Common Gram-negative Pathogens Research Articles

Distribution of virulence genes and antimicrobial resistance of Escherichia coli isolated from hospitalized neonates: A multi-center study across China

BackgroundEscherichia coli is the most common gram-negative pathogen to cause neonatal infections. Contemporary virulence characterization and antimicrobial resistance (AMR) data of neonatal E. coli isolates in China are limited. MethodsA total of 159 E. coli strains isolated from neonates were collected and classified into invasive and non-invasive infection groups, according to their site of origin. The presence of virulence genes was determined using polymerase chain reaction (PCR). All the strains were subjected to antimicrobial susceptibility testing using the broth dilution method. ResultsThe top three virulence genes with the highest detection rates were fimH (90.6 %), iutA (88.7 %), and kspMT II (88.1 %). The prevalences of fyuA (p = 0.023), kpsMT K1 (p = 0.019), ibeA (p < 0.001), and iroN (p = 0.027) were significantly higher in the invasive infection group than in the non-invasive infection group. Resistance to ceftazixime, sulfamethoxazole/trimethoprim, and ciprofloxacin was 75.5 %, 65.4 %, and 48.4 %, respectively. Lower rates of resistance to ceftazidime (p = 0.022), cefepime (p = 0.005), ticarcillin/clavulanic acid (p = 0.020) and aztreonam (p = 0.001) were observed in the invasive infection group compared to the non-invasive infection group. The number of virulence genes carried by E. coli was positively correlated with the number of antibiotics to which the isolates were resistant (r = 0.71, p = 0.016), and a specific virulence gene was associated with resistance to various species of antibiotics. ConclusionsNeonatal E. coli isolates carried multiple virulence genes and were highly resistant to antibiotics. Further studies are needed to understand the molecular mechanisms underlying the association between virulence and AMR.

Clinical and Microbiological Profile of Gram-Negative Infections in Critically Ill Diabetic Patients.

Background and aim Type 2 diabetes mellitus (T2DM) is associated with several infections due to hyperglycemia and impaired immunity. This study aims to analyze the clinical and microbiological profile of critically ill T2DM patients with sepsis due to gram-negative bacteria (GNB). Materials and methods A prospective cross-sectional observational study was conducted at Dr. D. Y. Patil Medical College, Hospital & Research Centre, Pune, India, between December 2023 and May 2024, after ethics committee approval. A total of 100 patients (50 T2DM cases and 50 nondiabetic controls), diagnosed with sepsis due to GNB and admitted to the medical ICU, were included in the study. The clinical profile and laboratory investigations of these patients were studied. Cultures were obtained from peripheral/central venous samples, tracheal secretions, and urine samples. Cultures from other specimens, such as ascitic fluid, cerebrospinal fluid, and pus from skin and soft tissue infections, were also obtained. The statistical tests that were applied were two-tailed with a 95% CI, and a p-value of less than 0.05 was considered statistically significant. Results The mean age of critically ill T2DM cases was 60.52 ± 12.88 years. Of the 50 T2DM cases, 28 were males and 22 were females. The most common infection in critically ill T2DM patients was bloodstream infection (n = 21), followed by bronchopneumonia (n = 16) and urinary tract infections (n = 10). Escherichia coli (n = 15) and Klebsiella pneumoniae (n = 15) were the most common gram-negative pathogens isolated. The most common GNB isolated from the blood cultures of critically ill T2DM patients was Acinetobacter spp. (n = 6). The death rate was significantly higher in T2DM patients with GNB sepsis as compared to nondiabetic controls. Conclusion GNBs like E. coli, K. pneumoniae, and Acinetobacter spp. are commonly found in critically ill T2DM patients with sepsis. Bloodstream infection was the most common site of infection in critically ill T2DM cases. Acinetobacter spp. was the most common isolate found in the blood cultures of critically ill T2DM patients. It is important to identify the site of sepsis, isolate the organism, and treat it with appropriate antibiotics promptly in critically ill T2DM patients to improve the outcomes of these patients.

Declining Trend in Antimicrobial Sensitivity in Respiratory Tract Bacterial Pathogens against Commonly Used Drugs at a Tertiary Care Hospital.

