Clinical and microbiological characteristics and occurrence of Klebsiella pneumoniae infection in Japan

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.

Clinical Characteristics of Uncomplicated Acute Pyelonephritis Caused by Escherichia coli and Klebsiella pneumoniae

INTRODUCTION

This study compared the clinical characteristics and antimicrobial susceptibility of uncomplicated acute pyelonephritis (APN) caused by Escherichia coli and Klebsiella pneumoniae.

METHODS

We retrospectively reviewed the medical records of patients with uncomplicated APNs caused by E. coli and K. pneumoniae admitted to Keimyung University Dongsan Hospital between February 2014 and December 2021.

RESULTS

We enrolled 497 patients (372 with E. coli infection, 125 with K. pneumoniae infection). Male, healthcare-associated infection, solid tumors, liver cirrhosis, chronic renal disease, solid organ transplantation, and antibiotic usage within the last 3 months were more strongly associated with K. pneumoniae uncomplicated APNs than with E. coli. Bacteremia and fever occurred more frequently in E. coli uncomplicated APNs. Antimicrobial resistance rates to piperacillin/tazobactam and carbapenem were higher in K. pneumoniae. Antimicrobial resistance rates to aztreonam and ciprofloxacin were lower in K. pneumoniae. Thirty-day mortality was more observed in K. pneumoniae group in univariate analysis, but this difference was not observed after adjustment. Male sex, ultimately fatal disease in McCabe, and prior antibiotic use within 3 months were more associated with K. pneumoniae.

CONCLUSIONS

Male, underlying diseases, and prior antibiotic use was more associated with K. pneumoniae. Further study will be needed that microbiome of each situation and the related with the distribution of the strains.

Changes of microbiota level in urinary tract infections: A meta-analysis

No consensus has been reached on the dysbiosis signs of microbiota in patients with urinary tract infections (UTIs). This meta-analysis aimed to verify the relationship between microbiota levels and UTIs. PubMed, Web of Science, and Embase databases were retrieved for related articles published from inception until October 20, 2021. The standardized mean difference (SMD) and its related 95% confidence intervals (CIs) of the microbiota diversity and abundance were pooled under a random-effects model. Twelve studies were included in this meta-analysis. The pooled analysis revealed that the microbiota diversity was lower in patients with UTIs than in healthy individuals (SMD = -0.655, 95% CI = -1.290, -0.021, I ² = 81.0%, P = 0.043). The abundance of specific bacteria was higher in UTI subjects compared with healthy control individuals (SMD = 0.41, 95% CI = 0.07-0.74, P = 0.017), especially in North America patients with UTIs. Similar results were also found in studies with the total sample size being greater than 30. Importantly, Escherichia coli levels were increased in patients with UTI, whereas Lactobacillus levels decreased. E. coli and Lactobacilli have huge prospects as potential microbiota markers in the treatment of UTIs.

Antimicrobial Resistance Pattern, Pathogenicity and Molecular Properties of Hypervirulent Klebsiella pneumonia (hvKp) among Hospital-Acquired Infections in the Intensive Care Unit (ICU)

