Clostridium difficile infection is a risk factor for bacteremia due to vancomycin-resistant enterococci (VRE) in VRE-colonized patients with acute leukemia

Liberation of host heme by Clostridioides difficile-mediated damage enhances Enterococcus faecalis fitness during infection

IMPORTANCE

Clostridioides difficile and Enterococcus faecalis are two pathogens of great public health importance. Both bacteria colonize the human gastrointestinal tract where they are known to interact in ways that worsen disease outcomes. We show that the damage associated with C. difficile infection (CDI) releases nutrients that benefit E. faecalis. One particular nutrient, heme, allows E. faecalis to use oxygen to generate energy and grow better in the gut. Understanding the mechanisms of these interspecies interactions could inform therapeutic strategies for CDI.

Increased Incidence and Risk of Septicemia and Urinary Tract Infection After Clostridioides difficile Infection

Background

Although increased occurrence of septicemia in persons with Clostridioides difficile infection (CDI) has been reported, incidence rates and risk of septicemia and urinary tract infection (UTI) after CDI are unclear.

Methods

The first episode of CDI was identified using 2011-2017 MarketScan and CMS Medicare data and CDI cases categorized by standard surveillance definitions. Uninfected persons were frequency matched 4:1 to cases by the CDI case surveillance definition. Multivariable Cox proportional hazards models were used to identify risk factors for septicemia and UTI within 90 days of CDI onset, accounting for the competing risk of death in the Medicare population.

Results

The incidence of septicemia was highest after hospital-onset CDI in the Medicare, younger commercial, and younger Medicaid populations (25.5%, 15.7%, and 19.5%, respectively) and lowest in those with community-associated CDI (3.8%, 4.3%, and 8.3%, respectively). In contrast, the incidence of UTI was highest in those with other healthcare facility onset CDI in all 3 populations (32.1%, 24.2%, and 18.1%, respectively). Hospital-onset CDI was associated with highest risk of septicemia compared with uninfected controls in all 3 populations. In the younger populations, risk of septicemia was more uniform across the CDI surveillance definitions. The risk of UTI was significantly higher in all CDI surveillance categories compared to uninfected controls, and among CDI cases it was lowest in those with community-associated CDI.

Conclusions

The incidence of septicemia is high after CDI, particularly after hospital-onset infection. Additional preventive measures are needed to reduce infectious complications of CDI.

Incidence of infection with multidrug-resistant Gram-negative bacteria and vancomycin-resistant enterococci in carriers: a systematic review and meta-regression analysis

BACKGROUND

Carriers of multidrug-resistant bacteria are at risk of infections with these bacteria; the precise size of this risk is unclear. We aimed to quantify the effect of gut colonisation on subsequent risk of infection with multidrug-resistant bacteria.

METHODS

We performed a systematic review and meta-regression analysis. We searched PubMed, Embase, Web of Science Core Collection, and Google Scholar for follow-up studies published from Jan 1, 1995, to March 17, 2022, that measured the incidence of infections with multidrug-resistant Gram-negative bacteria (MDR-GNB) and from Jan 1, 1995, to March 15, 2022, that measured the incidence of infections with vancomycin-resistant enterococci (VRE). We included original cohort studies and case-control studies that used incidence-density sampling, included 50 or more patients with enteric colonisation or positive urinary samples as a surrogate marker of colonisation, or both, and analysed infections clearly preceded by colonisation. We did not use any language restrictions. We excluded studies not reporting length of follow-up. Summary data were extracted and independently cross-verified by two authors. Carriage was defined as MDR-GNB or VRE, detected in faecal or urinary cultures. Our primary outcomes were cumulative incidence and incidence density of infection in patients colonised by multidrug-resistant bacteria. To estimate pooled incidences, general linearised mixed-effects meta-regressions were used, adjusting for varying follow-up durations. This study is registered with PROSPERO, CRD42020222415.

FINDINGS

Of the 301 studies identified, 44 studies (26 on MDR-GNB, 14 on VRE, and four on both MDR-GNB and VRE) from 14 countries were retained for qualitative synthesis, 40 of which were analysed with meta-regression, comprising data for 14 049 patients colonised with multidrug-resistant bacteria. The pooled cumulative incidence of infection was 14% (95% CI 10-18; p<0·0001) at a median follow-up time of 30 days for MDR-GNB (845 cases of infection in 9034 patients colonised) and 8% (5-13; p<0·0001) at 30 days for VRE (229 cases of infection in 4747 patients colonised). Infection incidence density (4·26 infections per 1000 patient-days; 95% CI 1·69-6·82) and cumulative incidence of infection (19%, 95% CI 15-25; p<0·0001; 602 cases of infection in 4547 patients colonised) were highest for carbapenem-resistant Gram-negative bacteria at 30 days. Risk of bias was rated low to moderate.

INTERPRETATION

The risk of infection was substantial, with the highest risk for patients colonised with carbapenem-resistant Gram-negative bacteria and the lowest in patients with VRE. These data might help to guide prophylactic and treatment decisions and form a valuable resource for planning clinical trials on targeted prevention.

FUNDING

The Netherlands Organization for Health Research and Development.

Trends of Vancomycin-Resistant Enterococcus Infections in Cancer Patients

Objective Vancomycin-resistant Enterococcus (VRE) is an important cause of infection in immunocompromised populations. In Pakistan, very limited data are available regarding Enterococcus infection and its outcomes. We conducted this study to evaluate the trends including risk factors, treatment options, and outcomes of infections due to vancomycin-resistant enterococci in cancer patients in Pakistan. Methods We conducted a retrospective observational study. We extracted data from medical records of our center over a period of seven years. All admitted cancer patients with any vancomycin-resistant Enterococcus positive culture were included. The following parameters were evaluated: age, gender, type of cancer, febrile neutropenia, prior antibiotics, admission, comorbidities, system-wise infections (including bacteremia, catheter-related infection, pneumonia, urinary tract infections, intra-abdominal infection, bone and joint infections, skin and skin structure infections), intensive care unit admission, and 30-day all-cause mortality. Frequencies of infections, mortality, and drug susceptibility were evaluated over the course of seven years. Results Risk factors for enterococcal infection included prior exposure of piperacillin/tazobactam (n=209, 86.7%), meropenem (n=132, 54.8%), vancomycin (n=126, 52.3%), metronidazole (n=67, 27.8%), prior admission for more than 48 hours (n=198, 82.2%), and comorbidities (n=76, 31.5%), with acute kidney injury being most common (n=72, 95%) followed by diabetes mellitus (n=70, 92.1%). Precursor B cell acute lymphoblastic leukemia (pre-B ALL) was the most common malignancy in which infection occurred (n=54, 38.3%). Among patients who developed infection, 46% (n=111) had febrile neutropenia. Enterococcus species caused infection in 61% (n=147) and Enterococcus faecium in 39% (n=94). Bacteremia occurred in 45.2% (n=109) patients followed by urinary tract and intra-abdominal infection; 45.6% (n=110) patients were admitted to ICU, and 30-day all-cause mortality was 44.8% (n=108). Linezolid sensitivity was 100%. The total number of enterococci infections decreased over seven years. Frequency of E. species infection, bacteremia, intra-abdominal, skin-related infections, and recurrent infection also decreased, but the frequency of E. facium infections, ICU admission, and 30-day all-cause mortality was increased. Conclusion VRE infections have become less frequent but more severe in recent years with increase in mortality. Prior use of antibiotics (including piperacillin/tazobactam, vancomycin, carbapenems, and metronidazole), diagnosis of hematological malignancy, febrile neutropenia, diabetes mellitus, and renal failure are the risk factors for VRE infection. Bacteremia was the most common infection with high mortality rate. All strains remain sensitive to linezolid. Patients with these risk factors should be worked up for VRE and can be treated with linezolid empirically.