Antimicrobial resistance (AMR) is a major health issue. To determine trends in bacterial organisms in respiratory tract infections (RTIs) and their antibiotic sensitivity at a tertiary care center in India, we performed this study. Successive samples received from January 2017 to December 2021 from the respiratory tract (sputum, endotracheal secretion, and bronchoalveolar lavage) from intensive care units and medical inpatients were processed for bacterial growth. The identification of isolates and antibiotic sensitivity patterns was performed using an automated VITEK-2 system. Descriptive statistics are reported. We received 7,204 respiratory samples. Significant bacterial growth was in 3,000 (41.6%), and 2,992 (41.5%) were gram-negative. Klebsiella pneumoniae was the most prevalent, followed by Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli, and Enterobacter aerogenes. Increasing secular trends were observed for Klebsiella and Pseudomonas and declining trends for Acinetobacter and Escherichia (p < 0.05). Antimicrobial sensitivity patterns showed that Klebsiella, Pseudomonas, Acinetobacter, E. coli, and Enterobacter had a high sensitivity with colistin and polymyxin (99-100%). Moderate sensitivity was observed with carbapenems (Acinetobacter: 47.5%, Enterobacter: 62.0%, Escherichia: 76.5%, Klebsiella: 72.3%, Pseudomonas: 66.7%) and tigecycline (Acinetobacter: 50.4%, Enterobacter: 68.0%, Escherichia: 81.1%, Klebsiella: 66.6%, Pseudomonas: 0%). Aminoglycosides had <50% sensitivity for various organisms, and <25% sensitivity was observed with third-generation cephalosporins and quinolones. Trend analysis showed persistent sensitivity of various pathogenic bacteria to colistin and polymyxin and declining pharmacological sensitivity in Acinetobacter (carbapenems and tigecycline), Escherichia (carbapenems, quinolones, and tigecycline), Klebsiella (carbapenems, quinolones, aminoglycosides, and tigecycline), and Pseudomonas (carbapenems and aminoglycosides) species (p < 0.05). Common respiratory tract gram-negative bacterial pathogens at a tertiary care hospital are K. pneumoniae, P. aeruginosa, A. baumannii, and E. coli. All these bacteria demonstrate high sensitivity only with colistin and polymyxin. Significant AMR is observed to carbapenems, tigecycline, aminoglycosides, and third-generation cephalosporins. Secular trends show declining antimicrobial sensitivity among various bacterial pathogens.

System analysis of the ecological distribution of bacteriophages in hospital wastewater

Phage therapy is one of the most important tools for the treatment of infections with multi-drug resistant bacteria. Such phages are usually isolated from hospital effluents, however, no systematic study on the distribution of phages in hospital effluents has been conducted so far. The aim of this study was to isolate the corresponding phages of common pathogenic bacteria isolated in the clinic as hosts, so as to assess the ecological distribution of phages in hospital wastewater and to provide a reference for the isolation and application of phages of drug-resistant bacteria in the clinic. A cross-sectional study design was used in this study. The 125 pathogenic bacteria (belonging to 16 different strains) isolated from the clinical microbiology laboratory of Qilu Hospital of Shandong University from May to June 2023 were selected as the target strains, and the phages corresponding to these strains were isolated and purified from the hospital wastewater by using the double-layer plate sandwich method. At the same time, the distribution of pathogenic bacteria in the same batch of wastewater was analyzed with the help of mNGS sequencing technology, so as to preliminarily investigate the abundance correspondence between pathogenic bacteria and phages in wastewater. The results showed that a total of 56 phage strains were isolated from 125 clinical pathogens as hosts, corresponding to six pathogens, including Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia. All six pathogenic bacteria contained strains with different degrees of drug resistance, with a higher percentage of multi-drug resistant strains in A. baumannii, Escherichia coli and P. aeruginosa. The phage acquisition rates of these six pathogens were, in descending order, Escherichia coli (80%), Stenotrophomonas maltophilia (75%), Pseudomonas aeruginosa (70%), Klebsiella pneumoniae (66.67%), Acinetobacter baumannii (36.36%) and Staphylococcus aureus (12.5%). Preliminary mNGS sequencing results showed that the pathogenic bacteria with higher abundance in the batch of effluent were Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, Acinetobacter baumannii, Klebsiella aerogenes, Klebsiella michiganensis and Pseudomonas aeruginosa. In conclusion, phages of most common clinical Gram-negative pathogens were isolated from hospital wastewater with high isolation rates; however, phages of Gram-positive pathogens were isolated at lower rates, and only phages corresponding to Staphylococcus aureus were isolated in this study. The corresponding mNGS sequencing results showed that the distribution of Gram-negative pathogens in sewage may had a positive correlation with the ecological distribution of phages.

