Carbapenem therapy is associated with improved survival compared with piperacillin-tazobactam for patients with extended-spectrum β-lactamase bacteremia

Clinical and Microbiological Characteristics of Patients with Complicated Intra-abdominal Infections in Intensive Care Unit

In order to investigate the clinical and microbiological characteristics of patients with complicated intra-abdominal infections (cIAIs) in intensive care unit (ICU), the clinical data of 612 cIAIs patients from January 2016 to December 2018 were retrospectively collected. Clinical characteristics, distribution of pathogens and drug resistance were statistically analyzed. It was found that patients with community-acquired intra-abdominal infections (CA-IAIs) made up a majority of cIAIs patients. The positive rate of abdominal drainage fluid culture was 55.56%. Gramnegative bacteria accounted for the majority, the most commonly isolated bacteria of which were Escherichia coli (20.96%), Klebsiella pneumoniae (10.20%) and Pseudomonas aeruginosa (5.57%). The most commonly isolated gram-positive bacteria were Enterococcus (16.88%) and Methicillin-resistant staphylococcus aureus (MRSA, 3.90%). Enterobacter isolates showed high resistance rate to most cephalosporins and low resistance rate to piperacillin/tazobactam and carbapenems. Extended spectrum beta-lactamase (ESBL) screen positive isolates from CA-IAIs patients showed an increasing trend in past three years. Enterococcus and MRSA showed high resistance rate to clindamycin, quinolone, erythromycin and tetracycline, while they showed high sensitivity rate to linezolid, tegacycline, teicoplanin and vancomycin. Our results indicate that isolated bacteria from abdominal drainage fluid show high resistance rates to commonly used antibiotics in ICU patients with cIAIs. The curative effects on diseases should be monitored continuously when antibiotics are used. Meanwhile, we should always keep eyes on drug-resistant bacteria, especially when the treatment efficacy is not good.

Molecular Mechanisms and Epidemiology of Carbapenem-Resistant Escherichia coli Isolated from Chinese Patients During 2002-2017

Background

The emergence and spread of carbapenem-resistant Escherichia coli (E. coli) pose a serious threat to human health worldwide. This study aimed to investigate the molecular mechanisms underlying carbapenem resistance and their prevalence among E. coli in China.

Methods

A collection of 5796 E. coli clinical isolates were collected from the First Affiliated Hospital of Wenzhou Medical University from 2002 to 2017. Sensitivity to antibiotics was determined using the agar dilution method. The detection of carbapenemases production and the prevalence of resistance-associated genes were investigated through modified carbapenem inactivation method (mCIM), PCR and sequencing. The mutations in outer membrane porins genes (ompC and ompF) were also analyzed by PCR and sequencing assays. The effect of efflux pump mechanism on carbapenem resistance was also tested. E. coli were typed by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

Results

A total of 58 strains (1.0%) of carbapenem-resistant E. coli were identified. The strains carrying bla_KPC-2 and bla_NDM accounted for 22.4% (13/58) and 51.7% (30/58), respectively. Among bla_NDM- positive strains, 27 bla_NDM genes were assigned to bla_NDM-5, while the remaining three strains were bla_NDM-1, whereas bla_VIM, bla_IMP, bla_OXA-48, and bla_SHV were not found. The CTX-M-type β-lactamase genes accounted for 96.6% (56/58). In addition, bla_TEM-1 genes were identified in 58.6% of tested strains. In carbapenem-resistant isolates, mutations in OmpC (the majority of mutated sites were D192G and Q104_F141del, accounting for 54.5%) and OmpF (large deletions S75_V127del, W83_D135del and Q88_D135del) were detected. Of note, the antibiotic resistance was not associated with overexpression of efflux pump. Moreover, MLST categorized the 58 carbapenem-resistant isolates into 19 different sequence types. PFGE analysis revealed that homology among the carbapenem-resistant isolates was low and sporadic.

Conclusion

The bla_NDM was the principal resistance mechanism of carbapenem-resistant E. coli in the hospital. bla_NDM-5 is becoming a new threat to public health and the alteration of outer membrane porins might help further increase the MIC of carbapenem.

Carbapenem-Sparing Strategies for ESBL Producers: When and How

Extended spectrum β-lactamase (ESBL)-producing bacteria are prevalent worldwide and correlated with hospital infections, but they have been evolving as an increasing cause of community acquired infections. The spread of ESBL constitutes a major threat for public health, and infections with ESBL-producing organisms have been associated with poor outcomes. Established therapeutic options for severe infections caused by ESBL-producing organisms are considered the carbapenems. However, under the pressure of carbapenem overuse and the emergence of resistance, carbapenem-sparing strategies have been implemented. The administration of carbapenem-sparing antibiotics for the treatment of ESBL infections has yielded conflicting results. Herein, the current available knowledge regarding carbapenem-sparing strategies for ESBL producers is reviewed, and the optimal conditions for the "when and how" of carbapenem-sparing agents is discussed. An important point of the review focuses on piperacillin-tazobactam as the agent arousing the most debate. The most available data regarding non-carbapenem β-lactams (i.e., ceftolozane-tazobactam, ceftazidime-avibactam, temocillin, cephamycins and cefepime) are also thoroughly presented as well as non β-lactams (i.e., aminoglycosides, quinolones, tigecycline, eravacycline and fosfomycin).

Multicenter Evaluation of the New Etest Gradient Diffusion Method for Piperacillin-Tazobactam Susceptibility Testing of Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter baumannii Complex

Piperacillin-tazobactam (P/T) is a β-lactam-β-lactamase inhibitor combination frequently used in the hospital setting. Etest is a gradient diffusion method that represents an alternative to broth microdilution (BMD) for performing antimicrobial susceptibility testing. We conducted a multicenter evaluation of the performance of the new P/T Etest compared to that of BMD following U.S. Food and Drug Administration (FDA) and International Standards Organization (ISO) standard ISO 20776-2 criteria using Clinical and Laboratory Standards Institute (CLSI)-FDA and European Committee on Antimicrobial Susceptibility Testing (EUCAST) interpretive breakpoints, respectively. A total of 977 isolates (775 Enterobacterales isolates, 119 Pseudomonas aeruginosa isolates, and 83 Acinetobacter baumannii complex isolates) were tested. Overall essential agreement (EA) was 96.4% and 96.6% for Enterobacterales when FDA and ISO 20776-2 criteria, respectively, were followed. EA was 98.3% for P. aeruginosa and 91.6% for the A. baumannii complex when both the FDA and ISO criteria were followed. Applying CLSI-FDA breakpoints, categorical agreement (CA) reached 93.0%, 93.3%, and 89.2% for the Enterobacterales, P. aeruginosa, and the A. baumannii complex, respectively. Two very major errors (VMEs; 1.1%) were found among the Enterobacterales (for 2 Klebsiella pneumoniae isolates). No additional major errors (MEs) or VMEs were found. Applying EUCAST breakpoints, CA was 94.8% and 95.8% for Enterobacterales and P. aeruginosa, respectively (no breakpoints are currently available for the A. baumannii complex). No VMEs were observed among the Enterobacterales, but 2 (0.4%) MEs were found. Among the P. aeruginosa isolates, 2 (6.9%) VMEs and 3 (3.3%) MEs were observed. These errors resulted when P/T Etest MICs were 1 doubling dilution apart from the BMD MICs. In conclusion, the new P/T Etest represents an accurate tool for performing antimicrobial susceptibility testing of Enterobacterales, P. aeruginosa, and A. baumannii complex isolates with limited category errors.

Antimicrobial resistance of bacteraemia in the emergency department of a German university hospital (2013-2018): potential carbapenem-sparing empiric treatment options in light of the new EUCAST recommendations

Background

This study investigated predominant microorganisms causing community-onset bacteraemia at the medical emergency department (ED) of a tertiary-care university hospital in Germany from 2013 to 2018 and their antimicrobial susceptibility patterns.

Methods

Antimicrobial resistance patterns in patients with positive blood cultures presenting to an internal medicine ED were retrospectively analysed.

Results

Blood cultures were obtained at 5191 of 66,879 ED encounters, with 1013 (19.5%) positive results, and true positive results at 740 encounters (diagnostic yield, 14.3%). The most frequently isolated relevant microorganisms were Enterobacterales (n = 439, 59.3%), Staphylococcus aureus (n = 92, 12.4%), Streptococcus pneumoniae (n = 34, 4.6%), Pseudomonas aeruginosa (n = 32, 4.3%), Streptococcus pyogenes (n = 16, 2.2%), Enterococcus faecalis (n = 18, 2.4%), and Enterococcus faecium (n = 12, 1.6%). Antimicrobial susceptibility testing revealed a high proportion of resistance against ampicillin-sulbactam in Enterobacterales (42.2%). The rate of methicillin-resistant Staphylococcus aureus was low (0.4%).

Piperacillin-tazobactam therapy provided coverage for 83.2% of all relevant pathogens using conventional breakpoints. Application of the new European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations increased the percentage of susceptible isolates to high-dose piperacillin-tazobactam to 92.8% (p < 0.001). Broad-spectrum carbapenems would only cover an additional 4.8%. The addition of vancomycin or linezolid extended coverage by just 1.7%.