Hypervirulent Klebsiella pneumoniae (hvKp) is a new emerging variant of K. pneumoniae that is increasingly reported worldwide. The variant hvKp is known to cause severe invasive community-acquired infections such as metastatic meningitis, pyogenic liver abscesses (PLA) and endophthalmitis, but its role in hospital-acquired infections (HAIs) is little known. The aim of this study was to evaluate the prevalence of hvKp among hospital-acquired (HA) K. pneumoniae infections in the intensive care unit (ICU) and to compare between hvKp and classical K. pneumoniae (cKP) regarding antimicrobial resistance pattern, virulence and molecular characteristics. The study was cross-sectional and included 120 ICU patients suffering from HA K. pneumoniae infections between January and September 2022. K. pneumoniae isolates were subjected to antimicrobial susceptibility testing and detection of extended-spectrum-β-lactamase (ESBL) production by the Phoenix 100 automated microbiology system, string test, biofilm formation, serum resistance assay, and detection of virulence-associated genes (rmpA, rmpA2, magA, iucA) and capsular serotype-specific genes (K1, K2, K5, K20, K57) by polymerase chain reaction (PCR). Of 120 K. pneumoniae isolates, 19 (15.8%) were hvKp. The hypermucoviscous phenotype was more significantly detected in the hvKp group than in the cKP group (100% vs. 7.9%, p ≤ 0.001). The rate of resistance to different antimicrobial agents was significantly higher in the cKP group than that in the hvKp group. Fifty-three strains were identified as ESBL-producing strains, which was more frequent in the cKP group than in the hvKp group (48/101 [47.5%] vs. 5/19 [26.3%], respectively, p ≤ 0.001). The hvKP isolates were highly associated with moderate and strong biofilm formation than cKP isolates (p = 0.018 and p = 0.043 respectively). Moreover, the hvKP isolates were highly associated with intermediate sensitivity and re sistance to serum in the serum resistance assay (p = 0.043 and p = 0.016 respectively). K1, K2, rmpA, rmpA2, magA and iucA genes were significantly associated with hvKp (p ≤ 0.001, 0.004, <0.001, <0.001, 0.037 and <0.001, respectively). However, K5, K20 and K57 were not associated with hvKp. The hvKp strains have emerged as a new threat to ICU patients because of their ability to cause more severe and life-threatening infections than cKP. The string test alone as a laboratory test for screening of hvKp has become insufficient. Recently, hvKp was defined as hypermucoviscous- and aerobactin-positive. It is important to improve the awareness towards the diagnosis and management of hvKp infections.

Occurrence and Genomic Characteristics of Hypervirulent Klebsiella pneumoniae in a Tertiary Care Hospital, Eastern India

Purpose

This study was conducted to find out the occurrence of hypervirulent Klebsiella pneumoniae (hvKP) isolates from different clinical specimens in a tertiary care hospital of eastern India and investigate the distribution of virulence factors, capsular serotypes and antibiogram profile. The distribution of carbapenemase-encoding genes in convergent (hvKP and carbapenem-resistant) isolates was also studied.

Materials and methods

A total of 1004 K. pneumoniae isolates were obtained from different clinical specimens from August 2019 to June 2021 and hvKP isolates were identified using the string test. Genes of capsular serotypes K1, K2, K5, K20, K54 and K57, virulence-associated genes, rmpA, rmpA2, mrkD, allS, iroN, iutA, iuc, kfuB and ybtS, and carbapenemase-encoding genes, NDM-1, OXA-48, OXA-181, and KPC, were evaluated by polymerase chain reaction. Antimicrobial susceptibility was determined primarily by the VITEK-2 Compact automated platform (bioMérieux, Marcy-l'Étoile, France) and supplemented by disc-diffusion/EzyMIC (HiMedia, Mumbai, India) wherever needed.

Results

Out of 1004 isolates, 33 (3.3%) were hvKP. Most frequent capsular serotype was K2 in 11 (33.3%). Amongst virulence genes, mrkD, iutA and kfuB were detected most frequently in 93.9%, 84.8% and 63.6% isolates respectively. Classical Klebsiella pneumoniae isolates were significantly more resistant than hvKP to cephalosporins, amoxicillin-clavulanic acid, and fluoroquinolones (p < 0.05). Carbapenem resistance was seen in 10 hvKP convergent isolates with the most prevalent carbapenemase-encoding gene being OXA-48 and OXA-181 in 50% isolates.

Conclusion

There is a need for continued surveillance of hvKP strains in view of the impending threat of a global spread of convergent strains.

