Clinical Epidemiology, Risk Factors, and Control Strategies of Klebsiella pneumoniae Infection

Bacteriophage-embedded and coated alginate layers inhibit biofilm formation by clinical strains of Klebsiella pneumoniae

AIMS

This study aimed to determine the antibiofilm properties of Klebsiella pneumoniae phages previously isolated from Thai hospital sewage water. Furthermore, we aimed to develop a phage-embedded and coated alginate hydrogel, suitable as a wound dressing or surface coating to prevent K. pneumoniae proliferation and biofilm formation.

METHODS AND RESULTS

The biofilm forming capacity of six clinical K. pneumoniae isolates was determined by means of the crystal violet assay and four strains which exhibited strong adherence were selected for further characterization. Two phages (vB_KpnA_GBH014 and vB_KpnM_GBH019) were found to both significantly prevent (P = <0.0005) and disrupt (P = <0.05) biofilms produced by their K. pneumoniae hosts as determined by optical density readings using the crystal violet assay. Furthermore, alginate layers embedded and coated with phages vB_KpnA_GBH014 and vB_KpnM_GBH019 produced antibiofilm surfaces. Viable counts of recovered biofilms showed that alginate hydrogels containing phage vB_KpnA_GBH014 or vB_KpnM_GBH019 were associated with significantly fewer K. pneumoniae vs. no-phage controls (1.61 × 108 cfu ml-1 vs. 1.67 × 104 cfu ml-1, P = <0.005 and 1.78 × 108 cfu ml-1 vs. 6.11 × 102 cfu ml-1, P = <0.00005, respectively). Confocal microscopy further revealed a significant reduction in the biovolume of biofilms formed on phage embedded and coated alginate hydrogels compared to no-phage controls.

CONCLUSIONS

Phages vB_KpnA_GBH014 and vB_KpnM_GBH019 can both prevent and disrupt biofilms produced by clinical isolates of K. pneumoniae. Embedding and coating these phages into alginate produces an antibiofilm matrix which may have promise for coating medical devices or as a wound dressing.

The metagenomic and whole-genome metagenomic detection of multidrug-resistant bacteria from subclinical mastitis-affected cow's milk in India

Multidrug-resistant (MDR) bacteria in farm animal products threaten human health by causing zoonotic infections. The complete genome sequences of MDR bacteria from subclinical mastitis-affected cow's milk have not yet been comprehensively documented in India. In this study, using a bacterial metagenomic sequencing approach, we detected the nearly complete genome sequences of Pseudomonas veronii and Staphylococcus xylosus from subclinical mastitis-affected cow's milk. Furthermore, we sequenced the nearly complete genome sequences of Escherichia coli, Klebsiella pneumoniae, Staphylococcus hominis, and S. xylosus from subclinical mastitis-affected cow's milk using a whole-genome metagenomic sequencing method. Our analysis subsequently revealed that the complete genome sequences of the identified bacteria contained MDR genes and genes for multiple virulence factors. These MDR bacteria may pose a public health risk through exposure to milkers, milk handlers, and farm workers or through the handling and consumption of unpasteurized milk.

Epidemiology and Microbiology of Healthcare-Associated Infections in Neurosurgery Department: A Cross-Sectional Study

Objective: Hospital-acquired infections (HAIs) present a significant challenge in neurosurgical settings. This study aimed to assess the prevalence, risk factors, and clinical impact of HAIs in a neurosurgery department. Methods: A retrospective cross-sectional study was conducted on 5474 patients hospitalized in a neurosurgery department (2019-2023). HAIs were diagnosed in 93 patients (2.7%), accounting for 147 infections. The final cohort included 273 patients: 93 with HAIs and 181 matched controls (age, sex, mortality). Demographic, clinical, and microbiological data were analyzed. Nutritional status was assessed using the Nutritional Risk Screening (NRS, 2002) and consciousness was assessed using the Glasgow Coma Scale (GCS). Infections were classified according to Centers for Disease Control and Prevention (CDC) criteria. Results: The most frequent HAIs were pneumonia (PN, 18.3%), bloodstream infections (BSI, 16.2%), and surgical site infections (SSI, 16.3%). Malnutrition (NRS ≥3) was significantly more common in infected patients (65.6% vs. 11%, p < .001). Patients with GCS ≤8 had higher rates of PN (44.7%) and urinary tract infections (UTI, 32.5%) (p = .004), while GCS 13-15 was linked to SSI (91.7%). HAIs occurred more frequently after emergency procedures (57.8% vs. 30%, p < .0001). Hospital stay was significantly longer in infected patients (40 vs. 5.4 days, p = .001). Klebsiella pneumoniae (15.1%) and Staphylococcus aureus (11.5%) were the most common. Age and sex were not significant risk factors. Conclusion: HAIs in neurosurgical patients are associated with malnutrition and procedural urgency. Targeted infection control, early nutrition support, and antimicrobial stewardship are essential to improving outcomes.

Identification of a novel phage depolymerase against ST11 K64 carbapenem-resistant Klebsiella pneumoniae and its therapeutic potential

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a clinical pathogen with a high mortality rate, and its clinical management and infection control have become a serious challenge. Phage-encoded depolymerase cleaves the capsular polysaccharide, a major virulence factor of K. pneumoniae. This study aimed to identify a phage depolymerase targeting ST11 K64 CRKP, evaluate its antimicrobial activity and therapeutic efficacy, and provide new alternative therapeutic strategies for K64 CRKP. Phages were screened from untreated hospital sewage using clinically isolated CRKP as the host bacterium. The host range, efficiency of plaque formation, optimal multiplicity of infection, adsorption efficiency, and one-step growth curve of phage vB_KpnP_IME1309 were determined by the double-layer agar plate culture method. The morphology of the phage was observed by transmission electron microscopy. Phage nucleic acids were extracted for whole-genome sequencing, and the phage-encoded depolymerase gene ORF37 was amplified by polymerase chain reaction. Next, a recombinant plasmid was constructed to induce depolymerase expression, which was verified using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In vitro bactericidal activity was determined using a combined serum assay, and the anti-K. pneumoniae biofilm effect of depolymerase was determined by crystal violet staining. Finally, a Galleria mellonella larvae infection model was established to investigate the therapeutic effect of depolymerase on larvae in vivo. Here, we isolated and characterized a phage vB_KpnP_IME1309 targeting ST11 K64 CRKP, which featured a latent period of 20 min and a burst size of approximately 290 plaque-forming units/cell. It contained 41 predicted open reading frames, of which ORF37 encoded depolymerase. The expressed and purified depolymerase Dep37 cleaved only ST11 K64 CRKP and formed a translucent halo on the agar plate. Dep37 increased the susceptibility of K. pneumoniae B1 to serum killing, inhibited CRKP biofilm formation, and degraded mature biofilms. The combination of Dep37 and kanamycin was significantly more effective in treating CRKP biofilms compared to either Dep37 or kanamycin alone. An injection of Dep37 at 5 min and 2 h after the CRKP infection of Galleria mellonella larvae increased their survival rates by up to 73% and 53%, respectively. Depolymerase Dep37 may be used as a potential method for capsule typing of K. pneumoniae, showing great promise for the development of novel alternative therapeutic strategies against ST11 K64 CRKP.

IMPORTANCE

A novel phage vB_KpnP_IME1309 targeting ST11 K64 carbapenem-resistant Klebsiella pneumoniae (CRKP) was isolated and characterized. The ORF37 encoding depolymerase gene of phage vB_KpnP_IME1309 was successfully expressed and purified. Depolymerase increases the susceptibility of CRKP to serum killing, inhibits CRKP biofilm formation, and degrades mature biofilms. The combination of depolymerase and kanamycin is significantly more effective than either depolymerase or kanamycin alone in the treatment of CRKP biofilm. Depolymerase injection at 5 min and 2 h after CRKP infection of Galleria mellonella larvae increased the survival rate of larvae by up to 73% and 53%, respectively. Depolymerase Dep37 may be used as a method for the development of novel alternative therapeutic strategies against ST11 K64 CRKP.

Evidence of hypervirulent carbapenem-resistant Klebsiella pneumoniae in cats with urinary affections and associated humans in Egypt

The emergence of hypervirulent and carbapenem-resistant Klebsiella pneumoniae poses a significant threat to the public health of both cats and their owners. Therefore, conducting molecular characterization and phylogenetic analysis of K. pneumoniae strains in both cats and humans in Egypt is crucial. 108 feline and 101 human urine samples were collected and subjected to routine microbiological isolation and molecular identification of K. pneumoniae. Subsequently, phenotypic antimicrobial sensitivity patterns and molecular identification of classical virulence, hypervirulence, and carbapenem resistance genes were examined. A total of 46 K. pneumoniae isolates were recovered, comprising 43.4% (23 out of 53) from diseased humans, 4.17% (2 out of 48) from healthy humans, 22.95% (14 out of 61) from diseased felines, and 14.89% (7 out of 47) from healthy felines. The detection rates for narrow drug-resistant (NDR), multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan drug-resistant (PDR) strains were 41.30%, 54.35%, 2.17%, and 2.17%, respectively. The distribution rates for mrKD, entB, K2, Kfu, and MagA genes were 76.1%, 82.6%, 8.7%, 13.0%, and 0%, respectively. In addition, the distribution of hypervirulence genes was 41.3%, 36.9%, 13.0%, 10.9%, and 17.4% for iucA, iroB, Peg344, rmPA, and rmPA2, respectively, and 43.5%, 30.4%, 19.6%, and 52.2% for NDM, OXA-48, VIM, and KPC resistance genes, respectively. Phylogenetic analysis of the entB gene from four recovered strains revealed a relationship between feline strains and other human strains. In conclusion, this study focused on the molecular characterization and phylogenetic analysis of hypervirulent and carbapenem-resistant K. pneumoniae in companion cats and humans in Egypt.