Conclusions

Using an ureidopenicillin-beta-lactamase inhibitor combination at the high dose suggested by the new EUCAST recommendations provided nearly 93% coverage for relevant pathogens in patients with suspected bloodstream infection in our cohort. This might offer a safe option to reduce the empiric use of carbapenems. Our data support the absence of a general need for glycopeptides or oxazolidinones in empiric treatment.

Colonization With Levofloxacin-resistant Extended-spectrum β-Lactamase-producing Enterobacteriaceae and Risk of Bacteremia in Hematopoietic Stem Cell Transplant Recipients

Background

Bacteremia caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) is associated with inadequate empirical therapy and substantial mortality in neutropenic patients. Strategies are needed to identify neutropenic patients at high risk of these infections.

Methods

From April 2014 to September 2016, we collected perianal swabs, both at admission and weekly thereafter, from patients undergoing hematopoietic stem cell transplantation (HSCT). Patients received prophylactic levofloxacin while neutropenic. Swabs were plated onto selective agar, colonies were identified and underwent antimicrobial susceptibility testing, and phenotypic ESBL testing and polymerase chain reaction for β-lactamase genes were performed on ceftriaxone-resistant Enterobacteriaceae. We then determined the prevalence of pre-transplant ESBL-E colonization and risk of ESBL-E bacteremia. Colonizing and bloodstream isolates from patients with ESBL-E bacteremia underwent multilocus sequence typing and pulsed-field gel electrophoresis.

Results

We analyzed 312 patients, including 212 allogeneic and 100 autologous HSCT recipients. Ten percent (31/312) of patients had pre-transplant ESBL-E colonization. Susceptibility rates of colonizing ESBL-E were: levofloxacin, 25%; cefepime, 9%; piperacillin-tazobactam, 84%; and meropenem, 97%. Of 31 patients colonized with ESBL-E pre-transplant, 10 (32%) developed ESBL-E bacteremia during their transplant admission, compared to 1 (0.4%) of 281 patients not colonized with ESBL-E (P < .001). All bloodstream ESBL-E were levofloxacin-resistant and colonizing and bloodstream isolates from individual patients had identical genotypic profiles.

Conclusions

HSCT recipients who are colonized with levofloxacin-resistant ESBL-E pre-transplant and receive levofloxacin prophylaxis have high rates of bacteremia from their colonizing strain during neutropenia. Assessing for ESBL-E colonization in neutropenic patients could lead to optimization of empirical antibacterial therapy.

Meropenem pharmacokinetics during relapsing peritonitis due to ESBL-producing Enterobacteriaciae in a liver transplant recipient

We report on an 8-year-old girl with Wilson disease who developed three episodes of peritonitis due to extended-spectrum beta-lactamase-producing Escherichia coli after liver transplantation. Massive ascites were thought to account for low meropenem concentrations with standard dosing. Extending the infusion achieved higher troughs, greater time above minimum inhibitory concentration.

Change in the Antimicrobial Resistance Profile of Extended-Spectrum β-Lactamase-Producing Escherichia coli

Background

This study aimed to investigate the trends and antimicrobial resistance profile of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) clinical isolates.

Methods

A total of 1,303 E. coli isolates from January 2012 to December 2017 at Fukuoka University Chikushi Hospital, Japan, were analyzed. The rate of resistance to cefmetazole (CMZ), flomoxef (FMOX), imipenem (IPM), meropenem (MEPM), amikacin (AMK), gentamicin (GM), minocycline (MINO), ciprofloxacin (CPFX), and levofloxacin (LVFX) was compared between non-ESBL-producing E. coli (non-ESBL-EC) and ESBL-EC.

Results

The proportion of ESBL-EC among all the E. coli isolates was 24.6% (320/1,303), and the proportion remained stable throughout the study period. There was no difference in the rate of resistance to CMZ, FMOX, IPM, MEPM, and AMK between non-ESBL-EC and ESBL-EC; however, the rate of resistance to GM, MINO, CPFX, and LVFX was higher in ESBL-EC than in non-ESBL-EC (17.5% vs. 10.0%, 19.1% vs. 7.7%, 87.5% vs. 24.2%, and 87.5% vs. 23.5%, respectively; P < 0.01). The rate of resistance to CPFX and LVFX in ESBL-EC increased throughout the study course. The rate of E. coli isolates susceptible to all the antibiotics was significantly higher in non-ESBL-EC than in ESBL-EC (68.2% vs. 7.5%; P < 0.01), and this rate decreased significantly from 10.0% in 2012 to 3.8% in 2017 in ESBL-EC (P < 0.01).

Conclusions

Our findings indicate a changing antimicrobial resistance profile of ESBL-EC, particularly to fluoroquinolones. Determination of the prevalence and antimicrobial resistance of ESBL-EC will help physicians in selecting the initial empirical treatment for patients with ESBL-EC infections.

Widespread antimicrobial resistance among bacterial infections in a Rwandan referral hospital

BACKGROUND

Resistance among bacterial infections is increasingly well-documented in high-income countries; however, relatively little is known about bacterial antimicrobial resistance in low-income countries, where the burden of infections is high.

METHODS

We prospectively screened all adult inpatients at a referral hospital in Rwanda for suspected infection for seven months. Blood, urine, wound and sputum samples were cultured and tested for antibiotic susceptibility. We examined factors associated with resistance and compared hospital outcomes for participants with and without resistant isolates.

RESULTS

We screened 19,178 patient-days, and enrolled 647 unique participants with suspected infection. We obtained 942 culture specimens, of which 357 were culture-positive specimens. Of these positive specimens, 155 (43.4%) were wound, 83 (23.2%) urine, 64 (17.9%) blood, and 55 (15.4%) sputum. Gram-negative bacteria comprised 323 (88.7%) of all isolates. Of 241 Gram-negative isolates tested for ceftriaxone, 183 (75.9%) were resistant. Of 92 Gram-negative isolates tested for the extended spectrum beta-lactamase (ESBL) positive phenotype, 66 (71.7%) were ESBL positive phenotype. Transfer from another facility, recent surgery or antibiotic exposure, and hospital-acquired infection were each associated with resistance. Mortality was 19.6% for all enrolled participants.

CONCLUSIONS

This is the first published prospective hospital-wide antibiogram of multiple specimen types from East Africa with ESBL testing. Our study suggests that low-resource settings with limited and inconsistent access to the full range of antibiotic classes may bear the highest burden of resistant infections. Hospital-acquired infections and recent antibiotic exposure are associated with a high proportion of resistant infections. Efforts to slow the development of resistance and supply effective antibiotics are urgently needed.

[Urosepsis]

Urosepsis is defined as a severe disease due to organ failure caused by a urinary tract infection. An empirical antibiotic therapy should be instigated within the first hour after diagnosis. Urine cultures and blood cultures should be performed before antibiotic treatment. Further diagnostics should be carried out at an early stage to enable an interventional focus control in the case of urinary tract obstruction or abscess formation, if necessary. Gram-negative pathogens are most frequently isolated. Extended spectrum beta-lactamase (ESBL) forming bacteria as a cause of urosepsis are increasing. Carbapenemase-forming Enterobacteriaceae, on the other hand, are still rare. The empirical treatment consists of a broad spectrum beta-lactam antibiotic. While piperacillin/tazobactam, carbapenems and the new cephalosporin/beta-lactamase inhibitor (BLI) combinations are given as monotherapy, cephalosporins should be combined with aminoglycosides (preferred) or fluoroquinolones. If a combination therapy is given, it should be de-escalated to a monotherapy after 48-72 h.

What the Clinical Microbiologist Should Know About Pharmacokinetics/Pharmacodynamics in the Era of Emerging Multidrug Resistance: Focusing on β-Lactam/β-Lactamase Inhibitor Combinations

As a class, β-lactamase inhibitors have proved successful in extending the clinical utility of β-lactam antibiotics by circumventing β-lactamase-mediated resistance. However, the rapid evolution of these β-lactamases calls for a critical reevaluation of the relationships between susceptibility, drug exposures, and bacterial response. The existing paradigm for in vitro susceptibility testing and development of β-lactam/β-lactamase inhibitor combinations may not optimally facilitate clinical use. Thus, alternative approaches for pairing these combinations and evaluating in vitro susceptibility are needed to provide better guidance to clinicians.

[Urosepsis]

Urosepsis is defined as a severe disease due to organ failure caused by a urinary tract infection. An empirical antibiotic therapy should be instigated within the first hour after diagnosis. Urine cultures and blood cultures should be performed before antibiotic treatment. Further diagnostics should be carried out at an early stage to enable an interventional focus control in the case of urinary tract obstruction or abscess formation, if necessary. Gram-negative pathogens are most frequently isolated. Extended spectrum beta-lactamase (ESBL) forming bacteria as a cause of urosepsis are increasing. Carbapenemase-forming Enterobacteriaceae, on the other hand, are still rare. The empirical treatment consists of a broad spectrum beta-lactam antibiotic. While piperacillin/tazobactam, carbapenems and the new cephalosporin/beta-lactamase inhibitor (BLI) combinations are given as monotherapy, cephalosporins should be combined with aminoglycosides (preferred) or fluoroquinolones. If a combination therapy is given, it should be de-escalated to a monotherapy after 48-72 h.

