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Introduction: The clinical and molecular characteristics of hypervirulent Klebsiella pneumoniae (hvKp) in various provinces of China have been reported, however, there have been few reports in Hebei Province, North China. Methodology: The hvKp was identified by PCR amplification of hypervirulence-related genes, the hypermucoviscous phenotype was determined by the \"string test\", the drug susceptibility analysis was performed using the VITEK® 2 Compact Bacterial Identification and Monitoring System. Logistic regression was used to identify risk factors for hvKp infection. The molecular epidemiological characteristics of the strains were analyzed by pulsed-field gel electrophoresis (PFGE), and the capsular serotype of hvKp strain was detected by PCR. Results: Overall, 52.21% (59/113) of K. pneumoniae isolates were hvKp, and the ratios of patients with older ages or a higher PMN cell count among hvKp infection were higher than those among classical Klebsiella pneumoniae (cKp) infection. hvKp are more susceptible to antibacterial drugs than cKp, and one ESBLs-producing hvKp strain was detected. The main capsular serotype of hvKp were K2, K57 and K1. PFGE indicated that the 59 strains of hvKp could be classified into 51 PFGE band types, forming 6 PFGE clusters. Conclusions: In this study, the detection rate of hvKp was 52.21% (59/113) identified by virulence genes. People with older ages or a higher PMN cell count are more likely to gain hvKp infection. ESBLs-producing hvKp is emerging, indicating the importance of epidemiologic surveillance and clinical awareness of this pathogen in this region.

Hypervirulent Klebsiella pneumoniae (hvKp) raised concern worldwide. We studied 22 hvKp clinical invasive isolates referred to the Belgian national reference laboratory between 2014 and 2020. Sixty-four percent of the isolates expressed K2 capsular serotype and belonged to 7 different MLST lineages, while 32% expressed K1 (all belonging to ST23) and were associated with liver abscesses. Primary extra-hepatic infections were reported in 36% and sepsis for 95% of the patients with 30% of deaths. Improved clinical and microbiological diagnostics are required as hvKp may represent an underestimated cause of community-acquired invasive infections in Belgium.

The distributions and frequencies of individual pneumococcal capsular serotypes among nonpneumococcal strains in the upper respiratory tract are unknown and potentially affect pneumococcal serotype distributions among the population and immunity to circulating pneumococcal strains. Repeated demonstration that these nonpneumococcal strains expressing so-called pneumococcal serotypes are readily recovered from current carriage specimens is likely to be relevant to pneumococcal epidemiology, niche biology, and even to potential strategies of employing commensal live vaccines. The polysaccharide capsule is a key virulence factor of Streptococcus pneumoniae . There are numerous epidemiologically important pneumococcal capsular serotypes, and recent findings have demonstrated that several of them are commonly found among nonpathogenic commensal species. Here, we describe 9 nonpneumococcal strains carrying close homologs of pneumococcal capsular biosynthetic ( cps ) loci that were discovered during recent pneumococcal carriage studies of adults in the United States and Kenya. Two distinct Streptococcus infantis strains cross-reactive with pneumococcal serotype 4 and carrying cps4 -like capsular biosynthetic ( cps ) loci were recovered. Opsonophagocytic killing assays employing rabbit antisera raised against S. infantis US67cps4 revealed serotype 4-specific killing of both pneumococcal and nonpneumococcal strains. An S. infantis strain and two Streptococcus oralis strains, all carrying cps9A- like loci, were cross-reactive with pneumococcal serogroup 9 strains in immunodiffusion assays. Antiserum raised against S. infantis US64cps9A specifically promoted killing of serotype 9A and 9V pneumococcal strains as well as S. oralis serotype 9A strains. Serotype-specific PCR of oropharyngeal specimens from a recent adult carriage study in the United States indicated that such nonpneumococcal strains were much more common in this population than serotype 4 and serogroup 9 pneumococci. We also describe S. oralis and S. infantis strains expressing serotypes identical or highly related to serotypes 2, 13, and 23A. This study has expanded the known overlap of pneumococcal capsular serotypes with related commensal species. The frequent occurrence of nonpneumococcal strains in the upper respiratory tract that share vaccine and nonvaccine capsular serotypes with pneumococci could affect population immunity to circulating pneumococcal strains. IMPORTANCE The distributions and frequencies of individual pneumococcal capsular serotypes among nonpneumococcal strains in the upper respiratory tract are unknown and potentially affect pneumococcal serotype distributions among the population and immunity to circulating pneumococcal strains. Repeated demonstration that these nonpneumococcal strains expressing so-called pneumococcal serotypes are readily recovered from current carriage specimens is likely to be relevant to pneumococcal epidemiology, niche biology, and even to potential strategies of employing commensal live vaccines. Here, we describe multiple distinct nonpneumococcal counterparts for each of the pneumococcal conjugate vaccine (PCV) serotypes 4 and 9V. Additional data from contemporary commensal isolates expressing serotypes 2, 13, and 23A further demonstrate the ubiquity of such strains. Increased focus upon this serological overlap between S. pneumoniae and its close relatives may eventually prove that most, or possibly all, pneumococcal serotypes have counterparts expressed by the common upper respiratory tract commensal species Streptococcus mitis , Streptococcus oralis , and Streptococcus infantis .