A systematic review of hypervirulent Klebsiella pneumoniae research: bibliometric and topic modeling perspectives

Background/objective

Hypervirulent Klebsiella pneumoniae (hvKP) is an emerging global health threat, exhibiting increased virulence and multidrug resistance compared to classic K. pneumoniae. Understanding the research landscape surrounding hvKP is crucial for developing effective control strategies. This study aimed to comprehensively analyze the global research trends in hvKP from 2013 to 2024 using bibliometric and topic modeling techniques.

Methods

Data from 1,014 articles on hvKP, retrieved from the Web of Science Core Collection, were analyzed using Bibliometrix, CiteSpace, and VOSviewer to assess publication trends, collaborations, geographical distribution, and keyword co-occurrence. Latent Dirichlet Allocation (LDA) topic modeling was employed to identify key research themes.

Results

The analysis revealed a steadily increasing volume of hvKP research, with China and the United States as major contributors. Four primary research themes emerged: high virulence phenotypes and mechanisms; drug resistance and treatment strategies; genetic and molecular mechanisms; and epidemiological and transmission characteristics. Research hotspots included virulence mechanisms, drug resistance, genomic detection approaches, and epidemiological features.

Conclusion

This bibliometric analysis provides a comprehensive overview of hvKP research, highlighting key trends and research gaps. The identified research hotspots inform future research directions and contribute to the development of effective strategies for combating hvKP infections. The increasing research volume underscores the urgent need for continued investigation into this significant public health threat.

New insights and perspectives on the virulence of hypervirulent Klebsiella pneumoniae

Klebsiella pneumoniae, a Gram-negative bacterium, comprises strains with diverse virulence potentials, ranging from classical to hypervirulent variants. Understanding the genetic basis underlying the virulence disparities between hypervirulent (hvKp) and classical K. pneumoniae (cKp) strains is crucial. hvKp strains are characterized by hypermucoviscosity, attributed to the presence of specific virulence genes and the production of molecules that aid in their ability to survive, evade host immune defenses, and cause infection. In contrast, classical strains exhibit a broader array of antimicrobial resistance determinants, conferring resistance to multiple antibiotics. Although current definitions of hvKp incorporate clinical features, phenotypes, and genotypes, identifying hvKp strains in clinical settings remains challenging. Genomic studies have been pivotal and have helped to identify distinct genetic profiles in hvKp strains, including unique virulence plasmids and chromosomal variations, underscoring the genetic diversity within K. pneumoniae populations. This review examines the virulence and genetic determinants associated with hvKp. The presence of genes defining hypervirulence, alongside considerations of their utility as biomarkers and targets for therapeutic strategies, is discussed, while also providing insight into biofilm formation by hvKp and key questions that need urgent responses in understanding hvKp.

Epidemiology and Clinical Impact of Vancomycin-Resistant Enterococcus at King Abdulaziz University Hospital (2015-2022): Prevalence, Risk Factors, and Mortality

Background

Enterococcus faecalis and Enterococcus faecium are part of the human microbiota but pose significant risks in clinical settings due to increasing antimicrobial resistance. Vancomycin-resistant enterococci (VRE) are a growing concern, linked to high morbidity and mortality in hospitalized patients.

Aim

This study is the first comprehensive investigation of VRE prevalence and associated risk factors at King Abdulaziz University Hospital (KAUH) from 2015 to 2022.

Methods

Clinical samples were collected, and VRE isolates were identified using VRE Card GeneXpert, BioFire PCR, and the VITEK 2 system. Descriptive statistical analysis with Stata version 17 summarized patient characteristics, including demographics, comorbidities, hospital exposure, and laboratory findings. Categorical variables were reported as frequencies/percentages, while continuous variables were expressed as mean ± SD or median [IQR].

Results

Among 254 adult patients with VRE infections, the median age was 61 years. The most common comorbidities were diabetes, hypertension, and kidney disease. VRE infections peaked in 2021, with urine cultures being the most frequent source. Most patients had prior antibiotic exposure, particularly to vancomycin and carbapenems. Enterococcus faecium was the predominant species, with the VanA phenotype being most common. Alarmingly, 61.8% of VRE-infected patients died during the study period.

Conclusion

These findings underscore the critical need for enhanced infection control measures and antimicrobial stewardship to combat VRE and improve patient outcomes.

Investigation of the Possible Antibacterial Effects of Corticioid Fungi Against Different Bacterial Species

Extracts from 58 species of corticioid fungi (phylum Basidiomycota), mainly belonging to the orders Hymenochaetales, Polyporales and Russulales, were tested for their inhibitory activity against five species of bacteria: Corynebacterium striatum, Haemophilus influenzae, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Twenty-four of the species we analyzed in this study were tested for antibacterial activity for the first time. The fruiting bodies of the fungi were collected from dead wood in the forests of north-eastern Poland, and macerated in methanol. Dried extracts were redissolved in dimethyl sulfoxide and applied to broth cultures of the bacteria, which were then inoculated on agar plates. Noblesia crocea demonstrated moderate inhibitory activity against all five tested bacteria; Amylocorticium subincarnatum, Laxitextum bicolor, Peniophora laeta, P. rufomarginata, Phanerochaete sordida, and Xylobolus frustulatus inhibited four bacterial species. The extracts from 14 fungal species tested were moderately active against only two bacteria, P. aeruginosa and C. striatum; 17 species were active against C. striatum only. The full inhibition was observed with concentrations of extract 25 or 50 mg/mL.

Clinical scoring model for predicting cefotaxime-resistance in Klebsiella pneumoniae bacteremia: development and validation based on portal of entry

We developed a prediction model for cefotaxime resistance in patients with K. pneumoniae bacteremia. Adult patients with K. pneumoniae bacteremia were grouped into derivation (from March 2018 to December 2019) and validation (from January 2020 to August 2020) cohorts. The prediction scoring system was based on factors associated with cefotaxime resistance identified by the logistic regression model. A total of 358 patients were enrolled (256 for derivation, 102 for validation). In the multivariable analysis, age ≥65 years, hospital-acquired infection, prior antimicrobial use, and an updated Charlson comorbidity index ≥3 points were associated with cefotaxime resistance in the derivation cohort. When each variable was counted as 1 point, the values of the area under the curve were 0.761 in the derivation and 0.781 in the validation cohorts. The best cutoff value using the Youden index was ≥2 with 73.6% sensitivity and 67.5% specificity. Our simple scoring system favorably predicted cefotaxime resistance.

The first report of antibiotic resistance and virulence factor profiles in multidrug-resistant clinical isolates of Klebsiella pneumoniae from Pontianak, Indonesia

BACKGROUND

Klebsiella pneumoniae is known as one of the most common causes of hospitalacquired infections. Its prevalence poses substantial challenges to both hospital and public health systems, particularly due to the rise of multidrug-resistant strains. Understanding the epidemiology and resistance properties of K. pneumoniae can inform antimicrobial stewardship and infection control programs. A cross-sectional study was employed from November 2021 to November 2023.

METHODS

A total of 24 isolates underwent antimicrobial susceptibility testing using the disk diffusion method, an extended-spectrum beta-lactamase (ESBL) production test, and molecular gene detection.

RESULTS

The study found that 95.8% of clinical isolates were classified as multidrug-resistant. All isolates were resistant to ampicillin (100%). A high percentage of isolates were resistant to cefazolin (91.7%), ceftriaxone (87.5%), cefotaxime (87.5%), cefepime (87.5%), ciprofloxacin (83.3%), and sulfamethoxazole-trimethoprim (83.3%). Of the 24 isolates, 87.5% harbored ESBL genes, while the frequencies for GES, NDM, SIM, and OXA-48 were 16.7%, 20.8%, 8.3%, and 41.7%, respectively. Notably, the OXA-23 and OXA-51 genes, which are typically associated with Acinetobacter baumannii, were detected in 16.7% and 20.8% of isolates, respectively. Moreover, the prevalence of virulence genes rmpA, acrAB, and tolC was 0%, 95.8%, and 87.5%, respectively.

CONCLUSION

This study demonstrated a high level of antibiotic resistance and a significant presence of virulence genes among K. pneumoniae isolates. Consequently, these findings represent a critical public health issue that requires heightened awareness among all stakeholders, including health workers.

Unveiling the impact: COVID-19's influence on bacterial resistance in the Kingdom of Bahrain

BACKGROUND

Antibiotic resistance is a growing global health threat, and understanding local trends in bacterial isolates and their susceptibility patterns is crucial for effective infection control and antimicrobial stewardship. The coronavirus disease 2019 (COVID-19) pandemic has introduced additional complexities, potentially influencing these patterns.

AIM

To analyze trends in bacterial isolates and their antibiotic susceptibility patterns at Salmaniya Medical Complex from 2018 to 2023, with a specific focus on the impact of the COVID-19 pandemic on these trends.

METHODS

A retrospective analysis of microbiological data was conducted, covering the period from 2018 to 2023. The study included key bacterial pathogens such as Escherichia coli (E. coli), Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus, among others. The antibiotic susceptibility profiles of these isolates were assessed using standard laboratory methods. To contextualize the findings, the findings were compared with similar studies from other regions, including China, India, Romania, Saudi Arabia, the United Arab Emirates, Malaysia, and United States.

RESULTS

The study revealed fluctuating trends in the prevalence of bacterial isolates, with notable changes during the COVID-19 pandemic. For example, a significant increase in the prevalence of Staphylococcus aureus was observed during the pandemic years, while the prevalence of E. coli showed a more variable pattern. Antibiotic resistance rates varied among the different pathogens, with a concerning rise in resistance to commonly used antibiotics, particularly among Klebsiella pneumoniae and E. coli. Additionally, the study identified an alarming increase in the prevalence of multidrug-resistant (MDR) strains, especially within Klebsiella pneumoniae and E. coli isolates. The impact of the COVID-19 pandemic on these trends was evident, with shifts in the frequency, resistance patterns, and the emergence of MDR bacteria among several key pathogens.