Direct use of eazyplex® SuperBug CRE assay from positive blood cultures in conjunction with inpatient infectious disease consulting for timely appropriate antimicrobial therapy in Escherichia coli and Klebsiella pneumoniae bloodstream infections

Objectives: To describe a rapid workflow based on the direct detection of Escherichia coli (Ec) and Klebsiella pneumoniae (Kp) producing CTX-M extended-spectrum β-lactamase (ESBL) and/or carbapenemases (eg, KPC, VIM) from blood cultures (BCs) and the infectious disease (ID) consulting for timely appropriate antimicrobial therapy. Methods: This observational, retrospective study included adult patients with a first episode of Ec or Kp bloodstream infection (BSI) in a large Italian university hospital, where an inpatient ID consultation team (IDCT) has been operational. Results from the BCs tested for detecting bla _CTX-M, bla _KPC, bla _NDM, bla _OXA-48-like, and bla _VIM genes by the eazyplex^® SuperBug CRE assay in Ec and Kp organisms had been notified for antimicrobial therapy consulting. Results: In 321 BSI episodes studied, we found that 151 (47.0%) of Ec or Kp organisms harbored bla _CTX-M and/or bla _KPC and/or bla _VIM (meantime from BC collection: 18.5 h). Empirical antimicrobial treatment was appropriate in 21.8% (33/151) of BSIs, namely 5.9% (3/51) of BSIs caused by KPC/VIM producers and 30.0% (30/100) of BSIs caused by CTX-M producers. After notification of results, the IDCT modified antimicrobial therapy (mean time from BC collection: 20 h) such that the proportion of appropriate treatments increased to 84.8% (128/151) of BSIs, namely 70.6% (36/51) of BSIs caused by KPC/VIM producers and 92.0% (92/100) of BSIs caused by CTX-M producers. Conclusion: Our study shows that a rapid diagnostic-driven clinical strategy allowed for early prescription of potentially effective antimicrobial therapy in BSIs caused by CTX-M ESBL- and/or KPC/VIM carbapenemase-producing Ec and Kp organisms.

Reversing resistance to counter antimicrobial resistance in the World Health Organisation's critical priority of most dangerous pathogens

The speed at which bacteria develop antimicrobial resistance far outpace drug discovery and development efforts resulting in untreatable infections. The World Health Organisation recently released a list of pathogens in urgent need for the development of new antimicrobials. The organisms that are listed as the most critical priority are all Gram-negative bacteria resistant to the carbapenem class of antibiotics. Carbapenem resistance in these organisms is typified by intrinsic resistance due to the expression of antibiotic efflux pumps and the permeability barrier presented by the outer membrane, as well as by acquired resistance due to the acquisition of enzymes able to degrade β-lactam antibiotics. In this perspective article we argue the case for reversing resistance by targeting these resistance mechanisms - to increase our arsenal of available antibiotics and drastically reduce antibiotic discovery times - as the most effective way to combat antimicrobial resistance in these high priority pathogens.

Outcomes analysis in patients with extended-spectrum beta-lactamase bacteremia empirically treated with piperacillin/tazobactam versus carbapenems

Infections caused by extended-spectrum beta-lactamase (ESBL)-producing bacteria are associated with worse outcomes and have limited treatment options. Carbapenems remain the drug of choice for these infections due to evidence of a mortality benefit and the mixed clinical efficacy associated with piperacillin/tazobactam (PTZ). Though definitive treatment for ESBL infections is well defined, evidence for appropriate empiric therapy remains inconclusive, and the role of rapid molecular assays that identify ESBL has not been evaluated. This multicenter retrospective study at nine Baylor Scott & White Health sites included patients who had positive blood cultures with ESBL-producing bacteria identified by rapid molecular assay and were empirically prescribed PTZ or carbapenems. A total of 117 patients were included in the study; 66 received empiric PTZ and 51 received carbapenems. Results showed no difference in hospital mortality (3% vs 7.8%, P = 0.4), hospital length of stay (6.1% vs 5.9%, P = 0.88), intensive care unit length of stay (4.7% vs 3.3%, P = 0.39), or recurrent ESBL bacteremia (7.6% vs 7.8%, P = 0.99) between the PTZ and carbapenem empiric treatment groups, respectively. In the era of rapid molecular assays, these results suggest that empiric PTZ use and avoidance of empiric carbapenem therapy in the first 24 hours of infection can be considered until a microbiological diagnosis is confirmed.

Infections Caused by Carbapenemase-Producing Klebsiella pneumoniae: Microbiological Characteristics and Risk Factors

The spread of carbapenemase-producing Klebsiella pneumoniae (CPKP) worldwide is a serious problem. This retrospective, matched case–control, parallel study in a tertiary teaching hospital analyzed the microbiological and clinical characteristics of CPKP infection, focusing on the risk factors for carbapenem resistance and patient mortality. The hospital department with the highest incidence of CPKP infections was the intensive care unit. All CPKP strains examined were positive for bla_kpc-2, and 84.8% of CPKP were ST11. Hypervirulent phenotype was identified in 22.7% of the patients with CPKP, with these strains displaying a high incidence of positivity for entB, ybtS, and iutA. Multivariate conditional logistic regression analysis demonstrated that Pitt bacteremia score >4, prior stomach tube, continuous renal replacement therapy (CRRT), and previous carbapenem exposure were associated with CPKP infection. Higher albumin concentration and use of cephalosporins after diagnosis were strong prognostic factors for crude 28-day mortality. Further, high APACHE II score, CRRT, use of carbapenems after diagnosis, and bacteremia were risk factors for crude in-hospital mortality. CPKP isolates showed clonal spread and were resistant to most antibiotics, resulting in higher financial burden. Critical illness was associated with increased mortality.

Carbapenem versus Cefepime or Piperacillin-Tazobactam for Empiric Treatment of Bacteremia Due to Extended-Spectrum-β-Lactamase-Producing Escherichia coli in Patients with Hematologic Malignancy

Infections with extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli are common in patients with hematologic malignancy. The utility of cefepime and piperacillin-tazobactam as empiric therapy for ESBL-producing E. coli bacteremia in patients with hematologic malignancy is largely unknown. We conducted a single-center, retrospective cohort review of 103 adult inpatients with leukemia and/or hematopoietic stem cell transplant (HCT) recipients with monomicrobial ESBL-producing E. coli bacteremia. No association between increased 14-day mortality and empiric treatment with cefepime (8%) or piperacillin-tazobactam (0%) relative to that with carbapenems (19%) was observed (P = 0.19 and P = 0.04, respectively). This observation was consistent in multivariate Cox proportional hazards models adjusted for confounding and an inverse probability of treatment-weighted (IPTW) Cox proportional hazards model. Both fever and persistent bacteremia were more common in patients treated empirically with cefepime or piperacillin-tazobactam. Empiric treatment with cefepime or piperacillin-tazobactam did not result in increased mortality relative to that with treatment with carbapenems in patients with hematologic malignancy and ESBL-producing E. coli bacteremia, although most patients were changed to carbapenems early in treatment. However, due to prolonged fever and persistent bacteremia, their role may be limited in this patient population.

Optimal Piperacillin-Tazobactam Dosing Strategies against Extended-Spectrum-β-Lactamase-Producing Enterobacteriaceae

Piperacillin-tazobactam has been proposed as an alternative to carbapenems for the treatment of infections caused by extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae However, limited understanding of optimal dosing strategies for this combination may curtail its utility. In this study, we correlated various exposures of piperacillin-tazobactam to efficacy, using a modified pharmacokinetic/pharmacodynamic index. Using a clinical Klebsiella pneumoniae isolate expressing CTX-M-15, piperacillin MIC values were determined with increasing tazobactam concentrations and fitted to a sigmoid inhibitory maximum effect (E _max) model. A hollow-fiber infection model (HFIM) was used to evaluate the efficacy of escalating tazobactam dosing with a fixed piperacillin exposure. Simulated drug concentrations from the HFIM were incorporated in the E _max model to determine the percentage of free time above instantaneous MIC (%fT>MICi) associated with each experimental exposure. The target %fT>MICi associated with growth suppression was prospectively validated using an SHV-12-producing isolate of Escherichia coli and 2 other CTX-M-15-producing K. pneumoniae isolates. Based on our reference isolate, piperacillin-tazobactam exposures of %fT>MICi of ≥55.1% were associated with growth suppression. Despite underlying differences, these findings were consistent with prospective observations in 3 other clinical isolates. Our modeling approach can be applied relatively easily in the clinical setting, and it appeared to be robust in predicting the effectiveness of various piperacillin-tazobactam exposures. This modified pharmacokinetic/pharmacodynamic index could be used to characterize response to other β-lactam/β-lactamase inhibitor combinations.

A Decision Tree Using Patient Characteristics to Predict Resistance to Commonly Used Broad-Spectrum Antibiotics in Children With Gram-Negative Bloodstream Infections

BACKGROUND

As rates of multidrug-resistant gram-negative infections rise, it is critical to recognize children at high risk of bloodstream infections with organisms resistant to commonly used empiric broad-spectrum antibiotics. The objective of the current study was to develop a user-friendly clinical decision aid to predict the risk of resistance to commonly prescribed broad-spectrum empiric antibiotics for children with gram-negative bloodstream infections.

METHODS

This was a longitudinal retrospective cohort study of children with gram-negative bacteria cared for at a tertiary care pediatric hospital from June 2009 to June 2015. The primary outcome was a bloodstream infection due to bacteria resistant to broad-spectrum antibiotics (ie, cefepime, piperacillin-tazobactam, meropenem, or imipenem-cilastatin). Recursive partitioning was used to develop the decision tree.

