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

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.

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).

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.

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.

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.

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.

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.

Resistance Genes and Mortality in Carbapenem-resistant Klebsiella pneumoniae Bacteremias: Effects of the COVID-19 Pandemic

Background

Emerging carbapenem-resistant Klebsiella pneumoniae (K. pneumoniae) (CRKP) bacteremias are presenting significant public health risks due to limited treatment options and increased mortality. K. pneumoniae isolates exhibit carbapenem resistance rates that vary from 25% to 50% throughout the European continent, including our country.

Aims

To assess the characteristics of CRKP bacteremia, a condition that has recently demonstrated an increasing prevalence in our center. We sought to ascertain the resistance rates of isolated strains to antibiotics other than carbapenems, identify the responsible carbapenemase genes, evaluate the efficacy of antibiotics, determine mortality rates, explore clonality among strains, and investigate the influence of the COVID-19 pandemic on all these factors.

Study Design

Retrospective observational study.

Methods

This study included patients aged 18 and older who had experienced meropenem-resistant K. pneumoniae bacteremia. Meropenem resistance was confirmed by employing the Kirby-Bauer disk diffusion method. Meropenem minimum inhibitory concentration (MIC) levels were determined using the gradient test, while colistin MIC levels were ascertained using the disk elution technique. Carbapenemase genes were evaluated via colony polymerase chain reaction (PCR), and clonality analysis was performed using the arbitrarily primed PCR technique.

Results

The study comprised 230 patients, with a mean age of 63.1 ± 15.9 years, of whom 58.7% were male. Oxacillinase-48 (OXA-48) was detected in 74.8% of the patients, New Delhi metallo-beta-lactamase (NDM) in 12.6%, OXA-48 + NDM in 7.8%, and KPC in 4.8%. The 14-day and 30-day mortality rates were 57% and 69.6%, respectively. Multivariate analysis of the 30-day mortality revealed several crucial factors, including bacteremia development in the intensive care unit, the occurrence of bacteremia during the COVID-19 pandemic, polymicrobial bacteremia, the use of indwelling intravenous catheters, a platelet count of ≤ 140,000/μl, procalcitonin levels of ≥ 6 μg/l, and a Charlson comorbidity score ≥ 3. Notably, the OXA-48 and KPC genes were upregulated significantly during the COVID-19 pandemic, while the NDM gene groups were downregulated. Additionally, both 14-day and 30-day mortality rates increased significantly.

Conclusion

In this study, the most prevalent carbapenemase gene was OXA-48; however, there has been a recent increase in KPC genes. No dominant epidemic strain was identified through clonality analysis. The clustering rate was 68% before the pandemic, increasing to 85.7% during the pandemic. The significance of infection control measures is underscored by the rise in both clustering and mortality rates during the COVID-19 pandemic.

Modeling the transmission of antibiotic-resistant Enterobacterales in the community: A systematic review

BACKGROUND

Antibiotic-resistant Enterobacterales (ARE) are a public health threat worldwide. Dissemination of these opportunistic pathogens has been largely studied in hospitals. Despite high prevalence of asymptomatic colonization in the community in some regions of the world, less is known about ARE acquisition and spread in this setting. As explaining the community ARE dynamics has not been straightforward, mathematical models can be key to explore underlying phenomena and further evaluate the impact of interventions to curb ARE circulation outside of hospitals.

METHODS

We conducted a systematic review of mathematical modeling studies focusing on the transmission of AR-E in the community, excluding models only specific to hospitals. We extracted model features (population, setting), formalism (compartmental, individual-based), biological hypotheses (transmission, infection, antibiotic impact, resistant strain specificities) and main findings. We discussed additional mechanisms to be considered, open scientific questions, and most pressing data needs.

RESULTS

We identified 18 modeling studies focusing on the human transmission of ARE in the community (n=11) or in both community and hospital (n=7). Models aimed at (i) understanding mechanisms driving resistance dynamics; (ii) identifying and quantifying transmission routes; or (iii) evaluating public health interventions to reduce resistance. To overcome the difficulty of reproducing observed ARE dynamics in the community using the classical two-strains competition model, studies proposed to include mechanisms such as within-host strain competition or a strong host population structure. Studies inferring model parameters from longitudinal carriage data were mostly based on models considering the ARE strain only. They showed differences in ARE carriage duration depending on the acquisition mode: returning travelers have a significantly shorter carriage duration than discharged hospitalized patient or healthy individuals. Interestingly, predictions across models regarding the success of public health interventions to reduce ARE rates depended on pathogens, settings, and antibiotic resistance mechanisms. For E. coli, reducing person-to-person transmission in the community had a stronger effect than reducing antibiotic use in the community. For Klebsiella pneumoniae, reducing antibiotic use in hospitals was more efficient than reducing community use.

