Compared to classical Klebsiella pneumoniae, hypervirulent Klebsiella pneumoniae (hvKP) exhibits stronger pathogenicity and a greater ability to evade host immune responses. Infections caused by hvKP typically manifest as more severe diseases with higher mortality rates, thereby increasing the complexity and challenges of clinical treatment. The emergence of carbapenem-resistant hvKP (CR-hvKP) exacerbates this predicament. Although there is still confusion regarding the clinical definition and detection standards for hvKP, this article systematically explains the clinical infection characteristics, identification methods, and mechanisms behind the emergence of CR-hvKP. This can enhance clinical staff’s vigilance towards hvKP infections and offer comprehensive and detailed considerations for the diagnosis and treatment of such strains.
ObjectiveTo study the distributions of virulence genes of Klebsiella pneumoniae (KP) and the distribution of hypervirulent KP (HvKP), and assess the performance of a single gene to predict HvKP.MethodsPolymerase chain reaction (PCR) method was used to analyze 12 virulence-related genes (entB, irp2, iroN, iucA, mrkD, fimH, c-rmpA, p-rmpA2, p-rmpA, wzy-K1, allS and peg-344) and drug-resistance gene blaKPC among 376 clinical KP strains collected from January 2016 to December 2018. Sequence types (ST) of KP were determined after sequencing and comparison, following the detection of 7 house-keeping genes (gapA, infB, mdh, pgi, phoE, rpoB and tonB) by PCR method. Statistical analyses were made for the distributions of virulence genes of KP and the distribution of HvKP with GraphPad Prism 8 software.ResultsAmong the 376 KP strains, the positive rates of entB, irp2, iroN, iucA, mrkD, fimH, c-rmpA, p-rmpA2, p-rmpA, wzy-K1, allS and peg-344 were 100.0%, 76.9%, 22.1%, 28.2%, 97.6%, 97.1%, 1.6%, 24.5%, 21.0%, 7.4%, 4.8% and 31.6%, respectively. The positive rates of the aforementioned virulence genes in the blaKPC-positive group (n=167) were 100.0%, 94.0%, 7.2%, 16.8%, 97.0%, 96.4%, 0.0%, 15.0%, 6.6%, 0.0%, 0.0% and 21.0%, respectively, and those in the blaKPC-negative group (n=209) were 100.0%, 63.2%, 34.0%, 37.3%, 98.1%, 97.6%, 2.9%, 32.1%, 32.5%, 13.4%, 8.6% and 40.2%, respectively; there was no statistically significant difference in entB, mrkD or fimH between the two groups (P>0.05), the positive rate of irp2 was higher in the blaKPC-positive group than that in the blaKPC-negative group (P<0.05), and the positive rates of the rest virulence-related genes were lower in the blaKPC-positive group than those in the blaKPC-negative group (P<0.05). The rate of HvKP in the blaKPC-negative group was higher than that in the blaKPC-positive group (38.3% vs. 18.0%, P<0.05). As a marker of HvKP, iucA showed high sensitivity and specificity (90.9% and 97.7%), followed by p-rmpA2 (83.6% and 100.0%) and iroN (73.6% and 99.2%). ST11 accounted for 87.4% in the blaKPC-positive group, while ST23, ST20, ST54 and ST29 were the four primary types in the blaKPC-negative group, accounting for 23.4% totally.ConclusionsDifferent virulence genes mean different distributions in KP. blaKPC-negative KP is more virulent than blaKPC-positive KP. iucA and p-rmpA2 could serve as good predicators of HvKP. Armed with extreme virulence and drug-resistance, blaKPC-positive HvKP is of great clinical concern.
Hypervirulent Klebsiella pneumoniae has the characteristics of high virulence and high viscosity, which can cause pneumonia, bacteremia, liver abscess, meningitis and other diseases, and in severe cases, it can be life-threatening. At present, studies on the pathogenic mechanism of hypervirulent Klebsiella pneumoniae showed that siderophore virulence genes play an important role in it. The siderophores closely related to hypervirulent Klebsiella pneumoniae virulence mainly include aerobactin, enterobactin, yersiniabactin and salmochelin. Siderophore-related virulence genes mainly include aer, iucB, iroNB and kfuBC. This article focuses on a brief review of the role of siderophore virulence genes in the pathogenic mechanism of hypervirulent Klebsiella pneumoniae, and aims to guide infection control.
