Bacteraemia due to extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) in cancer patients: clinical features, risk factors, molecular epidemiology and outcome

Characterization of integrons among Escherichia coli in a region at high incidence of ESBL-EC

Objective : The aim of study was to investigate the distribution of the integrons in Escherichia coli (E. coli) isolates, and analyze the possible relationship between the antimicrobial resistance profiles and the integrons. Methods : The antimicrobial profiles of 376 E. coli strains were analysed by disk diffusion test. The integron genes and variable regions were detected by PCR. Some amplicons were sequenced to determine the gene cassettes style. Results : Of 376 isolates, 223 isolates (59.3%) were confirmed as ESBL-EC. Comparison to ESBL-negative E. coli, the high rates of resistance to the third and fourth generation of cephalosporins, penicillins and amikacin were found in ESBL-EC. Only class 1 was integron detected in the isolates, and the prevalence of it was 66.5%. It was commonly found in ESBL-EC (77.6%, 173/223), which was higher than that of ESBL-negative E. coli (50.3%, 77/153) (p<0.001). Six different genes cassettes were detected in this study and were classified into three groups: dfr17-aadA5, dfrA12-aadA2 and aacA4-CmlA1. Additionally, more than one gene array harboured in 13.9% isolates of ESBL-EC, while in 9.1% isolates of ESBL-negative E.coli. Conclusion : The high incidence of ESBL-EC with resistance to multiple antibiotics were detected in the isolates from Blood stream infection (BSI). More resistant gene cassettes in ESBL-EC may partially underlie the high resistance to amikacin, while no relation exists between the high incidence of ESBL-EC and classes 1~ 3 integrons in this region.

Risk factors and molecular epidemiology of community-onset extended-spectrum β-lactamase-producing Escherichia coli bacteremia

PURPOSE

Inadequate empirical therapy for severe infections caused by extended-spectrum β-lactamase-producing Escherichia coli (ESBLEC) is associated with poor outcomes. This study was designed to investigate risk factors for community-onset ESBLEC bacteremia at admission to a tertiary care hospital.

MATERIALS AND METHODS

A case-control study was performed that included all episodes of ESBLEC bacteremia in the outpatient department or within 48 hours of admission from January 2005 to March 2009. Data on predisposing factors were collected. The molecular epidemiology of ESBLEC clinical isolates was also determined.

RESULTS

Among 25281 blood cultures, 60 episodes of ESBLEC bacteremia were studied, which accounted for 7% of all E. coli bacteremia at admission. Healthcare-associated infection [odds ratio (OR), 8.3; 95% confidence interval (CI), 2.4-28.7; p=0.001], malignancy (OR, 4.6; 95% CI, 1.3-16.3; p=0.018), urinary tract infection (OR, 139.1; 95% CI, 24.6-788.2; p<0.001), hepatobiliary infection (OR, 79.1; 95% CI, 13.5-463.8; p<0.001), third generation cephalosporin usage during preceding 3 months (OR, 16.4; 95% CI, 2.0-131.8; p=0.008), and severe sepsis/septic shock (OR, 73.7; 95% CI, 12.4-438.5; p<0.001) were determined as independent risk factors for community-onset ESBLEC bacteremia. The most common extended-spectrum β-lactamase (ESBL) gene identified was blaCTX-M-15 (n=31) followed by blaCTX-M-14 (n=23).

CONCLUSION

The most common types of ESBLs in E. coli causing community-onset bacteremia were CTX-M-15 and CTX-M-14 in Korea. By result of decision tree analysis, the empirical use of carbapenems is suggested only for patients with severe sepsis/septic shock, hepatobiliary infection, or healthcare-associated urinary tract infection.

Epidemiology of infections in cancer patients

Although major advances in the care of cancer patients over the past several decades have resulted in improved survival, infectious complications remain a significant cause of morbidity and mortality. To successfully identify, treat, and prevent infections, a comprehensive understanding of risk factors that predispose to infection and of commonly encountered pathogens is necessary. In addition, clinicians must keep abreast of the changing epidemiology of infections in this population. As therapeutic modalities continue to evolve, as established pathogens become increasingly drug resistant, and as new pathogens are discovered, successful management of infections will continue to present challenges in the years to come.

Multidrug-resistant bacteria: what is the threat?

Despite big advances in antimicrobial therapies and infection strategies, the emergence of antibiotic resistance represents an emergency situation, especially in immunocompromised hosts. Specifically, infections due to multidrug resistant, gram-negative pathogens are responsible for high mortality rates and may leave few effective antimicrobial options. Furthermore, although new compounds are available for severe methicillin-resistant staphylococcal infections, there is a paucity of novel classes of antimicrobials to target resistant gram-negatives. A careful assessment of the clinical conditions and underlying comorbidities, along with knowledge about the previous history of colonization or infections due to multidrug-resistant bacteria, represent key points in approaching the hematological patient with signs of infection. A de-escalation therapy with initial use of wide-spectrum antimicrobials followed by a reassessment after 72 hours of treatment may represent a good option in severe infections if a resistant pathogen is suspected. Prompt empiric or targeted therapy using combination regimens (ie, antipseudomonal beta-lactam plus an aminoglycoside or a quinolone) with the addition of colistin, along with increased dosage and therapeutic drug monitoring, represent options for these life-threatening infections. Continuous epidemiological surveillance of local bacteremias is necessary, along with stringent enforcement of antibiotic stewardship programs in cancer patients.

