Antimicrobial Tolerance in Cross-Kingdom Dual-Species Biofilms Formed by Fungi and Bacteria

Candida albicans, the most common pathogenic fungus, can form biofilms on the surface of medical devices and often causes bloodstream infections. Biofilms have a complex structure composed of microorganisms and a surrounding extracellular matrix. Biofilms are difficult to treat because they are resistant to antifungal drugs and the host environment. Nearly one in four patients with candidemia have a polymicrobial infection. These polymicrobial biofilms, especially those comprising cross-kingdom species of fungi and bacteria, can lead to long hospital stays and high mortality rates. This review outlines the unique interactions of dual-species biofilms with Candida albicans and the clinically important bacteria Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli.

Healthcare-Associated Bloodstream Infections Due to Multidrug-Resistant Acinetobacter baumannii in COVID-19 Intensive Care Unit: A Single-Center Retrospective Study

Healthcare-associated infections are an emerging cause of morbidity and mortality in COVID-19 intensive care units (ICUs) worldwide, especially those caused by multidrug-resistant (MDR) pathogens. The objectives of this study were to assess the incidence of bloodstream infections (BSIs) among critically ill COVID-19 patients and to analyze the characteristics of healthcare-associated BSIs due to MDR Acinetobacter baumannii in an COVID-19 ICU. A single-center retrospective study was conducted at a tertiary hospital during a 5-month period. The detection of carbapenemase genes was performed by PCR and genetic relatedness by pulsed-field gel electrophoresis (PFGE) and multilocus-sequence typing. A total of 193 episodes were registered in 176 COVID-19 ICU patients, with an incidence of 25/1000 patient-days at risk. A. baumannii was the most common etiological agent (40.3%), with a resistance to carbapenems of 100%. The blaOXA-23 gene was detected in ST2 isolates while the blaOXA-24 was ST636-specific. PFGE revealed a homogeneous genetic background of the isolates. The clonal spread of OXA-23-positive A. baumannii is responsible for the high prevalence of MDR A. baumannii BSIs in our COVID-19 ICU. Further surveillance of resistance trends and mechanisms is needed along with changes in behavior to improve the implementation of infection control and the rational use of antibiotics.

Candida albicans Promotes the Antimicrobial Tolerance of Escherichia coli in a Cross-Kingdom Dual-Species Biofilm

Cross-kingdom multi-species biofilms consisting of fungi and bacteria are often resistant to antimicrobial treatment, leading to persistent infections. We evaluated whether the presence of Candida albicans affects the antibacterial tolerance of Escherichia coli in dual-species biofilms and explored the underlying mechanism. We found that the survival of E. coli in the presence of antibacterial drugs was higher in dual-species biofilms compared to single-species biofilms. This tolerance-inducing effect was observed in E. coli biofilms that were treated with a C. albicans culture supernatant. To explore the antibacterial tolerance-inducing factor contained in the culture supernatant and identify the tolerance mechanism, a heated supernatant, a supernatant treated with lyticase, DNase, and proteinase K, or a supernatant added to a drug efflux pump inhibitor were used. However, the tolerance-inducing activity was not lost, indicating the existence of some other mechanisms. Ultrafiltration revealed that the material responsible for tolerance-inducing activity was <10 kDa in size. This factor has not yet been identified and needs further studies to understand the mechanisms of action of this small molecule precisely. Nevertheless, we provide experimental evidence that Candida culture supernatant induces E. coli antibacterial tolerance in biofilms. These findings will guide the development of new treatments for dual-species biofilm infections.

Convergence of Biofilm Formation and Antibiotic Resistance in Acinetobacter baumannii Infection

Acinetobacter baumannii (A. baumannii) is a leading cause of nosocomial infections as this pathogen has certain attributes that facilitate the subversion of natural defenses of the human body. A. baumannii acquires antibiotic resistance determinants easily and can thrive on both biotic and abiotic surfaces. Different resistance mechanisms or determinants, both transmissible and non-transmissible, have aided in this victory over antibiotics. In addition, the propensity to form biofilms (communities of organism attached to a surface) allows the organism to persist in hospitals on various medical surfaces (cardiac valves, artificial joints, catheters, endotracheal tubes, and ventilators) and also evade antibiotics simply by shielding the bacteria and increasing its ability to acquire foreign genetic material through lateral gene transfer. The biofilm formation rate in A. baumannii is higher than in other species. Recent research has shown how A. baumannii biofilm-forming capacity exerts its effect on resistance phenotypes, development of resistome, and dissemination of resistance genes within biofilms by conjugation or transformation, thereby making biofilm a hotspot for genetic exchange. Various genes control the formation of A. baumannii biofilms and a beneficial relationship between biofilm formation and "antimicrobial resistance" (AMR) exists in the organism. This review discusses these various attributes of the organism that act independently or synergistically to cause hospital infections. Evolution of AMR in A. baumannii, resistance mechanisms including both transmissible (hydrolyzing enzymes) and non-transmissible (efflux pumps and chromosomal mutations) are presented. Intrinsic factors [biofilm-associated protein, outer membrane protein A, chaperon-usher pilus, iron uptake mechanism, poly-β-(1, 6)-N-acetyl glucosamine, BfmS/BfmR two-component system, PER-1, quorum sensing] involved in biofilm production, extrinsic factors (surface property, growth temperature, growth medium) associated with the process, the impact of biofilms on high antimicrobial tolerance and regulation of the process, gene transfer within the biofilm, are elaborated. The infections associated with colonization of A. baumannii on medical devices are discussed. Each important device-related infection is dealt with and both adult and pediatric studies are separately mentioned. Furthermore, the strategies of preventing A. baumannii biofilms with antibiotic combinations, quorum sensing quenchers, natural products, efflux pump inhibitors, antimicrobial peptides, nanoparticles, and phage therapy are enumerated.