Concurrent and Subsequent Co-Infections of Clostridioides difficile Colitis in the Era of Gut Microbiota and Expanding Treatment Options

We narratively reviewed the physiopathology, epidemiology, and management of co-infections in Clostridioides difficile colitis (CDI) by searching the following keywords in Embase, MedLine, and PubMed: “Clostridium/Clostridioides difficile”, “co-infection”, “blood-stream infection” (BSI), “fungemia”, “Candida”, “Cytomegalovirus”, “probiotics”, “microbial translocation” (MT). Bacterial BSIs (mainly by Enterobacteriaceae and Enterococcus) and fungemia (mainly by Candida albicans) may occur in up to 20% and 9% of CDI, increasing mortality and length of hospitalization. Up to 68% of the isolates are multi-drug-resistant bacteria. A pivotal role is played by gut dysbiosis, intestinal barrier leakage, and MT. Specific risk factors are represented by CDI-inducing broad-spectrum antibiotics, oral vancomycin use, and CDI severity. Probiotics administration (mainly Saccharomyces and Lactobacillus) during moderate/severe CDI may favor probiotics superinfection. Other co-infections (such as Cytomegalovirus or protozoa) can complicate limited and specific cases. There is mounting evidence that fidaxomicin, bezlotoxumab, and fecal microbiota transplantation can significantly reduce the rate of co-infections compared to historical therapies by interrupting the vicious circle between CDI, treatments, and MT. Bacterial BSIs and candidemia represent the most common co-infections in CDI. Physicians should be aware of this complication to promptly diagnose and treat it and enforce preventive strategies that include a more comprehensive consideration of newer treatment options.

Neutropenic Enterocolitis and Sepsis: Towards the Definition of a Pathologic Profile

Background: Neutropenic enterocolitis (NE), which in the past was also known as typhlitis or ileocecal syndrome for the segment of the gastrointestinal tract most affected, is a nosological entity that is difficult to diagnose and whose pathogenesis is not fully known to date. Initially described in pediatric patients with leukemic diseases, it has been gradually reported in adults with hematological malignancies and non-hematological conditions, such as leukemia, lymphoma, multiple myeloma, aplastic anemia, and also myelodysplastic syndromes, as well as being associated with other immunosuppressive causes such as AIDS treatment, therapy for solid tumors, and organ transplantation. Therefore, it is associated with high mortality due to the rapid evolution in worse clinical pictures: rapid progression to ischemia, necrosis, hemorrhage, perforation, multisystem organ failure, and sepsis. Case report: A case report is included to exemplify the clinical profile of patients with NE who develop sepsis. Literature Review: To identify a specific profile of subjects affected by neutropenic enterocolitis and the entity of the clinical condition most frequently associated with septic evolution, a systematic review of the literature was conducted. The inclusion criteria were as follows: English language, full-text availability, human subjects, and adult subjects. Finally, the papers were selected after the evaluation of the title and abstract to evaluate their congruity with the subject of this manuscript. Following these procedures, 19 eligible empirical studies were included in the present review. Conclusions: Despite the recent interest and the growing number of publications targeting sepsis and intending to identify biomarkers useful for its diagnosis, prognosis, and for the understanding of its pathogenesis, and especially for multi-organ dysfunction, and despite the extensive research period of the literature review, the number of publications on the topic “neutropenic enterocolitis and sepsis” appears to be very small. In any case, the extrapolated data allowed us to conclude that the integration of medical history, clinical and laboratory data, radiological imaging, and macroscopic and histological investigations can allow us to identify a specific pathological profile.

Microbiota restoration reduces antibiotic-resistant bacteria gut colonization in patients with recurrent Clostridioides difficile infection from the open-label PUNCH CD study

BACKGROUND

Once antibiotic-resistant bacteria become established within the gut microbiota, they can cause infections in the host and be transmitted to other people and the environment. Currently, there are no effective modalities for decreasing or preventing colonization by antibiotic-resistant bacteria. Intestinal microbiota restoration can prevent Clostridioides difficile infection (CDI) recurrences. Another potential application of microbiota restoration is suppression of non-C. difficile multidrug-resistant bacteria and overall decrease in the abundance of antibiotic resistance genes (the resistome) within the gut microbiota. This study characterizes the effects of RBX2660, a microbiota-based investigational therapeutic, on the composition and abundance of the gut microbiota and resistome, as well as multidrug-resistant organism carriage, after delivery to patients suffering from recurrent CDI.

METHODS

An open-label, multi-center clinical trial in 11 centers in the USA for the safety and efficacy of RBX2660 on recurrent CDI was conducted. Fecal specimens from 29 of these subjects with recurrent CDI who received either one (N = 16) or two doses of RBX2660 (N = 13) were analyzed secondarily. Stool samples were collected prior to and at intervals up to 6 months post-therapy and analyzed in three ways: (1) 16S rRNA gene sequencing for microbiota taxonomic composition, (2) whole metagenome shotgun sequencing for functional pathways and antibiotic resistome content, and (3) selective and differential bacterial culturing followed by isolate genome sequencing to longitudinally track multidrug-resistant organisms.

RESULTS

Successful prevention of CDI recurrence with RBX2660 correlated with taxonomic convergence of patient microbiota to the donor microbiota as measured by weighted UniFrac distance. RBX2660 dramatically reduced the abundance of antibiotic-resistant Enterobacteriaceae in the 2 months after administration. Fecal antibiotic resistance gene carriage decreased in direct relationship to the degree to which donor microbiota engrafted.

CONCLUSIONS

Microbiota-based therapeutics reduce resistance gene abundance and resistant organisms in the recipient gut microbiome. This approach could potentially reduce the risk of infections caused by resistant organisms within the patient and the transfer of resistance genes or pathogens to others.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01925417 ; registered on August 19, 2013.

Risk factors for development of vancomycin-resistant enterococcal bacteremia among VRE colonizers : A retrospective case control study

AIMS

We aimed to determine the proportion of vancomycin-resistant enterococci (VRE) colonized patients among all inpatients who later developed VRE bacteremia during hospital stay and to identify the risk factors for VRE bacteremia at a tertiary hospital.

MATERIAL AND METHODS

Patients with positive rectal screening or any clinically significant positive culture results for VRE were included in 1‑year follow-up. Colonization with VRE was defined as a positive culture (rectal, stool, urinary) for VRE without infection and VRE bacteremia was defined as positive blood culture if the signs and symptoms were compatible with infection. To determine the risk factors for VRE bacteremia among VRE colonized patients, a retrospective case control study was performed. The two groups were compared in terms of variables previously defined as risk factors in the literature.

RESULTS

Of 947 positive samples, 17 VRE bacteremia were included in the analysis. Cephalosporin use for more than 3 days within 3 months was a significant risk factor for bacteremia (p = 0.008). Prior use of carbapenems was found to be statistically significant for bacteremia (p = 0.007). In multivariate analyses the use of carbapenems and cephalosporins was an independent risk factor for developing bacteremia among VRE colonizers (odds ratio, OR, 6.67; 95% confidence interval, CI, 1.30-34; p = 0.022 and OR 4.32, 95% CI 1.23-15; p = 0.022, respectively).

CONCLUSION

A VRE colonization in patients receiving broad-spectrum beta-lactam antibiotics including carbapenems and cephalosporins may result in bacteremia. It is possible to keep mortality at very low levels in VRE bacteremia with effective infection control measures, rapid infectious diseases consultation and rational antimicrobial treatment based on current epidemiological data.

Impact of Clostridioides difficile infection on the outcome of patients receiving a hematopoietic stem cell transplantation

OBJECTIVES

Clostridioides difficile infections (CDI) are common in autologous (auto-HSCT) or allogenic hematopoietic stem cell transplant (allo-HSCT) recipients. However, the impact of CDI on patient outcomes is controversial. We conducted this study to examine the impact of CDI on patient outcomes.

METHODS

We performed a retrospective single-center study, including 191 lymphoma patients receiving an auto-HSCT and 276 acute myeloid leukemia (AML) patients receiving an allo-HSCT. The primary endpoint was overall survival (OS). Secondary endpoints were causes of death and, for the allo-HSCT cohort, GvHD- and relapse-free survival (GRFS).