Relapsing bloodstream infections during treatment of acute leukemia

Acute leukemia (AL) patients may experience more than one episode of bloodstream infection (BSI) caused by the same pathogen during the entire chemotherapy program. In order to identify factors influencing BSI recurrence (R-BSI) during subsequent phases of treatment, we analyzed all BSIs occurring to consecutively treated AL patients during a period of active epidemiologic surveillance at our institution between 2004 and 2011. Two hundred and fifty BSIs were observed in 138 patients receiving more than 1 cycle of chemotherapy. BSI due to the same pathogen recurred in 39/138 (28.3 %) patients. Gram-negative rods (GNRs) accounted for 59.6 % and Gram-positive cocci (GPCs) for 34.4 % of BSI. Four pathogens were involved in R-BSI: Escherichia coli, Pseudomonas aeruginosa, coagulase-negative staphylococci, and Streptococcus viridans. GNRs were significantly more frequent among R-BSI compared to non-relapsing BSI (nR-BSI) [69/94 (73.4 %) vs 70/156 (50.6 %), p < 0.0001]; in particular, E. coli accounted for 67 % of R-BSI vs 32.1 % of nR-BSI (p < 0.0001). Receiving more than four chemotherapy courses and having an extended spectrum β-lactamase (ESBL)-producing E. coli BSI at any time of treatment were significantly associated to R-BSI. A trend toward a higher mortality among R-BSI patients in comparison with nR-BSI was observed (17.9 and 7.1 %, respectively, p = 0.12). Among AL patients, R-BSI is a frequent phenomenon, which may contribute to the shift of epidemiology toward GNR and to a higher mortality. This should significantly impact the strategies of antibiotic prophylaxis and treatment in patients with AL.

Increase in bloodstream infection due to vancomycin-susceptible Enterococcus faecium in cancer patients: risk factors, molecular epidemiology and outcomes

We conducted a prospective study to assess the risk factors, molecular epidemiology and outcome of bloodstream infection (BSI) due to Enterococcus faecium in hospitalized cancer patients. Between 2006 and 2012, a significant increase in vancomycin-susceptible E. faecium BSI was observed among cancer patients. Comparison of 54 episodes of BSI due to E. faecium with 38 episodes of BSI due to E. faecalis showed that previous use of carbapenems was the only independent risk factor for E. faecium acquisition (OR 10.24; 95% CI, 1.35-77.66). All E. faecium isolates were susceptible to glycopeptides, whereas 97% showed high-level resistance to ampicillin and ciprofloxacin. All 30 isolates available for genotyping belonged to the hospital-associated E. faecium lineages 17, 18 and 78. After 2009, most of the isolates belonged to ST117 (lineage 78). Patients with E. faecium BSI were more likely to receive inadequate initial empirical antibiotic therapy than patients with E. faecalis BSI, and time to adequate empirical antibiotic therapy was also longer in the former group. No significant differences were found between the two groups regarding early and overall case-fatality rates. Independent risk factors for overall case-fatality were current corticosteroids (OR 4.18; 95% CI, 1.34-13.01) and intensive care unit admission (OR 9.97; 95% CI, 1.96-50.63). The emergence of E. faecium among cancer patients is a concern since there are limited treatment options and it may presage the emergence of vancomycin-resistant enterococci. A rationale approach that combines infection control with antimicrobial stewardship.

Epidemiology and clinical outcomes of bloodstream infections caused by extended-spectrum β-lactamase-producing Escherichia coli in patients with cancer

Patients with cancer can be vulnerable to infection with antimicrobial-resistant pathogens such as extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. A cohort study was performed to evaluate the epidemiology and impact of ESBL-producing Escherichia coli (ESBL-EC) bacteraemia on the outcomes of adult patients with cancer. During the 2.5-year study period, a total of 350 cases of E. coli bacteraemia were documented in cancer patients, of which 95 (27.1%) were due to ESBL-EC. Significant factors associated with ESBL-EC bacteraemia were liver disease, immunosuppressant use, recent surgery, and prior use of cephalosporins or fluoroquinolones. The overall 30-day mortality rate was 14.9% (52/350), and the mortality rate was higher in patients with ESBL-EC than in those without ESBL-EC (22.1% vs.12.2%; P=0.02). Multivariate analysis showed that ESBL-EC was an independent risk factor for mortality (odds ratio=3.01, 95% confidence interval 1.45-6.28; P=0.003), along with the presence of septic shock, mechanical ventilation, the severity of underlying diseases, and pneumonia as a source of bacteraemia. Of the 69 isolates in which ESBLs and their molecular relationships were studied, 68 (98.6%) produced CTX-M-type and 51 (73.9%) produced CTX-M-14 and/or CTX-M-15. Twenty-four sequence types (STs) were identified among CTX-M-14- and CTX-M-15-producing E. coli isolates, with ST131 being the most prevalent (12/51; 23.5%). In conclusion, this study confirms that CTX-M-producing E. coli and ST131, which have been shown to be an emerging public health threat, are widely prevalent in cancer patients and can adversely affect the outcome of E. coli bacteraemia in these patients.