Epidemiology and drug resistance analysis of bloodstream infections in an intensive care unit from a children’s medical center in Eastern China for six consecutive years

BackgroundChildren in the intensive care unit (ICU) who suffer from severe basic diseases and low immunity are usually in critical condition. It is crucial to assist clinicians in selecting the appropriate empirical antibiotic therapies for clinical infection control.MethodsWe retrospectively analyzed data from 281 children with bloodstream infection (BSI). Comparisons of basic data, pathogenic information, and drug resistance of the main bacteria were conducted.ResultsWe detected 328 strains, including Gram-positive bacteria (223, 68%), mainly coagulase-negative Staphylococci (CoNS); Gram-negative bacteria (91, 27.7%); and fungi (14, 4.3%). The results of the binary logistic regression analysis showed that the main basic disease was an independent risk factor for death. Compared with Escherichia coli, Klebsiella pneumoniae exhibited a higher proportion of extended-spectrum β-lactamases (ESBLs), and its resistance to some β-lactamides and quinolones antibiotics were lower. Twenty-seven isolates of multidrug-resistant (MDR) bacteria were detected, of which carbapenem-resistant Acinetobacter baumannii (CRAB) accounted for the highest proportion (13, 48.2%).ConclusionsCoNS was the principal pathogen causing BSI in children in the ICU of children, and Escherichia coli was the most common Gram-negative pathogen. The main basic disease was an independent risk factor for death. It is necessary to continuously monitor patients with positive blood cultures, pay special attention to detected MDR bacteria, and strengthen the management of antibiotics and prevention and control of nosocomial infections.

Rapid identification of bacterial isolates using microfluidic adaptive channels and multiplexed fluorescence microscopy.

We demonstrate the rapid capture, enrichment, and identification of bacterial pathogens using Adaptive Channel Bacterial Capture (ACBC) devices. Using controlled tuning of device backpressure in polydimethylsiloxane (PDMS) devices, we enable the controlled formation of capture regions capable of trapping bacteria from low cell density samples with near 100% capture efficiency. The technical demands to prepare such devices are much lower compared to conventional methods for bacterial trapping and can be achieved with simple benchtop fabrication methods. We demonstrate the capture and identification of seven species of bacteria with bacterial concentrations lower than 1000 cells per mL, including common Gram-negative and Gram-positive pathogens such as Escherichia coli and Staphylococcus aureus. We further demonstrate that species identification of the trapped bacteria can be undertaken in the order of one-hour using multiplexed 16S rRNA-FISH with identification accuracies of 70-98% with unsupervised classification methods across 7 species of bacteria. Finally, by using the bacterial capture capabilities of the ACBC chip with an ultra-rapid antimicrobial susceptibility testing method employing fluorescence imaging and convolutional neural network (CNN) classification, we demonstrate that we can use the ACBC chip as an imaging flow cytometer that can predict the antibiotic susceptibility of E. coli cells after identification.

Trifluoroacetic acid-mediated synthesis of xanthene constructs and their extensive anti-tuberculosis evaluation.

A diverse range of 9-substituted 1,8-dioxohexahydroxanthenes was conceptualized and synthesized through a TFA-mediated approach in near quantitative yields without the use of column chromatography. From a series of 25 compounds, we found that compounds 14c and 14r exhibited promising anti-tuberculosis potential against avirulent and virulent strains of Mycobacterium tuberculosis with a Minimal Inhibitory Concentration (MIC) of 8 μg ml-1, achieving 99% bactericidal activity at the same concentration. This series of compounds was found to be inactive against common Gram-positive and Gram-negative pathogens, indicating that the activity is mycobacteria-specific. Since the strategies for treating tuberculosis employ a combinatorial therapy, we tested and observed that the two lead compounds displayed synergistic behavior with known anti-TB drugs (ATDs) and a significant (16-32 fold) decrease in MIC values of both leads was observed in combination with either RIF or INH. Interestingly the lead molecule 14c displayed only time-dependent kill kinetics and sterilized the whole culture of Mycobacterium tuberculosis H37Rv in just 48 hours.