Hypervirulence and Multiresistance to Antibiotics in Klebsiella pneumoniae Strains Isolated from Patients with Hospital- and Community-Acquired Infections in a Mexican Medical Center

Klebsiella pneumoniae is a pathogenic bacterium associated with different infectious diseases. This study aimed to establish the different association profiles of virulence genes related to the hypermucoviscous phenotype (HM), capsular serotypes, biofilm formation, and multidrug resistance in K. pneumoniae strains from patients with hospital- and community-acquired infections. K. pneumoniae virulence genes and capsular serotypes were identified by PCR, antibiotic susceptibility by the Kirby-Bauer method, HM by the string test, and biofilm formation by measurement in polystyrene microtiter plates. Of a total of 150 strains from patients with hospital- (n = 25) and community-acquired infections (n = 125), 53.3% (80/150) were HM-positive and 46.7% (70/150) were HM-negative. HM-positive (68/80) and HM-negative (67/70) strains were biofilm-forming. Moreover, 58.7% (47/80) HM-positive and 57.1% (40/70) HM-negative strains were multidrug-resistant. Among HM-positive, HM-negative, and serotypes K1 (25/150), K2 (48/150), and non-K1/K2 strains, (77/150) the frequently detected adhesion genes were fimH, mrkD, ycfM, and kpn; entB, irp2, irp1, and ybtS, for iron acquisition; and rmpA for protectins. The gene association pattern fimH/kpn/mrkD/ycfM/entB/irp1/irp2/ybtS/fyuA (18/150) was frequent among the strains. K. pneumoniae strains from patients with hospital- and community-acquired infections demonstrated a wide diversity of virulence gene profiles related to phenotype (hypermucoviscosity, multidrug resistance, and biofilm formation) and serotypes.

Detection of extensively drug-resistant and hypervirulent Klebsiella pneumoniae ST15, ST147, ST377 and ST442 in Iran

In this study, we focused on the emergence of extensively drug-resistant (XDR), pandrug-resistant (PDR), and hypervirulent Klebsiella pneumoniae (hvKP) in Iran. During 2018 to 2020 a total of 52 K. pneumoniae isolates were collected from different clinical specimens. The hvKP isolates were identified by PCR amplification of virulence and capsular serotype-specific genes. Hypermucoviscous K. pneumoniae (hmKP) were identified by string test. Carbapenem-resistant hvKP (CR-hvKP), multidrug-resistant hvKP (MDR-hvKP), extensively drug-resistant hvKP (XDR-hvKP), and pandrug-resistant hvKP (PDR-hvKP) were determined by disc diffusion method, Carba-NP test and PCR method. XDR-hvKP isolates were typed by multilocus sequence typing (MLST). Among all K. pneumoniae isolates 14 (26.9%) were identified as hvKP and 78.6% (11/14) of them were hmKP however, none of the classic K. pneumoniae (cKP) isolates were hmKP. The predominant capsular serotype of hvKP was K2 (42.85%) followed by K1 (35.71%). The prevalence of MDR-hvKP, XDR-hvKP and PDR-hvKP isolates were 6 (42.9%), 5 (35.7%) and 1 (7.1%), respectively. ESBL production was found in 85.7% of hvKP isolates and most of them carried bla TEM gene (78.6%) and 6 isolates (42.9%) were CR-hvKP. Among hvKP isolates, 1 (7.1%), 2 (14.3%), 3 (21.4%), 8 (28.6%), and 11 (78.6%) carried bla NDM-6, bla OXA-48, bla CTX-M, bla SHV, and bla TEM genes, respectively. According to MLST analysis, 2, 1, 1, and 1 XDR-hvKP isolates belonged to ST15, ST377, ST442, and ST147, respectively. The occurrence of such isolates is deeply concerning due to the combination of hypervirulence and extensively drug-resistance or pandrug-resistance.

