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

In Vitro Activity of Cefotetan against ESBL-Producing Escherichia coli and Klebsiella pneumoniae Bloodstream Isolates from the MERINO Trial

Extended-spectrum-beta-lactamase (ESBL)-producing Enterobacterales continue to pose a major threat to human health worldwide. Given the limited therapeutic options available to treat infections caused by these pathogens, identifying additional effective antimicrobials or revisiting existing drugs is important. Ceftriaxone-resistant Escherichia coli and Klebsiella pneumoniae containing CTX-M-type ESBLs or AmpC, in addition to narrow-spectrum OXA and SHV enzymes, were selected from blood culture isolates obtained from the MERINO trial. Isolates had previously undergone whole-genome sequencing (WGS) to identify antimicrobial resistance genes. Cefotetan MICs were determined by broth microdilution (BMD) testing with a concentration range of 0.125 to 64 mg/liter; CLSI breakpoints were used for susceptibility interpretation. BMD was performed using an automated digital antibiotic dispensing platform (Tecan D300e). One hundred ten E. coli and 40 K. pneumoniae isolates were used. CTX-M-15 and CTX-M-27 were the most common beta-lactamases present; only 7 isolates had coexistent ampC genes. Overall, 98.7% of isolates were susceptible, with MIC₅₀s and MIC₉₀s of 0.25 mg/liter and 2 mg/liter (range, ≤0.125 to 64 mg/liter), respectively. MICs appeared higher among isolates with ampC genes present, with an MIC₅₀ of 16 mg/liter, than among those containing CTX-M-15, which had an MIC₅₀ of only 0.5 mg/liter. Isolates with an ampC gene exhibited an overall susceptibility of 85%. Presence of a narrow-spectrum OXA beta-lactamase did not appear to alter the cefotetan MIC distribution. Cefotetan demonstrated favorable in vitro efficacy against ESBL-producing E. coli and K. pneumoniae bloodstream isolates.

IMPORTANCE Carbapenem antibiotics remain the treatment of choice for severe infection due to ESBL- and AmpC-producing Enterobacterales. The use of carbapenems is a major driver of the emergence of carbapenem-resistant Gram-negative bacilli, which are often resistant to most available antimicrobials. Cefotetan is a cephamycin antibiotic developed in the 1980s that demonstrates enhanced resistance to beta-lactamases and has a broad spectrum of activity against Gram-negative bacteria. Cefotetan holds potential to be a carbapenem-sparing treatment option. Data on the in vitro activity of cefotetan against ESBL-producing Enterobacterales remain scarce. Our study assessed the in vitro activity of cefotetan against ceftriaxone-nonsusceptible blood culture isolates obtained from patients enrolled in the MERINO trial.

In vivo activity of WCK 4282 (high-dose cefepime/tazobactam) against serine β-lactamase-producing Enterobacterales and Pseudomonas aeruginosa in the neutropenic murine thigh infection model

OBJECTIVES

WCK 4282, high-dose cefepime/tazobactam, possesses potent in vitro activity against Gram-negative organisms including ESBL- and cephalosporinase-harbouring strains. The purpose of this evaluation was to investigate the in vivo activity of human-simulated exposures of WCK 4282 against serine-β-lactamase-harbouring Enterobacterales and Pseudomonas aeruginosa.

METHODS

Nineteen clinical isolates were evaluated (ESBL/cephalosporinase producers, n = 8 Escherichia coli, n = 4 P. aeruginosa; KPC producers, n = 3 Klebsiella pneumoniae, n = 1 Klebsiella aerogenes; OXA-48/181 producers, n = 2 K. pneumoniae, n = 1 E. coli). WCK 4282 MICs ranged from 4 to 32 mg/L compared with 16 to >128 mg/L for cefepime. Thigh-infected neutropenic mice received cefepime, WCK 4282 or sham control over 24 h prior to harvest. Cefepime and tazobactam dosing regimens produced plasma profiles of fAUC, fT>MIC and fCmax similar to human exposure after WCK 4282 2/2 g every 8 h (1.5 h infusion).

RESULTS

Bacterial burdens (log10 cfu/thigh) were 5.81 ± 0.36 at 0 h and 9.29 ± 0.88 at 24 h in untreated controls. WCK 4282 produced potent activity against ESBL/cephalosporinase-producing strains with WCK 4282 MIC ≤16 mg/L; mean changes in log10 cfu/thigh from 0 h were -1.70 ± 0.77 and +1.86 ± 2.03 log10 cfu/thigh for WCK 4282 and cefepime human-simulated regimens, respectively. WCK 4282 produced variable activity against serine-carbapenemase-harbouring isolates. For the KPC-harbouring strains, WCK 4282 produced bacteriostasis with a mean -0.1 ± 0.61 log10 cfu/thigh. Against OXA-48/181-harbouring isolates, WCK 4282 produced a range of change in bacterial burden of -1.23 ± 0.33 to +1.04 ± 0.7 log10 cfu/thigh.

CONCLUSIONS

Human-simulated exposures of WCK 4282 produced in vivo efficacy against ESBL/cephalosporinase-producing, piperacillin/tazobactam- and ceftolozane/tazobactam-non-susceptible Enterobacterales and P. aeruginosa. These findings support further development of this combination as a carbapenem-sparing agent.

Molecular detection of plasmid-derived AmpC β-lactamase among clinical strains of Enterobacteriaceae in Bahrain

BACKGROUND

Enterobacteriaceae with AmpC β-lactamase are multidrug-resistant organisms and represent a significant challenge to patient care. This study aims to determine the prevalence of plasmid-derived AmpC β-lactamase among extended spectrum β-lactamases (ESBL)-producing Enterobacteriaceae strains in Bahrain.

METHODS

It was a cross-sectional study. A total of 185 ESBL-producing Enterobacteriaceae isolates were recovered from clinically significant specimens from January 2018 to December 2019. The samples underwent initial screen for cefoxitin resistance by disc diffusion test and subsequent phenotypic confirmation of AmpC production with phenyl boronic acid assays as well as genotypic analysis by multiplex polymerase chain reactions for AmpC subtypes. Drug-resistant features of these clinical isolates were also examined.

RESULTS

Twenty-nine ESBL-producing Enterobacteriaceae isolates were cefoxitin resistant. Phenotypic and genotypic analyses confirmed that 8 and 12 cefoxitin-resistant isolates are AmpC positive, respectively. These AmpC producers are multidrug resistant, and Escherichia coli is the dominant strain among them.

CONCLUSIONS

Plasmid-mediated spread of AmpC is present in clinically relevant Enterobacteriaceae species in Bahrain. Rational antimicrobial therapy against these multidrug-resistant organisms and continued surveillance of antimicrobial resistance mechanisms among the clinical isolates are recommended for optimal patient care.

An Evidence-Based Multidisciplinary Approach Focused at Creating Algorithms for Targeted Therapy of BSIs, cUTIs, and cIAIs Caused by Enterobacterales in Critically Ill Adult Patients

Prompt implementation of appropriate targeted antibiotic therapy represents a valuable approach in improving clinical and ecological outcome in critically septic patients. This multidisciplinary opinion article focused at developing evidence-based algorithms for targeted antibiotic therapy of bloodstream (BSIs), complicated urinary tract (cUTIs), and complicated intrabdominal infections (cIAIs) caused by Enterobacterales. The aim was to provide a guidance for intensive care physicians either in appropriately placing novel antibiotics or in considering strategies for sparing the broadest-spectrum antibiotics. A multidisciplinary team of experts (one intensive care physician, one infectious disease consultant, one clinical microbiologist and one MD clinical pharmacologist), performed several rounds of assessment to reach agreement in developing six different algorithms according to the susceptibility pattern (one each for multi-susceptible, extended-spectrum beta-lactamase-producing, AmpC beta-lactamase-producing, Klebsiella pneumoniae carbapenemase (KPC)-producing, OXA-48-producing, and Metallo-beta-lactamase (MBL)-producing Enterobacterales). Whenever multiple therapeutic options were feasible, a hierarchical scale was established. Recommendations on antibiotic dosing optimization were also provided. In order to retrieve evidence-based support for the therapeutic choices proposed in the algorithms, a comprehensive literature search was performed by a researcher on PubMed-MEDLINE from inception until March 2021. Quality and strength of evidence was established according to a hierarchical scale of the study design. Only articles published in English were included. It is expected that these algorithms, by allowing prompt revision of antibiotic regimens whenever feasible, appropriate place in therapy of novel beta-lactams, implementation of strategies for sparing the broadest-spectrum antibiotics, and pharmacokinetic/pharmacodynamic optimization of antibiotic dosing regimens, may be helpful either in improving clinical outcome or in containing the spread of antimicrobial resistance.

Lung penetration, bronchopulmonary pharmacokinetic/pharmacodynamic profile and safety of 3 g of ceftolozane/tazobactam administered to ventilated, critically ill patients with pneumonia

Objectives

Ceftolozane/tazobactam is approved for hospital-acquired/ventilator-associated bacterial pneumonia at double the dose (i.e. 2 g/1 g) recommended for other indications. We evaluated the bronchopulmonary pharmacokinetic/pharmacodynamic profile of this 3 g ceftolozane/tazobactam regimen in ventilated pneumonia patients.