Susceptibility of Gram-negative isolates collected in South Korea to imipenem/relebactam and comparator agents-SMART 2018-21.

To evaluate the in vitro susceptibility of recent Gram-negative pathogens collected in South Korean medical centres to imipenem/relebactam and comparator agents. From 2018 to 2021, six hospitals in South Korea each collected up to 250 consecutive, aerobic or facultative Gram-negative pathogens per year from patients with bloodstream, intra-abdominal, lower respiratory tract and urinary tract infections. MICs were determined using CLSI broth microdilution and interpreted by 2023 CLSI breakpoints. Most isolates that were imipenem/relebactam, imipenem or ceftolozane/tazobactam non-susceptible were screened for β-lactamase genes by PCR or WGS. Of all non-Morganellaceae Enterobacterales (NME) isolates (n = 4100), 98.8% were imipenem/relebactam susceptible. Most NME were also susceptible to imipenem alone (94.7%) and meropenem (97.3%); percent susceptible values for non-carbapenem β-lactam comparators were lower (68%-80%). Imipenem/relebactam retained activity against 96.4%, 70.8% and 70.6% of MDR, difficult-to-treat resistant (DTR) and meropenem-non-susceptible NME, respectively, and inhibited 93.1% of KPC-carrying and 95.5% of ESBL-carrying NME. Of imipenem/relebactam-resistant NME, 21/25 (84.0%) carried an MBL or an OXA-48-like carbapenemase. Of all Pseudomonas aeruginosa isolates (n = 738), 82.8% were imipenem/relebactam susceptible; percent susceptible values for all β-lactam comparators, including carbapenems (imipenem, meropenem) were 61.5%-74.7%. Less than 20% of MDR and DTR isolates, and 41% of meropenem-non-susceptible P. aeruginosa isolates were imipenem/relebactam susceptible. Of imipenem/relebactam-resistant P. aeruginosa isolates, 61.6% carried an MBL and 37.0% did not possess any acquired β-lactamase genes. Based on in vitro data, imipenem/relebactam, if licensed in South Korea, may be a viable treatment option for many hospitalized patients infected with common Gram-negative pathogens including NME exhibiting MDR, DTR and carbapenem resistance and many β-lactam-resistant phenotypes of P. aeruginosa.

Effect of Low Copper Doping on the Optical, Cytocompatible, Antibacterial, and SARS-CoV-2 Trapping Properties of Calcium Phosphate Glasses.

Calcium phosphate glasses (CPGs) are acquiring great importance in the biomedical field because of their thermomechanical and bioresorbable properties. In this study, optically transparent copper (1 mol %)-doped calcium phosphate glasses (CPGs_Cu) were prepared through the melt-quenching method, and their biocompatibility and antibacterial and antiviral properties were evaluated and compared with undoped CPGs. Biocompatibility was evaluated on murine fibroblast NIH-3T3 cells as a preliminary study of cytocompatibility. The in vitro tests were performed through indirect and direct cytotoxicity analyses by MTT and Alamar Blue assays and supported by electron microscopy observations. Microbiological analyses were performed against the most common Gram-negative and Gram-positive pathogens that cause nosocomial infections: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and the methicillin-resistant Staphylococcus aureus strain. In addition, the bioglass samples were exposed to SARS-CoV-2 to assess their effects on viral survival. The obtained results assessed the biocompatibility of both bioglass types and their ability to reduce the viral load and trap the virus. In addition, Cu2+-doped bioglass was found to be antibacterial despite its low content (1 mol %) of copper, making this a promising candidate material for biomedical applications, e.g., surgery probes, drug delivery, and photodynamic therapy.