Colistin is relatively safe in hematological malignancies and hematopoietic stem cell transplantation patients

PURPOSE

Colistin is increasingly used as the last-resort treatment option against infections caused by multidrug-resistant (MDR) Gram-negative pathogens, but its nephrotoxicity is of concern, especially in severely ill patients. The aim of this study was to analyze the toxicity of colistin therapy in adults and children with hematological malignancies (HM) and hematopoietic stem cell transplantation (HSCT) recipients.

METHODS

Data on HSCT recipients and HM patients, treated with intravenous colistin (2.5-5 mg/kg/day in children and 3-6 million international units (IU) in adults, adjusted to renal function) during the period 2008-2011 in our center, were retrospectively collected and analyzed. Nephrotoxicity was defined according to the RIFLE criteria (Risk, Injury, Failure, Loss, and End-stage kidney disease).

RESULTS

Twenty-nine children and adults received 38 courses of intravenous colistin (2.5-5 mg/kg/day in children and 3-6 × 10(6) IU in adults, adjusted to renal function) [allogeneic HSCT (22 courses) and HM (16 courses)] for 3-28 days (median 10 days) for empirical therapy for nosocomial clinical sepsis (28) or local infection (6), and bacteremia with MDR Gram-negative rods (4). Nephrotoxicity was observed at the end of 4 (10.5%) courses. In 32 (84%) courses, nephrotoxic medications were concomitantly administered. Two patients had convulsions, probably unrelated to colistin. Seven patients (18%) died while on colistin therapy. No death was attributed to an adverse effect of colistin.

CONCLUSIONS

Treatment with intravenous colistin, with dosage adjusted to renal function, was relatively safe for HM/HSCT patients, even with concomitantly administered nephrotoxic medications. Concern about nephrotoxicity should not justify a delay in initiating empirical colistin treatment in situations where infection with MDR Gram-negative rods is likely.

Positive culture for extended-spectrum β-lactamase during acute prostatitis after prostate biopsy is a risk factor for progression to chronic prostatitis

OBJECTIVE

To analyze whether strains positive for extended-spectrum β-lactamase (ESBL) affected the clinical course and progression to chronic prostatitis in patients with postbiopsy acute prostatitis.

METHODS

From 2002 to 2011, 3657 patients underwent transrectal ultrasound-guided biopsy of the prostate, and 33 patients with acute prostatitis were enrolled. Acute prostatitis was defined as a fever greater than 38°C, pyuria, and tenderness on digital rectal examination. Urine and blood cultures were tested for antibiotic susceptibility. Laboratory and clinical variables according to the presence of ESBL were analyzed.

RESULTS

Blood or urine culture was positive in 23 patients. The most common strain was Escherichia coli. Sixteen patients showed ESBL-positive and 18 patients were quinolone-resistant. Thirteen of 16 patients with ESBL-positive strains showed quinolone resistance, and 13 of 18 patients with quinolone resistance were ESBL-positive (P = .621). Besides imipenem, all ESBL-positive patients were susceptible to amikacin and were highly susceptible to cefoxitin and amoxicillin/clavulanic acid. The prevalence of ESBL-positive strains has tended to increase since 2006. Patients with ESBL had higher peak fever, white blood cell count, absolute neutrophil count, and longer duration of fever and hospitalization. The progression rate to chronic prostatitis was significantly higher in ESBL-positive patients (4/16 vs 0/17, P = .044).

CONCLUSION

Since 2006, ESBL strains have been increasing, and the presence of ESBL showed more detrimental effects on the clinical course of the patients, resulting in a higher rate of progression to chronic prostatitis.

Factors influencing the early mortality in haematological malignancy patients with nosocomial Gram negative bacilli bacteraemia: a retrospective analysis of 154 cases

Background

The aim of this study is to assess the factors influencing the early mortality (7-day after index blood culture) in haematological malignancy patients with Gram negative bacilli (GNB) bacteraemia.

Methods

Infection control committee records were reviewed to identify the cases between March 2006 and June 2011. Only one bacteraemic episode per patient was included in the study.