Ten-Year Changes in Bloodstream Infection With Acinetobacter Baumannii Complex in Intensive Care Units in Eastern China: A Retrospective Cohort Study

Background: There is little evidence on the changing prevalence, microbiological profile, and outcome of nosocomial Acinetobacter baumannii complex (ABC)-caused bloodstream infection (ABCBSI) specified in intensive care units (ICUs) in long-term studies, especially in China. Objective: We aimed to investigate changes in incidence, antibiotic resistance, therapy, and prognosis of ABCBSI in ICUs in eastern China during 2009-2018. Methods: A multicenter retrospective cohort study was conducted, and microbiological and clinical data for patients with ABCBSI acquired in nine adult ICUs in eastern China from 2009 to 2018. Results: A total of 202 cases were enrolled. For the years 2009-2010, 2011-2012, 2013-2014, 2015-2016, and 2017-2018, the incidence of ABCBSI increased significantly, as did the percentage of pan-drug-resistant isolates and resistant rates to most of antimicrobial agents; the percentage of drug-sensitive isolates decreased (all P < 0.05). The frequency of treatment with carbapenems and tigecycline increased, and that of cephalosporins decreased. Compared with those in the first years (2009-2012), ABCBSI patients in the lattermost years (2017-2018) were less often treated with appropriate empirical therapy, more often underwent pneumonia-related ABCBSI and mechanical ventilation support, and had higher 28-day mortality rates. Multivariate Cox regression indicated that increase in the degree of ABC antibiotics resistance, pneumonia-related ABCBSI, and septic shock were risk factors of 28-day mortality and associated with significant lower survival days. Conclusions: The past decade has witnessed a marked increase in the incidence of ABCBSI and in antibiotic resistance, with increasing pneumonia-related infections and worrisome mortality in ICUs in China. Controlling increasing resistance and preventing nosocomial pneumonia may play important roles in combatting these infections.

Identification of microorganisms directly from blood culture bottles with polymicrobial growth: comparison of FilmArray and direct MALDI-TOF MS

Bloodstream infections (BSIs) are related to high mortality and morbidity. Rapid administration of effective antimicrobial treatment is crucial for patient survival. Recently developed rapid methods to identify pathogens directly from blood culture bottles speed up diagnosis of BSIs. The present study compares the performance of two rapid identification methods, FilmArray and direct MALDI-TOF MS, on identifying microorganisms directly from positive blood culture bottles with polymicrobial growth. FilmArray and direct MALDI-TOF MS were performed directly on positive clinical and simulated polymicrobial blood culture bottles. Assay results were compared with standard culture methods. In total, 110 polymicrobial blood culture samples, of which 96 samples contained two microorganisms while 14 samples contained three microorganisms, were studied. FilmArray was able to identify 215/234 (92.0%) of isolates detected by the standard culture method and successfully identified all microorganisms in 88/110 (80.0%) of blood culture bottles. In contrast, direct MALDI-TOF MS was only able to identify 65/234 (27.8%) of isolates and managed to identify all microoganisms in 2/110 (2.1%) of blood culture bottles. FilmArray is a rapid method for direct identification of polymicrobial blood culture samples that can complement the conventional identification methods. Direct MALDI-TOF MS has low performance with polymicrobial samples.

Pediatric Ambulatory Central Line-Associated Bloodstream Infections

BACKGROUND

Inpatient pediatric central line-associated bloodstream infections (CLABSIs) cause morbidity and increased health care use. Minimal information exists for ambulatory CLABSIs despite ambulatory central line (CL) use in children. In this study, we identified ambulatory pediatric CLABSI incidence density, risk factors, and outcomes.

METHODS

Retrospective cohort with nested case-control study at 5 sites from 2010 through 2015. Electronic queries were used to identify potential cases on the basis of administrative and laboratory data. Chart review was used to confirm ambulatory CL use and adjudicated CLABSIs. Bivariate followed by multivariable backward logistic regression was used to identify ambulatory CLABSI risk factors.

RESULTS

Queries identified 4600 potentially at-risk children; 1658 (36%) had ambulatory CLs. In total, 247 (15%) patients experienced 466 ambulatory CLABSIs with an incidence density of 0.97 CLABSIs per 1000 CL days. Incidence density was highest among patients with tunneled externalized catheters versus peripherally inserted central catheters and totally implanted devices: 2.58 CLABSIs per 1000 CL days versus 1.46 vs 0.23, respectively (P < .001). In a multivariable model, clinic visit (odds ratio [OR] 2.8; 95% confidence interval [CI]: 1.4-5.5) and low albumin (OR 2.3; 95% CI: 1.2-4.3) were positively associated with CLABSI, and prophylactic antimicrobial agents for underlying conditions within the preceding 30 days (OR 0.22; 95% CI: 0.12-0.40) and operating room CL placement (OR 0.36; 95% CI: 0.16-0.79) were inversely associated with CLABSI. A total of 396 patients (85%) were hospitalized because of ambulatory CLABSI with an 8-day median length of stay (interquartile range 5-13).

CONCLUSIONS

Ambulatory pediatric CLABSI incidence density is appreciable and associated with health care use. CL type, patients with low albumin, prophylactic antimicrobial agents, and placement setting may be targets for reduction efforts.

Development of a Clinical Prediction Model for Central Line-Associated Bloodstream Infection in Children Presenting to the Emergency Department

OBJECTIVE

The majority of the children with a central line who present to the emergency department with fever or other signs of bacteremia do not have a central line-associated bloodstream infection (CLABSI). Our objective was to develop a clinical prediction model for CLABSI among this group of children in order to ultimately limit unnecessary hospital admissions and antibiotic use.

METHODS

We performed a nested case-control study of children with a central line who presented to the emergency department of an urban, tertiary care children's hospital between January 2010 and March 2015 and were evaluated for CLABSI with a blood culture.

RESULTS

The final multivariable model developed to predict CLABSI consisted of 12 factors: age younger than 5 years, black race, use of total parenteral nutrition, tunneled central venous catheter, double-lumen catheter, absence of other bacterial infection, absence of viral upper respiratory tract infection symptoms, diarrhea, emergency department temperature greater than 39.5°C, fever prior to presentation, neutropenia, and spring/summer season. The clinical prediction score had good discrimination for CLABSI with a c-statistic of 0.81 (confidence interval, 0.77-0.85). A cut point less than 6 was associated with a sensitivity of 98.5% and a negative predictive value of 99.2% for CLABSI.

CONCLUSIONS

We were able to identify risk factors and develop a clinical prediction model for CLABSI in children presenting to the emergency department. Once validated in future study, this clinical prediction model could be used to assess the need for hospitalization and/or antibiotics among this group of patients.

