wearing sterile gowns for the procedure, whereas 47.7% never wear gowns. Chlorhexidine was used by 88.1% of those surveyed, and 96.7% always wore facemasks. Thirty-four percent of institutions reported infectious complications over a 10-year period. Ninety neuraxial infections were estimated, giving an approximate incidence of 1:41898 catheterisations (2.39 infections per 100000 catheterisations). A total of 202 neurological complications were reported, with an approximate incidence of 1:18667 catheterisations (5.36 neurological complications per 100000 catheterisations).

CONCLUSION

The survey demonstrated marked variation in aseptic practice between both responding centres and countries. The incidence of infectious and neurological complications secondary to neuraxial catherisation in labour has been approximated.

Isopropyl alcohol is as efficient as chlorhexidine to prevent contamination of blood cultures

BACKGROUND

False-positive blood cultures can lead to unnecessary risks and misuse of antibiotics; to reduce rates of false-positives, it would be useful to determine whether use of an antiseptic with a prolonged effect is required.

METHODS

Clinical study of efficacy (blinded and randomized) to compare the rate of blood culture contamination when skin antisepsis was performed with 70% isopropyl alcohol or 2% chlorhexidine gluconate in 70% isopropyl alcohol in 2 hospitals. Patients aged 16 years or older with suspected bloodstream infection who were allocated in the emergency room, internal medicine ward, or intensive care unit were included.

RESULTS

Five of 563 (0.9%) blood cultures from the isopropyl arm and 10 of 539 (1.9%) from the chlorhexidine arm were contaminated. No significant differences were observed among the rate of contamination (χ²=1.27; P = .3) or the relative risk of contamination (relative risk = 2.09; 95% confidence interval, 0.72-6.07; P = .2).

CONCLUSIONS

The rates of blood contamination were not different when isopropyl alcohol and chlorhexidine were compared. Isopropyl alcohol could be used for skin antisepsis before blood collection.

Chlorhexidine versus Tincture of Iodine for Reduction of Blood Culture Contamination Rates: a Prospective Randomized Crossover Study

Blood cultures (BCs) are the standard method for diagnosis of bloodstream infections (BSIs). However, the average BC contamination rate (CR) in U.S. hospitals is 2.9%, potentially resulting in unnecessary antibiotic use and excessive therapy costs. Several studies have compared various skin antisepsis agents without a clear consensus as to which agent is most effective in reducing contamination. A prospective, randomized crossover study directly comparing blood culture contamination rates using chlorhexidine versus iodine tincture for skin antisepsis was performed at Robert Wood Johnson University Hospital (RWJUH). Eight nursing units at RWJUH were provided with blood culture kits containing either chlorhexidine (CH) or iodine tincture (IT) for skin antisepsis prior to all blood culture venipunctures, which were obtained by nurses or clinical care technicians. At quarterly intervals, the antiseptic agent used on each nursing unit was switched. Analyses of positive BCs were performed to distinguish true BSIs from contaminants. Of the 6,095 total BC sets obtained from the participating nursing units, 667 (10.94%) were positive and 238 (3.90%) were judged by the investigators to be contaminated. Of the 3,130 BCs obtained using IT, 340 (10.86%) were positive and 123 (3.93%) were contaminated. Of 2,965 BCs obtained using CH, 327 (11.03%) were positive and 115 (3.88%) were contaminated. The rates of contaminated BCs were not statistically significant between the two antiseptic agents (P = 1.0). We conclude that CH and IT are equivalent agents for blood culture skin antisepsis.

Best Clinical Practice: Blood Culture Utility in the Emergency Department

BACKGROUND

Bacteremia affects 200,000 patients per year, with the potential for significant morbidity and mortality. Blood cultures are considered the most sensitive method for detecting bacteremia and are commonly obtained in patients with fever, chills, leukocytosis, focal infections, and sepsis.

OBJECTIVE

We sought to provide emergency physicians with a review of the literature concerning blood cultures in the emergency department.

DISCUSSION

The utility of blood cultures has been a focus of controversy, prompting research evaluating effects on patient management. Bacteremia is associated with increased mortality, and blood cultures are often obtained for suspected infection. False-positive blood cultures are associated with harm, including increased duration of stay and cost. This review suggests that blood cultures are not recommended for patients with cellulitis, simple pyelonephritis, and community-acquired pneumonia, because the chance of a false-positive culture is greater than the prevalence of true positive cultures. Blood cultures are recommended for patients with sepsis, meningitis, complicated pyelonephritis, endocarditis, and health care-associated pneumonia. Clinical prediction rules that predict true positive cultures may prove useful. The clinical picture should take precedence. If cultures are obtained, two bottles of ≥7 mL should be obtained from separate peripheral sites.