RESULTS

Of 689 episodes of gram-negative bloodstream infections included, 31% were resistant to broad-spectrum antibiotics. The decision tree stratified patients into high- or low-risk groups based on prior carbapenem treatment, a previous culture with a broad-spectrum antibiotic resistant gram-negative organism in the preceding 6 months, intestinal transplantation, age ≥3 years, and ≥7 prior episodes of gram-negative bloodstream infections. The sensitivity for classifying high-risk patients was 46%, and the specificity was 91%.

CONCLUSION

A decision tree offers a novel approach to individualize patients' risk of gram-negative bloodstream infections resistant to broad-spectrum antibiotics, distinguishing children who may warrant even broader antibiotic therapy (eg, combination therapy, newer β-lactam agents) from those for whom standard empiric antibiotic therapy is appropriate. The constructed tree needs to be validated more widely before incorporation into clinical practice.

A novel framework to compare the effectiveness of β-lactamase inhibitors against extended-spectrum β-lactamase-producing Enterobacteriaceae

OBJECTIVES

Extended-spectrum β-lactamases (ESBLs) present a serious challenge in the treatment of Gram-negative bacterial infections. ESBLs mediate resistance to most β-lactams, which may be reversed with the addition of an active β-lactamase inhibitor (such as tazobactam, relebactam and avibactam). However, various ESBLs may exhibit different susceptibilities to these inhibitors, which could impact efficacy. We proposed a framework for comparing the efficacy of these inhibitors when combined with the same β-lactam.

METHODS

Three clinical isolates of Klebsiella pneumoniae harbouring CTX-M-15 and one Escherichia coli isolate with SHV-12 were examined. Piperacillin MICs were determined by broth dilution using escalating concentrations of tazobactam, relebactam and avibactam. The resulting MICs were characterized as response to inhibitor concentrations using an inhibitory sigmoid E_max model. Using the best-fit parameter values, the model was conditioned with fluctuating inhibitor concentrations to simulate instantaneous MIC_i profiles for each isolate-inhibitor pair. Using a simulated exposure of 4 g piperacillin every 8 h, %fT > MIC_i was estimated for each piperacillin/inhibitor combination. A hollowfibre infection model was subsequently used to validate the predicted effectiveness of selected combinations.

RESULTS

In all scenarios, piperacillin MIC reductions were well characterized with increasing inhibitor concentrations. As predicted by %fT > MIC_i, combining piperacillin with avibactam (61.4%-73.6%) was found to be superior to tazobactam (13.5%-44.5%) for suppressing bacterial growth over time.

CONCLUSION

We illustrated a practical approach to compare the performance of different inhibitors. This platform may be used clinically to identify the optimal pairing of various β-lactams and β-lactamase inhibitors for individual isolates producing ESBLs.

Piperacillin-Tazobactam Versus Carbapenems for the Treatment of Nonbacteremic Urinary Tract Infections due to Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae

Background: Carbapenems are the drug of choice for treatment of infections due to extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae. Current evidence regarding piperacillin-tazobactam (PTZ) as an effective treatment alternative remains controversial. The purpose of this study was to determine the efficacy of PTZ versus carbapenems for treatment of nonbacteremic urinary tract infections (UTIs) due to ESBL-producing Enterobacteriaceae. Methods: A retrospective cohort study of patients treated for ESBL-related UTIs was conducted at three medical centers in the greater Middle Tennessee area. Patients were included if they were ≥ 18 years old, had a positive urine culture with an ESBL-producing organism, and received ≥ 48 hours of treatment with PTZ or carbapenem. Patients with bacteremia as well as those with isolates resistant to the treatment regimen selected were excluded. The primary objective was to determine the difference in clinical response between PTZ and carbapenem for treatment of ESBL-related UTIs. Clinical response was defined as absence of all of the following: (1) repeat admission for UTI caused by the same organism within 6 months, (2) repeat urine culture within 6 months showing growth of the same organism, or (3) a change in antimicrobial regimen due to subjective failure as determined by the ordering provider. Results: A total of 180 patients were included in the analysis (PTZ = 39; carbapenem = 141). There was no difference in clinical response between patients receiving PTZ and carbapenem (74.4% versus 80.9%; P = .38). Conclusion: PTZ may be an effective alternative to carbapenems for treatment of nonbacteremic UTIs due to ESBL-producing Enterobacteriaceae.

Epidemiology of Bloodstream Infections Caused by Escherichia coli and Klebsiella pneumoniae That Are Piperacillin-Tazobactam-Nonsusceptible but Ceftriaxone-Susceptible

Background

Piperacillin-tazobactam-nonsusceptible (TZP-NS) Enterobacteriaceae are typically also resistant to ceftriaxone. We recently encountered bacteremias due to Escherichia coli (Ec) and Klebsiella pneumoniae (Kp) that were TZP-NS but ceftriaxone-susceptible (CRO-S).

Methods

We reviewed all Ec and Kp bacteremias from 2011 to 2015 at our center and assessed the prevalence, antimicrobial susceptibilities, genetic profiles, patient characteristics, treatments, and outcomes of TZP-NS/CRO-S infections. We identified risk factors for TZP-NS/CRO-S infections compared with Ec and Kp bacteremias that were TZP-S and CRO-S (Control Group 1) and compared outcomes of patients with TZP-NS/CRO-S bacteremias, Control Group 1, and patients bacteremic with extended-spectrum β-lactamase (ESBL)–producing Ec and Kp.

Results

There were 1857 Ec and Kp bacteremia episodes, of which 78 (4.2%) were TZP-NS/CRO-S (Ec: 50/1227 [4.1%]; Kp: 28/630 [4.4%]). All TZP-NS/CRO-S isolates were also ampicillin-sulbactam-NS. Of 32 TZP-NS/CRO-S isolates that were sequenced, 28 (88%) harbored bla_TEM-1 or bla_SHV-1, none had an ESBL or AmpC β-lactamase gene, and many sequence types were represented. Independent risk factors for TZP-NS/CRO-S bacteremia were exposure to β-lactam/β-lactamase inhibitors (BL/BLIs; adjusted odds ratio [aOR], 5.5; P < .001) and cephalosporins (aOR, 3.0; P = .04). Thirty-day mortality after TZP-NS/CRO-S bacteremia was 25%, which was similar to control groups and was similar in patients treated empirically with BL/BLIs compared with those treated with cephalosporins or carbapenems. Targeted therapy with cephalosporins did not yield a higher 30-day mortality rate than carbapenem therapy.

Conclusions

TZP-NS/CRO-S Ec and Kp are emerging causes of bacteremia, and further research is needed to better understand the epidemiology, resistance mechanisms, and clinical impact of these strains.

Effect of Piperacillin-Tazobactam vs Meropenem on 30-Day Mortality for Patients With E coli or Klebsiella pneumoniae Bloodstream Infection and Ceftriaxone Resistance: A Randomized Clinical Trial

IMPORTANCE

Extended-spectrum β-lactamases mediate resistance to third-generation cephalosporins (eg, ceftriaxone) in Escherichia coli and Klebsiella pneumoniae. Significant infections caused by these strains are usually treated with carbapenems, potentially selecting for carbapenem resistance. Piperacillin-tazobactam may be an effective "carbapenem-sparing" option to treat extended-spectrum β-lactamase producers.

OBJECTIVES

To determine whether definitive therapy with piperacillin-tazobactam is noninferior to meropenem (a carbapenem) in patients with bloodstream infection caused by ceftriaxone-nonsusceptible E coli or K pneumoniae.

DESIGN, SETTING, AND PARTICIPANTS

Noninferiority, parallel group, randomized clinical trial included hospitalized patients enrolled from 26 sites in 9 countries from February 2014 to July 2017. Adult patients were eligible if they had at least 1 positive blood culture with E coli or Klebsiella spp testing nonsusceptible to ceftriaxone but susceptible to piperacillin-tazobactam. Of 1646 patients screened, 391 were included in the study.

INTERVENTIONS

Patients were randomly assigned 1:1 to intravenous piperacillin-tazobactam, 4.5 g, every 6 hours (n = 188 participants) or meropenem, 1 g, every 8 hours (n = 191 participants) for a minimum of 4 days, up to a maximum of 14 days, with the total duration determined by the treating clinician.

MAIN OUTCOMES AND MEASURES

The primary outcome was all-cause mortality at 30 days after randomization. A noninferiority margin of 5% was used.

RESULTS

Among 379 patients (mean age, 66.5 years; 47.8% women) who were randomized appropriately, received at least 1 dose of study drug, and were included in the primary analysis population, 378 (99.7%) completed the trial and were assessed for the primary outcome. A total of 23 of 187 patients (12.3%) randomized to piperacillin-tazobactam met the primary outcome of mortality at 30 days compared with 7 of 191 (3.7%) randomized to meropenem (risk difference, 8.6% [1-sided 97.5% CI, -∞ to 14.5%]; P = .90 for noninferiority). Effects were consistent in an analysis of the per-protocol population. Nonfatal serious adverse events occurred in 5 of 188 patients (2.7%) in the piperacillin-tazobactam group and 3 of 191 (1.6%) in the meropenem group.

CONCLUSIONS AND RELEVANCE

Among patients with E coli or K pneumoniae bloodstream infection and ceftriaxone resistance, definitive treatment with piperacillin-tazobactam compared with meropenem did not result in a noninferior 30-day mortality. These findings do not support use of piperacillin-tazobactam in this setting.