Synergistic antimicrobial combination of carvacrol and thymol impairs single and mixed-species biofilms of Candida albicans and Staphylococcus epidermidis

Candida albicans and Staphylococcus epidermidis are important opportunistic human pathogens, which form mixed-species biofilms and cause recalcitrant device associated infections in clinical settings. Further to many reports suggesting the therapeutic potential of plant-derived monoterpenoids, this study investigated the interaction of the monoterpenoids carvacrol (C) and thymol (T) against mono- and mixed-species growth of C. albicans and S. epidermidis. C and T exhibited synergistic antimicrobial activity. The time-kill study and post-antimicrobial effect results revealed the effective microbicidal action of the C + T combination. Filamentation, surface coating assays and live-dead staining of biofilms determined the anti-hyphal, antiadhesion, and anti-biofilm activities of the C + T combination, respectively. Notably, this combination killed highly tolerant persister cells of mono-species and mixed-species biofilms and demonstrated less risk of resistance development. The collective data suggest that the C + T combination could act as an effective therapeutic agent against biofilm associated mono-species and mixed-species infections of C. albicans and S. epidermidis.

Standardize, Engage, and Collaborate: An Initiative to Reduce Community Acquired Central Line Blood Stream Infections Across the Continuum of Care

BACKGROUND

Community acquired blood stream infections (CA-CLABSI) are a major source of morbidity and mortality for pediatric patients. Many organizations discharge pediatric patients to home health agencies to care for central lines. To reduce the incidence of CA-CLABSIs requires a concentrated effort between hospitals and home health agencies. It is important for home health agencies to be accountable for the care and maintenance they provide to patients with central lines. Local Problem: At a large children's hospital, CA-CLABSI metrics and collaboration with home health agencies to reduce CACLABSI events lacked organizational standardization.

METHODS

An organizational committee was formed to establish standards of care for CA-CLABSI follow-up and reduction.

RESULTS

As a result of the committee's work, several best practices resulted including the creation of a CA-CLABSI resource booklet; a screening tool to identify contributing risks associated with a CA-CLABSI, and increased awareness of CA-CLABSIs. Since implementation of these best practices, the organization has seen a 30% reduction in the number of CA-CLABSIs. Standardization of CA-CLABSI efforts and proactive surveillance of central line care may lead to decreases in the number of CA-CLABSI events. Collaboration between service lines may identify siloed best practices that can be implemented organizationally that may have a large impact.

Clinical predictors and outcome impact of community-onset polymicrobial bloodstream infection

OBJECTIVES

Very few studies have characterised community-onset polymicrobial bloodstream infections (BSIs). This study determined the incidence, risk factors, and outcomes of polymicrobial BSI as compared with monomicrobial BSI in a cohort of patients with community-onset BSIs.

METHODS

This prospective cohort study enrolled consecutive patients with laboratory confirmed BSIs who were admitted to two tertiary emergency departments in Taiwan between 1 January 2015 and 31 December 2016. It assessed the independent impact of polymicrobial BSIs on survival by a propensity score weighting method. Subsequently, independent clinical predictors were identified with multivariate logistic regression model analysis with internal validation by 10-fold cross validation.

RESULTS

Among 1166 patients with community-onset BSI, 133 (10.9%) episodes of polymicrobial BSIs occurred. Anaerobe, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus spp., and Candida spp. were the most common isolated microorganisms in polymicrobial BSI. Polymicrobial BSIs were associated with an increased 90-day mortality rate (OR 2.20, 95% CI 1.98-2.60). A prediction model was built to predict polymicrobial BSI with moderate predictability (c statistic = 0.78). Significant predictors included biliary tract infection, nosocomial infection, nursing home residence, stroke, and afebrile presentation.

CONCLUSIONS

Polymicrobial BSI occurred in approximately 1 in 10 episodes of community-onset BSI and was independently associated with excess mortality. Clinical predictors identified in this study may help guide the prescription of empiric broad-spectrum antibiotics.

A 'culture' shift: Application of molecular techniques for diagnosing polymicrobial infections

With the advancement of microbiological discovery, it is evident that many infections, particularly bloodstream infections, are polymicrobial in nature. Consequently, new challenges have emerged in identifying the numerous etiologic organisms in an accurate and timely manner using the current diagnostic standard. Various molecular diagnostic methods have been utilized as an effort to provide a fast and reliable identification in lieu or parallel to the conventional culture-based methods. These technologies are mostly based on nucleic acid, proteins, or physical properties of the pathogens with differing advantages and limitations. This review evaluates the different molecular methods and technologies currently available to diagnose polymicrobial infections, which will help determine the most appropriate option for future diagnosis.

Comparing catheter-related bloodstream infections in pediatric and adult cancer patients

OBJECTIVE

Central venous catheters (CVCs) are essential to treatment of children with cancer. There are no studies comparing catheter-related bloodstream infections (CRBSIs) in pediatric cancer patients to those in adults, although current guidelines for management of CRBSI do not give separate guidelines for the pediatric population. In this study, we compared CRBSIs in both the pediatric and adult cancer population.

METHODS

We retrospectively reviewed the electronic medical records of 92 pediatric and 156 adult patients with CRBSI cared for at MD Anderson Cancer Center between September 2005 and March 2014.

RESULTS

We evaluated 248 patients with CRBSI. There was a significant difference in etiology of CRBSI between pediatric and adult patients (P = 0.002), with the former having less Gram-negative organisms (27 vs. 46%) and more polymicrobial infections (10 vs. 1%, P = 0.003). Pediatric patients had less hematologic malignancies (58 vs. 74%) and less neutropenia at presentation (40 vs. 54%) when compared with adult patients. Peripheral blood cultures were available in only 43% of pediatric cases. CVC was removed in 64% of pediatric cases versus 88% of adult cases (P < 0.0001).

CONCLUSION

We found higher rates of Gram-negative organisms in adults and higher rates of polymicrobial in children. Because of the low rates of peripheral blood cultures and the low rates of CVC removal, CRBSI diagnosis could be challenging in pediatrics. A modified CRBSI definition relying more on clinical criteria may be warranted.

Health care institutional charges associated with ambulatory bloodstream infections in pediatric oncology and stem cell transplant patients

BACKGROUND

The impact of ambulatory bloodstream infections (Amb-BSIs) in pediatric oncology and stem cell transplant (PO/SCT) patients is poorly understood, although a large portion of their treatment increasingly occurs in this setting. This study aimed to understand the economic impact and length of stay (LOS) associated with these infections.

