Recommendations and guidelines for the treatment of infections due to multidrug resistant organisms

Geographic differences in susceptibility profiles of potential non-class B carbapenemase-producing Enterobacterales isolates against ceftazidime-avibactam, meropenem-vaborbactam, colistin, amikacin, gentamicin, and tigecycline: Data from the Antimicrobial Testing Leadership and Surveillance, 2018-2022

To evaluate the susceptibility profiles of regional meropenem-resistant (MEM-R) potential non-class B carbapenemase-producing Enterobacterales (CPE) isolates (without confirmation by phenotypic tests) against important antibiotics, we extracted data from the 2018-2022 Antimicrobial Testing Leadership and Surveillance. This data included susceptibility information of MEM-R potential non-class B CPE isolates against indicated antibiotics - amikacin [AMK], gentamicin [GM], ceftazidime-avibactam [CZA], colistin [CST], meropenem-vaborbactam [MVB], and tigecycline [TGC] - from sepsis patients hospitalized in ICUs across six major regions. Carbapenemase-encoding genes of the tested CPE isolates, determined by multiplex PCR and Sanger sequencing, were also analyzed. Susceptibility breakpoints recommended by CLSI 2024 and US FDA criteria (for TGC only) against Enterobacterales were employed. A total of 1,500 potential non-class B CPE isolates (89% of which were Klebsiella pneumoniae) were tested globally. Resistance rates to AMK and GM against the evaluated isolates were statistically higher in Africa/the Middle East, Europe, and India compared to other regions. A similar pattern was observed in the susceptibility of these potential CPE isolates to CZA and MVB. High CST resistance rates were noted in Asia, Latin America, and Europe (29%-35%). Furthermore, the proportions of potential CPE isolates carrying genes encoding blaOXA variants were notably higher among the tested CPE isolates in India, Europe, and Africa/the Middle East regions (99.2%, 53.3%, and 96.7%, respectively) compared to other regions. Trends in resistance to important antibiotics among potential non-class B CPE isolates warrant close monitoring.

Optimizing Treatment Strategies for Carbapenem-Resistant Acinetobacter Baumannii-Associated Pneumonia: A Multicenter Study in Chinese Hospitals

Purpose

To evaluate the clinical outcomes and safety of tigecycline (TGC) plus cefoperazone/sulbactam (CPS) or TGC monotherapy in patients with hospital-acquired pneumonia (HAP) caused by Carbapenem-Resistant Acinetobacter baumannii (CRAB).

Methods

This was a retrospective analysis of multicenter data from 62 Chinese hospitals with CRAB HAP. Risk factors for receiving TGC with CPS therapy and predictors of mortality were assessed using multivariate logistic and Cox regression analyses, respectively. Propensity score matching (PSM) evaluated the efficacy and safety of antimicrobial regimens.

Results

A total of the 180 patients were included, with 95 receiving TGC monotherapy and 85 receiving combination therapy. Multivariate logistic regression analysis revealed that older age (P = 0.011), and intensive care unit (ICU) admission (P = 0.007) were significant risk factors for combination therapy. Multivariate Cox regression demonstrated that combination therapy was associated with a significantly higher risk of 90-day mortality (P = 0.031). Patients in the standard-dose TGC (SDT) plus CPS subgroup had significantly higher rates of SOFA scores ≥ 7 (P = 0.009) and MV used (P = 0.028), as well as higher 30-/90-day mortality compared to high-dose TGC (HDT) plus CPS group. TGC plus CPS significantly reduced CRP levels (P = 0.009), while the variations in ALT, TBIL, Cr, Hb, and PLT levels did not differ between different antimicrobial regimens after PSM.

Conclusion

HDT and CPS combination therapy was more effective in patients with advanced age and more severe condition. Safety profiles of different antimicrobial regimens were similar with liver, kidneys, and coagulation functions.

Reduced mortality with antimicrobial stewardship guided by BioFire FilmArray Blood Culture Identification 2 panel in critically ill patients with bloodstream infection: A retrospective propensity score-matched study

OBJECTIVES

To investigate whether using the BioFire® FilmArray® Blood Culture Identification 2 panel (BCID2) leads to timely antimicrobial therapy and improves patient outcomes in critically ill patients with bloodstream infections (BSIs).

METHODS

This retrospective observational study included patients with BSIs admitted to the intensive care unit from July 1, 2021, to August 31, 2023. Patients were divided into groups receiving appropriate or inappropriate antimicrobial therapy. Those receiving inappropriate therapy underwent adjustments using standard-of-care (SOC) testing or BCID2. Propensity score matching (PSM) was performed on the original cohort (Model 1) and a time-window bias-adjusted cohort (Model 2). Clinical impact of BCID2-guided antimicrobial adjustment was analysed in both models.

RESULTS

A total of 181 patients received inappropriate antimicrobial therapy, with 33 undergoing BCID2 testing and 148 undergoing SOC testing. Following PSM and time-window bias adjustment, 66 patients were analysed in Model 1 and 46 patients in Model 2. BCID2 significantly reduced the median time to appropriate antimicrobial therapy (40.8 vs. 74.0 h in Model 1; 42.8 vs. 68.9 h in Model 2) and the day-28 mortality rate (27.8% vs. 77.1%, P < 0.001 in Model 1; 23.5% vs. 58.6%, P = 0.021 in Model 2). In multivariate regression analysis, BCID2-guided antimicrobial adjustment was an independent prognostic factor for day-28 mortality (adjusted odds ratio [aOR] 0.07 in Model 1 and aOR 0.12 in Model 2).

CONCLUSION

BCID2-guided antimicrobial stewardship was associated with a shorter time to appropriate antimicrobial therapy and reduced day-28 mortality in critically ill patients with BSIs receiving inappropriate antimicrobial therapy.

Polymyxin combined with Ocimum gratissimum essential oil: one alternative strategy for combating polymyxin-resistant Klebsiella pneumoniae

Introduction. Multidrug-resistant infections present a critical public health due to scarce treatment options and high mortality. Ocimum gratissimum L. essential oil (O.geo) is a natural resource rich in eugenol known for its antimicrobial activity.Hypothesis/Gap Statement. O.geo may exert effective antimicrobial activity against polymyxin-resistant Klebsiella pneumoniae and, when combined with Polymyxin B (PMB), may exhibit a synergistic effect, enhancing treatment efficacy and reducing antimicrobial resistance.Aim. This study aims to investigate the antimicrobial activity of O.geo against polymyxin-resistant K. pneumoniae using in vitro tests and an in vivo Caenorhabditis elegans model.Methodology. The O.geo was obtained by hydrodistillation followed by gas chromatography. The MIC and antibiofilm activity were determined using broth microdilution. Checkerboard and time-kill assays evaluated the combination of O.geo and polymyxin B (PMB), whereas a protein leakage assay verified its action.Results. Eugenol (39.67%) was a major constituent identified. The MIC of the O.geo alone ranged from 128 to 512 µg ml-1. The fractional inhibitory concentration index (0.28) and time-kill assay showed a synergism. In addition, O.geo and PMB inhibited biofilm formation and increased protein leakage in the plasma membrane. The treatment was tested in vivo using a Caenorhabditis elegans model, and significantly increased survival without toxicity was observed.Conclusion. O.geo could be used as a potential therapeutic alternative to combat infections caused by multidrug-resistant bacteria, especially in combination with PMB.