Methods

This was an open-label, multicentre, Phase 1 trial (clinicaltrials.gov: NCT02387372). Mechanically ventilated patients with proven/suspected pneumonia received four to six doses of 3 g of ceftolozane/tazobactam (adjusted for renal function) q8h. Serial plasma samples were collected after the first and last doses. One bronchoalveolar lavage sample per patient was collected at 1, 2, 4, 6 or 8 h after the last dose and epithelial lining fluid (ELF) drug concentrations were determined. Pharmacokinetic parameters were estimated by non-compartmental analysis and pharmacodynamic analyses were conducted to graphically evaluate achievement of target exposures (plasma and ELF ceftolozane concentrations >4 mg/L and tazobactam concentrations >1 mg/L; target in plasma: ≥30% and ≥20% of the dosing interval, respectively).

Results

Twenty-six patients received four to six doses of study drug; 22 were included in the ELF analyses. Ceftolozane and tazobactam T_max (6 and 2 h, respectively) were delayed in ELF compared with plasma (1 h). Lung penetration, expressed as the ratio of mean drug exposure (AUC) in ELF to plasma, was 50% (ceftolozane) and 62% (tazobactam). Mean ceftolozane and tazobactam ELF concentrations remained >4 mg/L and >1 mg/L, respectively, for 100% of the dosing interval. There were no deaths or adverse event-related study discontinuations.

Conclusions

In ventilated pneumonia patients, 3 g of ceftolozane/tazobactam q8h yielded ELF exposures considered adequate to cover ceftolozane/tazobactam-susceptible respiratory pathogens.

Cefepime use: A need for antimicrobial stewardship

OBJECTIVES

Unlike other 3GCs, Cefepime is a cephalosporin that has, in animal model studies, shown a low risk of selecting resistant mutants. It also enables carbapenems to be saved in treatment of Pseudomonasaeruginosa and the CESP group (Citrobacter, Enterobacter, Serratia and Providencia, as well as the genus Klebsiellaaerogenes, Morganella and Hafnia), consequently producing cephalosporinase. We aimed to determine whether its prescription in a French teaching hospital met criteria for proper use.

PATIENTS AND METHODS

We conducted a retrospective study of proper cefepime use between March 1st, 2018 and February 28th, 2019, to assess indication, antimicrobial stewardship, dosing schedule, microbiological documentation, reevaluation, and treatment duration. Prescriptions were then compared to local guidelines established from international literature.

RESULTS

Out of 142 cefepime prescriptions, 97.2% were prescribed as validated according to indication. The duration of the documented treatments matched the guidelines for 56.5% of patients, dosage was adapted to the indication for 77.4% and to kidney function for 97.2%. Bacteriological documentation was performed in all cases and an antibiogram was generated in 99.2% of cases. The treatment was reassessed between 48 and 72h and between the 7th and 10th day for 44.2% and 60.9% of the prescriptions respectively. The antimicrobial stewardship team managed half of the prescriptions. Only 13.4% of prescriptions met all criteria for proper use.

CONCLUSION

Notwithstanding a highly sizable majority of validated indications, a very small proportion of cefepime prescriptions met all the criteria for proper use. In the context of increased cefepime consumption, which is favored by its increased place in the latest recommendations published in 2019, proper use of cefepime prescriptions needs to be more effectively promoted.

Infectious Diseases Society of America Guidance on the Treatment of Extended-Spectrum β-lactamase Producing Enterobacterales (ESBL-E), Carbapenem-Resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with Difficult-to-Treat Resistance (DTR-P. aeruginosa)

BACKGROUND

Antimicrobial-resistant infections are commonly encountered in US hospitals and result in significant morbidity and mortality. This guidance document provides recommendations for the treatment of infections caused by extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E), carbapenem-resistant Enterobacterales (CRE), and Pseudomonas aeruginosa with difficult-to-treat resistance (DTR-P. aeruginosa).

METHODS

A panel of 6 infectious diseases specialists with expertise in managing antimicrobial-resistant infections formulated common questions regarding the treatment of ESBL-E, CRE, and DTR-P. aeruginosa infections. Based on review of the published literature and clinical experience, the panel provide recommendations and associated rationale for each recommendation. Because of significant differences in the molecular epidemiology of resistance and the availability of specific anti-infective agents globally, this document focuses on treatment of antimicrobial-resistant infections in the United States.

RESULTS

Approaches to empiric treatment selection, duration of therapy, and other management considerations are briefly discussed. The majority of guidance focuses on preferred and alternative treatment recommendations for antimicrobial-resistant infections, assuming that the causative organism has been identified and antibiotic susceptibility testing results are known. Treatment recommendations apply to both adults and children.

CONCLUSIONS

The field of antimicrobial resistance is dynamic and rapidly evolving, and the treatment of antimicrobial-resistant infections will continue to challenge clinicians. This guidance document is current as of 17 September 2020. Updates to this guidance document will occur periodically as new data emerge. Furthermore, the panel will expand recommendations to include other problematic gram-negative pathogens in future versions. The most current version of the guidance including the date of publication can be found at www.idsociety.org/practice-guideline/amr-guidance/.

Third-generation cephalosporin resistance in clinical isolates of Enterobacterales collected between 2016-2018 from USA and Europe: genotypic analysis of β-lactamases and comparative in vitro activity of cefepime/enmetazobactam

OBJECTIVES

This study aimed to investigate third-generation cephalosporin (3GC) resistance determinants [extended-spectrum β-lactamases (ESBLs), AmpC β-lactamases and OXA-type β-lactamases] in contemporary clinical Enterobacterales isolates and to determine the in vitro activity of β-lactams and β-lactam/β-lactamase inhibitor combinations, including the investigational combination of cefepime and the novel β-lactamase inhibitor enmetazobactam.

METHODS

Antibacterial susceptibility of 7168 clinical Enterobacterales isolates obtained between 2016-2018 from North America and Europe was determined according to CLSI guidelines. Phenotypic resistance to the 3GC ceftazidime (MIC ≥ 16 µg/mL) and/or ceftriaxone (MIC ≥ 4 µg/mL) but retaining susceptibility to meropenem (MIC ≤ 1 µg/mL) was determined. β-Lactamase genotyping was performed on clinical isolates with ceftazidime, ceftriaxone, cefepime or meropenem MIC ≥ 1 µg/mL.

RESULTS

Phenotypic resistance to 3GCs occurred in 17.5% of tested isolates, whereas 2.1% of isolates were resistant to the carbapenem meropenem. Within the 3GC-resistant subgroup, 60.1% (n = 752) of isolates encoded an ESBL, 25.6% (n = 321) encoded an AmpC-type β-lactamase and 0.9% (n = 11) encoded an OXA-type β-lactamase. Susceptibility of the subgroup to piperacillin/tazobactam (57.5%) and ceftolozane/tazobactam (71.3%) was <90% based on breakpoints established by the CLSI. Projected susceptibility to cefepime/enmetazobactam was 99.6% when applying the cefepime susceptible, dose-dependent breakpoint of 8 µg/mL. Against ESBL-producing isolates (n = 801) confirmed by genotyping, only susceptibility to meropenem (96.0%) and cefepime/enmetazobactam (99.9%) exceeded 90%.

CONCLUSION

This study describes the antibacterial activity of important therapies against contemporary 3GC-resistant clinical Enterobacterales isolates and supports the development of cefepime/enmetazobactam as a carbapenem-sparing option for ESBL-producing pathogens.

In Vivo Activity of WCK 4282 (High-Dose Cefepime/Tazobactam) against Serine-β-Lactamase-Producing Enterobacterales and Pseudomonas aeruginosa in the Neutropenic Murine Lung Infection Model

WCK 4282 (cefepime 2 g-tazobactam 2 g) maximizes systemic exposure of tazobactam and restores cefepime activity against various extended-spectrum β-lactamase (ESBL)- and cephalosporinase-producing strains in vitro We describe clinical WCK 4282 exposure efficacies against various serine β-lactamase-producing Enterobacterales and Pseudomonas aeruginosa isolates in a murine pneumonia model. Clinical cefepime-resistant isolates (17 Enterobacterales and 2 P. aeruginosa) were utilized. Isolates expressed ESBLs, cephalosporinases, and/or serine carbapenemases (KPC and OXA-48-like). WCK 4282 MICs were 4 to 32 μg/ml. For in vivo experiments, lungs of neutropenic mice were inoculated using standard inoculum (10⁷ log₁₀ CFU/ml). Serine carbapenemase-producing isolates were also assessed using a low inoculum (1:5 dilution). Treatment mice received a human-simulated regimen (HSR) of cefepime, meropenem (control for serine carbapenemase expression with low inoculum experiments), or WCK 4282 human-simulated regimens. Efficacy was assessed as change in log₁₀ CFU/lungs at 24 h compared with 0-h controls. At standard inoculum, the mean 0-h bacterial burden was 6.65 ± 0.23 log₁₀ CFU/lungs, and it increased at 24 h by 2.48 ± 0.60 log₁₀ CFU/lungs among untreated controls. Initial bacterial burdens of lower inocula ranged from 5.81 ± 0.12 to 6.39 ± 0.13 log₁₀ CFU/lungs. At standard and/or low inocula, cefepime and meropenem provided minimal activity. WCK 4282 produced a >1 log₁₀ reduction against 9/9 ESBL-/cephalosporinase-producing strains. WCK 4282 provided variable activity among mice infected with standard or lower inocula of OXA-48-like-producers. WCK 4282 exposures provided 0.53 ± 1.07 log₁₀ CFU/lungs growth against KPC producers at a standard inoculum versus bacteriostasis (-0.15 ± 0.54 change in log₁₀ CFU/lungs) at a low inoculum. WCK 4282 produced potent in vivo activity against ESBL- and cephalosporinase-producing Enterobacterales and P. aeruginosa isolates and potential activity against OXA-48-like-producing Enterobacterales isolates in a neutropenic pneumonia model.

