Carbapenem-Nonsusceptible Gram-Negative Pathogens in ICU and Non-ICU Settings in US Hospitals in 2017: A Multicenter Study

Real-world evaluation of imipenem/cilastatin/relebactam across US medical centres

We assessed 160 patients who received imipenem/cilastatin/relebactam for ≥2 days. At treatment initiation, the median Charlson Comorbidity Index was 5, 45% were in the intensive care unit, and 19% required vasopressor support. The in-hospital mortality rate was 24%. These data advance our understanding of real-world indications and outcomes of imipenem/cilastatin/relebactam use.

Real-world in vitro activity of newer antibiotics against Enterobacterales and Pseudomonas aeruginosa, including carbapenem-non-susceptible and multidrug-resistant isolates: a multicenter analysis

IMPORTANCE

Newer antibiotics against Gram-negative pathogens provide important treatment options, especially for antibiotic-resistant bacteria, but little is known about their use during routine clinical care. To use these agents appropriately, clinicians need to have access to timely susceptibility data. We evaluated 27,531 facility-reported susceptibility results from the BD Insights Research Database to gain a better understanding of real-world testing practices and susceptibility rates for six newer antibiotics. Escherichia coli was the most frequently tested potential pathogen, and ceftazidime-avibactam and ceftolozane-tazobactam had the greatest numbers of susceptibility results. For cefiderocol, eravacycline, imipenem-relabactam, and meropenem-vaborbactam, susceptibility data were available for fewer than 2% of isolates. Susceptibility comparisons should be considered with caution. Ceftazidime-avibactam had the highest susceptibility rates for Enterobacterales while cefiderocol had the highest susceptibility rates for Pseudomonas aeruginosa. New antibiotics have the potential to improve the management of Gram-negative infections, but their use may be hampered by the absence of susceptibility data.

High Prevalence of Carbapenem-Resistant Enterobacterales Colonization Among Intensive Care Unit Patients in a Tertiary Hospital, China

Intestinal colonization with carbapenem-resistant Enterobacterales (CRE) has been shown as a significant risk factor for subsequent CRE infections, especially in intensive care units (ICUs). The aim of this study was to determine the prevalence of intestinal CRE colonization among ICU patients in a Chinese tertiary hospital. Fecal sample screenings for CRE were performed on ICU patients weekly. Antibiotic-susceptibility profile of CRE strains was determined using the Vitek-2 analysis system and broth microdilution method. The carbapenemases of all isolates were determined by phenotypes and genotypes. Clonal relatedness was analyzed by pulsed-field gel electrophoresis (PFGE). Whole-genome sequencing was used to identify the multilocus sequence type (ST), plasmid replicons, and insertion sequences (ISs) of isolates. The overall colonization rate of CRE was 40.4% (82/203). A total of 84 CRE strains were detected, mostly with Klebsiella pneumoniae (92.9%). Antibiotic susceptibility testing profile revealed that 84 CRE strains were resistant to most antibiotics except for tigecycline and colistin. The carbapenemase-encoding genes including blaKPC-2, blaNDM-1, and blaIMP-4 were detected, and blaKPC-2 was the predominant genotype (90.8%). A total of 9 STs were identified among 84 CRE strains, and ST11 was the most common type (83.3%). A variety of mobile genetic elements, including plasmids and ISs, were detected via online tool prediction. PFGE analysis of the 78 K. pneumoniae strains showed 8 different pulsotypes, and pulsotype A was highly prevalent. This study found that the prevalence of CRE colonization was alarmingly high in the ICU, and that effective infection control measures are urgently needed to prevent the dissemination of CRE.

A photoactivatable and phenylboronic acid-functionalized nanoassembly for combating multidrug-resistant gram-negative bacteria and their biofilms

Background

Multidrug-resistant (MDR) gram-negative bacteria-related infectious diseases have caused an increase in the public health burden and mortality. Moreover, the formation of biofilms makes these bacteria difficult to control. Therefore, developing novel interventions to combat MDR gram-negative bacteria and their biofilms-related infections are urgently needed. The purpose of this study was to develop a multifunctional nanoassembly (IRNB) based on IR-780 and N, N'-di-sec-butyl-N, N'- dinitroso-1,4-phenylenediamine (BNN6) for synergistic effect on the infected wounds and subcutaneous abscesses caused by gram-negative bacteria.

Methods

The characterization and bacteria-targeting ability of IRNB were investigated. The bactericidal efficacy of IRNB against gram-negative bacteria and their biofilms was demonstrated by crystal violet staining assay, plate counting method and live/dead staining in vitro. The antibacterial efficiency of IRNB was examined on a subcutaneous abscess and cutaneous infected wound model in vivo. A cell counting kit-8 assay, Calcein/PI cytotoxicity assay, hemolysis assay and intravenous injection assay were performed to detect the biocompatibility of IRNB in vitro and in vivo.

Results

Herein, we successfully developed a multifunctional nanoassembly IRNB based on IR-780 and BNN6 for synergistic photothermal therapy (PTT), photodynamic therapy (PDT) and nitric oxide (NO) effect triggered by an 808 nm laser. This nanoassembly could accumulate specifically at the infected sites of MDR gram-negative bacteria and their biofilms via the covalent coupling effect. Upon irradiation with an 808 nm laser, IRNB was activated and produced both reactive oxygen species (ROS) and hyperthermia. The local hyperthermia could induce NO generation, which further reacted with ROS to generate ONOO-, leading to the enhancement of bactericidal efficacy. Furthermore, NO and ONOO- could disrupt the cell membrane, which converts bacteria to an extremely susceptible state and further enhances the photothermal effect. In this study, IRNB showed a superior photothermal-photodynamic-chemo (NO) synergistic therapeutic effect on the infected wounds and subcutaneous abscesses caused by gram-negative bacteria. This resulted in effective control of associated infections, relief of inflammation, promotion of re-epithelization and collagen deposition, and regulation of angiogenesis during wound healing. Moreover, IRNB exhibited excellent biocompatibility, both in vitro and in vivo.

Conclusions

The present research suggests that IRNB can be considered a promising alternative for treating infections caused by MDR gram-negative bacteria and their biofilms.

Association of SARS-CoV-2 status and antibiotic-resistant bacteria with inadequate empiric therapy in hospitalized patients: a US multicenter cohort evaluation (July 2019 - October 2021)

BACKGROUND

Antibiotic usage and antibiotic resistance (ABR) patterns changed during the COVID-19 pandemic. Inadequate empiric antibiotic therapy (IET) is a significant public health problem and contributes to ABR. We evaluated factors associated with IET before and during the COVID-19 pandemic to determine the impact of the pandemic on antibiotic management.

METHODS

This multicenter, retrospective cohort analysis included hospitalized US adults who had a positive bacterial culture (specified gram-positive or gram-negative bacteria) from July 2019 to October 2021 in the BD Insights Research Database. IET was defined as antibacterial therapy within 48 h that was not active against the bacteria. ABR results were based on susceptibility testing and reports from local facilities. Multivariate analysis was used to identify risk factors associated with IET in patients with any positive bacterial culture and ABR-positive cultures, including multidrug-resistant (MDR) bacteria.

RESULTS

Of 278,344 eligible patients in 269 hospitals, 56,733 (20.4%) received IET; rates were higher in patients with ABR-positive (n = 93,252) or MDR-positive (n = 39,000) cultures (34.9% and 45.0%, respectively). Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2)-positive patients had significantly higher rates of IET (25.9%) compared with SARS-CoV-2-negative (20.3%) or not tested (19.7%) patients overall and in the ABR and MDR subgroups. Patients with ABR- or MDR-positive cultures had more days of therapy and longer lengths of stay. In multivariate analyses, ABR, MDR, SARS-CoV-2-positive status, respiratory source, and prior admissions were identified as key IET risk factors.

CONCLUSIONS

IET remained a persistent problem during the COVID-19 pandemic and occurred at higher rates in patients with ABR/MDR bacteria or a co-SARS-CoV-2 infection.

Therapeutic drug monitoring of carbapenem antibiotics in critically ill patients: an overview of principles, recommended dosing regimens, and clinical outcomes

INTRODUCTION

The importance of antibiotic treatment for sepsis in critically ill septic patients is well established. Consistently achieving the dose of antibiotics required to optimally kill bacteria, minimize the development of resistance, and avoid toxicity is challenging. The increasing understanding of the pharmacokinetic and pharmacodynamic (PK/PD) characteristics of antibiotics, and the effects of critical illness on key PK/PD parameters, is gradually re-shaping how antibiotics are dosed in critically ill patients.

AREAS COVERED

The PK/PD characteristics of commonly used carbapenem antibiotics, the principles of the application of therapeutic drug monitoring (TDM), and current as well as future methods of utilizing TDM to optimally devise dosing regimens will be reviewed. The limitations and evidence-base supporting the use of carbapenem TDM to improve outcomes in critically ill patients will be examined.

EXPERT OPINION

It is important to understand the principles of TDM in order to correctly inform dosing regimens. Although the concept of TDM is attractive, and the ability to utilize PK software to optimize dosing in the near future is expected to rapidly increase clinicians' ability to meet pre-defined PK/PD targets more accurately, current evidence provides only limited support for the use of TDM to guide carbapenem dosing in critically ill patients.

Participant- and Disease-Related Factors as Independent Predictors of Treatment Outcomes in the RESTORE-IMI 2 Clinical Trial: A Multivariable Regression Analysis

Background

In the RESTORE-IMI 2 trial, imipenem/cilastatin/relebactam (IMI/REL) was noninferior to piperacillin/tazobactam in treating hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia. This post hoc analysis was conducted to determine independent predictors of efficacy outcomes in the RESTORE-IMI 2 trial, to assist in treatment decision making.

Methods

A stepwise multivariable regression analysis was conducted to identify variables that were independently associated with day 28 all-cause mortality (ACM), favorable clinical response at early follow-up (EFU), and favorable microbiologic response at end of treatment (EOT). The analysis accounted for the number of baseline infecting pathogens and in vitro susceptibility to randomized treatment.

Results

Vasopressor use, renal impairment, bacteremia at baseline, and Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II scores ≥15 were associated with a greater risk of day 28 ACM. A favorable clinical response at EFU was associated with normal renal function, an APACHE II score <15, no vasopressor use, and no bacteremia at baseline. At EOT, a favorable microbiologic response was associated with IMI/REL treatment, normal renal function, no vasopressor use, nonventilated pneumonia at baseline, intensive care unit admission at randomization, monomicrobial infections at baseline, and absence of Acinetobacter calcoaceticus-baumannii complex at baseline. These factors remained significant after accounting for polymicrobial infection and in vitro susceptibility to assigned treatment.