CONCLUSIONS

Blood cultures are commonly obtained but demonstrate low yield in cellulitis, simple pyelonephritis, and community-acquired pneumonia. The Shapiro decision rule for predicting true bacteremia does show promise, but clinical gestalt should take precedence. To maximize utility, blood cultures should be obtained before antibiotic therapy begins. At least two blood cultures should be obtained from separate peripheral sites.

A Multicenter Evaluation of Blood Culture Practices, Contamination Rates, and the Distribution of Causative Bacteria

BACKGROUND

The prognostic value of blood culture testing in the diagnosis of bacteremia is limited by contamination.

OBJECTIVES

In this multicenter study, the aim was to evaluate the contamination rates of blood cultures as well as the parameters that affect the culture results.

MATERIALS AND METHODS

Sample collection practices and culture data obtained from 16 university/research hospitals were retrospectively evaluated. A total of 214,340 blood samples from 43,254 patients admitted to the centers in 2013 were included in this study. The blood culture results were evaluated based on the three phases of laboratory testing: the pre-analytic, the analytic, and the post-analytic phase.

RESULTS

Blood samples were obtained from the patients through either the peripheral venous route (64%) or an intravascular catheter (36%). Povidone-iodine (60%) or alcohol (40%) was applied to disinfect the skin. Of the 16 centers, 62.5% have no dedicated phlebotomy team, 68.7% employed a blood culture system, 86.7% conducted additional studies with pediatric bottles, and 43.7% with anaerobic bottles. One center maintained a blood culture quality control study. The average growth rate in the bottles of blood cultures during the defined period (1259 - 26,400/year) was 32.3%. Of the growing microorganisms, 67% were causative agents, while 33% were contaminants. The contamination rates of the centers ranged from 1% to 17%. The average growth time for the causative bacteria was 21.4 hours, while it was 36.3 hours for the contaminant bacteria. The most commonly isolated pathogens were Escherichia coli (22.45%) and coagulase-negative staphylococci (CoNS) (20.11%). Further, the most frequently identified contaminant bacteria were CoNS (44.04%).

CONCLUSIONS

The high contamination rates were remarkable in this study. We suggest that the hospitals' staff should be better trained in blood sample collection and processing. Sterile glove usage, alcohol usage for disinfection, the presence of a phlebotomy team, and quality control studies may all contribute to decreasing the contamination rates. Health policy makers should therefore provide the necessary financial support to obtain the required materials and equipment.

Skin antisepsis with chlorhexidine-alcohol versus povidone iodine-alcohol, with and without skin scrubbing, for prevention of intravascular-catheter-related infection (CLEAN): an open-label, multicentre, randomised, controlled, two-by-two factorial trial

BACKGROUND

Intravascular-catheter-related infections are frequent life-threatening events in health care, but incidence can be decreased by improvements in the quality of care. Optimisation of skin antisepsis is essential to prevent short-term catheter-related infections. We hypothesised that chlorhexidine-alcohol would be more effective than povidone iodine-alcohol as a skin antiseptic to prevent intravascular-catheter-related infections.

METHODS

In this open-label, randomised controlled trial with a two-by-two factorial design, we enrolled consecutive adults (age ≥18 years) admitted to one of 11 French intensive-care units and requiring at least one of central-venous, haemodialysis, or arterial catheters. Before catheter insertion, we randomly assigned (1:1:1:1) patients via a secure web-based random-number generator (permuted blocks of eight, stratified by centre) to have all intravascular catheters prepared with 2% chlorhexidine-70% isopropyl alcohol (chlorhexidine-alcohol) or 5% povidone iodine-69% ethanol (povidone iodine-alcohol), with or without scrubbing of the skin with detergent before antiseptic application. Physicians and nurses were not masked to group assignment but microbiologists and outcome assessors were. The primary outcome was the incidence of catheter-related infections with chlorhexidine-alcohol versus povidone iodine-alcohol in the intention-to-treat population. This study is registered with ClinicalTrials.gov, number NCT01629550 and is closed to new participants.

FINDINGS

Between Oct 26, 2012, and Feb 12, 2014, 2546 patients were eligible to participate in the study. We randomly assigned 1181 patients (2547 catheters) to chlorhexidine-alcohol (594 patients with scrubbing, 587 without) and 1168 (2612 catheters) to povidone iodine-alcohol (580 patients with scrubbing, 588 without). Chlorhexidine-alcohol was associated with lower incidence of catheter-related infections (0·28 vs 1·77 per 1000 catheter-days with povidone iodine-alcohol; hazard ratio 0·15, 95% CI 0·05-0·41; p=0·0002). Scrubbing was not associated with a significant difference in catheter colonisation (p=0·3877). No systemic adverse events were reported, but severe skin reactions occurred more frequently in those assigned to chlorhexidine-alcohol (27 [3%] patients vs seven [1%] with povidone iodine-alcohol; p=0·0017) and led to chlorhexidine discontinuation in two patients.