Results

A total of 154 patients with GNB bacteraemia were identified. The early mortality rate was 19.5% (30 out of 154). Blood cultures revealed Enterobacteriacea in 120 patients (Escherichia coli; 86, Klebsiella spp.; 28, Enterobacter cloacea; 6) and glucose non-fermenting GNB in 34 patients (Pseudomonas aeruginosa; 15, Acinetobacter baumannii; 11, Stenotrophomonas maltophilia; 7, Burkholderia cepacia; 1). Forty (33.3%) out of 120 Enterobacteriaceae were extended spectrum beta-lactamase (ESBL) producers and 18 (52.9%) out of 34 glucose non-fermenting GNB were multidrug resistant. Carbapenems were administered as first line therapy in 139 out of 154 patients. In univariate analysis Pitt's bacteraemia score, presence of aplastic anaemia, bacteraemia caused by glucose non-fermentating GNB, inappropriate empirical antibacterial treatment, presence of severe sepsis or septic shock, unable to achieve microbiological cure, and intensive care unit (ICU) acquired bacteraemia were associated with mortality. Multivariate analysis showed ICU acquired bacteraemia (OR, 12.55; 95% CI, 2.34–67.38, p = 0.003) as an independent factor associated with early mortality.

Conclusion

Haematological malignancy patients who require ICU care are at high risk for early mortality related to GNB bacteraemia. Based on the local findings pointing out high rate of multidrug resistance, carbapenems combined with colistin seems to be a reasonable approach as empirical treatment of these patients. However, increasing carbapenem resistance rate is of concern.

Recent changes in bacteremia in patients with cancer: a systematic review of epidemiology and antibiotic resistance

Bacteremia remains a major cause of life-threatening complication in patients with cancer. Significant changes in the spectrum of microorganisms isolated from blood culture have been reported in cancer patients over the past years. The aim of our systematic review was to inventory the recent trends in epidemiology and antibiotic resistance of microorganisms causing bacteremia in cancer patients. Data for this review was identified by searches of Medline, Scopus and Cochrane Library for indexed articles and abstracts published in English since 2008. The principal search terms were: "antimicrobial resistance", "bacteremia", "bacterial epidemiology", "bloodstream infection", "cancer patients", "carbapenem resistance", "Escherichia coli resistance", "extended-spectrum β-lactamase producing E. coli", "febrile neutropenia", "fluoroquinolone resistance", "neutropenic cancer patient", "vancomycin-resistant Enterococcus", and "multidrug resistance". Boolean operators (NOT, AND, OR) were also used in succession to narrow and widen the search. Altogether, 27 articles were selected to be analyzed in the review. We found that Gram-negative bacteria were the most frequent pathogen isolated, particularly in studies with minimal use of antibiotic prophylaxis. Another important trend is the extensive emergence of antimicrobial-resistant strains associated with increased risk of morbidity, mortality and cost. This increasing incidence of antibiotic resistance has been reported in Gram-negative bacteria as well as in Gram-positive bacteria. This exhaustive review, reporting the recent findings in epidemiology and antibiotic resistance of bacteremia in cancer patients, highlights the necessity of local continuous surveillance of bacteremia and stringent enforcement of antibiotic stewardship programs in cancer patients.

Antibiotic rotation for febrile neutropenic patients with hematological malignancies: clinical significance of antibiotic heterogeneity

Background

Our unit adopted the single administration of cefepime as the initial treatment for febrile episodes in neutropenic patients with hematological malignancies. However, recently, cefepime-resistant gram-negative bacteremia, including those with extended-spectrum β-lactamase (ESBL)-producers, was frequently observed in these patients. Therefore, we instituted a rotation of primary antibiotics for febrile neutropenic patients in an attempt to control antibiotic resistance.

Methods

This prospective trial was performed from August 2008 through March 2011 at our unit. After a pre-intervention period, in which cefepime was used as the initial agent for febrile neutropenia, 4 primary antibiotics, namely, piperacillin-tazobactam, ciprofloxacin, meropenem, and cefepime, were rotated at 1-month intervals over 20 months. Blood and surveillance cultures were conducted for febrile episodes, in order to assess the etiology, the resistance pattern (particularly to cefepime), and the prognosis.

Results

In this trial, 219 patients were registered. A 65.9% reduction in the use of cefepime occurred after the antibiotic rotation. In the surveillance stool cultures, the detection rate of cefepime-resistant gram-negative isolates, of which ESBL-producers were predominant, declined significantly after the intervention (8.5 vs 0.9 episodes per 1000 patient days before and after intervention respectively, P<0.01). Interestingly, ESBL-related bacteremia was not detected after the initiation of the trial (1.7 vs 0.0 episodes per 1000 patient days before and after intervention respectively, P<0.01). Infection-related mortality was comparable between the 2 periods.

Conclusions

We implemented a monthly rotation of primary antibiotics for febrile neutropenic patients. An antibiotic heterogeneity strategy, mainly performed as a cycling regimen, would be useful for controlling antimicrobial resistance among patients treated for febrile neutropenia.

