Multidrug-resistant Gram-negative Bacteria Research Articles

Genomic characterization of multi drug resistant ESBL-producing Escherichia coli isolates from patients and patient environments in a teaching hospital in Ghana

BackgroundESBL-producing Escherichia coli pose a growing health risk in community and healthcare settings. We investigated the resistome, virulome, mobilome, and genetic relatedness of multidrug-resistant (MDR) E. coli isolates from patients and their environment in a Ghanaian teaching hospital.Materials and methodsTwenty-three MDR ESBL-producing or carbapenem-resistant E. coli isolates from a collection of MDR Gram-negative bacteria (GNB) from patients and environments were selected for genomic analyses. Whole genome sequencing and bioinformatics tools were used to analyze genomic characteristics and phylogeny.ResultsThe prevalence and incidence of rectal carriage of ESBL E. coli among patients were 13.65% and 11.32% respectively. The β-lactamase genes, blaTEM−1B (10 isolates) and blaCTX−M−15 (12 isolates) were commonly associated with IncFIB plasmid replicons and co-occurred with aminoglycoside, macrolide, and sulfamethoxazole/trimethoprim resistance. Insertion sequences, transposons, and class I integrons were found with blaCTX−M−15. Carriage and environmental isolates carried multiple virulence genes, with terC being the most prevalent in 21 isolates. Seventeen sequence types (STs) were identified, including a novel ST (ST13846). Phylogenetic analysis grouped the isolates into four main clusters, with one outlier. High genetic relatedness was observed between two carriage isolates of ST940 and between a carriage isolate and an environmental isolate of ST648. Isolates with different STs, collected at different times and locations, also showed genetic similarities.ConclusionWe identified ESBL-producing E. coli with diverse genomic characteristics circulating in different hospital directorates. Clonal relatedness was observed among isolates from patients and the environment, as well as between different patients, suggesting transmission within and between sources.

Adult acute leukemia patients with gram-negative bacteria bloodstream infection: Risk factors and outcomes of antibiotic-resistant bacteria.

This study aims to analyze the risk factors for the development of multidrug-resistant (MDR) and carbapenem-resistant (CR) bacteria bloodstream infection (BSI) in a patient with acute leukemia (AL) and the mortality in gram-negative bacteria (GNB) BSI. This is a retrospective study conducted at West China Hospital of Sichuan University, which included patients diagnosed with AL and concomitant GNB BSI from 2016 to 2021. A total of 206 patients with GNB BSI in AL were included. The 30-day mortality rate for all patients was 26.2%, with rates of 25.8% for those with MDR GNB BSI and 59.1% for those with CR GNB BSI. Univariate and multivariate analyses revealed that exposure to quinolones (Odds ratio (OR) = 3.111, 95% confidence interval (95%CI): 1.623-5.964, p = 0.001) within the preceding 30 days was an independent risk factor for MDR GNB BSI, while placement of urinary catheter (OR = 6.311, 95%CI: 2.478-16.073, p< 0.001) and exposure to cephalosporins (OR = 2.340, 95%CI: 1.090-5.025, p = 0.029) and carbapenems (OR = 2.558, 95%CI: 1.190-5.497, p = 0.016) within the preceding 30 days were independently associated with CR GNB BSI. Additionally, CR GNB BSI (OR = 2.960, 95% CI: 1.016-8.624, p = 0.047), relapsed/refractory AL (OR = 3.035, 95% CI: 1.265-7.354, p = 0.013), septic shock (OR = 5.108, 95% CI: 1.794-14.547, p = 0.002), platelets < 30 × 109/L before BSI (OR = 7.785, 95% CI: 2.055-29.492, p = 0.003), and inappropriate empiric antibiotic therapy (OR = 3.140, 95% CI: 1.171-8.417, p = 0.023) were independent risk factors for 30-day mortality in AL patients with GNB BSI. Prior antibiotic exposure was a significant factor in the occurrence of MDR GNB BSI and CR GNB BSI. CR GNB BSI increased the risk of mortality in AL patients with GNB BSI.

Ceftazidime-Avibactam as a Salvage Treatment for Severely Infected Immunosuppressed Children.