Conclusions

This analysis, which accounted for baseline pathogen susceptibility, validated well-recognized patient- and disease-related factors as independent predictors of clinical outcomes. These results lend further support to the noninferiority of IMI/REL to piperacillin/tazobactam and suggests that pathogen eradication may be more likely with IMI/REL.

Clinical Trials Registration

NCT02493764.

The Prevalence of Carbapenemase-Producing Microorganisms and Use of Novel Cephalosporins for the Treatment of Severe Infections Caused by Carbapenem-Resistant Gram-Negative Bacteria in a Pediatric Cardiac Intensive Care Unit

BACKGROUND

The spread of carbapenem-resistant organisms (CROs) is an increasingly serious threat globally, especially in vulnerable populations, such as intensive care unit (ICU) patients. Currently, the antibiotic options for CROs are very limited, particularly in pediatric settings. We describe a cohort of pediatric patients affected by CRO infections, highlighting the important changes in carbapenemase production in recent years and comparing the treatment with novel cephalosporins (N-CEFs) to Colistin-based regimens (COLI).

METHODS

All patients admitted to the cardiac ICU of the Bambino Gesù Children's Hospital in Rome during the 2016-2022 period with an invasive infection caused by a CRO were enrolled.

RESULTS

The data were collected from 42 patients. The most frequently detected pathogens were Pseudomonas aeruginosa (64%), Klebsiella pneumoniae (14%) and Enterobacter spp. (14%). Thirty-three percent of the isolated microorganisms were carbapenemase producers, with a majority of VIM (71%), followed by KPC (22%) and OXA-48 (7%). A total of 67% of patients in the N-CEF group and 29% of patients in the comparative group achieved clinical remission (p = 0.04).

CONCLUSION

The increase over the years of MBL-producing pathogens in our hospital is challenging in terms of therapeutic options. According to the present study, N-CEFs are a safe and effective option in pediatric patients affected by CRO infections.

Outcomes in participants with failure of initial antibacterial therapy for hospital-acquired/ventilator-associated bacterial pneumonia prior to enrollment in the randomized, controlled phase 3 ASPECT-NP trial of ceftolozane/tazobactam versus meropenem

BACKGROUND

Ceftolozane/tazobactam, a combination antibacterial agent comprising an anti-pseudomonal cephalosporin and β-lactamase inhibitor, is approved for the treatment of hospital-acquired/ventilator-associated bacterial pneumonia (HABP/VABP) in adults. Participants in the ASPECT-NP trial received ceftolozane/tazobactam (3 g [2 g ceftolozane/1 g tazobactam] every 8 h) or meropenem (1 g every 8 h). Participants failing prior antibacterial therapy for the current HABP/VABP episode at study entry had lower 28-day all-cause mortality (ACM) rates with ceftolozane/tazobactam versus meropenem treatment. Here, we report a post hoc analysis examining this result.

METHODS

The phase 3, randomized, controlled, double-blind, multicenter, noninferiority trial compared ceftolozane/tazobactam versus meropenem for treatment of adults with ventilated HABP/VABP; eligibility included those failing prior antibacterial therapy for the current HABP/VABP episode at study entry. The primary and key secondary endpoints were 28-day ACM and clinical response at test of cure (TOC), respectively. Participants who were failing prior therapy were a prospectively defined subgroup; however, subgroup analyses were not designed for noninferiority testing. The 95% CIs for treatment differences were calculated as unstratified Newcombe CIs. Post hoc analyses were performed using multivariable logistic regression analysis to determine the impact of baseline characteristics and treatment on clinical outcomes in the subgroup who were failing prior antibacterial therapy.

RESULTS

In the ASPECT-NP trial, 12.8% of participants (93/726; ceftolozane/tazobactam, n = 53; meropenem, n = 40) were failing prior antibacterial therapy at study entry. In this subgroup, 28-day ACM was higher in participants who received meropenem versus ceftolozane/tazobactam (18/40 [45.0%] vs 12/53 [22.6%]; percentage difference [95% CI]: 22.4% [3.1 to 40.1]). Rates of clinical response at TOC were 26/53 [49.1%] for ceftolozane/tazobactam versus 15/40 [37.5%] for meropenem (percentage difference [95% CI]: 11.6% [- 8.6 to 30.2]). Multivariable regression analysis determined concomitant vasopressor use and treatment with meropenem were significant factors associated with risk of 28-day ACM. Adjusting for vasopressor use, the risk of dying after treatment with ceftolozane/tazobactam was approximately one-fourth the risk of dying after treatment with meropenem.

CONCLUSIONS

This post hoc analysis further supports the previously demonstrated lower ACM rate for ceftolozane/tazobactam versus meropenem among participants who were failing prior therapy, despite the lack of significant differences in clinical cure rates.

CLINICALTRIALS

gov registration NCT02070757 . Registered February 25, 2014, clinicaltrials.gov/ct2/show/NCT02070757 .

Epidemiology and outcomes of culture-positive bloodstream pathogens prior to and during the SARS-CoV-2 pandemic: a multicenter evaluation

Background

Bloodstream infections (BSIs) are an important cause of morbidity and mortality in hospitalized patients. We evaluate incidence of community- and hospital-onset BSI rates and outcomes before and during the SARS-CoV-2 pandemic.

Methods

We conducted a retrospective cohort study evaluating patients who were hospitalized for ≥ 1 day with discharge or death between June 1, 2019, and September 4, 2021, across 271 US health care facilities. Community- and hospital-onset BSI and related outcomes before and during the SARS-CoV-2 pandemic, including intensive care admission rates, and overall and ICU-specific length of stay (LOS) was evaluated. Bivariate correlations were calculated between the pre-pandemic and pandemic periods overall and by SARS-CoV-2 testing status.

Results

Of 5,239,692 patient admissions, there were 20,113 community-onset BSIs before the pandemic (11.2/1000 admissions) and 39,740 (11.5/1000 admissions) during the pandemic (P ≤ 0.0062). Corresponding rates of hospital-onset BSI were 2,771 (1.6/1000 admissions) and 6,864 (2.0/1000 admissions; P < 0.0062). Compared to the pre-pandemic period, rates of community-onset BSI were higher in patients who tested negative for SARS-CoV-2 (15.8/1000 admissions), compared with 9.6/1000 BSI admissions among SARS-CoV-2-positive patients. Compared with patients in the pre-pandemic period, SARS-CoV-2-positive patients with community-onset BSI experienced greater ICU admission rates (36.6% vs 32.8%; P < 0.01), greater ventilator use (10.7% vs 4.7%; P < 0.001), and longer LOS (12.2 d vs 9.1 d; P < 0.001). Rates of hospital-onset BSI were higher in the pandemic vs the pre-pandemic period (2.0 vs 1.5/1000; P < 0.001), with rates as high a 7.3/1000 admissions among SARS-CoV-2-positive patients. Compared to the pre-pandemic period, SARS-CoV-2-positive patients with hospital-onset BSI had higher rates of ICU admission (72.9% vs 55.4%; P < 0.001), LOS (34.8 d vs 25.5 d; P < 0.001), and ventilator use (52.9% vs 21.5%; P < 0.001). Enterococcus species, Staphylococcus aureus, Klebsiella pneumoniae, and Candida albicans were more frequently detected in the pandemic period.

Conclusions and relevance

This nationally representative study found an increased risk of both community-onset and hospital-onset BSI during the SARS-CoV-2 pandemic period, with the largest increased risk in hospital-onset BSI among SARS-CoV-2-positive patients. SARS-CoV-2 positivity was associated with worse outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07810-8.

Hospital-onset bacteremia and fungemia: An evaluation of predictors and feasibility of benchmarking comparing two risk-adjusted models among 267 hospitals

Objectives:

To evaluate the prevalence of hospital-onset bacteremia and fungemia (HOB), identify hospital-level predictors, and to evaluate the feasibility of an HOB metric.

Methods:

We analyzed 9,202,650 admissions from 267 hospitals during 2015–2020. An HOB event was defined as the first positive blood-culture pathogen on day 3 of admission or later. We used the generalized linear model method via negative binomial regression to identify variables and risk markers for HOB. Standardized infection ratios (SIRs) were calculated based on 2 risk-adjusted models: a simple model using descriptive variables and a complex model using descriptive variables plus additional measures of blood-culture testing practices. Performance of each model was compared against the unadjusted rate of HOB.

Results:

Overall median rate of HOB per 100 admissions was 0.124 (interquartile range, 0.00–0.22). Facility-level predictors included bed size, sex, ICU admissions, community-onset (CO) blood culture testing intensity, and hospital-onset (HO) testing intensity, and prevalence (all P < .001). In the complex model, CO bacteremia prevalence, HO testing intensity, and HO testing prevalence were the predictors most associated with HOB. The complex model demonstrated better model performance; 55% of hospitals that ranked in the highest quartile based on their raw rate shifted to a lower quartile when the SIR from the complex model was applied.

Conclusions:

Hospital descriptors, aggregate patient characteristics, community bacteremia and/or fungemia burden, and clinical blood-culture testing practices influence rates of HOB. Benchmarking an HOB metric is feasible and should endeavor to include both facility and clinical variables.

In-vitro activity of plazomicin, meropenem-vaborbactam, and omadacycline against carbapenem-resistant Gram-negative isolates in Egypt

Anti-microbial resistance is an escalating worldwide threat. Thus, there is an utmost necessity for the introduction of novel anti-microbial agents. This research aimed to evaluate the in-vitro activity of plazomicin, meropenem-vaborbactam, and omadacycline against carbapenem-resistant Gram-negative isolates gathered from one Egyptian University group of Hospitals. 210 intensive care units (ICU) and 113 non-ICU samples were included. Resistance to carbapenems was reported in 37.5% and 21.05% of the isolated Gram-negative ICU and non-ICU organisms respectively (P < 0.001). Via disc diffusion, the sensitivity rates for carbapenem-resistant non-ICU and ICU strains were 68.8% & 64.4% for plazomicin, 68.8% & 48.9% for meropenem-vaborbactam, and 56.25% & 44.5% for omadacycline, respectively. Regarding MIC₅₀/_90, it was 1/16 μg/mL for plazomicin and 4/32 μg/mL for both meropenem-vaborbactam and omadacycline separately. In conclusion, plazomicin displayed potent activity against carbapenem-resistant strains. Moreover, meropenem-vaborbactam and omadacycline demonstrated satisfactory results.