RESULTS

The prevalence of CDI was 17.6% in the AML allo-HSCT and 7.3% in the lymphoma auto-HSCT cohort. A higher prevalence of bloodstream infections, but no differences concerning OS or cause of death were found for patients with CDI in the auto-HSCT cohort. [AU] In the allo-HSCT cohort, OS and GRFS were similar between CDI and non-CDI patients. However, the leading cause of death was relapse among non-CDI patients, but it was infectious diseases in the CDI group with fewer deaths due to relapse.

CONCLUSIONS

CDI was not associated with worse survival in patients receiving a hematopoietic stem cell transplantation, and there were even fewer relapse-related deaths in the AML allo-HSCT cohort.

Persistent Systemic Microbial Translocation, Inflammation, and Intestinal Damage During Clostridioides difficile Infection

BACKGROUND

Clostridioides difficile infection (CDI) might be complicated by the development of nosocomial bloodstream infection (n-BSI). Based on the hypothesis that alteration of the normal gut integrity is present during CDI, we evaluated markers of microbial translocation, inflammation, and intestinal damage in patients with CDI.

METHODS

Patients with documented CDI were enrolled in the study. For each subject, plasma samples were collected at T0 and T1 (before and after CDI therapy, respectively), and the following markers were evaluated: lipopolysaccharide-binding protein (LPB), EndoCab IgM, interleukin-6, intestinal fatty acid binding protein (I-FABP). Samples from nonhospitalized healthy controls were also included. The study population was divided into BSI+/BSI- and fecal microbiota transplantation (FMT) +/FMT- groups, according to the development of n-BSI and the receipt of FMT, respectively.

RESULTS

Overall, 45 subjects were included; 8 (17.7%) developed primary n-BSI. Markers of microbial translocation and intestinal damage significantly decreased between T0 and T1, however, without reaching values similar to controls (P < .0001). Compared with BSI-, a persistent high level of microbial translocation in the BSI+ group was observed. In the FMT+ group, markers of microbial translocation and inflammation at T1 tended to reach control values.

CONCLUSIONS

CDI is associated with high levels of microbial translocation, inflammation, and intestinal damage, which are still present at clinical resolution of CDI. The role of residual mucosal perturbation and persistence of intestinal cell damage in the development of n-BSI following CDI, as well as the possible effect of FMT in the restoration of mucosal integrity, should be further investigated.

Clostridioides difficile colonization and infection in patients admitted for a first autologous transplantation: Incidence, risk factors, and patient outcomes

BACKGROUND

More data are needed regarding the incidence, risk factors, and outcomes for Clostridioides difficile infection (CDI) and colonization in patients undergoing an autologous hematopoietic stem cell transplantation (AHSCT).

METHODS

We studied 472 consecutive patients admitted for a first AHSCT and conducted a prospective C difficile stool surveillance and ribotyping analysis in a subset of 94 patients.

RESULTS

Clostridioides difficile infection was diagnosed in 7% of patients for an incidence of 3.4 CDI/1000 inpatient days, recurrent/reinfection CDI was rare. CDI was increased in patients who were colonized on admission, had required a recent pre-admission inpatient stay for fever and/or serious infection, or received empiric therapy with a carbapenem or extended-spectrum penicillin. CDI was associated with a longer length of stay and higher hospital costs. Twelve of 94 patients (13%) were found to have colonization on admission; CDI was diagnosed in 27% of these vs 1% in those with initial negative stools. Colonization in the hospital for those negative on admission was infrequent. C difficile ribotyping showed a predominance of 014/020.

CONCLUSIONS

Clostridioides difficile infection is a significant infection in patients receiving a first AHSCT. The risk factors identified may be useful in designing preventive interventions.

The direct and indirect effects of vancomycin-resistant enterococci colonization in liver transplant candidates and recipients

Introduction: Vancomycin-resistant enterococci (VRE) colonization and subsequent infection results in increased morbidity, mortality and use of health-care resources. The burden of VRE colonization in liver transplant candidates and recipients is significant. VRE colonization is a marker of gut dysbiosis and its impact on the microbiota-liver axis, may negatively affect graft function and result in negative outcomes pre- and post-transplantation. Areas covered: In this article we describe the epidemiology of VRE colonization, risk factors for VRE infection, health-care costs associated with VRE, with a focus on the impact of VRE colonization on liver transplant recipients' fecal microbiota, the therapeutic strategies for VRE decolonization and proposed pathophysiologic mechanisms of VRE colonization in liver transplant recipients. Expert opinion: VRE colonization results in a significant loss of bacterial microbiome diversity. This may have metabolic consequences, with low production of short-chain fatty acids which may, in turn, result in immune dysregulation. As antibiotics have failed to decolonize the gut, alternative strategies such as fecal microbiota transplantation (FMT), stimulation of intestinal antimicrobial peptides and phage therapy warrants future studies.

Clostridioides difficile colonization and infection in patients with newly diagnosed acute leukemia: Incidence, risk factors, and patient outcomes

BACKGROUND

The frequency, risk factors, and outcomes for Clostridioides difficile infection (CDI) in patients with newly diagnosed acute leukemia (AL) admitted for induction therapy are unclear.

METHODS

We studied 509 consecutive patients with AL admitted between 2006 and 2017 and conducted a prospective C difficile surveillance and ribotyping analysis in a subset of these.

RESULTS

The incidence of CDI was 2.2/1,000 inpatient days during induction, and CDI was rare after discharge. CDI was highest in patients with acute myelogenous leukemia. A hospitalization shortly before admission and administration of a greater number of antibiotics increased the risk for CDI. No single class of antibiotics conveyed an increased risk. All cases were successfully treated, and CDI was not associated with an increase in length of stay, costs, or mortality. In a subgroup analysis, 16% of patients with acute myelogenous leukemia and 4% with other leukemia types were colonized on admission. Colonization was associated with a higher risk of CDI. Ribotyping of available isolates showed 27 different strain types with 014/020 and 027 being the most frequent.

CONCLUSIONS

The number of antibiotics administered are a major risk factor for CDI in patients with AL. However, CDI appears to have minimal clinical impact in this population.

The role of zinc and nutritional immunity in Clostridium difficile infection

Clostridium difficile in one of the most commonly reported nosocomial pathogens worldwide. Beyond antibiotic use, little is known about the host, microbiota, and environmental factors that contribute to susceptibility to and severity of C. difficile infection (CDI). We recently observed that in a mouse model of CDI, excess dietary zinc (Zn) alters the gut microbiota and decreases resistance to CDI. Moreover, we determined that high levels of Zn exacerbate C. difficile-associated disease and calprotectin-mediated Zn limitation is an essential host response to infection. In this addendum, we discuss how these findings add to our understanding of CDI and consider the potential implications of excess metal intake on the microbiota and infection.

Repurposing ebselen for decolonization of vancomycin-resistant enterococci (VRE)

Enterococci represent one of the microbial world's most challenging enigmas. Colonization of the gastrointestinal tract (GIT) of high-risk/immunocompromised patients by enterococci exhibiting resistance to vancomycin (VRE) can lead to life-threating infections, including bloodstream infections and endocarditis. Decolonization of VRE from the GIT of high-risk patients represents an alternative method to suppress the risk of the infection. It could be considered as a preventative measure to protect against VRE infections in high-risk individuals. Though multiple agents (ramoplanin and bacitracin) have been evaluated clinically, no drugs are currently approved for use in VRE decolonization of the GIT. The present study evaluates ebselen, a clinical molecule, for use as a decolonizing agent against VRE. When evaluated against a broad array of enterococcal isolates in vitro, ebselen was found to be as potent as linezolid (minimum inhibitory concentration against 90% of clinical isolates tested was 2 μg/ml). Though VRE has a remarkable ability to develop resistance to antibacterial agents, no resistance to ebselen emerged after a clinical isolate of vancomycin-resistant E. faecium was serially-passaged with ebselen for 14 days. Against VRE biofilm, a virulence factor that enables the bacteria to colonize the gut, ebselen demonstrated the ability to both inhibit biofilm formation and disrupt mature biofilm. Furthermore, in a murine VRE colonization reduction model, ebselen proved as effective as ramoplanin in reducing the bacterial shedding and burden of VRE present in the fecal content (by > 99.99%), cecum, and ileum of mice. Based on the promising results obtained, ebselen warrants further investigation as a novel decolonizing agent to quell VRE infection.