TRIAL REGISTRATION

anzctr.org.au Identifiers: ACTRN12613000532707 and ACTRN12615000403538 and ClinicalTrials.gov Identifier: NCT02176122.

Treatment of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBLs) infections: what have we learned until now?

The spread of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-PE) has dramatically increased worldwide, and this “evolving crisis” is currently regarded as one of the most important public health threats. The growing problem of ESBL-PE antimicrobial resistance seems to have a dual face between “Scylla and Charybdis”: on one hand the potential for rapid spread and dissemination of resistance mechanisms and on the other hand the injudicious overuse of antimicrobial agents and the inadequate infection control measures, especially in the health-care setting. Given the World Health Organization’s warning against a “post antibiotic era”, health-care providers are at a critical standpoint to find a “balance” between safe and effective ESBL-PE treatment and avoidance of inducing further resistance mechanisms. The aim of the review is to summarize the updated published knowledge in an attempt to answer basic everyday clinical questions on how to proceed to effective and the best ESBL-PE treatment options based on the existing published data.

No association between resistance mutations, empiric antibiotic, and mortality in ceftriaxone-resistant Escherichia coli and Klebsiella pneumoniae bacteremia

The objective of this study was to correlate resistance mutations of extended spectrum beta-lactamases (ESBL) and AmpC beta-lactamases and virulence factors (VF) with 30-day mortality in patients treated with either piperacillin-tazobactam or carbapenems. A post-hoc analysis on 123 patients with ceftriaxone-resistant Escherichia coli and Klebsiella pneumoniae bacteremia treated empirically with piperacillin-tazobactam and carbapenems was performed. Beta-lactamase resistance mutations and VF were identified by whole genome sequencing (WGS). The primary endpoint was 30-day mortality. Multivariate analyses were performed using logistic regression. WGS showed diverse multilocus sequence types (MLST) in 43 K. pneumoniae strains, while ST131 predominated in E. coli strains (57/80). CTX-M was most commonly detected (76/80 [95%] of E. coli; 39/43 [91%] of K pneumoniae.), followed by OXA (53/80 [66%] of E. coli; 34/43 [79%] of K. pneumoniae). A significant correlation was found between the number of genes encoding third-generation cephalosporin-resistant beta-lactamases and 30-day mortality (p = 0.045). The positive association was not significant after controlling for empiric carbapenem, Pitt score 3 and K. pneumoniae (OR 2.43, P = 0.073). None of the VF was associated with 30-day mortality. No association was found between 30-day mortality and any ESBL and AmpC beta-lactamases or VF when piperacillin-tazobactam or carbapenems were given. No significant association between 30-day mortality and active empiric therapy was found.

Relationship between digestive tract colonization and subsequent ventilator-associated pneumonia related to ESBL-producing Enterobacteriaceae

BACKGROUND

Ventilator-associated pneumonia (VAP) is the most common ICU-acquired infection. Recently, the incidence of extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBLE) has substantially increased in critically ill patients. Identifying patients at risk for VAP related to ESBLE could be helpful to improve the rate of appropriate initial antibiotic treatment, and to reduce unnecessary exposure to carbapenems. The primary objective was to identify risk factors for VAP related to ESBLE. Secondary objective was to determine the impact of ESBLE on outcome in VAP patients.

METHODS

This retrospective study was conducted in a single mixed intensive care unit (ICU), during a 4-year period. All patients with confirmed VAP were included. VAP was defined using clinical, radiologic and quantitative microbiological data. VAP first episodes were prospectively identified using the continuous surveillance data. Exposure to different risk factors was taken into account until the diagnosis of ESBLE VAP or until ICU discharge, in patients with ESBLE VAP and VAP related to other bacteria, respectively. In all patients, routine screening for ESBLE (rectal swab) was performed at ICU admission and once a week. Patients with ESBLE VAP were compared with those with VAP related to other bacteria using univariate analysis. All significant factors were included in the multivariate logistic regression model.

RESULTS

Among the 410 patients with VAP, 43 (10.5%) had ESBLE VAP, 76 (19%) patients had polymicrobial VAP and 189 (46%) had VAP related to multidrug resistant bacteria. Multivariate analysis identified prior ESBLE colonization of the digestive tract as the only independent risk factor for ESBLE VAP (OR [95% CI] = 23 [10-55], p < 0.001). Whilst the positive predictive value of ESBLE digestive colonization was low (43.6%), its negative predictive value was excellent (97.3%) in predicting ESBLE VAP. Duration of mechanical ventilation (median [IQR], 28 [18,42] vs 23 [15,42] d, p = 0.4), length of ICU stay (31 [19,53] vs 29 [18,46] d, p = 0.6), and mortality rates (55.8% vs 50%, p = 0.48) were similar in ESBLE VAP, compared with VAP related to other bacteria.

CONCLUSION

Digestive tract colonization related to ESBLE is independently associated with ESBLE VAP. Its excellent negative predictive value suggests that patients without ESBLE colonization should not receive carbapenems as part of their initial empirical treatment to cover ESBLE.

The Inoculum Effect in the Era of Multidrug Resistance: Minor Differences in Inoculum Have Dramatic Effect on MIC Determination

The observed MIC may depend on the number of bacteria initially inoculated into the assay. This phenomenon is termed the inoculum effect (IE) and is often most pronounced for β-lactams in strains expressing β-lactamase enzymes. The Clinical and Laboratory Standards Institute (CLSI)-recommended inoculum is 5 × 10⁵ CFU ml^-1 with an acceptable range of 2 × 10⁵ to 8 × 10⁵ CFU ml^-1 IE testing is typically performed using an inoculum 100-fold greater than the CLSI-recommended inoculum. Therefore, it remains unknown whether the IE influences MICs during testing performed according to CLSI guidelines. Here, we utilized inkjet printing technology to test the IE on cefepime, meropenem, and ceftazidime-avibactam. First, we determined that the inkjet dispense volume correlated well with the number of bacteria delivered to microwells in 2-fold (R² = 0.99) or 1.1-fold (R² = 0.98) serial dilutions. We then quantified the IE by dispensing orthogonal titrations of bacterial cells and antibiotics. For cefepime-resistant and susceptible dose-dependent strains, a 2-fold increase in inoculum resulted in a 1.6 log₂-fold increase in MIC. For carbapenemase-producing strains, each 2-fold reduction in inoculum resulted in a 1.26 log₂-fold reduction in meropenem MIC. At the lower end of the CLSI-allowable inoculum range, minor error rates of 34.8% were observed for meropenem when testing a resistant-strain set. Ceftazidime-avibactam was not subject to an appreciable IE. Our results suggest that IE is sufficiently pronounced for meropenem and cefepime in multidrug-resistant Gram-negative pathogens to affect categorical interpretations during standard laboratory testing.

Emerging and re-emerging infectious disease in otorhinolaryngology

SUMMARY

Emerging and re-emerging infectious disease in otorhinolaryngology (ENT) are an area of growing epidemiological and clinical interest. The aim of this section is to comprehensively report on the epidemiology of key infectious disease in otorhinolaryngology, reporting on their burden at the national and international level, expanding of the need of promoting and implementing preventive interventions, and the rationale of applying evidence-based, effective and cost- effective diagnostic, curative and preventive approaches. In particular, we focus on i) ENT viral infections (HIV, Epstein-Barr virus, Human Papilloma virus), retrieving the available evidence on their oncogenic potential; ii) typical and atypical mycobacteria infections; iii) non-specific granulomatous lymphadenopathy; iv) emerging paediatric ENT infectious diseases and the prevention of their complications; v) the growing burden of antimicrobial resistance in ENT and the strategies for its control in different clinical settings. We conclude by outlining knowledge gaps and action needed in ENT infectious diseases research and clinical practice and we make references to economic analysis in the field of ENT infectious diseases prevention and care.

Point prevalence surveys of antimicrobial use among eight neonatal intensive care units in India: 2016

BACKGROUND

Information about antimicrobial use is scarce and poorly understood among neonatal intensive care units (NICUs) in India. In this study, we describe antimicrobial use in eight NICUs using four point prevalence surveys (PPSs).

METHODS

As part of the Global Antimicrobial Resistance, Prescribing, and Efficacy in Neonates and Children (GARPEC) study, one-day, cross-sectional, hospital-based PPSs were conducted four times between 1 February 2016 and 28 February 2017 in eight NICUs. Using a standardized web-based electronic data entry form, detailed data were collected for babies on antimicrobials.

RESULTS

A total of 403 babies were admitted to NICUs across all survey days, and 208 (51.6%) were prescribed one or more antimicrobials. Among 208 babies, 155 (74.5%) were prescribed antimicrobials for treatment of an active infection. Among 155 babies with an active infection, treatment was empiric in 109 (70.3%). Sepsis (108, 49.1%) was the most common reason for prescribing antimicrobials. Amikacin (17%) followed by meropenem (12%) were the two most commonly prescribed antimicrobials. For community-acquired sepsis, piperacillin-tazobactam (17.5%) was the most commonly prescribed drug. A combination of ampicillin and gentamicin was prescribed in only two babies (5%).

CONCLUSIONS

The recommended first-line antimicrobial agents, ampicillin and gentamicin, were rarely prescribed in Indian NICUs for community acquired neonatal sepsis.