CONCLUSIONS

This study raises the limited number of modeling studies specifically addressing the transmission of ARE in the community. It highlights the need for model development and community-based data collection especially in low- and middle-income countries to better understand acquisition routes and their relative contribution to observed ARE levels. Such modeling will be critical to correctly design and evaluate public health interventions to control ARE transmission in the community and further reduce the associated infection burden.

Comparison of Mutant Prevention Concentrations of Fluoroquinolones Against ESBL-Positive and ESBL-Negative Klebsiella pneumoniae Isolates from Orthopedic Patients

The majority of Klebsiella pneumonia isolates possess the extended-spectrum beta-lactamase (ESBL) enzymes. Therefore, K. pneumoniae can easily develop drug resistance. How to effectively overcome the problem of drug resistance in K. pneumoniae is still a research hotspot. This study aimed to compare the mutant prevention concentration (MPC) of ESBL-positive and ESBL-negative K. pneumoniae isolated from orthopedic patients, which may provide a basis for the effective use of drugs to control the enrichment of resistance mutants of K. pneumoniae. The MPC90 values of 55 isolates of ESBL-positive K. pneumoniae against 4 fluoroquinolones were 32 µg/mL for levofloxacin and gatifloxacin, 16 µg/mL for ciprofloxacin, and 4 µg/mL for gemifloxacin. The selection index value was 8 for levofloxacin and ciprofloxacin and 2 for gemifloxacin and gatifloxacin, respectively. For ESBL-negative K. pneumoniae isolates, the MPC90 values were 16 µg/mL for levofloxacin and ciprofloxacin, 4 µg/mL for gemifloxacin, and 32 µg/mL for gatifloxacin. The selection index value was 8 for levofloxacin and ciprofloxacin, 2 for gemifloxacin, and 4 for gatifloxacin. For the ESBL-positive K. pneumoniae, the %T>MIC90 order was gemifloxacin > levofloxacin > ciprofloxacin > gatifloxacin. For the ESBL-negative K. pneumoniae, the %T>MIC90 order was levofloxacin > gemifloxacin > ciprofloxacin > gatifloxacin. The mutant-preventing ability of gatifloxacin and gemifloxacin was the strongest among the 4 fluoroquinolones. So gemifloxacin may be the first choice of drug to treat K. pneumoniae infection.

Essential oils as capsule disruptors: enhancing antibiotic efficacy against multidrug-resistant Klebsiella pneumoniae

Background

Multidrug-resistant Klebsiella pneumoniae (MDR-KP) poses a significant global health threat due to its involvement in severe infections and high mortality rates. The emergence of MDR strains necessitates the exploration of alternative therapeutic strategies.

Methods

K. pneumoniae isolates were obtained from human and animal sources. Antibacterial susceptibility testing was performed, followed by the evaluation of essential oil activity through inhibition zone, MIC, and MBC determinations. Checkerboard assays were conducted to assess synergistic effects with amikacin. Gene expression analysis and transmission electron microscopy were employed to elucidate the mechanisms of action. Molecular docking studies were performed to identify potential binding targets of bioactive compounds.

Results

Klebsiella pneumoniae was isolated from 25 of the100 samples examined, representing a prevalence rate of 25%. All isolates were found to be multidrug-resistant. Tea tree and thyme essential oils exhibited potent antibacterial activity and synergistic effects with amikacin. Notably, these combinations significantly downregulated the expression of key capsule virulence genes (wcaG, rmpA, magA, uge, and wabG), suggesting a novel mechanism for enhancing amikacin efficacy. Transmission electron microscopy revealed disrupted cell integrity in MDR-KP cells treated with the combinations. Molecular docking analysis identified Terpinen-4-ol, Farnesol, 1,4-Dihydroxy-p-menth-2-ene, and 7-Oxabicyclo [4.1.0] heptane as potential bioactive compounds responsible for the observed effects.