There should be no ESKAPE for febrile neutropenic cancer patients: the dearth of effective antibacterial drugs threatens anticancer efficacy

The success of modern anticancer treatment is a composite function of enhanced efficacy of surgical, radiation and systemic treatment strategies and of our collective clinical abilities in supporting patients through the perils of their cancer journeys. Despite the widespread availability of antibacterial therapies, the threat of community- or healthcare facility-acquired bacterial infection remains a constant risk to patients during this journey. The rising prevalence of colonization by multidrug-resistant (MDR) bacteria in the population, acquired through exposure from endemic environments, antimicrobial stewardship and infection prevention and control strategies notwithstanding, increases the likelihood that such organisms may be the cause of cancer treatment-related infection and the likelihood of antibacterial treatment failure. The high mortality associated with invasive MDR bacterial infection increases the likelihood that many patients may not survive long enough to reap the benefits of enhanced anticancer treatments, thus threatening the societal investment in the cancer journey. Since cancer care providers arguably no longer have, and are unlikely to have in the foreseeable future, the antibacterial tools to reliably rescue patients from harm's way, the difficult ethical debate over the risks and benefits of anticancer treatments must now be reopened.

Escherichia coli and Klebsiella pneumoniae bacteremia in patients with neutropenic fever: factors associated with extended-spectrum β-lactamase production and its impact on outcome

Escherichia coli and Klebsiella pneumoniae are main pathogens in neutropenic fever even if the proportion of Gram-positive cocci is increasing. Extended-spectrum β-lactamases (ESBL)-producing organisms are an emerging problem in nosocomial infection. Nevertheless, until now, information about risk factors for the acquisition and clinical outcomes of bacteremia due to ESBL-producing organisms is limited in neutropenic patients. From medical records collected between January 2007 and December 2008, we identified a total of 101 consecutive patients who developed bacteremia due to E. coli (n = 87) or K. pneumoniae (n = 14). Twenty-six (26 %) cases of bacteremia were caused by ESBL-producing organisms. A hospital stay of >2 weeks during the 3 months preceding bacteremia [adjusted odds ratio (OR), 5.887; 95 % confidence interval (CI), 1.572-22.041] and the use of broad-spectrum cephalosporins in the 4 weeks prior to bacteremia (adjusted OR, 6.186; 95 % CI, 1.616-23.683) were significantly related to the acquisition of ESBL. Twenty-four (92 %) of the ESBL-producing organisms were susceptible to either piperacillin-tazobactam or amikacin. Aminoglycosides (amikacin or isepamicin) were the main appropriate antimicrobial agents used against the ESBL-producing isolates during the initial empirical treatment (16/22, 73 %). However, the 30-day mortality rates for ESBL bacteremia and non-ESBL bacteremia were not significantly different (15 vs 5 %; p = 0.199). As alternatives to carbapenem, piperacillin-tazobactam plus amikacin or isepamicin combinations may be effective empirical therapeutic options for patients with neutropenic fever who are at high risk of developing bacteremia with ESBL-producing pathogens.

Carbapenems versus alternative antibiotics for the treatment of bacteraemia due to Enterobacteriaceae producing extended-spectrum β-lactamases: a systematic review and meta-analysis

OBJECTIVES

To study the comparative mortality associated with carbapenems and alternative antibiotics for the treatment of patients with extended-spectrum β-lactamase (ESBL)-positive Enterobacteriaceae bacteraemia.

METHODS

We searched systematically PubMed and Scopus databases for studies providing data for mortality among patients treated with carbapenems, β-lactam/β-lactamase inhibitor combinations (BL/BLIs) or non-BL/BLIs (mainly cephalosporins and fluoroquinolones), preferably as monotherapy. Studies focusing on patients of all ages with community- and healthcare-associated bacteraemia were eligible. Data were pooled using the technique of meta-analysis.

RESULTS

Twenty-one articles, studying 1584 patients, were included. Escherichia coli and Klebsiella pneumoniae were the most commonly studied bacteria. Delay in appropriate treatment up to 6 days was reported. Carbapenems were used mainly as definitive therapy. Carbapenems were associated with lower mortality than non- BL/BLIs for definitive [risk ratio (RR) 0.65, 95% CI 0.47-0.91] and empirical (RR 0.50, 95% CI 0.33-0.77) treatment. No statistically significant differences in mortality were found between carbapenems and BL/BLIs administered as definitive (RR 0.52, 95% 0.23-1.13) or empirical (RR 0.91, 95% CI 0.66-1.25) treatment. BL/BLIs were not associated with lower mortality than non-BL/BLIs administered either definitively (RR 1.59, 95% 0.83-3.06) or empirically (RR 0.82, 95% 0.48-1.41). Data regarding subgroups according to the setting, comorbidity and bacterial species could not be extracted.

CONCLUSIONS

Based on data from non-randomized studies, carbapenems may be considered the treatment of choice for empirical treatment of patients with ESBL-producing Enterobacteriaceae bacteraemia. The role of BL/BLIs should be further evaluated for definitive treatment. Further research should focus on faster identification of ESBL-positive pathogens and potential differences in the treatment of each bacterial species.