PROCEDURE

Charges and LOS were retrospectively collected and analyzed for Amb-BSI events leading to a hospital admission between 2012 and 2013 in a tertiary, university-affiliated hospital. Events were grouped as BSI-MIXED when hospitalizations with care unrelated to the infection-extended LOS by more than 24 hr or as BSI-PURE for all others. Billing codes were used to group charges and main drivers were analyzed.

RESULTS

Seventy-four BSI events were identified in 61 patients. Sixty-nine percent met definition for central line-associated BSI (CLABSI). Median total charge and LOS for an Amb-BSI were $40,852 (interquartile range [IQR] $44,091) and 7 days (IQR 6), respectively. Median charges for BSI-PURE group (N = 62) were $36,611 (IQR $34,785) and $89,935 (IQR $153,263) in the BSI-MIXED (N = 12) group. Median LOS was 6 (IQR 5) days in the BSI-PURE group and 15 (IQR 24) in the BSI-MIXED. Room, pharmacy, and procedure charges accounted for more than 70% of total charges in all groups.

CONCLUSIONS

Amb-BSIs in PO/SCT patients result in significant healthcare charges and unplanned extended hospital admissions. This analysis suggests that efforts aiming at reducing rates of infections could result in substantial system savings, validating the need for increased efforts to prevent Amb-BSIs.

Trends in paediatric and adult bloodstream infections at a Ghanaian referral hospital: a retrospective study

Background

Bloodstream infections (BSI) are life-threatening emergencies. Identification of the common pathogens and their susceptibility patterns is necessary for timely empirical intervention.

Methods

We conducted a 4-year retrospective analysis of blood cultures from all patients excluding neonates at the Korle-Bu Teaching hospital, Ghana, from January 2010 through December 2013. Laboratory report data were used to determine BSI, blood culture contamination, pathogen profile, and antimicrobial resistance patterns.

Results

Overall, 3633 (23.16 %) out of 15,683 blood cultures were positive for various organisms. Pathogen-positive cultures accounted for 1451 (9.3 %, 95 % CI 8.5–9.8 %). Infants recorded the highest true blood culture positivity (20.9 %, n = 226/1083), followed by the elderly (13.3 %, n = 80/601), children (8.9 %, n = 708/8000) and adults (7.2 %, n = 437/6000) (p = 0.001 for Marascuilo’s post hoc). Overall occurrence of BSI declined with increasing age-group (p = 0.001) but the type of isolates did not vary with age except for Citrobacter, Escherichia coli, Klebsiella, Salmonella, and Enterococcus species. Gram negative bacteria predominated in our study (59.8 %, n = 867/1451), but the commonest bacterial isolate was Staphylococcus aureus (21.9 %, n = 318/1451)—and this trend run through the various age-groups. From 2010 to 2013, we observed a significant trend of yearly increase in the frequency of BSI caused by cephalosporin-resistant enterobacteria (Chi square for trend, p = 0.001). Meropenem maintained high susceptibility among all Gram-negative organisms ranging from 96 to 100 %. Among Staphylococcus aureus, susceptibility to cloxacillin was 76.6 %.

Conclusion

Our study shows a significantly high blood culture positivity in infants as compared to children, adults and the elderly. There was a preponderance of S. aureus and Gram-negative bacteria across all age-groups. Meropenem was the most active antibiotic for Gram-negative bacteria. Cloxacillin remains a very useful anti-staphylococcal agent.

Electronic supplementary material

The online version of this article (doi:10.1186/s12941-016-0163-z) contains supplementary material, which is available to authorized users.

Bringing central line-associated bloodstream infection prevention home: catheter maintenance practices and beliefs of pediatric oncology patients and families

BACKGROUND

A study was conducted to investigate (1) the extent to which best-practice central line maintenance practices were employed in the homes of pediatric oncology patients and by whom, (2) caregiver beliefs about central line care and central line-associated blood stream infection (CLABSI) risk, (3) barriers to optimal central line care by families, and (4) educational experiences and preferences regarding central line care.

METHODS

Researchers administered a survey to patients and families in a tertiary care pediatric oncology clinic that engaged in rigorous ambulatory and inpatient CLABSI prevention efforts.

RESULTS

Of 110 invited patients and caregivers, 105 participated (95% response rate) in the survey (March-May 2012). Of the 50 respondents reporting that they or another caregiver change central line dressings, 48% changed a dressing whenever it was soiled as per protocol (many who did not change dressings per protocol also never personally changed dressings); 67% reported the oncology clinic primarily cares for their child's central line, while 29% reported that an adult caregiver or the patient primarily cares for the central line. Eight patients performed their own line care "always" or "most of the time." Some 13% of respondents believed that it was "slightly likely" or "not at all likely" that their child will get an infection if caregivers do not perform line care practices perfectly every time. Dressing change practices were the most difficult to comply with at home. Some 18% of respondents wished they learned more about line care, and 12% received contradictory training. Respondents cited a variety of preferences regarding line care teaching, although the majority looked to clinic nurses for modeling line care.

CONCLUSIONS

Interventions aimed at reducing ambulatory CLABSIs should target appropriate educational experiences for adult caregivers and patients and identify ways to improve compliance with best-practice care.

The Changing Epidemiology of Bloodstream Infections and Resistance in Hematopoietic Stem Cell Transplantation Recipients

OBJECTIVE

Patients receiving hematopoietic stem cell transplantation (HSCT) are exposed to highly immunosuppressive conditions and bloodstream infections (BSIs) are one of the most common major complications within this period. Our aim, in this study, was to evaluate the epidemiology of BSIs in these patients retrospectively.

MATERIALS AND METHODS

The epidemiological properties of 312 patients with HSCT were retrospectively evaluated.