Activity of ceftolozane/tazobactam against Gram-negative isolates from patients with lower respiratory tract infections - SMART United States 2018-2019

BACKGROUND

Ceftolozane/tazobactam (C/T) is approved in 70 countries, including the United States, for the treatment of patients with hospital-acquired and ventilator-associated bacterial pneumonia caused by susceptible Gram-negative pathogens. C/T is of particular importance as an agent for the treatment of multidrug-resistant (MDR) Pseudomonas aeruginosa infections. The current study summarizes 2018-2019 data from the United States on lower respiratory tract isolates of Gram-negative bacilli from the SMART global surveillance program. The CLSI reference broth microdilution method was used to determine in vitro susceptibility of C/T and comparators against isolates of P. aeruginosa and Enterobacterales.

RESULTS

C/T inhibited 96.0% of P. aeruginosa (n = 1237) at its susceptible MIC breakpoint (≤4 μg/ml), including > 85% of meropenem-nonsusceptible and piperacillin/tazobactam (P/T)-nonsusceptible isolates and 76.2% of MDR isolates. Comparator agents demonstrated lower activity than C/T against P. aeruginosa: meropenem (74.8% susceptible), cefepime (79.2%), ceftazidime (78.5%), P/T (74.4%), and levofloxacin (63.1%). C/T was equally active against ICU (96.0% susceptible) and non-ICU (96.7%) isolates of P. aeruginosa. C/T inhibited 91.8% of Enterobacterales (n = 1938) at its susceptible MIC breakpoint (≤2 μg/ml); 89.5% of isolates were susceptible to cefepime and 88.0% susceptible to P/T. 67.1 and 86.5% of extended-spectrum β-lactamase (ESBL) screen-positive isolates of Klebsiella pneumoniae (n = 85) and Escherichia coli (n = 74) and 49.6% of MDR Enterobacterales were susceptible to C/T. C/T was equally active against ICU (91.3% susceptible) and non-ICU (92.6%) Enterobacterales isolates.

CONCLUSION

Data from the current study support the use of C/T as an important treatment option for lower respiratory tract infections including those caused by MDR P. aeruginosa.

Navigating treatment approaches for presumed ESBL-producing infections

ESBL-producing Enterobacterales (ESBL-E) remain a significant global threat. In several regions of the world, ESBLs are produced by over half of Escherichia coli or Klebsiella pneumoniae infections, contributing to significant morbidity and mortality. Though it is accepted that carbapenems are effective for the treatment of invasive ESBL-E infections, controversy remains as to whether carbapenem alternatives can be considered in select cases. Indiscriminate carbapenem use for the treatment of ESBL-E infections will likely further the international antimicrobial resistance crisis, underscoring the importance of investigating the role of non-carbapenem options. In this issue of JAC-Antimicrobial Resistance, we present a PRO/CON debate exploring whether carbapenems are necessary for all infections caused by ceftriaxone-resistant Enterobacterales.

CON: Carbapenems are NOT necessary for all infections caused by ceftriaxone-resistant Enterobacterales

Carbapenems are considered the drugs of choice for the treatment of serious infections caused by ceftriaxone-resistant Enterobacterales. However, because of the dramatic increase in carbapenem-resistant organisms worldwide, finding alternatives to carbapenems is a must. The potential options include β-lactam/β-lactamase inhibitor combinations, temocillin, cephamycins and some non-β-lactam drugs. The most controversial is piperacillin/tazobactam; the results of the MERINO trial are challenged because the isolates of patients with worse outcomes were frequently not susceptible to piperacillin/tazobactam when studied by reference methods, and also because the drug was not administered in extended infusion. Other potential options are briefly discussed. We conclude that carbapenems are not necessary for all patients with infections caused by ceftriaxone-resistant Enterobacterales.

Recent molecules in the treatment of severe infections caused by ESBL-producing bacteria

Introduction: The widespread increase in resistance to β-lactam antibiotics in Enterobacterales currently represents one of the main threats to human health worldwide. The primary mechanisms of resistance are the production of β-lactamase enzymes that are able to hydrolyze β-lactams.Areas covered: we summarize the most recent advances regarding the main characteristics and spectrum of activity of new available antibiotics and strategies for the treatment of ESBL-producing Enterobacterales infections.Expert opinion: ESBL-producing strains are recognized as a worldwide challenge in the treatment of both hospital- and community-acquired infections. Data from the literature point out the high mortality associated with severe infections due to ESBL strains, especially in patients who developed severe sepsis or septic shock, together with the importance of the source of infection and indicators of severity, as determinants of the patient's outcome. Carbapenems are currently considered the first-line therapy, although the diffusion of resistant strains is an evolving problem and is mandatory the introduction in clinical practice of new drug regimens and treatment strategies, based on clinical data, local epidemiology, and microbiology. As a possible carbapenem-sparing strategy, ceftolozane-tazobactam and ceftazidime-avibactam appear the best-available carbapenem-sparing therapies. The definitive role of new drugs should be definitively assessed.

OXA-48 Carbapenemase-Producing Enterobacterales in Spanish Hospitals: An Updated Comprehensive Review on a Rising Antimicrobial Resistance

Carbapenemase-producing Enterobacterales (CPE) are significant contributors to the global public health threat of antimicrobial resistance. OXA-48-like enzymes and their variants are unique carbapenemases with low or null hydrolytic activity toward carbapenems but no intrinsic activity against expanded-spectrum cephalosporins. CPEs have been classified by the WHO as high-priority pathogens given their association with morbidity and mortality and the scarce number of effective antibiotic treatments. In Spain, the frequency of OXA-48 CPE outbreaks is higher than in other European countries, representing the major resistance mechanism of CPEs. Horizontal transfer of plasmids and poor effective antibiotic treatment are additional threats to the correct prevention and control of these hospital outbreaks. One of the most important risk factors is antibiotic pressure, specifically carbapenem overuse. We explored the use of these antibiotics in Spain and analyzed the frequency, characteristics and prevention of CPE outbreaks. Future antibiotic stewardship programs along with specific preventive measures in hospitalized patients must be reinforced and updated in Spain.

Efficacy of loading dose colistin versus carbapenems for treatment of extended spectrum beta lactamase producing Enterobacteriaceae

Colistin provides in vitro activity against numerous ESBL-producing and carbapenem-resistant bacteria. However, clinical information with respect to its utilization in infection caused by ESBL producers is limited. The aim of this study was a comparison of mortality rates of loading dose (LD) colistin and carbapenems as definitive therapies in a cohort of patients with infections caused by ESBL-producing Escherichia coli and Klebsiella pneumoniae. A retrospective cohort study in 396 patients with ESBL-producing E.coli and K.pneumoniae infection at a university-affiliated hospital was conducted between 1 January 2005 and 30 June 2015 to compare outcomes of infected patients who received LD colistin (95 patients) with carbapenems (301 patients). The three primary outcomes were 30-day mortality, clinical response and microbiological response. The most common infection types were urinary tract infection (49.49%), followed by pneumonia (40.66%), bacteremia (13.64%), skin and soft tissue infections (4.80%) and intra-abdominal infection (3.03%). LD colistin group provided higher 30-day mortality when compared with carbapenems group (HR 7.97; 95% CI 3.68 to 17.25; P = 0.001). LD colistin was also independently associated with clinical failure (HR 4.30; 95% CI 1.93 to 9.57; P = 0.001) and bacteriological failure (HR 9.49; 95% CI 3.76 to 23.96; P = 0.001) when compared with those who received carbapenems. LD colistin treatment was associated with poorer outcomes, i.e. mortality rate, clinical response and microbiological response. Moreover, when adjusted confounding factors, LD colistin was still less effective than carbapenems. It should be noted that, however, the use of Vitek-2 to assess colistin susceptibility could provide inaccurate results. Also, the difference in baseline characteristics could still remain in retrospective study although compensation by hazard ratio adjustment was performed. Therefore, clinical utilization of LD colistin should be recommended as an alternative for treatment ESBL-producing Enterobacteriaceae only in the circumstances where carbapenems cannot be utilized, but this recommendation must be considered carefully.

Efficacy of β-lactam/β-lactamase inhibitors to treat extended-spectrum beta-lactamase-producing Enterobacterales bacteremia secondary to urinary tract infection in kidney transplant recipients (INCREMENT-SOT Project)

BACKGROUND

Whether active therapy with β-lactam/β-lactamase inhibitors (BLBLI) is as affective as carbapenems for extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) bloodstream infection (BSI) secondary to urinary tract infection (UTI) in kidney transplant recipients (KTRs) remains unclear.

METHODS

We retrospectively evaluated 306 KTR admitted to 30 centers from January 2014 to October 2016. Therapeutic failure (lack of cure or clinical improvement and/or death from any cause) at days 7 and 30 from ESBL-E BSI onset was the primary and secondary study outcomes, respectively.