Multidrug-resistant Gram-negative bacteria (MDR-GNB) are becoming increasingly common around the world, with carbapenems frequently serving as a last resort but being threatened by the growing incidence of carbapenemase-producing bacteria. Ceftazidime-avibactam (CAZ/AVI) is a potential agent against MDR-GNB but with limited clinical experience, particularly in critically ill immunosuppressed children. This study analyzed the use of CAZ/AVI as salvage treatment in severely infected immunosuppressed children from September 2019 to July 2022. Patients with confirmed GNB infection who received CAZ/AVI were matched with patients who received other antibiotics. Twenty-five critically ill immunosuppressed children treated with CAZ/AVI were included. The majority had hematologic diseases. All patients presented with sepsis in all 30 courses. Septic shock presented in 36.7% of these courses. The primary sites of infection included bloodstream infection (20.0%), skin and skin structure infection (20.0%), intra-abdominal infection (13.3%) and hospital-acquired pneumonia (10.0%). Twelve of the 25 (48.0%) patients had positive microbiological cultures, mainly Pseudomonas aeruginosa and Klebsiella pneumoniae, including 5 carbapenem-resistant GNB-infected cases. Fifteen (50.0%) courses presented clinical improvement. For the initial course of each patient, the clinical response rate of the GNB recovered group was significantly higher than that of the group without GNB recovery (66.7% vs 23.1%, P = 0.047). The 14-day and 30-day mortality rates were 24.0% and 28.0%, respectively, which were significantly correlated with the absence of GNB recovery (P = 0.004 and 0.024, respectively) and hospital-acquired pneumonia as the primary site of infection (P = 0.001 and 0.006, respectively). There was no significant difference in major outcomes between patients who received CAZ/AVI and matched patients who received other antibiotics. CAZ/AVI could be considered a salvage strategy for immunosuppressed children with confirmed GNB infection. Caution should be taken when CAZ/AVI is applied to these patients in the absence of GNB recovery.

Temporal decreases in pathogen colonization and infection among hospitalized neonates following routine skin antisepsis with chlorhexidine gluconate: Botswana 2022 – 2023

Background: Multidrug-resistant Gram-negative bacteria are a major cause of sepsis among hospitalized neonates globally. Aqueous chlorhexidine gluconate (CHG) skin antisepsis has been shown to be safe for use in infants; however, its sustained effectiveness in preventing Gram-negative pathogen colonization, bloodstream infection (BSI), and mortality is unclear. Methods: We conducted a period prevalence survey, with 26 sampling events over 12 months (18 October 2022 – 31 October 2023) at a 33-bed neonatal unit in a tertiary public hospital in Botswana where ESBL-producing Klebsiella pneumoniae and carbapenem-resistant Acinetobacter baumannii are leading causes of BSI. Perirectal and periumbilical skin swabs were collected every two weeks from all inpatients. Swabs were inoculated onto chromogenic media selective and differential for extended-spectrum beta-lactamase producing Enterobacterales (ESBL-E) and Acinetobacter spp. (CHROMagar™ ESBL, Acinetobacter). Colonization status was determined based on culture growth and colony morphology. Contemporaneous data on all-cause mortality and BSI were abstracted from routine surveillance records. Pre- and post-CHG prevalences were compared using a simple Chi-square test. During the surveillance period, an outbreak of K. pneumoniae linked to contaminated multi-use vials was detected, thus BSIs and deaths during the outbreak period (2 February–6 April, 2023) were excluded. In February 2023, the hospital infection prevention and control (IPC) team introduced twice-weekly whole-body cleansing with commercially available 2% aqueous CHG, performed by caregivers and healthcare workers on neonates &gt;24 hours old and weighing ≥1 kg until discharge. Results: There were significant decreases in ESBL-E and Acinetobacter skin and perirectal colonization following the CHG intervention (Table 1; Figure 1). After the CHG intervention, the incidence of Acinetobacter BSIs declined significantly and there was a trend toward a decline in other BSIs and mortality. No adverse events associated with CHG were reported. Conclusions: Twice-weekly CHG application was temporally associated with significant reductions in neonatal ESBL-E and Actinetobacter skin and perirectal colonization and Acinetobacter BSI. This analysis was limited by a short pre-intervention surveillance period and thus may have been influenced by confounders such as seasonality, and intensified IPC efforts following the outbreak. Analysis of the routine CHG use in other settings and over longer surveillance periods are needed to better understand its effectiveness as an IPC strategy in settings where neonatal sepsis incidence is high. Table 1. Colonization prevalence, BSI incidence, and mortality surrounding introduction of CHG skin cleansing in a neonatal unit, 18 October 2022 – 31 October 2023.