RESULTS

A total of 312 patients, followed between 2000 and 2011, who underwent autologous (62%) and allogeneic (38%) HSCT were included in the study. The most common underlying malignancies were multiple myeloma (28%) and Hodgkin lymphoma (21.5%). A total of 142 (45%) patients developed at least 1 episode of BSI and 193 separate pathogens were isolated from the blood cultures. There was a trend of increase in the numbers of BSIs in 2005-2008 and a relative increase in the proportion of gram-positive infections in recent years (2009-2011), and central venous catheter-related BSI was found to be most common source. Coagulase-negative staphylococci (49.2%) and Acinetobacter baumannii (8.8%) were the most common pathogens. Extended-spectrum beta-lactamase-producing strains were 23% and 22% among Escherichia coli and Klebsiella spp. isolates, respectively. Quinolone resistance was detected in 10% of Enterobacteriaceae. Resistance to carbapenems was not detected in Enterobacteriaceae, while it was seen at 11.1% and 23.5% in Pseudomonas and Acinetobacter strains, respectively.

CONCLUSION

A shift was detected from gram-negative bacteria to gram-positive in the etiology over the years and central lines were the most common sources of BSIs.

Catheter-Related Polymicrobial Bloodstream Infections among Pediatric Bone Marrow Transplant Outpatients—Atlanta, Georgia, 2007

Objective.

To identify risk factors for polymicrobial bloodstream infections (BSIs) in pediatric bone marrow transplant (BMT) outpatients attending a newly constructed clinic affiliated with a children's hospital.

Methods.

All 30 outpatients treated at a new BMT clinic during September 10-21, 2007, were enrolled in a cohort study. The investigation included interviews, medical records review, observations, and bacterial culture and molecular typing of patient and environmental isolates. Data were analyzed using exact conditional logistic regression.

Results.

Thirteen patients experienced BSIs caused by 16 different, predominantly gram-negative organisms. Presence of a tunneled catheter (odds ratio [OR], 19.9 [95% confidence interval {CI}, 2.4-∞), catheter access (OR, 13.7 [95% CI, 1.8-∞]), and flushing of a catheter with predrawn saline (OR, 12.9 [95% CI, 1.0-766.0]) were independently associated with BSI. The odds of experiencing a BSI increased by a factor of 16.8 with each additional injection of predrawn saline (95% CI, 1.8-827.0). Although no environmental source of pathogens was identified, interviews revealed breaches in recommended infection prevention practice and medication handling. Saline flush solutions were predrawn, and multiple doses were obtained from single-dose preservative-free vials to avoid delays in patient care.

Conclusion.

We speculate that infection prevention challenges in the new clinic, combined with successive needle punctures of vials, facilitated extrinsic contamination and transmission of healthcare-associated pathogens. We recommend that preservative-free single-use vials not be punctured more than once. Use of single-use prefilled saline syringes might prevent multiuse of single-use saline vials. Storage of saline outside a medication supply system might be advisable. Before opening new clinic facilities, hospitals should consider conducting a mock patient flow exercise to identify infection control challenges.

Risk factors associated with laboratory-confirmed bloodstream infections in a tertiary neonatal intensive care unit

BACKGROUND

Bloodstream infections (BSI) remain a leading cause of morbidity and mortality among infants admitted to neonatal intensive care units (NICUs). At the time of evaluation for suspected BSI, presenting signs may be nonspecific. We sought to determine the clinical signs and risk factors associated with laboratory-confirmed BSI among infants evaluated for late-onset sepsis in a tertiary NICU.

METHODS

This prospective cohort study included infants >3 days of age admitted to a level 4 NICU from July 2006 to October 2009 for whom a blood culture was drawn for suspected sepsis. Clinicians documented presenting signs at the time of culture. Laboratory-confirmed BSI was defined as per the National Healthcare Safety Network. Multivariate analyses were performed using a logistic regression random effects model.

RESULTS

Six-hundred and eighty eligible episodes of suspected BSI were recorded in 409 infants. Enteral contrast within the preceding 48 hours was the most significant risk factor for laboratory-confirmed BSI [Odds Ratio: 9.58 (95% confidence interval: 2.03-45.19)] followed by presence of a central venous catheter. Apnea and hypotension were the most strongly associated presenting signs.

CONCLUSION

Among infants evaluated in a tertiary NICU, recent exposure to enteral contrast was associated with increased odds of developing BSI. Apnea and hypotension were the most strongly associated clinical signs of infection.

Prevention of transmission of multidrug-resistant organisms during catheter exchange using antimicrobial catheters

Exchanging a central venous catheter (CVC) over a guide wire for a fresh uncoated CVC in the presence of bacteremia can result in cross-infection of the newly exchanged CVC. A recent retrospective clinical study showed that exchanging a catheter over a guide wire in the presence of bacteremia using an antimicrobial minocycline-rifampin (M/R) catheter may improve outcomes. To expand on this, we developed an in vitro cross-contamination model of exchange to evaluate the efficacy of different antimicrobial CVCs in preventing cross-contamination of multidrug-resistant organisms during exchange. Uncoated CVCs were allowed to form biofilm by methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. After 24 h, the biofilm-colonized CVCs were placed in a glass tube containing bovine calf serum plus Mueller-Hinton broth, and each catheter was exchanged over a guide wire for a fresh uncoated or an M/R-, chlorhexidine-silver sulfadiazine (CHX/SS)-, or chlorhexidine-M/R (CHX-M/R)-coated CVC. Cross-contamination of exchanged catheters was enumerated by sonication and quantitative plating methods. The exchange of M/R CVCs completely prevented cross-contamination by MRSA biofilms compared to control exchanged CVCs (P<0.0001). Exchange with CHX/SS CVCs reduced but did not completely prevent cross-contamination by MRSA (P=0.005). Exchange with CHX-M/R CVCs completely prevented cross-contamination by MRSA, P. aeruginosa, and C. albicans biofilms (P<0.0001). Furthermore, CHX-M/R CVCs were superior to M/R CVCs against P. aeruginosa and C. albicans (P=0.003) and were superior to CHX/SS CVCs against MRSA and P. aeruginosa (P=0.01). In conclusion, exchange with the novel CHX-M/R CVC was the only exchange effective in completely and concurrently preventing cross-contamination from bacteria and Candida.

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

Background

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

Methods

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

Results

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

Conclusion

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

Polymicrobial bloodstream infection in neonates: microbiology, clinical characteristics, and risk factors

Background

Polymicrobial bloodstream infections (PBSIs) have been associated with complex underlying medical conditions and a high incidence of specific microorganisms in several settings, but the relevant data are scarce in neonates.