RESULTS

Therapeutic failure at days 7 and 30 occurred in 8.2% (25/306) and 13.4% (41/306) of patients. Hospital-acquired BSI (adjusted OR [aOR]: 4.10; 95% confidence interval [CI]: 1.50-11.20) and Pitt score (aOR: 1.47; 95% CI: 1.21-1.77) were independently associated with therapeutic failure at day 7. Age-adjusted Charlson Index (aOR: 1.25; 95% CI: 1.05-1.48), Pitt score (aOR: 1.72; 95% CI: 1.35-2.17), and lymphocyte count ≤500 cells/μL at presentation (aOR: 3.16; 95% CI: 1.42-7.06) predicted therapeutic failure at day 30. Carbapenem monotherapy (68.6%, primarily meropenem) was the most frequent active therapy, followed by BLBLI monotherapy (10.8%, mostly piperacillin-tazobactam). Propensity score (PS)-adjusted models revealed no significant impact of the choice of active therapy (carbapenem-containing vs any other regimen, BLBLI- vs carbapenem-based monotherapy) within the first 72 hours on any of the study outcomes.

CONCLUSIONS

Our data suggest that active therapy based on BLBLI may be as effective as carbapenem-containing regimens for ESBL-E BSI secondary to UTI in the specific population of KTR. Potential residual confounding and unpowered sample size cannot be excluded (ClinicalTrials.gov identifier: NCT02852902).

Stewardship program on carbapenem prescriptions in a tertiary hospital for adults and children in France: a cohort study

Antimicrobial stewardship programs aim at reducing the overuse of broad-spectrum antibiotics such as carbapenems, but their impact remains unclear. We compared the use of carbapenems between paediatric and adult subjects admitted to a French tertiary hospital and described the intervention of an antibiotic stewardship team (AST). As part of AST routine activity, all adult and paediatric patients receiving carbapenems are identified in real time using a computer-generated alert system and reviewed by the AST. Data associated with carbapenem prescriptions were extracted for 2 years (2014-2015) and were compared between paediatric and adult wards. Prescription appropriateness (i.e. no clinically suitable narrower spectrum alternative to carbapenem for de-escalation) and AST intervention were analysed. In total, 775 carbapenem prescriptions for 291 children and 262 adults were included. Most patients (95%) had a comordity and 52% had known recent carriage of extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBLE). Most carbapenem prescriptions came from intensive care units (n = 269, 35%) and were initiated for urinary tract (n = 200, 27%), sepsis (n = 181, 25%), and lung (n = 153, 21%) infections. Carbapenems were initiated empirically in 537 (70%) cases, and an organism was isolated in 523 (67%) cases. Among the isolated organisms, 47% (n = 246) were ESBLE and 90% (n = 468) were susceptible to carbapenems, but an alternative existed in 61% (n = 320) of cases according to antibiotic susceptibility testing. Among prescriptions reviewed by the AST, 39% (n = 255) were considered non-appropriate and led to either antibiotic discontinuation (n = 47, 7%) or de-escalation (n = 208, 32%). Non-appropriate prescriptions were more frequent in paediatric wards (p = 0.01) and in microbiologically documented infections (p = 0.013), and less observed in immunocompromised patients (p = 0.009) or with a known ESBLE carriage (p < 0.001). Tailored stewardship programs are essential to better control carbapenem use and subsequent antimicrobial resistance.

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020)

The Japanese Clinical Practice Guidelines for Management of Sepsis and Septic Shock 2020 (J-SSCG 2020), a Japanese-specific set of clinical practice guidelines for sepsis and septic shock created as revised from J-SSCG 2016 jointly by the Japanese Society of Intensive Care Medicine and the Japanese Association for Acute Medicine, was first released in September 2020 and published in February 2021. An English-language version of these guidelines was created based on the contents of the original Japanese-language version. The purpose of this guideline is to assist medical staff in making appropriate decisions to improve the prognosis of patients undergoing treatment for sepsis and septic shock. We aimed to provide high-quality guidelines that are easy to use and understand for specialists, general clinicians, and multidisciplinary medical professionals. J-SSCG 2016 took up new subjects that were not present in SSCG 2016 (e.g., ICU-acquired weakness [ICU-AW], post-intensive care syndrome [PICS], and body temperature management). The J-SSCG 2020 covered a total of 22 areas with four additional new areas (patient- and family-centered care, sepsis treatment system, neuro-intensive treatment, and stress ulcers). A total of 118 important clinical issues (clinical questions, CQs) were extracted regardless of the presence or absence of evidence. These CQs also include those that have been given particular focus within Japan. This is a large-scale guideline covering multiple fields; thus, in addition to the 25 committee members, we had the participation and support of a total of 226 members who are professionals (physicians, nurses, physiotherapists, clinical engineers, and pharmacists) and medical workers with a history of sepsis or critical illness. The GRADE method was adopted for making recommendations, and the modified Delphi method was used to determine recommendations by voting from all committee members. As a result, 79 GRADE-based recommendations, 5 Good Practice Statements (GPS), 18 expert consensuses, 27 answers to background questions (BQs), and summaries of definitions and diagnosis of sepsis were created as responses to 118 CQs. We also incorporated visual information for each CQ according to the time course of treatment, and we will also distribute this as an app. The J-SSCG 2020 is expected to be widely used as a useful bedside guideline in the field of sepsis treatment both in Japan and overseas involving multiple disciplines.

The impact of nephrostomy drainage prior to mini-percutaneous nephrolithotomy in patients with ESBL-positive Escherichia coli

OBJECTIVE

Extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) is one of the most frightening multidrug-resistant bacteria that usually causes sepsis. Herein we explored the benefits of nephrostomy drainage prior to percutaneous nephrolithotomy (PCNL) on infection outcomes in patients with ESBL-EC.

PATIENTS AND METHODS

Between June 2016 and April 2019, 43 consecutive patients with ESBL-EC who received nephrostomy drainage for > 24 h prior to PCNL were retrospectively evaluated as group 1. 86 patients were randomly selected from patients with ESBL-EC who received concurrent percutaneous access during PCNL as group 2. The postoperative infection complications were compared.

RESULTS

Although the total infection complications were not statistically different (11.6% vs. 25.6%, p = 0.066), the severity seemed to be worse among group 2 subjects. Severe infections, including urosepsis (4.7% vs.13.9%) and septic shock (2.3% vs 4.6%), were observed at twice or greater rates in group 2. Blood transfusions were also more frequent (2.3% vs. 13.9%, p = 0.039). Multivariate analysis demonstrated that preoperative drainage was an independent risk factor for postoperative infection events (OR 2.31 CI 1.14-3.48, p = 0.017). Subgroup analyses indicated that preoperative drainage may largely reduce the incidence of urosepsis in patients with hydronephrosis or without receiving preoperative carbapenem therapy.

CONCLUSION

Because of the high rate of severe infection after PCNL in patients with ESBL‑positive E. coli, preoperative nephrostomy drainage for > 24 h is an effective measure to reduce the risk of severe infection complications, especially in patients with hydronephrosis or those without preoperative carbapenem therapy.

Ceftolozane-Tazobactam Treatment of Hypervirulent Multidrug Resistant Pseudomonas aeruginosa Infections in Neutropenic Patients

The effectiveness of ceftolozane/tazobactam for the treatment of infections in neutropenic patients caused by hypervirulent multidrug-resistant (MDR) Pseudomonas aeruginosa has not been previously reported. We identified seven cases of MDR P. aeruginosa infection in neutropenic patients over a four-month period within the same hematology ward. Four cases were associated with rapid progression despite piperacillin-tazobactam or meropenem therapy, and three patients developed sepsis or extensive skin/soft tissue necrosis. In three of the four cases, patients were empirically switched from meropenem to ceftolozane/avibactam before carbapenem susceptibility test results were available, and all four patients underwent extensive surgical debridement or amputation of affected tissues and survived. Further investigation revealed a common bathroom source of MDR P. aeruginosa clonal subtypes ST175 and ST235 that harbored genes for type III secretion system expression and elaboration of ExoU or ExoS exotoxin. We conclude that ceftolozane/tazobactam plus early source control was critical for control of rapidly progressing skin and soft infection in these neutropenic patients caused by highly virulent ST175 and ST235 clones of MDR P. aeruginosa.