Periodontitis is a chronic inflammation that develops due to a destructive tissue response to prolonged inflammation and a disturbed homeostasis (dysbiosis) in the interplay between the microorganisms of the dental biofilm and the host. The infectious nature of the microbes associated with periodontitis is unclear, as is the role of specific bacterial species and virulence factors that interfere with the host defense and tissue repair. This review highlights the impact of classical virulence factors, such as exotoxins, endotoxins, fimbriae and capsule, but also aims to emphasize the often-neglected cascade of metabolic products (e.g., those generated by anaerobic and proteolytic metabolism) that are produced by the bacterial phenotypes that survive and thrive in deep, inflamed periodontal pockets. This metabolic activity of the microbes aggravates the inflammatory response from a low-grade physiologic (homeostatic) inflammation (i.e., gingivitis) into more destructive or tissue remodeling processes in periodontitis. That bacteria associated with periodontitis are linked with a number of systemic diseases of importance in clinical medicine is highlighted and exemplified with rheumatoid arthritis, The unclear significance of a number of potential “virulence factors” that contribute to the pathogenicity of specific bacterial species in the complex biofilm–host interaction clinically is discussed in this review.

Group B Streptococcus (GBS), a causative agent of newborn infection, colonizes the digestive system and genitourinary tracts of pregnant women. The aim of this study was to assess the incidence of GBS capsular serotypes, virulence genes, and antibiotic resistance in pregnant women at a prominent maternity hospital in Shahrekord, Chaharmahal and Bakhtiari. From January to July 2022, a total of 370 vaginal swabs were collected from women who were from 28 to 38 weeks pregnant. These swabs were used to identify Streptococcus agalactiae using PCR and culture technique. The capsular serotype of Streptococcus agalactiae isolates, antibiotic resistance and virulence genes distribution were determined through disk diffusion and multiplex PCR methods. mong 370 vaginal samples, 36 (9.72%) isolates were detected by culture and molecular methods, that type III (37.83%) and type V (32.43%) were the most frequent capsular serotypes, and all isolates harbored atr , and dltS genes. Moreover, the most frequent antibiotic resistance genes (62.16%) in the isolates is was related to tetO and ermA. All isolates were resistant to penicillin (100%), and the highest antibiotic susceptibility was found against linezolid (81%). Our study revealed a high rate of antibiotic resistance in Streptococcus agalactiae isolates, that molecular method was reliable approach for identification of infection and detection of harbored resistance genes. However, more studies are required to identification of effective antibiotics against infections and prevention of resistance in pregnant women.

, one of the clinical superbugs, causes diverse infections because of its variable capsular antigens. This study focused on and aimed to assess any correlation between capsular serotype, capsule-associated virulence genes, and evaluate its resistance to conventional antibiotics in order to gain insight into any regional differences. A total of 61 collected from various clinical specimens were confirmed genotypically. Clinical and demographic data for all patients were reviewed. All isolates were subjected to antimicrobial susceptibility tests. Capsular serotyping and capsule-associated virulence genes were studied using the molecular method. All typeable isolates were typed into K5, K20, and K54 serotypes, and among them, K54 was observed to be predominant. The most common capsule-associated virulence genes comprised (93.4%), (91.8%), and (88.5%), while (29.5%) and (21.3%) were noted at much lower prevalence rates. The gene was significantly associated with K54 positive isolates ( = 0.001), while was associated with K20 positive isolates ( = 0.01). Serotype K54 had a high frequency in isolates collected from patients with pulmonary diseases, while serotype K20 was associated with burn patients. Carbapenems and levofloxacin were the best therapeutic options for the treatment of infections with serotypes K20 and K54.

This study aimed to explore the epidemic, clinical characteristics, and molecular and virulence attributes of Klebsiella pneumoniae serotype K54 (K54-Kp). A retrospective study was conducted on 328 strains of Klebsiella pneumoniae screened in a Chinese hospital from January 2016 to December 2019. The virulence genes and antibiotic resistance genes (ARGs) were detected by PCR, and a drug sensitivity test was adopted to detect drug resistance. Multilocus sequence typing (MLST) and PFGE were performed to determine the clonal correlation between isolates. Biofilm formation assay, serum complement-mediated killing, and Galleria mellonella infection were used to characterize the virulence potential. Our results showed that thirty strains of K54-Kp were screened from 328 strains of bacteria, with an annual detection rate of 2.29%. K54-Kp had a high resistance rate to antibiotics commonly used in the clinic, and patients with hepatobiliary diseases were prone to K54-Kp infection. MLST typing showed 10 sequence typing, mainly ST29 (11/30), which concentrated in the B2 cluster. K54-Kp primarily carried virulence genes of aerobactin, silS, allS, wcaG, wabG, and mrkD, among which the terW gene was closely related to ST29 (p<0.05). The strains infected by the bloodstream had strong biofilm formation ability (p<0.05). Most strains were sensitive to serum. Still, the virulence of pLVPK-like virulence plasmid in ST29-K54 Klebsiella pneumoniae was lower than that of ST11 type and NTUH-K2044 in the Galleria mellonella model. Therefore, these findings supply a foundation to roundly comprehend K54-Kp, and clinicians should strengthen supervision and attention.