INTERPRETATION

For skin antisepsis, chlorhexidine-alcohol provides greater protection against short-term catheter-related infections than does povidone iodine-alcohol and should be included in all bundles for prevention of intravascular catheter-related infections.

FUNDING

University Hospital of Poitiers, CareFusion.

Multidisciplinary team review of best practices for collection and handling of blood cultures to determine effective interventions for increasing the yield of true-positive bacteremias, reducing contamination, and eliminating false-positive central line-associated bloodstream infections

BACKGROUND

A literature search was conducted using keywords for articles published in English from January 1990 to March 2015. Using criteria related to blood culture collection and handling, the search yielded 101 articles. References used also included Microbiology Laboratory standards, guidelines, and textbook information.

RESULTS

The literature identified diverse and complex issues surrounding blood culture practices, including the impact of false-positive results, laboratory definition of contamination, effect on central line-associated bloodstream infection (CLABSI) reporting, indications for collecting blood cultures, drawing from venipuncture sites versus intravascular catheters, selection of antiseptics, use of needleless connectors, inoculation of blood culture bottles, and optimizing program management in emergency departments, education, and implementation of bundled practice initiatives.

CONCLUSION

Hospitals should optimize best practice in the collection, handling, and management of blood culture specimens, an often overlooked but essential component in providing optimal care of patients in all settings and populations, reducing financial burdens, and increasing the accuracy of reportable CLABSI. Although universal concepts exist in blood culture practices, some issues require further research to determine benefit. Institutions undertaking a review of their blood culture programs are encouraged to use a checklist that addresses elements that encompass the research contained in this review.

Skin preparation with alcohol versus alcohol followed by any antiseptic for preventing bacteraemia or contamination of blood for transfusion

BACKGROUND

Blood for transfusion may become contaminated at any point between collection and transfusion and may result in bacteraemia (the presence of bacteria in the blood), severe illness or even death for the blood recipient. Donor arm skin is one potential source of blood contamination, so it is usual to cleanse the skin with an antiseptic before blood donation. One-step and two-step alcohol based antiseptic regimens are both commonly advocated but there is uncertainty as to which is most effective.

OBJECTIVES

To assess the effects of cleansing the skin of blood donors with alcohol in a one-step compared with alcohol in a two-step procedure to prevent contamination of collected blood or bacteraemia in the recipient.

SEARCH METHODS

In December 2014, for this third update, we searched the Cochrane Wounds Group Specialised Register; The Cochrane Central Register of Controlled Trials (CENTRAL), The Cochrane Library; Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE; and EBSCO CINAHL.

SELECTION CRITERIA

All randomised trials (RCTs) comparing alcohol based donor skin cleansing in a one-step versus a two-step process that includes alcohol and any other antiseptic for pre-venepuncture skin cleansing were considered. Quasi randomised trials were to have been considered in the absence of RCTs.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion.

MAIN RESULTS

No studies (RCTs or quasi RCTs) met the inclusion criteria.

AUTHORS' CONCLUSIONS

We did not identify any eligible studies for inclusion in this review. It is therefore unclear whether a two-step, alcohol followed by antiseptic skin cleansing process prior to blood donation confers any reduction in the risk of blood contamination or bacteraemia in blood recipients, or conversely whether a one-step process increases risk above that associated with a two-step process.

Blood Culture Contamination A Randomized Trial Evaluating the Comparative Effectiveness of 3 Skin Antiseptic Interventions

Objective.

To determine relative rates of blood culture contamination for 3 skin antisepsis interventions—10% povidone iodine aqueous solution (PI), 2% iodine tincture (IT), and 2% Chlorhexidine gluconate in 70% isopropyl alcohol (CHG)—when used by dedicated phlebotomy teams to obtain peripheral blood cultures.

Design.

Randomized crossover trial with hospital floor as the unit of randomization.

Setting.

Teaching hospital with 885 beds.

Patients.

All adult patients undergoing peripheral blood culture collection on 3 medical-surgical floors from May 2009 through September 2009.

Intervention.