[Antibiotic Stewardship 2.0. Individualization of therapy]

Antibiotic resistance is a part of bacterial evolution and therefore unavoidable. In the context of missing novel treatment options, the restrictive use of available antibiotics in order to decelerate the spread of resistance is of high importance. This is the aim of Antibiotic Stewardship (ABS). ABS consists of two sides: a structural one and an individual one. The former deals with the formation of ABS teams, the analysis of antibiotic usage and resistance development, and the implementation of certain measures to improve antibiotic use; the latter is reflected by concrete bedside decisions: How can (broad) spectrum antibiotics be spared without harming the patient? This can be achieved, for example, by de-escalation, limiting duration of treatment, and avoiding nonindicated use. Typical nonindicated uses in both in- and outpatients are viral respiratory tract infections, asymptomatic bacteriuria and nonbacterial exacerbations of chronic obstructive pulmonary disease. Furthermore, respiratory colonization in ventilated patients, ventilator-associated tracheobronchitis, "prolonged" perioperative prophylaxis, and contaminated blood cultures reflect situations where antibiotics should be avoided. In the future, ABS will benefit from accelerated pathogen and resistance detection because early adequate treatment not only lowers the usage of antibiotics but can also improve patient outcome.

Point-Counterpoint: Piperacillin-Tazobactam Should Be Used To Treat Infections with Extended-Spectrum-Beta-Lactamase-Positive Organisms

INTRODUCTIONBeta-lactam/beta-lactamase inhibitor combination antimicrobials (BLBLIs) are among the most controversial classes of antibiotic agents available for the treatment of infections caused by extended-spectrum-beta-lactamase (ESBL)-producing Gram-negative bacteria (ESBL-GNR). Piperacillin-tazobactam (PTZ) is one of the most frequently utilized antibiotic agents for empirical Gram-negative bacterial coverage and remains active against a large proportion of ESBL-GNR strains. Furthermore, good antimicrobial stewardship practices encourage the use of carbapenem-sparing treatment regimens for infections due to ESBL-GNR. As rapid diagnostics are increasingly used in the clinical microbiology laboratory and have the capability of detecting CTX-M type or other ESBL resistance mechanisms, this issue continues to be pertinent. Some data imply reduced efficacy of PTZ against ESBLs. Several factors may affect a clinician's choice to use BLBLIs, including the isolate's MIC, the site and severity of infection, and the type of resistance mechanism. These factors are explored in this review of the pros and cons of BLBLI treatment of invasive infections due to ESBL-producing bacteria, as well as how laboratories should report results for BLBLIs for these organisms as they relate to antimicrobial stewardship. In this Point-Counterpoint, Audrey Schuetz provides the pro point of view and Sergio Reyes and Pranita Tamma provide the con, counterpoint view.

Treatment of Infections Caused by Extended-Spectrum-Beta-Lactamase-, AmpC-, and Carbapenemase-Producing Enterobacteriaceae

Therapy of invasive infections due to multidrug-resistant Enterobacteriaceae (MDR-E) is challenging, and some of the few active drugs are not available in many countries. For extended-spectrum β-lactamase and AmpC producers, carbapenems are the drugs of choice, but alternatives are needed because the rate of carbapenem resistance is rising. Potential active drugs include classic and newer β-lactam-β-lactamase inhibitor combinations, cephamycins, temocillin, aminoglycosides, tigecycline, fosfomycin, and, rarely, fluoroquinolones or trimethoprim-sulfamethoxazole. These drugs might be considered in some specific situations. AmpC producers are resistant to cephamycins, but cefepime is an option. In the case of carbapenemase-producing Enterobacteriaceae (CPE), only some "second-line" drugs, such as polymyxins, tigecycline, aminoglycosides, and fosfomycin, may be active; double carbapenems can also be considered in specific situations. Combination therapy is associated with better outcomes for high-risk patients, such as those in septic shock or with pneumonia. Ceftazidime-avibactam was recently approved and is active against KPC and OXA-48 producers; the available experience is scarce but promising, although development of resistance is a concern. New drugs active against some CPE isolates are in different stages of development, including meropenem-vaborbactam, imipenem-relebactam, plazomicin, cefiderocol, eravacycline, and aztreonam-avibactam. Overall, therapy of MDR-E infection must be individualized according to the susceptibility profile, type, and severity of infection and the features of the patient.

Renal vein thrombosis complicating severe acute pyelonephritis with renal abscesses and associated bacteraemia caused by extended-spectrum beta-lactamase producing Escherichia coli

Acute pyelonephritis might be complicated by the formation of renal and perirenal abscesses and very rarely by renal vein thrombosis, which is a life-threatening condition. The main causative agents of acute pyelonephritis are enterobacteriaceae with the incidence of extended-spectrum beta-lactamase (ESBL)-producing strains increasing worldwide. We present the case of a 71-year-old Greek man with history of diabetes mellitus and recent hospitalization, who suffered from severe pyelonephritis with renal abscesses formation and associated bacteraemia caused by ESBL-producing Escherichia coli, complicated by extensive thrombosis of the ipsilateral renal vein and its branches, protruding also in the inferior venal cava. Our patient was effectively treated with anticoagulants and targeted antibiotic therapy, respectively, consisted of low molecular weight heparin transitioned to oral acenocoumarol for 3 months and 2-week course of intravenous meropenem followed by oral fosfomycin for additional 3 weeks as quidded by clinical and computed tomographic follow-up. In conclusion, in complicated urinary infections, caused by ESBL-producing enterobacteriaceae, oral fosfomycin might represent an effective option for step-down therapy of carbapenems, allowing the shortness of the duration of patient's hospitalization and carbapenem use.

The Use of Noncarbapenem β-Lactams for the Treatment of Extended-Spectrum β-Lactamase Infections

The continued rise in infections caused by extended-spectrum β-lactamase (ESBL)-producing pathogens is recognized globally as one of the most pressing concerns facing the healthcare community. Carbapenems are widely regarded as the antibiotics of choice for the treatment of ESBL-producing infections, even when in vitro activity to other β-lactams has been demonstrated. However, indiscriminant carbapenem use is not without consequence, and carbapenem overuse has contributed to the emergence of carbapenem-resistant Enterobacteriaceae. The use of non-carbapenem β-lactams for the treatment of ESBL infections has yielded conflicting results. In this review, we discuss the available data for the use of cephamycins, cefepime, piperacillin-tazobactam, ceftolozane-tazobactam, and ceftazidime-avibactam for the treatment of ESBL infections.

Gram-Negative Bacterial Infections: Research Priorities, Accomplishments, and Future Directions of the Antibacterial Resistance Leadership Group

Antimicrobial resistance in pathogenic gram-negative bacteria is one of the most pressing challenges in the field of infectious diseases and is one of 4 key areas of unmet medical need identified by the Antibacterial Resistance Leadership Group (ARLG). The mission of the Gram-Negative Committee is to advance our knowledge of these challenging infections and implement studies to improve patient outcomes. Studies have fallen primarily into 2 broad categories: prospective cohort studies and interventional trials. Among the observational studies, CRACKLE (Consortium on Resistance Against Carbapenems in Klebsiella pneumoniae and Other Enterobacteriaceae) has contributed seminal multicenter data describing risk factors and clinical outcomes of carbapenem-resistant Enterobacteriaceae (CRE) in sentinel US hospitals. Building on this success, CRACKLE II will expand the network to hospitals across the United States and Colombia. Similar protocols have been proposed to include Acinetobacter baumannii and Pseudomonas aeruginosa (SNAP and POP studies). In addition, the CREST study (Carbapenem-Resistant Enterobacteriaceae in Solid Organ Transplant Patients) has provided pivotal data on extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae and CRE carriage among solid organ transplant recipients to inform management of this vulnerable patient population. Two clinical trials to define novel ways of using an existing antibiotic, fosfomycin, to treat ESBL-producing Enterobacteriaceae (one that has completed enrollment and the other in late protocol development) will determine the clinical efficacy of fosfomycin as step-down oral therapy to treat complicated urinary tract infections. Additional clinical studies and trials using immunotherapeutic or newly approved agents are also in the planning stage, with the main goals of generating actionable data that will inform clinical decision making and facilitate development of new treatment options for highly resistant gram-negative bacterial infections.

An antibiotic stewardship exercise in the ICU: building a treatment algorithm for the management of ventilator-associated pneumonia based on local epidemiology and the 2016 Infectious Diseases Society of America/American Thoracic Society guidelines

Introduction

Management of ventilator-associated pneumonia (VAP), the most common infection in patients on mechanical ventilation, should be tailored to local microbiological data. The aim of this study was to determine susceptibility patterns of organisms causing VAP to develop a treatment algorithm based on these findings and evidence from the literature.

Materials and methods

This is a retrospective analysis of the microbiological etiology of VAP in the intensive care unit (ICU) of a Lebanese tertiary care hospital from July 2015 to July 2016. We reviewed the latest clinical practice guidelines on VAP and tried to adapt these recommendations to our setting.

Results

In all, 43 patients with 61 VAP episodes were identified, and 75 bacterial isolates caused VAP. Extensively drug-resistant (XDR) Acinetobacter baumannii was the most common organism (37%), and it had occurred endemically throughout the year. Pseudomonas aeruginosa was the next most common organism (31%), and 13% were XDR. Enterobacteriaceae (15%) and Stenotrophomonas maltophilia (12%) shared similar incidences. Our algorithm was based on guidelines, in addition to trials, systematic reviews, and meta-analyses that studied the effectiveness of available antibiotics in treating VAP.