Susceptibility of gram-negative isolates collected in Taiwan to imipenem/relebactam and comparator agents – SMART 2018–2021

Imipenem/relebactam (IMR) was approved for patient use in Taiwan in 2023. We evaluated the invitro susceptibility of recent Gram-negative pathogens collected in Taiwan hospitals to IMR and comparators with a focus on carbapenem-resistant and KPC-carrying non-Morganellaceae Enterobacterales (NME), and carbapenem-resistant Pseudomonas aeruginosa (CRPA). From 2018 to 2021, eight hospitals in Taiwan each collected up to 250 consecutive, aerobic or facultative, Gram-negative pathogens per year from patients with bloodstream, intraabdominal, lower respiratory tract, and urinary tract infections. MICs were determined using Clinical Laboratory Standards Institute (CLSI) broth microdilution. Most isolates that were IMR-, imipenem-, or ceftolozane/tazobactam-nonsusceptible were screened for β-lactamase genes by PCR or whole-genome sequencing. Ninety-eight percent of NME (n=5063) and 94% of P. aeruginosa (n=1518) isolates were IMR-susceptible. Percent susceptible values for non-carbapenem β-lactam comparators, including piperacillin/tazobactam, were 68-79% for NME isolates, while percent susceptible values for all β-lactam comparators, including meropenem, were 73-81% for P. aeruginosa. IMR retained activity against 93% of multidrug-resistant (MDR) NME and 70% of MDR P. aeruginosa. Sixty-five percent of carbapenem-resistant NME and 81% of KPC-positive NME (n=80) were IMR-susceptible. IMR inhibited 70% of CRPA (n=287). Fifty percent of IMR-nonsusceptible NME tested for β-lactamase carriage had an MBL or OXA-48-like enzyme, whereas most (95%) IMR-nonsusceptible P. aeruginosa examined did not carry acquired β-lactamase genes. Based on our invitro data, IMR may be a useful option for the treatment of hospitalized patients in Taiwan with infections caused by common Gram-negative pathogens, including carbapenem-resistant NME, KPC-positive NME, and CRPA.

Sensitive and Direct Analysis of Pseudomonas aeruginosa through Self-Primer-Assisted Chain Extension and CRISPR-Cas12a-Based Color Reaction.

Pseudomonas aeruginosa (P. aeruginosa) is a common opportunistic Gram-negative pathogen that may cause infections to immunocompromised patients. However, sensitive and reliable analysis of P. aeruginosa remains a huge challenge. In this method, target recognition assists the formation of a self-primer and initiates single-stranded chain production. The produced single-stranded DNA chain is identified by CRISPR-Cas12a, and consequently, the trans-cleavage activity of the Cas12a enzyme is activated to parallelly digest Ag+ aptamer sequences that are chelated with silver ions (Ag+). The released Ag+ reacted with 3,3',5,5'-tetramethylbenzidine (TMB) for coloring. Compared with the traditional color developing strategies, which mainly rely on the DNA hybridization, the color developing strategy in this approach exhibits a higher efficiency due to the robust trans-cleavage activity of the Cas12a enzyme. Consequently, the method shows a low limit of detection of a wide detection of 5 orders of magnitudes and a low limit of detection of 21 cfu/mL, holding a promising prospect in early diagnosis of infections. Herein, we develop a sensitive and reliable method for direct and colorimetric detection of P. aeruginosa by integrating self-primer-assisted chain production and CRISPR-Cas12a-based color reaction and believe that the established approach will facilitate the development of bacteria-analyzing sensors.

Inhibitory effect of resveratrol on swimming motility and adhesion ability against Salmonella enterica serovar Typhimurium infection

Salmonella enterica serovar Typhimurium (S. typhimurium) is a common Gram-negative foodborne pathogen that threatens public health and hinders the development of livestock industry. Resveratrol, an important component in grape fruits and seeds, has been shown to possess multiple biological activities, but its potential effects on S. typhimurium-mediated virulence have been rarely reported. In this study, we investigated the effect of resveratrol on S. typhimurium flagella -mediated virulence. The results showed that resveratrol significantly reduced the transcription of flagella genes and swimming motility of S. typhimurium, and also inhibited the transcription of T3SS-related virulence genes with varying degrees inhibiting bacterial growth. Simultaneously, resveratrol significantly reduced the adhesion of S. typhimurium to HeLa cells. Unfortunately, resveratrol does not improve the survival rate of S. typhimurium-infected mice, but it reduces the bacterial load in the liver and spleen of infected mice, and it also has a certain degree of anti-inflammatory activity. In summary, these results indicated that resveratrol has the potential to be developed as an alternative drug or antibacterial agent to prevent Salmonella infection.