CONCLUSION

This study highlights the dynamic nature of bacterial isolates and their antibiotic susceptibility patterns at Salmaniya Medical Complex, particularly in the context of the COVID-19 pandemic. The findings underscore the need for continuous monitoring and effective anti-microbial stewardship programs to combat the evolving threat of antibiotic resistance. Further research and policy initiatives are required to address the identified challenges and improve patient outcomes in the face of these ongoing challenges.

Elucidation of the possible synergistic effect of Torulaspora delbrueckii and ciprofloxacin in a rat model of induced pulmonary fibrosis and infected with Klebsiella pneumonia: An in vivo study

The lungs are constantly subjected to enormous amounts of air and potentially transmitted agents, leading to a high incidence of severe and complex ailments urging the demand for defensive actions to maintain their regular function. Numerous studies have demonstrated how certain probiotics have many advantages including hindering pulmonary exacerbations in individuals with cystic fibrosis, which encourages the idea of combining them with approved antibiotics as a therapeutic choice for treatment patients with lung fibrosis who also have bacterial infections. This investigation aimed to test the possibility of a combination of Torulaspora delbrueckii as a probiotic with ciprofloxacin in an animal model having pulmonary fibrosis with a moderate load of Klebsiella pneumonia. Ninety adult male rats were split into six groups (15 rats/each): GI (control), GII (lung fibrosis), GIII (lung fibrosis infected by K. pneumonia), GIV (lung fibrosis infected by K. pneumonia then treated with ciprofloxacin), GV (lung fibrosis infected by K. pneumonia and fed with T. delbrueckii) and GVI (lung fibrosis infected by K. pneumonia then treated with combined therapy of ciprofloxacin and T. delbrueckii) for 28 days. Survival rate and bacterial load were determined in various experimental animal groups. Histological variations were examined as well as scanning electron microscopy. Gene expression, various levels of cytokines, redox enzymes, and oxidative stress markers were assessed and compared in different tested groups. The treatment using a combination of T. delbrueckii and ciprofloxacin is suggested as a new method to treat induced lung fibrosis in animals and infected with K. pneumonia as a possible option in complicated infection.

Phage-antibiotic combinations against Klebsiella pneumoniae: impact of methodological approaches on effect evaluation

Background

The combined use of bacteriophages and antibiotics represents a promising strategy for combating multidrug-resistant bacterial pathogens. However, the lack of uniformity in methods for assessing combination effects and experimental protocols has resulted in inconsistent findings across studies. This study aimed to evaluate the effects of interactions between phages and antibiotics on Klebsiella pneumoniae strains using various statistical approaches to formalize combination effects.

Methods

Effects were assessed for four antibiotics from distinct classes (gentamicin, levofloxacin, meropenem, chloramphenicol), three phages from different genera (Dlv622, Seu621, FRZ284), and a depolymerase (Dep622) on three K. pneumoniae strains of the KL23 capsule type. Antibiotics were used at Cmax concentrations, and phages at sublethal levels. A modified t-test, Bliss independence model, two-way ANOVA, and checkerboard assay were employed to evaluate the results.

Results

Among 48 combinations, 33 effects were statistically significant, including 26 cases of synergy and 7 of antagonism. All statistical methods showed consistency in identifying effects; however, the t-test and Bliss method detected a greater number of effects. The strongest synergy was observed with levofloxacin in combination with Seu621 or Dep622 across all bacterial strains. Checkerboard assays confirmed synergy in selected cases but indicated that combined effects could vary with antimicrobial concentrations.

Conclusion

The choice of analytical method substantially impacts the detection of phage-antibiotic effects. The t-test and Bliss method, due to their simplicity and sensitivity, may be optimal for clinical application, while two-way ANOVA for confirming strong interactions. These results emphasize the need to consider interaction characteristics when designing therapeutic strategies.

Complete genome sequences of Klebsiella pneumoniae, Klebsiella quasipneumoniae, and Klebsiella variicola clinical isolates from an epidemiology study

An epidemiology study of Klebsiella spp. causing infections was carried out. In the study, K. pneumoniae was identified with a prevalence of 94.6%, K. quasipneumoniae with 3.8%, and K. variicola with 1.6%. Here, we report the draft genome sequence of four selected Klebsiella pneumoniae species complex (KpSC) clinical isolates obtained from different sources.

Computational design of a fimbriae-derived multi-epitope vaccine candidate against Klebsiella pneumoniae

Klebsiella pneumoniae is a pathogen that causes infections in various parts of the body, with high mortality rates reported in antibiotic-resistant cases. Treating at-risk individuals requires crucial vaccination efforts due to the challenges that exist. This research involved designing a multi-epitope vaccine from K. pneumoniae's fimbriae antigens. Optimal T-cell and B-cell epitopes were chosen through in silico studies including epitope-HLAs molecular docking. The multi-epitope was created, featuring antigenic T- and B-cell epitopes, β-defensin as an adjuvant, the PADRE sequence to boost immunogenicity and well-suited linkers. The tertiary structure of the multi-epitope was achieved through modeling and molecular dynamics-based refinements. The construct underwent scrutiny for structural traits, physicochemical properties, conformational B epitope prediction, immune responses simulation, in silico cloning, molecular docking for assay binding to toll-like receptors (TLRs), and deformability studies. The outcomes indicated the vaccine candidate's positive attributes, encompassing immunogenicity, structure, physicochemical properties, solubility, TLR binding, toxicity, stability, allergenicity, and cross-reactivity. The multi-epitope vaccine candidate exhibits the potential for provoking diverse immune responses against K. pneumoniae. Nevertheless, additional in vitro and in vivo experimental tests are necessary to substantiate its efficacy.

Genomic relatedness of colonizing and invasive disease Klebsiella pneumoniae isolates in South African infants

Klebsiella pneumoniae (KPn) colonizes multiple anatomical sites and is a leading cause of invasive disease and death in African children; however, there is no comparative genomic analysis between colonizing and invasive strains. This study investigated the genomic relatedness of KPn colonizing and invasive isolates in South African infants; and evaluated the relative invasiveness of KPn isolates based on sequence types (ST), capsular (KL), and lipopolysaccharide (O) loci by calculating case-carrier ratios (CCRs). There was less genomic diversity amongst invasive (22 ST, 17 K-loci) than colonizing isolates (31 ST, 29 K-loci), with invasive isolates being 8.59-fold and 3.49-fold more likely to harbour genes encoding for multi-drug resistance and yersiniabactin production compared with colonizing isolates. The CCRs for KL102 and O1/O2v2 were > 1, and < 1 for KL8, ST1414, and O1O2v1. Identifying high-risk strains, including KL102 and O1O2v2, that may have a higher potential to cause invasive disease, could enhance risk assessment and management strategies in vulnerable populations.

Emergence of Tigecycline-Nonsusceptible Carbapenem-Resistant Klebsiella pneumoniae with Metallo-β-Lactamase and Transferable Ceftazidime-Avibactam Resistance in China

In recent years, resistance of Klebsiella pneumoniae to the clinical last-resort drugs carbapenem and tigecycline has intensified, including Metallo-β-Lactamase-producing K. pneumoniae (MBL-KP), which demonstrated resistance to ceftazidime-avibactam (CZA), posing a significant public health threat. This study focused on the carbapenems, CZA, and tigecycline resistance mechanisms of MBL-producing Carbapenem-resistant K. pneumoniae (MBL-CRKP). A retrospective study and genomic epidemiological analysis of Carbapenem-resistant K. pneumoniae (CRKP) strains isolated from Yangzhou City, Jiangsu Province, China, between 2016 and 2023 was conducted. The detection rate of CRKP in Yangzhou City has increased significantly in recent years, with five strains carrying the Metallo-β-Lactamases (MBLs) gene, all of which exhibited resistance to carbapenems and CZA. Two strains even showed reduced susceptibility to tigecycline, with one harboring tmexCD2-toprJ2. Moreover, three CRKP strains carrying both blaKPC-2 and blaNDM-1/blaNDM-29 genes were identified. Plasmids carrying MBL genes can horizontally transfer, leading to the spread of resistance, thus further exacerbating the difficulty of clinical treatment and the spread of resistance. In conclusion, this study not only revealed the resistance of MBL-CRKP strains to clinical last-resort therapeutic drugs but also explored the resistance mechanism and horizontal transfer through genomic analysis. Moreover, this study also suggested that microbial drug resistance surveillance should be conducted from the perspective of "one health" in the future to combat this global health challenge.

A novel approach to antimicrobial resistance: Machine learning predictions for carbapenem-resistant Klebsiella in intensive care units

This study was conducted at Kocaeli University Hospital in Turkey and aimed to predict carbapenem-resistant Klebsiella pneumoniae infection in intensive care units using the Extreme Gradient Boosting (XGBoost) algorithm, a form of artificial intelligence. This was a retrospective case-control study involving 289 patients, including 159 carbapenem-resistant and 130 carbapenem-susceptible individuals as controls. The model's predictive analysis combined a diverse range of demographic, clinical, and laboratory data, resulting in an average accuracy of 83.0%, precision of 83%, sensitivity of 88%, F1 score of 85%, and Matthews Correlation Coefficient of 0.66. Prolonged hospitalization and intensive care unit stay were significant predictors of carbapenem-resistant Klebsiella pneumoniae infection. The role of artificial intelligence role in healthcare, particularly in ICUs for managing antibiotic-resistant infections, is a major development in medicine. This study emphasizes the potential of artificial intelligence to predict antimicrobial resistance and improve clinical decisions in resource-limited settings. The study was approved by ClinicalTrials.gov (trial registration number NCT05985057 on 02.08.2023).

Epidemiology and Antibiotic Resistance Patterns of Klebsiella pneumoniae Infections Among Female Patients of a Long-Term Care Hospital in Saudi Arabia

BACKGROUND

 Klebsiella pneumoniae is a gram-negative bacterium naturally found in the gastrointestinal and oropharyngeal tracts but can become an opportunistic pathogen, causing severe healthcare-associated infections, especially in immunocompromised patients. This study aimed to investigate the epidemiology and antibiotic resistance patterns of K. pneumoniae infections among female patients in a long-term care hospital in Riyadh, Saudi Arabia.