Clinical characteristics and prognostic factors of Acinetobacter nosocomialis bacteraemia in patients with solid tumours

The clinical characteristics and risk factors for 28-day mortality in 120 patients with solid tumours with Acinetobacter nosocomialis bacteraemia were retrospectively analysed. Eighty-one patients (67.5%) had advanced-stage cancer. Most of the bacteraemia (37.5%) did not have an identified source. The bacteraemia episodes developed at a median of 15 days after hospitalization, and most during a non-neutropenic period (97.5%). Although only half of the patients received appropriate antimicrobial therapy, the mortality was relatively low (11.7%). High Pitt bacteraemia score and receipt of chemotherapy within the month before bacteraemia onset were independently associated with 28-day mortality.

Molecular analysis and risk factors for Escherichia coli producing extended-spectrum β-lactamase bloodstream infection in hematological malignancies

INTRODUCTION

Patients with hematologic malignancies have greater risk-factors for primary bloodstream infections (BSI).

METHODS

From 2004-2009, we analyzed bacteremia caused by extended-spectrum beta-lactamase Escherichia coli (ESBL-EC) (n = 100) and we compared with bacteremia caused by cephalosporin-susceptible E. coli (n = 100) in patients with hematologic malignancies.

OBJECTIVE

To assess the clinical features, risk factors, and outcome of ESBL-EC BSI in patients with hematologic malignancies, and to study the molecular epidemiology of ESBL-EC isolates.

RESULTS

The main diagnosis was acute leukemia in 115 patients (57.5%). Death-related E. coli infection was significantly increased with ESBL-EC (34% vs. control group, 19%; p = 0.03). Treatment for BSI was considered appropriate in 64 patients with ESBL-EC (mean survival, 245 ± 345 days), and in 45 control patients this was 443 ± 613 (p = 0.03). In patients not receiving appropriate antimicrobial treatment, survival was significantly decreased in cases compared with controls (26 ± 122 vs. 276 ± 442; p = 0.001). Fifty six of the ESBL-EC isolates were characterized by molecular analysis: 47 (84%) expressed CTX-M-15, two (3.6%) SHV, and seven (12.5%) did not correspond to either of these two ESBL enzymes. No TLA-1 enzyme was detected.

CONCLUSIONS

Patients who had been previously hospitalized and who received cephalosporins during the previous month, have an increased risk of ESBL-EC bacteremia. Mortality was significantly increased in patients with ESBL-EC BSI. A polyclonal trend was detected, which reflects non-cross transmission of multiresistant E.coli isolates.

An outbreak of extended-spectrum β-lactamase-producing Klebsiella pneumoniae in a neonatal intensive care unit

We present a large outbreak of ESBL-producing Klebsiella pneumoniae in a neonatal intensive care unit that resulted in 31 colonized infants, 10 invasive infections, and 5 attributable deaths over a 5-month period. Although the source of infection was unknown, overcrowding and understaffing appeared to have been aggravating factors.

P. aeruginosa bloodstream infections among hematological patients: an old or new question?

Pseudomonas aeruginosa is a well-known cause of severe and potentially life-threatening infections among hematological patients. A prospective epidemiological surveillance program ongoing at our Hematology Unit revealed an increase over time of P. aeruginosa bloodstream infections (BSI). Their impact on outcome and antibiotic susceptibility was analyzed. BSI which consecutively occurred at our institution during a 70-month period were evaluated and correlated with type of pathogen, status of underlying disease, neutropenia, previous antibiotic therapy, resistance to antibiotics, and outcome. During the observation period, 441 BSI were recorded. Frequency of Gram-negative BSI was higher than that of other pathogens (57.3%). Overall, 66 P. aeruginosa BSI were recorded; 22 out of 66 were multiresistant (MR P. aeruginosa). Thirty-day mortality for all BSI was 11.3%; it was 27.3% for P. aeruginosa BSI and 36.4% for MR P. aeruginosa. At multivariate analysis, only active hematological disease and P. aeruginosa BSI were associated to an increased risk of death. For MR P. aeruginosa, BSI mortality was 83.3% vs. 18.8% when empiric therapy included or not an antibiotic with in vitro activity against P. aeruginosa (p=0.011). Together with active disease, the emergence of P. aeruginosa BSI, particularly if multiresistant, was responsible for an increased risk of death among hematological patients at our institution. In this scenario, reconsidering the type of combination antibiotic therapy to be used as empiric treatment of neutropenic fever was worthwhile.

β-Lactam/β-lactam inhibitor combinations for the treatment of bacteremia due to extended-spectrum β-lactamase-producing Escherichia coli: a post hoc analysis of prospective cohorts

BACKGROUND

Extended-spectrum ß-lactamase-producing Escherichia coli (ESBL-EC) is an important cause of invasive infections. Alternatives to carbapenems--considered the drugs of choice--are needed because of the emergence of carbapenemase-producing enterobacteria. The efficacy of ß-lactam/ß-lactam inhibitors (BLBLI) in such infections is controversial.