Conclusion

Knowing that resistance can rapidly develop within a practice environment, more research is needed to identify the best strategy for the management of VAP.

Activity of Meropenem-Vaborbactam in Mouse Models of Infection Due to KPC-Producing Carbapenem-Resistant Enterobacteriaceae

Meropenem-vaborbactam (Vabomere) is highly active against Gram-negative pathogens, especially Klebsiella pneumoniae carbapenemase (KPC)-producing, carbapenem-resistant Enterobacteriaceae The objective of these studies was to evaluate the efficacy of meropenem alone and in combination with vaborbactam in mouse thigh and lung infection models. Thighs or lungs of neutropenic mice were infected with KPC-producing carbapenem-resistant Enterobacteriaceae, with meropenem MICs ranging from ≤0.06 to 8 mg/liter in the presence of 8 mg/liter vaborbactam. Mice were treated with meropenem alone or meropenem in combination with vaborbactam every 2 h for 24 h to provide exposures comparable to 2-g doses of each component in humans. Meropenem administered in combination with vaborbactam produced bacterial killing in all strains tested, while treatment with meropenem alone either produced less than 0.5 log CFU/tissue of bacterial killing or none at all. In the thigh model, 11 strains were treated with the combination of meropenem plus vaborbactam (300 plus 50 mg/kg of body weight). This combination produced from 0.8 to 2.89 logs of bacterial killing compared to untreated controls at the start of treatment. In the lung infection model, two strains were treated with the same dosage regimen of meropenem and vaborbactam. The combination produced more than 1.83 logs of bacterial killing against both strains tested compared to untreated controls at the start of treatment. Overall, these data suggest that meropenem-vaborbactam may have utility in the treatment of infections due to KPC-producing carbapenem-resistant Enterobacteriaceae.

Is It Time to Rethink the Notion of Carbapenem-Sparing Therapy Against Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae Bloodstream Infections? A Critical Review

OBJECTIVE

To present systematic recommendations for carbapenem-sparing therapy against extended-spectrum β-lactamases (ESBLs) Enterobacteriaceae bloodstream infections (BSIs) derived from a critical review of clinical data.

DATA SOURCES

A systematic literature search using PubMed and MEDLINE databases (January 1, 2012, to June 30, 2017) was performed using key MESH terms: ESBL or extended-spectrum β-lactamases and bacteremia or bloodstream infection with piperacillin/tazobactam, ciprofloxacin, levofloxacin, cefepime, cephamycins, carbapenem, doripenem, meropenem, and ertapenem. References within articles of interest were also evaluated.

STUDY SELECTION AND DATA EXTRACTION

All English language trials were considered, and results were limited to clinical efficacy trials. Articles were screened by title and abstract for inclusion.

DATA SYNTHESIS

Studies comparing noncarbapenem versus carbapenem therapy for ESBL BSIs were critically analyzed to identify heterogeneity among studies. Data abstracted included empirical or definitive therapy, patient population, dosing, source of infection and severity, infectious etiology, and outcome.

CONCLUSIONS

Completely sparing carbapenem therapy cannot be justified among patients with ESBL BSIs. Determining the source of infection is critical to identify patients for whom carbapenem-sparing therapy is appropriate.

Clinical effect of discordance in empirical treatment of cases with urinary tract infection accompanied by bacteremia

Objective

It has been shown in previous studies that inadequate empirical treatment is associated with mortality in a variety of infections caused by Gram-negative bacteria. In this study, the clinical effect of discordance in empirical treatment was investigated in patients with urinary tract infection (UTI) accompanied by bacteremia.

Material and methods

We retrospectively reviewed the files of adult (>18 years old) patients who were diagnosed with UTI in our clinic between January 2014 and December 2015. Cases in which the same causative microorganism grew in both blood and urine cultures were included in the study. Patients using ceftriaxone and carbapenem as empirical antibiotic therapy (EAT) were compared as two different groups. In cases that the ethiologic agents were extended- spectrum beta lactamase (ESBL)-producing Klebsiella pneumoniae and Escherichia coli isolates, if the microorganism was resistant to initial antibiotic treatment the situation was defined as EAT discordance, and if it was sensitive it was defined as EAT concordance.

Results

After the exclusion criteria were applied, 65 of the 266 cases examined were taken into the study. Clinical and laboratory features of cases of ceftriaxone and carbapenem groups were similar. There was no statistically significant difference between the two groups in terms of hospital stay and survival (p>0.05). Of 28 cases of ESBL-producing E. coli and K. pneumoniae, 18 were EAT discordant and 10 were EAT concordant. Clinical and laboratory features of EAT concordant and EAT discordant groups were similar. No statistically significant difference was found between the two groups in terms of hospital stay and survival (p>0.05).

Conclusion

It was considered that ceftriaxone can still be a viable option in the EAT of UTI, which is accompanied by bacteremia without severe sepsis and septic shock findings. It was concluded that EAT discordance may not have a negative effect on the duration of hospital stay and survival rates in neither total cases nor ESBL positive ones.

Appropriate non-carbapenems are not inferior to carbapenems as initial empirical therapy for bacteremia caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae: a propensity score weighted multicenter cohort study

The efficacy of empirical non-carbapenem antibiotics for extended-spectrum beta-lactamase-producing Enterobacteriaceae bacteremia (ESBL-B) is still inconclusive. We conducted a multicenter retrospective cohort study to evaluate the efficacy of empirical non-carbapenem antibiotics for treating ESBL-B. Electronic medical records of individuals who were diagnosed with ESBL-B were reviewed between January 2010 and December 2014 at four university hospitals in Korea. Patients were classified into non-carbapenem and carbapenem groups according to the empirical antibiotic regimen. Patients treated with appropriate empirical antibiotics and who subsequently received carbapenems as definitive therapy were included in the analysis. The inverse probability of treatment weights, a statistical method that adjusts baseline statistics by giving weights based on propensity score, was used. During the study period, 232 adequately treated patients with ESBL-B were included in the analysis: 49 patients in the non-carbapenem group and 183 in the carbapenem group. The baseline characteristics and severity of infection were similar after propensity score weighting. The 30-day mortality rates for the two groups were not statistically significantly different (non-carbapenems 6.3% and carbapenems 11.4%; P = 0.42). In a multivariate analysis, empirical treatment with non-carbapenem antibiotics was not associated with 30-day all-cause mortality (HR 1.02, 95% CI 0.99-1.06, P = 0.14). In a subgroup analysis, empirical treatment with piperacillin-tazobactam was also not associated with 30-day all-cause mortality (HR 1.21, 95% CI 0.37-4.00, P = 0.75). Appropriate non-carbapenems were not inferior to carbapenems as initial empirical therapy for ESBL-B.

Piperacillin-tazobactam as alternative to carbapenems for ICU patients

Several studies suggest that alternatives to carbapenems, and particulary beta-lactam/beta-lactamase inhibitor combinations, can be used for therapy of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE)-related infections in non-ICU patients. Little is known concerning ICU patients in whom achieving the desired plasmatic pharmacokinetic/pharmacodynamic (PK/PD) target may be difficult. Also, in vitro susceptibility to beta-lactamase inhibitors might not translate into clinical efficacy. We reviewed the recent clinical studies examining the use of BL/BLI as alternatives to carbapenems for therapy of bloodstream infection, PK/PD data and discuss potential ecological benefit from avoiding the use of carbapenems. With the lack of prospective randomized studies, treating ICU patients with ESBL-PE-related infections using piperacillin-tazobactam should be done with caution. Current data suggest that BL/BLI empirical use should be avoided for therapy of ESBL-PE-related infection. Also, definitive therapy should be reserved to patients in clinical stable condition, after microbial documentation and results of susceptibility tests. Optimization of administration and higher dosage should be used in order to reach pharmacological targets.

Multidrug-resistant Enterobacteriaceae, Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus: Three major threats to hematopoietic stem cell transplant recipients

Hematopoietic stem cell transplant (HSCT) recipients are uniquely threatened by the emergence of multidrug-resistant (MDR) bacteria because these patients rely on immediate active antimicrobial therapy to combat bacterial infections. This review describes the epidemiology and treatment considerations for three challenging MDR bacterial pathogens in HSCT recipients: MDR Enterobacteriaceae, including extended-spectrum β-lactamase (ESBL)-producing and carbapenem-resistant Enterobacteriaceae (CRE), Pseudomonas aeruginosa, and vancomycin-resistant Enterococcus (VRE). These bacteria are common causes of infection in this population and bacteremias caused by these organisms are associated with high mortality rates. Carbapenems remain the treatments of choice for serious infections due to ESBL-producing Enterobacteriaceae in HSCT recipients. Administration of β-lactam agents as an extended infusion is associated with improved outcomes in patients with severe infections caused by P. aeruginosa. Older agents used for the treatment of CRE and MDR P. aeruginosa infections, such as polymyxins and aminoglycosides, have major limitations. Newer agents, such as ceftazidime-avibactam and ceftolozane-tazobactam have great potential for the treatment of Klebsiella pneumoniae carbapemenase-producing CRE and MDR P. aeruginosa, respectively, but more pre-clinical and clinical data are needed to better evaluate their efficacy. Daptomycin dosages ≥8 mg/kg/day are recommended to treat VRE infections in this population, particularly in the setting of increasing daptomycin resistance. Strategies to prevent these infections include strict adherence to recommended infection control practices and multidisciplinary antimicrobial stewardship. Last, gastrointestinal screening to guide empirical therapy and the use of polymerase chain reaction-based rapid diagnostics may decrease the time to administration of appropriate therapy for these infections, thereby leading to improved outcomes.