Gut colonization with multidrug resistant organisms in the intensive care unit: a systematic review and meta-analysis

BackgroundGut colonization with multidrug-resistant organisms (MDRO) frequently precedes infection among patients in the intensive care unit (ICU), although the dynamics of colonization are not completely understood. We performed a systematic review and meta-analysis of ICU studies which described the cumulative incidence and rates of MDRO gut acquisition.MethodsWe systematically searched PubMed, Embase, and Web of Science for studies published from 2010 to 2023 reporting on gut acquisition of MDRO in the ICU. MDRO were defined as multidrug resistant non-Pseudomonas Gram-negative bacteria (NP-GN), Pseudomonas spp., and vancomycin-resistant Enterococcus (VRE). We included observational studies which obtained perianal or rectal swabs at ICU admission (within 48 h) and at one or more subsequent timepoints. Our primary outcome was the incidence rate of gut acquisition of MDRO, defined as any MDRO newly detected after ICU admission (i.e., not present at baseline) for all patient-time at risk. The study was registered with PROSPERO, CRD42023481569.ResultsOf 482 studies initially identified, 14 studies with 37,305 patients met criteria for inclusion. The pooled incidence of gut acquisition of MDRO during ICU hospitalization was 5% (range: 1–43%) with a pooled incidence rate of 12.2 (95% CI 8.1–18.6) per 1000 patient-days. Median time to acquisition ranged from 4 to 26 days after ICU admission. Results were similar for NP-GN and Pseudomonas spp., with insufficient data to assess VRE. Among six studies which provided sufficient data to perform curve fitting, there was a quasi-linear increase in gut MDRO colonization of 1.41% per day which was stable through 30 days of ICU hospitalization (R2 = 0.50, p < 0.01).ConclusionsAcquisition of gut MDRO was common in the ICU and increases with days spent in ICU through 30 days of follow-up. These data may guide future interventions seeking to prevent gut acquisition of MDRO in the ICU.

Epidemiology, Risk Factors, and Outcomes of Health Care-Associated Infections in the Neonatal Intensive Care Unit: 6-Year Surveillance at a University Hospital in Türkiye

Abstract Objective Health care-associated infections (HAIs) are important causes of morbidity and mortality in neonatal intensive care units (NICUs). This study aimed to evaluate the frequency of HAIs and related factors in the NICU. Methods HAIs detected and monitored by daily active surveillance by the Infection Control Team at Necmettin Erbakan University Faculty of Medicine NICU between January 1, 2017 and December 31, 2022 were evaluated retrospectively. There were a total of 43 incubators in our hospital's NICU (19 secondary level units and 24 tertiary level). Between 2017 and 2022, there was an average of 982 admissions to the NICU per year. Results A total of 5,895 newborns and 74,726 patient days were monitored in the study. The average HAIs rate for all study years was 3.4% and the incidence density was 2.68 per thousand patient days. The highest HAI rate was in newborns with birth weights &lt; 750 g. A total of 201 HAIs were detected in 172 patients. Bloodstream infection (BSI) was the most frequent HAI. The most frequent pathogens were Klebsiella spp. (44.8%), methicillin-resistant coagulase-negative staphylococci (CoNS) (24.4%), and Acinetobacter spp. (11.6%). Note that 88.5% of Enterobacterales were extended-spectrum beta-lactamase producers, and 26% of Klebsiella spp. were carbapenem-resistant. No colistin resistance was detected in Pseudomonas aeruginosa and Acinetobacter spp. Methicillin resistance was detected in 86.5% of CoNS and 50% of Staphylococcus aureus. The vancomycin resistance rate in Enterococcus spp. was 40%. Note that 16.7% of Candida spp. were fluconazole-resistant; no resistance to caspofungin was found. The most common risk factors for development of HAI were prematurity, umbilical catheter use, total parenteral nutrition, and mechanical ventilation. The mortality rate in patients with HAIs was 20.9%. Conclusion HAIs, including those caused by multidrug-resistant Gram-negative bacteria, are an important problem in our hospital, and also globally. Active surveillance should be continued, and changes over the years evaluated. Infection control programs should be executed by determining the risk and mortality factors attributed to infection and their implementation should be closely monitored. These practices will increase success in the fight against HAIs and antimicrobial resistance.

Efficacy of Zoliflodacin, a Spiropyrimidinetrione Antibiotic, Against Gram-Negative Pathogens.