Each antisepsis intervention was used for 5 months on each study floor, with random crossover after a 1-month washout period. Phlebotomy teams collected all peripheral blood cultures. Each positive blood culture was adjudicated by physicians blinded to the intervention and scored as a true positive or contaminated blood culture. The primary outcome was the rate of blood culture contamination for each antisepsis agent.

Results.

In total, 12,904 peripheral blood culture sets were evaluated, of which 735 (5.7%) were positive. There were 98 contaminated cultures, representing 13.3% of all positive cultures. The overall blood culture contamination rate for the study population was 0.76%. Intent-to-treat rates of contaminated blood cultures were not significantly different among the 3 antiseptics (P= .18), yielding 0.58% with PI (95% confidence interval [CI], 0.38%-0.86%), 0.76% with IT (95% CI, 0.52%-1.07%), and 0.93% with CHG (95% CI, 0.67%-1.27%).

Conclusion.

Choice of antiseptic agent does not impact contamination rates when blood cultures are obtained by a phlebotomy team and should, therefore, be based on costs or preference.

Trial Registration.

ClinicalTrials.gov identifier: NCT01216761.

Blood Culture Contamination Rates after Skin Antisepsis with Chlorhexidine Gluconate versus Povidone-Iodine in a Pediatric Emergency Department

Objective.

To determine blood culture contamination rates after skin antisepsis with Chlorhexidine, compared with povidone-iodine.

Design.

Retrospective, quasi-experimental study.

Setting.

Emergency department of a tertiary care children's hospital.

Patients.

Children aged 2-36 months with peripheral blood culture results from February 2004 to June 2008. Control patients were children younger than 2 months with peripheral blood culture results.

Methods.

Blood culture contamination rates were compared using segmented regression analysis of time-series data among 3 patient groups: (1) patients aged 2-36 months during the 26-month preintervention period, in which 10% povidone-iodine was used for skin antisepsis before blood culture; (2) patients aged 2-36 months during the 26-month postintervention period, in which 3% Chlorhexidine gluconate was used; and (3) patients younger than 2 months not exposed to the Chlorhexidine intervention (ie, the control group).

Results.

Results from 11,595 eligible blood cultures were reviewed (4,942 from the preintervention group, 4,274 from the postintervention group, and 2,379 from the control group). For children aged 2-36 months, the blood culture contamination rate decreased from 24.81 to 17.19 contaminated cultures per 1,000 cultures (P< .05) after implementation of Chlorhexidine. This decrease of 7.62 contaminated cultures per 1,000 cultures (95% confidence interval, —0.781 to —15.16) represented a 30% relative decrease from the preintervention period and was sustained over the entire postintervention period. No change in contamination rate was observed in the control group (P= .337).

Conclusion.

Skin antisepsis with Chlorhexidine significantly reduces the blood culture contamination rate among young children, as compared with povidone-iodine.

Review of Clinical Trials of Skin Antiseptic Agents Used to Reduce Blood Culture Contamination

False-positive blood culture results may lead to prolonged hospitalization, inappropriate antibiotic administration, and increased healthcare costs. We conducted a review of the literature to assess the effect of skin antiseptic agents on the rate of false-positive blood culture Results. We found no clear evidence to suggest which antiseptic should be used to prevent false-positive Results. Studies suggest, however, a possible benefit from the use of prepackaged skin antiseptic kits and alcohol-containing antiseptics.

Safety guideline: skin antisepsis for central neuraxial blockade

Concise guidelines are presented that recommend the method of choice for skin antisepsis before central neuraxial blockade. The Working Party specifically considered the concentration of antiseptic agent to use and its method of application. The advice presented is based on previously published guidelines, laboratory and clinical studies, case reports, and on the known properties of antiseptic agents.

The Japanese guidelines for the management of sepsis

This is a guideline for the management of sepsis, developed by the Sepsis Registry Committee of The Japanese Society of Intensive Care Medicine (JSICM) launched in March 2007. This guideline was developed on the basis of evidence-based medicine and focuses on unique treatments in Japan that have not been included in the Surviving Sepsis Campaign guidelines (SSCG), as well as treatments that are viewed differently in Japan and in Western countries. Although the methods in this guideline conform to the 2008 SSCG, the Japanese literature and the results of the Sepsis Registry Survey, which was performed twice by the Sepsis Registry Committee in intensive care units (ICUs) registered with JSICM, are also referred. This is the first and original guideline for sepsis in Japan and is expected to be properly used in daily clinical practice.

This article is translated from Japanese, originally published as “The Japanese Guidelines for the Management of Sepsis” in the Journal of the Japanese Society of Intensive Care Medicine (J Jpn Soc Intensive Care Med), 2013; 20:124–73. The original work is at http://dx.doi.org/10.3918/jsicm.20.124.