Prediction of Bloodstream Infection Due to Vancomycin-Resistant Enterococcus in Patients Undergoing Leukemia Induction or Hematopoietic Stem-Cell Transplantation

Background.

Bloodstream infection (BSI) to due vancomycin-resistant Enterococcus (VRE) is an important complication of hematologic malignancy. Determining when to use empiric anti-VRE antibiotic therapy in this population remains a clinical challenge.

Methods.

A single-center cohort representing 664 admissions for induction or hematopoietic stem-cell transplant (HSCT) from 2006 to 2014 was selected. We derived a prediction score using risk factors for VRE BSI and evaluated the model's predictive performance by calculating it for each of 16232 BSI at-risk inpatient days.

Results.

VRE BSI incidence was 6.5% of admissions (2.7 VRE BSI per 1000 BSI at-risk days). Adjusted 1-year mortality and length of stay were significantly higher in patients with VRE BSI. VRE colonization (adjusted odds ratio [aOR] = 8.4; 95% confidence interval [CI] = 3.4-20.6; P < .0001), renal insufficiency (aOR = 2.4; 95% CI = 1.0-5.8; P = .046), aminoglycoside use (aOR = 4.7; 95% CI = 2.2-9.8; P < .0001), and antianaerobic antibiotic use (aOR = 2.8; 95% CI = 1.3-5.8; P = .007) correlated most closely with VRE BSI. A prediction model with optimal performance included these factors plus gastrointestinal disturbance, severe neutropenia, and prior beta-lactam antibiotic use. The score effectively risk-stratified patients (area under the receiver operating curve = 0.84; 95% CI = 0.79-0.89). At a threshold of ≥5 points, per day probability of VRE BSI was increased nearly 4-fold.

Conclusions.

This novel predictive score is based on risk factors reflecting a plausible pathophysiological model for VRE BSI in patients with hematological malignancy. Integrating VRE colonization status with risk factors for developing BSI is a promising method of guiding rational use of empiric anti-VRE antimicrobial therapy in patients with hematological malignancy. Validation of this novel predictive score is needed to confirm clinical utility.

Enterococci and Their Interactions with the Intestinal Microbiome

The Enterococcus genus comprises over 50 species that live as commensal bacteria in the gastrointestinal (GI) tracts of insects, birds, reptiles, and mammals. Named "entero" to emphasize their intestinal habitat, Enterococcus faecalis and Enterococcus faecium were first isolated in the early 1900s and are the most abundant species of this genus found in the human fecal microbiota. In the past 3 decades, enterococci have developed increased resistance to several classes of antibiotics and emerged as a prevalent causative agent of health care-related infections. In U.S. hospitals, antibiotic use has increased the transmission of multidrug-resistant enterococci. Antibiotic treatment depletes broad communities of commensal microbes from the GI tract, allowing resistant enterococci to densely colonize the gut. The reestablishment of a diverse intestinal microbiota is an emerging approach to combat infections caused by antibiotic-resistant bacteria in the GI tract. Because enterococci exist as commensals, modifying the intestinal microbiome to eliminate enterococcal clinical pathogens poses a challenge. To better understand how enterococci exist as both commensals and pathogens, in this article we discuss their clinical importance, antibiotic resistance, diversity in genomic composition and habitats, and interaction with the intestinal microbiome that may be used to prevent clinical infection.

Is Clostridium difficile infection a risk factor for subsequent bloodstream infection?

BACKGROUND

Clostridium difficile infection (CDI) is a common nosocomial diarrheal illness increasingly associated with mortality in United States. The underlying factors and mechanisms behind the recent increases in morbidity from CDI have not been fully elucidated. Murine models suggest a mucosal barrier breakdown leads to bacterial translocation and subsequent bloodstream infection (BSI). This study tests the hypothesis that CDI is associated with subsequent BSI in humans.

METHODS

We conducted a retrospective cohort study on 1132 inpatients hospitalized >72 h with available stool test results for toxigenic C. difficile. The primary outcome was BSI following CDI. Secondary outcomes included 30-day mortality, colectomy, readmission, and ICU admission. Unadjusted and adjusted logistic regression models were developed.

RESULTS

CDI occurred in 570 of 1132 patients (50.4%). BSI occurred in 86 (7.6%) patients. Enterococcus (14%) and Klebsiella (14%) species were the most common organisms. Patients with BSI had higher comorbidity scores and were more likely to be male, on immunosuppression, critically ill, and have a central venous catheter in place. Of the patients with BSI, 36 (42%) had CDI. CDI was not associated with subsequent BSI (OR 0.69; 95% CI 0.44-1.08; P = 0.103) in unadjusted analysis. In multivariable modeling, CDI appeared protective against subsequent BSI (OR 0.57; 95% CI 0.34-0.96; P = 0.036). Interaction modeling suggests a complicated relationship among CDI, BSI, antibiotic exposure, and central venous catheter use.

CONCLUSIONS

In this cohort of inpatients that underwent testing for CDI, CDI was not a risk factor for developing subsequent BSI.

Selected Topics in Anaerobic Bacteriology

Alteration in the host microbiome at skin and mucosal surfaces plays a role in the function of the immune system, and may predispose immunocompromised patients to infection. Because obligate anaerobes are the predominant type of bacteria present in humans at skin and mucosal surfaces, immunocompromised patients are at increased risk for serious invasive infection due to anaerobes. Laboratory approaches to the diagnosis of anaerobe infections that occur due to pyogenic, polymicrobial, or toxin-producing organisms are described. The clinical interpretation and limitations of anaerobe recovery from specimens, anaerobe-identification procedures, and antibiotic-susceptibility testing are outlined. Bacteriotherapy following analysis of disruption of the host microbiome has been effective for treatment of refractory or recurrent Clostridium difficile infection, and may become feasible for other conditions in the future.

Rising Vancomycin-Resistant Enterococcus Infections in Hospitalized Children in the United States

OBJECTIVE

Vancomycin-resistant Enterococcus (VRE) is an emerging drug-resistant organism responsible for increasing numbers of nosocomial infections in adults. Few data are available on the epidemiology and impact of VRE infections in children. We hypothesized a significant increase in VRE infections among hospitalized children. Additionally, we predicted that VRE infection would be associated with certain comorbid conditions and increased duration and cost of hospitalization.

METHODS

A retrospective study of inpatient pediatric patients was performed using data on hospitalizations for VRE from the Healthcare Cost and Utilization Project Kids' Inpatient Database from 1997 to 2012. We used a multivariable logistic regression model to establish factors associated with VRE infection and a high-dimensional propensity score match to evaluate death, length of stay, and cost of hospitalization.

RESULTS

Hospitalizations for VRE infection showed an increasing trend, from 53 hospitalizations per million in 1997 to 120 in 2012 (P < .001). Conditions associated with VRE included Clostridium difficile infection and other diagnoses involving immunosuppression and significant antibiotic and health care exposure. Patients with VRE infection had a significantly longer length of stay (attributable difference [AD] 2.1 days, P < .001) and higher hospitalization costs (AD $8233, P = .004). VRE infection was not associated with an increased risk of death (odds ratio 1.03; 95% confidence interval 0.73-1.47).

CONCLUSIONS

VRE infections among hospitalized children are increasing at a substantial rate. This study demonstrates the significant impact of VRE on the health of pediatric patients and highlights the importance of strict adherence to existing infection control policies and VRE surveillance in certain high-risk pediatric populations.