P20 Rapid 15 min test to identify the three most common Gram-negative uropathogens in urinary tract infections

Abstract Background Every year, 6.2 million cases of urinary tract infection (UTI) are reported in England and Wales and have the second highest antibiotic prescription rate. The absence of fast and sensitive diagnostic tests has increased empirical antibiotic use and has contributed to the rise of antibiotic-resistant infections. To address this challenge, we have developed NANOPLEX™: a rapid 15 min test that uses glycan-functionalized-latex nanoparticles, microscopy and image-analysis software to identify and enumerate samples with bacteria. In this work, we show that NANOPLEX™ can correctly identify the three most common uropathogens using lab reference strains, clinical isolates and clinical urine samples. Materials and Methods The NANOPLEX™ assay was performed as per Vendeville et al. 2021.1 ACS Biomater 2022; 8, 1:242-252. Clinical isolates of Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis were obtained from an NHS clinical microbiology lab waste stream. N=30 isolates (per species) were tested via single-blind study protocols at concentrations of 10³–108 cfu/mL and compared with microbial culture to define performance metrics (sensitivity, specificity, PPV, NPV and accuracy) of each probe. Results A total of 90 isolates were tested against their target probes and demonstrated &amp;gt;90% accuracy (sensitivity 88%–90%, specificity 94%–98%, PPV 93%–98%, NPV 88%–90%, accuracy 91%–94%) for all probe-bacteria combinations at clinically significant concentrations (105 cfu/mL). Conclusions NANOPLEX™ was able to successfully detect the top three common Gram-negative pathogens in UTI at clinically relevant concentrations. A compact hardware and single-use cartridge system is under development to enable urologists to conduct rapid and accurate UTI testing in point-of-care environments. Larger clinical studies are planned to clinically validate these results.

Immunometabolic control by Klebsiella pneumoniae.

Klebsiella pneumoniae is a common Gram-negative pathogen associated with community-acquired and healthcare-associated infections. Its ability to acquire genetic elements resulted in its rapid development of resistance to virtually all antimicrobial agents. Once infection is established, K. pneumoniae is able to evade the host immune response and perhaps more importantly, undergo metabolic rewiring to optimize its ability to maintain infection. K. pneumoniae lipopolysaccharide and capsular polysaccharide are central factors in the induction and evasion of immune clearance. Less well understood is the importance of immunometabolism, the intersection between cellular metabolism and immune function, in the host response to K. pneumoniae infection. Bacterial metabolism itself is perceived as a metabolic stress to the host, altering the microenvironment at the site of infection. In this review, we will discuss the metabolic responses induced by K. pneumoniae, particularly in response to stimulation with the metabolically active bacteria versus pathogen-associated molecular patterns alone, and their implications in shaping the nature of the immune response and the infection outcome. A better understanding of the immunometabolic response to K. pneumoniae may help identify new targets for therapeutic intervention in the treatment of multidrug-resistant bacterial infections.

Trends in antimicrobial susceptibility patterns of bacterial isolates in Lahore, Pakistan

BackgroundAntimicrobial resistance (AMR) has provoked a global health issue. Antimicrobial stewardship programs should be implemented to overcome this issue. The aim of this study was to determine the sensitivity patterns of the WHO Access, Watch, Reserve (AWaRe) group of antibiotics that assists in the selection of appropriate empiric antibiotic therapies.MethodA descriptive, cross-sectional study was conducted for 6 months, in which 422 culture sensitivity sample reports from the Ghurki Trust Teaching Hospital’s laboratory were obtained through a convenience sampling technique, and the sensitivity patterns of nine offending bacteria to the WHO AWaRe group antibiotics were determined. Descriptive statistics and differences in frequency distribution among the categorical variables were obtained using the Statistical Package for Social Sciences (SPSS) software, version 21.ResultsAmong 422 culture sensitivity sample reports, Escherichia coli (16.1%) was the most common Gram-negative pathogen. Acinetobacter, E. coli, Klebsiella, and Pseudomonas showed 100% sensitivity to polymyxin-b and colistin. Proteus showed the highest sensitivity to meropenem (90%), Staphylococcus aureus showed a 98% sensitivity to linezolid, Staphylococcus epidermidis was 100% sensitive to vancomycin and linezolid, and Streptococcus showed the highest sensitivity to penicillin (100%) and vancomycin (94.7%). Polymyxin b and colistin were found to be the most effective antibiotics against Gram-negative bacteria (100%). Gram-positive bacteria were highly sensitive to linezolid (99.4%), vancomycin (98.2%), chloramphenicol (89.5%), and tigecycline (82.6%).ConclusionCulture sensitivity reports help to rationalize the empirical use of antibiotics in clinical practice in addressing the challenge of antimicrobial resistance. This study showed that polymyxin-b and colistin were the most effective antibiotics against Gram-negative isolates and that Gram-positive bacteria were highly susceptible to linezolid. Updated antibiograms should be used by clinicians to evaluate bacterial susceptibility patterns and rationalize antibiotic empiric therapy.