Guidelines for Antibacterial Treatment of Carbapenem-Resistant Enterobacterales Infections

This guideline aims to promote the prudent use of antibacterial agents for managing carbapenem-resistant Enterobacterales (CRE) infections in clinical practice in Korea. The general section encompasses recommendations for the management of common CRE infections and diagnostics, whereas each specific section is structured with key questions that are focused on antibacterial agents and disease-specific approaches. This guideline covers both currently available and upcoming antibacterial agents in Korea.

Characteristics and Prevalence of Vancomycin-variable Enterococcus faecium bacteremia in southern Taiwan

BACKGROUND

Vancomycin-variable enterococci (VVE) are vanA-carrying Enterococcus faecium that are phenotypically susceptible to vancomycin and can only be detected using molecular methods, leading to the possibility of treatment failure and posing threats to infection control. This study aimed to determine the prevalence of VVE and its associated clinical risk factors.

METHODS

This retrospective study was conducted in two hospitals in southern Taiwan. Patients with phenotypically vancomycin-susceptible E. faecium bacteremia were enrolled between 2017 and 2021. VVEs were defined as isolates harboring the vanA gene that were phenotypically susceptible to vancomycin. Vancomycin-susceptible E. faecium (VSE) isolates were phenotypically susceptible to vancomycin and lacked vanA or vanB genes.

RESULTS

Of the 142 enrolled patients, 121 (85.2%) had VSE and 21 (14.8%) had VVE. Resistance rates to penicillin, tetracycline, and fosfomycin were higher in VVE isolates. Malignancy (adjusted odds ratio [aOR] = 4.87; 95% confidence interval [CI] 1.54-15.41, p = 0.007) and central venous catheter usage (aOR = 4.69; 95% CI 1.49-14.78, p = 0.008) were the independent risk factors associated with VVE bacteremia. Being male (aOR = 0.12, CI 0.03-0.44, p = 0.002) was less likely to be associated with VVE bacteremia. Although VVE was not associated with 30-day mortality (38.1% [VVE] vs. 35.5% [VSE], p = 0.822), one case of subsequent vancomycin-resistant enterococci infection in the VVE group with vancomycin treatment (4.8%, 1/21) was identified, which led to subsequent mortality.

CONCLUSIONS

The prevalence of VVE was high among E. faecium isolates with vancomycin-susceptible phenotypes in southern Taiwan. Although the current study revealed that VVE bacteremia was not associated with poor clinical outcome, further multicenter surveillance survey is recommended to evaluate the possible impact of VVE on public health in Taiwan.

Ceftazidime-avibactam versus other antimicrobial agents for treatment of Multidrug-resistant Pseudomonas aeruginosa: a systematic review and meta-analysis

OBJECTIVES

Multidrug-resistant Pseudomonas aeruginosa (MDR-PA) is a life-threatening infection with limited treatment options. This is the first meta-analysis of recently published data to compare the clinical outcomes of ceftazidime-avibactam (CAZ-AVI) with other antimicrobial agents in treating MDR-PA infections.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Embase and the Cochrane Library have been systematically reviewed, for publications in the English language, from database inception to July 2023.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies comparing CAZ-AVI outcomes with other antimicrobial agents were included. In-hospital mortality & 30-day mortality were assessed as the main outcomes.

DATA EXTRACTION AND SYNTHESIS

Literature screening, data extraction, and the quality evaluation of studies were conducted by two researchers independently, with disagreements resolved by another researcher. The Newcastle-Ottawa Scale was used to assess the bias risk for the included studies. Review Manager V.5.4 was employed for the meta-analysis.

RESULTS

The meta-analysis included four retrospective studies, enrolling 1934 patients. The CAZ-AVI group demonstrated significantly lower in-hospital mortality (risk ratio (RR) = 0.60, 95% CI:0.37-0.97, I2 = 74%, p = 0.04) in three studies with 1444 patients and lower 30-day mortality, in 438 patients from three studies (RR = 0.54, 95% CI:0.28-1.05, I2 = 67%, p = 0.07). No significant difference in clinical success, microbiological success, length of hospital, and ICU stay was observed.

CONCLUSIONS

This meta-analysis demonstrated that CAZ-AVI treatment significantly lowered in-hospital mortality compared with other antimicrobial agents in MDR-PA infections. However, the analysis only included a few observational studies and high-quality, randomized controlled trials are needed to investigate further the scope of CAZ-AVI in MDR-PA  infections.

Persistence of Daptomycin-Resistant and Vancomycin-Resistant Enterococci in Hospitalized Patients with Underlying Malignancies: A 7-Year Follow-Up Study

Vancomycin-resistant enterococci (VRE) commonly colonize the gut of individuals with hematologic malignancies or undergoing hematopoietic cell transplant (HCT) and may cause bacteremia. In 2012, we identified VRE isolates from patients and patients' rooms and showed transmission networks of highly genetically related daptomycin-resistant (DR)-VRE strains. This is a follow-up study performing whole-genome sequencing (WGS) and phylogenetic analyses on 82 clinical VRE strains isolated from stools and blood cultures of patients with leukemia and HCT between 2015 and 2019. Here, we observed transmission of highly genetically related strains between rooms on the same or on different floors, including a DR-VRE strain identified in 2012. Eleven of twenty-eight patients with DR-VRE were never exposed to daptomycin, suggesting horizontal transmission. Fifteen of the twenty-eight patients with DR-VRE died within 30 days of positive blood cultures. Amongst those, one DR-VRE strain belonging to ST1471 had the virulence gene bopD responsible for biofilm formation. Additionally, to our knowledge, this is the first report of a DR-VRE strain belonging to ST323 in the United States. In summary, our study demonstrated the emergence and persistence of VRE strains, especially DR-VRE, in our hospital. Adding WGS to routine infection control measures may timely identify potential horizontal VRE transmission including multi-drug-resistant isolates.

Efficacy of short- versus prolonged-courses of antimicrobial therapy for carbapenem-resistant Klebsiella pneumoniae bloodstream infections: A propensity score-matched cohort study

BACKGROUND

As limited antibiotic options are available for the treatment of carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infections (BSIs), the optimal treatment duration for CRKP BSIs is unclear. Our objective was to investigate whether short courses (6-10 days) are as effective as prolonged courses (≥11 days) of active antibiotic therapy for CRKP BSIs.

METHODS

A retrospective cohort study comprising adults with monomicrobial CRKP BSI receiving a short or prolonged course of in vitro active therapy at a medical center was conducted between 2010 and 2021. Comparisons of two therapeutic strategies were assessed by the logistic regression model and propensity score analysis. The primary endpoint was 30-day crude mortality. Secondary outcomes included recurrent BSIs, the emergence of multidrug-resistant organisms and candidemia during hospitalization after completing antibiotic therapy for CRKP BSIs.

RESULTS

Of 263 eligible adults, 160 (60.8%) were male, and the median (interquartile range) age was 69.0 (53.0-76.0) years. Common comorbidities included diabetes (143 patients, 54.4%), malignancy (75, 28.5%), cerebrovascular accident (58, 22.1%), and hemodialysis (49, 18.6%). The 30-day mortality rate was 8.4% (22 patients). Of 84 propensity score well-balanced matched pairs, the 30-day mortality was similar in the short-course and prolonged-course group (6.0% and 7.1%, respectively; P = 1.00). However, there were less episodes candidemia in the short-course group (1.2% versus 13.1%; odds ratio, 0.08; 95% confidence interval, 0.01-0.63; P = 0.005).