A Multicenter Comparison of Carbapenem-Nonsusceptible Enterobacterales and Pseudomonas aeruginosa Rates in the US (2016 to 2020): Facility-Reported Rates versus Rates Based on Updated Clinical Laboratory and Standards Institute Breakpoints

Adoption of revised antimicrobial susceptibility breakpoints is often slow, potentially leading to underreporting of antimicrobial resistance. We compared facility-reported rates of carbapenem nonsusceptibility (NS; intermediate or resistant) with NS rates based on current Clinical and Laboratory Standards Institute (CLSI) breakpoints for Enterobacterales or Pseudomonas aeruginosa isolates in ambulatory and inpatient adults in the BD Insights Research Database (US) from 2016 to 2020. Overall, 77.4% (937,926/1,211,845) and 90.6% (2,157,785/2,381,824) of nonduplicate Enterobacterales isolates with facility-reported susceptibility results had MIC data for ertapenem (ETP) and imipenem/meropenem/doripenem (IPM/MEM/DOR), respectively; 86.9% (255,844/294,426) of P. aeruginosa isolates had MIC data for IPM/MEM/DOR. Facility-reported susceptibility and susceptibility based on CLSI criteria resulted in comparable carbapenem susceptibility rates (99.3% versus 99.1% for ETP-susceptible Enterobacterales, 98.9% versus 98.4% for IPM/MEM/DOR-susceptible Enterobacterales, and 84.9% versus 83.3% for IPM/MEM/DOR-susceptible P. aeruginosa). However, compared with CLSI criteria, facilities underreported Enterobacterales- and IPM/MEM/DOR-NS isolates by 18.8% and 26.5%, respectively, and P. aeruginosa IPM/MEM/DOR-NS isolates by 9.8%. Underreporting was observed for both intermediate and resistant isolates. Our data suggest that delayed adoption of revised breakpoints has a small but potentially important impact on reported rates of antimicrobial resistance. Facilities should be aware of local epidemiology, evaluate potential underreporting of resistance, and assess the related clinical impact. IMPORTANCE Clinicians often base antimicrobial therapeutic decisions on laboratory determinations of pathogen susceptibility to an antibiotic based on MIC breakpoints. MIC breakpoints evolve over time based on new information; between 2010 and 2012 the CLSI lowered carbapenem breakpoints for Enterobacterales and Pseudomonas aeruginosa, and these were subsequently adopted by the US Food and Drug Administration. Carbapenems are important therapeutic options for these difficult-to-treat pathogens, so understanding resistance rates is critically important. However, laboratories can be slow to adopt updated breakpoints. We used MIC data to evaluate whether reports received by hospitals for carbapenem susceptibility were consistent with updated CLSI breakpoints. Although overall susceptibility rates were similar between hospital reports and susceptibility based on updated CLSI criteria, the percentages of carbapenem-resistant isolates were significantly underreported by hospital reports. Delayed adoption of MIC breakpoints may impact epidemiological understanding of resistance and contribute to the spread of resistant pathogens.

Bloodstream Infections Caused by Carbapenem-Resistant Pathogens in Intensive Care Units: Risk Factors Analysis and Proposal of a Prognostic Score

Considering the growing prevalence of carbapenem-resistant Gram-negative bacteria (CR-GNB) bloodstream infection (BSI) in intensive care units (ICUs), the identification of specific risk factors and the development of a predictive model allowing for the early identification of patients at risk for CR-Klebsiella pneumoniae, Acinetobacter baumannii or Pseudomonas aeruginosa are essential. In this retrospective case–control study including all consecutive patients showing an episode of BSI in the ICUs of a university hospital in Italy in the period January–December 2016, patients with blood culture positive for CR-GNB pathogens and for any other bacteria were compared. A total of 106 patients and 158 episodes of BSI were identified. CR-GNBs induced BSI in 49 patients (46%) and 58 episodes (37%). Prognosis score and disease severity at admission, parenteral nutrition, cardiovascular surgery prior to admission to ICU, the presence of sepsis and septic shock, ventilation-associated pneumonia and colonization of the urinary or intestinal tract were statistically significant in the univariate analysis. The duration of ventilation and mortality at 28 days were significantly higher among CR-GNB cases. The prognostic model based on age, presence of sepsis, previous cardiovascular surgery, SAPS II, rectal colonization and invasive respiratory infection from the same pathogen showed a C-index of 89.6%. The identified risk factors are in line with the international literature. The proposal prognostic model seems easy to use and shows excellent performance but requires further studies to be validated.

Epidemiology of Antimicrobial Resistance Among Blood and Respiratory Specimens in the United States Using Genotypic Analysis from a Cloud-Based Population Surveillance Network

Background

Antimicrobial resistance (AMR) surveillance is critical in informing strategies for infection control in slowing the spread of resistant organisms and for antimicrobial stewardship in the care of patients. However, significant challenges exist in timely and comprehensive AMR surveillance.

Methods

Using BioFire Pneumonia and Blood Culture 2 Panels data from BioFire Syndromic Trends (Trend), a cloud-based population surveillance network, we described the detection rate of AMR among a US cohort. Data were included from 2019 to 2021 for Gram-positive and -negative organisms and their related AMR genomic-resistant determinants as well as for detections of Candida auris. Regional and between panel AMR detection rate differences were compared. In addition, AMR codetections and detection rate per organism were evaluated for Gram-negative organisms.

Results

A total of 26 912 tests were performed, primarily in the Midwest. Overall, AMR detection rate was highest in the South and more common for respiratory specimens than blood. methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus detection rates were 34.9% and 15.9%, respectively, whereas AMR for Gram-negative organisms was lower with 7.0% CTX-M and 2.9% carbapenemases. In addition, 10 mcr-1 and 4 C auris detections were observed. For Gram-negative organisms, Klebsiella pneumoniae and Escherichia coli were most likely to be detected with an AMR gene, and of Gram-negative organisms, K pneumoniae was most often associated with 2 or more AMR genes.

Conclusions

Our study provides important in-depth evaluation of the epidemiology of AMR among respiratory and blood specimens for Gram-positive and -negative organism in the United States. The Trend surveillance network allows for near real-time surveillance of AMR.

The Economic Impact of Carbapenem Resistant-Non Lactose Fermenter and Enterobacteriaceae Infections on Hospital Costs in Dr. Soetomo General Academic Hospital Surabaya, Indonesia

Background: Carbapenem resistant-non lactose fermenter (CR-NLF) and Carbapenem resistant-Enterobacteriaceae (CR-E) bacterial infections are likely to be a global threat to people’s health. However, studies on the economic impacts according to the hospital setting are very scarce. The study aimed to explore the impact of CR-NLF (Acinetobacter baumannii = CRAB) & Pseudomonas aeruginosa = CRPA) and CR-E (Escherichia coli = CREC) & Klebsiella pneumoniae = CRKP) infections on hospital costs from a payer perspective among patients admitted to Dr.Soetomo Hospital, Surabaya, Indonesia. Methods: In the retrospective case-control study, medical records of all included patients hospitalized during 2018−2021 were reviewed for CRAB, CRPA, CREC, CRKP, and carbapenem sensitive (CSAB, CSPA, CSEC, CSKP) were collected. We retrieved the data of age, gender, clinical specimen, dates of admission, and discharge status. The outcomes of interest were hospital length of stay and hospitalization cost. Results: The cost for CR-NLFs infections was higher than carbapenem sensitive, $3026.24 versus $1299.28 (p < 0.05). There was no significant difference between CR-E against carbapenem sensitive. It showed that the highest impact of the cost was CRAB, followed by CRPA, CRKP, and CREC. The bed, antibiotics, pharmacy, and diagnostic costs of CR-NLFIs were significantly higher than CR-E. Conclusion: This study showed that the hospital cost and expenditure of CR-NLFs per patient were higher than CS. The hospital cost per patient for CR-NLF was higher than CR-E.

Comparative Genomics Revealed Fluoroquinolone Resistance Determinants and OmpF Deletion in Carbapenem-Resistant Escherichia coli

Escherichia coli (E. coli) is a major causative organism of complicated urinary tract infections, bloodstream infections, and pneumonia. With the widespread use of antimicrobial agents, the prevalence of carbapenem resistance in E. coli has been increasing with limited therapeutic options. Fluoroquinolone remains a choice in carbapenem-resistant E. coli (CREc) that were once susceptible to the drug. Despite robust studies on the fluoroquinolone-resistant mechanisms of E. coli, few studies focused specifically on the group of CREc. In this study, we used comparative genomics to identify the fluoroquinolone-resistant mechanisms of CREc and detected gyrA D87N mutation in all the fluoroquinolone-resistant and CREc. Moreover, to investigate the mechanism underlying non-carbapenemase-producing carbapenem-resistant E. coli, we targeted the complete genome sequences for in-depth analysis and found a deletion in OmpF (DEL264-269) that might contribute to carbapenem resistance, which has not been reported before. Further studies focusing on the impact of these mutations on the expression levels are warranted. We further investigate the MLST, serotype, fimH type, phylogroup, and clinical characteristics of the CREc. Combination analysis of clinical and genomic characteristics suggests the polyclonal and highly diverse nature of the CREc in Taiwan. This study provides an insight into the molecular epidemiology of CREc in Taiwan.

The Ins and Outs of Susceptibility Testing for New β-Lactam/β-Lactamase Inhibitor Combinations for Gram-Negative Organisms

Ceftazidime-avibactam, meropenem-vaborbactam, and imipenem-relebactam are among the newest β-lactam/β-lactamase inhibitors (BL/BLIs) introduced to the North American antibiotic market. All have broad Gram-negative activity, including against certain carbapenemases. Despite this, susceptibility testing is warranted due to variable activity against certain β-lactamases (e.g., oxacillinases) and the presence of acquired resistance mechanisms in some isolates. Here, we discuss what we know about these new antimicrobial agents and how to navigate implementation of susceptibility testing and reporting of these agents in clinical laboratories.

A multicenter analysis of trends in resistance in urinary Enterobacterales isolates from ambulatory patients in the United States: 2011-2020

BACKGROUND

Urinary tract infections (UTIs), which are usually caused by bacteria in the Enterobacterales family, are a common reason for outpatient visits. Appropriate empiric therapy for UTIs requires an understanding of antibiotic resistance in the community. In this nationwide study, we examined trends in antibiotic resistance in urinary Enterobacterales isolates from ambulatory patients in the United States (US).