Sublethal Exposure to Common Benzalkonium Chloride Leads to Antimicrobial Tolerance and Antibiotic Cross-Resistance in Commensal and Opportunistic Bacterial Species

The production and consumer use of disinfectants has substantially increased during the COVID-19 pandemic. Benzalkonium chloride (BAC) is a mixture of alkyl benzyl dimethyl ammonium chloride compounds and is the most common active ingredient in surface cleaning and disinfecting products. Accordingly, BAC compounds are routinely in contact with microorganisms in indoor environments, which may contribute to the development of antimicrobial tolerance and cross-resistance. To investigate the impact of BAC exposure on commensal and opportunistic bacteria of public health importance, we exposed Staphylococcus epidermidis, Corynebacterium xerosis, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa to a standard BAC mixture (BAC12–14), as well as purified BAC16. Minimum inhibitory concentrations (MICs) and antibiotic susceptibilities were determined before and after repeated exposure to sublethal BAC concentrations. MICs for Gram-negative bacteria were significantly higher than Gram-positive bacteria. Additionally, BAC12–14 MICs were significantly higher for opportunistic pathogens and BAC-tolerance was associated with antibiotic cross-resistance. These results suggest that common Gram-negative opportunistic pathogens are less sensitive to BAC-inhibition than commensal species and may preferentially develop antimicrobial tolerance upon repeated or prolonged exposure to BAC12–14. Reevaluating the formulation and concentration of BAC-containing products in efforts to limit the development of antimicrobial tolerance and antibiotic co-resistance is warranted.

Incidence of infant Gram-negative invasive bacterial infections in England, 2011–2019: an observational study using population-wide surveillance data

ObjectiveInvasive bacterial infections account for an estimated 15% of infant deaths worldwide. We aimed to estimate the incidence and trends in invasive bacterial infections in infants caused by Gram-negative pathogens...

Effect of appropriate empirical antimicrobial therapy on mortality of patients with Gram-negative bloodstream infections: a retrospective cohort study

BackgroundLittle evidence exists regarding the prevalence of pathogens in bloodstream infections (BSIs), the mortality risk, and the benefit of combination therapy over monotherapy. This study aims to describe patterns of empiric antimicrobial therapy, and the epidemiology of Gram-negative pathogens, and to investigate the effect of appropriate therapy and appropriate combination therapy on the mortality of patients with BSIs.MethodsThis was a retrospective cohort study including all patients with BSIs of Gram-negative pathogens from January 2017 to December 2022 in a Chinese general hospital. The in-hospital mortality was compared between appropriate and inappropriate therapy, and between monotherapy and combination therapy for patients receiving appropriate therapy. We used Cox regression analysis to identify factors independently associated with in-hospital mortality.ResultsWe included 205 patients in the study, of whom 147 (71.71%) patients received appropriate therapy compared with 58 (28.29%) who received inappropriate therapy. The most common Gram-negative pathogen was Escherichia coli (37.56%). 131 (63.90%) patients received monotherapy and 74 (36.10%) patients received combination therapy. The in-hospital mortality was significantly lower in patients administered appropriate therapy than inappropriate therapy (16.33% vs. 48.28%, p = 0.004); adjusted hazard ratio [HR] 0.55 [95% CI 0.35–0.84], p = 0.006). In-hospital mortality was also not different in combination therapy and monotherapy in the multivariate Cox regression analyses (adjusted HR 0.42 [95% CI 0.15–1.17], p = 0.096). However, combination therapy was associated with lower mortality than monotherapy in patients with sepsis or septic shock (adjusted HR 0.94 [95% CI 0.86–1.02], p = 0.047).ConclusionsAppropriate therapy was associated with a protective effect on mortality among patients with BSIs due to Gram-negative pathogens. Combination therapy was associated with improved survival in patients with sepsis or septic shock. Clinicians need to choose optical empirical antimicrobials to improve survival outcomes in patients with BSIs.