METHODS

The authors performed a post hoc analysis of patients with bloodstream infections due to ESBL-EC from 6 published prospective cohorts. Mortality and length of hospital stay in patients treated with an active BLBLI (amoxicillin-clavulanic acid [AMC] and piperacillin-tazobactam [PTZ]) or carbapenem were compared in 2 cohorts: the empirical therapy cohort (ETC) and the definitive therapy cohort (DTC). Confounding was controlled by multivariate analysis; for patients in the ETC, a propensity score for receiving carbapenem was also used.

RESULTS

The ETC included 103 patients (BLBLI, 72; carbapenem, 31), and the DTC included 174 (BLBLI, 54; carbapenem, 120). Mortality rates at day 30 for those treated with BLBLI versus carbapenems were 9.7% versus 19.4% for the ETC and 9.3% versus 16.7% for the DTC, respectively (P > .2, log-rank test). After adjustment for confounders, no association was found between either empirical therapy with BLBLI (adjusted hazard ratio [HR], 1.14; 95% confidence interval [CI], .29-4.40; P = .84) or definitive therapy (adjusted HR, 0.76; 95% CI, .28-2.07; P = .5) and increased mortality. Furthermore, BLBLI therapy, with respect to carbapenem, was not found to influence length of hospital stay.

CONCLUSIONS

These results suggest that AMC and PTZ are suitable alternatives to carbapenems for treating patients with bloodstream infections due to ESBL-EC if active in vitro and would be particularly useful as definitive therapy.

Emergence of extended-spectrum β-lactamase-producing escherichia coli as a cause of community-onset bacteremia in South Korea: risk factors and clinical outcomes

To define the risk factors and clinical outcomes of community-onset bacteremia caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBLEC), we analyzed 50 consecutive cases of community-onset bacteremia caused by ESBLEC at a secondary hospital in South Korea from 2005 to 2010. Risk factors were assessed by conducting a case-double control study in which cases were compared with (1) control patients with community-onset bacteremia due to non-ESBLEC, and (2) those with community-onset bacteremia not caused by E. coli. Clinical outcome was assessed among patients with community-onset E. coli bacteremia. Community-onset bacteremia due to ESBLEC accounted for 6.7% of all community-onset E. coli bacteremia. In addition, an increasing proportion of ESBLEC among patients without any healthcare risk factors was observed. Comparison with both control groups revealed that the recent use of antibiotics (odds ratio [OR], 4.3; 95% confidence interval [CI], 1.5-12.3) was an independent risk factor for ESBL acquisition. Factors influencing the 30-day mortality were a high Acute Physiology and Chronic Health Evaluation (APACHE) II score (OR, 1.5; 95% CI, 1.1-2.0) and severe sepsis or septic shock (OR, 26.6; 95% CI, 1.5-470.7) and malignancy (OR, 11.9; 95% CI, 1.1-134.8). Increased mortality was not statistically associated either with ESBL production or with inappropriate empirical therapy. ESBLEC has emerged as a significant cause of community-onset bacteremia in this hospital, suggesting that ESBLEC are widely disseminated in the South Korean community.

At least it won't hurt: the personal risks of antibiotic exposure

This review presents recent evidence regarding the adverse effects of antibiotic therapy mediated by collateral damage to commensal flora. Two major drivers have characterized recent research in this field: new perspectives into human microbiota afforded by next-generation DNA sequencing techniques and ongoing attention to antimicrobial resistance. New molecular techniques have illustrated that antibiotic therapy can disturb human microbiota, and that these changes are associated with infection. Concurrently, epidemiologic studies using patient-level data offer new insights into the role of antibiotics in the emergence, selection and spread of antimicrobial resistance, and Clostridium difficile infection (CDI).

Risk factors for infection and treatment outcome of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae bacteremia in patients with hematologic malignancy

This study was performed to evaluate the impact of extended-spectrum β-lactamase (ESBL)-producing bacteremia on outcome in patients with hematologic malignancy. We collected and analyzed data on 156 hematologic malignancy patients with Escherichia coli or Klebsiella pneumoniae bacteremia from the database of nationwide surveillance studies for bacteremia. Thirty-seven of the 156 patients (23.7%) harbored ESBL-producing bacteremia. No significant differences in underlying diseases were found in either group. The multivariate analysis showed that significant factors associated with ESBL-producing bacteremia were ICU care (OR = 7.03, 95% CI = 1.79-27.6) and nosocomial acquisition (OR = 5.66, 95% CI = 1.60-20.23). There was an association between prior receipt of cephalosporins and ESBL-producing bacteremia, although this association was not statistically significant (OR = 2.27, 95% CI = 0.99-5.23). The overall 30-day mortality rate of the study population was 20.4% (29/142), and the 30-day mortality rate for the ESBL group was significantly higher than that for the non-ESBL group (44.8% vs. 14.2%, P < 0.001). Multivariate analysis showed that ESBL-producing bacteremia was the most important risk factor associated with 30-day mortality (OR, 5.64; 95% CI, 1.91-16.67), along with ICU care (OR = 4.35, 95% CI = 1.16-16.26) and higher Pitt bacteremia score (per 1-point increment) (OR = 1.50, 95% CI = 1.18-1.92). In conclusion, ESBL-producing bacteremia was the most important risk factor associated with 30-day mortality in patients with hematologic malignancy, along with ICU care and higher Pitt bacteremia score. Our data suggest that determining the optimal empiric antimicrobial therapy in patients with hematologic malignancy is now becoming a challenge for clinicians in the era of multidrug-resistant Gram-negative bacilli.