Clinical impact of cefepime breakpoint in patients with carbapenem-resistant Klebsiella pneumoniae bacteraemia

The application of cefepime breakpoint for carbapenem-resistant Klebsiella pneumoniae (CRKP) bacteraemia has not been explored. Adult cases of monomicrobial bloodstream infection (BSI) caused by cefepime-susceptible [minimum inhibitory concentration (MIC) ≤8 mg/L] K. pneumoniae isolates with carbapenem resistance between 2010 and 2015 were reviewed. Patients treated with cefepime were compared with those treated by other active agents using a propensity score-matched analysis to assess therapeutic effectiveness. The primary endpoint was 30-day crude mortality. A total of 114 patients experienced cefepime-susceptible CRKP bacteraemia and 40 (35.1%) died during hospitalisation. A total of 33 patients (28.9%) received cefepime therapy. Fifteen patients (13.2%) had BSI due to carbapenemase-producing isolates, and 86.7% (13/15) of carbapenemase-producing isolates were classified as cefepime susceptible dose-dependent (SDD). In the multivariate logistic regression analysis, 30-day mortality was independently associated with the presence of a critical illness [adjusted odds ratio (aOR) = 12.89, 95% confidence interval (CI) 3.88-42.83; P < 0.001], pneumonia (aOR = 5.97, 95% CI 1.65-21.76; P = 0.007) and rapidly fatal underlying disease (aOR = 6.43, 95% CI 1.30-31.09; P = 0.02). In contrast, cefepime-based therapy (aOR = 0.03, 95% CI 0.003-0.38; P = 0.006) and combination therapy (aOR = 0.09, 95% CI 0.02-0.36; P = 0.001) were protective against a fatal outcome. Based on current breakpoints for Enterobacterales, cefepime therapy was not associated with an unfavourable outcome for CRKP BSI with MIC-based dosing strategies. However, the susceptibility result of SDD to cefepime should alert clinicians for possible therapeutic failure.

Efflux Pump AcrAB Confers Decreased Susceptibility to Piperacillin-Tazobactam and Ceftolozane-Tazobactam in Tigecycline-Non-Susceptible Klebsiella pneumoniae

Introduction

Drug efflux pumps are critical for resistance in Gram-negative organisms, but there are limited data on the role they play in decreased susceptibility to β-lactam/β-lactamase inhibitor combinations. In this study, we aimed to investigate the impact of efflux pump AcrAB on piperacillin–tazobactam (TZP) and ceftolozane–tazobactam (C/T) susceptibility in tigecycline-non-susceptible Klebsiella pneumoniae (TNSKP) strains.

Methods

A tigecycline gradient was used to obtain various TNSKP strains, and in conjunction with the gradient derived strains, a TNSKP clinical strain (TNSKP24) was also included. Minimum inhibitory concentrations (MICs) of antibiotics were determined by the broth microdilution method, and whole-genome sequencing (WGS) was carried out to analyze genomic changes. PCR and sequencing were performed to confirm mutations in ramR, acrR, and the intergenic region of ramR-romA, and qRT-PCR was applied to evaluate levels of gene expression. In-frame acrB knockout and complementation were performed in 3 TNSKP strains.

Results

Two derivatives of K. pneumoniae K2606 (K2606-4 and K2606-16) and TNSKP24 overexpressed efflux pump AcrAB were obtained for further study. The MICs of TZP and C/T exhibited a 4- to 8-fold increase in K2606-4 and K2606-16, respectively, when compared with K2606 (TZP, 2/4 μg/mL; C/T, 0.25/4 μg/mL). Deletion of acrB decreased the MICs of TZP and C/T by 4- to 16-fold in TNSKP24, K2606-4, and K2606-16, respectively, and complementation of acrB increased the MICs of these agents. MICs of clavulanate, sulbactam, and avibactam in the presence of β-lactam compounds did not change after acrB deletion and subsequent introduction of complementation mutants.

Conclusion

This study highlights that decreased susceptibility to TZP and C/T could be caused by the multidrug efflux pump AcrAB in TNSKP strains.

Is Piperacillin-Tazobactam Effective for the Treatment of Pyelonephritis Caused by Extended-Spectrum β-Lactamase-Producing Organisms?

BACKGROUND

Limited data exist regarding the efficacy of piperacillin-tazobactam (TZP) for the management of nonbacteremic pyelonephritis caused by extended-spectrum β-lactamase (ESBL)-producing organisms.

METHODS

We conducted a multicenter observational study comparing clinical outcomes of adults hospitalized with ESBL-producing pyelonephritis who were receiving TZP versus carbapenems, using an inverse probability of treatment weighted propensity score analysis. Patients were eligible for inclusion if all of the following criteria were met: (1) urine cultures growing Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, or Proteus mirabilis at ≥50 000 colony-forming units/mL; (2) identification of an ESBL gene; (3) pyuria (≥10 white blood cells per high powered field in the urine); and (4) dysuria and fever plus at least 1 of the following symptoms: emesis, rigors, hypotension, or flank pain.

RESULTS

There were 186 patients included in the propensity score-weighted cohort; 45 (24%) received TZP and 141 (76%) received a carbapenem. Of these 186 patients, 27% were admitted to the intensive care unit, 48% were immunocompromised, and 45% had underlying urologic abnormalities. There were no differences between the 2 groups in the proportion of patients (20% vs 25%) with recurrent cystitis or pyelonephritis with the same ESBL-producing organism within 30 days (odds ratio, 0.75; 95% confidence interval, .31-1.81; P = .52). There were no differences in the resolution of clinical symptoms by Day 7 or in 30-day mortality. There was 1 (2%) patient in the TZP arm and 11 (8%) patients in the carbapenem arm who had incident carbapenem-resistant organisms isolated within 30 days (P = .09).

CONCLUSIONS

TZP may be a reasonable alternative to carbapenems for the management of ESBL-producing pyelonephritis and may mitigate the risk of emergence of carbapenem-resistant organisms, compared with carbapenem therapy.

Carbapenem-sparing strategy: carbapenemase, treatment, and stewardship

PURPOSE OF REVIEW

describing the current role of carbapenems and carbapenem-sparing strategies in the setting of antimicrobial stewardship programs.

RECENT FINDINGS

sparing carbapenems with other drugs appears to be an interesting perspective for a variety of reasons in the current context of the multidrug-resistant (MDR) pandemic. Specific algorithms should also be precisely investigated to define better how to spare carbapenems within empiric and targeted regimens, with combination treatment or monotherapies, aiming at the best use of the new drugs and improving de-escalation as soon as possible for most of the patients.

SUMMARY

stewardship programs may be useful in reducing probable misuse and overuse of antibiotics, which has probably contributed to the emergence of carbapenem-resistant bacteria worldwide. The proposal of carbapenem-sparing strategies has then generated substantial scientific debate and, overall, the concept of sparing these drugs is well advocated together with judicious use of novel drugs, appropriate measures of infection control and prevention as well as in stewardship programs to curb the spread of MDR and XDR-strains in healthcare facilities.

Development and validation of a scoring system for predicting cancer patients at risk of extended-spectrum b-lactamase-producing Enterobacteriaceae infections

Background

Extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBL-PE) infections are frequent and highly impact cancer patients. We developed and validated a scoring system to identify cancer patients harboring ESBL-PE at the National Institute of Cancer of Colombia.

Methods

We retrospectively analyzed medical records of 1695 cancer patients. Derivation phase included 710 patients admitted between 2013 to 2015, ESBL-PE positive culture (n = 265) paired by month and hospitalization ward with Non-ESBL-PE (n = 445). A crude and weighted score was developed by conditional logistic regression. The model was evaluated in a Validation cohort (n = 985) with the same eligibility criteria between 2016 to 2017.

Results

The score was based on eight variables (reported with Odds Ratio and 95% confidence interval): Hospitalization ≥7 days (5.39 [2.46–11.80]), Hospitalization during the previous year (4, 87 [2.99–7.93]), immunosuppressive therapy during the previous 3 months (2.97 [1.44–6.08]), Neutropenia (1.90 [1.12–3.24]), Exposure to Betalactams during previous month (1.61 [1.06–2.42]), Invasive devices (1.51 [1.012–2.25]), Neoplasia in remission (2.78 [1.25–1.17]), No chemotherapy during the previous 3 months (1.90 [1.22–2.97]). The model demonstrated an acceptable discriminatory capacity in the Derivation phase, but poor in the Validation phase (Recipient Operating Characteristic Curve: 0.68 and 0.55 respectively).

Conclusions

Cancer patients have a high prevalence of risk factors for ESBL-PE infection. The scoring system did not adequately discriminate patients with ESBL-PE. In a high-risk population, other strategies should be sought to identify patients at risk of resistant ESBL-PE infection.

Pharmacotherapeutic advances for recurrent urinary tract infections in women

INTRODUCTION

Treatment of recurrent Urinary tract infections (UTIs) has become challenging because of the dramatic increase in the rates of recurrent infection andof multidrug-resistant (MDR) infections.

AREAS COVERED

The authors review recurrent UTIs(rUTI) management in women.

EXPERT OPINION

Continuous or post-coital prophylaxis with low-dose antimicrobials or intermittent self-treatment has all been demonstrated to be effective in managing rUTIs in women. Intravaginal estrogen therapy , shows potential toward preventing rUTI. Oral vaccine Uro-Vaxom seems to reduce the number of UTIs. There is evidence that other therapies (e.g. cranberry, Methenamine hippurate, oral D-mannose) may decrease the number of symptomatic UTIs. The treatment of CRE-UTIs is focused on a colistin backbone. Carbapenems are considered first-line agents for UTIs caused by ESBL, but their use is associated with increased MDR. The usage of non-carbapenem for the treatment of ESBL UTIs is necessary. Cefepime, Piperacillin-Tazobactam, Ceftolozane-Tazobactam, and Ceftazidime-Avibactam are justified options. Oral therapy with Pivmecillinam, Fosfomycin, and Nitrofurantoin can be used against uncomplicated UTIs due to ESBL infection.