METHODS

We analyzed the antimicrobial susceptibility profiles (extended-spectrum beta-lactamase [ESBL]-producing phenotype and not susceptible [NS] to beta-lactams, trimethoprim/sulfamethoxazole [TMP/SMX], fluoroquinolones [FQ], or nitrofurantoin [NFT]) of 30-day non-duplicate Enterobacterales isolates from urine cultures tested at ambulatory centers in the BD Insights Research Database (2011-2020). The outcome of interest was the percentage of resistant isolates by pathogen and year. Multi-variable generalized estimating equation models were used to assess trends in resistance over time and by additional covariates.

RESULTS

A total of 338 US facilities provided data for > 2.2 million urinary Enterobacterales isolates during the 10-year study. Almost three-quarters (72.8%) of Enterobacterales isolates were Escherichia coli. Overall unadjusted resistance rates in Enterobacterales isolates were 57.5%, 23.1%, 20.6%, and 20.2% for beta-lactams, TMP/SMX, FQ, and NFT, respectively, and 6.9% had an ESBL-producing phenotype. Resistance to two or more antibiotic classes occurred in 16.4% of isolates and 5.5% were resistant to three or more classes. Among isolates with an ESBL-producing phenotype, 70.1%, 59.9%, and 33.5% were NS to FQ, TMP/SMX, and NFT, respectively. In multivariable models, ESBL-producing and NFT NS Enterobacterales isolates increased significantly (both P < 0.001), while other categories of resistance decreased. High rates (≥ 50%) of beta-lactam and NFT resistance were observed in Klebsiella isolates and in non-E. coli, non-Klebsiella Enterobacterales isolates.

CONCLUSIONS

Antimicrobial resistance was common in urinary Enterobacterales isolates. Isolates with an ESBL-producing phenotype increased by about 30% between 2011 and 2020, and significant increases were also observed in NFT NS Enterobacterales isolates. Resistance rates for all four antibiotic classes were higher than thresholds recommended for use as empiric therapy. Non-E. coli Enterobacterales isolates showed high levels of resistance to commonly used empiric antibiotics, including NFT. These data may help inform empiric therapy choices for outpatients with UTIs.

Antibiotic Resistance Patterns and Association with the Influenza Season in the United States: A Multicenter Evaluation Reveals Surprising Associations Between Influenza Season and Resistance in Gram-negative Pathogens

Background

Viral infections are often treated with empiric antibiotics due to suspected bacterial coinfections, leading to antibiotic overuse. We aimed to describe antibiotic resistance (ABR) trends and their association with the influenza season in ambulatory and inpatient settings in the United States.

Methods

We used the BD Insights Research Database to evaluate antibiotic susceptibility profiles in 30-day nonduplicate bacterial isolates collected from patients >17 years old at 257 US healthcare institutions from 2011 to 2019. We investigated ABR in Gram-positive (Staphylococcus aureus and Streptococcus pneumoniae) and Gram-negative (Enterobacterales [ENT], Pseudomonas aeruginosa [PSA], and Acinetobacter baumannii spp [ACB]) bacteria expressed as the proportion of isolates not susceptible ([NS], intermediate or resistant) and resistance per 100 admissions (inpatients only). Antibiotics included carbapenems (Carb), fluoroquinolones (FQ), macrolides, penicillin, extended-spectrum cephalosporins (ESC), and methicillin. Generalized estimating equations models were used to evaluate monthly trends in ABR outcomes and associations with community influenza rates.

Results

We identified 8 250 860 nonduplicate pathogens, including 154 841 Gram-negative Carb-NS, 1 502 796 Gram-negative FQ-NS, 498 012 methicillin-resistant S aureus (MRSA), and 44 131 NS S pneumoniae. All S pneumoniae rates per 100 admissions (macrolide-, penicillin-, and ESC-NS) were associated with influenza rates. Respiratory, but not nonrespiratory, MRSA was also associated with influenza. For Gram-negative pathogens, influenza rates were associated with the percentage of FQ-NS ENT, FQ-NS PSA, and Carb-NS ACB.

Conclusions

Our study showed expected increases in rates of ABR Gram-positive and identified small but surprising increases in ABR Gram-negative pathogens associated with influenza activity. These insights may help inform antimicrobial stewardship initiatives.

Pseudomonas aeruginosa Pneumonia: Evolution of Antimicrobial Resistance and Implications for Therapy

Pseudomonas aeruginosa (PA), a non-lactose-fermenting gram-negative bacillus, is a common cause of nosocomial infections in critically ill or debilitated patients, particularly ventilator-associated pneumonia (VAP), and infections of urinary tract, intra-abdominal, wounds, skin/soft tissue, and bloodstream. PA rarely affects healthy individuals, but may cause serious infections in patients with chronic structural lung disease, comorbidities, advanced age, impaired immune defenses, or with medical devices (e.g., urinary or intravascular catheters, foreign bodies). Treatment of pseudomonal infections is difficult, as PA is intrinsically resistant to multiple antimicrobials, and may acquire new resistance determinants even while on antimicrobial therapy. Mortality associated with pseudomonal VAP or bacteremias is high (> 35%) and optimal therapy is controversial. Over the past three decades, antimicrobial resistance (AMR) among PA has escalated globally, via dissemination of several international multidrug resistant "epidemic" clones. We discuss the importance of PA as a cause of pneumonia including health care-associated pneumonia, hospital-acquired pneumonia, VAP, the emergence of AMR to this pathogen, and approaches to therapy (both empirical and definitive).

Burden of illness in carbapenem-resistant Acinetobacter baumannii infections in US hospitals between 2014 and 2019

Background

Carbapenem-resistant (CR) Acinetobacter baumannii is a concerning pathogen in the USA and worldwide.

Methods

To assess the comparative burden of CR vs carbapenem-susceptible (CS) A. baumannii, this retrospective cohort study analyzed data from adult patients in 250 US hospitals from the Premier HealthCare Database (2014–2019). The outcomes analyzed included hospital length of stay (LOS), intensive care unit (ICU) utilization, discharge status, in-hospital mortality, readmission rates and hospital charges. Logistic regression was used for univariate and multivariable assessment of the independent relationship between relevant covariates, with a focus on CR status, and in-hospital mortality.

Results

2047 Patients with CR and 3476 patients with CS A. baumannii infections were included. CR A. baumannii was more commonly isolated in respiratory tract infections (CR 40.7% and CS 27.0%, P < 0.01), whereas CS A. baumannii was more frequently associated with bloodstream infections (CS 16.7% and CR 8.6%, P < 0.01). Patients with CR A. baumannii infections had higher in-hospital (CR 16.4% vs CS 10.0%; P < 0.01) and 30-day (CR 32.2% vs CS 21.6%; P < 0.01) mortality compared to those with CS infections. After adjusting for age, sex, admission source, infection site, comorbidities, and treatment with in vitro active antibiotics within 72 h, carbapenem resistance was independently associated with increased mortality (adjusted odds ratio 1.42 [95% confidence interval 1.15; 1.75], P < 0.01). CR infections were also associated with increases in hospital length of stay (CR 11 days vs CS 9 days; P < 0.01), rate of intensive care unit utilization (CR 62.3% vs CS 45.1%; P < 0.01), rate of readmission with A. baumannii infections (CR 17.8% vs CS 4.0%; P < 0.01) and hospital charges.

Conclusions

These data suggest that the burden of illness is significantly greater for patients with CR A. baumannii infections and are at higher risk of mortality compared with CS infections in US hospitals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-07024-4.

In Vitro Activity of Ceftolozane/Tazobactam against Gram-Negative Isolates collected from ICU Patients with Lower Respiratory Tract Infections in Seven Asian Countries - SMART 2017-2019

OBJECTIVES

Antimicrobial resistance is one of the top 10 global public health threats. Especially high rates of resistance have been reported for isolates from ICU patients, requiring expanded treatment options in this setting. We evaluated the activity of ceftolozane/tazobactam and comparators against gram-negative isolates collected from patients with lower respiratory tract infections (LRTI) in ICUs in seven Asian countries.

METHODS

In 2017-2019, up to 100 consecutive aerobic gram-negative LRTI isolates were collected per year at each of 37 hospitals. MICs were determined using the Clinical and Laboratory Standards Institute reference broth microdilution method.

RESULTS

Overall, ceftolozane/tazobactam was active against 72% of 1408 Enterobacterales and 86% of 761 P. aeruginosa isolates. Susceptibility to the non-carbapenem β-lactam comparators, including piperacillin/tazobactam, was 52-67% among Enterobacterales isolates, and the activity of all β-lactam comparators, including meropenem, was 57-70% among P. aeruginosa. Ceftolozane/tazobactam maintained activity against 61% of meropenem-nonsusceptible and 64% of piperacillin/tazobactam-nonsusceptible P. aeruginosa isolates. At the country-level, ceftolozane/tazobactam activity ranged from >90% against Enterobacterales isolates from Hong Kong and South Korea to <64% in Thailand and Vietnam, and from >90% against P. aeruginosa from South Korea, Malaysia, Philippines, and Taiwan to <75% in Thailand and Vietnam. Correspondingly, the proportions of carbapenemase-positive isolates among Enterobacterales and P. aeruginosa isolates were highest in Thailand and Vietnam.

CONCLUSIONS

Ceftolozane/tazobactam provides a potential treatment option for ICU patients in Asia, which is especially important considering the reduced activity of commonly used β-lactams against the studied ICU isolates. Knowledge of local resistance patterns should inform empiric therapy decision-making.

Changing Epidemiology and Decreased Mortality Associated With Carbapenem-resistant Gram-negative Bacteria, 2000-2017

BACKGROUND

Carbapenem-resistant gram-negative bacteria (CRGNB) continue to present a global healthcare crisis. We aimed to identify emerging trends of CRGNB over nearly 2 decades and describe the impact of CRGNB on patient outcomes.

METHODS

Patients from whom CRGNB were isolated between 2000 and 2017 were included in the study. Carbapenem resistance was defined by the most recent breakpoints and applied across the study period. Patient demographics, clinical characteristics, and outcomes were retrieved from the electronic health record.