CONCLUSION

Short courses of active therapy for CRKP BSIs demonstrate comparable clinical outcomes to prolonged courses and are associated with a lower risk of subsequent candidemia.

The real-world impact of the BioFire FilmArray blood culture identification 2 panel on antimicrobial stewardship among patients with bloodstream infections in intensive care units with a high burden of drug-resistant pathogens

BACKGROUND

The increasing prevalence of drug-resistant pathogens leads to delays in adequate antimicrobial treatment in intensive care units (ICU). The real-world influence of the BioFire FilmArray Blood Culture Identification 2 (BCID2) panel on pathogen identification, diagnostic concordance with conventional culture methods, and antimicrobial stewardship in the ICU remains unexplored.

METHODS

This retrospective observational study, conducted from July 2021 to August 2023, involved adult ICU patients with positive blood cultures who underwent BCID2 testing. The concordance between BCID2 and conventional culture results was examined, and its impact on antimicrobial stewardship was assessed through a comprehensive retrospective review of patient records by intensivists.

RESULTS

A total of 129 blood specimens from 113 patients were analysed. Among these patients, a high proportion of drug-resistant strains were noted, including carbapenem-resistant Klebsiella pneumoniae (CRKP) (57.1%), carbapenem-resistant Acinetobacter calcoaceticus-baumannii complex (100%), methicillin-resistant Staphylococcus aureus (MRSA) (70%), and vancomycin-resistant Enterococcus faecium (VRE) (100%). The time from blood culture collection to obtaining BCID2 results was significantly shorter than conventional culture (46.2 h vs. 86.9 h, p < 0.001). BCID2 demonstrated 100% concordance in genotype-phenotype correlation in antimicrobial resistance (AMR) for CRKP, carbapenem-resistant Escherichia coli, MRSA, and VRE. A total of 40.5% of patients received inadequate empirical antimicrobial treatment. The antimicrobial regimen was adjusted or confirmed in 55.4% of patients following the BCID2 results.

CONCLUSIONS

In the context of a high burden of drug-resistant pathogens, BCID2 demonstrated rapid pathogen and AMR detection, with a noticeable impact on antimicrobial stewardship in BSI in the ICU.

Clinical outcomes of carbapenem-resistant gram-negative bacterial bloodstream infection in patients with end-stage renal disease in intensive care units: a multicenter retrospective observational study

BACKGROUND

Carbapenem-resistant gram-negative bacteria (CRGNB) present a considerable global threat due to their challenging treatment and increased mortality rates, with bloodstream infection (BSI) having the highest mortality rate. Patients with end-stage renal disease (ESRD) undergoing renal replacement therapy (RRT) face an increased risk of BSI. Limited data are available regarding the prognosis and treatment outcomes of CRGNB-BSI in patients with ESRD in intensive care units (ICUs).

METHODS

This multi-center retrospective observational study included a total of 149 ICU patients with ESRD and CRGNB-BSI in Taiwan from January 2015 to December 2019. Clinical and microbiological outcomes were assessed, and multivariable regression analysis was used to evaluate the independent risk factors for day-28 mortality and the impact of antimicrobial therapy regimen on treatment outcomes.

RESULTS

Among the 149 patients, a total of 127 patients (85.2%) acquired BSI in the ICU, with catheter-related infections (47.7%) and pneumonia (32.2%) being the most common etiologies. Acinetobacter baumannii (49.0%) and Klebsiella pneumoniae (31.5%) were the most frequently isolated pathogens. The day-28 mortality rate from BSI onset was 52.3%, and in-hospital mortality was 73.2%, with survivors experiencing prolonged hospital stays. A higher Sequential Organ Failure Assessment (SOFA) score (adjusted hazards ratio [aHR], 1.25; 95% confidence interval [CI] 1.17-1.35) and shock status (aHR, 2.12; 95% CI 1.14-3.94) independently predicted day-28 mortality. Colistin-based therapy reduced day-28 mortality in patients with shock, a SOFA score of ≥ 13, and Acinetobacter baumannii-related BSI.

CONCLUSIONS

CRGNB-BSI led to high mortality in critically ill patients with ESRD. Day-28 mortality was independently predicted by a higher SOFA score and shock status. In patients with higher disease severity and Acinetobacter baumannii-related BSI, colistin-based therapy improved treatment outcomes.

Knowledge, attitude, and practice towards bacterial multidrug-resistance and structural equation modeling analysis among intensive care unit nurses and physicians

BACKGROUND

The intensive care unit (ICU) is a department with a high risk of MDR bacteria, and ICU nurses and physicians play critical roles in bacterial multidrug resistance (MDR) prevention.

OBJECTIVES

To explore the knowledge, attitudes, and practice (KAP) towards bacterial MDR among ICU nurses and physicians.

METHODS

A self-designed questionnaire was administered to collect data. Structural equation modeling (SEM) was applied to assess the associations among study variables.

RESULTS

A total of 369 questionnaires were collected; 43 questionnaires were excluded due to self-contradictory on the trap question or the obviously repeated pattern. Finally, 326 (88.35%) valid questionnaires were included in the analysis. The knowledge, attitudes, and practice were 13.57 ± 1.69 (90.47%, possible range: 0-15), 38.75 ± 2.23 (96.88%, possible range: 8-40), and 47.40 ± 3.59 (94.80%, possible range: 10-50). The SEM showed that knowledge had a direct effect on attitude with a direct effect value of 0.61 (P < 0.001) and a direct negative effect on practice with a direct effect value of -0.30 (P = 0.009). The direct effect of attitude on practice was 0.89 (P < 0.001); the indirect effect of knowledge through attitude on practice was 0.52 (P < 0.001). Job satisfaction had a direct effect on attitude and practice, with an effect value of 0.52 (P = 0.030) and 0.75 (P = 0.040). Being a physician (OR = 0.354, 95%CI: 0.159-0.790, P = 0.011), 5-9.9 years of practice (OR = 4.534, 95%CI: 1.878-8.721, P < 0.001), and ≥ 10 years of practice (OR = 3.369, 95%CI: 1.301-8.721, P = 0.012) were independently associated with good knowledge. The attitude scores (OR = 1.499, 95%CI: 1.227-1.830, P < 0.001), male gender (OR = 0.390, 95%CI: 0.175-0.870, P = 0.022), and 5-9.9 years of experience (OR = 0.373, 95%CI: 0.177-0.787, P = 0.010) were independently associated with proactive practice.

CONCLUSION

Nurses and physicians in the ICU showed good knowledge, positive attitudes, and proactive practice toward bacterial MDR. Nurses and physicians' knowledge had a direct effect on their attitude, while attitude might directly influence the practice and also play a mediating role between knowledge and practice. Job satisfaction might directly support the positive attitude and practice toward bacterial MDR.

International guidelines for the treatment of carbapenem-resistant Gram-negative Bacilli infections: A comparison and evaluation

OBJECTIVES

This study aimed to appraise clinical practice guidelines (CPGs) for the treatment of carbapenem-resistant Gram-negative Bacilli (CRGNB) infections and to summarise the recommendations.