Conclusion

By effectively combating MDR-KP, this research holds promise for reducing antibiotic resistance, improving treatment outcomes, and ultimately enhancing potential care.

Resistance Pattern of Klebsiella pneumoniae in Aseer Region, Saudi Arabia: A Ten-Year Hospital-Based Study

Background and Objectives: The frequency of multidrug-resistant Klebsiella pneumoniae (MDRKP) has dramatically increased worldwide in recent decades, posing an urgent threat to public health. The aim of this study was to assess the extent of K. pneumoniae in the Aseer region and explore the corresponding antimicrobial resistance profile over the last ten years. Materials and Methods: A record-based retrospective study was conducted in a tertiary hospital during the period of 2013 to 2022. The study targeted laboratory samples taken from patients admitted to the hospital and sent for K. pneumoniae culturing. We included only samples taken from the patient and confirmed by the lab. Data were extracted using a pre-structured data extraction sheet to avoid data-collection bias and confirm the inter-rater precision. Statistical Package for Social Sciences (SPSS) version 26 was employed for statistical analysis. All relationships were tested using Pearson X2 test for categorical data or chi-square for linear trend for resistance rate over years. Results: We obtained 3921 samples of isolated K. pneumoniae out of 28,420 bacterial samples. The isolation rate began at 11.3% in 2013, decreased to 6.1% in 2016, and then increased to a peak of 16.3% in 2021, before slightly decreasing to 12.8% in 2022. In total, 23.7% of K. pneumoniae samples were identified in urine samples, 19% in sputum samples, 14% in wound samples, and 11.7% in blood samples. The overall antibiotic resistance rate of K. pneumoniae from 2013 to 2022 showed a significant increase, particularly during 2020 and 2021, before decreasing again in 2022. The resistance rate decreased from 22.2% in 2013 to 18.6% in 2016 and increased to 54.6% and 56.4% during 2020 and 2021, respectively (p = 0.039). Conclusions: We observed a significant shift in K. pneumoniae resistance for some antibiotics during the study period, highlighting the urgent need for enhanced antimicrobial stewardship and infection-control measures.

Exploring Ventilator-Associated Pneumonia: Microbial Clues and Biomarker Insights from a Retrospective Study

Background and Objectives: Ventilator-associated pneumonia (VAP) is a common complication in critically ill patients receiving mechanical ventilation. The incidence rates of VAP vary, and it poses significant challenges due to microbial resistance and the potential for adverse outcomes. This study aims to explore the microbial profile of VAP and evaluate the utility of biomarkers and illness severity scores in predicting survival. Materials and Methods: A retrospective cohort study was conducted involving 130 patients diagnosed with VAP. Microbial analysis of bronchoalveolar lavage (BAL) fluid, as well as measurements of C-reactive protein (CRP) and procalcitonin (PCT) levels, were performed. Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were calculated to assess illness severity. Statistical analyses were conducted to determine correlations and associations. Results: The study revealed that Klebsiella pneumoniae (K. pneumoniae) (50.7%) and Pseudomonas aeruginosa (P. aeruginosa) (27.69%) were the most identified microorganisms in VAP cases. SOFA (p-value < 0.0001) and APACHE II (p-value < 0.0001) scores were effective in assessing the severity of illness and predicting mortality in VAP patients. Additionally, our investigation highlighted the prognostic potential of CRP levels (odds ratio [OR]: 0.980, 95% confidence interval [CI] 0.968 to 0.992, p = 0.001). Elevated levels of CRP were associated with reduced survival probabilities in VAP patients. Conclusion: This study highlights the microbial profile of VAP and the importance of biomarkers and illness severity scores in predicting survival. Conclusions: The findings emphasize the need for appropriate management strategies to combat microbial resistance and improve outcomes in VAP patients.

High prevalence of carbapenem-resistant Enterobacterales (CRE) in human samples from Nigeria: A systematic review and meta-analysis

Objectives

The rise in Carbapenem-resistant Enterobacterales (CRE) is perturbing. To curb the menace of CRE, a comprehensive understanding of its prevalence and epidemiology is crucial. As varying reports abound, the true prevalence of CRE in Nigeria remains unknown. Here, we conducted a systematic review and meta-analysis following standard guidelines to assess the situation of CRE in Nigeria.