RESULTS

A total of 94 888 isolates from 64 422 patients were identified; 9882 (10%) isolates from 4038 patients were carbapenem-resistant. Pseudomonas aeruginosa was the most common CRGNB each year. The second most common CRGNB emerged in waves over time. Carbapenem daily defined doses increased in parallel with CRGNB rates (R2 = 0.8131). The overall 30-day mortality rate was 19%, which decreased from 24% in 2000 to 17% in 2017 (P = .003; R2 = .4330). Among patients with CRGNB bloodstream infections (n = 319), overall 30- and 90-day mortality rates were 27% and 38%, respectively. Charlson score (adjusted odds ratio [aOR], 1.11 per point), intensive care unit residence (aOR, 7.32), and severe liver disease (aOR, 4.8.4) were independent predictors of 30-day mortality, while receipt of transplantation was associated with lower rates of death (aOR, 0.39). Among patients admitted between 2011 and 2017 (n = 2230), 17% died during hospitalization, 32% were transferred to long-term care facilities, and 38% were discharged home.

CONCLUSIONS

CRGNB emerged in waves over time, causing high rates of mortality. Despite increasing rates of CRGNB, overall patient outcomes have improved, suggesting that recognition and novel therapeutics have made a major impact.

Real-world experience of how chlorhexidine bathing affects the acquisition and incidence of vancomycin-resistant enterococci (VRE) in a medical intensive care unit with VRE endemicity: a prospective interrupted time-series study

BACKGROUND

Critically ill patients in intensive care units (ICUs) often acquire opportunistic infections or are colonized by vancomycin-resistant enterococci (VRE), which limits therapeutic options and results in high case-fatality rates. In clinical practice, the beneficial effects of universal chlorhexidine gluconate (CHG) bathing on the control of VRE remain unclear. This study aimed to investigate whether 2% CHG daily bathing reduced the acquisition of VRE in the setting of a medical ICU (MICU) with VRE endemicity.

METHODS

This quasi-experimental intervention study was conducted in a 23-bed MICU of a tertiary care hospital in Korea from September 2016 to December 2017. In a prospective, interrupted time-series analysis (ITS) with a 6-month CHG bathing intervention, we compared the acquisition and incidence of VRE and the incidence of methicillin-resistant Staphylococcus aureus (MRSA) and carbapenem-resistant Acinetobacter baumannii (CRAB) between the pre-intervention and intervention periods. The primary and secondary outcomes were a change in the acquisition of VRE and incidence of VRE, MRSA, or CRAB between the two periods, respectively.

RESULTS

All the adult patients admitted to the MICU were enrolled in the pre-intervention (n = 259) and intervention (n = 242). The overall CHG daily bathing compliance rate was 72.5%. In the ITS, there was a significant intervention effect with a 58% decrease in VRE acquisition (95% CI 7.1-82.1%, p = 0.038) following the intervention. However, there was no significant intervention effects on the incidence trend of VRE, MRSA, and CRAB determined by clinical culture between the pre-intervention and intervention periods.

CONCLUSION

In this real-world study, we concluded that daily bathing with CHG may be an effective measure to reduce VRE cross-transmission among patients in MICU with a high VRE endemicity.

Carbapenem-resistant Enterobacterales colonization and subsequent infection in a neonatal intensive care unit in Shanghai, China

Background

Colonization has been reported to play an important role in carbapenem-resistant Enterobacterales (CRE) infection; however, the extent to which carriers develop clinical CRE infection and related risk factors in neonatal intensive care unit (NICU) patients is unclear.

Aim

To investigate the frequency of CRE colonization and its contribution to infections in NICU patients.

Methods

CRE colonization screening and CRE infection surveillance were performed in the NICU in 2017 and 2018.

Findings

Among 1230 unique NICU patients who were screened for CRE colonization, 144 patients tested positive (11.7%, 144/1230), with 9.2% (110/1197) in the intestinal tract, which was higher than that in the upper respiratory tract (6.6%, 62/945) (P=0.026). Gestational age, low birth weight and prolonged hospitalization were risk factors for CRE colonization (all P<0.001). Diversilab homology monitoring found an overall 17.4% (25/144) risk of infection among patients colonized with CRE. For carbapenem-resistant Klebsiella pneumoniae (CR-KP) and carbapenem-resistant Escherichia coli (CR-ECO), the risks were 19.1% (21/110) and 13.8% (4/29), respectively. The independent risk factors for CR-KP clinical infection among CR-KP carriers were receiving mechanical ventilation (odds ratio (OR), 10.177; 95% confidence interval (CI), 2.667–38.830; P=0.013), a high level of neonatal nutritional risk assessment (OR, 0.251; 95% CI, 0.072–0.881; P=0.031) and a high neonatal acute physiology II (SNAP-II) score (OR, 0.256; 95% CI, 0.882–1.034; P=0.025).

Conclusions

The colonization of CRE may increase the incidence of corresponding CRE infection in NICU patients. Receiving mechanical ventilation, malnutrition and critical conditions with high SNAP-II scores were independent risk factors for subsequent CR-KP clinical infection.

The impact of infections on reimbursement in 92 US hospitals, 2015-2018

BACKGROUND

The diagnosis-related group (DRG) is a payment system introduced to standardize healthcare costs. However, reimbursement for treatment of infections does not always cover costs.

METHODS

We used 2015-2018 data from 92 US hospitals in the Becton Dickinson Insights Research Database to compare the financial burden of hospital admissions within non-infection DRGs for patients with a bacterial infection (INF+) versus those without an infection (INF-). Included patients were adults with a hospital length of stay (LOS) ≥3 days and evidence of infection. Multi-variable adjusted analyses via generalized linear mixed models were used to evaluate the impact of an infection on outcomes.

RESULTS

We analyzed data from 133,423 INF+ admissions and 170,531 INF- admissions. Infections were associated with an approximately two-fold increase in model-estimated LOS (9.2 vs 4.8 d; P < .001) and intensive care unit LOS (5.1 vs 2.8 d; P < .001). The average additional hospital cost for INF+ versus INF- admissions was $10,326 per admission (P < .001) and the average loss after reimbursement was $1,067 (P = .006). Only private insurance payers had a positive margin.

CONCLUSIONS

Current reimbursement options for infections result in significant hospital financial burden. Reimbursement models should be reconsidered to enable adoption of costlier diagnostics and antimicrobials.

Susceptibility to Imipenem/Relebactam of Pseudomonas aeruginosa and Acinetobacter baumannii Isolates from Chinese Intra-Abdominal, Respiratory and Urinary Tract Infections: SMART 2015 to 2018

Purpose

In recent years, less options are available for treating carbapenem-resistant Acinetobacter baumannii and carbapenem-resistant Pseudomonas aeruginosa. The present study investigates the susceptibility rates to imipenem/relebactam for the treatment of intra-abdominal infections (IAIs), respiratory tract infections (RTIs) and urinary tract infections (UTIs) caused by A. baumannii and P. aeruginosa in China.

Patients and Methods

A total of 1886 P. aeruginosa and 1889 A. baumannii isolates were collected in 21 centers (7 regions) as a part of the global SMART surveillance program between 2015 and 2018. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute (CLSI) recommendations using the broth microdilution methodology at Peking Union Medical College Hospital.

Results

For P. aeruginosa, overall susceptibility rates to imipenem/relebactam were 84.2% at a CLSI breakpoint of ≤2 mg/L compared to 55.7% for imipenem. Susceptibility rates of imipenem-non-susceptible P. aeruginosa to imipenem/relebactam were 64.4% and for multidrug-resistance (MDR) P. aeruginosa susceptibility rates were increased from 25.2% for imipenem to 65.8% for imipenem/relebactam. The susceptibilities of imipenem-non-susceptible and MDR P. aeruginosa strains were similarly restored by imipenem/relebactam in non-ICU and ICU wards. The rate of imipenem-non-susceptibilities A. baumannii isolates was 79.0%, whereas the MDR rate was 81.9%. Relebactam did not change the susceptibilities of imipenem-non susceptible or MDR A. baumannii isolates.

Conclusion

Imipenem/relebactam provides a therapy option to treat infections caused by MDR or imipenem-non-susceptible P. aeruginosa but not A. baumannii infections in China.

Molecular Characterization Identifies Upstream Presence of ISAba1 to OXA Carbapenemase Genes in Carbapenem-Resistant Acinetobacter baumannii Isolated from a Tertiary Care Hospital in Western Maharashtra

Background  Evaluating the expression pattern of oxacillinases (OXA) carbapenemases is essential to understand the prevalence and spread of carbapenem resistance Acinetobacter baumannii .

Objectives  The aim of the study is to evaluate the presence of OXA carbapenemase genes and IS Aba1 upstream to these genes in carbapenem-resistant A. baumannii clinical isolates.

Materials and Methods   A. baumannii isolated from clinical samples were phenotypically identified and antibiotics sensitivity was performed. Multiplex polymerase chain reaction (PCR) was used to detect OXA51-like gene, OXA carbapenemases genes (OXA-23-like, OXA-24-like, and OXA-58-like), and IS Aba1 in carbapenem-resistant isolates.

Results  Out of 55 Acinetobacter isolates, 54 were confirmed as A. baumannii by PCR. Bla_OXA-23 -like gene was observed in 51 isolates of A. baumannii and none of the isolates showed the presence of bla_OXA-24 -like and bla_OXA-58 -like genes. Presence of IS Aba1 upstream to OXA-23-like gene, OXA-51-like gene, and both OXA-51-like/OXA-23-like genes was observed in 51, 7, and 4 A. baumannii isolates, respectively.

Conclusion  The genetic pattern of carbapenem-resistant A. baumannii isolated in this study was unique, which should be factored for clinical protocols to manage infections caused by emerging resistant strains of A. baumannii .

In Vitro Antibacterial Activity of Cefiderocol against Multidrug-Resistant Acinetobacter baumannii

Cefiderocol (CFDC), a novel siderophore cephalosporin, demonstrates strong activity against multidrug-resistant (MDR) Acinetobacter baumannii. Limited studies have evaluated CFDC alone and in combination with other Gram-negative antibiotics against MDR A. baumannii isolates. Susceptibility testing revealed lower CFDC MIC values (87% of MICs ≤ 4mg/liter) than the comparator Gram-negative agents. Six isolates, with elevated CFDC MICs (16 to 32 mg/liter) were selected for further experiments. Time-kill analyses presented with synergistic activity and beta-lactamase inhibitors increased CFDC susceptibility in each of the isolates.

Non-fermentative gram-negative bloodstream infection in northern Italy: a multicenter cohort study

Background

The management of non-fermentative gram-negative bloodstream infection (NFGN-BSI) offers numerous challenges. In this study the aim is to analyse a large cohort of patients with NFGN-BSI recruited in the northern Italy to describe epidemiology, etiological and susceptibility pattern, therapeutic management and outcome.