METHODS

A systematic search of the literature published from January 2012 to March 2023 was undertaken to identify CPGs related to CRGNB infections treatment. The methodological and reporting quality of eligible CPGs were assessed using six domains of the Appraisal of Guidelines for Research and Evaluation (AGREE) II tool and seven domains of the Reporting Items for practice Guidelines in HealThcare (RIGHT) checklist. Basic information and recommendations of included CPGs were extracted and compared.

RESULTS

A total of 21 CPGs from 7953 relevant articles were included. The mean overall AGREE II score was 62.7%, and was highest for "clarity of presentation" (90.2%) and lowest for "stakeholder involvement" (44.8%). The overall reporting quality of all of the CPGs was suboptimal, with the proportion of eligible items ranging from 45.7 to 85.7%. The treatment of CRGNB infections is related to the type of pathogen, the sensitivity of antimicrobial agents, and the site of infection. In general, the recommended options mainly included novel β-lactam/ β-lactamase inhibitors, cefiderocol, ampicillin-sulbactam (mainly for carbapenem-resistant Acinetobacter baumannii [CRAB]), and combination therapy, involving polymyxin B/colistin, tigecycline (except for carbapenem-resistant Pseudomonas aeruginosa), aminoglycosides, carbapenems, fosfomycin, and sulbactam (mainly for CRAB).

CONCLUSIONS

The methodological and reporting quality of CPGs for the treatment of CRGNB infections are generally suboptimal and need further improvement. Both monotherapy with novel drugs and combination therapy play important roles in the treatment.

Off-label Use of Ceftazidime/Avibactam in Neonatal Intensive Care Unit: A Real-life Experience and Literature Review

BACKGROUND

Multi/extensively drug-resistant bacterial infections have recently increased and new antimicrobial options are needed for difficult-to-treat infections. Ceftazidime/avibactam (CZA) has been approved for patients 3 months to 18 years of age, but real-life data on its off-label use in neonates and young infants are still scarce.

MATERIALS

We report demographic, clinical and microbiologic data as well as outcome and safety of all cases of infants treated with CZA between January 1, 2021 and September 30, 2022 in a tertiary neonatal intensive care unit. We also review all neonatal cases previously reported.

RESULTS

Twenty-one patients [17 males, with median gestational age 29 +2 (IQR 6 +6 ) weeks] received 31 CZA courses at a dose of 20-50 mg/kg/dose of ceftazidime q8h for suspected or proved multi/extensively drug-resistant infections. Median postnatal age at the onset of treatment was 44 days (IQR: 94 days). Twelve bacteremias, 2 urinary tract infections and 1 ventilator-acquired pneumonia were recorded. Twelve (39%) treatments were targeted, while 19 (61%) were empirically started due to known colonization with Klebsiella pneumoniae carbapenemase-producing Gram-negative bacteria. All patients had received multiple antibiotics prior and concomitantly with CZA. The most common pathogen identified at targeted administrations was carbapenem-resistant Klebsiella pneumoniae (83%). No serious adverse events attributed to the drug were detected. Twenty-one courses of CZA administration to 20 neonates with a median gestational age of 28.5 (IQR 3.5) weeks were previously reported without significant related adverse events.

CONCLUSIONS

Favorable clinical and microbiologic responses in neonatal intensive care unit patients treated with CZA off-label were observed without significant and unexpected adverse events in critically ill neonates.

Antimicrobial Susceptibility Profiles of Pasteurella multocida Isolates from Clinical Cases of Waterfowl in Hungary between 2022 and 2023

The waterfowl industry represents a narrow, yet economically significant, sector within the poultry industry. Although less prominent, the waterfowl sector is nonetheless of equal importance to any other livestock sector in terms of antimicrobial resistance and animal health issues. This study assesses the antimicrobial resistance profile of Pasteurella multocida bacterial strains isolated from clinical cases in Hungary's duck and goose populations, determining the minimal inhibitory concentration (MIC) of 27 samples collected from 15 different locations. The results indicate that the isolated strains were susceptible to most antibiotics, except for notable resistance to enrofloxacin. These findings support that Pasteurella multocida largely retained its susceptibility. However, the observed resistance to enrofloxacin suggests overuse of fluoroquinolones, which indicates the potential need for stricter regulation of their use in the poultry industry.

Epidemiology and antimicrobial susceptibility profiles of Enterobacterales causing bloodstream infections before and during COVID-19 pandemic: Results of the Study for Monitoring Antimicrobial Resistance Trends (SMART) in Taiwan, 2018-2021

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has contributed to the spread of antimicrobial resistance, including carbapenem-resistant Enterobacterales.

METHODS

This study utilized data from the Study for Monitoring Antimicrobial Resistance Trends (SMART) surveillance program in Taiwan. Enterobacterales from patients with bloodstream infections (BSIs) were collected and subjected to antimicrobial susceptibility testing and β-lactamase gene detection using a multiplex PCR assay. Statistical analysis was conducted to compare susceptibility rates and resistance genes between time periods before (2018-2019) and during the COVID-19 pandemic (2020-2021).

RESULTS

A total of 1231 Enterobacterales isolates were collected, predominantly Escherichia coli (55.6%) and Klebsiella pneumoniae (29.2%). The proportion of nosocomial BSIs increased during the COVID-19 pandemic (55.5% vs. 61.7%, p < 0.05). Overall, susceptibility rates for most antimicrobial agents decreased, with Enterobacterales from nosocomial BSIs showing significantly lower susceptibility rates than those from community-acquired BSIs. Among 123 Enterobacterales isolates that underwent molecular resistance mechanism detection, ESBL, AmpC β-lactamase, and carbapenemase genes were detected in 43.1%, 48.8% and 16.3% of the tested isolates, respectively. The prevalence of carbapenemase genes among carbapenem-resistant Enterobacterales increased during the pandemic, although the difference was not statistically significant. Two novel β-lactamase inhibitor combinations, imipenem-relebactam and meropenem-vaborbactam, preserved good efficacy against Enterobacterales. However, imipenem-relebactam showed lower in vitro activity against imipenem-non-susceptible Enterobacterales than that of meropenem-vaborbactam.

CONCLUSIONS

The COVID-19 pandemic appears to be associated with a general decrease in antimicrobial susceptibility rates among Enterobacterales causing BSIs in Taiwan. Continuous surveillance is crucial to monitor antimicrobial resistance during the pandemic and in the future.

Bacterial Infections in Intensive Care Units: Epidemiological and Microbiological Aspects

Intensive care units constitute a critical setting for the management of infections. The patients' fragilities and spread of multidrug-resistant microorganisms lead to relevant difficulties in the patients' care. Recent epidemiological surveys documented the Gram-negative bacteria supremacy among intensive care unit (ICU) infection aetiologies, accounting for numerous multidrug-resistant isolates. Regarding this specific setting, clinical microbiology support holds a crucial role in the definition of diagnostic algorithms. Eventually, the complete patient evaluation requires integrating local epidemiological knowledge into the best practice and the standardization of antimicrobial stewardship programs. Clinical laboratories usually receive respiratory tract and blood samples from ICU patients, which express a significant predisposition to severe infections. Therefore, conventional or rapid diagnostic workflows should be modified depending on patients' urgency and preliminary colonization data. Additionally, it is essential to complete each microbiological report with rapid phenotypic minimum inhibitory concentration (MIC) values and information about resistance markers. Microbiologists also help in the eventual integration of ultimate genome analysis techniques into complicated diagnostic workflows. Herein, we want to emphasize the role of the microbiologist in the decisional process of critical patient management.