Methods

Positive blood cultures from January 2004 to December 2011 in the neonatal intensive care unit (NICU) of Chang Gung Memorial Hospital (CGMH) were reviewed. Each neonate with PBSI (case episode) was matched to two episodes of monomicrobial BSI (control episode) by birth weight, gestational age and gender. Records were reviewed to compare their underlying medical conditions, organisms isolated, adequacy of therapy, clinical characteristics and outcomes.

Results

Forty-five episodes of PBSI (4.4% of all neonatal BSIs) were identified in 43 neonates. Gram-negative organisms constituted 59.8% of all PBSI pathogens, and 33 (73.3%) of PBSIs were caused by at least one Gram-negative organism. PBSIs were significantly more likely to be the recurrent episode and have endotracheal tube in place. No significant difference was found between PBSIs and controls in terms of demographics and most chronic conditions. PBSIs were significantly associated with a higher severity of illness, a longer duration of septic symptoms, and a higher rate of modification of antimicrobial regimens than monomicrobial BSIs. However, the sepsis-attributable mortality rates were comparable between these two groups.

Conclusions

In the NICU, PBSIs were more often caused by Gram-negative bacilli, and often occurred in neonates without any chronic conditions. The clinical significance of PBSIs included a more severe illness, longer duration of septic symptoms and a higher rate of modification of antimicrobial regimens.

Biofilm extracellular DNA enhances mixed species biofilms of Staphylococcus epidermidis and Candida albicans

BACKGROUND

Polymicrobial infections are responsible for significant mortality and morbidity in adults and children. Staphylococcus epidermidis and Candida albicans are the most frequent combination of organisms isolated from polymicrobial infections. Vascular indwelling catheters are sites for mixed species biofilm formation and pose a significant risk for polymicrobial infections. We hypothesized that enhancement of biofilms in a mixed species environment increases patient mortality and morbidity.

RESULTS

Mixed species biofilms of S. epidermidis and C. albicans were evaluated in vitro and in a subcutaneous catheter infection model in vivo. Mixed species biofilms were enhanced compared to single species biofilms of either S. epidermidis or C. albicans. A mixed species environment increased catheter infection and increased dissemination of S. epidermidis in mice. Microarrays were used to explore differential gene expression of S. epidermidis in the mixed species biofilms. In mixed species biofilms, compared to single species S. epidermidis biofilms, 2.7% of S. epidermidis genes were upregulated and 6% were down regulated. Staphylococcal autolysis repressors lrgA and lrgB were down regulated 36-fold and 27-fold respectively. The role of biofilm extracellular DNA was investigated by quantitation and by evaluating the effects of DNAse in a concentration and time dependent manner. S. epidermidis specific eDNA was increased in mixed species biofilms and further confirmed by degradation with DNAse.

CONCLUSIONS

Mixed-species biofilms are enhanced and associated with increased S. epidermidis-specific eDNA in vitro and greater systemic dissemination of S. epidermidis in vivo. Down regulation of the lrg operon, a repressor of autolysis, associated with increased eDNA suggests a possible role for bacterial autolysis in mixed species biofilms. Enhancement and systemic dissemination of S. epidermidis may explain adverse outcomes after clinical polymicrobial infections of S. epidermidis and C. albicans.

Ambulatory pediatric oncology CLABSIs: epidemiology and risk factors

BACKGROUND

To compare the burden of central line-associated bloodstream infections (CLABSIs) in ambulatory versus inpatient pediatric oncology patients, and identify the epidemiology of and risk factors associated with ambulatory CLABSIs.

PROCEDURE

We prospectively identified infections and retrospectively identified central line days and characteristics associated with CLABSIs from January 2009 to October 2010. A nested case-control design was used to identify characteristics associated with ambulatory CLABSIs.

RESULTS

We identified 319 patients with central lines. There were 55 ambulatory CLABSIs during 84,705 ambulatory central line days (0.65 CLABSIs per 1,000 central line days (95% CI 0.49, 0.85)), and 19 inpatient CLABSIs during 8,682 inpatient central line days (2.2 CLABSIs per 1,000 central lines days (95% CI 1.3, 3.4)). In patients with ambulatory CLABSIs, 13% were admitted to an intensive care unit and 44% had their central lines removed due to the CLABSI. A secondary analysis with a sub-cohort, suggested children with tunneled, externalized catheters had a greater risk of ambulatory CLABSI than those with totally implantable devices (IRR 20.6, P < 0.001). Other characteristics independently associated with ambulatory CLABSIs included bone marrow transplantation within 100 days (OR 16, 95% CI 1.1, 264), previous bacteremia in any central line (OR 10, 95% CI 2.5, 43) and less than 1 month from central line insertion (OR 4.2, 95% CI 1.0, 17).

CONCLUSIONS

In pediatric oncology patients, three times more CLABSIs occur in the ambulatory than inpatient setting. Ambulatory CLABSIs carry appreciable morbidity and have identifiable, associated factors that should be addressed in future ambulatory CLABSI prevention efforts.

Central line maintenance bundles and CLABSIs in ambulatory oncology patients

OBJECTIVE

Pediatric oncology patients are frequently managed with central lines as outpatients, and these lines confer significant morbidity in this immune-compromised population. We aimed to investigate whether a multidisciplinary, central line maintenance care bundle reduces central line-associated bloodstream infections (CLABSIs) and bacteremias in ambulatory pediatric oncology patients.

METHODS

We conducted an interrupted time-series study of a maintenance bundle concerning all areas of central line care. Each of 3 target groups (clinic staff, homecare agency nurses, and patient families) (1) received training on the bundle and its importance, (2) had their practice audited, and (3) were shown CLABSI rates through graphs, in-service training, and bulletin boards. CLABSI and bacteremia person-time incidence rates were collected for 23 months before and 24 months after beginning the intervention and were compared by using a Poisson regression model.

RESULTS

The mean CLABSI rate decreased by 48% from 0.63 CLABSIs per 1000 central line days at baseline to 0.32 CLABSIs per 1000 central line days during the intervention period (P = .005). The mean bacteremia rate decreased by 54% from 1.27 bacteremias per 1000 central line days at baseline to 0.59 bacteremias per 1000 central line days during the intervention period (P < .001).

CONCLUSIONS

Implementation of a multidisciplinary, central line maintenance care bundle significantly reduced CLABSI and bacteremia person-time incidence rates in ambulatory pediatric oncology patients with central lines. Further research is needed to determine if maintenance care bundles reduce ambulatory CLABSIs and bacteremia in other adult and pediatric populations.