Methods

Multicentre retrospective cohort study of patients hospitalised at three large teaching hospitals in northern Italy in a fourth year period.

Results

355 BSI episodes were analyzed, due to P. aeruginosa (72.7%), A. baumannii (16.6%), and Stenotrophomonas maltophilia (10.7%). Overall, 21.4% of isolates were defined as DTR, highest rate among A. baumannii (64.4%). All-cause 30-day mortality rate was 17.5%. Rates of XDR or DTR A. baumannii isolation were significantly higher in non-surviving patients. Independent risk factors for 30-day mortality were: age (HR 1.03, 95%CI 1.00–1.04, p = 0.003), septic shock (HR 2.84, 95%CI 1.67–4.82, p < 0.001) and BSI due to Acinetobacter baumannii (HR 2.23, 95%CI 1.27–3.94, p = 0.005).

Conclusion

The overall prevalence of DTR was high in the NFGN BSI cohort analyzied, mainly among Acinetobacter baumannii episodes (64.4%). Acinetobacter baumannii is showed to be an independent predictor of mortality. These evidences marked the urgent need of new therapeutic options against this pathogen.

Trial registration number: 79/2017/O/OssN. Approved: March14th, 2017.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06496-8.

Ceftolozane/Tazobactam and Imipenem/Relebactam Cross-Susceptibility Among Clinical Isolates of Pseudomonas aeruginosa From Patients With Respiratory Tract Infections in ICU and Non-ICU Wards-SMART United States 2017-2019

BACKGROUND

Carbapenem-nonsusceptible and multidrug-resistant (MDR) P. aeruginosa, which are more common in patients with lower respiratory tract infections (LRTIs) and in patients in intensive care units (ICUs), pose difficult treatment challenges and may require new therapeutic options. Two β-lactam/β-lactamase inhibitor combinations, ceftolozane/tazobactam (C/T) and imipenem/relebactam (IMI/REL), are approved for treatment of hospital-acquired/ventilator-associated bacterial pneumonia.

METHODS

The Clinical and Laboratory Standards Institute-defined broth microdilution methodology was used to determine minimum inhibitory concentrations (MICs) against P. aeruginosa isolates collected from patients with LRTIs in ICUs (n = 720) and non-ICU wards (n = 914) at 26 US hospitals in 2017-2019 as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART) surveillance program.

RESULTS

Susceptibility to commonly used β-lactams including carbapenems was 5-9 percentage points lower and MDR rates 7 percentage points higher among isolates from patients in ICUs than those in non-ICU wards (P < .05). C/T and IMI/REL maintained activity against 94.0% and 90.8% of ICU isolates, respectively, while susceptibility to all comparators except amikacin (96.0%) was 63%-76%. C/T and IMI/REL inhibited 83.1% and 68.1% of meropenem-nonsusceptible (n = 207) and 71.4% and 65.7% of MDR ICU isolates (n = 140), respectively. Among all ICU isolates, only 2.5% were nonsusceptible to both C/T and IMI/REL, while 6.7% were susceptible to C/T but not to IMI/REL and 3.5% were susceptible to IMI/REL but not to C/T.

CONCLUSIONS

These data suggest that susceptibility to both C/T and IMI/REL should be considered for testing at hospitals, as both agents could provide important new options for treating patients with LRTIs, especially in ICUs where collected isolates show substantially reduced susceptibility to commonly used β-lactams.

Dual-Function Potentiation by PEG-BPEI Restores Activity of Carbapenems and Penicillins against Carbapenem-Resistant Enterobacteriaceae

The rise of life-threatening carbapenem-resistant Enterobacteriaceae (CRE) infections has become a critical medical threat. Some of the most dangerous CRE bacteria can produce enzymes that degrade a wide range of antibiotics, including carbapenems and β-lactams. Infections by CRE have a high mortality rate, and survivors can have severe morbidity from treatment with toxic last-resort antibiotics. CRE have mobile genetic elements that transfer resistance genes to other species. These bacteria also circulate throughout the healthcare system. The mobility and spread of CRE need to be curtailed, but these goals are impeded by having few agents that target a limited range of pathogenic CRE species. Against CRE possessing the metallo-β-lactamase NDM-1, Klebsiella pneumoniae ATCC BAA-2146 and Escherichia coli ATCC BAA-2452, the potentiation of meropenem and imipenem is possible with low-molecular weight branched polyethylenimine (600 Da BPEI) and its poly(ethylene glycol) (PEG)ylated derivative (PEG-BPEI) that has a low in vivo toxicity. The mechanism of action is elucidated with fluorescence assays of drug influx and isothermal calorimetry data showing the chelation of essential Zn2+ ions. These results suggested that 600 Da BPEI and PEG-BPEI may also improve the uptake of antibiotics and β-lactamase inhibitors. Indeed, the CRE E. coli strain is rendered susceptible to the combination of piperacillin and tazobactam. These results expand the possible utility of 600 Da BPEI potentiators, where previously we have demonstrated the ability to improve antibiotic efficacy against antibiotic resistant clinical isolates of Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis.

Effect of Inadequate Empiric Antibacterial Therapy on Hospital Outcomes in SARS-CoV-2-Positive and -Negative US Patients With a Positive Bacterial Culture: A Multicenter Evaluation From March to November 2020

Background

Increased utilization of antimicrobial therapy has been observed during the coronavirus disease 2019 pandemic. We evaluated hospital outcomes based on the adequacy of antibacterial therapy for bacterial pathogens in US patients.

Methods

This multicenter retrospective study included patients with ≥24 hours of inpatient admission, ≥24 hours of antibiotic therapy, and discharge/death from March to November 2020 at 201 US hospitals in the BD Insights Research Database. Included patients had a test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and a positive bacterial culture (gram-positive or gram-negative). We used generalized linear mixed models to evaluate the impact of inadequate empiric therapy (IET), defined as therapy not active against the identified bacteria or no antimicrobial therapy in the 48 hours following culture, on in-hospital mortality and hospital and intensive care unit length of stay (LOS).

Results

Of 438 888 SARS-CoV-2-tested patients, 39 203 (8.9%) had positive bacterial cultures. Among patients with positive cultures, 9.4% were SARS-CoV-2 positive, 74.4% had a gram-negative pathogen, 25.6% had a gram-positive pathogen, and 44.1% received IET for the bacterial infection. The odds of mortality were 21% higher for IET (odds ratio [OR], 1.21; 95% CI, 1.10–1.33; P < .001) compared with adequate empiric therapy. IET was also associated with increased hospital LOS (LOS, 16.1 days; 95% CI, 15.5–16.7 days; vs LOS, 14.5 days; 95% CI, 13.9–15.1 days; P < .001). Both mortality and hospital LOS findings remained consistent for SARS-CoV-2-positive and -negative patients.

Conclusions

Bacterial pathogens continue to play an important role in hospital outcomes during the pandemic. Adequate and timely therapeutic management may help ensure better outcomes.

Antimicrobial stewardship and antibiograms: importance of moving beyond traditional antibiograms

The rapid evolution of resistance, particularly among Gram-negative bacteria, requires appropriate identification of patients at risk followed by administration of appropriate empiric antibiotic therapy. A primary tenet of antimicrobial stewardship programs (ASPs) is the establishment of empiric antibiotic recommendations for commonly encountered infections. An important tool in providing empiric antibiotic therapy recommendations is the use of an antibiogram. While the majority of institutions use a traditional antibiogram, ASPs have an opportunity to enhance antibiogram data. The authors provide the rationale for why ASPs should implement alternative antibiograms, and the importance of incorporating an antibiogram into clinical decision support systems with the goal of providing effective empiric antibiotic therapy.

Molecular detection of carbapenem resistance genes in rectal swabs from patients in Gulf Cooperation Council hospitals

BACKGROUND

Gram-negative organisms harbouring carbapenem resistance genes (CRGs) are spreading globally, including in Gulf Cooperation Council (GCC) countries. However, relatively few data are available about carriage of CRGs in hospitalized patients in this region.

AIM

To determine prevalence of CRG carriage and risk factors for colonization among patients in GCC hospitals.

METHODS

Rectal swabs were obtained from ∼50 intensive care unit (ICU) patients from each of 11 hospitals in five GCC countries between March and November 2019. The swabs were tested for the presence of bla_KPC, bla_NDM, bla_VIM, bla_IMP, and bla_OXA-48 CRG using a commercial polymerase chain reaction test. Data on risk factors for colonization were collected and analysed.

FINDINGS

Of 529 specimens screened, 138 (26.1%) were positive for one or more CRGs. The positivity rates among the hospitals ranged from 8.0% to 67.3%; ∼20% of the positive specimens harboured ≥2 CRGs. The most common CRG detected was bla_OXA-48, which was present in 82 specimens (15.5%). Additional CRGs included bla_NDM, bla_VIM, bla_KPC, and bla_IMP either alone or in combination. Overall, 31.1% of patients on antibiotics on admission to the ICU were positive for CRGs compared to 16.5% not on antibiotic therapy (P < 0.001). CRG detection was also more common among patients aged >65 years (P = 0.027) and increased with hospital length of stay (P = 0.025).

CONCLUSION

The rate of CRGs detected in hospitalized patients in GCC countries varied considerably. Prior antibiotic exposure, increasing age, and prolonged length of stay were associated with CRG detection.

Mortality Among US Patients Hospitalized With SARS-CoV-2 Infection in 2020

IMPORTANCE

Mortality is an important measure of the severity of a pandemic. This study aimed to understand how mortality by age of hospitalized patients who were tested for SARS-CoV-2 has changed over time.

OBJECTIVE

To evaluate trends in in-hospital mortality among patients who tested positive for SARS-CoV-2.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cohort study included patients who were hospitalized for at least 1 day at 1 of 209 US acute care hospitals of variable size, in urban and rural areas, between March 1 and November 21, 2020. Eligible patients had a SARS-CoV-2 polymerase chain reaction (PCR) or antigen test within 7 days of admission or during hospitalization, and a record of discharge or in-hospital death.

EXPOSURE

SARS-CoV-2 positivity.

MAIN OUTCOMES AND MEASURES

SARS-CoV-2 infection was defined as a positive SARS-CoV-2 PCR or antigen test within 7 days before admission or during hospitalization. Mortality was extracted from electronically available data.