Supernatant of platelet-Klebsiella pneumoniae coculture induces apoptosis-like death in Klebsiella pneumoniae

Multidrug-resistant Klebsiella pneumoniae strains, especially carbapenem-resistant K. pneumoniae, have become a rapidly emerging crisis worldwide, greatly limiting current therapeutic options and posing new challenges to infection management. Therefore, it is imperative to develop novel and effective biological agents for the treatment of multidrug-resistant K. pneumoniae infections. Platelets play an important role in the development of inflammation and immune responses. The main component responsible for platelet antibacterial activity lies in the supernatant stimulated by gram-positive bacteria. However, little research has been conducted on the interaction of gram-negative bacteria with platelets. Therefore, we aimed to explore the bacteriostatic effect of the supernatant derived from platelet-K. pneumoniae coculture and the mechanism underlying this effect to further assess the potential of platelet-bacterial coculture supernatant. We conducted this study on the gram-negative bacteria K. pneumoniae and CRKP and detected turbidity changes in K. pneumoniae and CRKP cultures when grown with platelet-K. pneumoniae coculture supernatant added to the culture medium. We found that platelet-K. pneumoniae coculture supernatant significantly inhibited the growth of K. pneumoniae and CRKP in vitro. Furthermore, transfusion of platelet-K. pneumoniae coculture supernatant alleviated the symptoms of K. pneumoniae and CRKP infection in a murine model. Additionally, we observed apoptosis-like changes, such as phosphatidylserine exposure, chromosome condensation, DNA fragmentation, and overproduction of reactive oxygen species in K. pneumoniae following treatment with the supernatant. Our study demonstrates that the platelet-K. pneumoniae coculture supernatant can inhibit K. pneumoniae growth by inducing an apoptosis-like death, which is important for the antibacterial strategies development in the future.IMPORTANCEWith the widespread use of antibiotics, bacterial resistance is increasing, and a variety of multi-drug resistant Gram-negative bacteria have emerged, which brings great challenges to the treatment of infections caused by Gram-negative bacteria. Therefore, finding new strategies to inhibit Gram-negative bacteria and even multi-drug- resistant Gram-negative bacteria is crucial for treating infections caused by Gram-negative bacteria, improving the abuse of antibiotics, and maintaining the balance between bacteria and antibiotics. K. pneumoniae is a common clinical pathogen, and drug-resistant CRKP is increasingly difficult to cure, which brings great clinical challenges. In this study, we found that the platelet-K. pneumoniae coculture supernatant can inhibit K. pneumoniae growth by inducing an apoptosis-like death. This finding has inspired the development of future antimicrobial strategies, which are expected to improve the clinical treatment of Gram-negative bacteria and control the development of multidrug-resistant strains.

Rising role of 3D-printing in delivery of therapeutics for infectious disease

Modern drug delivery to tackle infectious disease has drawn close to personalizing medicine for specific patient populations. Challenges include antibiotic-resistant infections, healthcare associated infections, and customizing treatments for local patient populations. Recently, 3D-printing has become a facilitator for the development of personalized pharmaceutic drug delivery systems. With a variety of manufacturing techniques, 3D-printing offers advantages in drug delivery development for controlled, fine-tuned release and platforms for different routes of administration. This review summarizes 3D-printing techniques in pharmaceutics and drug delivery focusing on treating infectious diseases, and discusses the influence of 3D-printing design considerations on drug delivery platforms targeting these diseases. Additionally, applications of 3D-printing in infectious diseases are summarized, with the goal to provide insight into how future delivery innovations may benefit from 3D-printing to address the global challenges in infectious disease.

Risk factors for acute kidney injury associated with intravenous vancomycin in neurosurgical inpatients: a retrospective study

PURPOSE

Vancomycin (VAN) is widely used in neurosurgical patients for intracranial infections. We aimed to assess the incidence and risk factors for VAN-associated acute kidney injury (VA-AKI) in this population.

METHODS

A case-control study of patients who treated with vancomycin in neurosurgery from January 2020 to December 2022 was conducted. Demographics and potential risk factors were collected. Multivariate logistic regression analyses were performed to identify risk factors for VA-AKI. AKI was defined according to the Kidney Disease Improving Global Outcomes Guidelines (KDIGO).

RESULTS

A total of 345 patients participated with a VA-AKI incidence of 17.1% (59 cases). Among them, 15 patients had renal impairment (Stage 2 or higher), and 2 required dialysis. With univariate analysis and binary logistic regression analysis, we found that the use of mannitol (OR: 4.164; 95% CI: 1.606-10.792; P = 0.003), loop diuretics (OR: 3.371; 95% CI: 1.633-6.958; P = 0.001), three or more antimicrobial applications (OR: 3.623; 95% CI: 1.600-8.206; P = 0.002), diastolic blood pressure 80-89 mm Hg (OR: 5.532; 95% CI: 1.677-18.250; P = 0.005) and diastolic blood pressure ≥ 90 mm Hg (OR: 6.845; 95% CI: 1.518-30.866; P = 0.012) were independent risk factors for VA-AKI. In addition, according to the Youden Index, the trough concentration of vancomycin should not exceed 15.845 mg/L.

CONCLUSION

The incidence of VA-AKI in neurosurgical patients was 17.1%. The concomitant use of mannitol and loop diuretics, along with higher diastolic blood pressure and the combined use of more than three antimicrobial agents, were associated with an increased risk of neurosurgical VA-AKI.

Acute kidney injury should not be neglected - optimization of quick Pitt bacteremia score for predicting mortality in critically ill patients with bloodstream infection: a retrospective cohort study

Background

Considering the therapeutic difficulties and mortality associated with bloodstream infection (BSI), it is essential to investigate other potential factors affecting mortality in critically ill patients with BSI and examine the utility of the quick Pitt bacteremia (qPitt) score to improve the survival rate.

Objectives

To improve the predictive accuracy of the qPitt scoring system by evaluating the five current components of qPitt and including other potential factors influencing mortality in critically ill patients with BSI.

Design

This was a retrospective cohort study.

Methods

Medical information from the Medical Information Mart for Intensive Care IV database was used in this retrospective cohort study. The risk factors associated with mortality were examined using a multivariate logistic regression model. The area under the receiver operating characteristic curve (AUC) was used to assess the discriminatory capability of the prediction models.

Results

In total, 1240 eligible critically ill patients with BSI were included. After adjustment for age, community-onset BSI, indwelling invasive lines, and Glasgow Coma Scale (GCS) ⩽ 8, acute kidney injury (AKI) was identified as a notable risk factor for 14-day mortality. Except for altered mental status, the four other main components of the original qPitt were significantly associated with 14-day mortality. Hence, we established a modified qPitt (m-qPitt) by adding AKI and replacing altered mental status with GCS ⩽ 8. The AUCs for m-qPitt and qPitt were 0.723 [95% confidence interval (CI): 0.683-0.759] and 0.708 (95% CI: 0.669-0.745) in predicting 14-day mortality, respectively. Moreover, m-qPitt also had acceptable performance and discrimination power [0.700 (95% CI: 0.666-0.732)] in predicting 28-day mortality.

Conclusion

AKI significantly influenced the survival of critically ill patients with BSIs. Compared with the original qPitt, our new m-qPitt was proven to have a better predictive performance for mortality in critically ill patients with BSI. Further studies should be conducted to validate the practicality of m-qPitt.