Methods

We searched electronic databases including Pubmed, ScienceDirect, Scopus, Web of Science, and Google Scholar for articles providing information on CRE in Nigeria. The data gathered were analyzed using OpenMeta Analyst and Comprehensive Meta-Analysis software. The random-effect model was employed to calculate pooled resistance to carbapenem antibiotics.

Results

From 321 retrieved records, 57 were finally included. The studies were predominantly from the South-West region (n = 19). Escherichia coli and Klebsiella pneumoniae were the most frequently tested Enterobacterales among the included studies. The pooled prevalence estimate for imipenem resistance among CRE was 11.2 % (95 % CI: 7.9-15.7). Meropenem resistance had an estimate of 13.5 % (95 % CI: 9.1-19.6), whereas ertapenem and doripenem were estimated at 17.0 % (95 % CI: 9.9-27.7) and 37.9 % (95 % CI: 15.0-67.8), respectively. High heterogeneity (I 2 >85 %, p < 0.001) was observed for the estimates. The highest resistance rate to imipenem (28.4 %), meropenem (37.2 %) and ertapenem (46.5 %) were observed for the South-South region. Based on specific CRE genera, Morganella sp. was the most resistant (37.0 %) while Escherichia sp. was the least (9.4 %). Our analyses also revealed a progressive increase in resistance to carbapenem antibiotics over the years.

Conclusion

This study highlights carbapenem resistance as a concern in Africa's most populous nation, underscoring the need for proactive measures to address and mitigate the threat of CRE.

Characterization of mAbs against Klebsiella pneumoniae type 3 fimbriae isolated in a target-independent phage display campaign

We used phage display, antibody engineering, and high-throughput assays to identify antibody-accessible targets of Klebsiella pneumoniae. We report the discovery of monoclonal antibodies (mAbs) binding to type 3 fimbrial proteins, including MrkA. We found that anti-MrkA mAbs were cross-reactive to a diverse panel of K. pneumoniae clinical isolates, representing different O-serotypes. mAbs binding to MrkA have previously been described and have been shown to provide prophylactic protection, although only modest protection when dosed therapeutically in vivo in a murine lung infection model. Here, we used a combination of binding and opsonophagocytic killing studies using a high-content imaging platform to provide a possible explanation for the modest therapeutic efficacy in vivo reported in that model. Our work shows that expression of K. pneumoniae type 3 fimbriae in in vitro culture is not homogenous within a bacterial population. Instead, sub-populations of bacteria that do, and do not, express type 3 fimbriae exist. In a high-content opsonophagocytic killing assay, we showed that MrkA-targeting antibodies initially promote killing by macrophages; however, over time, this effect is diminished. We hypothesize the reason for this is that bacteria not expressing MrkA can evade opsonophagocytosis. Our data support the fact that MrkA is a conserved, immunodominant protein that is antibody accessible on the surface of K. pneumoniae and suggest that additional studies should evaluate the potential of using anti-MrkA antibodies in different stages of K. pneumoniae infection (different sites in the body) as well as against K. pneumoniae biofilms in the body during infection and associated with medical devices.IMPORTANCEThere is an unmet, urgent need for the development of novel antimicrobial therapies for the treatment of Klebsiella pneumoniae infections. We describe the use of phage display, antibody engineering, and high-throughput assays to identify antibody-accessible targets of K. pneumoniae. We discovered monoclonal antibodies (mAbs) binding to the type 3 fimbrial protein MrkA. The anti-MrkA mAbs were found to be highly cross-reactive, binding to all K. pneumoniae strains tested from a diverse panel of clinical isolates, and were active in an opsonophagocytic killing assay at pM concentrations. MrkA is important for biofilm formation; thus, our data support further exploration of the use of anti-MrkA antibodies for preventing and/or controlling K. pneumoniae in biofilms and during infection.

Hypervirulent Klebsiella pneumoniae-related bacteremia in intensive care unit: A retrospective cohort study

INTRODUCTION

Hypervirulent Klebsiella pneumoniae (hvKP) bloodstream infections (BSI) have rarely been reported in critically ill patients.

METHODS

We conducted a retrospective study of KP-BSI between January 2016 and December 2020 in an adult medical intensive care unit (ICU) of our tertiary care hospital. Hypervirulent phenotype was defined by the detection of both rmpA and iutA.