Objective To investigate the risk factors for Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections, and construct a clinical model for predicting the risk of CRKP infections. Methods A retrospective analysis was performed on Klebsiella pneumoniae infection patients hospitalized in the Third Hospital of Hebei Medical University from May 2020 to May 2021. The patients were divided into a CRKP group (117 cases) and a Carbapenem-sensitive Klebsiella pneumoniae (CSKP) group (191 cases). The predictors were screened by full subset regression using R software (version 4.3.1). The truncation values of continuous data were determined by Youden index. Nomogram and score table model for CRKP infections risk prediction was constructed based on binary logistic regression. The receiver operator characteristic (ROC) curve and area under curve (AUC) were used to evaluate the accuracy of models. Calibration curve and decision curve were used to evaluate the performance of models. Results308 patients with Klebsiella pneumoniae infections were included. A total of 8 predictors were selected by using full subset regression and truncation values were determined according to Youden index: intensive care unit (ICU) stay at time of infection>2 days, male, acute physiology and chronic health evaluation Ⅱ (APACHEⅡ) score>15 points, hospitalization stay at time of infection>10 days, any history of Gram-negative bacteria infection in the last 6 months, heart disease, lung infection, antibiotic exposure history in the last 6 months. The AUC of CRKP prediction risk curve model was 0.811 (95%CI 0.761 - 0.860). When the optimal cut-off value of the constructed CRKP prediction risk rating table was 6 points, the AUC was 0.723 (95%CI 0.672 - 0.774). The Bootstrap method was used for internal repeated sampling for 1000 times for verification. The model calibration curve and Hosmer-Lemeshow test (P=0.618) showed that these models have good calibration degree. The decision curve showed that these models have good clinical effectiveness. Conclusion The prediction model of CRKP infections based on the above 8 risk factors can be used as a risk prediction tool for clinical identification of CRKP infections.
ObjectiveTo evaluate the burden of carbapenem-resistant Klebsiella pneumoniae (CRKPN) and carbapenem-resistant Escherichia coli (CRECO), two types of carbapenem-resistant Enterobacteriaceae (CRE), in pediatric patients in Jiangxi Province.MethodsA retrospective investigation was carried out for the distribution of CRKPN/CRECO in pediatric (neonatal group and non-neonatal group) and adult patients in 30 hospitals in Jiangxi Province from January 2016 to December 2018, and the changing trends and detection situations of different patients and types of hospitals were compared and analyzed.ResultsFrom 2016 to 2018, the annual resistance rates of Klebsiella pneumoniae and Escherichia coli to carbapenem in pediatric patients were 5.89%, 4.03%, and 4.24%, respectively, showed a downward trend (χ2trend=5.568, P=0.018). The resistance rate of Klebsiellae pneumoniae and Escherichia coli to carbapenem in neonatal group was higher than that in non-neonatal group (8.44% vs. 3.40%; χ2=63.155, P<0.001) and adult group (8.44% vs. 3.45%; χ2=97.633, P<0.001). In pediatric patients, the 3-year carbapenem resistance rate of Klebsiella pneumoniae was higher than that of Escherichia coli (9.10% vs. 2.48%; χ2=128.177, P<0.001). In non-neonatal pediatric patients, the 3-year resistance rate of Klebsiella pneumoniae and Escherichia coli to carbapenem in maternity and children hospitals was higher than that in general hospitals (4.35% vs. 1.36%; χ2=25.930, P<0.001). CRKPN/CRECO detected in pediatrics were mainly isolated from sputum (31.64%), blood (24.36%), urine (13.82%), and pus (8.36%).ConclusionAlthough the overall resistance rate of Klebsiella pneumoniae and Escherichia coli to carbapenem in pediatric patients showed a downward trend, that in neonatal patients was still high, and the monitoring and prevention and control measures of CRE should be strengthened in neonatal patients.
Objective To analyze the current drug resistance and risk factors of hospital acquired pneumonia( HAP) due to extended spectrumβ-lactamase ( ESBLs) producing Escherichia coli and Klebsiella pneumoniae, and to estimate the prevalence trend of ESBLs producing strains. Methods FromApril 2007 to January 2008, 140 patients of Xinhua Hospital with HAP due to E. coli and K. pnermoniae were enrolled.Among them, 88 patients were with ESBLs producing strains and 52 patients were with non-ESBLs producing strains. Risk factors were analyzed by comparing between these patients. The rate of drug resistance was determined by antibiotic sensitive test. Fifty-three ESBLs producing strains were genotyped by random amplified polymorphic DNA ( RAPD) . Results The rate of drug resistance of ESBLs producing strains washigher than that of non-ESBLs producing strains. ICU stay, use of third- and forth-generation cehpalosporin were found to be the independent risk factors by multivariate analysis with logistic regression. By RAPD, 37 ESBLs producing E. coli strains were divided into 27 types and 16 ESBLs producing K. pneumoniae strains were divided into 13 types. Conclusions ICU stay, use of third-generation and forth-generation cehpalosporin remain as major risk factors in the HAP due to ESBLs producing E. coli and K. pneumoniae.RAPD is an economic, quick and credible method for epidemic analysis
Objective To investigate the iron regulated locus in Klebsiella pneumoniae isolates from blood culture of liver abscess patients in Sichuan Provincial People’s Hospital. Methods From January to December of 2015, a total of 10 isolates of Klebsiella pneumoniae were collected from blood culture of liver abscess patients from Sichuan Provincial People’s Hospital. The genomic DNA was extracted to identify the genes of iroB, iroC, and iroD by PCR, and data was further analyzed by Graphpad Prism 5 software. Results Among the 10 Klebsiella pneumoniae clinical strains, 9 strains were iroB positive strains, 9 strains were iroC positive strains, and 10 strains were iroD positive strains, 9 strains were iroB/C/D triple positive. Conclusion The current study suggests that the frequency of triple positive of iroB/C/D in Klebsiella pneumoniae is high in isolates from liver abscess patients, the triple positive of iroB/C/D may contribute to liver abscess.