Shifting trends in bacteriology and antimicrobial resistance among gastrointestinal fistula patients in China: an eight-year review in a tertiary-care hospital

Background

The purpose of this study was to determine the shifting trends in bacteriology and antimicrobial resistance of infectious specimens isolated from gastrointestinal (GI) fistula patients over eight years in China.

Methods

We retrospectively reviewed the microbial records of intra-abdominal specimens at a teaching hospital from 2008 to 2015. Study period was divided into the first half (2008–2011) and the second half (2012–2015). All isolates underwent antibiotic susceptibility testing by the micro dilution method.

Results

A total of 874 intra-abdominal isolates were consecutively collected from 502 GI fistula patients (mean age, 46.5 years, 71.1% male) during the study period. Patients in the second study period (2012–2015) were older (>65 years) and more likely to have experienced cancer. Over the entire study period, most infections were caused by E. coli (24.2%) and K. pneumonia (14.1%). There was a significant decrease in the proportion E. coli isolates that were extended- spectrum beta-lactamase (ESBL)-positive (P = 0.026). The proportion of E. coli resistant to imipenem increased from 14.3% in 2008–2011 to 25.9% in 2012–2015 (P = 0.037). Imipenem resistance prevalence was higher in ESBL-negative bacteria than ESBL-positive bacteria for both E. coli and K. pneumonia (P < 0.001). In Enterococcus, significant increase in resistance to ampicillin (P = 0.01) and moxifloxacin (P = 0.02) over time were observed. In Staphylococcus and fungi, rates of antibiotic resistance did not significantly change over the study period.

Conclusions

Gram-negative bacteria predominated as causative agents of intra-abdominal infections in GI fistula patients, and there was an increase in levels of resistance to certain antibiotics, particularly carbapenems. Infection control and source control are important tools available to surgeons to prevent the emergence of antibiotic-resistant pathogens.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2744-7) contains supplementary material, which is available to authorized users.

Multidrug-Resistant Bacteria in the Community: Trends and Lessons Learned

Multidrug resistant (MDR) bacteria are one of the most important threats to public health. Typically, MDR bacteria are associated with nosocomial infections. However, some MDR bacteria have become prevalent causes of community-acquired infections. The spread of MDR bacteria into the community is a crucial development, and is associated with increased morbidity, mortality, health care costs, and antibiotic use. Factors associated with community dissemination of MDR bacteria overlap but are distinct from those associated with nosocomial spread. Prevention of further community spread of MDR bacteria is of the utmost importance, and requires a multidisciplinary approach involving all stakeholders.

In vitro efficacy of 16 antimicrobial drugs against a large collection of β-lactamase-producing isolates of extraintestinal pathogenic Escherichia coli from dogs and cats

PURPOSE

The aim of this study was to assess the in vitro efficacy of candidate antimicrobials against extended-spectrum β-lactamase (ESBL)-producing isolates of extraintestinal pathogenic Escherichia coli (ExPEC) from companion animals.

METHODOLOGY

A total of 90 ESBL-producing ExPEC isolates from dogs and cats were tested for susceptibility to 16 antimicrobials with the agar dilution method. We also identified the ESBLs and AmpC β-lactamases of these isolates with PCR and DNA sequencing.Results/Key findings. All isolates were susceptible to meropenem, tebipenem and amikacin (AMK), and various proportions were susceptible to latamoxef (LMX, 97.8 %), fosfomycin (FOM, 97.8 %), faropenem (FPM, 96.7 %), nitrofurantoin (NFT, 96.7 %), flomoxef (FMX, 93.3 %), piperacillin/tazobactam (PTZ, 92.2 %), cefmetazole (CMZ, 91.1 %), chloramphenicol (80.0 %), trimethoprim/sulfamethoxazole (64.4 %), amoxicillin/clavulanic acid (63.3 %), ceftibuten (60.0 %), tetracycline (52.2 %) and enrofloxacin (10.0 %). A genetic analysis showed that 83 of the 90 (92.2 %) isolates were positive for CTX-M-type genes: CTX-M-14 (n=26), CTX-M-27 (n=20), CTX-M-55 (n=17), CTX-M-15 (n=12), CTX-M-2 (n=5), CTX-M-24 (n=2), CTX-M-104 (n=2) and CTX-M-3 (n=1). Eight isolates also expressed AmpC β-lactamase phenotypes.

CONCLUSION

This study demonstrates that the susceptibility rates to PTZ, CMZ, LMX, AMK, FOM, FPM, NFT and FMX were similar to those to carbapenems (>90 %), implying that these drugs are available alternatives to carbapenems for the treatment of companion animals infected with ExPEC-producing CTX-M-type ESBLs. Further in vivo studies of the effective use of these antimicrobials are required.

Bacteraemic urinary tract infections in a tertiary hospital in Japan: the epidemiology of community-acquired infections and the role of non-carbapenem therapy

Objectives

This study aimed to describe the epidemiology of bacteraemic urinary tract infections (UTIs), especially those that were community-acquired (i.e., with no discernible healthcare-associated exposure) and caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBLPE). We also evaluated and compared empirical antimicrobial treatments [carbapenem (CBP) vs. non-carbapenem beta-lactam (non-CBPBL)] for bacteraemic UTIs. Finally, we reviewed the published literature on the effectiveness of non-CBP compared to CBP treatments for UTIs caused by extended-spectrum beta-lactamase-producing organisms.

Results

A total of 339 bacteraemic UTI episodes were identified; 32 (9.4%) were caused by ESBLPE. In bacteraemic UTI episodes, ESBLPE accounted for 8.3% of hospital-acquired cases, 10.0% of community-acquired cases, and 8.2% of non-healthcare-associated cases. As effective empirical therapy for ESBLPE, 12 patients received CBP and 7 patients received non-CBPBL treatments [piperacillin/tazobactam (PT) or cefmetazole (CMZ)]. Age, sex, Pitt bacteraemia score, immunosuppressive status, and causative bacterial species were similar between groups; neither group experienced mortality within 14 days. The number of days to defervescence was similar between groups. No difference was noted in the rates of microbiological cure (58% vs. 57%, P = 1.0). Five of seven patients in the non-CBPBL group did not receive CBP during the treatment period, even as definitive therapy, but all experienced clinical cure.

Use of β-Lactam/β-Lactamase Inhibitors for Extended-Spectrum-β-Lactamase Infections: Defining the Right Patient Population

In a multicenter, multinational observational study that included neutropenic patients with bloodstream infections by extended-spectrum-β-lactamase-producing species, Gudiol et al. (Antimicrob. Agents Chemother. 61:e00164-17, 2017, https://doi.org/10.1128/AAC.00164-17) demonstrated that β-lactam/β-lactamase inhibitors are effective treatment options. A review of this work, however, reminds us that some lingering questions remain for specific high-risk subgroups.

Efficacy of β-Lactam/β-Lactamase Inhibitor Combinations for the Treatment of Bloodstream Infection Due to Extended-Spectrum-β-Lactamase-Producing Enterobacteriaceae in Hematological Patients with Neutropenia

β-Lactam/β-lactamase inhibitors (BLBLIs) were compared to carbapenems in two cohorts of hematological neutropenic patients with extended-spectrum-β-lactamase (ESBL) bloodstream infection (BSI): the empirical therapy cohort (174 patients) and the definitive therapy cohort (251 patients). The 30-day case fatality rates and other secondary outcomes were similar in the two therapy groups of the two cohorts and also in the propensity-matched cohorts. BLBLIs might be carbapenem-sparing alternatives for the treatment of BSI due to ESBLs in these patients.

Impact of appropriateness of empiric therapy on outcomes in community-onset bacteremia by extended-spectrum-β-lactamase producing Escherichia coli and Klebisella pneumoniae definitively treated with carbapenems

Despite a significant increase of bloodstream infection caused by extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae in the community-setting, information regarding clinical outcomes of inappropriate empiric therapy (IAT) in patients with those infections is limited. A multicenter-retrospective cohort study was conducted in four hospitals. A total of 249 adults were identified to have community-onset bacteremia caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae, and definitively treated with carbapenems. According to the appropriateness of empiric therapy, individuals were divided into an appropriate empiric therapy (AT) group (n = 106) and IAT group (n = 143). Patients who received AT showed more severe underlying conditions including underlying solid cancer, healthcare-association and intensive care unit (ICU) care, compared to the IAT group. Primary bacteremia was more commonly found in the AT group than in the IAT group, while urinary tract infection predominated more frequently in the IAT group than in the AT group. Multivariate analysis using propensity score analysis indicated that inappropriateness of empiric therapy was not an independent risk factor for 30-day death. ICU care, respiratory tract infection and underlying liver, renal and connective tissue diseases were significantly associated with mortality. In patients with bloodstream infections caused by ESBL-producing E. coli and K. pneumoniae in the community-setting, delay in appropriate therapy was not associated with an increased rate of death if the patients were definitively treated with carbapenems.