RESULTS

Seventy patients diagnosed with K. pneumonia BSI were included, of whom 9 (13 %) had hvKP infection. Pneumonia accounted for 56 % of hvKP-BSI and for 28 % of those with cKP. Fifty-six percent of patients with hvKP-BSI were homeless, versus 2 % of those with cKP-BSI (p < 0.001). The 30-day mortality rate reached 44 % for hvKP-BSI and 34 % for cKP-BSI (p = 0.7) and did not appear related to the hypervirulent phenotype in multivariable analysis.

DISCUSSION

We here evidenced a new clinical entity of hvKP-BSI associated with pulmonary infection in homeless patients, which exhibits high mortality.

Nonendemic rhinoscleroma: An unusual manifestation of the trachea

Objectives

Rhinoscleroma is classically described as a chronic granulomatous disease caused by Klebsiella rhinoscleromatis which primarily affects the nose and nasopharynx. When present, tracheal manifestations will be seen late in the disease course rather than on initial presentation. We describe a rare case of nonendemic rhinoscleroma that presented with tracheal lesions as an initial manifestation of disease.

Methods

Case report and literature review.

Results

An 88-year-old male presented with longstanding dysphonia. Flexible laryngoscopy demonstrated a septal perforation and diffuse glottic lesions. CT neck demonstrated a nonobstructive polypoid tracheal lesion and mucosal thickening of the paranasal sinuses. Biopsy confirmed an atypical lympho-histiocytic proliferation and microorganisms within macrophages on Grocott methenamine silver and Steiner stains consistent with rhinoscleroma. He was referred for rheumatology and pulmonology consultation.

Conclusion

Systemic diseases rarely affect the trachea, and even less frequently is a tracheal lesion identified as the initial manifestation of disease. The most common systemic diseases that affect the trachea include relapsing polychondritis, granulomatosis with polyangiitis, amyloidosis, and inflammatory bowel disease. The literature surrounding nasolaryngotracheal rhinoscleroma is limited, especially in nonendemic areas. It is necessary to include unusual etiologies of airway lesions in the differential diagnosis, which warrants comprehensive airway evaluation including biopsy.

Level of Evidence

4.

Gas Chromatography-Ion Mobility Spectrometry Reveals Acetoin as a Biomarker for Carbapenemase-Producing Klebsiella pneumoniae

BACKGROUND This study aimed to detect the volatile organic compound (VOC), 3-hydroxy-2-butanone (acetoin) using gas chromatography-ion mobility spectrometry (GC-IMS) in antimicrobial-resistant Klebsiella pneumoniae (K. pneumoniae) carbapenemase (KPC)-producing bacteria. MATERIAL AND METHODS Using stromal fluid of blood culture bottles (BacT/ALERT® SA) as the medium, 3-hydroxy-2-butanone (acetoin) released by K. pneumoniae during growth was detected using GC-IMS. The impact of imipenem (IPM) and carbapenemase inhibitors [avibactam sodium or pyridine-2,6-dicarboxylic acid (DPA)] on the emission of 3-hydroxy-2-butanone (acetoin) from various carbapenemase-producing K. pneumoniae was further investigated. Subsequently, VOCal software was used to generate a pseudo-3D plot of 3-hydroxy-2-butanone (acetoin), and the relative peak volumes were exported for data analysis. Standard strains served as references, and the findings were validated with clinical isolates. RESULTS The pattern of temporal changes in the 3-hydroxy-2-butanone (acetoin) release from K. pneumoniae in the absence of IPM was consistent with the growth curve. After the IPM addition, carbapenemase-positive strains released significantly higher contents of 3-hydroxy-2-butanone (acetoin) than carbapenemase-negative strains at the late exponential growth phase (T2). Notably, adding avibactam sodium significantly decreased the 3-hydroxy-2-butanone (acetoin) content released from the class A carbapenemase-producing strains as compared to the absence of the carbapenemase inhibitor. Conversely, adding DPA significantly decreased the 3-hydroxy-2-butanone (acetoin) content released from the class B carbapenemase-producing strains (both standard and clinical strains, all P<0.05). CONCLUSIONS This study demonstrated the potential of 3-hydroxy-2-butanone (acetoin) as a VOC biomarker for detecting carbapenemase-producing K. pneumoniae, as revealed by GC-IMS analysis.