Ecofriendly Biomolecule-Capped Bifidobacterium bifidum-Manufactured Silver Nanoparticles and Efflux Pump Genes Expression Alteration in Klebsiella pneumoniae

Background: Klebsiella pneumoniae is currently considered as an immediate threat to human health due to its various multidrug efflux pumps. Microbially synthesized silver nanoparticles (AgNPs) are an attractive and eco-friendly approach to prevent antibiotic resistance in bacteria. In the present study, we compared the inhibitory effect of both commercial and green AgNPs by Bifidobacterium bifidum on OxqAB efflux pump genes in ciprofloxacin-resistant strains of K. pneumoniae. Materials and Methods: AgNPs were characterized by ultraviolet-visible spectrophotometer, Fourier transform infrared spectroscopy, X-ray diffraction, zeta potential, transmission electron microscopy, and scanning electron microscopy. Antibiogram was used to identify resistant isolates and the effect of the biosynthesized AgNPs against OxqAB efflux pump strains was assessed by the minimum inhibitory concentration (MIC) method. The expression levels of oxqAB genes were evaluated using real-time polymerase chain reaction (PCR) followed by exposure to subMICs of the AgNPs. Results: PCR results showed that 25 strains had OxqAB efflux pump and the MIC method indicated that AgNPs had an inhibitory effect on all resistant strains with OxqAB efflux pump. The efficacy of the synthetic nanoparticles was assessed by comparing the antiefflux pump activity with commercial AgNPs. In ciprofloxacin-resistant isolates, the oxqAB genes expression levels reduced in the subMIC of both AgNPs, whereas biosynthesized AgNPs had greater bactericidal effects compared with the commercial AgNPs. Conclusions: Efflux pumps could be an attractive target for our biosynthesized AgNPs. The oxqAB genes expression levels reduced in subMIC of both AgNPs, whereas biosynthesized AgNPs had greater bactericidal effects than the commercial AgNPs.

Pharmacokinetics-Pharmacodynamics of Enmetazobactam Combined with Cefepime in a Neutropenic Murine Thigh Infection Model

Third-generation cephalosporin (3GC)-resistant Enterobacteriaceae are classified as critical priority pathogens, with extended-spectrum β-lactamases (ESBLs) as principal resistance determinants. Enmetazobactam (formerly AAI101) is a novel ESBL inhibitor developed in combination with cefepime for empirical treatment of serious Gram-negative infections in settings where ESBLs are prevalent. Cefepime-enmetazobactam has been investigated in a phase 3 trial in patients with complicated urinary tract infections or acute pyelonephritis. This study examined pharmacokinetic-pharmacodynamic (PK-PD) relationships of enmetazobactam, in combination with cefepime, for ESBL-producing isolates of Klebsiella pneumoniae in 26-h murine neutropenic thigh infection models. Enmetazobactam dose fractionation identified the time above a free threshold concentration (fT > C_T ) as the PK-PD index predictive of efficacy. Nine ESBL-producing isolates of K. pneumoniae, resistant to cefepime and piperacillin-tazobactam, were included in enmetazobactam dose-ranging studies. The isolates encoded CTX-M-type, SHV-12, DHA-1, and OXA-48 β-lactamases and covered a cefepime-enmetazobactam MIC range from 0.06 to 2 μg/ml. Enmetazobactam restored the efficacy of cefepime against all isolates tested. Sigmoid curve fitting across the combined set of isolates identified enmetazobactam PK-PD targets for stasis and for a 1-log₁₀ bioburden reduction of 8% and 44% fT > 2 μg/ml, respectively, with a concomitant cefepime PK-PD target of 40 to 60% fT > cefepime-enmetazobactam MIC. These findings support clinical dose selection and breakpoint setting for cefepime-enmetazobactam.

Fourth Generation Cephalosporin Resistance Among Salmonella enterica Serovar Enteritidis Isolates in Shanghai, China Conferred by bla CTX-M-55 Harboring Plasmids

In this study, we investigated the pattern of antimicrobial resistance in Salmonella enterica serotype Enteritidis isolates in Shanghai, China from 2005 to 2014. We found the first isolates with resistance to the fourth-generation cephalosporin cefepime starting in 2010. Furthermore, we analyzed the epidemic characteristics and mechanisms of underlying cefepime resistance in S. Enteritidis isolates found from 2010. In total, 38 of 2,914 (1.30%) isolates were identified as cefepime-resistant S. Enteritidis (CRSE) isolates by Kirby-Bauer disk diffusion. Two isolates were from animal derived food sources; 36 isolates were from fecal samples of human patients with salmonellosis. Antimicrobial susceptibility testing using the agar dilution method revealed that all CRSE isolates showed additional resistances at least to ceftazidime, cefotaxime, and ampicillin. Additionally, pulsed-field gel electrophoresis (PFGE) profiles indicated that 89.47% of CRSE isolates also displayed similar PFGE patterns. Five types of β-lactamase genes, bla _CTX-M (100.00%, 38/38), bla _SHV (65.79%, 25/38), bla _TEM (52.63%, 20/38), bla _ACC (18.42%, 7/38), and bla _PSE (5.26%, 2/38) were detected by PCR and sequencing. Among bla _CTX-M genes, bla _CTX-M-55 was the dominant type (84.21%, 32/38). Conjugation and transformation experiments along with plasmid replicon typing revealed that bla _CTX-M-55 was located on plasmids of various replicon types with sizes ranging from 76.8 to 138.9 kb. Plasmid sequence analysis also showed that the bla _CTX-M-55 gene was mobilized mainly by the ISEcp1-bla _CTX-M-55-ORF477 transposition unit and had its own ISEcp1-based promoter, which accelerated the expression and transmission of bla _CTX-M-55. Analysis of whole genome sequences (Illumina) of one selected transformant SH12G706-C showed high similarity of the bla _CTX-M-55 carrying plasmid with the IncI1 plasmid backbone p628-CTX-M of Klebsiella pneumoniae detected in 2010 in China. The present study demonstrated that the bla _CTX-M-55 gene mobilized by ISEcp1- bla _CTX-M-55-ORF477 was the main feature shared by CRSE isolates and seems to play an important role for transmission of cefepime resistance. The number of CRSE isolates is rising annually, and the strong dissemination ability of ISEcp1-bla _CTX-M-55-ORF477-harboring plasmids among different species represents an important threat to the therapeutic effectiveness of cefepime.

Plazomicin: an intravenous aminoglycoside antibacterial for the treatment of complicated urinary tract infections

INTRODUCTION

Antimicrobial resistance continues to be a major public health concern due to the emergence and spread of multi-drug resistant (MDR) organisms, including extended spectrum ß-lactamase (ESBL) and carbapenemase producing Enterobacterales. Plazomicin is a novel aminoglycoside that demonstrates activity against MDR gram-negatives, including those producing ESBLs and most carbapenemases, and retains activity against aminoglycoside modifying enzymes as a result of structural modifications. The information discussed is meant to assist in identifying plazomicin's place in therapy and to expand the clinician's armamentarium.

AREAS COVERED

Herein, we review the pharmacology, microbiology, clinical efficacy, and safety of plazomicin. To gather relevant information, a literature search was performed using PubMed, Ovid, and Google Scholar electronic databases. Search terms used include plazomicin, ACHN-490, extended spectrum ß-lactamase, ESBL, CRE, aminoglycoside modifying enzymes, and AME. Additional information was obtained from FDA review documents and research abstracts presented at international conferences.

EXPERT OPINION

Plazomicin is a promising carbapenem or β-lactam/β-lactamase inhibitor-sparing alternative for the treatment of complicated urinary tract infections caused by MDR Enterobacterales. Although robust data for bloodstream infections and bacterial pneumonias are lacking, plazomicin may be considered in individual clinical scenarios if combination therapy is warranted provided supportive microbiological data and therapeutic drug monitoring are available.

OXA-1 β-lactamase and non-susceptibility to penicillin/β-lactamase inhibitor combinations among ESBL-producing Escherichia coli

Background

ESBL-producing Escherichia coli have expanded globally since the turn of the century and present a major public health issue. Their in vitro susceptibility to penicillin/inhibitor combinations is variable, and clinical use of these combinations against ESBL producers remains controversial. We hypothesized that this variability related to co-production of OXA-1 penicillinase.

Methods

During a national study we collected 293 ESBL-producing E. coli from bacteraemias, determined MICs by BSAC agar dilution, and undertook genomic sequencing with Illumina methodology.

Results

The collection was dominated by ST131 (n = 188 isolates, 64.2%) and blaCTX-M-15 (present in 229 isolates, 78.2%); over half the isolates (159/293, 54.3%) were ST131 with blaCTX-M-15. blaOXA-1 was found in 149 ESBL producers (50.9%) and blaTEM-1/191 in 137 (46.8%). Irrespective of whether all isolates were considered, or ST131 alone, there were strong associations (P < 0.001) between co-carriage of blaOXA-1 and reduced susceptibility to penicillin/inhibitor combinations, whereas there was no significant association with co-carriage of blaTEM-1/191. For piperacillin/tazobactam the modal MIC rose from 2 mg/L in the absence of blaOXA-1 to 8 or 16 mg/L in its presence; for co-amoxiclav the shift was smaller, from 4 or 8 to 16 mg/L, but crossed the breakpoint. blaOXA-1 was strongly associated with co-carriage also of aac(6')-Ib-cr, which compromises amikacin and tobramycin.