Emerging infections in vulnerable hosts: Stenotrophomonas maltophilia and Elizabethkingia anophelis

PURPOSE OF REVIEW

This systematic review aimed to explore the recent trends in the epidemiology, risk factors, and antimicrobial susceptibility of two emerging opportunistic pathogens, Stenotrophomonas maltophilia and Elizabethkingia anophelis .

RECENT FINDINGS

Since 2020, numerous outbreaks of S. maltophilia and E. anophelis have been reported worldwide. Most of these outbreaks have been associated with healthcare facilities, although one outbreak caused by E. anophelis in France was considered a community-associated infection. In terms of antimicrobial susceptibility, trimethoprim/sulfamethoxazole (TMP-SMZ), levofloxacin, and minocycline have exhibited good efficacy against S. maltophilia . Additionally, cefiderocol and a combination of aztreonam and avibactam have shown promising results in in vitro susceptibility testing. For E. anophelis , there is currently no consensus on the optimal treatment. Although some studies have reported good efficacy with rifampin, TMP-SMZ, piperacillin/tazobactam, and cefoperazone/sulbactam, minocycline had the most favourable in vitro susceptibility rates. Cefiderocol may serve as an alternative due to its low minimum inhibitory concentration (MIC) against E. anophelis . The role of vancomycin in treatment is still uncertain, although several successful cases with vancomycin treatment, even with high MIC values, have been reported.

SUMMARY

Immunocompromised patients are particularly vulnerable to infections caused by S. maltophilia and E. anophelis , but the optimal treatment strategy remains inconclusive. Further research is necessary to determine the most effective use of conventional and novel antimicrobial agents in combatting these multidrug-resistant pathogens.

Establishment and Validation of Models for the Risk of Multi-Drug Resistant Bacteria Infection and Prognosis in Elderly Patients with Pulmonary Infection: A Multicenter Retrospective Study

Purpose

The aim of this study was to establish risk prediction and prognosis models for multidrug-resistant bacterial infections (MDRB) in elderly patients with pulmonary infections in a multicenter setting.

Patients and Methods

This study is a retrospective cohort analysis in Anhui province of China. Data dimension reduction and feature selection were performed using the lasso regression model. Multifactorial regression analysis to identify risk factors associated with MDRB infection and prognosis. The relevant risks of each patient in the prognostic training cohort were scored based on prognostic independent risk factors. Subsequently, patients were classified into high-risk and low-risk groups, and survival differences were compared between them. Finally, models were established based on independent risk factors for infection, risk groups, and independent prognostic factors, and were presented on nomograms. The predictive accuracy of the model was assessed using corresponding external validation set data.

Results

The study cohort comprised 994 elderly patients with pulmonary infection. Multivariate analysis revealed that endotracheal intubation, previous antibiotic use beyond 2 weeks, and concurrent respiratory failure or cerebrovascular disease were independent risk factors associated with the incidence of MDRB infection. Cox regression analysis identified respiratory failure, malnutrition, an APACHE II score of at least 20, and higher blood creatinine levels as independent prognostic risk factors. The models were validated using an external validation dataset from multiple centers, which demonstrated good diagnostic ability and a good fit with a fair benefit.

Conclusion

In conclusion, our study provides an appropriate and generalisable assessment of risk factors affecting infection and prognosis in patients with MDRB, contributing to improved early identification of patients at higher risk of infection and death, and appropriately guiding clinical management.

Isolation and characterization of bacteriophages with activities against multi-drug-resistant Acinetobacter nosocomialis causing bloodstream infection in vivo

BACKGROUND

Acinetobacter nosocomialis (A. nosocomialis) is a glucose non-fermentative, gram-negative bacillus that belongs to the Acinetobacter calcoaceticus-baumannii complex. In recent years, studies have found an increased clinical prevalence of A. nosocomialis. However, given the increasing trend of antibiotic resistance, developing new antibacterial agents is vital. Currently, research regarding bacteriophage therapy against A. nosocomialis is only limited.

METHODS

Two A. nosocomialis bacteriophages, TCUAN1 and TCUAN2, were isolated from sewage. Experiments such as transmission electron microscopy (TEM), host-range analysis, and sequencing were performed to determine their biological and genomic characteristics. TCUAN2 were further subjected to in vivo experiments and their derived-endolysin were cloned and tested against their bacteria host.

RESULTS

Transmission electron microscopy revealed that TCUAN1 and TCUAN2 belong to Myoviridae and Podoviridae, respectively. Both phages show a broad host spectrum and rapid adsorption efficiency. Further biological analysis showed that TCUAN2 possesses a shorter latent period and larger burst size compared to TCUAN1. Because TCUAN2 showed a better antibacterial activity, it was injected into A. nosocomialis-infected mice which resulted in a significant decrease in bacterial load levels in the blood and increased the mice's survival. Finally, genomic analysis revealed that the complete nucleotide sequence of TCUAN1 is 49, 691 bps (containing 75 open reading frames) with a G + C content of 39.3%; whereas the complete nucleotide sequence of TCUAN2 is 41, 815 bps (containing 68 open reading frames) with a G + C content of 39.1%. The endolysin gene cloned and purified from TCUAN2 also showed antibacterial activity when used with a chelator EDTA.

Geographical patterns of in vitro susceptibilities to tigecycline and colistin among worldwide isolates of Acinetobacter baumannii, Escherichia coli and Klebsiella pneumoniae: Data from the Antimicrobial Testing Leadership and Surveillance (ATLAS) programme, 2016-2021

This study aimed to investigate the geographical trends of minimum inhibitory concentrations (MICs) for tigecycline and colistin in Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae isolates which were collected for the Antimicrobial Testing Leadership and Surveillance (ATLAS) programme from 2016-2021. MICs of the isolates were determined using the broth microdilution method. In the study period, there was an increase in MIC50 and MIC90 values in Asia for tigecycline MICs in A. baumannii isolates, and the geometric mean of MICs increased significantly from 0.51-0.96 (R2 value of 0.912). The isolates in Europe and Latin America also showed an increase in the geometric mean, but the percentage of MIC values ≤ 2 mg/L decreased from 99.7% to 86.7% in Asia. Among the Asian countries studied, China (90.9%), Thailand (94.3%), and Malaysia (95.5%) showed the lower percentages of tigecycline MIC values ≤0.5 mg/L for E. coli isolates. In terms of colistin susceptibility among A. baumannii isolates, there was no increase in MIC50/ MIC90 or the geometric mean from 2016-2021. Compared to other continents, A. baumannii isolates in Europe had the highest MIC50 (0.5 mg/L), MIC90 (2 mg/L), and geometric mean (0.55 mg/L). For E. coli, the percentage of colistin MIC values ≤2 mg/L was consistently >98% in the study areas from 2016-2021. Among K. pneumoniae isolates, Europe and Latin America had higher geometric means of MICs (0.41 and 0.4 mg/L, respectively) and lower percentages of colistin MICs ≤2 mg/L than those in the other continents.

Antimicrobial Susceptibility of E. coli Isolates from Intra-Abdominal Infections in the Asia-Pacific Region: Trends in Ciprofloxacin, Ceftriaxone, Cefepime, and Piperacillin/Tazobactam Susceptibility

Purpose

To investigate the antibiotic susceptibility of Escherichia coli isolates in patients diagnosed with intra-abdominal infections (IAIs) in the Asia-Pacific region.