Bacteriostatic Potential of Melatonin: Therapeutic Standing and Mechanistic Insights

Diseases caused by pathogenic bacteria in animals (e.g., bacterial pneumonia, meningitis and sepsis) and plants (e.g., bacterial wilt, angular spot and canker) lead to high prevalence and mortality, and decomposition of plant leaves, respectively. Melatonin, an endogenous molecule, is highly pleiotropic, and accumulating evidence supports the notion that melatonin's actions in bacterial infection deserve particular attention. Here, we summarize the antibacterial effects of melatonin in vitro, in animals as well as plants, and discuss the potential mechanisms. Melatonin exerts antibacterial activities not only on classic gram-negative and -positive bacteria, but also on members of other bacterial groups, such as Mycobacterium tuberculosis. Protective actions against bacterial infections can occur at different levels. Direct actions of melatonin may occur only at very high concentrations, which is at the borderline of practical applicability. However, various indirect functions comprise activation of hosts' defense mechanisms or, in sepsis, attenuation of bacterially induced inflammation. In plants, its antibacterial functions involve the mitogen-activated protein kinase (MAPK) pathway; in animals, protection by melatonin against bacterially induced damage is associated with inhibition or activation of various signaling pathways, including key regulators such as NF-κB, STAT-1, Nrf2, NLRP3 inflammasome, MAPK and TLR-2/4. Moreover, melatonin can reduce formation of reactive oxygen and nitrogen species (ROS, RNS), promote detoxification and protect mitochondrial damage. Altogether, we propose that melatonin could be an effective approach against various pathogenic bacterial infections.

Virulence Factors in Hypervirulent Klebsiella pneumoniae

Hypervirulent Klebsiella pneumoniae (hvKP) has spread globally since first described in the Asian Pacific Rim. It is an invasive variant that differs from the classical K. pneumoniae (cKP), with hypermucoviscosity and hypervirulence, causing community-acquired infections, including pyogenic liver abscess, pneumonia, meningitis, and endophthalmitis. It utilizes a battery of virulence factors for survival and pathogenesis, such as capsule, siderophores, lipopolysaccharide, fimbriae, outer membrane proteins, and type 6 secretion system, of which the former two are dominant. This review summarizes these hvKP-associated virulence factors in order to understand its molecular pathogenesis and shed light on new strategies to improve the prevention, diagnosis, and treatment of hvKP-causing infection.

Genetic analysis of ESBL-producing Klebsiella pneumoniae isolated from UTI patients in Indonesia

INTRODUCTION

Extended spectrum beta-lactamase (ESBL)-producing Klebsiellapneumoniae is a serious concern for nosocomial infection and the emergence rate in Indonesia is higher than that in developed countries. The purpose of this study was to investigate the genetic characteristics of ESBL-producing K. pneumoniae isolated from UTI patients in Indonesia.

MATERIALS AND METHODS

We collected K. pneumoniae resistant to ceftazidime or cefotaxime isolated from UTI patients in Dr. Soetomo's Academic Hospital in Surabaya, Indonesia in 2015. Ninety-four strains were identified as ESBL-producing bacteria by confirmation tests. The isolates were investigated by antimicrobial susceptibility testing with 20 drugs and ESBL gene detection, plasmid replicon typing and virulence genes as hypermucoviscous (HMV) strains were tested by the string test.

RESULTS

High rates of resistance to ciprofloxacin (86.2%), tetracycline (80.9%) and nalidixic acid (78.7%) were observed. CTX-M-15 was the most common ESBL gene (89.4%), 33 of which also carried SHV-type ESBL. IncF was the most prevalent plasmid replicon typing (47.6%). Sixteen (17.0%) strains were judged as HMV, all of which had rmpA and more than half of which had fimH, uge, and wab. IncL/M was the most common replicon plasmid in the HMV strains, and the difference in the positive rate was statistically significant (p = 0.0024).

CONCLUSION

This study showed the high prevalence of multiple-drug resistant and predominately CTX-M-15-positive ESBL-producing K. pneumoniae in Indonesia. There was a correlation between IncL/M and the HMV phenotype in this study. As such hypervirulent strains continue to emerge, studying their dissemination with resistance determinants is an urgent priority.