Zoliflodacin is a spiropyrimidinetrione antibiotic that acts by binding to the GyrB part of the DNA gyrase enzyme in bacteria. Its effectiveness for the treatment of Neisseria gonorrhoeae infections has been investigated extensively. Since antibiotic resistance has been reached an alarming rate worldwide, researches on new antimicrobials are considered a priority, especially in the treatment of multidrug-resistant Gram-negative bacteria, such as Klebsiella pneumonia. The aim of this study is to test and compare the effectiveness of zoliflodacin with some traditional antibiotics which are frequently preferred in the treatment of Gram-negative pathogens, primarily K. pneumonia. Additionally, its ability to prevent biofilm formation has also been determined. The minimum inhibitory concentration (MIC) values of zoliflodacin along with levofloxacin, meropenem, gentamicin, ampicillin/sulbactam and ceftazidime/avibactam were evaluated by broth microdilution method against 15 Gram-negative clinical isolates and three standard strains. Also, the synergism potential of zoliflodacin with other antibiotics was evaluated by the checkerboard method against standard strains of K. pneumonia, Pseudomonas aeruginosa, and Acinetobacter baumannii. In addition, the inhibitory effects of zoliflodacin on biofilm formation of standard strains were determined. Zoliflodacin MICs were found to be in the range of 2-64µg/mL, and its combination with meropenem and ampicillin/sulbactam was found to be synergistic, especially against A. baumannii. Zoliflodacin significantly inhibited A. baumannii biofilm at sub-MIC values. These results indicated that zoliflodacin can be considered as an alternative against infections of Gram-negative pathogens, alone or in combination.

Distribution and molecular characterization of carbapenemase-producing gram-negative bacteria in Henan, China

This study aimed to investigate the epidemiological characteristics and trends over time of carbapenemase-producing (e.g., KPC, NDM, VIM, IMP, and OXA-48) Gram-negative bacteria (CPGNB). Non-duplicated multi-drug resistant Gram-negative bacteria (MDRGNB) were collected from the First Affiliated Hospital of Zhengzhou University from April 2019 to February 2023. Species identification of each isolate was performed using the Vitek2 system and confirmed by matrix-assisted laser desorption ionization-time of flight mass spectrometry according to the manufacturer's instructions. PCR detected carbapenem resistance genes in the strains, strains carrying carbapenem resistance genes were categorized as CPGNB strains after validation by carbapenem inactivation assay. A total of 5705 non-repetitive MDRGNB isolates belonging to 78 different species were collected during the study period, of which 1918 CPGNB were validated, with the respiratory tract being the primary source of specimens. Epidemiologic statistics showed a significant predominance of ICU-sourced strains compared to other departments. Klebsiella pneumoniae, Escherichia coli, Acinetobacter baumannii, and Pseudomonas aeruginosa were the significant CPGNB in Henan, and KPC and NDM were the predominant carbapenemases. Carbapenem-resistant infections in Henan Province showed an overall increasing trend, and the carriage of carbapenemase genes by CPGNB has become increasingly prevalent and complicated. The growing prevalence of CPGNB in the post-pandemic era poses a significant challenge to public safety.

Novel functions of o-cymen-5-ol nanoemulsion in reversing colistin resistance in multidrug-resistant Klebsiella pneumoniae infections

Multidrug resistance (MDR) Klebsiella pneumoniae (K. pneumoniae) is a major emerging threat to human health, and leads to very high mortality rate. The effectiveness of colistin, the last resort against MDR Gram-negative bacteria, is significantly compromised due to the widespread presence of plasmid- or chromosome-mediated resistance genes. In this study, o-cymen-5-ol has been found to greatly restore colistin sensitivity in MDR K. pneumoniae. Importantly, this compound does not impact bacterial viability, induce resistance, or cause any noticeable cell toxicity. Various routes disclosed the potential mechanism of o-cymen-5-ol potentiating colistin activity against MDR K. pneumoniae. These include inhibiting the activity of plasmid-mediated mobile colistin resistance gene (mcr-1), accelerating lipopolysaccharide (LPS) − mediated membrane damage, and promoting the ATP-binding cassette (ABC) transporter pathway. To enhance the administration and bioavailability of o-cymen-5-ol, a nanoemulsion has been designed, which significantly improves the loading efficiency and solubility of o-cymen-5-ol, resulting in antimicrobial potentiation of colistin against K. pneumoniae infection. This study has revealed a new understanding of the o-cymen-5-ol nanoemulsion as a means to enhance the effectiveness of colistin against resistant factors. The finding also suggests that o-cymen-5-ol nanoemulsion could be a promising approach in the development of potential treatments for multidrug-resistant Gram-negative bacterial infections.

Colistin: Lights and Shadows of an Older Antibiotic.