Conclusions

Co-carriage of OXA-1, a penicillinase with weak affinity for inhibitors, is a major correlate of resistance to piperacillin/tazobactam and co-amoxiclav in E. coli and is commonly associated with co-carriage of aac(6')-Ib-cr, which narrows aminoglycoside options.

Clinical Experience with Ceftazidime-Avibactam for the Treatment of Infections due to Multidrug-Resistant Gram-Negative Bacteria Other than Carbapenem-Resistant Enterobacterales

BACKGROUND

Experience in real clinical practice with ceftazidime-avibactam for the treatment of serious infections due to gram-negative bacteria (GNB) other than carbapenem-resistant Enterobacterales (CRE) is very limited.

METHODS

We carried out a retrospective multicenter study of patients hospitalized in 13 Italian hospitals who received ≤72 h of ceftazidime-avibactam for GNB other than CRE to assess the rates of clinical success, resistance development, and occurrence of adverse events.

RESULTS

Ceftazidime-avibactam was used to treat 41 patients with GNB infections other than CRE. Median age was 62 years and 68% of them were male. The main causative agents were P. aeruginosa (33/41; 80.5%) and extended spectrum beta lactamase (ESBL)-producing Enterobacterales (4/41, 9.8%). Four patients had polymicrobial infections. All strains were susceptible to ceftazidime-avibactam. The most common primary infection was nosocomial pneumonia (n = 20; 48.8%), primary bacteremia (n = 7; 17.1%), intra-abdominal infection (n = 4; 9.8%), and bone infection (n = 4; 9.8%). Ceftazidime-avibactam was mainly administered as a combination treatment (n = 33; 80.5%) and the median length of therapy was 13 days. Clinical success at the end of the follow-up period was 90.5%, and the only risk factor for treatment failure at multivariate analysis was receiving continuous renal replacement therapy during ceftazidime-avibactam. There was no association between clinical failures and type of primary infection, microbiological isolates, and monotherapy with ceftazidime-avibactam. Only one patient experienced recurrent infection 5 days after the end of treatment. Development of resistance to ceftazidime-avibactam was not detected in any case during the whole follow-up period. No adverse events related to ceftazidime-avibactam were observed in the study population.

CONCLUSIONS

Ceftazidime-avibactam may be a valuable therapeutic option for serious infections due to GNB other than CRE.

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).

Machine Learning and Multidrug-Resistant Gram-Negative Bacteria: An Interesting Combination for Current and Future Research

The dissemination of multidrug-resistant Gram-negative bacteria (MDR-GNB) is associated with increased morbidity and mortality in several countries. Machine learning (ML) is a branch of artificial intelligence that consists of conferring on computers the ability to learn from data. In this narrative review, we discuss three existing examples of the application of ML algorithms for assessing three different types of risk: (i) the risk of developing a MDR-GNB infection, (ii) the risk of MDR-GNB etiology in patients with an already clinically evident infection, and (iii) the risk of anticipating the emergence of MDR in GNB through the misuse of antibiotics. In the next few years, we expect to witness an increasingly large number of research studies perfecting the application of ML techniques in the field of MDR-GNB infections. Very importantly, this cannot be separated from the availability of a continuously refined and updated ethical framework allowing an appropriate use of the large datasets of medical data needed to build efficient ML-based support systems that could be shared through appropriate standard infrastructures.

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.

Evaluation of the in vitro activity of WCK 5222 (cefepime/zidebactam) and currently available combination therapies against single- and double-carbapenemase producing Enterobacteriaceae: Expanding the zone of hope

Cefepime/zidebactam (WCK 5222) is a β-lactam/β-lactam enhancer antibiotic designed to retain in vitro activity against Enterobacteriaceae that simultaneously produce metallo-β-lactamase (MBL) and serine-β-lactamase (SBL). Aztreonam (ATM) plus ceftazidime/avibactam (CZA) or meropenem/vaborbactam (M/V) is an attractive option for coverage of such strains, but clinical laboratories are not equipped to distinguish which is the more potent regimen to inform treatment decisions. We evaluated Enterobacteriaceae that expressed MBL and ≥1 SBL (n=15) using gradient diffusion strip (GDS) methods to (1) determine the minimum inhibitory concentration (MIC) of WCK 5222 and (2) compare the in vitro potency of CZA+ATM vs. M/V+ATM. All isolates were non-susceptible to ATM, CZA, and M/V and were inhibited by WCK 5222 at cefepime concentrations ≥2 log₂ dilutions below the susceptible-dose dependent breakpoint of 8 mg/L (MIC_50/90, 1/2 mg/L). Activity of CZA+ATM vs. M/V+ATM was compared using the zone of hope (ZOH) product, quantitated by multiplying the length (in mm) of inhibited growth adjacent to each GDS from the point of intersection. The median (interquartile range) ZOH product for CZA+ATM and M/V+ATM was 75.4 (62.8-93.7) and 23.5 (14.1-60.4), respectively (P=0.002). In strains with one carbapenemase (the MBL), the median ZOH products were not statistically different, but in strains with an OXA-type carbapenemase (n=6), the median product for CZA+ATM and M/V+ATM was 78.1 and 20.7, respectively (P=0.004). Thus, CZA+ATM may offer enhanced coverage over M/V+ATM of Enterobacteriaceae co-expressing MBL and SBL. Further preclinical in vivo evaluations of WCK 5222 monotherapy are warranted.

In vitro activity of ceftolozane/tazobactam against phenotypically defined extended-spectrum β-lactamase (ESBL)-positive isolates of Escherichia coli and Klebsiella pneumoniae isolated from hospitalized patients (SMART 2016)

The Clinical and Laboratory Standards Institute (CLSI)-defined broth microdilution testing method (M07, 11th edition, 2018) was used to determine MICs for ceftolozane/tazobactam and eight comparator agents against 21,952 isolates of Enterobacteriaceae submitted by 161 clinical laboratories in 51 countries in 2016 as a part of the SMART global surveillance program. MICs were interpreted using CLSI breakpoints (M100 29th edition, 2019). 89.7% of isolates of Enterobacteriaceae were susceptible to ceftolozane/tazobactam, compared to 70.0%, 76.3%, 77.7%, 84.7%, 93.6%, and 96.4%, respectively, for ceftriaxone, ceftazidime, cefepime, piperacillin-tazobactam, ertapenem, and meropenem. 82.4% of isolates of ESBL-positive, carbapenemase-negative Enterobacteriaceae were susceptible to ceftolozane/tazobactam, compared to 1.5%, 7.8%, 20.3%, 71.1%, 94.7%, and 98.7%, respectively, for ceftriaxone, cefepime, ceftazidime, piperacillin-tazobactam, ertapenem, and meropenem. In vitro susceptibility to ceftolozane/tazobactam was >60% higher than susceptibility to other advanced-generation cephalosporins among all Enterobacteriaceae and >10% higher than susceptibility to piperacillin-tazobactam among ESBL-positive Enterobacteriaceae collected globally in 2016.

Challenges and research priorities to progress the impact of antimicrobial stewardship

Antimicrobial stewardship programmes have been playing an important role in patient care and hospital policies. These programmes are now recognised as formal strategies for curbing the upward trend in antibiotic resistance and for improving the appropriate antimicrobial and antifungal use. The role of such programs in the era of antimicrobial resistance presents several unique challenges and opportunities, most notably in the diagnostic and therapeutic setting. Controversies remain regarding the most effective interventions and the appropriate design to evaluate their impact. In this review, based on rounds of discussion, we explain the most important challenges faced by antibiotic stewardship and antifungal stewardship programmes. We also try to suggest areas for further research.

Development of Broth Microdilution MIC and Disk Diffusion Antimicrobial Susceptibility Test Quality Control Ranges for the Combination of Cefepime and the Novel β-Lactamase Inhibitor Enmetazobactam

Third-generation cephalosporin resistance among Enterobacteriaceae, mediated by the spread of extended-spectrum β-lactamases (ESBLs), is a very serious medical concern with limited therapeutic options. Enmetazobactam (formerly AAI101) is a novel penicillanic sulfone β-lactamase inhibitor active against a wide range of ESBLs. The combination of enmetazobactam and cefepime has entered phase 3 development in patients with complicated urinary tract infections. Using the Clinical and Laboratory Standards Institute (CLSI) M23 tier 2 study design, broth microdilution MIC and disk diffusion quality control (QC) ranges were determined for cefepime-enmetazobactam. Enmetazobactam was tested at a fixed concentration of 8 μg/ml in the MIC assay, and a cefepime-enmetazobactam disk mass of 30/20 μg was used in the disk diffusion assay. Escherichia coli ATCC 25922, E. coli ATCC 35218, E. coli NCTC 13353, Klebsiella pneumoniae ATCC 700603, and Pseudomonas aeruginosa ATCC 27853 were chosen as reference strains. The CTX-M-15-producing E. coli NCTC 13353 isolate is recommended for routine testing to control for inhibition of ESBL activity by enmetazobactam. Broth microdilution MIC QC ranges spanned 3 to 4 doubling dilutions and contained 99.6% to 100.0% of obtained MIC values for the five reference strains. Disk diffusion yielded inhibition zone diameter QC ranges that spanned 7 mm and encompassed 97.1% to 100.0% of the obtained values. Quality control ranges were approved by the CLSI in 2017 (broth microdilution MIC) and 2019 (disk diffusion). The established QC ranges will ensure that appropriate assay performance criteria are attained using CLSI reference methodology when determining the susceptibility of clinical isolates to cefepime-enmetazobactam.