Patients and Methods

This study was conducted at 50 medical hospitals across 9 countries/regions as part of the Study for Monitoring Antimicrobial Resistance Trends (SMART) surveillance program from 2014 to 2018. Nonduplicate isolates of aerobic and facultative gram-negative bacilli were collected and processed for further antimicrobial susceptibility testing.

Results

A total of 10,709 isolates were collected, with E. coli (n=4737, 44.2%) being the leading pathogen causing IAIs, followed by Klebsiella pneumoniae (n=2429, 22.7%) and Pseudomonas aeruginosa (n=931, 8.7%). Community-associated (CA) E. coli isolates generally exhibited higher susceptibility rates for most antibiotics than hospital-associated (HA) isolates. In countries/regions other than Hong Kong, South Korea, and Singapore, HA isolates displayed lower susceptibility rates for multiple classes (≥4) of antibiotics. Among the commonly used antibiotics in IAIs, the overall susceptibility rate for ciprofloxacin was low, with an average of 41.3%. Ceftriaxone susceptibility rates in all selected countries were below 80% starting in 2018, ranging from 23.3% to 75.8%. The cefepime susceptibility rates varied across regions, with consistently reduced susceptibility ranging from 45.5% to 57.8% in India, Thailand, and Vietnam. Piperacillin/tazobactam demonstrated effectiveness against E. coli isolates in almost all countries except India, with a downward trend observed in the Philippines and Taiwan. Carbapenems remained effective against more than 90% of E. coli isolates, except in India.

Conclusion

Prudent use of fluoroquinolones and ceftriaxone is advised when treating both CA and HA IAIs in the Asia-Pacific region. The low susceptibility rate of cefepime in India, Thailand, and Vietnam needs careful consideration in its administration. Moreover, the increase in nonsusceptibility to piperacillin/tazobactam in the Philippines and Taiwan poses a potential risk that should be closely monitored.

Guidelines for the diagnosis, treatment, prevention and control of infections caused by carbapenem-resistant gram-negative bacilli

The dissemination of carbapenem-resistant Gram-negative bacilli (CRGNB) is a global public health issue. CRGNB isolates are usually extensively drug-resistant or pandrug-resistant, resulting in limited antimicrobial treatment options and high mortality. A multidisciplinary guideline development group covering clinical infectious diseases, clinical microbiology, clinical pharmacology, infection control, and guideline methodology experts jointly developed the present clinical practice guidelines based on best available scientific evidence to address the clinical issues regarding laboratory testing, antimicrobial therapy, and prevention of CRGNB infections. This guideline focuses on carbapenem-resistant Enterobacteriales (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB), and carbapenem-resistant Pseudomonas aeruginosa (CRPA). Sixteen clinical questions were proposed from the perspective of current clinical practice and translated into research questions using PICO (population, intervention, comparator, and outcomes) format to collect and synthesize relevant evidence to inform corresponding recommendations. The grading of recommendations, assessment, development and evaluation (GRADE) approach was used to evaluate the quality of evidence, benefit and risk profile of corresponding interventions and formulate recommendations or suggestions. Evidence extracted from systematic reviews and randomized controlled trials (RCTs) was considered preferentially for treatment-related clinical questions. Observational studies, non-controlled studies, and expert opinions were considered as supplementary evidence in the absence of RCTs. The strength of recommendations was classified as strong or conditional (weak). The evidence informing recommendations derives from studies worldwide, while the implementation suggestions combined the Chinese experience. The target audience of this guideline is clinician and related professionals involved in management of infectious diseases.

The Challenge of Overcoming Antibiotic Resistance in Carbapenem-Resistant Gram-Negative Bacteria: "Attack on Titan"

The global burden of bacterial resistance remains one of the most serious public health concerns. Infections caused by multidrug-resistant (MDR) bacteria in critically ill patients require immediate empirical treatment, which may not only be ineffective due to the resistance of MDR bacteria to multiple classes of antibiotics, but may also contribute to the selection and spread of antimicrobial resistance. Both the WHO and the ECDC consider carbapenem-resistant Enterobacteriaceae (CRE), carbapenem-resistant Pseudomonas aeruginosa (CRPA), and carbapenem-resistant Acinetobacter baumannii (CRAB) to be the highest priority. The ability to form biofilm and the acquisition of multiple drug resistance genes, in particular to carbapenems, have made these pathogens particularly difficult to treat. They are a growing cause of healthcare-associated infections and a significant threat to public health, associated with a high mortality rate. Moreover, co-colonization with these pathogens in critically ill patients was found to be a significant predictor for in-hospital mortality. Importantly, they have the potential to spread resistance using mobile genetic elements. Given the current situation, it is clear that finding new ways to combat antimicrobial resistance can no longer be delayed. The aim of this review was to evaluate the literature on how these pathogens contribute to the global burden of AMR. The review also highlights the importance of the rational use of antibiotics and the need to implement antimicrobial stewardship principles to prevent the transmission of drug-resistant organisms in healthcare settings. Finally, the review discusses the advantages and limitations of alternative therapies for the treatment of infections caused by these "titans" of antibiotic resistance.

Resistance, Tolerance, Virulence and Bacterial Pathogen Fitness-Current State and Envisioned Solutions for the Near Future

The current antibiotic crisis and the global phenomena of bacterial resistance, inherited and non-inherited, and tolerance-associated with biofilm formation-are prompting dire predictions of a post-antibiotic era in the near future. These predictions refer to increases in morbidity and mortality rates as a consequence of infections with multidrug-resistant or pandrug-resistant microbial strains. In this context, we aimed to highlight the current status of the antibiotic resistance phenomenon and the significance of bacterial virulence properties/fitness for human health and to review the main strategies alternative or complementary to antibiotic therapy, some of them being already clinically applied or in clinical trials, others only foreseen and in the research phase.

Influences of Initial Empiric Antibiotics with Ampicillin plus Cefotaxime on the Outcomes of Neonates with Respiratory Failure: A Propensity Score Matched Analysis

Background: Empiric antibiotics are often prescribed in critically ill and preterm neonates at birth until sepsis can be ruled out. Although the current guideline suggests narrow-spectrum antibiotics, an upgrade in antibiotics is common in the neonatal intensive care unit. The impacts of initial broad-spectrum antibiotics on the outcomes of critically ill neonates with respiratory failure requiring mechanical intubation have not been well studied. Methods: A total of 1162 neonates from a tertiary level neonatal intensive care unit (NICU) in Taiwan who were on mechanical ventilation for respiratory distress/failure at birth were enrolled, and neonates receiving ampicillin plus cefotaxime were compared with those receiving ampicillin plus gentamicin. Propensity score-matched analysis was used to investigate the effects of ampicillin plus cefotaxime on the outcomes of critically ill neonates. Results: Ampicillin plus cefotaxime was more frequently prescribed for intubated neonates with lower birth weight, higher severity of illness, and those with a high risk of early-onset sepsis. Only 11.1% of these neonates had blood culture-confirmed early-onset sepsis and/or congenital pneumonia. The use of ampicillin plus cefotaxime did not significantly contribute to improved outcomes among neonates with early-onset sepsis. After propensity score-matched analyses, the critically ill neonates receiving ampicillin plus cefotaxime had significantly worse outcomes than those receiving ampicillin plus gentamicin, including a higher risk of late-onset sepsis caused by multidrug-resistant pathogens (11.2% versus 7.1%, p = 0.027), longer duration of hospitalization (median [IQR], 86.5 [47-118.8] days versus 78 [45.0-106.0] days, p = 0.002), and a significantly higher risk of in-hospital mortality (14.2% versus 9.6%, p = 0.023). Conclusions: Ampicillin plus cefotaxime should not be routinely prescribed as the empiric antibiotics for critically ill neonates at birth because they were associated with a higher risk of infections caused by multidrug-resistant pathogens and final worse outcomes.