The emergence of antimicrobial resistance represents a serious threat to public health and for infections due to multidrug-resistant (MDR) microorganisms, representing one of the most important causes of death worldwide. The renewal of old antimicrobials, such as colistin, has been proposed as a valuable therapeutic alternative to the emergence of the MDR microorganisms. Although colistin is well known to present several adverse toxic effects, its usage in clinical practice has been reconsidered due to its broad spectrum of activity against Gram-negative (GN) bacteria and its important role of "last resort" agent against MDR-GN. Despite the revolutionary perspective of treatment with this old antimicrobial molecule, many questions remain open regarding the emergence of novel phenotypic traits of resistance and the optimal usage of the colistin in clinical practice. In last years, several forward steps have been made in the understanding of the resistance determinants, clinical usage, and pharmacological dosage of this molecule; however, different points regarding the role of colistin in clinical practice and the optimal pharmacokinetic/pharmacodynamic targets are not yet well defined. In this review, we summarize the mode of action, the emerging resistance determinants, and its optimal administration in the treatment of infections that are difficult to treat due to MDR Gram-negative bacteria.

Gram-negative bacterial infections in surgical intensive care unit patients following abdominal surgery: high mortality associated with Stenotrophomonas maltophilia infection

BackgroundStenotrophomonas maltophilia, a multidrug-resistant gram-negative bacteria (GNB), is an emerging nosocomial pathogen. This study assessed the clinical outcomes of GNB infections in surgical intensive care unit (SICU) patients post-abdominal surgery, focusing on the differences between S. maltophilia and other GNBs, including Pseudomonas aeruginosa.MethodsA retrospective study was conducted on SICU patients at Kaohsiung Chang Gung Memorial Hospital from 2010 to 2020, who developed GNB infections following abdominal surgery.ResultsOf 442 patients, 237 had S. maltophilia and 205 had non-S. maltophilia GNB infections (including 81 with P. aeruginosa). The overall mortality rate was 44.5%, and S. maltophilia infection emerged as a significant contributor to the mortality rate in patients with GNB infections. S. maltophilia patients had longer mechanical ventilation and SICU stays, with a 30-day mortality rate of 35.4%, higher than the non-S. maltophilia GNB (22.9%) and P. aeruginosa (21%) groups. In-hospital mortality was also higher in the S. maltophilia group (53.2%) compared to the non-S. maltophilia GNB (34.6%) and P. aeruginosa groups (29.6%). Risk factors for acquiring S. maltophilia included a higher Sequential Organ Failure Assessment score and prior broad-spectrum antibiotics use. Older age, polymicrobial infections, and elevated bilirubin were associated with increased 30-day mortality in S. maltophilia patients.ConclusionS. maltophilia infections in post-abdominal surgery patients are linked to higher mortality than non-S. maltophilia GNB and P. aeruginosa infections, emphasizing the need for early diagnosis and treatment to improve outcomes.

Colistin-resistance genes in Escherichia coli isolated from patients with urinary tract infections.

The incidence of antimicrobial resistance is alarmingly high because it occurs in humans, environment, and animal sectors from a "One Health" viewpoint. The emergence of plasmid-carried mobile colistin-resistance (MCR) genes limits the efficacy of colistin, which is the last-line treatment for multidrug resistance (MDR) against gram-negative infections. The current study aimed to investigate emergence of colistin-resistance (MCR 1-5) genes in E. coli isolated from patients with urinary tract infections (UTIs) in Jordan. E. coli (n = 132) were collected from urine specimens. The E. coli isolated from human UTI patients were examined the resistance to colistin based on the presence of MCR (1-5). All isolates were tested against 20 antimicrobials using the standard disk diffusion method. The broth microdilution technique was used to analyze colistin resistance. In addition, the MCR (1-5) genes were detected using multiplex PCR. Out of the 132 isolates, 1 isolate was colistin-resistant, having a minimum inhibitory concentration of 8 μg/mL and possessing MCR-1. All the E. coli isolates showed high resistance to penicillin (100%), amoxicillin (79.55%), cephalexin (75.76%), nalidixic acid (62.88%), tetracycline (58.33%), or cefepime (53.79). To our knowledge, this is the first report on the presence of plasmid-coded MCR-1 in E. coli from a patient with UTIs in Jordan. This is a problematic finding because colistin is the last-line drug for the treatment of infections caused by MDR gram-negative bacteria. There is a crucial need to robustly utilize antibiotics to control and prevent the emergence and prevalence of colistin-resistance genes.

Mobile Colistin-Resistant Genes mcr-1, mcr-2, and mcr-3 Identified in Diarrheal Pathogens among Infants, Children, and Adults in Bangladesh: Implications for the Future.