RESULTS

Among 503 409 admitted patients, 42 604 (8.5%) had SARS-CoV-2-positive tests. Of those with SARS-CoV-2-positive tests, 21 592 (50.7%) were male patients. Hospital admissions among patients with SARS-CoV-2-positive tests were highest in the group aged 65 years or older (19 929 [46.8%]), followed by those aged 50 to 64 years (11 602 [27.2%]) and 18 to 49 years (10 619 [24.9%]). Hospital admissions among patients 18 to 49 years of age increased from 1099 of 5319 (20.7%) in April to 1266 of 4184 (30.3%) in June and 2156 of 7280 (29.6%) in July, briefly exceeding those in the group 50 to 64 years of age (June: 1194 of 4184 [28.5%]; 2039 of 7280 [28.0%]). Patients with SARS-CoV-2-positive tests had higher in-hospital mortality than patients with SARS-CoV-2-negative tests (4705 [11.0%] vs 11 707 of 460 805 [2.5%]; P < .001). In-hospital mortality rates increased with increasing age for both patients with SARS-CoV-2-negative tests and SARS-CoV-2-positive tests. In patients with SARS-CoV-2-negative tests, mortality increased from 45 of 11 255 (0.4%) in those younger than 18 years to 4812 of 107 394 (4.5%) in those older than 75 years. In patients with SARS-CoV-2-positive tests, mortality increased from 1 of 454 (0.2%) of those younger than 18 years to 2149 of 10 287 (20.9%) in those older than 75 years. In-hospital mortality rates among patients with SARS-CoV-2-negative tests were similar for male and female patients (6273 of 209 086 [3.0%] vs 5538 of 251 719 [2.2%]) but higher mortality was observed among male patients with SARS-CoV-2-positive tests (2700 of 21 592 [12.5%]) compared with female patients with SARS-CoV-2-positive tests (2016 of 21 012 [9.60%]). Overall, in-hospital mortality increased from March to April (63 of 597 [10.6%] to 1047 of 5319 [19.7%]), then decreased significantly to November (499 of 5350 [9.3%]; P = .04), with significant decreases in the oldest age groups (50-64 years: 197 of 1542 [12.8%] to 73 of 1341 [5.4%]; P = .02; 65-75 years: 269 of 1182 [22.8%] to 137 of 1332 [10.3%]; P = .006; >75 years: 535 of 1479 [36.2%] to 262 of 1505 [17.4%]; P = .03).

CONCLUSIONS AND RELEVANCE

This nationally representative study supported the findings of smaller, regional studies and found that in-hospital mortality declined across all age groups during the period evaluated. Reductions were unlikely because of a higher proportion of younger patients with lower in-hospital mortality in the later period.

Distribution and Antimicrobial Susceptibility of Gram-Positive and Gram-Negative Pathogens Isolated from Patients Hospitalized in a Tertiary Teaching Hospital in Southwestern China

Background: Bacteria are the most common causes of clinical infectious diseases. The distribution and antimicrobial resistance (AMR) rates of bacteria provide important guidelines for clinical antibacterial treatment; however, the information in this region is still missing. Objectives: This study aimed to evaluate the changes in the distribution and AMR rates of clinical isolates from inpatients. Methods: We conducted a retrospective cross-sectional analysis of the distribution and antimicrobial susceptibility of all non-duplicate Gram-negative bacterial (GNB) and Gram-positive bacterial (GPB) isolates collected from January 1, 2013, to December 31, 2018, in our hospital. Results: In total, 56,535 and 3,518 non-repetitive isolates were detected in the whole hospital and intensive care units (ICUs), respectively. The isolates included GPB (26.3% and 18.4%, respectively) and GNB (73.7% and 81.6%, respectively). The five dominant bacteria were the same in the whole hospital and ICUs, but Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii percentages were different. The detection rates of all isolates and five dominant bacteria were significantly different between the ICUs and the whole hospital (P < 0.05). The detection rate of extended-spectrum β-lactamase (ESBL)-E. coli (54.1%) was significantly higher than that of K. pneumoniae (26.1%). The detection rates of carbapenem-resistant (CR) and extensively drug-resistant (XDR)-A. baumannii were the highest in both the ICUs (87.1% and 21.8%, respectively) and the whole hospital (65.5% and 12.9%, respectively). The methicillin-resistant S. aureus (MRSA) detection rate was high (26.5%) but showed a significant decreasing trend (P < 0.05). The detection rates of ESBL and XDR-E. coli, CRAB, and XDR-S. aureus were significantly different between the ICUs and the whole hospital (P < 0.05). Gram-negative bacteria were highly susceptible to amikacin (> 90%) and tigecycline (> 98%). Staphylococcus aureus showed 100% susceptibility to vancomycin and linezolid. Acinetobacter baumannii had the highest resistance to imipenem (62.8%) and meropenem (64.0%). Except for A. baumannii and E. coli (P < 0.05), the AMR levels and the trends of the other isolates were similar between the ICUs and the whole hospital (P > 0.05). Conclusions: Currently, the appropriate antimicrobial agents in our hospital include amikacin and tigecycline for the treatment of GNB infections and vancomycin and linezolid for the treatment of GPB infections. Moreover, it is still necessary to monitor AMR in the ICUs and the whole hospital simultaneously.

A multicenter analysis of the clinical microbiology and antimicrobial usage in hospitalized patients in the US with or without COVID-19

BACKGROUND

Past respiratory viral epidemics suggest that bacterial infections impact clinical outcomes. There is minimal information on potential co-pathogens in patients with coronavirus disease-2019 (COVID-19) in the US. We analyzed pathogens, antimicrobial use, and healthcare utilization in hospitalized US patients with and without severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2).

METHODS

This multicenter retrospective study included patients with > 1 day of inpatient admission and discharge/death between March 1 and May 31, 2020 at 241 US acute care hospitals in the BD Insights Research Database. We assessed microbiological testing data, antimicrobial utilization in admitted patients with ≥24 h of antimicrobial therapy, and length of stay (LOS).

RESULTS

A total of 141,621 patients were tested for SARS-CoV-2 (17,003 [12.0%] positive) and 449,339 patients were not tested. Most (> 90%) patients tested for SARS-CoV-2 had additional microbiologic testing performed compared with 41.9% of SARS-CoV-2-untested patients. Non-SARS-CoV-2 pathogen rates were 20.9% for SARS-CoV-2-positive patients compared with 21.3 and 27.9% for SARS-CoV-2-negative and -untested patients, respectively. Gram-negative bacteria were the most common pathogens (45.5, 44.1, and 43.5% for SARS-CoV-2-positive, -negative, and -untested patients). SARS-CoV-2-positive patients had higher rates of hospital-onset (versus admission-onset) non-SARS-CoV-2 pathogens compared with SARS-CoV-2-negative or -untested patients (42.4, 22.2, and 19.5%, respectively), more antimicrobial usage (68.0, 45.2, and 25.1% of patients), and longer hospital LOS (mean [standard deviation (SD)] of 8.6 [11.4], 5.1 [8.9], and 4.2 [8.0] days) and intensive care unit (ICU) LOS (mean [SD] of 7.8 [8.5], 3.6 [6.2], and 3.6 [5.9] days). For all groups, the presence of a non-SARS-CoV-2 pathogen was associated with increased hospital LOS (mean [SD] days for patients with versus without a non-SARS-CoV-2 pathogen: 13.7 [15.7] vs 7.3 [9.6] days for SARS-CoV-2-positive patients, 8.2 [11.5] vs 4.3 [7.9] days for SARS-CoV-2-negative patients, and 7.1 [11.0] vs 3.9 [7.4] days for SARS-CoV-2-untested patients).

CONCLUSIONS

Despite similar rates of non-SARS-CoV-2 pathogens in SARS-CoV-2-positive, -negative, and -untested patients, SARS-CoV-2 was associated with higher rates of hospital-onset infections, greater antimicrobial usage, and extended hospital and ICU LOS. This finding highlights the heavy burden of the COVID-19 pandemic on healthcare systems and suggests possible opportunities for diagnostic and antimicrobial stewardship.

A Multicenter Evaluation of the US Prevalence and Regional Variation in Macrolide-Resistant S. pneumoniae in Ambulatory and Hospitalized Adult Patients in the United States

Macrolide resistance was found in 39.5% of 3626 nonduplicate Streptococcus pneumoniae isolates from adult ambulatory and inpatient settings at 329 US hospitals (2018–2019). Macrolide resistance was significantly higher for respiratory vs blood isolates and ambulatory vs inpatient settings. Despite geographic variation, S. pneumoniae macrolide resistance was >25% in most regions.

Imipenem/Cilastatin/Relebactam: A Review in Gram-Negative Bacterial Infections

Imipenem/cilastatin/relebactam (Recarbrio™) is an intravenously administered combination of the carbapenem imipenem, the renal dehydropeptidase-I inhibitor cilastatin, and the novel β-lactamase inhibitor relebactam. Relebactam is a potent inhibitor of class A and class C β-lactamases, conferring imipenem activity against many imipenem-nonsusceptible strains. Imipenem/cilastatin/relebactam is approved in the USA and EU for the treatment of hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP) in adults and other gram-negative infections, including complicated urinary tract infections (cUTIs) [including pyelonephritis] and complicated intra-abdominal infections (cIAIs), in adults with limited or no alternative treatment options. In pivotal phase II and III trials, imipenem/cilastatin/relebactam was noninferior to piperacillin/tazobactam in patients with HABP/VABP and to imipenem/cilastatin in patients with cUTIs and cIAIs. It was also effective in imipenem-nonsusceptible infections. Imipenem/cilastatin/relebactam was generally well tolerated, with a safety profile consistent with that of imipenem/cilastatin. Available evidence indicates that imipenem/cilastatin/relebactam is an effective and generally well tolerated option for gram-negative infections in adults, including critically ill and/or high-risk patients, and a potential therapy for infections caused by carbapenem-resistant pathogens.