A prospective randomised trial to compare the efficacy of povidone-iodine 10% and chlorhexidine 2% for skin disinfection

Context:

Infectious complications of invasive procedures affect patient outcomes adversely. Choice of antiseptic solution at the time of insertion is one of the major factors affecting their incidence.

Aims:

This study was undertaken to compare efficacy of chlorhexidine 2% and povidone iodine 10% for skin disinfection prior to placement of epidural and central venous catheters (CVCs).

Settings and Design:

A prospective randomised trial in the operating rooms of a tertiary referral cancer centre.

Methods:

Sixty consecutive adult patients undergoing elective oncosurgery requiring placement of epidural and CVCs were enrolled. Paired skin swabs were collected before and after application of the antiseptic solution. The samples were incubated in McConkey's media and blood agar at 35°C for up to 24 h. Any bacterial growth was graded as: <10 colonies - poor growth, 10-50 colonies - moderate growth and >50 colonies as heavy growth. Data on demographics and antibiotic prophylaxis and costs was collected for all patients.

Statistical Analysis:

Student's t-test and Mann-Whitney tests were used to analyse data, P<0.05 was considered significant.

Results:

Demographics and antibiotic prophylaxis use was similar in both groups. Before application of antiseptic solution, a variety of micro-organisms were grown from most patients with growth ranging from none-heavy. No organism was grown after application of either antiseptic solution from any patient.

Conclusions:

We found no differences between 2% chlorhexidine and 10% povidone-iodine for skin disinfection in regard to costs, efficacy or side-effects.

Identifying and classifying bloodstream infections among hemodialysis patients

Bloodstream infections (BSIs) are a prominent clinical problem in patients undergoing hemodialysis. These infections appear to be more common among patients who have a central line as their dialysis access and can be associated with substantial morbidity and mortality. Accurately diagnosing BSIs clearly influences patient management, but is also an important part of an infection prevention program; particularly as facility BSI rates are becoming a recognized quality measure for which dialysis facilities might be held accountable. Blood cultures remain the gold standard for diagnosing BSIs and a number of practices can affect the sensitivity and specificity of this important laboratory test. Optimizing the collection of blood cultures can assist providers with interpretation of positive blood cultures and can help minimize the impact of false-positive and false-negative cultures. This review will describe differences between BSI definitions, examine the use of blood cultures to identify these infections including the use of recommended best practices to maximize culture yield, and highlight characteristics that can assist in the clinical interpretation of positive blood cultures.

Update on blood cultures: how to obtain, process, report, and interpret

The detection and identification of microorganisms circulating in the bloodstream of patients is arguably one of the most important functions of the clinical microbiology laboratory. Effective implementation of this function requires careful consideration of specimen collection and processing, culture techniques, result reporting, and, perhaps most importantly, result interpretation by the physician. The purpose of this review is to provide a synopsis of the current state of the art for each of these areas, with the intention of providing adequate information to enable clinical laboratory personnel and physicians to critically evaluate and, if required, improve their current blood culture practices.

Skin preparation with alcohol versus alcohol followed by any antiseptic for preventing bacteraemia or contamination of blood for transfusion

BACKGROUND

Blood for transfusion may become contaminated at any point between collection and transfusion and may result in bacteraemia (the presence of bacteria in the blood), severe illness or even death for the blood recipient. Donor arm skin is one potential source of blood contamination, so it is usual to cleanse the skin with an antiseptic before blood donation. One-step and two-step alcohol based antiseptic regimens are both commonly advocated but there is uncertainty as to which is most effective.

OBJECTIVES

To assess the effects of cleansing the skin of blood donors with alcohol in a one-step compared with alcohol in a two-step procedure to prevent contamination of collected blood or bacteraemia in the recipient.

SEARCH METHODS

For this second update we searched the Cochrane Wounds Group Specialised Register (searched 20 November 2012); The Cochrane Central Register of Controlled Trials (CENTRAL) The Cochrane Library 2012, Issue 11; Ovid MEDLINE (20011 to November Week 2 2012); Ovid MEDLINE (In-Process & Other Non-Indexed Citations November 20, 2012); Ovid EMBASE ( 20011 to 2012 Week 46); and EBSCO CINAHL ( 2008 to 15 November 2012).

SELECTION CRITERIA

All randomised trials (RCTs) comparing alcohol based donor skin cleansing in a one-step versus a two-step process that includes alcohol and any other antiseptic for pre-venepuncture skin cleansing were considered. Quasi randomised trials were to have been considered in the absence of RCTs.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion.

MAIN RESULTS

No studies (RCTs or quasi RCTs) met the inclusion criteria.