Enhancing acute inflammatory and sepsis treatment: superiority of membrane receptor blockade

Conditions such as acute pancreatitis, ulcerative colitis, delayed graft function and infections caused by a variety of microorganisms, including gram-positive and gram-negative organisms, increase the risk of sepsis and therefore mortality. Immune dysfunction is a characterization of sepsis, so timely and effective treatment strategies are needed. The conventional approaches, such as antibiotic-based treatments, face challenges such as antibiotic resistance, and cytokine-based treatments have shown limited efficacy. To address these limitations, a novel approach focusing on membrane receptors, the initiators of the inflammatory cascade, is proposed. Membrane receptors such as Toll-like receptors, interleukin-1 receptor, endothelial protein C receptor, μ-opioid receptor, triggering receptor expressed on myeloid cells 1, and G-protein coupled receptors play pivotal roles in the inflammatory response, offering opportunities for rapid regulation. Various membrane receptor blockade strategies have demonstrated efficacy in both preclinical and clinical studies. These membrane receptor blockades act as early stage inflammation modulators, providing faster responses compared to conventional therapies. Importantly, these blockers exhibit immunomodulatory capabilities without inducing complete immunosuppression. Finally, this review underscores the critical need for early intervention in acute inflammatory and infectious diseases, particularly those posing a risk of progressing to sepsis. And, exploring membrane receptor blockade as an adjunctive treatment for acute inflammatory and infectious diseases presents a promising avenue. These novel approaches, when combined with antibiotics, have the potential to enhance patient outcomes, particularly in conditions prone to sepsis, while minimizing risks associated with antibiotic resistance and immune suppression.

A New Casjensviridae Bacteriophage Isolated from Hospital Sewage for Inactivation of Biofilms of Carbapenem Resistant Klebsiella pneumoniae Clinical Isolates

Klebsiella pneumoniae, a member of the ESKAPE pathogen group, is a prominent cause of hospital-acquired infections. The WHO has recognized carbapenem-resistant K. pneumoniae as a critical-one priority pathogen. These resilient superbugs have the ability to form biofilms and present a significant global threat. In the present study, we isolated and characterized a bacteriophage SAKp02, from hospital sewage, infectious to carbapenem-resistant K. pneumoniae patient isolates. SAKp02 could infect 43 of 72 clinical isolates, indicating a broad host spectrum. Whole genome analysis classified SAKp02 within the family Casjensviridae, with a 59,343 bp genome encoding 82 ORFs. Comparative genomic analysis revealed significant differences between SAKp02 and its closest viruses, indicating a distinct genetic makeup positioning it as a novel phage strain within the lineage. The SAKp02 genome comprises bacteriolytic enzymes, including holin, endolysin, and phage depolymerase, crucial for bacterial lysis and biofilm disruption. It reduced biofilm biomass by over threefold compared to the control and eradicated 99% of viable cells within a 4 h treatment period. Scanning electron microscopy corroborated the ability of the phage to dismantle biofilm matrices and lyse bacterial cells. Safe and effective treatments are warranted, and hence, the fully characterized lytic phages with therapeutic potential against drug-resistant clinical isolates of bacteria are needed. Our study is the first to report the antibacterial and antibiofilm activity of Casjensviridae phages, and our discovery of a novel K. pneumoniae phage broadens the arsenal against the bacteria.

Klebsiella pneumoniae-infected hemorrhagic ulcerative infantile hemangioma: A rare complication

Key Clinical Message

Infections in infantile hemangiomas (IHs) are generally limited, and only few cases have been reported. The rapid expansion of an ulcerated IH should raise concern for possible complications to monitor and provide immediate therapeutic interventions. This case highlights the importance of prompt treatment in large segmental IHs to prevent ulceration and related complications, including bleeding and superinfection.

Abstract

IH is a benign tumor proliferating during early infancy. While many IHs spontaneously resolve, complications like ulceration, bleeding, and potential damage to vital organs can occur, leading to pain, infection, and scarring. A 6-month-old girl with a previously treated IH on her left leg developed a Klebsiella-infected ulcer at the site. The ulcer resulted from non-standard treatments used before admission. Upon hospitalization, she was initially treated with cefepime and propranolol, but a week later, the wound culture revealed Klebsiella pneumoniae, prompting a switch to piperacillin/tazobactam. After successfully managing the infection and bleeding, the child was discharged in good condition with orders to continue treatment with propranolol for at least a year. This case highlights the potential of IHs to become infected even with uncommon germs such as Klebsiella and the importance of receiving appropriate medical care to prevent further complications.