Virulence Factors, Capsular Serotypes and Antimicrobial Resistance of Hypervirulent Klebsiella pneumoniae and Classical Klebsiella pneumoniae in Southeast Iran

BACKGROUND

The present study was conducted to investigate the distribution of virulence factors, capsular serotypes and antibiotic resistance properties of classical Klebsiella pneumoniae (cKP) and hypermucoviscous/hypervirulent Klebsiella pneumoniae (hvKP) isolated from different clinical specimens in Kerman, south-east of Iran.

MATERIALS AND METHODS

A total of 146 K. pneumoniae isolates were obtained from different clinical specimens. HvKP isolates were identified using the string test. Genes of capsular serotypes K1, K2, K5, K20, K54 and K57 and virulence-associated genes, rmpA, kfu, fimH, mrkD, allS, iutA, magA, entB and ybtS were evaluated by PCR. Antimicrobial susceptibility was also determined using the disc diffusion method.

RESULTS

Out of 146 K. pneumoniae isolates, 22 (15.1 %) were hvKP. More than half of the hvKP isolates, 13 (59.1%), belonged to non-K1, K2, K5, K20, K54, K57 serotypes. Out of 22 hvKP isolates, 3 and 3 had K1 and K2 serotypes respectively. Among all isolates, entB 140 (95.9%) and mrkD 138 (94.5%) were the most common virulence genes. RmpA, iutA and kfu were associated with hvKP isolates (P-value <0.05). However, no significant difference was found in fimH, allS, mrkD, entB and ybtS genes between hvKP and cKP strains. HvKP exhibited significantly lower resistance rates to all antimicrobial agents than cKP, except to trimethoprim-sulphamethoxazole and ampicillin (P-value <0.05).

CONCLUSION

The frequency of hvKP was low, but overall, the prevalence of virulence-related genes was higher in hvKP than cKP. HvKP was not related to specific serotypes. Furthermore, hvKP isolates were more susceptible to antimicrobial agents compared to cKP isolates.

Hypervirulent Klebsiella pneumoniae

Hypervirulent K. pneumoniae (hvKp) is an evolving pathotype that is more virulent than classical K. pneumoniae (cKp). hvKp usually infects individuals from the community, who are often healthy. Infections are more common in the Asian Pacific Rim but are occurring globally. hvKp infection frequently presents at multiple sites or subsequently metastatically spreads, often requiring source control. hvKp has an increased ability to cause central nervous system infection and endophthalmitis, which require rapid recognition and site-specific treatment. The genetic factors that confer hvKp's hypervirulent phenotype are present on a large virulence plasmid and perhaps integrative conjugal elements. Increased capsule production and aerobactin production are established hvKp-specific virulence factors. Similar to cKp, hvKp strains are becoming increasingly resistant to antimicrobials via acquisition of mobile elements carrying resistance determinants, and new hvKp strains emerge when extensively drug-resistant cKp strains acquire hvKp-specific virulence determinants, resulting in nosocomial infection. Presently, clinical laboratories are unable to differentiate cKp from hvKp, but recently, several biomarkers and quantitative siderophore production have been shown to accurately predict hvKp strains, which could lead to the development of a diagnostic test for use by clinical laboratories for optimal patient care and for use in epidemiologic surveillance and research studies.

Molecular characterization, serotypes and phenotypic and genotypic evaluation of antibiotic resistance of the Klebsiella pneumoniae strains isolated from different types of hospital-acquired infections

Purpose: Virulent and resistant Klebsiella pneumoniae strains are considered as one of the most significant causes of hospital-acquired infections. The present investigation was done to study the distribution of virulence factors, capsule serotypes and phenotypic and genotypic evaluation of antibiotic resistance of the K. pneumoniae strains isolated from hospital-acquired infections.

Patients Materials and methods: Two hundred and sixty different types of hospital-acquired infections were collected and cultured. Antibiotic resistance pattern of K. pneumoniae isolates and their molecular characterization were studied using disk diffusion and PCR, respectively.