AUTHORS' CONCLUSIONS

We did not identify any eligible studies for inclusion in this review. It is therefore unclear whether a two-step, alcohol followed by antiseptic skin cleansing process prior to blood donation confers any reduction in the risk of blood contamination or bacteraemia in blood recipients, or conversely whether a one-step process increases risk above that associated with a two-step process.

Reducing blood culture contamination in the emergency department: an interrupted time series quality improvement study

OBJECTIVES

Blood culture contamination is a common problem in the emergency department (ED) that leads to unnecessary patient morbidity and health care costs. The study objective was to develop and evaluate the effectiveness of a quality improvement (QI) intervention for reducing blood culture contamination in an ED.

METHODS

The authors developed a QI intervention to reduce blood culture contamination in the ED and then evaluated its effectiveness in a prospective interrupted times series study. The QI intervention involved changing the technique of blood culture specimen collection from the traditional clean procedure to a new sterile procedure, with standardized use of sterile gloves and a new materials kit containing a 2% chlorhexidine skin antisepsis device, a sterile fenestrated drape, a sterile needle, and a procedural checklist. The intervention was implemented in a university-affiliated ED and its effect on blood culture contamination evaluated by comparing the biweekly percentages of blood cultures contaminated during a 48-week baseline period (clean technique) and 48-week intervention period (sterile technique), using segmented regression analysis with adjustment for secular trends and first-order autocorrelation. The goal was to achieve and maintain a contamination rate below 3%.

RESULTS

During the baseline period, 321 of 7,389 (4.3%) cultures were contaminated, compared to 111 of 6,590 (1.7%) during the intervention period (p < 0.001). In the segmented regression model, the intervention was associated with an immediate 2.9% (95% confidence interval [CI] = 2.2% to 3.2%) absolute reduction in contamination. The contamination rate was maintained below 3% during each biweekly interval throughout the intervention period.

CONCLUSIONS

A QI assessment of ED blood culture contamination led to development of a targeted intervention to convert the process of blood culture collection from a clean to a fully sterile procedure. Implementation of this intervention led to an immediate and sustained reduction of contamination in an ED with a high baseline contamination rate.

Current approaches to the diagnosis of bacterial and fungal bloodstream infections in the intensive care unit

Healthcare systems spend considerable resources collecting and processing blood cultures for the detection of blood stream pathogens. The process is initiated with the collection of blood cultures that depend upon proper skin disinfection, collection of an adequate number of specimens and volume of blood, and prompt processing in a sensitive culture system. Complementing blood cultures and gaining in use are techniques such as nucleic acid amplification tests and mass spectroscopy that allow clinical laboratories to detect and identify organisms from blood cultures substantially faster than conventional systems. Furthermore, certain resistance mutations can be detected within hours of organism detection, thus providing valuable guidance to clinicians who strive to initiate the appropriate antimicrobial therapy as rapidly as possible, and who wish to discontinue unnecessary drugs expeditiously. Molecular and mass spectroscopy techniques are changing sepsis diagnosis rapidly and will provide far more specific information far more quickly, but the performance characteristics of these systems must be understood by intensivists who use such information to guide their patient management.

In vitro antiseptic effects on viability of neuronal and Schwann cells

BACKGROUND AND OBJECTIVE

Chlorhexidine is recommended by several anesthesiology societies for antisepsis before regional anesthesia, but there is concern it may be neurotoxic. We evaluated the cytotoxicity of chlorhexidine and povidone-iodine in human neuronal and rat Schwann cells.

METHODS

Human SH-SY5Y neuroblastoma and rat RSC96 Schwann cells were incubated with serial dilutions of 2% chlorhexidine gluconate and 10% povidone-iodine for 10 minutes, and viability was assessed with the MTT colorimetry assay and a fluorescent assay using calcein and ethidium. Cell morphology during antiseptic incubation was observed under light microscopy. To estimate the amount of antiseptic a needle carries through tissues, tritium radioactivity was measured in an animal injection model.

RESULTS

Chlorhexidine at all tested concentrations significantly decreased viability compared with controls in both SH-SY5Y and RSC96 cells (P < 0.001). Povidone-iodine significantly decreased viability for both cells at concentrations of 0.2% or higher (P < 0.001). At the same dilutions of 1:200, 1:150, and 1:100, chlorhexidine was more cytotoxic than povidone-iodine for both cells (P< 0.001). During chlorhexidine treatment, both cell types became rounded and shriveled. Less dramatic changes were observed with povidone-iodine. In the injection model, 1.75% ± 1.29% of the maximum amount of radioactive contamination was carried through tissues.