METHODS

A cross-sectional retrospective study examined microbial cultures of 27 female patients with confirmed positive cultures of K. pneumoniae who were admitted to a long-term care hospital in Riyadh. Demographic information, in addition to culture sites and antibiotic susceptibility tests, was collected. The associations between patient characteristics and resistance patterns were investigated, focusing on the prevalence of carbapenem-resistant Enterobacterales (CRE) and the production of extended-spectrum beta-lactamases (ESBL).

RESULTS

A total of 51.9% (n = 14) of CRE K. pneumoniae isolates were reported, indicating substantial antibiotic resistance. Patients with bedsores exhibited a lower CRE infection proportion (18.5%) compared to those without bedsores (33.3%), with no statistically significant difference (p = 0.888). Older age (>50 years) demonstrated a higher CRE infection prevalence (29.6%) compared to younger patients (22.2%), with no statistical significance (p = 0.351). Further, all patients reported the widespread use of Foley catheters, and tracheostomy or hospital stay duration did not significantly correlate with resistance patterns. Notably, imipenem exhibited the highest susceptibility rate (66.7%), whereas cotrimoxazole (51.9%) and ampicillin (33.3%) demonstrated a high resistance.

CONCLUSION

 This study highlights the increasing prevalence of CRE and ESBL-producing K. pneumoniae infections among female long-term care patients, underscoring the need for enhanced infection control strategies and antimicrobial stewardship programs to mitigate the spread of multidrug-resistant (MDR) pathogens. Targeted interventions, particularly for high-risk patients, are essential for reducing antimicrobial resistance in long-term care settings. Future research should include larger cohorts to further investigate gender-based differences in K. pneumoniae resistance patterns.

Bacterial profile, antimicrobial susceptibility patterns, and associated factors among lower respiratory tract infection patients attending at Debre Markos comprehensive specialized hospital, Northwest, Ethiopia

BACKGROUND

Lower respiratory tract infections are the most common health problem, demanding frequent consultation and hospitalization. Moreover, there has been a dramatic rise in antibiotic resistance among respiratory pathogens.

OBJECTIVE

This study aimed to assess the bacterial profile, antimicrobial susceptibility patterns, and associated factors of lower respiratory tract infection among patients attending at Debre Markos Comprehensive Specialized Hospital, Northwest Ethiopia, in 2023.

METHOD

A hospital-based cross-sectional study was conducted on a total of 305 study participants from May 1 to July 30, 2023. Purulent sputum samples were collected and streaked onto chocolate agar, blood agar, and MacConkey agar. Chocolate agar and blood agar plates were incubated at 35-37 °C for 24 h with 5% carbon dioxide in a candle jar. MacConkey agar was incubated aerobically at 35-37 °C for 24 h. Antimicrobial susceptibility patterns were determined via the disk diffusion method (Kirby-Bauer) on Mueller-Hinton agar. A logistic regression model was used to show the relationship between the outcome and independent variables.

RESULT

Of a total of 305 samples, 33.4% (95% CI: 29.2-38.8%) samples showed growth of various species of bacteria. The predominant pathogens were Klebsiella pneumoniae 31/102 (30.4%), Streptococcus pneumoniae 21/102 (20.6%), and Pseudomonas aeruginosa 16/102 (15.7%). The overall magnitude of multidrug resistance (MDR) was 47.1%. Having > 58 age groups (AOR = 7.180, 95% CI: 1.858-27.743), being illiterate (AOR = 2.76, 95 CI: 1.158-6.578), chronic cough (AOR = 5.26, 95% CI: 1.725-16.038), and alcohol drinking (AOR = 6.542, 95% CI: 2.570-16.654), were determinants of lower respiratory tract infection.

CONCLUSION

K. pneumoniae and S. pneumoniae were the most predominant pathogens. A high levels antibiotic resistance was present in the majority of the isolates. Therefore, antibiotic susceptibility testing should be applied to guide treatment decisions.

A model for predicting bacteremia species based on host immune response

Introduction

Clinicians encounter significant challenges in quickly and accurately identifying the bacterial species responsible for patient bacteremia and in selecting appropriate antibiotics for timely treatment. This study introduces a novel approach that combines immune response data from routine blood counts with assessments of immune cell activation, specifically through quantitative measurements of Rho family GTPase activity. The combined data were used to develop a machine-learning model capable of distinguishing specific classes of bacteria and their associations.

Methods

We aimed to determine whether different classes of bacteria elicit distinct patterns of host immune responses, as indicated by quantitative differences in leukocyte populations from routine complete blood counts with differential. Concurrently, we conducted quantitative measurements of activated Rac1 (Rac1•GTP) levels using a novel 'G-Trap assay' we developed. With the G-Trap, we measured Rac1•GTP in peripheral blood monocytes (PBMC) and polymorphonuclear (PMN) cells from blood samples collected from 28 culture-positive patients and over 80 non-infected patients used as controls.

Results

Our findings indicated that 18 of the 28 patients with bacteremia showed an increase of ≥ 3-fold in Rac1•GTP levels compared to the controls. The remaining ten patients with bacteremia exhibited either neutrophilia or pancytopenia and displayed normal to below-normal Rac1 GTPase activity, which is consistent with bacteria-induced immunosuppression. To analyze the data, we employed partial least squares discriminant analysis (PLS-DA), a supervised method that optimizes group separation and aids in building a novel machine-learning model for pathogen identification.

Discussion

The results demonstrated that PLS-DA effectively differentiates between specific pathogen groups, and external validation confirmed the predictive model's utility. Given that bacterial culture confirmation may take several days, our study underscores the potential of combining routine assays with a machine-learning model as a valuable clinical decision-support tool. This approach could enable prompt and accurate treatment on the same day that patients present to the clinic.

Comparative analysis of clinical characteristics and outcomes between carbapenem-resistant and carbapenem-sensitive Klebsiella pneumoniae infections: insights from a tertiary hospital in Northern China

Background

To compare the risk factors, clinical outcomes, and mortality rates between carbapenem-resistant Klebsiella pneumoniae (CRKP) and carbapenem-sensitive Klebsiella pneumoniae (CSKP) infections.

Methods

A retrospective cohort study was conducted on patients with Klebsiella pneumoniae infections admitted to a tertiary hospital in Zhangjiakou, China. The research period is from January 2021 to December 2022. Data were analyzed using SPSS 24.0 and R. Univariate analysis identified potential risk factors for CRKP infections using appropriate statistical methods, followed by multivariable logistic regression to determine independent risk factors. Mortality rates between CRKP and CSKP groups were compared using chi-square tests, and survival curves were generated with the Kaplan-Meier method.

Results

The study included 283 patients, with 104 (36.7%) infected by CRKP and 179 (63.3%) by CSKP. CRKP patients had significantly higher body temperature, white blood cell counts, and inflammatory markers, while showing lower diastolic blood pressure and oxygen saturation (p < 0.05). CRKP infections were predominantly found in the ICU (49%) and mainly isolated from sputum (59%). Independent risk factors for CRKP included elevated C-reactive protein (OR = 1.02) and solid tumors (OR = 18.186). CRKP patients experienced longer hospital stays (25 days vs. 12 days for CSKP), longer ICU stays (13 days vs. 7 days), and higher 30-day mortality (23.1% vs. 17.9%, p = 0.012). The deceased group had elevated procalcitonin and creatinine levels, longer prothrombin time, and a greater need for mechanical ventilation compared to survivors (p < 0.05).

Conclusion

Patients with CRKP infections had higher mortality rates and longer hospital stays than those with CSKP infections. Previous hospitalization, hospitalization in an ICU, and mechanical ventilation were independent risk factors for CRKP infection.

Patient characteristics and antimicrobial susceptibility profiles of Escherichia coli and Klebsiella pneumoniae infections in international travellers: a GeoSentinel analysis

BACKGROUND

Antimicrobial resistance (AMR) is a global health crisis, with Enterobacterales, including Escherichia coli and Klebsiella pneumoniae, playing significant roles. While international travel to low- and middle-income countries is linked to colonization with AMR Enterobacterales, the clinical implications, particularly the risk of subsequent infection, remain unclear due to limited data. We aimed to characterize E. coli and K. pneumoniae infections in travellers and the antimicrobial susceptibility profiles of their isolates.

METHODS

We analysed data on E. coli and K. pneumoniae infections in travellers collected at GeoSentinel sites between 2015 and 2022, focusing on epidemiological, clinical and microbiological characteristics. We defined multi-drug resistance (MDR) as non-susceptibility to agents from at least three drug classes.

RESULTS

Over the 8-year period, we included 655 patients (median age 41 years; 74% female) from 57 sites in 27 countries, with 584 E. coli and 72 K. pneumoniae infections. Common travel regions included sub-Saharan Africa, Southeast Asia and South-Central Asia. Urinary tract infections predominated. Almost half (45%) were hospitalized. Among infections with antimicrobial susceptibility data across three or more drug classes, 203/544 (37%) E. coli and 19/67 (28%) K. pneumoniae demonstrated MDR. Over one-third of E. coli and K. pneumoniae isolates were non-susceptible to third-generation cephalosporins and cotrimoxazole, with 38% and 28% non-susceptible to fluoroquinolones, respectively. Travellers to South-Central Asia most frequently had isolates non-susceptible to third-generation cephalosporins, fluoroquinolones and carbapenems. We observed increasing frequencies of phenotypic extended spectrum beta-lactamase and carbapenem resistance over time.

CONCLUSIONS

E. coli and K. pneumoniae infections in travellers, particularly those to Asia, may be challenging to empirically treat. Our analysis highlights the significant health risks these infections pose to travellers and emphasizes the escalating global threat of AMR. Enhanced, systematic AMR surveillance in travellers is needed, along with prospective data on infection risk post travel-related AMR organism acquisition.