Clinical cure rate and cost-effectiveness of carbapenem-sparing beta-lactams vs. meropenem for Gram-negative infections: A systematic review, meta-analysis, and cost-effectiveness analysis

The increasing incidence of infections caused by extended-spectrum beta-lactamase (ESBL)/AmpC-producing bacteria leads to increasing use of carbapenems and risk of carbapenem resistance. Treatment success of carbapenem-sparing beta-lactams (CSBs) for ESBL infections is unclear. The aim of this study was to appraise the clinical cure rate and estimate the cost-effectiveness of meropenem vs. CSBs (piperacillin-tazobactam, temocillin, ceftazidime-avibactam, and ceftolozane-tazobactam) for urinary tract infections (UTIs) or intra-abdominal infections (IAIs) due to ESBL/AmpC-producing bacteria. A systematic literature search of the Cochrane library, EMBASE, PubMed, and Web of Science was conducted to identify studies assessing the clinical cure rate of the antibiotics. To assess the cost-effectiveness of CSBs vs. meropenem, a combined decision analytic and Markov model was probabilistically analysed over a 5-year period. The main outcome was presented as the incremental cost-effectiveness ratio and evaluated with a threshold of €20 000 per life year gained (LYG). From 656 identified articles, 17 and 14 studies were included in the qualitative synthesis and quantitative synthesis, respectively. A clinical cure of ceftazidime-avibactam and ceftolozane-tazobactam was comparable to meropenem in patients with complicated IAIs (cIAIs) due to ESBL (Risk ratio [RR]=1·04, 95% confidence interval [CI]=0·95-1·13). Both temocillin and ceftolozane-tazobactam were deemed cost-effective compared to meropenem with €157·58 and €13 398·34 per LYG, respectively, in patients with UTIs due to ESBL. However, only ceftazidime-avibactam (plus metronidazole) was cost-effective for the treatment of IAIs, with €16 916·77 per LYG. These results show that several CSBs can be considered as viable candidates for the treatment of UTIs and IAIs caused by ESBL.

Cefmetazole for extended-spectrum β-lactamase-producing Enterobacteriaceae in pediatric pyelonephritis

BACKGROUND

Pyelonephritis caused by extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae is an urgent problem in pediatrics. Although carbapenem is the standard therapy for infections caused by ESBL-producing Enterobacteriaceae, some cephamycins, including cefmetazole, are stable against hydrolysis by ESBL. There are few reports, however, on the use of cefmetazole in children. The aim of this study was to evaluate the therapeutic effect of cefmetazole in pediatric pyelonephritis caused by ESBL-producing Enterobacteriaceae.

METHODS

Children with pyelonephritis caused by ESBL-producing Enterobacteriaceae were enrolled between April 2010 and November 2016 at Tokyo Metropolitan Children's Medical Center. Presence of ESBL was tested for using the disk diffusion method. Medical records were reviewed for a past history of bacterial infection. The outcomes were clinical cure rate at 4 weeks and the duration of therapy in the cefmetazole and non-cefmetazole groups.

RESULTS

Fifty-five patients met the criteria for pyelonephritis caused by ESBL-producing Enterobacteriaceae. The most common causative organisms were Escherichia coli (n = 51; 92.7%), Klebsiella pneumoniae (n = 3; 5.5%), and K. oxytoca (n = 1; 1.8%). Thirty-six and 19 patients were treated with cefmetazole and with other antibiotics as definitive therapy, respectively. There was no difference in the clinical cure rate (86.1% vs 89.5%; P = 0.72) or duration of therapy (median, 7.0 vs 7.0 days; P = 0.73) between the cefmetazole and non-cefmetazole groups.

CONCLUSIONS

Cefmetazole was not inferior to the other antibiotics in the treatment of pyelonephritis caused by ESBL-producing Enterobacteriaceae in children. Cefmetazole is a valuable therapeutic alternative to carbapenems for treating pyelonephritis caused by ESBL-producing Enterobacteriaceae.

In vitro activity of ceftazidime/avibactam against clinical isolates of ESBL-producing Enterobacteriaceae in Italy

Resistance to carbapenems in Enterobacteriaceae is a serious concern for public health. Alternative treatment options involving carbapenem-sparing regimen for patients with serious infections caused by multidrug-resistant Enterobacteriaceae are urgently needed. Ceftazidime/avibactam (CZA) is a new combination of a third generation cephalosporin and a non-β-lactam β-lactamase inhibitor, in which avibactam is capable to expand the ceftazidime activity also against extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae. To date, no data exist regarding the activity of CZA against strains isolated in the Italian context, which is known as endemic for ESBL producers. The aim of this study was to evaluate the in vitro activity of CZA, in comparison to ceftazidime (CAZ), against 90 ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates, collected from blood and urine samples at our Institute. Thus, avibactam has been able to restore the activity of CAZ in all cases, suggesting the potential use of CZA as a carbapenem-sparing model, especially when limited therapeutic options exist.

Derivation and validation of a simple score to predict the presence of bacteria requiring carbapenem treatment in ICU-acquired bloodstream infection and pneumonia: CarbaSCORE

Background

The recommendations of learned societies mention risk factors for the presence of multidrug resistant bacteria in hospital-acquired infections, but they do not propose a scoring system to guide empiric antibiotic therapy. Our study was aimed at developing a simple score for predicting "the presence of bacteria requiring carbapenem treatment" in ICU-acquired bloodstream infection and pneumonia.

Methods

Between December 2011 and January 2015, we conducted a retrospective study using a prospectively collected French database of nosocomial infections in the polyvalent intensive care unit of a French university hospital. All patients with ICU-acquired bloodstream infection or pneumonia were included in the study. Bivariate and multivariate analyses were performed to develop the CarbaSCORE, and this score was internally validated.

Results

In total, 338 patients were analyzed, including 27 patients requiring carbapenem treatment. The CarbaSCORE was composed of four criteria: "presence of bloodstream infection" (as opposed to pneumonia) scored 2 points, "chronic hemodialysis" scored 4 points, "travel abroad in the last 6 months" scored 5 points, and "MDR-colonization or prior use of a β-lactam of class ≥ 3" scored 6 points. Internal validation by bootstrapping showed an area under the receiver operating characteristic curve of 0.81 [0.73-0.89]. Sensitivity was 96% at the 6-point threshold and specificity was 91% at the 9-point threshold.

Conclusions

The CarbaSCORE is a simple and efficient score for predicting the presence of bacteria requiring carbapenem treatment. Further studies are needed to test this score before it can be used in practice.

Does Quick Sepsis-Related Organ Failure Assessment Suggest the Use of Initial Empirical Carbapenem Therapy in Bacteremia Caused by Extended-Spectrum β-Lactamase-Producing Bacteria? :A Multicenter Case-Control Study

We hypothesized that quick Sequential Organ Failure Assessment (qSOFA) would be associated with 30-day mortality in bacteremia caused by extended-spectrum β-lactamase (ESBL)-producing bacteria and might be a selection criterion for the use of carbapenem as initial empirical therapy. A multicenter retrospective study was conducted in six hospitals. All patients who had bacteremia due to ESBL-producing bacteria were included in the study. Multivariable logistic regression analysis was performed to analyze 30-day mortality as the main outcome. A total of 203 adult patients were identified with bacteremia caused by ESBL-producing Escherichia coli, Klebsiella pneumoniae, or Proteus mirabilis. In multivariate logistic regression analysis, bacteremia caused by ESBL-producing K. pneumoniae or P. mirabilis (odds ratio [OR] 5.07, 95% confidence interval [CI] 1.64-15.56), underlying liver disease (OR 3.38, 95% CI 1.09-10.00), and underlying solid cancer (OR 3.45, 95% CI 1.27-9.69) were associated with 30-day mortality. In a subgroup analysis, empirical non-carbapenem therapy was associated with 30-day mortality in bacteremia caused by ESBL-producing K. pneumoniae or P. mirabilis. Our results suggest that the qSOFA score is not a selection criterion for the use of carbapenem in initial empirical therapy.

Current and emerging pharmacotherapy for the treatment of infections following open-heart surgery

INTRODUCTION

Patients undergoing open-heart surgery may suffer from postoperative complications, including severe infections. Antimicrobials to treat infectious complications in this population should be selected thoughtfully, taking into account three different and fundamental issues: (i) the site of infection; (ii) the suspected or proven causative agent and its susceptibility pattern; and (iii) the risk of suboptimal pharmacokinetic characteristics and potential toxicity of the chosen drug/s.

AREAS COVERED

The present narrative review summarizes the current and future antimicrobial options for the treatment of infections developing after open-heart surgery.

EXPERT OPINION

The pharmacological treatment of infections developing in cardiac surgery patients poses peculiar challenges, including the need for an active empirical therapy for severe events such as bloodstream infections, deep sternal wound infections, or early-onset postoperative prosthetic endocarditis. In addition, the risk for multidrug-resistant pathogens should also be taken into account in endemic areas. A multidisciplinary evaluation on a patient-by-patient basis, deeply involving infectious diseases specialists and cardiothoracic surgeons, remains essential for appropriately balancing both short-term and long-term risks and benefits of any possible surgical reintervention in combination with adequate pharmacotherapy.