CONCLUSIONS

Chlorhexidine gluconate and povidone-iodine were cytotoxic to SH-SY5Y (neuronal) and RSC96 (Schwann) cells. Chlorhexidine was more potent than povidone-iodine at more dilute concentrations. However, the toxicity of the two was not different at concentrations used clinically. When using either of these agents for antisepsis before regional anesthesia, it is prudent to allow adequate drying time after application.

The forgotten role of alcohol: a systematic review and meta-analysis of the clinical efficacy and perceived role of chlorhexidine in skin antisepsis

Background

Skin antisepsis is a simple and effective measure to prevent infections. The efficacy of chlorhexidine is actively discussed in the literature on skin antisepsis. However, study outcomes due to chlorhexidine-alcohol combinations are often attributed to chlorhexidine alone. Thus, we sought to review the efficacy of chlorhexidine for skin antisepsis and the extent of a possible misinterpretation of evidence.

Methods

We performed a systematic literature review of clinical trials and systematic reviews investigating chlorhexidine compounds for blood culture collection, vascular catheter insertion and surgical skin preparation. We searched PubMed, CINAHL, the Cochrane Library, the Agency for Healthcare Research and Quality website, several clinical trials registries and a manufacturer website. We extracted data on study design, antiseptic composition, and the following outcomes: blood culture contamination, catheter colonisation, catheter-related bloodstream infection and surgical site infection. We conducted meta-analyses of the clinical efficacy of chlorhexidine compounds and reviewed the appropriateness of the authors′ attribution.

Results

In all three application areas and for all outcomes, we found good evidence favouring chlorhexidine-alcohol over aqueous competitors, but not over competitors combined with alcohols. For blood cultures and surgery, we found no evidence supporting chlorhexidine alone. For catheters, we found evidence in support of chlorhexidine alone for preventing catheter colonisation, but not for preventing bloodstream infection. A range of 29 to 43% of articles attributed outcomes solely to chlorhexidine when the combination with alcohol was in fact used. Articles with ambiguous attribution were common (8–35%). Unsubstantiated recommendations for chlorhexidine alone instead of chlorhexidine-alcohol were identified in several practice recommendations and evidence-based guidelines.

Conclusions

Perceived efficacy of chlorhexidine is often in fact based on evidence for the efficacy of the chlorhexidine-alcohol combination. The role of alcohol has frequently been overlooked in evidence assessments. This has broader implications for knowledge translation as well as potential implications for patient safety.

An ex vivo bacteriologic study comparing antiseptic techniques for natural orifice translumenal endoscopic surgery (NOTES) via the gastrointestinal tract

BACKGROUND

NOTES via the gastrointestinal tract raises the specter of intra-peritoneal infection. Various anti-microbial techniques have been employed in animal and human survival studies, including saline lavage, intravenous and topical antibiotics, and povidone-iodine, although there is a paucity of data regarding their general effectiveness.

AIM

To assess the effectiveness of existing sterilization techniques for NOTES by quantifying and speciating colony-forming units (CFUs) before and after treatment.

DESIGN

Ex vivo animal studies; bacteriological study.

METHODS

Stomachs and distal colons were harvested en bloc from ten fasted adult white pigs following euthanasia. Half received cefazolin 1 g intravenously prior to killing. Multiple tissue samples were obtained from each resected organ. Each tissue sample was then assigned to one of five treatment arms: (1) normal saline, (2) Betadine, (3) cefazolin/metronidazole suspension, (4) chlorhexidine, (5) no treatment. Fifteen samples were used per arm. After treatment, the mucosal surface of each sample was swabbed and inoculated in normal saline, followed by serial dilutions, which were then plated onto sheep's blood agar plates and incubated under aerobic and anaerobic conditions. CFUs were quantified and speciated.

RESULTS

Median bacterial density was estimated to be 8.0 × 10(5) CFUs/ml (stomach) and 1.9 × 10(6) CFUs/ml (colon). The predominant organisms were Escherichia coli (stomach) and both E. coli and Enterococcus sp. (colon). Saline and antibiotic suspension lavages caused a 1-log reduction in stomach and colon. Betadine/chlorhexidine lavage resulted in a 4-log reduction. Intravenous antibiotics alone resulted in a 4-log reduction. Combining intravenous antibiotics and either Betadine or chlorhexidine decreased counts to the 10(1) level. By Kruskal-Wallis method, differences were statistically significant (p = 0.001).

CONCLUSIONS

The use of intravenous antibiotics in addition to topical Betadine or chlorhexidine effectively reduced microbial burden in both gastric and colonic mucosa in this porcine model to the 10(1) level.