Study of the Epidemiological and Mechanistic Differences Between Carbapenem-Resistant Klebsiella pneumoniae Infections in Children and Adults

Background

The emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) has garnered international concern due to its significant antibiotic resistance. Notably, children exhibit distinct resistance mechanisms compared to adults, necessitating a differential approach to antibiotic selection. A thorough analysis of CRKP's epidemiology and drug resistance mechanisms is essential for establishing a robust foundation for clinical anti-infection strategies and precise prevention and control measures.

Methods

This study involved the collection of 31 non-repetitive strains from pediatric and adult patients at a tertiary hospital in China, spanning from July 2016 to July 2022, testing for resistance genes, antimicrobial susceptibility, and homology analysis.

Results

Infants (0-1 year) were the largest pediatric CRKP group, with 61.3% of cases. The neonatal intensive care unit (NICU) and pediatrics were the main departments affected. Adults with CRKP had a mean age of 67 years, with the highest prevalence in neurology and emergency ICU. Antimicrobial susceptibility testing revealed that adult CRKP strains exhibited higher resistance to amikacin, ciprofloxacin, cotrimoxazole, and aztreonam compared to pediatric strains. Conversely, pediatric strains showed a higher rate of resistance to ceftazidime/avibactam. The predominant resistance genes identified were bla NDM-5 in children (58.1%) and bla KPC-2 in adults (87.1%), with over 93% of both groups testing positive for extended-spectrum beta-lactamase (ESBL) genes. Multilocus Sequence Typing (MLST) indicated ST2735 and ST11 as the predominant types in children and adults, respectively. Pulsed-field gel electrophoresis (PFGE) identified clonal transmission patterns of ST11 bla KPC-2 and ST15 bla OXA-232 across both age groups. Notably, this study reports the first instance of ST1114-type CRKP co-producing bla NDM-5 and bla OXA-181 in the NICU.

Conclusion

This study reveals distinct resistance mechanisms and epidemiology in CRKP from children and adults. The identified clonal transmission patterns emphasize the need for improved infection control to prevent the spread of resistant strains.

Occurrence of carbapenem-resistant hypervirulent Klebsiella pneumoniae in oysters in Egypt: a significant public health issue

BACKGROUND

The global dissemination of critical-priority carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp) via food sources represents a significant public health concern. Epidemiological data on CR-hvKp in oysters in Egypt is limited. This study aimed to investigate the potential role of oysters sold in Egypt as a source for carbapenem-resistant K. pneumoniae (CRKP), hypervirulent K. pneumoniae (hvKp), and CR-hvKp and assess associated zoonotic risks.

METHODS

A sample of 330 fresh oysters was randomly purchased from various retail fish markets in Egypt and divided into 33 pools. Bacteriological examination and the identification of Klebsiella pneumoniae were performed. Carbapenem resistance in K. pneumoniae isolates was determined by phenotypic and molecular methods. Additionally, the presence of hypervirulent K. pneumoniae was identified based on virulence gene markers (peg-344, rmpA, rmpA2, iucA, and iroB), followed by a string test. The clustering of CR-hvKp strains was carried out using R with the pheatmap package.

RESULTS

The overall prevalence of K. pneumoniae was 48.5% (16 out of 33), with 13 isolates displaying carbapenem resistance, one intermediate resistance, and two sensitive. Both carbapenem-resistant K. pneumoniae and carbapenem-intermediate-resistant K. pneumoniae strains exhibited carbapenemase production, predominantly linked to the blaVIM gene (68.8%). HvKp strains were identified at a rate of 62.5% (10/16); notably, peg-344 was the most prevalent gene. Significantly, 10 of the 13 CRKP isolates possessed hypervirulence genes, contributing to the emergence of CR-hvKp. Moreover, cluster analysis revealed the clustering of two CR-hvKp isolates from the same retail fish market.

CONCLUSION

This study provides the first insight into the emergence of CR-hvKp among oysters in Egypt. It underscores the potential role of oysters as a source for disseminating CR-hvKp within aquatic ecosystems, presenting a possible threat to public health.