Impact of vancomycin-resistant enterococci colonization in critically ill pediatric patients

BACKGROUND

We aimed to determine the frequency of vancomycin-resistant enterococci (VRE) infection occurrence in previously VRE-colonized children in a pediatric intensive care unit (PICU) and to identify associated risk factors.

METHODS

Infection control nurses have performed prospective surveillance of health care-associated infections and rectal VRE carriage in PICUs from January 2010-December 2014. This database was reviewed to obtain information about VRE-colonized and subsequently infected patients. A case-control study was performed to identify risk factors associated with VRE infection development in previously VRE-colonized patients.

RESULTS

Out of 1,134 patients admitted to the PICU, 108 (9.5%) were found to be colonized with VRE throughout the study period. Systemic VRE infections developed in 11 VRE-colonized patients (10.2%), and these included primary bloodstream infection (n = 6), urinary tract infection (n = 3), meningitis and bloodstream infection (n = 1), and meningitis (n = 1). Logistic regression analysis indicated long hospital stay (≥30 days) and glycopeptide use after detection of VRE colonization as risk factors for developing VRE infection in VRE-colonized patients (odds ratio [OR], 5.76; 95% confidence interval [CI], 1.6-15.8; P = .017 and OR, 12.8; 95% CI, 1.9-26.6; P = .012, respectively).

CONCLUSIONS

VRE colonization has important consequences in pediatric critically ill patients. Strict infection control measures should be implemented to prevent VRE colonization and thereby VRE infections. Furthermore, irrational antibiotic use and particularly glycopeptide use in VRE-colonized patients should be restricted.

A Cost-Benefit Analysis of Gown Use in Controlling Vancomycin-ResistantEnterococcusTransmission Is It Worth the Price?

Objective:

To determine the net benefit and costs associated with gown use in preventing transmission of van-comycin-resistantEnterococcus(VRE).

Design:

A cost-benefit analysis measuring the net benefit of gowns was performed. Benefits, defined as averted costs from reduced VRE colonization and infection, were estimated using a matched cohort study. Data sources included a step-down cost allocation system, hospital informatics, and microbiology databases.

Setting:

The medical intensive care unit (MICU) at Barnes-Jewish Hospital, St. Louis, Missouri.

Patients:

Patients admitted to the MICU for more than 24 hours from July 1, 1997, to December 31, 1999.

Interventions:

Alternating periods when all healthcare workers and visitors were required to wear gowns and gloves versus gloves alone on entry to the rooms of patients colonized or infected with VRE.

Results:

On base-case analysis, 58 VRE cases were averted with gown use during 18 months. The annual net benefit of the gown policy was $419,346 and the cost per case averted of VRE was $1,897. The analysis was most sensitive to the level of VRE transmission.

Conclusions:

Infection control policies (eg, gown use) initially increase the cost of health services delivery. However, such policies can be cost saving by averting nosocomial infections and the associated costs of treatment. The cost savings to the hospital plus the benefits to patients and their families of avoiding nosocomial infections make effective infection control policies a good investment.

Risk of Vancomycin-ResistantEnterococcus(VRE) Bloodstream Infection Among Patients Colonized With VRE

Background.

Colonization with vancomycin-resistantEnterococcus(VRE) is a risk factor for subsequent VRE bloodstream infection (BSI); however, risk factors for BSI among colonized patients have not been adequately described. We sought to determine the proportion of VRE-colonized patients who subsequently develop VRE BSI and to identify risk factors for VRE BSI among these patients.

Methods.

Records of 768 patients colonized with VRE from January 2002 through June 2005 were reviewed. The proportion of patients who developed VRE BSI was calculated, and the characteristics of these patients were compared, in a 2 : 1 ratio, with those of patients who did not develop VRE BSI. To identify risk factors for VRE BSI and for death, we used univariate logistic regression analysis and then multivariate logistic regression analysis. Using pulsed-field gel electrophoresis (PFGE), we compared the isolate recovered when the patient was colonized and the isolate recovered when the patient developed VRE BSI.

Results.

Of the 768 patients colonized with VRE, 31 (4.0%) developed VRE BSI. Multivariate analysis identified the following idependent risk factors for developing VRE BSI: infection of an additional body site other than blood (adjusted odds ratio [aOR], 3.9;P= .04), admission to the hospital from a long-term care facility (aOR, 12.6;P= .04), and receipt of vancomycin (aOR, 10.6;P< .001). The independent risk factors for death among patients colonized with VRE were immunosuppression (aOR, 12.9;P= .001 ) and VRE BSI (aOR, 9.1;P= .002). Of the 31 patients who developed VRE BSI, 23 (74%) had a pair of isolates representing VRE colonization and VRE BSI. For 19 (83%) of these 23 patients, the isolate representing BSI was genetically related to the isolate representing VRE colonization: 12 pairs of isolates (52%) had identical banding patterns, 5 had closely related patterns, and 2 had possibly related patterns.

Conclusion.

Of the 768 patients colonized with VRE, 31 (4.0%) usually developed VRE BSI due to a related strain. Independent risk factors for BSI among colonized patients were admission from a long-term care facility, infection of an additional body site, and exposure to vancomycin. Independent risk factors for death were immunosuppression and VRE BSI.

Risk of vancomycin-resistant enterococci bloodstream infection among patients colonized with vancomycin-resistant enterococci

Background

Vancomycin-resistant enterococci colonization has been reported to increase the risk of developing infections, including bloodstream infections.

Aim

In this study, we aimed to share our experience with the vancomycin-resistant enterococci bloodstream infections following gastrointestinal vancomycin-resistant enterococci colonization in pediatric population during a period of 18 months.

Method

A retrospective cohort of children admitted to a 400-bed tertiary teaching hospital in Izmir, Turkey whose vancomycin-resistant enterococci colonization was newly detected during routine surveillances for gastrointestinal vancomycin-resistant enterococci colonization during the period of January 2009 and December 2012 were included in this study. All vancomycin-resistant enterococci isolates found within 18 months after initial detection were evaluated for evidence of infection.

Findings

Two hundred and sixteen patients with vancomycin-resistant enterococci were included in the study. Vancomycin-resistant enterococci colonization was detected in 136 patients (62.3%) while they were hospitalized at intensive care units; while the remaining majority (33.0%) were hospitalized at hematology-oncology department. Vancomycin-resistant enterococci bacteremia was present only in three (1.55%) patients. All these patients were immunosuppressed due to human immunodeficiency virus (one patient) and intensive chemotherapy (two patients).

Conclusion

In conclusion, our study found that 1.55% of vancomycin-resistant enterococci-colonized children had developed vancomycin-resistant enterococci bloodstream infection among the pediatric intensive care unit and hematology/oncology patients; according to our findings, we suggest that immunosupression is the key point for developing vancomycin-resistant enterococci bloodstream infections.

Vancomycin-resistant enterococci colonization in patients with hematological malignancies: screening and its cost-effectiveness

BACKGROUND AND OBJECTIVE

We evaluated the rates of vancomycin-resistant enterococci (VRE) colonization and VRE-related bacteremia in patients with hematological malignancies in terms of routine screening culture and its cost-effectiveness.

MATERIALS AND METHODS

All patients of the hematology department who were older than 14 years of age and who developed at least one febrile neutropenia episode during chemotherapy for hematological cancers between November 2010 and November 2012 were evaluated retrospectively.

RESULTS

We retrospectively analyzed 282 febrile episodes in 126 neutropenic patients during a two-year study period. The study included 65 cases in the first study-year and 78 cases in the second study-year. The numbers of colonization days and colonized patient were748 days of colonization in 29 patients (44%) in the first study-year and 547 colonization days in 21 patients (26%) in the second study-year, respectively. Routine screening culture for VRE cost $4516,4 (427 cultures) in the first study-year, $5082,7 (504 cultures) in the second study-year depending on the number of patients and their length of stay.