Cefiderocol: A Novel Siderophore Cephalosporin against Multidrug-Resistant Gram-Negative Pathogens

Cefiderocol (CFDC), (formerly S-649266), is a novel injectable siderophore cephalosporin developed by Shionogi & Co., Ltd., with potent in vitro activity against Gram-negative pathogens including multidrug-resistant (MDR) Enterobacteriaceae and non-fermenting organisms, such as Pseudomonas aeruginosa, Acinetobacter baumannii, Burkholderia cepacia, and Stenotrophomonas maltophilia. Characterized by its siderophore catechol-moiety, CFDC uses a "trojan-horse approach" to navigate through the bacterial periplasmic space, thus evading various beta-lactam degrading enzymes and other mechanisms of resistance present in Gram-negative bacteria. More specifically in carbapenem-resistant Enterobacteriaceae, CFDC has been shown to have activity against extended spectrum beta-lactamases (ESBLs), such as CTX-type, SHV-type, and TEM-type, as well as the Ambler classes of beta-lactamases, including class A (KPC), class B (NDM, IMP, and VIM), class C (AmpC), and class D (OXA, OXA-24, OXA-48, and OXA-48-like). In addition to the strong activity that CFDC has been shown to have against MDR P. aeruginosa, it has also displayed activity against the OXA-23, OXA-24, and OXA-51, beta-lactamases commonly found in MDR A. baumannii. Cefiderocol was recently approved by the US Food and Drug Administration (FDA) for use in complicated urinary tract infections (cUTI), including pyelonephritis, for use in patients 18 years or older with limited or no alternative options for treatment, and is currently being evaluated in a phase III trial for use in nosocomial pneumonia caused by Gram-negative pathogens. The unique features and enhanced activity of CFDC suggest that it is likely to serve as a viable therapeutic option in the treatment of MDR Gram-negative infections. The purpose of this review is to provide an overview of previously published literature explaining CFDC's pharmacology, pharmacokinetic / pharmacodynamic (PK / PD) properties, microbiologic activity, resistance mechanisms, safety parameters, dosing and administration, clinical data, and potential place in therapy.

Antimicrobial Activity of Colistin Against Contemporary (2015 – 2017) P. aeruginosa and A. baumannii Isolates From a Chinese Surveillance Program

Objective

To investigate the incidence and susceptibilities of non-fermenting bacteria isolates from Chinese respiratory (RTI), intra-abdominal (IAI) and urinary tract (UTI) infections to antimicrobial agents between 2015 and 2017.

Methods

In total, 3,246 non-fermentative bacteria were collected from 21 hospitals and 9 hospital departments across 7 regions of China. A central testing laboratory was employed to determine antimicrobial susceptibilities using appropriate standards of interpretation.

Results

The majority of the isolates were Acinetobacter baumannii (n = 1,360, 41.9%) and Pseudomonas aeruginosa (n = 1,341, 41.3%). Overall multidrug resistance (MDR) and carbapenem resistance (CR) rates of Acinetobacter baumannii were 80.1 and 78.7% with MDR and CR rates in RTIs, IAIs, and UTIs of 82.0 and 81.0%, 82.6 and 81.0% as well as 53.1 and 46.9%. Overall MDR and CR rates of Pseudomonas aeruginosa isolates were 36.2 and 38.9% with 41.8 and 44.3%, 29.3 and 36.1% as well as 24.2 and 20.2% MDR and CR rates in RTIs, IAIs, and UTIs. Overall susceptibility rates to imipenem, meropenem, amikacin, ciprofloxacin, cefepime and piperacillin-tazobactam were 21.1, 21.3, 33.0, 18.4, 19.2, and 19.6% for Acinetobacter baumannii and 56.5, 58.5, 88.4, 63.1, 63.1, and 55.63% for Pseudomonas aeruginosa isolates, whereas for colistin they were 95.7 and 94.6%, respectively. In all departments and regions of China, susceptibility rates of Pseudomonas aeruginosa and Acinetobacter baumannii isolates to colistin were constantly above 80%.

Conclusion

Due to the high MDR and CR rates for Pseudomonas aeruginosa and Acinetobacter baumannii, isolates obtained from RTIs, IAIs, and UTIs only maintained high susceptibility rates to colistin between 2015 and 2017.

Epidemiology and Diagnostics of Carbapenem Resistance in Gram-negative Bacteria

Carbapenem resistance in gram-negative bacteria has caused a global epidemic that continues to grow. Although carbapenemase-producing Enterobacteriaceae have received the most attention because resistance was first reported in these pathogens in the early 1990s, there is increased awareness of the impact of carbapenem-resistant nonfermenting gram-negative bacteria, such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia. Moreover, evaluating the problem of carbapenem resistance requires the consideration of both carbapenemase-producing bacteria as well as bacteria with other carbapenem resistance mechanisms. Advances in rapid diagnostic tests to improve the detection of carbapenem resistance and the use of large, population-based datasets to capture a greater proportion of carbapenem-resistant organisms can help us gain a better understanding of this urgent threat and enable physicians to select the most appropriate antibiotics.

Epidemiology and regional variation of nonsusceptible and multidrug-resistant Pseudomonas aeruginosa isolates from intensive versus non-intensive care units across multiple centers in the United States

Nonsusceptible (NS) and multidrug-resistant (MDR) Pseudomonas aeruginosa (PsA) infections are associated with considerable mortality. This retrospective study assessed NS PsA and MDR PsA prevalence in US intensive care unit (ICU) and non-ICU settings. We evaluated nonduplicate PsA isolates collected in 2017. Data were classified by hospital admission setting. PsA isolates were evaluated for NS to each of 4 drug classes and MDR. Significantly higher rates of NS PsA and MDR PsA were found in ICU versus non-ICU settings (P < .001), except for respiratory isolates, which had high rates regardless of setting; rates also correlated with source, hospital size, urban/rural status, and geographic region. NS PsA isolates for each antibacterial category (except fluoroquinolones) and MDR PsA were significantly more likely to be classified as hospital-onset than admission-onset (P < .001). These data are consistent with previous reports and emphasize the importance of testing for resistant infection upon admission and when treating hospital-acquired infections.

In Vitro Activity of Cefiderocol, a Novel Siderophore Cephalosporin, against Gram-Negative Bacilli Isolated from Patients in Canadian Intensive Care Units

The in vitro activity of cefiderocol was evaluated against Gram-negative bacilli isolated from patients in Canadian intensive care units from 2015 to 2017 using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method and interpretive criteria. All 800 isolates of Gram-negative bacilli tested were susceptible to cefiderocol (MIC ≤4 μg/ml), including isolates of ESBL-producing (n=40), AmpC-producing (n=6), and carbapenem-nonsusceptible (n=21) Enterobacterales, carbapenem-nonsusceptible (n=54) and multidrug-resistant (n=29) Pseudomonas aeruginosa, Stenotrophomonas maltophilia (n=66), and Acinetobacter baumannii (n=11).

The incidence and prevalence of hospital-acquired (carbapenem-resistant) Acinetobacter baumannii in Europe, Eastern Mediterranean and Africa: a systematic review and meta-analysis

Due to therapeutic challenges, hospital-acquired infections (HAIs) caused by Acinetobacter baumannii (HA-AB), particularly carbapenem-resistant strains (HA-CRAB) pose a serious health threat to patients worldwide. This systematic review sought to summarize recent data on the incidence and prevalence of HA-AB and HA-CRAB infections in the WHO-defined regions of Europe (EUR), Eastern Mediterranean (EMR) and Africa (AFR). A comprehensive literature search was performed using MEDLINE, EMBASE and GMI databases (01/2014-02/2019). Random-effects meta-analyses were performed to determine the pooled incidence of HA-AB and HA-CRAB infections as well as the proportions of A. baumannii among all HAIs. 24 studies from 3,340 records were included in this review (EUR: 16, EMR: 6, AFR: 2). The pooled estimates of incidence and incidence density of HA-AB infection in intensive care units (ICUs) were 56.5 (95% CI 33.9-92.8) cases per 1,000 patients and 4.4 (95% CI 2.9-6.6) cases per 1,000 patient days, respectively. Five studies conducted at a hospital-wide level or in specialized clinical departments/wards (ICU + non-ICU patients) showed HA-AB incidences between 0.85 and 5.6 cases per 1,000 patients. For carbapenem-resistant A. baumannii infections in ICUs, the pooled incidence and incidence density were 41.7 (95% CI 21.6-78.7) cases per 1,000 patients and 2.1 (95% CI 1.2-3.7) cases per 1,000 patient days, respectively. In ICUs, A. baumannii and carbapenem-resistant A. baumannii strains accounted for 20.9% (95% CI 16.5-26.2%) and 13.6% (95% CI 9.7-18.7%) of all HAIs, respectively. Our study highlights the persistent clinical significance of hospital-acquired A. baumannii infections in the studied WHO regions, particularly in ICUs.

Multidrug-Resistant Bacterial Infections in U.S. Hospitalized Patients, 2012-2017

BACKGROUND

Multidrug-resistant (MDR) bacteria that are commonly associated with health care cause a substantial health burden. Updated national estimates for this group of pathogens are needed to inform public health action.

METHODS

Using data from patients hospitalized in a cohort of 890 U.S. hospitals during the period 2012-2017, we generated national case counts for both hospital-onset and community-onset infections caused by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococcus (VRE), extended-spectrum cephalosporin resistance in Enterobacteriaceae suggestive of extended-spectrum beta-lactamase (ESBL) production, carbapenem-resistant Enterobacteriaceae, carbapenem-resistant acinetobacter species, and MDR Pseudomonas aeruginosa.

RESULTS

The hospital cohort in the study accounted for 41.6 million hospitalizations (>20% of U.S. hospitalizations annually). The overall rate of clinical cultures was 292 cultures per 1000 patient-days and was stable throughout the time period. In 2017, these pathogens caused an estimated 622,390 infections (95% confidence interval [CI], 579,125 to 665,655) among hospitalized patients. Of these infections, 517,818 (83%) had their onset in the community, and 104,572 (17%) had their onset in the hospital. MRSA and ESBL infections accounted for the majority of the infections (52% and 32%, respectively). Between 2012 and 2017, the incidence decreased for MRSA infection (from 114.18 to 93.68 cases per 10,000 hospitalizations), VRE infection (from 24.15 to 15.76 per 10,000), carbapenem-resistant acinetobacter species infection (from 3.33 to 2.47 per 10,000), and MDR P. aeruginosa infection (from 13.10 to 9.43 per 10,000), with decreases ranging from -20.5% to -39.2%. The incidence of carbapenem-resistant Enterobacteriaceae infection did not change significantly (from 3.36 to 3.79 cases per 10,000 hospitalizations). The incidence of ESBL infection increased by 53.3% (from 37.55 to 57.12 cases per 10,000 hospitalizations), a change driven by an increase in community-onset cases.

CONCLUSIONS

Health care-associated antimicrobial resistance places a substantial burden on patients in the United States. Further work is needed to identify improved interventions for both the inpatient and outpatient settings. (Funded by the Centers for Disease Control and Prevention.).