Colistin is a last-resort antimicrobial for treating multidrug-resistant Gram-negative bacteria. Phenotypic colistin resistance is highly associated with plasmid-mediated mobile colistin resistance (mcr) genes. mcr-bearing Enterobacteriaceae have been detected in many countries, with the emergence of colistin-resistant pathogens a global concern. This study assessed the distribution of mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5 genes with phenotypic colistin resistance in isolates from diarrheal infants and children in Bangladesh. Bacteria were identified using the API-20E biochemical panel and 16s rDNA gene sequencing. Polymerase chain reactions detected mcr gene variants in the isolates. Their susceptibilities to colistin were determined by agar dilution and E-test by minimal inhibitory concentration (MIC) measurements. Over 31.6% (71/225) of isolates showed colistin resistance according to agar dilution assessment (MIC > 2 μg/mL). Overall, 15.5% of isolates carried mcr genes (7, mcr-1; 17, mcr-2; 13, and mcr-3, with co-occurrence occurring in two isolates). Clinical breakout MIC values (≥4 μg/mL) were associated with 91.3% of mcr-positive isolates. The mcr-positive pathogens included twenty Escherichia spp., five Shigella flexneri, five Citrobacter spp., two Klebsiella pneumoniae, and three Pseudomonas parafulva. The mcr-genes appeared to be significantly associated with phenotypic colistin resistance phenomena (p = 0.000), with 100% colistin-resistant isolates showing MDR phenomena. The age and sex of patients showed no significant association with detected mcr variants. Overall, mcr-associated colistin-resistant bacteria have emerged in Bangladesh, which warrants further research to determine their spread and instigate activities to reduce resistance.

LysJEP8: A promising novel endolysin for combating multidrug-resistant Gram-negative bacteria.

Antimicrobial resistance (AMR) is an escalating global health crisis, driven by the overuse and misuse of antibiotics. Multidrug-resistant Gram-negative bacteria, such as Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae, are particularly concerning due to their high morbidity and mortality rates. In this context, endolysins, derived from bacteriophages, offer a promising alternative to traditional antibiotics. This study introduces LysJEP8, a novel endolysin derived from Escherichia phage JEP8, which exhibits remarkable antimicrobial activity against key Gram-negative members of the ESKAPE group. Comparative assessments highlight LysJEP8's superior performance in reducing bacterial survival rates compared to previously described endolysins, with the most significant impact observed against P. aeruginosa, and notable effects on A. baumannii and K. pneumoniae. The study found that LysJEP8, as predicted by in silico analysis, worked best at lower pH values but lost its effectiveness at salt concentrations close to physiological levels. Importantly, LysJEP8 exhibited remarkable efficacy in the disruption of P. aeruginosa biofilms. This research underscores the potential of LysJEP8 as a valuable candidate for the development of innovative antibacterial agents, particularly against Gram-negative pathogens, and highlights opportunities for further engineering and optimization to address AMR effectively.

Clinical Utility of Blood Culture Identification 2 Panel in Flagged Blood Culture Samples from the Intensive Care Unit of a Tertiary Care Hospital.

The availability of rapid diagnostic platforms for positive blood cultures has accelerated the speed at which the clinical microbiology laboratory can identify the causative organism and facilitate early appropriate antimicrobial therapy. There is a paucity of data regarding the clinical utility of the blood culture identification 2 (BCID2) panel test and its correlation with phenotypic drug susceptibility testing (DST) in flagged blood culture bottles from intensive care units (ICUs) in countries such as India, which have high rates of multidrug-resistant gram-negative bacteria (MDR-GNB). We conducted a retrospective observational study in a tertiary care ICU on 200 patients above 18 years of age in whom a BCID2 test was ordered when blood cultures flagged positive. We found 99% concordance between BCID2 and cultures in the identification of bacteria and yeasts and 96.5% concordance between phenotypic and genotypic DST. Furthermore, BCID2 was available about 1.5 days earlier than conventional ID and DST and played a key role in tailoring antimicrobials in 82.5% of the patients. Polymyxin-based therapy was discontinued earlier after an empiric dose in 138 patients (69%) based on BCID2 reports. In critically ill patients with monomicrobial bacteremia, BCID2 rapidly identifies bacteria and antimicrobial resistance (AMR) genes and is significantly faster than conventional culture and sensitivity testing. Antibiotics were escalated in more than a third of patients and de-escalated in almost a fifth on the same day. We recommend that all ICUs routinely incorporate the test in their antibiotic decision-making process and in antimicrobial stewardship. Vineeth VK, Nambi PS, Gopalakrishnan R, Sethuraman N, Ramanathan Y, Chandran C, et al. Clinical Utility of Blood Culture Identification 2 Panel in Flagged Blood Culture Samples from the Intensive Care Unit of a Tertiary Care Hospital. Indian J Crit Care Med 2024;28(5):461-466.