CONCLUSION

In line with our study results, routine screening of hematological patients for VRE colonization is not costeffective. Routine surveillance culture for VRE should be considered with respect to the conditions of health care setting.

Enterococci and Their Interactions with the Intestinal Microbiome

The Enterococcus genus comprises over 50 species that live as commensal bacteria in the gastrointestinal (GI) tracts of insects, birds, reptiles, and mammals. Named "entero" to emphasize their intestinal habitat, Enterococcus faecalis and Enterococcus faecium were first isolated in the early 1900s and are the most abundant species of this genus found in the human fecal microbiota. In the past 3 decades, enterococci have developed increased resistance to several classes of antibiotics and emerged as a prevalent causative agent of health care-related infections. In U.S. hospitals, antibiotic use has increased the transmission of multidrug-resistant enterococci. Antibiotic treatment depletes broad communities of commensal microbes from the GI tract, allowing resistant enterococci to densely colonize the gut. The reestablishment of a diverse intestinal microbiota is an emerging approach to combat infections caused by antibiotic-resistant bacteria in the GI tract. Because enterococci exist as commensals, modifying the intestinal microbiome to eliminate enterococcal clinical pathogens poses a challenge. To better understand how enterococci exist as both commensals and pathogens, in this article we discuss their clinical importance, antibiotic resistance, diversity in genomic composition and habitats, and interaction with the intestinal microbiome that may be used to prevent clinical infection.

Case-case-control study on factors associated with vanB vancomycin-resistant and vancomycin-susceptible enterococcal bacteraemia

Background

Enterococci are a major cause of healthcare-associated infection. In Australia, vanB vancomycin-resistant enterococci (VRE) is the predominant genotype. There are limited data on the factors linked to vanB VRE bacteraemia. This study aimed to identify factors associated with vanB VRE bacteraemia, and compare them with those for vancomycin-susceptible enterococci (VSE) bacteraemia.

Methods

A case-case-control study was performed in two tertiary public hospitals in Victoria, Australia. VRE and VSE bacteraemia cases were compared with controls without evidence of enterococcal bacteraemia, but may have had infections due to other pathogens.

Results

All VRE isolates had vanB genotype. Factors associated with vanB VRE bacteraemia were urinary catheter use within the last 30 days (OR 2.86, 95% CI 1.09-7.53), an increase in duration of metronidazole therapy (OR 1.65, 95% CI 1.17-2.33), and a higher Chronic Disease Score specific for VRE (OR 1.70, 95% CI 1.05-2.77). Factors linked to VSE bacteraemia were a history of gastrointestinal disease (OR 2.29, 95% CI 1.05-4.99) and an increase in duration of metronidazole therapy (OR 1.23, 95% CI 1.02-1.48). Admission into the haematology/oncology unit was associated with lower odds of VSE bacteraemia (OR 0.08, 95% CI 0.01-0.74).

Conclusions

This is the largest case-case-control study involving vanB VRE bacteraemia. Factors associated with the development of vanB VRE bacteraemia were different to those of VSE bacteraemia.

The intestinal microbiota and susceptibility to infection in immunocompromised patients

PURPOSE OF REVIEW

Many infections of immunocompromised patients originate from the gastrointestinal tract. The pathogenesis of these infections often begins with alteration of the intestinal microbiota. Understanding the microbiota and how it can either cause or prevent infection is vital for the development of more effective prevention and treatment of these infections. This article reviews and discusses recent work providing insight into the intestinal microbiota of these at-risk immunocompromised patients.

RECENT FINDINGS

Studies continue to support the premise that commensal bacteria, largely anaerobic, serve to maintain microbial stability and colonization resistance by preventing overgrowth or domination with more pathogenic bacteria, through interactions within the microbial community and with the host. In patients with immune suppression due to high-dose chemotherapy or hematopoietic stem cell transplantation, disruption of the microbiota through antibiotics as well as impairment of host immunity gives rise to perturbations favoring intestinal domination by pathogenic species, leading to increased bacterial translocation and susceptibility to systemic infection.

SUMMARY

An understanding of the intestinal microbiota and the impact of antibiotics will help to guide our treatment of these gut-originating infections.

Clostridium difficile infection in pediatric acute myeloid leukemia: from the Canadian Infections in Acute Myeloid Leukemia Research Group

BACKGROUND

The prevalence and severity of Clostridium difficile infection (CDI) has increased over time in adult patients, but little is known about CDI in pediatric cancer. The primary objectives were to describe the incidence and characteristics of CDI in children with de novo acute myeloid leukemia (AML). The secondary objective was to describe factors associated with CDI.

METHOD

We performed a multicenter, retrospective cohort study of children with de novo AML and evaluated CDI. Recurrence, sepsis and infection-related death were examined. Factors associated with CDI were also evaluated.

RESULTS

Forty-three CDI occurred in 37 of 341 (10.9%) patients during 42 of 1277 (3.3%) courses of chemotherapy. There were 6 children with multiple episodes of CDI. Three infections were associated with sepsis, and no children died of CDI. Only 2 children had an associated enterocolitis. Both days of broad-spectrum antibiotics (odds ratio 1.03, 95% confidence interval: 1.01 to 1.06; P = 0.003) and at least 1 microbiologically documented sterile site infection (odds ratio 10.81, 95% confidence interval: 5.88 to 19.89; P < 0.0001) were independently associated with CDI.

CONCLUSIONS

CDI occurred in 11% of children receiving intensive chemotherapy for AML, and outcomes were not severe. CDI is not a prominent issue in pediatric AML in terms of prevalence, incidence or associated outcomes.

Changing epidemiology of Clostridium difficile-associated disease during stem cell transplantation

The incidence and severity of Clostridium difficile-associated disease (CDAD) within the general population has risen dramatically over the past decade, yet little data are available from hematopoietic stem cell transplantation (HSCT) centers. In the present study, we performed a chart review of 822 consecutive autologous and allogeneic HCST recipients treated at Northwestern Memorial Hospital between 2004 and 2008 to determine the incidence of CDAD at our institution. Variables including age, sex, diagnosis, chemotherapy regimen, transplantation type, microbial colonization, coinfections, diet, antibiotic use, neutropenic fever, comorbid conditions, time to engraftment, growth factor administration, and occurrence of graft-versus-host disease were assessed as potential risk factors for the development of CDAD. Eighty-five CDAD cases (10.3%) were identified. Bivariate analysis revealed a significant association between CDAD and neutropenic fever, administration of a neutropenic diet, ciprofloxacin and aztreonam use and duration of therapy, vancomycin and aztreonam use and duration of therapy, receipt of an allogeneic transplantation, bacterial coinfection, and vancomycin-resistant Entereococcus faecium (VRE) colonization. Cox regression analysis identified the following as factors associated with the development of CDAD: age >60 years, allogeneic transplantation, and prior VRE colonization. Allogeneic recipients with CDAD experienced increased higher rates of grades II to IV gastrointestinal graft-versus-host disease and nonrelapse mortality. A risk stratification model was developed to identify HSCT recipients at different levels of risk. With an incidence >10%, CDAD is a significant infectious complication of stem cell transplantation.

Infections in patients with hematologic neoplasms and hematopoietic stem cell transplantation: neutropenia, humoral, and splenic defects

Infections are common in patients with hematologic neoplasms and following allogeneic hematopoietic transplantation. Neutropenia and defects in adaptive B-cell-mediated immunity and/or lack of splenic function predispose patients to a host of diverse and often serious infections. It is important to recognize that patients who undergo treatment for hematologic neoplasms may have mixed immune defects, and their vulnerability to infection may continue to change, in part as a reflection of the dynamic developments in the practice of oncology. The main obstacle in providing targeted, evidence-based antimicrobial treatment is the unpredictable results of even the new generation of diagnostic assays. A definite diagnosis for most end-organ opportunistic diseases requires tissue samples that are seldom available. Because immune defects may coexist, empirical therapy is directed toward a wide spectrum of pathogens. Real-time information about innate and adaptive immune functions and the role of acute and chronic phase molecules may improve target-specific therapy.