Klebsiella pneumoniae alters zebrafish circadian rhythm via inflammatory pathways and is dependent on light cues

Klebsiella pneumoniae is an opportunistic pathogen causing severe infections. The circadian rhythm is the internal rhythm mechanism of an organism and plays an important role in coping with changes in the 24-h circadian rhythm. Disruption of the circadian rhythm can lead to immune, behavioral, mental, and other related disorders. Whether K. pneumoniae can disrupt the circadian rhythm after infection remains unclear. Here, we examined the effects of K. pneumoniae NTUH-K2044 infection on biological rhythm and inflammation in zebrafish using behavioral assays, quantitative real-time reverse transcription PCR, neutrophil and macrophage transgenic fish, and drug treatment. The results showed that K. pneumoniae infection decreased the motor activity of zebrafish and reduced the circadian rhythm amplitude, phase, and period. The expression of core circadian rhythm-associated genes increased under light-dark conditions, whereas they were downregulated under continuous darkness. Analysis of Klebsiella pneumoniae-mediated inflammation using Tg(mpx:EGFP) and Tg(mpeg:EGFP) transgenic zebrafish, expressing fluorescent neutrophils and macrophages, respectively, showed increased induction of inflammatory cells, upregulated expression of inflammatory factor genes, and stronger inflammatory responses under light-dark conditions. These effects were reversed by the anti-inflammatory drug G6PDi-1, and the expression of clock genes following K. pneumoniae treatment was disrupted. We determined the relationship among K. pneumoniae, inflammation, and the circadian rhythm, providing a theoretical reference for studying circadian rhythm disorders caused by inflammation.

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.

Impacts of environmental factors on the aetiological diagnosis and disease severity of community-acquired pneumonia in China: a multicentre, hospital-based, observational study

Environmental exposures are known to be associated with pathogen transmission and immune impairment, but the association of exposures with aetiology and severity of community-acquired pneumonia (CAP) are unclear. A retrospective observational study was conducted at nine hospitals in eight provinces in China from 2014 to 2019. CAP patients were recruited according to inclusion criteria, and respiratory samples were screened for 33 respiratory pathogens using molecular test methods. Sociodemographic, environmental and clinical factors were used to analyze the association with pathogen detection and disease severity by logistic regression models combined with distributed lag nonlinear models. A total of 3323 CAP patients were included, with 709 (21.3%) having severe illness. 2064 (62.1%) patients were positive for at least one pathogen. More severe patients were found in positive group. After adjusting for confounders, particulate matter (PM) 2.5 and 8-h ozone (O3-8h) were significant association at specific lag periods with detection of influenza viruses and Klebsiella pneumoniae respectively. PM10 and carbon monoxide (CO) showed cumulative effect with severe CAP. Pollutants exposures, especially PM, O3-8h, and CO should be considered in pathogen detection and severity of CAP to improve the clinical aetiological and disease severity diagnosis.

Medical Device-Associated Biofilm Infections and Multidrug-Resistant Pathogens

Medical devices such as venous catheters (VCs) and urinary catheters (UCs) are widely used in the hospital setting. However, the implantation of these devices is often accompanied by complications. About 60 to 70% of nosocomial infections (NIs) are linked to biofilms. The main complication is the ability of microorganisms to adhere to surfaces and form biofilms which protect them and help them to persist in the host. Indeed, by crossing the skin barrier, the insertion of VC inevitably allows skin flora or accidental environmental contaminants to access the underlying tissues and cause fatal complications like bloodstream infections (BSIs). In fact, 80,000 central venous catheters-BSIs (CVC-BSIs)-mainly occur in intensive care units (ICUs) with a death rate of 12 to 25%. Similarly, catheter-associated urinary tract infections (CA-UTIs) are the most commonlyhospital-acquired infections (HAIs) worldwide.These infections represent up to 40% of NIs.In this review, we present a summary of biofilm formation steps. We provide an overview of two main and important infections in clinical settings linked to medical devices, namely the catheter-asociated bloodstream infections (CA-BSIs) and catheter-associated urinary tract infections (CA-UTIs), and highlight also the most multidrug resistant bacteria implicated in these infections. Furthermore, we draw attention toseveral useful prevention strategies, and advanced antimicrobial and antifouling approaches developed to reduce bacterial colonization on catheter surfaces and the incidence of the catheter-related infections.