Ten-year surveillance of nosocomial bloodstream infections: trends of aetiology and antimicrobial resistance in a comprehensive cancer centre

Background:

Bloodstream infections (BSIs) are one of the major life-threatening infectious conditions in cancer patients and are responsible for prolonged hospital stays, high healthcare costs and significant mortality. Several clinical trials have reported an improved survival in patients treated with appropriate empirical broad-spectrum antibiotic therapy. Early detection of pathogens and determination of their susceptibility are essential for the optimization of treatment. Variability between hospitals is substantial and requires the individual analysis of local trends. The aim of this study is to assess the local epidemiology of BSI in a single cancer centre over a 10-year period.

Methods:

Retrospective microbiological surveillance of all febrile/infective episodes occurring in oncological and surgical patients in a high-volume cancer centre between January 1999 and December 2008 were considered. Patients’ data were collected, processed and analyzed using the epidemiological resource of the Virtuoso Plus software (Metafora Informatica Srl, Milano, Italy). Spearman’s rank correlation coefficient, including the two-tailed test of significance, was used to investigate trends of incidence and rate of antibiotic resistance over the 10-year period.

Results:

A total of 13,058 blood cultures (BCs) were performed in 2,976 patients. BCs were positive in 2,447 tests, representing 740 infective/febrile episodes: 358 (48%) in medical oncology and 382 (52%) in surgical wards. Gram-positives were responsible for the majority of episodes in oncological and surgical divisions (about 63% and 55%, respectively). Gram-positives were also the most common organism in non-catheter-related BSIs (CRBSIs) both in medical oncology (75%) and in surgical divisions (50%). Enterococci showed an increased resistance to levofloxacin, from 5.6% to 25.7% (p = 0.02) and to erythromycin, from 41.7% to 61.4%, (p = 0.05). Similarly, coagulase negative staphylococci (CoNS) developed resistance to levofloxacin and ciprofloxacin, passing from 33.9% to 67.4% (p = 0.01) and from 5.6% to 25.7% (p = 0.01), respectively.

Conclusions:

Gram-positives are the main pathogens of BSIs; there is no difference in aetiology of CRBSIs between surgical and oncological patients. The lower incidence of gram-positive non-CRBSIs in surgical patients was probably due to gram-negative infections secondary to surgical complications.

Clinical manifestations and prognostic factors in cancer patients with bacteremia due to extended-spectrum β-lactamase-producing Escherichia coli or Klebsiella pneumoniae

BACKGROUND

Clinical information about bacteremia due to extended-spectrum β-lactamase (ESBL)-producing pathogens in cancer patients was limited. The study was aimed to identify the clinical manifestations and risk factors for mortality in ESBL-producer bacteremia in cancer patients.

METHODS

A retrospective study of bacteremia caused by ESBL-producing Escherichia coli or Klebsiella pneumoniae in adults with cancer in National Cheng Kung University Hospital and National Taiwan University Hospital from July 2002 to August 2007 was conducted. Clinical characteristics, initial manifestations, and antimicrobial therapy were analyzed for their association with crude mortality at 14 days after bacteremia onset.

RESULTS

A total 113 episodes of bacteremia caused by E coli (59.3%), K pneumoniae (39.8%) or both (0.9%) were included. Patients with hematological malignancy were younger (55 ± 22 vs. 69 ± 14 years, p < 0.003) and had less co-morbidity, but were more likely to have neutropenia (73.1% vs. 4.6%, p < 0.001) than those with solid tumor. By the univariate analysis in 113 episodes of ESBL-producer bacteremia, several risk factors, including pneumonia or soft-tissue infection as the bacteremia source, initial manifestations with high Pitt bacteremia scores, shock, respiratory failure or severe sepsis, and inappropriate definitive therapy were associated with 14-day crude mortality. By multivariate analysis, only pneumonia [adjusted odds ratio (AOR), 5.2; 95% confident interval (CI), 1.3-21.0; p = 0.021], severe sepsis (AOR, 24.3; 95% CI, 5.6-105.0; p < 0.001), and inappropriate definitive therapy (AOR, 11.3; 95% CI, 1.7-72.8; p = 0.011) were independently associated with a fatal outcome.

CONCLUSION

The presence of neutropenia or underlying hematological malignancy in cancer patients with ESBL-producer bacteremia was not associated with an increase in the mortality rate. Appropriate definitive antimicrobial therapy will be beneficial in improving clinical outcome.