Klebsiella spp. in healthy pigs: reservoirs of antimicrobial resistance and potential pathogenic threats

AIM

The aim of this study was to isolate Klebsiella spp. from clinically healthy animals fed diets with or without antimicrobial growth promoters (AGP). Additionally, the study evaluated whether the inclusion of growth promoters affected the recovery of multi-drug-resistant isolates.

METHODS AND RESULTS

A total of 144 isolates were obtained from rectal swabs on Simmons citrate agar supplemented with 1% inositol. Of these, 45 non-replicative isolates underwent extensive characterization, including molecular and phenotypic analyses. Sequencing identified that 77% were Klebsiella pneumoniae, 14.5% K. aerogenes, and 8.5% K. variicola. Isolates exhibiting the same polymorphic profiles were detected across different animals and treatments, with and without AGP. Seventy-one percent were multidrug-resistant, as determined by disk diffusion testing. The isolates harbored genes such as mcr-1, blaCTX-M-2, sul2, tetB, qnrS, and dfrA, among others. Additionally, genes encoding siderophores like enterobactin, aerobactin, and yersiniabactin were detected via Polymerase Chain Reaction (PCR). Thirty-nine isolates were strong biofilm producers, 45% moderate, and 16% weak in vitro tests. The predominant genetic profiles included single, double, or triple-locus variants of ST25, ST147, and ST4691. Two novel sequence types were identified: ST7694 (K. pneumoniae) and ST7699 (K. variicola). Survival and persistence analyses in Galleria mellonella showed that these isolates exhibited a virulent phenotype and an enhanced capacity for multiplication in the early hours of infection.

CONCLUSION

Clinically healthy swine act as reservoirs for multidrug-resistant Klebsiella spp. exhibiting significant virulence phenotypes. The identification of novel sequence types contributes to epidemiological surveillance and the One Health framework.

Ceftazidime/avibactam versus polymyxin B in carbapenem-resistant Klebsiella pneumoniae infections: a propensity score-matched multicenter real-world study

OBJECTIVES

In this retrospective observational multicenter study, we aimed to assess efficacy and mortality between ceftazidime/avibactam (CAZ/AVI) or polymyxin B (PMB)-based regimens for the treatment of Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections, as well as identify potential risk factors.

METHODS

A total of 276 CRKP-infected patients were enrolled in our study. Binary logistic and Cox regression analysis with a propensity score-matched (PSM) model were performed to identify risk factors for efficacy and mortality.

RESULTS

The patient cohort was divided into PMB-based regimen group (n = 98, 35.5%) and CAZ/AVI-based regimen group (n = 178, 64.5%). Compared to the PMB group, the CAZ/AVI group exhibited significantly higher rates of clinical efficacy (71.3% vs. 56.1%; p = 0.011), microbiological clearance (74.7% vs. 41.4%; p < 0.001), and a lower incidence of acute kidney injury (AKI) (13.5% vs. 33.7%; p < 0.001). Binary logistic regression revealed that the treatment duration independently influenced both clinical efficacy and microbiological clearance. Vasoactive drugs, sepsis/septic shock, APACHE II score, and treatment duration were identified as risk factors associated with 30-day all-cause mortality. The CAZ/AVI-based regimen was an independent factor for good clinical efficacy, microbiological clearance, and lower AKI incidence.

CONCLUSIONS

For patients with CRKP infection, the CAZ/AVI-based regimen was superior to the PMB-based regimen.

Isolation and Characterization of Colistin-Resistant Enterobacteriaceae from Foods in Two Italian Regions in the South of Italy

The emergence of colistin-resistant Enterobacteriaceae in food products is a growing concern due to the potential transfer of resistance to human pathogens. This study aimed to assess the prevalence of colistin-resistant Enterobacteriaceae in raw and ready-to-eat food samples collected from two regions of Italy (Apulia and Basilicata) and to evaluate their resistance phenotypes and genetic characteristics. A total of 1000 food samples were screened, with a prevalence of 4.4% of colistin-resistant Enterobacteriaceae. The majority of the isolates belonged to Enterobacter spp. (60%), followed by Moellerella wisconsensis, Atlantibacter hermannii, Klebsiella pneumoniae, and Escherichia coli, among others. Genomic sequencing and antimicrobial susceptibility testing revealed high levels of resistance to β-lactams, with most isolates exhibiting multidrug resistance (MDR). Notably, seven isolates harbored mcr genes (mcr-1, mcr-9, and mcr-10). Additionally, in four of them were predicted the IncHI2 plasmids, known to facilitate the spread of colistin resistance. Furthermore, 56 antimicrobial resistance genes were identified, suggesting the genetic mechanisms underlying resistance to several antibiotic classes. Virulence gene analysis showed that E. coli and other isolates carried genes linked to pathogenicity, increasing the potential risk to public health. This study emphasizes the role of food as a potential reservoir for colistin-resistant bacteria and the importance of monitoring the spread of AMR genes in foodborne pathogens.

Molecular Characterization and Risk Factors of Carbapenem-Resistant Hypervirulent Klebsiella pneumoniae Isolated from Chinese Tertiary Hospital

Background

Therefore, the objectives of this study were to investigate the prevalence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp) in Fujian Medical University Union Hospital, identify their genetic characters, characterize their resistance profiles, and identify risk factors for their infection to improve prevention and treatment strategies for CR-hvKp in the area.

Methods

Between January 2021 and January 2022, clinically identified carbapenem-resistant Klebsiella pneumoniae (CRKp) isolates were collected. A PCR assay was used to detect the K capsule type, virulence genes, carbapenemase genes, and membrane pore protein. ERIC-PCR was carried out for homology analysis. Antimicrobial susceptibility test was used to determine drug resistance. Logistic multivariate regression analysis was conducted to confirm the risk factors for CR-hvKp infection.

Results

In total, 239 CRKp isolates were obtained. The virulence genes with the highest detection rates were mrkD, iucA, and rmpA2. Of these isolates, 54 (22.59%) carried both iucA and rmpA2, thus classifying them as CR-hvKp. All CR-hvKp isolates carried bla KPC. Furthermore, capsular serotypes K64 (94.44%) and K47 (3.70%) were detected. Resistance was observed against most common antibiotics, with the exception of complete sensitivity to ceftazidime-avibactam. ERIC-PCR indicated a potential clonal spread among CR-hvKp. Multivariate analysis found that changing beds was a risk factor for CR-hvKp infection.

Conclusion

Currently, the hospital predominantly carries K64 CR-hvKp that harbors the bla KPC. Our study found that changing patient beds was an independent risk factor for CR-hvKp infection.

Investigation of Colistin resistance and method comparison in Klebsiella pneumoniae strains

PURPOSE

This study aimed to assess the prevalence of colistin resistance in the study group and compare alternative methods with the gold standard. It sought to evaluate the prevalence of plasmid-mediated colistin resistance genes.

MATERIAL AND METHODS

The colistin susceptibility of 151 K. pneumoniae strains was determined using Sensititre™, CBDE, ETEST®, and VITEK®2. Results were compared with BMD. The presence of the mcr gene was assessed using polymerase chain reaction.

RESULTS

The colistin resistance rate was 16,6 %. The categorical agreement of Sensititre™, CBDE, and ETEST® was 100 %. VITEK®2 had a CA of 98 %, a major error of 0.79 %, and a very major error of 8 %. Essential agreement for Sensititre™, ETEST®, and VITEK®2 was 92.7 %, 52.3 %, and 78.1 %, respectively. There were no mcr genes in any strains.

CONCLUSIONS

Due to the difficulty of applying BMD, colistin resistance data are insufficient globally. Continuous epidemiological studies and validation of alternative methods are needed.

Phage Therapy: A Promising Treatment Strategy against Infections Caused by Multidrug-resistant Klebsiella pneumoniae

Klebsiella pneumoniae (KP) is a common and highly pathogenic pathogen, which often causes several serious infections in humans. The rampant and inappropriate use of broad-spectrum antibiotics has fueled a worrisome surge in Multidrug Resistance (MDR) among the strains of K. pneumoniae, which has significantly boosted the risk and complexity of nosocomial infection transmission in clinical settings. Consequently, this situation presents a substantial challenge to the efficacy of anti-infective treatments, making the development of new and innovative therapeutic approaches important. Bacteriophages (phages) are viruses that can infect and kill bacteria. They and their derived products are now being considered as promising alternatives or adjuncts to antimicrobial therapies for treating bacterial infections in humans, which exhibit a remarkable safety profile and precise host specificity. Numerous studies have also unequivocally demonstrated the remarkable potential of phages in effectively combating MDR K. pneumoniae infections both in vitro and in vivo. These studies have explored various approaches to K. pneumoniae phages, such as phage cocktails, phage-derived enzymes, and the synergistic utilization of phages and antibiotics. Therefore, phage therapy is old but not obsolete, particularly in light of the escalating problem of antimicrobial-resistant K. pneumoniae infections. Here, we have presented a comprehensive summary of the current knowledge on phage therapy for K. pneumoniae infections, including phage distribution, in vitro characterization of phages, in vivo investigations, and cases of clinical study. This review highlights the rapid advancements in phage therapy for K. pneumoniae, offering a promising avenue for combating this global public health threat.

Identification of beta-lactamase genes and molecular genotyping of multidrug-resistant clinical isolates of Klebsiella pneumoniae

BACKGROUND

Klebsiella pneumoniae is a clinically relevant pathogen that has raised considerable public health concerns. This study aims to determine the presence of beta-lactamase genes and perform molecular genotyping of multidrug-resistant (MDR) K. pneumoniae clinical isolates.

METHODS

Clinical isolates of MDR K. pneumoniae were collected from educational hospitals affiliated with Babol University of Medical Sciences. The isolates of K. pneumoniae were identified through standard microbial and biochemical tests. Antibiotic resistance was assessed using disk diffusion, modified Hodge test (MHT), combined disk, and polymerase chain reaction (PCR) methods. Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR was performed for molecular typing.