Factors affecting microbial contamination rate of cord blood collected for transplantation

BACKGROUND

Collection and processing of cord blood (CB) is associated with significant risk of microbial contamination and hence relevant standards mandate microbial screening of the final product. This study aimed to determine the contamination rate and associated risk factors during 14 years of banking at the Sydney Cord Blood Bank.

STUDY DESIGN AND METHODS

CB was collected and processed using a closed system and tested for contamination using blood culture bottles (BacT/ALERT, bioMérieux) incubated for a minimum of 5 days. Four microbial screening methods were used with different combinations of inoculated bottles (adult or pediatric) and associated sample volumes (10 or 1 mL).

RESULTS

Of 13,344 CB units screened, 537 (4.0%) tested positive for contamination, with Bacteroides spp. (20.9%), Staphylococcus spp. (18.6%), and Propionibacterium spp. (13.7%) being the most common isolates. The contamination rate reduced from 10% in 1997 to 1.1% in 2009. Multivariate analysis demonstrated the following variables were independently associated with higher contamination rates: vaginal delivery, collection by obstetric staff, and use of an anaerobic bottle in addition to an aerobic bottle (which facilitated a larger sample inoculation volume than pediatric bottles).

CONCLUSIONS

This study demonstrates that contamination rates of CB collected for transplantation can be substantially reduced by collection after cesarean delivery and utilizing trained CB collection staff. These data also indicate that the common practice of testing using a pediatric (aerobic) bottle with its attendant small volume of the final CB product may be suboptimal for sensitive detection of contaminating anaerobic microbes.

A review of topical therapy for skin infections with bacteria and yeast

BACKGROUND

Cutaneous infections with bacteria and yeasts are common in small animal practice. Treatment with systemic antibiotics or antifungal agents may not be ideal, because of the increasing development of multiresistant organisms, the cost and the possible adverse effects. Topical antimicrobials may be used as adjunctive therapy to systemic treatment or as sole therapy instead of systemic treatment.

OBJECTIVE

This literature review evaluated studies on topical antimicrobial treatment of skin infections.

METHODS

In vitro and in vivo studies evaluating topical antimicrobial agents were identified using a number of electronic and manual searches of textbooks and articles. Studies were evaluated, and the evidence for or against the use of the topical agents was extracted.

RESULTS

There is good evidence for the efficacy of chlorhexidine and, to a lesser degree, benzoyl peroxide in canine bacterial skin infections. There is limited evidence for the efficacy of silver sulfadiazine and medical honey against bacterial skin infections in the dog, and for the efficacy of hydrogen peroxide and stannous fluoride in the horse. Good evidence supports the use of a combination of chlorhexidine and miconazole in dogs with cutaneous Malassezia infections. There is insufficient evidence to recommend any other topical therapy for use in cutaneous infections.

CONCLUSIONS AND CLINICAL IMPORTANCE

Although many antimicrobial topicals are marketed in veterinary dermatology, the efficacy has been reported for only a minority of agents. Randomized controlled trials evaluating various topical treatments are therefore urgently needed.

Would earlier microbe identification alter antibiotic therapy in bacteremic emergency department patients?

BACKGROUND

Although debate exists about the treatment of sepsis, few disagree about the benefits of early, appropriately targeted antibiotic administration.

STUDY OBJECTIVES

To determine the appropriateness of empiric antimicrobial therapy and the extent to which therapy would be altered if the causative organism for sepsis was known at the time of administration.

METHODS

This was a retrospective cohort study, conducted in an academic Emergency Department (ED), on consecutive positive blood cultures between November 1, 2008 and February 1, 2009. Blood cultures and the appropriateness of administered antimicrobial therapy were evaluated. Therapy choices were categorized based on whether or not a physician, complying with antimicrobial guidelines, would have made changes to empiric antibiotic therapy had the causative organism initially been known.

RESULTS

There were 90 positive blood cultures obtained from 84 patients. Of these, 21.1% (n=19) were considered contaminants. The final categorization of empiric antibiotics given in the ED for the remaining blood culture results were: 1) therapy would be changed to narrower-spectrum antibiotics (n=34, 55.7%); 2) therapy would be changed because the organism was not covered (n=13, 21.3%); and 3) therapy would remain the same (n=14, 23.0%). There was 90.2% inter-rater agreement for these classifications (p<0.0001), with a kappa of 0.84. Polymerase chain reaction analysis had a statistically significant advantage (p<0.0001) over Infectious Disease Society of America protocols in facilitating accurate antimicrobial therapies.

CONCLUSION

This study confirms the need for more rapid and accurate laboratory methods for bloodstream pathogen identification.