Bringing central line-associated bloodstream infection prevention home: CLABSI definitions and prevention policies in home health care agencies

BACKGROUND

A study was conducted to investigate health care agency central line-associated bloodstream infection (CLABSI) definitions and prevention policies and pare them to the Joint Commission National Patient Safety Goal (NPSG.07.04.01), the Centers for Disease Control and Prevention (CDC) CLABSI prevention recommendations, and a best-practice central line care bundle for inpatients.

METHODS

A telephone-based survey was conducted in 2011 of a convenience sample of home health care agencies associated with children's hematology/oncology centers.

RESULTS

Of the 97 eligible home health care agencies, 57 (59%) completed the survey. No agency reported using all five aspects of the National Healthcare and Safety Network/Association for Professionals in Infection Control and Epidemiology CLABSI definition and adjudication process, and of the 50 agencies that reported tracking CLABSI rates, 20 (40%) reported using none. Only 10 agencies (18%) had policies consistent with all elements of the inpatient-focused NPSG.07.04.01, 10 agencies (18%) were consistent with all elements of the home care targeted CDC CLABSI prevention recommendations, and no agencies were consistent with all elements of the central line care bundle. Only 14 agencies (25%) knew their overall CLABSI rate: mean 0.40 CLABSIs per 1,000 central line days (95% confidence interval [CI], 0.18 to 0.61). Six agencies (11%) knew their agency's pediatric CLABSI rate: mean 0.54 CLABSIs per 1,000 central line days (95% CI, 0.06 to 1.01).

CONCLUSIONS

The policies of a national sample of home health care agencies varied significantly from national inpatient and home health care agency targeted standards for CLABSI definitions and prevention. Future research should assess strategies for standardizing home health care practices consistent with evidence-based recommendations.

Mixed bloodstream infections involving bacteria and Candida spp

OBJECTIVES

Polymicrobial bloodstream infection (BSI) is an imprecisely defined entity purportedly associated with a worse outcome than monomicrobial BSI. This study examines trends in BSI episodes caused by bacteria and Candida spp. (mixed-BSI) in a large teaching hospital.

METHODS

All episodes of BSI from January 2000 to December 2010 were reviewed. Three groups (n = 54 each) of patients were compared: all adults with mixed-BSI from January 2006 to December 2010 (cases) and randomly selected patients with polybacterial BSI (polyB-BSI) (Control 1) or Candida spp. BSI (Candida-BSI) (Control 2) in this same period.

RESULTS

A total of 139 episodes of mixed-BSI were recorded (0.7% of all BSI, 6.9% of all poly-BSI and 18.0% of all Candida-BSI episodes). The incidence of mixed-BSI was 0.21 cases/1000 admissions, increasing from 0.08 (2000) to 0.34 (2010) cases/1000 admissions (P = 0.007). Mixed-BSI represented 11.8% and 22.9% of all episodes of candidaemia in 2000 and 2010, respectively (P = 0.011). Compared with polyB-BSI, mixed-BSI patients showed fewer malignancies, more frequent nosocomial or intravenous catheter BSI source and less frequent intra-abdominal origin, were more frequently admitted to an intensive care unit (ICU), received more antimicrobials and showed a longer hospital stay and higher mortality. Compared with Candida-BSI, mixed-BSI patients showed more severe underlying diseases, were more frequently admitted to an ICU or oncology-haematology unit, showed a higher APACHE II score, more often progressed to septic shock or multiorgan failure and received more antimicrobials. Mortality was similar.

CONCLUSIONS

Mixed-BSI is a rare, distinct infection with a worse prognosis than polyB-BSI. We were unable to detect differences in the prognosis of mixed-BSI when compared with Candida-BSI.

Implementation of a central line maintenance care bundle in hospitalized pediatric oncology patients

OBJECTIVE

To investigate whether a multidisciplinary, best-practice central line maintenance care bundle reduces central line-associated blood stream infection (CLABSI) rates in hospitalized pediatric oncology patients and to further delineate the epidemiology of CLABSIs in this population.

METHODS

We performed a prospective, interrupted time series study of a best-practice bundle addressing all areas of central line care: reduction of entries, aseptic entries, and aseptic procedures when changing components. Based on a continuous quality improvement model, targeted interventions were instituted to improve compliance with each of the bundle elements. CLABSI rates and epidemiological data were collected for 10 months before and 24 months after implementation of the bundle and compared in a Poisson regression model.

RESULTS

CLABSI rates decreased from 2.25 CLABSIs per 1000 central line days at baseline to 1.79 CLABSIs per 1000 central line days during the intervention period (incidence rate ratio [IRR]: 0.80, P = .58). Secondary analyses indicated CLABSI rates were reduced to 0.81 CLABSIs per 1000 central line days in the second 12 months of the intervention (IRR: 0.36, P = .091). Fifty-nine percent of infections resulted from Gram-positive pathogens, 37% of patients with a CLABSI required central line removal, and patients with Hickman catheters were more likely to have a CLABSI than patients with Infusaports (IRR: 4.62, P = .02).

CONCLUSIONS

A best-practice central line maintenance care bundle can be implemented in hospitalized pediatric oncology patients, although long ramp-up times may be necessary to reap maximal benefits. Further research is needed to determine if this CLABSI rate reduction can be sustained and spread.

Catheter-related infections in pediatric patients with cancer

Central venous catheters (CVCs) are essential in the management of pediatric patients receiving antineoplastic therapy or bone marrow transplants, and have significantly improved their quality of life, but CVC-related infectious complications are a major source of morbidity. It has been estimated that 14-51 % of the CVCs implanted in children with malignancies may be complicated by bacteremia, and that the incidence of infections is 1.4-1.9 episodes per 1,000 CVC days. However, there are few recent data concerning the epidemiology of CVC-related infections, the prevalence of antimicrobial resistance in their etiology, or the main factors associated with an increased risk of infection by type of catheter, patient age, the type of cancer, or the presence of neutropenia. Moreover, although various new strategies have been proposed in an attempt to reduce the risk of CVC-related infections, such as catheters impregnated with antiseptics/antibiotics, lock antibiotic prophylaxis, the use of ointments at the exit site, and antithrombotic prophylaxis, their real efficacy in children has not yet been demonstrated. The management of CVC-related infections remains difficult, mainly because of the number of still open questions (including the choice of optimal antimicrobial therapy because of the increasing isolation of multiresistant bacterial strains, treatment duration, whether catheters should be removed or not, the feasibility of guidewire exchange, and the usefulness of antibiotic lock therapy) and the lack of studies of children with cancer. Only well-designed, prospective clinical trials involving pediatric cancer patients can clarify optimal prevention and treatment strategies for CVC-related infections in this population.