The use of new antibacterial drugs against infections caused by multidrug-resistant Gram-negative bacteria: an Italian real-world evidence study in a Lombardy hospital.

Infections caused by multidrug-resistant (MDR) bacteria are typically associated with high morbidity and mortality, especially in vulnerable individuals such as patients with prolonged hospitalizations, immunocompromised individuals, and the elderly. This study aimed to provide post-marketing surveillance results concerning the prevalence of antibiotic resistance against Gram-negative bacteria through the collaboration of a multidisciplinary team. Patients involved have been treated with new antibacterial drugs, in particular ceftazidime/avibactam (C/A), meropenem/vaborbactam (M/V), cefiderocol, and ceftolozane/tazobactam (C/T). The most resistant bacterial species were Klebsiella spp., Pseudomonas aeruginosa, and Acinetobacter baumannii. Italian Drug Agency (AIFA) monitoring records for inpatients have been collected and analyzed, assessing the characteristics of the patients involved. Adverse drug reactions (ADRs) and drugs involved have been reported using a descriptive analytical approach. All data have been collected retrospectively from patient's medical records and entered into an electronic case report form (CRF). Among the 104 treated patients, Klebsiella spp. accounted for 50.1% of infections, Pseudomonas aeruginosa for 32.7%, Acinetobacter baumannii for 3%, and other bacterial species for 1.92% configuring polymicrobial infections. Regarding treatment outcomes, healing was achieved in 61 (58.6%) patients, 23 (22.1%) patients died, 8 (7.7%) patients discontinued empirical therapy, and 3 (2.9%) patients were lost to follow-up. Despite the introduction of new antibacterial drugs active against Gram-negative bacteria is improving the clinical scenario, it is crucial that the use of new antibacterial drugs be implemented by appropriate antimicrobial stewardship, surveillance programs, and monitoring efforts to prevent further spread of resistance. This study showed that the new antibiotics have good efficacy against MDR bacteria and cause negligible side effects.

Microbial infections in burn patients.

Polymicrobial infections are the leading causes of complications incurred from injuries that burn patients develop. Such patients admitted to the hospital have a high risk of developing hospital-acquired infections, with longer patient stays leading to increased chances of acquiring such drug-resistant infections. Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Proteus mirabilis are the most common multidrug-resistant (MDR) Gram-negative bacteria identified in burn wound infections (BWIs). BWIs caused by viruses, like Herpes Simplex and Varicella Zoster, and fungi-like Candida spp. appear to occur occasionally. However, the preponderance of infection by opportunistic pathogens is very high in burn patients. Variations in the causative agents of BWIs are due to differences in geographic location and infection control measures. Overall, burn injuries are characterized by elevated serum cytokine levels, systemic immune response, and immunosuppression. Hence, early detection and treatment can accelerate the wound-healing process and reduce the risk of further infections at the site of injury. A multidisciplinary collaboration between burn surgeons and infectious disease specialists is also needed to properly monitor antibiotic resistance in BWI pathogens, help check the super-spread of MDR pathogens, and improve treatment outcomes as a result.

Enhancing the effectiveness of Polymyxin E with a Fisetin Nanoemulsion against a Colistin-resistant Salmonella typhimurium infection

BackgroundPolymyxin E is widely recognized as a last resort for treating multidrug-resistant gram-negative bacteria. Unfortunately, the effectiveness of polymyxin E is significantly reduced when treating life-threatening bacterial infections due to plasmid-mediated polymyxin E resistance. The synergistic effect of applying a polymyxin E adjuvant is a promising strategy for overcoming the growing threat of antibiotic-resistant pathogens. PurposeTo evaluate the synergistic effect of fisetin and polymyxin E on S. typhimurium infections in vivo and further elucidate the underlying mechanism of this effect. MethodsThe effect of combining fisetin and polymyxin E to treat mobilized colistin resistance-1-positive (MCR-1-positive) gram-negative bacteria in vitro was examined using various methods, such as checkerboard assays, growth curves and time‒kill curves. To elucidate the mechanism by which fisetin affects MCR-1, we employed ultraviolet (UV) absorption spectroscopy, thin layer chromatography (TLC), and western blot analysis to investigate its effect at the protein level. Subsequently, molecular dynamics simulations (MDS) and metabolomics analysis were utilized to determine the site of interaction between fisetin and MCR-1 as well as the potential pathways and mechanisms involved. A new nanoemulsion of fisetin was produced using high-pressure homogenization, and its stability was tested. Finally, two animal models of S. typhimurium HYM2 infection were established to evaluate the synergistic effect of polymyxin E and fisetin in vivo. ResultsOur study revealed that fisetin exhibited a synergistic effect when combined with polymyxin E against MCR-1-positive S. typhimurium. The TLC results demonstrated that fisetin could inhibit the phosphoethanolamine (PEA) transfer of the MCR-1 protein, thereby restoring the activity of polymyxin E in strains against MCR-1. The MDS analysis indicated robust and immediate binding between fisetin and the MCR-1 protein, with both hydrophobic and polar effects playing significant roles in determining the binding energy of the former. Metabolomic studies demonstrated that the addition of fisetin significantly modulated bacterial metabolites. Moreover, it effectively inhibited the activity of ABC transporters in bacteria, thereby mitigating bacterial drug resistance and enhancing the therapeutic efficacy of polymyxin E. Furthermore, in mouse and chick models of infection, intragastric administration of the fisetin nanoemulsion together with polymyxin E resulted in significant therapeutic benefits, including increased survival rates, reduced bacterial colonization, and decreased levels of inflammatory factors. ConclusionFisetin, an MCR-1 inhibitor and a promising synergistic partner of polymyxin E, has significant potential for clinical application in the treatment of S. typhimurium infections, particularly those resulting extensively from drug-resistant MCR-1-positive strains.