Synergy between Human Peptide LL-37 and Polymyxin B against Planktonic and Biofilm Cells of Escherichia coli and Pseudomonas aeruginosa

The rise in antimicrobial resistant bacteria is limiting the number of effective treatments for bacterial infections. Escherichia coli and Pseudomonas aeruginosa are two of the pathogens with the highest prevalence of resistance, and with the greatest need for new antimicrobial agents. Combinations of antimicrobial peptides (AMPs) and antibiotics that display synergistic effects have been shown to be an effective strategy in the development of novel therapeutic agents. In this study, we investigated the synergy between the AMP LL-37 and various classes of antibiotics against E. coli and P. aeruginosa strains. Of the six antibiotics tested (ampicillin, tetracycline, ciprofloxacin, gentamicin, aztreonam, and polymyxin B (PMB)), LL-37 displayed the strongest synergy against E. coli MG1655 and P. aeruginosa PAO1 laboratory strains when combined with PMB. Given the strong synergy, the PMB + LL-37 combination was chosen for further examination where it demonstrated synergy against multidrug-resistant and clinical E. coli isolates. Synergy of PMB + LL-37 towards clinical isolates of P. aeruginosa varied and showed synergistic, additive, or indifferent effects. The PMB + LL-37 combination treatment showed significant prevention of biofilm formation as well as eradication of pre-grown E. coli and P. aeruginosa biofilms. Using the Galleria mellonella wax worm model, we showed that the PMB + LL-37 combination treatment retained its antibacterial capacities in vivo. Flow analyses were performed to characterize the mode of action. The results of the present study provide proof of principle for the synergistic response between LL-37 and PMB and give novel insights into a promising new antimicrobial combination against gram-negative planktonic and biofilm cells.

Geographic patterns of carbapenem-resistant, multi-drug-resistant and difficult-to-treat Acinetobacter baumannii in the Asia-Pacific region: results from the Antimicrobial Testing Leadership and Surveillance (ATLAS) program, 2020

This study evaluated the in-vitro activity of multiple classes of antibiotics, including novel β-lactam combination agents, tigecycline and colistin, against carbapenem-resistant (CRAB), multi-drug-resistant (MDRAB) and difficult-to-treat (DTRAB) Acinetobacter baumannii. Minimum inhibitory concentrations (MICs) were determined using the broth microdilution method. Susceptibility profiles and the distribution of selected antimicrobials among countries were illustrated and examined based on the breakpoints of the Clinical and Laboratory Standards Institute, European Committee on Antimicrobial Susceptibility Testing and the US Food and Drug Administration. In total, 847 A. baumannii isolates were evaluated, and 692 isolates were characterized as CRAB, MDRAB or DTRAB. The prevalence of drug-resistant A. baumannii was >70.0% in South Korea, India and China, while the resistance rate of tigecycline was <5.5%. The MICs of meropenem and meropenem/vaborbactam for drug-resistant A. baumannii were equal (both MIC₅₀ and MIC₉₀ were 32 mg/L, range 0.25-32 mg/L). The overall resistance rate remained high for multiple classes of antibiotics, including penicillins, cephalosporins, carbapenems, quinolones and aminoglycosides (>84.0%, >96.0%, >98.0%, >88.0% and >87.0%, respectively), but not colistin or tigecycline (1.1% and 4.3%, respectively). China showed the lowest susceptibility to tigecycline for drug-resistant A. baumannii isolates compared with other countries. In conclusion, the resistance rate of drug-resistant A. baumannii remains high against multiple classes of antimicrobials. Colistin was the most potent agent, followed by tigecycline. The geographic pattern of tigecycline-resistant A. baumannii varied among countries. Therefore, continuous surveillance of A. baumannii resistance profiles in different regions is required.

The effect of Lactobacillus with prebiotics on KPC-2-producing Klebsiella pneumoniae

Objectives

This study investigated the inhibitory effect of Lactobacillus spp. with prebiotics against Klebsiella pneumoniae carbapenemase-2 (KPC-2)-producing Klebsiella pneumoniae using both in vitro experiments and animal models.

Methods

Thirty-three Lactobacillus spp. strains were confirmed by 16S rDNA sequencing, and four different PFGE genotyped KPC-2-producing K. pneumoniae strains were selected for investigation. In vitro studies, including broth microdilution assays, changes in pH values in lactobacilli cultures with different prebiotics, time-kill tests of Lactobacillus spp. against KPC-2-producing K. pneumoniae and further in vivo Lactobacillus alone or in combination with prebiotics against KPC-2-producing K. pneumoniae in an animal model, were performed.

Results

The lower pH value of the cell-free supernatant was associated with a lower minimal inhibitory percentage of the Lactobacillus strain against KPC-2-producing K. pneumoniae. Furthermore, lactulose/isomalto-oligosaccharide/inulin and fructo-oligosaccharide can enhance the inhibitory effect of all 10⁷ CFU/ml Lactobacillus strains against KPC001. Three Lactobacillus strains (LYC1154, LYC1322, and LYC1511) that could be persistently detected in the stool were tested for their ability to reduce the amount of KPC001 in the feces individually or in combination. A significantly better effect in reducing the amount of KPC001 was observed for the combination of three different Lactobacillus species than for each of them alone. Furthermore, their inhibitory effect was enhanced after adding lactulose or isomalto-oligosaccharide (both p < 0.05).

Conclusion

This study demonstrates the inhibitory effect of probiotic Lactobacillus, including LYC1154, LYC1322, and LYC1511, with prebiotics such as lactulose or isomalto-oligosaccharide against the colonization of KPC-2-producing K. pneumoniae.

An Update of Mobile Colistin Resistance in Non-Fermentative Gram-Negative Bacilli

Colistin, the last resort for multidrug and extensively drug-resistant bacterial infection treatment, was reintroduced after being avoided in clinical settings from the 1970s to the 1990s because of its high toxicity. Colistin is considered a crucial treatment option for Acinetobacter baumannii and Pseudomonas aeruginosa, which are listed as critical priority pathogens for new antibiotics by the World Health Organization. The resistance mechanisms of colistin are considered to be chromosomally encoded, and no horizontal transfer has been reported. Nevertheless, in November 2015, a transmissible resistance mechanism of colistin, called mobile colistin resistance (MCR), was discovered. Up to ten families with MCR and more than 100 variants of Gram-negative bacteria have been reported worldwide. Even though few have been reported from Acinetobacter spp. and Pseudomonas spp., it is important to closely monitor the epidemiology of mcr genes in these pathogens. Therefore, this review focuses on the most recent update on colistin resistance and the epidemiology of mcr genes among non-fermentative Gram-negative bacilli, especially Acinetobacter spp. and P. aeruginosa.