ObjectiveTo evaluate the relationship between the genes involved in regulating iron uptake and maintaining iron homeostasis in Klebsiella pneumoniae from different sources and pathogenicity.MethodsThe genomic DNA sequences of two strains of Klebsiella pneumoniae from different sources were sequenced, stitched together, annotated and analyzed by second generation sequencing technique. The transversal comparison between different types of Klebsiella pneumoniae in NCBI database of iron carrier gene cluster iroB/C/D.ResultsIn these two Klebsiella pneumoniae clinical strains, the strain isolated from liver abscess patient carried 11 different iron acquisition and transportation system specific genes, which were not found in the non-liver abscess patient strain. Combined with the analysis of this sequence, in the NCBI database, six different strains of Klebsiella pneumoniae showed iroB/C/D triple positive.ConclusionIron acquisition and transportation system in Klebsiella pneumoniae may be an important pathogenic factor, which is closely related to hepatic abscess.
Objective To compare the screening ability of modified Hodge test (MHT), modified carbapenem inactivation method (mCIM) and EDTA-carbapenem inactivation method (eCIM) for drug resistance phenotype of carbapenemase-producing Klebsiella pneumoniae. MethodsCarbapenem resistant Klebsiella pneumoniae (CRKP) strains clinically isolated from 5 hospitals in Chengdu between January 2019 and December 2021 were collected, and the carbapenem sensitive Klebsiella pneumoniae (CSKP) strains isolated in the same period were randomly collected. Polymerase chain reaction (PCR) -amplified carbapenem resistance gene as the gold standard, the consistencies between the results of the three phenotypic tests and the results of genetic testing were compared. Results A total of 160 CRKP strains and 120 CSKP strains were isolated. Among the 160 CRKP strains, carbapenem resistance genes were detected in 156 strains, including 105 strains of blaKPC-2, 41 strains of blaNDM-1, 8 strains of blaKPC-19, 1 strain of blaIMP-1, and 1 strain carrying both blaKPC-2 and blaNDM-1. None of the 120 CSKP drug resistance genes were detected. The sensitivity and specificity of carbapenem screening for MHT and mCIM were 73.08% (114/156), 96.67% (116/120), 97.44% (152/156) and 98.33% (118/120), respectively. The sensitivity and specificity of eCIM for screening metalloenzymes were 95.35% (41/43) and 100% (120/120), respectively. Conclusions The sensitivity of MHT to detect carbapenemase is lower than that of the other two methods, and it is easy to produce false negatives when it is used to detect metalloenzymes. The mCIM has high sensitivity and is consistent with the PCR genetic test results. The combined detection of mCIM and eCIM can screen carbapenemases more effectively and distinguish the types of carbapenemases.
ObjectiveTo retrospectively analyze antibiotic resistance and clinical characteristics of Klebsiella pneumoniae strains for guiding the rational use of antibiotics in the area of the Bai nationality.MethodsThe antibiotic resistance and clinical characteristics of Klebsiella pneumoniae strains were retrospective analyzed, which were isolated from specimens of inpatients in First People’s Hospital of Dali between May 2016 and May 2017.ResultsAmong the 1 342 samples of various kinds of samples, 262 strains of Klebsiella pneumoniae were isolated, with the detection rate of 19.52% (262/1342). Clinical isolated strains were mainly from the new pediatric, intensive care unit, respiratory medicine, pediatrics, and mostly from sputum specimens (78.24%, 205/262). By screening of 22 kinds of antimicrobial agents, all strains had ampicillin resistance (100.00%), while none of these strains had ertapenem resistance. Extended-spectrum β-lactamases (ESBLs) positive strains’ resistance rate was higher than ESBLs negative strains (χ2=261.992, P<0.01). There were 76 drug resistant profiles, most of which were multidrug-resistant bacteria except 116 (44.27%) strains were resistant to ampicillin antibiotics only. And the number of strains in other resistant types ranged from 1 to 16. Only one of 262 strains had amikacin resistance, two of them were resistant to imipenem and meroenan.ConclusionsThere are many multidrug-resistant bacteria in Klebsiella pneumoniae in the population of Bai nationality, and there are no extensively drug resistant bacteria and pandrug-resistant bacteria strains. The strains of carbapene-resistant antibiotics should be worthy of clinical attention.