RESULTS

A total of 42 MDR K. pneumoniae isolates were obtained from various clinical specimens. The highest antibiotic resistance was observed for ampicillin (100%), while the lowest resistance was noted for amikacin (19.04%). The MHT indicated that 38.09% of K. pneumoniae isolates produced carbapenemase enzymes. Metallo-beta-lactamase (MBL) production was found in 54.76% of isolates. Molecular detection of beta-lactamase genes revealed the presence of blaNDM (21.42%), blaKPC (42.85%), blaTEM (76.19%), blaSHV (47.16%), and blaCTX-M (80.95%) genes. ERIC-PCR molecular typing identified seven distinct genetic patterns among the isolates.

CONCLUSIONS

This investigation demonstrates the high resistance levels of K. pneumoniae strains. The beta-lactamase genes with the highest and lowest frequencies correspond to blaCTX-M and blaNDM genes, respectively. ERIC-PCR dendrograms suggest a common origin for K. pneumoniae clinical isolates and the propagation of similar clones within hospital wards. These findings indicate that K. pneumoniae isolates are highly virulent, necessitating the development of more effective resistance-fighting techniques and gene transfer research.

CLINICAL TRIAL NUMBER

Not applicable.

Specificity and diversity of Klebsiella pneumoniae phage-encoded capsule depolymerases

Klebsiella pneumoniae is an opportunistic pathogen with significant clinical relevance. K. pneumoniae-targeting bacteriophages encode specific polysaccharide depolymerases with the ability to selectively degrade the highly varied protective capsules, allowing for access to the bacterial cell wall. Bacteriophage depolymerases have been proposed as novel antimicrobials to combat the rise of multidrug-resistant K. pneumoniae strains. These enzymes display extraordinary diversity, and are key determinants of phage host range, however with limited data available our current knowledge of their mechanisms and ability to predict their efficacy is limited. Insight into the resolved structures of Klebsiella-specific capsule depolymerases reveals varied catalytic mechanisms, with the intra-chain cleavage mechanism providing opportunities for recombinant protein engineering. A detailed comparison of the 58 characterised depolymerases hints at structural and mechanistic patterns, such as the conservation of key domains for substrate recognition and phage tethering, as well as diversity within groups of depolymerases that target the same substrate. Another way to understand depolymerase specificity is by analyzing the targeted capsule structures, as these may share similarities recognizable by bacteriophage depolymerases, leading to broader substrate specificities. Although we have only begun to explore the complexity of Klebsiella capsule depolymerases, further research is essential to thoroughly characterise these enzymes. This will be crucial for understanding their mechanisms, predicting their efficacy, and engineering optimized enzymes for therapeutic applications.

Epidemiology and molecular characterization of carbapenem-resistant Klebsiella pneumoniae isolated from neonatal intensive care units in General Hospital of Ningxia Medical University, China, 2017-2021

OBJECTIVES

This study aimed to retrospectively investigate the epidemiology and molecular characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates from neonatal intensive care units (NICU) between 2017 and 2021.

METHODS

The antibacterial susceptibility of all strains was assessed using the VITEK 2 compact system. The presence of antibiotic resistance, virulence genes, sequence types (STs), capsular (K) types, and the wzi genes was determined through polymerase chain reaction (PCR). Molecular typing was performed by pulsed-field gel electrophoresis (PFGE) using the restriction enzyme XbaI. Additionally, the virulence potential of peg344-positive strains was evaluated using the string test and mouse intraperitoneal infection models. Whole-genome sequencing was conducted on the DNB system and PacBio platforms.

RESULTS

A total of 46 CRKP isolates were collected during the study period. Out of these, 93.47% (43/46) were identified as CRKP strains belonging to the ST76-K10 type carrying blaNDM-5. It was observed that CRKP infection resulted in more severe clinical symptoms compared to CRKP colonization. Among the CRKP strains, a hypervirulent CRKP strain called KP-63, belonging to the ST23 type, was identified. This strain exhibited high mortality in the mouse infection model and was found to possess virulence genes. Genomic alignment analysis revealed a significant similarity between the virulence plasmid from KP-63 strain (pKP-63) and pK2044 from the hypervirulent K. pneumoniae strain NTUH-2044.

CONCLUSIONS

There has been a potential dissemination of ST76-K10 type CRKP carrying blaNDM-5 in the NICU at Ningxia Hospital. Neonatal CRKP infection has been found to cause more severe clinical symptoms than colonization. Furthermore, we have discovered a CR-hvKP strain of ST23 with serotype K1, which exhibits a significant resemblance in its virulent plasmid to pK2044. Therefore, it is crucial to enforce effective measures to restrict the spread and hinder the evolution of CRKP within the hospital.

Comparison of different disinfection protocols against contamination of ceramic surfaces with Klebsiella pneumoniae biofilm

Environmental contamination with Klebsiella pneumoniae biofilm can be a source of healthcare-associated infections. Disinfection with various biocidal active substances is usually the method of choice to remove contamination with biofilm. In this study we tested 13 different disinfection protocols using gaseous ozone, citric acid, and three working concentrations of benzalkonium chloride-based professional disinfecting products on 24-hour-old biofilms formed by two K. pneumoniae strains on ceramic tiles. All tested protocols significantly reduced total bacterial counts compared to control, varying from a log10 CFU reduction factor of 1.4 to 5.6. Disinfection combining two or more biocidal active substances resulted in significantly better anti-biofilm efficacy than disinfection with single substances, and the most effective combination for both strains was that of citric acid, gaseous ozone, and benzalkonium chloride. This follow up study is limited to K. pneumoniae alone, and to overcome this limitation, future studies should include more bacterial species, both Gram-positive and Gramnegative, and more samples for us to find optimal disinfection protocols, applicable in real hospital settings.

Differentiation Between Responders and Non-Responders to Antibiotic Treatment in Mice Using 18F-Fluorodeoxysorbitol/PET

PURPOSE

Bacterial infection causes significant mortality and morbidity worldwide despite the availability of antibiotics. Differentiation between responders and non-responders early on during antibiotic treatment will be informative to patients and healthcare providers. Our objective was to investigate whether PET imaging with 18F-Fluorodeoxysorbitol (18F-FDS) or 18F-FDG can be used to differentiate responders from non-responders to antibiotic treatment.

PROCEDURES

NTUH-K2044 was used for infection in Albino C57 female mice. Each mouse was inoculated intratracheally with NTUH-K2044 to induce lung infection (n = 8). For treatment studies, two bacterial doses for animal inoculation and two treatment starting times were compared to optimize treatment profiles. 18F-FDS or 8F-FDG /PET imaging was performed to monitor treatment progression.

RESULTS

Our results demonstrated that the treatment profiles for mice infected with 25 CFU hvKp and antibiotic treatment starting at 24 p.i. were not ideal due to no evidence of lung infection and lack of treatment efficacy. The optimal scheme is to use 250 CUF for infection and start antibiotic treatment at 24 h p.i. to monitor antimicrobial efficacy. 75% of the mice were classified as responders to antibiotic treatment. 25% of the mice were classified as non-responders. 18F-FDG was used to compare with 18F-FDS, but all mice showed increased lung uptake of 18F-FDG during 3-day treatments.

CONCLUSIONS

18F-FDS is a promising PET tracer to image bacterial infection. It can be used to monitor response to treatment, and differentiate responders from non-responders to antibiotic treatment, but 18F-FDG cannot, probably due to the presence of high degree of inflammation before and after treatment.

Screening and identification of phytochemicals from Acorus calamus L. to overcome NDM-1 mediated resistance in Klebsiella pneumoniae using in silico approach

Klebsiella pneumoniae is a potent human pathogen and a prevalent ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). Considerably, K. pneumoniae becomes a major clinical problem due to numerous AMR genes [extended-spectrum β-lactamase, plasmid-mediated AmpC, carbapenemases, tigecycline resistance, and New Delhi Metallo-β-lactamase-1 (NDM-1)] and can hydrolyze the majority of β-lactam antibiotics. Hence, targeting NDM-1 could be an effective approach to eradicate K. pneumoniae pathogenesis. A plethora of reports suggests that the plant compounds possess an anti-microbial activity and their utilization could be a promising strategy to develop novel antibiotics. Our study utilized the hydromethanolic leaves extract of Acorus calamus L. (AC) to target NDM-1 containing K. pneumonia using an in silico approach. At first, we determined the phytochemical composition of AC using GC-HRMS. Further, the phytoconstituents were screened against the NDM-1 (PDB ID: 3ZR9) of K. pneumoniae through molecular docking studies. Our results revealed the compounds from AC such as (2R,4S,6R,7S,8R,9S,13S)-16-hydroxy-5',7,9,13-tetramethylspiro[5-oxapentacyclo[10.8.0.02,9.04,8.013,18]icos-1(12)-ene-6,2'-oxane]-11-one (-9.5 kcal/mol), 4,4,5,8-tetramethyl-2,3-dihydrochromen-2-ol (-6.6 kcal/mol), 5-chloro-2-(2,4-dichloro phenoxy)phenol (-6.0 kcal/mol), [(3S,3aS,6R,6aS)-3-nitrooxy-2,3,3a,5,6,6a-hexahydrofuro[3,2-b]furan-6-yl] nitrate (-5.7 kcal/mol), 4-(3-hydroxyprop-1-enyl)-2-methoxyphenol (-5.6 kcal/mol), and (E)-3-(2,4-dimethoxyphenyl)prop-2-enoic acid (-5.6 kcal/mol) possess substantial docking scores against NDM-1. Therefore, our study concludes that phytochemicals of AC may inhibit NDM-1-mediated resistance in K. pneumoniae and could be an alternative therapeutic strategy for targeting NDM-1-containing K. pneumoniae.