Bacteraemia from an unrecognized source (occult bacteraemia) occurring during Clostridium difficile infection

BACKGROUND

The purpose of this investigation was to determine if disruption of the colonic epithelium during Clostridium difficile infection (CDI) is associated with bacteraemia due to secondary bacterial invasion by enteric organisms.

METHODS

We reviewed the medical records of 505 randomly selected individuals from a database of patients who tested positive for C. difficile toxin and identified bacteraemias that occurred in 2 periods-the pre-CDI and post-CDI periods. Medical records were reviewed to determine a source for each case of bacteraemia. Staphylococcal bacteraemias were excluded from the analysis.

RESULTS

In the pre-CDI period, 28 of 505 (5.5%) patients had non-staphylococcal bacteraemia. A focus of infection was found in 24 of 28 (85.7%) cases. During CDI, 30 of 505 (5.9%) patients had non-staphylococcal bacteraemia; in the majority (19 cases, 63.3%) a focus of infection was not identified (p < 0.001). In the pre-CDI period, 16 of 28 (57.1%) blood cultures yielded Gram-negative pathogens compared to 9 of 30 (30%) in the CDI period (p = 0.04). Seven of 28 (25%) blood cultures in the pre-CDI period yielded enterococci compared to 15 of 30 (50%) in the CDI period (p = 0.05).

CONCLUSIONS

The incidence of non-staphylococcal bacteraemias in the pre- and post-CDI periods was nearly the same. Cases of bacteraemias in the CDI period more frequently involved organisms of unknown source and uncertain pathogenicity, and were usually not found to require antimicrobial therapy. The data favour the assumption that CDI-associated bacteraemia may be associated with bacterial invasion of the damaged colonic epithelium.

Prevalence of fecal carriage of antibiotic-resistant bacteria in patients with acute surgical abdominal infections

OBJECTIVE

Antibiotic resistance is increasing worldwide. The aims of the current study were to determine the fecal carriage of antibiotic-resistant bacteria and antibiotic treatment in surgical patients admitted to hospital due to acute intra-abdominal infections.

MATERIALS AND METHODS

Eight Swedish surgical units participated in this prospective multicenter investigation. Rectal swabs were obtained on admission to hospital. Cultures were performed on chromogenic agar and antibiotic susceptibility testing was performed using the disk diffusion method. Extended-spectrum beta-lactamase (ESBL)-phenotype was confirmed by Etest.

RESULTS

Rectal samples were obtained and analyzed from 208 patients with intra-abdominal surgical infections. Surgery was performed in 134 patients (65%). Cephalosporins were the most frequently used empirical antibiotic therapy. The highest rates of resistance among Enterobacteriaceae were detected for ampicillin (54%), tetracycline (26%), cefuroxime (26%) and trimethoprim-sulfamethoxazole (20%). The prevalence of decreased susceptibility (I + R) for the other antibiotics tested was for ciprofloxacin 20%, piperacillin-tazobactam 17%, cefotaxime 14%, ertapenem 12%, gentamicin 3% and imipenem 0%. ESBL-producing Enterobacteriaceae were found in samples from 10 patients (5%). Three patients had five E. coli isolates producing AmpC enzymes.

CONCLUSIONS

This study shows a high rate of resistance among Enterobacteriaceae against antibiotics which are commonly used in Sweden and should have implications for the future choice of antibiotics for surgical patients.

Clostridium difficile-associated disease in allogeneic hematopoietic stem-cell transplant recipients: risk associations, protective associations, and outcomes

The purpose of this study was to evaluate risk factors, protective factors, and outcomes associated with Clostridium difficile-associated disease (CDAD) in allogeneic hematopoietic stem-cell transplant (HSCT) recipients. A case-control study was performed with 37 CDAD cases and 67 controls. In the multivariable logistic regression analysis, receipt of a third or fourth generation cephalosporin was associated with increased risk of CDAD (OR = 4.6, 95% CI 1.6-13.1). Receipt of growth factors was associated with decreased risk of CDAD (OR=0.1, 95% CI 0.02-0.3). Cases were more likely to develop a blood stream infection after CDAD than were controls at any point before discharge (p < 0.001). CDAD cases were more likely than controls to develop new onset graft-vs.-host disease (GVHD) (p < 0.001), new onset severe GVHD (p < 0.001), or new onset gut GVHD (p = 0.007) after CDAD/discharge. Severe CDAD was a risk factor for death at 180 d in multivariable Cox proportional hazards regression (HR=2.6, 95% CI 1.1-6.2). CDAD is a significant cause of morbidity and mortality in allogeneic HSCT patients, but modifiable risk factors exist. Further study is needed to determine the best methods of decreasing patients' risk of CDAD.

Clostridium difficile-associated diarrhoea, a frequent complication in patients with acute myeloid leukaemia

Diarrhoea occurs frequently in neutropenic patients with acute leukaemia receiving chemotherapy and may be caused by either infection- or drug-induced cytotoxicity. Since Clostridium difficile is the most common cause of nosocomial infectious diarrhoea in non-haematologic patients, we were interested in its incidence in patients with acute myeloid leukaemia (AML). In this retrospective study, we analysed 134 patients with AML receiving a total of 301 chemotherapy courses. Diarrhoea occurred during 33% of all courses in 58 patients. C. difficile-associated diarrhoea (CDAD) occurred in 18% of all patients and 9% of all treatment courses. Almost one third of diarrhoea episodes were caused by C. difficile. CDAD was associated with older age (58 vs. 50 years), number of antibiotics administered (2 vs. 1), duration of antibiotic therapy (7 vs. 4 days), ceftazidime as the antibiotic of choice (75% vs. 54%) and duration of neutropenia (12 vs. 7 days) prior to onset of diarrhoea. An increased risk for CDAD was seen for prolonged neutropenia. CDAD responded well to oral metronidazole and/or vancomycin and no patient died of this complication. In conclusion, CDAD is common in patients with AML receiving chemotherapy. C. difficile enterotoxin testing of stool specimens should be included in all symptomatic patients.

Surveillance for vancomycin-resistant enterococci: type, rates, costs, and implications

OBJECTIVE

To evaluate 2 active surveillance strategies for detection of enteric vancomycin-resistant enterococci (VRE) in an intensive care unit (ICU).

DESIGN

Thirty-month prospective observational study.

SETTING

ICU at a university-affiliated referral center.

PATIENTS

All patients with an ICU stay of 24 hours or more were eligible for the study.

INTERVENTION

Clinical active surveillance (CAS), involving culture of a rectal swab specimen for detection of VRE, was performed on admission, weekly while the patient was in the ICU, and at discharge. Laboratory-based active surveillance (LAS), involving culture of a stool specimen for detection of VRE, was performed on stool samples submitted for Clostridium difficile toxin detection.

RESULTS

Enteric colonization with VRE was detected in 309 (17%) of 1,872 patients. The CAS method initially detected 280 (91%) of the 309 patients colonized with VRE, compared with 25 patients (8%) detected by LAS; colonization in 4 patients (1%) was initially detected by analysis of other clinical specimens. Most patients with colonization (76%) would have gone undetected by LAS alone, whereas use of the CAS method exclusively would have missed only 3 patients (1%) who were colonized. CAS cost Dollars 1,913 per month, or Dollars 57,395 for the 30-month study period. Cost savings of CAS from preventing cases of VRE colonization and bacteremia were estimated to range from Dollars 56,258 to Dollars 303,334 per month.

CONCLUSIONS

A patient-based CAS strategy for detection of enteric colonization with VRE was superior to LAS. In this high-risk setting, CAS appeared to be the most efficient and cost-effective surveillance method. The modest costs of CAS were offset by the averted costs associated with the prevention of VRE colonization and bacteremia.