Investigation of colistin utilization in the treatment of multidrug-resistant gram-negative nosocomial bloodstream ınfections in children and literature review.

This retrospective study aimed to assess the effectiveness and safety of colistin used in combination therapy for treating nosocomial bloodstream infections caused by multi-drug resistant gram-negative pathogens in pediatric patients. Patients aged between 1month and 18years consecutively hospitalized with healthcare-associated bloodstream infections necessitating the administration of intravenous colistin at Dr. Sami Ulus Training and Research Hospital between January 2015 and January 2020 were included in the study. Patient-specific detailed clinical information, prognoses, and laboratory findings on days 1, 3, and 7 of colistin treatment were obtained from medical records. The study included 45 pediatric patients receiving intravenous colistin; 26 (57.8%) were male and 19 (42.2%) were female, with a median age of 18months. While the clinical response was observed at 82.2% and microbiological response at 91.1% with colistin treatment, two patients (4.4%) discontinued treatment due to side effects without assessing treatment response. The most common adverse effect associated with the use of colistin was nephrotoxicity, which occurred in eight patients (17.8%). Among these patients, only one had pre-existing chronic kidney failure. Conclusion: Colistin used in combination therapy may be effective and safe for treating nosocomial infections caused by multi-drug resistant gram-negative bacteria in pediatric patients, who often have high mortality rates and limited treatment options. What is Known: • Colistin is an antibacterial agent used in the treatment of infections caused by multidrug-resistant Gram-negative bacteria (MDR-GNB) and is associated with significant adverse effects such as nephrotoxicity. • The increasing prevalence of hospital-acquired infections has led to the expanded use of colistin in clinical practice. What is New: • The study demonstrates a high clinical and microbiological response rate to combination therapy with colistin in the treatment of infections caused by MDR-GNB. • The study highlights the importance of monitoring nephrotoxicity in pediatric patients receiving colistin, showing that these effects can be reversible after treatment cessation.

Piceatannol: a renaissance in antibacterial innovation unveiling synergistic potency and virulence disruption against serious pathogens.

In the relentless battle against multi-drug resistant Gram-negative bacteria, piceatannol emerges as a beacon of hope, showcasing unparalleled antibacterial efficacy and a unique ability to disrupt virulence factors. Our study illuminates the multifaceted prowess of piceatannol against prominent pathogens-Proteus mirabilis, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae. Notably, piceatannol demonstrated a remarkable ability to inhibit biofilm formation, reduce bacterial mobility, and diminish extracellular enzyme synthesis.Mechanistic insights into piceatannol's activity unraveled its impact on membrane potential, proton motive force, and ATP production. Furthermore, our study delved into piceatannol's anti-quorum sensing (QS) activity, showcasing its potential to downregulate QS-encoding genes and affirming its affinity to critical QS receptors through molecular docking. Crucially, piceatannol exhibited a low propensity for resistance development, positioning it as a promising candidate for combating antibiotic-resistant strains. Its mild effect on red blood cells (RBCs) suggests safety even at higher concentrations, reinforcing its potential translational value. In an in vivo setting, piceatannol demonstrated protective capabilities, significantly reducing pathogenesis in mice infected with P. aeruginosa and P. mirabilis. This comprehensive analysis positions piceatannol as a renaissance in antibacterial innovation, offering a versatile and effective strategy to confront the evolving challenges posed by resilient Gram-negative pathogens.