Antimicrobial resistance, virulence genes profiles and molecular epidemiology of carbapenem-resistant Klebsiella pneumoniae strains from captive giant pandas (Ailuropoda melanoleuca)

BACKGROUND

Carbapenem-resistant Klebsiella pneumoniae (CRKP) increases the difficulty of clinical treatment of giant pandas. This study aimed to investigate the antibiotic susceptibility, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), virulence genes, and molecular epidemiology of CRKP strains isolated from giant pandas. A total of 187 nonduplicated Klebsiella pneumoniae (KP) isolates were collected from fresh feces of captive giant pandas at the Chengdu Research Base of Giant Panda Breeding. Then CRKP were isolated and identified through carbapenase Carba NP assay. Subsequently, the antimicrobial susceptibility testing and antibiotic resistance genes of CRKP isolates were studied by disk diffusion (K-B) and HT-qPCR, respectively. Then both the MGEs and virulence genes of CRKP isolates were analyzed by PCR. In addition, molecular epidemiology was analyzed among the CRKP strains using pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST).

RESULTS

Eight strains of CRKP (4.5%) were isolated and identified among the 187 KP strains, and seven of eight CRKP strains both exhibited resistance to imipenem, while one strain showed resistance to meropenem, and one demonstrated multiple resistance; eight CRKP strains carried a large amount of ARGs, among which ampC/blaDHA, blaSHV-01, blaSHV-02, tetB-01, tetB-02, tetC-01, and tetC-02 were the most abundant. The MGEs analysis revealed the presence of intI1 in all strains, while the detection rates of other MGEs varied, and strain 24 exhibited the highest diversity of MGE species. Seven virulence genes, including wabG, uge, ycf, entB, kpn, alls, and wcaG, showed positive results with different proportions across the strains. In addition, PFGE patterns indicated a high level of genetic diversity among the CRKP strains. MLST analysis classified the strains into different sequence types (STs).

CONCLUSIONS

This study highlighted the diversity of CRKP strains isolated from giant panda feces, which exhibited varying levels of antibiotic resistance along with multiple ARGs, MGEs and virulence genes present. These findings emphasized the importance of monitoring and researching antibiotic resistance within wildlife populations to protect the health status of these conservation dependent animals.

Arginine Regulates the Mucoid Phenotype of Hypervirulent Klebsiella pneumoniae

Hypervirulent Klebsiella pneumoniae is associated with severe community-acquired infections. Hypervirulent K. pneumoniae colonies typically exhibit a mucoid phenotype. K. pneumoniae mucoidy is influenced by a complex combination of environmental factors and genetic mechanisms. Mucoidy results from altered capsular polysaccharide chain length, yet the specific environmental cues regulating this phenotype and their impact on pathogenesis remain unclear. This study demonstrates that casamino acids enhance the mucoidy phenotype but do not affect total capsular polysaccharide levels. Through targeted screening of each amino acid present in casamino acids, we identified that arginine is necessary and sufficient to stimulate the mucoid phenotype without altering capsule abundance. Furthermore, arginine activates the rmpADC promoter, increasing rmpD transcript levels, which in turn modulates capsular polysaccharide chain length and diversity. The arginine regulator, ArgR, plays a pivotal role in this regulatory cascade since deleting argR decreases mucoidy and increases capsular polysaccharide chain length diversity. Additionally, the ∆argR mutant displays increased macrophage association and has a substantial competitive defect in the lungs of mice, suggesting a link between arginine-dependent gene regulation, immune evasion and in vivo fitness. We discovered that arginine-dependent regulation of mucoidy is conserved in four additional hypervirulent K. pneumoniae isolates likely via a conserved ARG binding box present in rmp promoters. Our findings support a model in which arginine activates ArgR and increases mucoidy in hypervirulent K. pneumoniae. As a result, it is possible that arginine-dependent regulation of mucoidy allows hypervirulent K. pneumoniae to adapt the cell surface across different niches. This study underscores the significance of arginine as a regulatory signal in bacterial virulence.

Integrated multi-omics identifies pathways governing interspecies interaction between A. fumigatus and K. pneumoniae

Polymicrobial co- and superinfections involving bacterial and fungal pathogens pose serious challenges for diagnosis and therapy, and are associated with elevated morbidity and mortality. However, the metabolic dynamics of bacterial-fungal interactions (BFI) and the resulting impact on disease outcome remain largely unknown. The fungus Aspergillus fumigatus and the bacterium Klebsiella pneumoniae are clinically important pathogens sharing common niches in the human body, especially in the lower respiratory tract. We have exploited an integrated multi-omics approach to unravel the complex and multifaceted processes implicated in the interspecies communication involving these pathogens in mixed biofilms. In this setting, A. fumigatus responds to the bacterial challenge by rewiring its metabolism, attenuating the translational machineries, and by connecting secondary with primary metabolism, while K. pneumoniae maintains its central metabolism and translation activity. The flexibility in the metabolism of A. fumigatus and the ability to quickly adapt to the changing microenvironment mediated by the bacteria highlight new possibilities for studying the impact of cross-communication between competing interaction partners. The data underscore the complexity governing the dynamics underlying BFI, such as pronounced metabolic changes mounted in A. fumigatus interacting with K. pneumoniae. Our findings identify candidate biomarkers potentially exploitable for improved clinical management of BFI.

Prevalence of carbapenem-resistant Enterobacterales (CRE) in Saudi Arabia: A systematic review and meta-analysis

Antimicrobial resistance is a significant public health issue. In addressing the threat of multidrug resistant bacterial infections, carbapenems have been used. The carbapenem-resistant Enterobacterales (CRE) are, however, rapidly expanding worldwide. Since the issue of CRE is also a problem in Saudi Arabia, the current meta-analysis was performed to comprehensively evaluate the resistance rates to the main carbapenem antibiotics and determine the actual prevalence of CRE in the country. Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines was followed. Different web databases including PubMed, Scopus, Web of Science, and ScienceDirect were searched for relevant records. Data were extracted, and summary estimates for resistance to carbapenems were calculated using DerSimonian-Laird method of meta-analysis and the random-effects model. From a total of 787 retrieved records, 69 studies were found fully eligible and were included in the final analyses. More than 50 % of all the studies were conducted after 2010, and the most frequently examined members of the Enterobacterales were Escherichia coli and Klebsiella pneumoniae. The pooled prevalence estimate for imipenem resistance was 6.6 % (95 % CI: 4.7-9.2), 9.1 % (95 % CI: 6.7-12.3) for meropenem, and 18.6 % (95 % CI: 11.9-27.9) for ertapenem. High heterogeneity (I2  > 97 %, p < 0.001) was observed for all the estimates. Compared to other regions of the country, there was higher resistance rates in the Al-Qassim and Al-Jouf provinces. Additionally, resistance to ertapenem was as high as 34.2 % in the most recent study period (2021-2024). Proteus spp was the most prevalent CRE (26.2 %). This review highlights an increasing rate of carbapenem resistance among Enterobacterales, emphasizing the need for collaborative efforts to implement strict infection control and prevention measures. Consistent surveillance is indispensable for safeguarding public health, guiding clinical decisions, and strengthening efforts to tackle the challenges of antibiotic resistance.

Applications of genome-scale metabolic models to the study of human diseases: A systematic review

BACKGROUND AND OBJECTIVES

Genome-scale metabolic networks (GEMs) represent a valuable modeling and computational tool in the broad field of systems biology. Their ability to integrate constraints and high-throughput biological data enables the study of intricate metabolic aspects and processes of different cell types and conditions. The past decade has witnessed an increasing number and variety of applications of GEMs for the study of human diseases, along with a huge effort aimed at the reconstruction, integration and analysis of a high number of organisms. This paper presents a systematic review of the scientific literature, to pursue several important questions about the application of constraint-based modeling in the investigation of human diseases. Hopefully, this paper will provide a useful reference for researchers interested in the application of modeling and computational tools for the investigation of metabolic-related human diseases.

METHODS

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Elsevier Scopus®, National Library of Medicine PubMed® and Clarivate Web of Science™ databases were enquired, resulting in 566 scientific articles. After applying exclusion and eligibility criteria, a total of 169 papers were selected and individually examined.

RESULTS

The reviewed papers offer a thorough and up-to-date picture of the latest modeling and computational approaches, based on genome-scale metabolic models, that can be leveraged for the investigation of a large variety of human diseases. The numerous studies have been categorized according to the clinical research area involved in the examined disease. Furthermore, the paper discusses the most typical approaches employed to derive clinically-relevant information using the computational models.

CONCLUSIONS

The number of scientific papers, utilizing GEM-based approaches for the investigation of human diseases, suggests an increasing interest in these types of approaches; hopefully, the present review will represent a useful reference for scientists interested in applying computational modeling approaches to investigate the aetiopathology of human diseases; we also hope that this work will foster the development of novel applications and methods for the discovery of clinically-relevant insights on metabolic-related diseases.

Thymol and carvacrol against Klebsiella: anti-bacterial, anti-biofilm, and synergistic activities-a systematic review

Introduction

Klebsiella poses a significant global threat due to its high antibiotic resistance rate. In recent years, researchers have been seeking alternative antimicrobial agents, leading to the introduction of natural compounds such as monoterpenes, specifically thymol and carvacrol. This review aims to illustrate the potential antimicrobial, anti-biofilm, and synergistic traits of thymol and carvacrol in combat against Klebsiella.

Methods

Searching PubMed, Scopus, and Web of Science, we reviewed available evidence on the antibacterial effects of thymol, carvacrol, or combined with other compounds against Klebsiella until May 2024. Reference checking was performed after the inclusion of studies. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), fractional inhibitory concentration (FIC), and anti-biofilm activity were gathered, and the MBC/MIC ratio was calculated to assess the bactericidal efficacy.