Risk Factors Associated with Multi-Drug Resistance in Neonatal Sepsis Caused by Escherichia coli.

An increasing number of cases of neonatal sepsis due to extended-spectrum beta-lactamase (ESBL)-producing multi-drug resistant (MDR) Escherichia coli (E. coli) have been reported worldwide. The aim of this study was to explore the risk factors associated with ESBL-producing MDR E. coli among neonates with culture-confirmed E. coli sepsis and thereby to help selection of appropriate empirical antibiotics. All newborn infants with a confirmed pathogen isolated from blood or cerebrospinal fluid (CSF) from 2016 to 2021 were identified and those with E. coli infection were included in this analysis. We compared a group of neonatal patients with ESBL-producing MDR E. coli sepsis (n=69) to a group with ESBL-negative E. coli (n=70) based on antimicrobial susceptibility reports. We used multivariable regression analysis to determine the risk factors associated with ESBL-producing MDR E. coli strains among the neonates with culture-confirmed E. coli sepsis. ESBL-producing MDR E. coli sepsis was more common in premature infants and newborns with hospital-acquired late-onset sepsis (HALOS). The mortality rate of neonatal sepsis caused by ESBL-producing E. coli was about twice as that of sepsis caused by ESBL-negative E. coli. Antepartum exposure to cephalosporins (OR=25.191, 95% CI: 3.184-199.326, P<0.01) and parenteral nutrition for more than 1 week (OR=4.495, 95% CI: 2.009-10.055, P<0.01) were independent risk factors for neonatal infection with ESBL-producing stains among infants with E. coli sepsis. E. coli remains the most common Gram-negative bacterial pathogen causing neonatal sepsis. A higher proportion of ESBL-producing MDR E. coli is seen in premature infants and those newborns with HALOS and is associated with higher mortality. Antepartum use of cephalosporins and prolonged use of parenteral nutrition may be important factors to consider in the selection of empirical antibiotics for use in neonatal sepsis caused by gram-negative rods prior to the availability of the results of antimicrobial susceptibility.

A Real-world Multicenter Outpatient Experience of Ceftolozane/Tazobactam.

Ceftolozane/tazobactam (C/T) is indicated for the treatment of complicated intra-abdominal infection (IAI), complicated urinary tract infection (UTI), and hospital-acquired/ventilator-associated bacterial pneumonia caused by susceptible bacteria. As real-world data are limited, we report utilization and associated outcomes of C/T use in the outpatient setting. This is a multicenter, retrospective study of patients who received C/T between May 2015 and December 2020. Demographics, infection types, C/T utilization characteristics, microbiology, and health care resource utilization were collected. Clinical success was defined as complete or partial symptom resolution at completion of C/T. Persistent infection and discontinuation of C/T were deemed nonsuccess. Logistic regression analysis was used to identify predictors associated with clinical outcomes. A total of 126 patients (median age, 59 years; 59% male; median Charlson index, 5) from 33 office infusion centers were identified. Infection types included 27% bone and joint infection (BJI), 23% UTI, 18% respiratory tract infection (RTI), 16% IAI, 13% complicated skin and soft tissue infection (cSSTI), and 3% bacteremia. The median daily dose of C/T was 4.5 g, primarily administered via elastomeric pumps as intermittent infusion. The most common gram-negative pathogen was P. aeruginosa (63%), 66% of which was multidrug-resistant and 45% carbapenem-resistant. Enterobacterales was identified in 26% of isolates, of which 44% were extended-spectrum beta-lactamase producers. The overall clinical success rate of C/T was 84.7%. Nonsuccessful outcomes were due to persistent infections (9.7%) and drug discontinuations (5.6%). C/T was successfully used in the outpatient setting to treat a variety of serious infections with a high prevalence of resistant pathogens.