Preventive strategies for central line-associated bloodstream infections in pediatric hematopoietic stem cell transplant recipients

BACKGROUND

Few studies have described preventive strategies for central line-associated bloodstream infections (CLABSIs) in pediatric hematopoietic stem cell transplantation (HSCT) recipients.

METHODS

We performed a pilot intervention study in our pediatric HSCT population in 2006-2008 and compared CLABSI rates before and after implementation of preventive strategies (ie, training staff and caregivers in procedures for dressing changes and drawing blood) in the inpatient, outpatient, and non-health care (ie, home) settings. We also studied the pathogens associated with hospital-onset versus community-onset CLABSIs.

RESULTS

During the study period, 90 children (median age, 10 years) underwent HSCT. Fifty-nine children (66%) developed a CLABSI; 18 in the hospital, 27 in the community, and 14 in both settings. After implementation of central line (CL) maintenance care strategies, the overall CLABSI rate declined from 10.03 to 3.00 CLABSIs per 1,000 CL-days (rate ratio, 0.3; 95% confidence interval, 0.2-0.5, P < .0001) and rates declined for both hospital- and community-onset CLABSIs. Gram negative pathogens caused more community-onset (45/65, 69%) than hospital-onset (22/46, 48%) CLABSIs (odds ratio, 2.5; 95% confidence interval, 1.1-5.4; P = .02).

CONCLUSIONS

Standardization of care practices for CL maintenance was associated with a reduction of CLABSIs in our pediatric HSCT population. A multicenter study is needed to confirm these observations.

Clinical significance and outcome of polymicrobial Staphylococcus aureus bacteremia

OBJECTIVES

The clinical significance of polymicrobial Staphylococcus aureus bacteremia (SAB) remains unclear. We therefore compared the clinical features and outcomes of polymicrobial and monomicrobial SAB.

METHODS

A prospective cohort study of patients with SAB was performed during a 20-months. Polymicrobial SAB was defined as the simultaneous isolation of S. aureus and other microorganisms from blood cultures. However, Corynebacterium spp., Bacillus spp., and coagulase-negative staphylococci were considered contaminants unless they were related to device infection and grew in two or more blood cultures.

RESULTS

During the study period, 44 (10%) patients had polymicrobial and 412 (90%) had monomicrobial SAB. A total of 54 microorganisms were isolated from the former, with Enterococcus spp. (22%) being the most common. Independent risk factors for polymicrobial SAB included neutropenia (odds ratio [OR] 3.5, p = 0.02), biliary tract catheters (OR 5.0, p = 0.001), and intra-abdominal infection (OR 10.3, p < 0.001). Clinical outcomes were significantly worse among patients with polymicrobial than monomicrobial SAB, including bacteremia-related and 7-day mortality rates. Independent predictors of bacteremia-related mortality were solid tumors (HR 2.0, p = 0.03) and polymicrobial SAB (HR 2.8, p = 0.007).

CONCLUSIONS

Polymicrobial SAB is associated with more severe illness than monomicrobial SAB, with neutropenia, biliary tract catheters and intra-abdominal infection being significant risk factors for polymicrobial SAB.

Pediatric patients with intravascular devices: polymicrobial bloodstream infections and risk factors

A retrospective study was conducted, including 61 patients with long-term intravascular devices (IVDs) admitted to the Childrens Hospital Los Angeles with diverse underlying diseases, different types of catheters, and culture-proven catheter-related bloodstream infections (BSIs). Within these patients, 125 catheter-related BSIs occurred, and the incidence of monomicrobial and polymicrobial BSIs was evaluated. Risk factors for polymicrobial BSIs were determined. Forty-two BSIs contained more than one pathogen. These polymicrobial BSIs were observed more often in younger patients (<4.1 years versus ≥4.1 years) and less in patients using venous implanted ports. No other associations were found between the occurrences of polymicrobial BSIs and underlying diseases, other types of catheters, host defense status, parenteral nutrition, recurrences, or catheter removal. Patients with long-term IVDs at a younger age have a higher risk of developing a polymicrobial BSI. Future prospective studies should address the issue of polymicrobial infection in IVDs in more detail.

Characteristics and outcomes of polymicrobial bloodstream infections in the emergency department: A matched case-control study

OBJECTIVES

Polymicrobial bloodstream infection (BSI) is a critical condition and has been increasingly reported; however, the authors were unable to find an emergency department (ED) patient-based study in the literature.

METHODS

A retrospective matched case-control study with a ratio of 1:3 among patients with polymicrobial BSIs in an ED was conducted. The case group was patients aged > 16 years with polymicrobial BSIs. Patients matched for age and sex with monomicrobial BSIs were sampled as the control group. Demographic information, underlying conditions, microbiologic data, and outcomes were collected for further analysis.

RESULTS

From January 2005 to December 2007, a total of 112 episodes of polymicrobial BSIs among 109 patients were included. Two pathogens were isolated among 87 (77.7%) episodes and three were found among 25 (22.3%) episodes. A history of hospitalization within 90 days was an independent risk factor for polymicrobial BSIs (p = 0.003). Intraabdominal infection (p < 0.001) and respiratory tract infection (p = 0.017) were more likely to be associated with polymicrobial BSIs. Gram-negative and Gram-positive bacteria were documented in 95.5 and 46.4% episodes of polymicrobial BSIs, respectively. Inappropriate antimicrobial treatment was observed in 53.6% of polymicrobial BSIs, but only accounted for 23.8% of monomicrobial BSIs (p < 0.001). The overall 30-day mortality rate of the polymicrobial group was significantly higher than those with monomicrobial BSIs (30.3 and 11.6%, respectively; p < 0.001).

CONCLUSIONS

Patients with polymicrobial BSIs had a high mortality rate. Acknowledgment of the clinical and microbiologic characteristics and recognition of patients at risk for polymicrobial BSIs are critical in EDs.