Rectal colonization and frequency of enterococcal cross-transmission among prolonged-stay patients in two Swedish intensive care units

The aims of this study were to gain insight into the dynamics of the rectal flora during prolonged ICU stay, with a particular focus on colonization and cross-transmission with resistant pathogens, and to evaluate methods for the rapid isolation of relevant bacteria from rectal swabs. Patients admitted to a general intensive care unit (GICU) or a cardiothoracic ICU (TICU) at the University Hospital of Linköping, Sweden, between 1 November 2001 and January 2002 with a length of stay > 5 d were included (n = 20). Chromogenic UTI agar medium was used for discrimination of different species, and appropriate antibiotics were added to detect resistance. Direct plating was compared to enrichment broth for a subset of specimens. The study showed an early alteration in rectal flora, with a dramatic decrease in Gram-negative rods in favour of Gram-positive bacteria. An ampicillin- and high-level gentamicin resistant clone of Enterococcus faecium was found in 6 of 10 patients in the GICU and 2 of 11 patients in the TICU. Enrichment broth did not enhance the detection of Gram-negative bacteria compared to direct plating on Chromogenic UTI medium, but enrichment broths were needed for optimal detection of resistant Gram-positive bacteria.

Vancomycin-resistant enterococcal bacteremia in a hematology unit: molecular epidemiology and analysis of clinical course

An increase in vancomycin-resistant enterococcal (VRE) bacteremia in hemato-oncological patients (n=19) in our institution from 2000 through 2001 led us to analyze the molecular epidemiologic patterns and clinical features unique to our cases. The pulsed field gel electrophoresis of the isolates revealed that the bacteremia was not originated from a single clone but rather showed endemic pattern of diverse clones with small clusters. A different DNA pattern of blood and stool isolates from one patient suggested exogenous rather than endogenous route of infection. Enterococcus faecium carrying vanA gene was the causative pathogen in all cases. Patients with VRE bacteremia showed similar clinical courses compared with those with vancomycin-susceptible enterococcal (VSE) bacteremia. Vancomycin resistance did not seem to be a poor prognostic factor because of similar mortality (5/8, 62.5%) noted in VSE bacteremia. Initial disease severity and neutropenic status may be major determinants of prognosis in patients with VRE bacteraemia.

Vancomycin-resistant enterococci: a road map on how to prevent the emergence and transmission of antimicrobial resistance

Nosocomial acquisition of microorganisms resistant to multiple antibiotics represents a threat to patient safety. Here we review the mechanisms that have allowed highly resistant strains belonging to the Enterococcus genus to proliferate within our health-care institutions. These mechanisms indicate that decreasing the prevalence of resistant organisms requires active surveillance, adherence to vigorous isolation, hand hygiene and environmental decontamination measures, and effective antibiotic stewardship. We suggest how to tailor such a complex, multidisciplinary program to the needs of a particular health-care setting so as to maximize cost-effectiveness.

Clostridium difficile-associated diarrhea: epidemiological data from Western Australia associated with a modified antibiotic policy

The incidence of Clostridium difficile-associated diarrhea (CDAD) has increased dramatically in hospitals worldwide during the past 2 decades. In Western Australia, this increase was most obvious during the 1980s, when there was also an increase in the use of third-generation cephalosporin antibiotics. A study of the epidemiology of CDAD and the use of third-generation cephalosporins during 1993-2000 was undertaken. From 1993 through 1998, the incidence of CDAD remained relatively stable (2-3 cases per 1000 discharges annually). Then, a significant decrease in the incidence occurred, from 2.09 cases per 1000 discharges (95% confidence interval [CI], 1.71-2.47) in 1998 to 0.87 cases per 1000 discharges (95% CI, 0.63-1.11) in 1999 (P<.0001); this decrease persisted into 2000. A decrease in third-generation cephalosporin use occurred during the period of the study because of changes in the prescribing policy. These findings suggest that a reduction in the use of third-generation cephalosporins can reduce the occurrence of CDAD.

Risk factors for development of vancomycin-resistant enterococcal bloodstream infection in patients with cancer who are colonized with vancomycin-resistant enterococci

Vancomycin-resistant Enterococcus faecium (VRE) is a common nosocomial isolate, especially among patients with cancer. VRE infections have substantial attributable mortality among patients with cancer. The purpose of this study was to identify risk factors for developing bloodstream infection with VRE in patients with cancer who are colonized with VRE. VRE colonization was prospectively identified in 197 patients with cancer during 4-year period, of whom 179 (91%) had complete records for evaluation. Of these 179 patients, 24 (13.4%) developed hospital-acquired VRE bloodstream infections. Risk factors for VRE bloodstream infection included vancomycin use (relative risk [RR], 1.98; 95% confidence interval [CI], 1.25-3.14), diabetes mellitus (RR, 3.91; 95% CI, 1.20-12.77), gastrointestinal procedures (RR, 4.56; 95% CI, 1.05-19.7), and acute renal failure (RR, 3.10; 95% CI, 1.07-8.93). Strategies for preventing VRE bloodstream infection in VRE-colonized patients with cancer should include limiting vancomycin use and, perhaps, gastrointestinal procedures.

Osteomyelitis attributable to vancomycin-resistant enterococci

Vancomycin-resistant enterococcus first was described in 1988, and has become a major problem in nosocomial infections. This is a retrospective review of 10 patients, seen at the authors' hospital during a 2-year period, with confirmed vancomycin-resistant enterococcal osteomyelitis: four patients had total joint arthroplasty infections, one patient had an infected tibial nail, three patients had infections associated with external fixators, and two patients had osteomyelitis of the femur. Four of the 10 patients had underlying medical illnesses (diabetes mellitus, systemic lupus erythematosus, human immunodeficiency virus infection); four of the 10 patients were intravenous drug users. Two patients had vancomycin-resistant enterococci on admission, and the other eight patients were admitted to the hospital for a mean of 21.3 days (range, 3-73 days) before vancomycin-resistant enterococci were identified in the bone. Eight of the 10 patients had monomicrobial infections with vancomycin-resistant enterococci. Patients were treated by surgical debridement, removal of hardware, and antibiotics (chloramphenicol in eight patients, quinupristin and dalfopristin (Synercid) in two patients). All patients initially improved with therapy, but one patient had a recurrence of vancomycin-resistant enterococcal osteomyelitis and died of bacteremia. Bone infections with vancomycin-resistant enterococcus still may be uncommon, but with time and selective antibiotic pressures, vancomycin-resistant enterococci may become a more prominent entity in orthopaedic infections.

Reassessment of Clostridium difficile susceptibility to metronidazole and vancomycin

Clostridium difficile is the most frequently identified enteric pathogen in patients with nosocomially acquired, antibiotic-associated diarrhea. The drugs most commonly used to treat diseases associated with C. difficile are metronidazole and vancomycin. Most clinical laboratories assume that all C. difficile isolates are susceptible to metronidazole and vancomycin. We report on the antimicrobial susceptibilities of 415 C. difficile isolates to metronidazole and vancomycin over an 8-year period (1993 to 2000). The overall rate of resistance to metronidazole at the critical breakpoint (16 microg/ml) was 6.3%. Although full resistance to vancomycin was not observed, the overall rate of intermediate resistance was 3.1%. One isolate had a combination of resistance to metronidazole and intermediate resistance to vancomycin. Rates of resistance to metronidazole and vancomycin were higher among isolates from human immunodeficiency virus-infected patients. Molecular typing methods proved the absence of clonality among the isolates with decreased susceptibilities to the antimicrobials tested.

In vitro activity of linezolid against Clostridium difficile

We examined the in vitro activity of linezolid against Clostridium difficile, including isolates with reduced susceptibility to metronidazole or vancomycin. The MIC at which 50% of the isolates were inhibited (MIC50) and MIC90 were 0.5 and 2 microg/ml, respectively (range, 0.03 to 4 microg/ml). MICs were always <or= 4 microg/ml, and thus, all isolates were considered susceptible.