Results: One hundred and fifty out of 260 (44.22%) hospital-acquired infections harbored K. pneumoniae. Urine samples (63.75%) had the highest prevalence of K. pneumoniae, while wound (33.33%) had the lowest. K. pneumoniae strains harbored the highest prevalence of resistance against ampicillin (100%), cefuroxime (100%), amoxicillin/clavulanic acid (95.65%) and ceftazidime (95.52%). FimH-1 (93.04%), traT (92.17%), mrkD (84.34%), and entB (80.86%) were the most commonly detected virulence genes. AcrAB (96.52%) and tolC (85.21%) were the most commonly detected antibiotic resistance genes. Prevalence of ompK35 and ompK36 virulence genes were 75.65% and 79.13%, respectively. Prevalence of K1 and K2-positive serotypes were 27.82% and 6.96%, respectively.

Conclusions: High prevalence of resistance against several types of antibiotics and simultaneous presence of some virulence factors and multi-drug resistance genes pose an important public health issue.

DETECTION OF GENETIC DETERMINANTS OF PATHOGENICITY OF STRAINS OF KLEBSIELLA SPP. ISOLATED FROM THE INTESTINAL BIOTOPE OF CHILDREN WITH FUNCTIONAL GASTROINTESTINAL DISORDERS

Functional gastrointestinal disorders (FGID) are one of the most common problems in children of the first year of life. The aim of the study was to assess the pathogenic potential of Klebsiella spp. strains, isolated from the colon in children of the first year of life with FGID. Material for the study included 61 coprological samples. The biological material was divided into comparison groups, depending on the type of Klebsiella excreted at a concentration of 105–108 CFU/g: 1st – with vegetation in the colon K. pneumoniae (n = 30); 2nd – with vegetation K. oxytoca (n = 31). Bacteriological study composition of the intestinal contents was carried out according to the Industry standard “Protocol of management of patients. Intestinal dysbiosis” (2003). Identification was carried out according to generally accepted schemes using commercial test systems for biochemical identification of bacteria. Statistical data processing was performed using licensed applications “MS Office Excel 2003 for Windows 7”. The data on the quantitative and qualitative changes in the composition microbiota in the comparison groups were obtained. The results of detection genetic determinants of pathogenicity in the samples of Klebsiella of two species show that among the strains of Klebsiella spp., vegetating in the intestines of children as a component of an allochthonous microbiota, a sufficiently high and virulent potential can be concentrated. Detection of pathogenicity genes in bacteria of the genus Klebsiella will expand and deepen the problem of finding the structures of adaptation of strains of bacteria that cause FGID in children of the first year of life.

Hypervirulent Klebsiella pneumoniae as a hospital-acquired pathogen in the intensive care unit in Mansoura, Egypt

Introduction

Hypervirulent Klebsiella pneumoniae (hvKP) are variants of K. pneumoniae that come up worldwide. hvKP is known in community-acquired infections but little is known about its role in hospital-acquired (HA) infections. The aim of this study was to evaluate the frequency of hvKP among HA K. pneumoniae infections in the intensive care unit (ICU) and to compare virulence and antibiotic susceptibility between hvKP and classical K. pneumoniae (cKP).

Methods

String test, biofilm formation, serum bactericidal assay, capsular polysaccharide genes (K1, K2, K5, K20, K54, K57), virulence genes: rmpA, rmpA2, iucA, iroB and antimicrobial susceptibility were assessed in HA K. pneumoniae strains isolated from the ICU in Mansoura, Egypt.

Results

Probable hvKP represented 4 out of 65 (6.2%) K. pneumoniae. K1 and K2 genes were present in 2 and 1 isolate respectively in probable hvKP. rmpA genes were significantly associated with hvKP; at the same time biofilm production and serum resistance were not significantly associated with the hypervirulent group. There was no significant difference between hvKP and cKP strains in terms of resistance pattern.

Conclusion

hvKP in critically ill patients from the ICU may form a new threat especially in the presence of antibiotic resistance. Although the validity of the string test in detecting metastatic Klebsiella is questionable, it is a simple and easy test that can be done in any laboratory indicating the presence of this organism. Serotypes and genomic background may provide helpful and confirmatory tools to diagnose hvKP.