The purpose of this study was to analyse the clinical, microbiological and molecular epidemiological characteristics of patients with pyogenic liver abscess (PLA) caused by (KPN) in Inner Mongolia, China. The KPN isolates from 78 KPN-PLA cases admitted to a tertiary teaching hospital in Baotou, Inner Mongolia, from 2016 to 2019 were studied systematically and described comprehensively. The virulence factors, drug resistance and sequence types of KPN in different samples were identified by a wire-drawing test, polymerase chain reaction, a drug susceptibility test and multi-site sequence typing. There were more male than female KPN-PLA patients ( <0.05). The mortality rate was 2.5%, and KPN-PLA was significantly associated with diabetes mellitus ( <0.05). Most of the KPN isolates in the puncture fluid of patients with KPN-PLA were hypervirulent KPN (HvKP). The positive rate of the KPN-PLA specimens was higher than that of the blood and urine specimens. The KPN isolates of the urine specimens had higher drug resistance than the other two ( <0.05). The hypermucoviscous KPN, ( ) (+), K1 and K2 serotypes accounted for 80.8%, 89.7%, 56.4% and 26.9%, respectively. In addition to (3.8%), the detection rates of virulence factors and were higher (69.2%-100.0%). The positive rate of KPN isolates of the KPN-PLA puncture fluid was higher than that of the blood and urine samples ( <0.05). In addition, ST23 was found to be the dominant ST (32.1%) of KPN-PLA in the Baotou region. In the KPN-PLA specimens, the KPN isolates were more virulent than those in the blood and urine specimens, and a carbapenem-resistant HvKP strain emerged. This research will help improve the understanding of HvKP and provide useful suggestions for KPN-PLA treatments.

Globally, Klebsiella pneumoniae (K. pneumoniae) has been identified as a serious source of infections. The objectives of our study were to investigate the prevalence of multidrug-resistant (MDR) K. pneumoniae in Tanta University Hospitals, Gharbia Governorate, Egypt; characterize their carbapenem resistance profiles; and identify their different capsular serotypes. We identified and isolated 160 (32%) K. pneumoniae from 500 different clinical samples, performed antimicrobial susceptibility testing, and then used multiplex PCR to detect carbapenemase genes and capsular serotypes K1, K2, K3, K5, K20, K54, and K57. We detected phenotypic carbapenem resistance in 31.3% (50/160) of the isolates; however, molecular assays revealed that 38.75% (62/160) of isolates were carrying carbapenemase-encoding genes. Generally, blaOXA-48 was the prevalent gene (15.5%), followed by blaVIM (15%), blaIMP (7.5%), blaKPC (4%), and blaNDM (3.8%). BlaVIM and blaOXA-48 correlated with phenotypic resistance in 91.67% and 88% of the isolates that harbored them, respectively. Capsular typing showed that the most prevalent pathotype was K1 (30.6%), followed by K57 (24.2%), K54 (19.35%), K20 (9.67%), and K2 (6.45%). A critical risk to community health is posed by the high incidence of multidrug-resistant (MDR) virulent K. pneumoniae isolates from our hospital, and our study examines this pathogen’s public health and epidemiological risks.

(KP) is a common nosocomial pathogen. Capsules are an important component of KP's virulence, among which the K1, K2, K5, K20, K54, and K57 serotypes are predominant and exhibit varying degrees of virulence. The capsule and virulence genes of 150 carbapenem-resistant (CRKP) and 213 carbapenem-sensitive (CSKP) isolates were examined by polymerase chain reaction (PCR). The isolates were tested for hypermucoviscosity by string tests. Phylogenetic relationships between KP isolates were analyzed using multilocus sequence typing (MLST) and a infection model confirmed the differences in virulence. A total of 111 of 363 isolates of KP were detected, the highest detected serotypes were K1, K5, and K2, and CSKP was detected more frequently than CRKP. There was a greater prevalence of K1 and K2 serotypes in CSKP, while in CRKP, K5 serotypes were more prevalent. K1 isolates had the highest detection rates for hypermucoviscosity (hmKP) and hypervirulent (hvKP), and carried the most virulence genes. K54 isolates had the lowest detection rate of hmKP while K5 isolates had the lowest detection rate of hvKP and carried the fewest virulence genes. MLST results for serotypes K1, K20, and K57 showed significant homogeneity, while those for serotypes K2, K5, and K54 showed diversity. The infection model showed that the K1 serotype was the most virulent and the K54 serotype was the weakest. CSKP isolates were detected more frequently than CRKP isolates for capsular serotype detection. K1 isolates had the most virulence gene and strongest virulence, K5 isolates carried the fewest virulence genes, and K54 isolates had the weakest virulence. Furthermore, significant homogeneity was observed among K1, K20, and K57 isolates.