Results

We retrieved 38 articles out of 2,652 studies screened. The gathered data assessed the anti-microbial activity of thymol, carvacrol, and both compounds in 17, 10, and 11 studies, respectively. The mean (± standard deviation) non-weighted MIC was 475.46 μg/mL (±509.95) out of 60 MIC for thymol and 279.26 μg/mL (±434.38) out of 68 MIC for carvacrol. Thymol and carvacrol showed anti-biofilm activities in the forms of disruption, inhibition, and mass reduction of biofilms. The MBC/MIC ratio was lower than 4 in 45 out of 47 cases, showing high bactericidal efficacy. FIC values were gathered for 68 combinations of thymol and carvacrol with other compounds, and they were mostly synergistic or additive.

Conclusion

Thymol and carvacrol alone or in combination with other compounds, specifically known antibiotics, show great antimicrobial activity.

Maximally precise combinations to overcome metallo-β-lactamase-producing Klebsiella pneumoniae

Gram-negatives harboring metallo-β-lactamases (MBLs) and extended-spectrum β-lactamases (ESBLs) pose a substantial risk to the public health landscape. In ongoing efforts to combat these "superbugs," we explored the clinical combination of aztreonam and ceftazidime/avibactam together with varying dosages of polymyxin B and imipenem against Klebsiella pneumoniae (Kp CDC Nevada) in a 9-day hollow fiber infection model (HFIM). As previously reported by our group, although the base of aztreonam and ceftazidime/avibactam alone leads to 3.34 log10 fold reductions within 72 hours, addition of polymyxin B or imipenem to the base regimen caused maximal killing of 7.55 log10 and 7.4 log10 fold reduction, respectively, by the 72-hour time point. Although low-dose polymyxin B and imipenem enhanced the bactericidal activity as an adjuvant to aztreonam +ceftazidime/avibactam, regrowth to ~9 log10CFU/mL by 216 hours rendered these combinations ineffective. When aztreonam +ceftazidime/avibactam was supplemented with high-dose polymyxin B and or low-dose polymyxin B + imipenem, it resulted in effective long-term clearance of the bacterial population. Time lapse microscopy profiled the emergence of long filamentous cells in response to PBP3 binding due to aztreonam and ceftazidime. The emergence of spheroplasts via imipenem and damage to the outer membrane via polymyxin B was visualized as a mechanism of persister killing. Despite intrinsic mgrB and blaNDM-1 resistance, polymyxin B and β-lactam combinations represent a promising strategy. Future studies using an integrated molecularly precise pharmacodynamic approach are warranted to unravel the mechanistic details to propose optimal antibiotic combinations to combat untreatable, pan-drug-resistant Gram-negatives.

Epidemiology and Antibiotic Resistance Patterns of Klebsiella pneumoniae Infections Among Male Patients in a Long-Term Care Hospital in Riyadh, Saudi Arabia: A Retrospective Study

BACKGROUND

Klebsiella pneumoniae is an opportunistic pathogen commonly found in the normal flora of the gastrointestinal tract. While it typically remains benign, it can lead to severe healthcare-associated infections, particularly among immunocompromised individuals and those in long-term care settings. This study aimed to investigate the epidemiology and antibiotic resistance patterns of K. pneumoniae infections among male patients in a long-term care hospital.

METHODS

A retrospective cross-sectional study was conducted, analyzing microbial culture data from 29 male patients admitted to the male ward of a long-term care hospital in Riyadh, Saudi Arabia. The study included patients with confirmed positive cultures for K. pneumoniae. Data were collected regarding demographic information, culture sites, and antibiotic susceptibility test results. Statistical analysis was performed to identify significant associations between patient characteristics and resistance patterns, with a particular focus on the prevalence of carbapenem-resistant Enterobacterales (CRE) and the production of extended-spectrum beta-lactamases (ESBL).

RESULTS

Around 51.7% of the K. pneumoniae isolates were found to be resistant to carbapenems, while 24.1% were classified as producers of ESBL. Patients suffering from bedsores had a significantly higher prevalence of CRE infections at 37.9% compared to only 13.8% in patients without bedsores (p=0.034). The analysis also indicated that older patients (aged over 50 years) exhibited a higher prevalence of CRE infections (34.5%) compared to their younger counterparts (17.2%, p=0.069). Notably, resistance levels against antibiotics were high, with 75.9% of isolates resistant to cotrimoxazole, 65.5% to ciprofloxacin, and 62.1% to gentamicin. In contrast, imipenem and meropenem showed relatively higher susceptibility, with each antibiotic having a susceptibility rate of 34.5%.

CONCLUSION

There is a significant prevalence of multidrug-resistant K. pneumoniae infections in long-term care environments, particularly affecting older male patients and those with bedsores. These findings underscore the need for targeted infection control measures and enhanced antibiotic stewardship programs. Future research should include both genders to investigate epidemiological differences and broader resistance trends.

Maxillary herpes zoster with nasociliary nerve involvement and Klebsiella superinfection: A rare occurrence

Herpes zoster is an acute cutaneous viral disease resulting from reactivation of dormant varicella-zoster virus. The maxillary nerve is the least frequently affected branch of the trigeminal nerve. Rarely, cutaneous lesions can be secondarily infected with Klebsiella species. This report discusses a case of maxillary zoster with nasociliary nerve involvement and Klebsiella superinfection.

Advances in nucleic acid aptamer-based detection of respiratory virus and bacteria: a mini review

Respiratory pathogens infecting the human respiratory system are characterized by their diversity, high infectivity, rapid transmission, and acute onset. Traditional detection methods are time-consuming, have low sensitivity, and lack specificity, failing to meet the needs of rapid clinical diagnosis. Nucleic acid aptamers, as an emerging and innovative detection technology, offer novel solutions with high specificity, affinity, and broad target applicability, making them particularly promising for respiratory pathogen detection. This review highlights the progress in the research and application of nucleic acid aptamers for detecting respiratory pathogens, discussing their selection, application, potential in clinical diagnosis, and future development. Notably, these aptamers can significantly enhance the sensitivity and specificity of detection when combined with detection techniques such as fluorescence, colorimetry and electrochemistry. This review offers new insights into how aptamers can address the limitations of traditional diagnostic methods and advance clinical diagnostics. It also highlights key challenges and future research directions for the clinical application of nucleic acid aptamers.

The Association between Resistance and Virulence of Klebsiella pneumoniae in High-Risk Clonal Lineages ST86 and ST101

Klebsiella pneumoniae is an opportunistic pathogen known for two main pathotypes: classical K. pneumoniae (cKp), often multidrug-resistant and common in hospitals, and hypervirulent K. pneumoniae (hvKp), associated with severe community-acquired infections. The recent emergence of strains combining hypervirulence and resistance is alarming. This study investigates the distribution of sequence types (STs), resistance, and virulence factors in K. pneumoniae strains causing bloodstream and urinary tract infections in Croatia. In 2022, 200 consecutive K. pneumoniae isolates were collected from blood and urine samples across several Croatian hospitals. Whole genome sequencing was performed on 194 isolates. Within the analyzed K. pneumoniae population, the distribution of sequence types was determined with multi-locus sequence typing (MLST) and capsule loci, resistance, and virulence determinants were assessed with the bioinformatics tool Kleborate. The analysis identified 77 different STs, with ST101 (24.6%) being the most prevalent, predominantly linked to the K17 capsular type (CT), invasive device usage, high antimicrobial resistance, and low virulence scores. The highest virulence scores were recorded in ST86 isolates, which were predominantly linked to the K2 CT and included some strains with medium resistance scores. String tests were positive in 19 strains, but only four of those harbored hypermucoviscous genetic determinants. The most prevalent ST101 clone in Croatia demonstrated a diverging association between resistance and virulence. An alarming co-existence of resistance and virulence was recorded in the ST86 strains.

Transmission Dynamics and Novel Treatments of High Risk Carbapenem-Resistant Klebsiella pneumoniae: The Lens of One Health

The rise of antibiotic resistance and the dwindling antimicrobial pipeline have emerged as significant threats to public health. The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) poses a global threat, with limited options available for targeted therapy. The CRKP has experienced various changes and discoveries in recent years regarding its frequency, transmission traits, and mechanisms of resistance. In this comprehensive review, we present an in-depth analysis of the global epidemiology of K. pneumoniae, elucidate resistance mechanisms underlying its spread, explore evolutionary dynamics concerning carbapenem-resistant hypervirulent strains as well as KL64 strains of K. pneumoniae, and discuss recent therapeutic advancements and effective control strategies while providing insights into future directions. By going through up-to-date reports, we found that the ST11 KL64 CRKP subclone with high risk demonstrated significant potential for expansion and survival benefits, likely due to genetic influences. In addition, it should be noted that phage and nanoparticle treatments still pose significant risks for resistance development; hence, innovative infection prevention and control initiatives rooted in One Health principles are advocated as effective measures against K. pneumoniae transmission. In the future, further imperative research is warranted to comprehend bacterial resistance mechanisms by focusing particularly on microbiome studies' application and implementation of the One Health strategy.

Deciphering the gastrointestinal carriage of Klebsiella pneumoniae

Bacterial infections pose a significant global health threat, accounting for an estimated 7.7 million deaths. Hospital outbreaks driven by multi-drug-resistant pathogens, notably Klebsiella pneumoniae (K. pneumoniae), are of grave concern. This opportunistic pathogen causes pneumonia, urinary tract infections, and bacteremia, particularly in immunocompromised individuals. The rise of hypervirulent K. pneumoniae adds complexity, as it increasingly infects healthy individuals. Recent epidemiological data suggest that asymptomatic gastrointestinal carriage serves as a reservoir for infections in the same individual and allows for host-to-host transmission via the fecal-oral route. This review focuses on K. pneumoniae's gastrointestinal colonization, delving into epidemiological evidence, current animal models, molecular colonization mechanisms, and the protective role of the resident gut microbiota. Moreover, the review sheds light on in vivo high-throughput approaches that have been crucial for identifying K. pneumoniae factors in gut colonization. This comprehensive exploration aims to enhance our understanding of K. pneumoniae gut pathogenesis, guiding future intervention and prevention strategies.