Multiplex PCR for detection of seven virulence factors and K1/K2 capsular serotypes of Klebsiella pneumoniae.
Ontology highlight
ABSTRACT:
SUBMITTER: Compain F
PROVIDER: S-EPMC4313302 | biostudies-literature | 2014 Dec
REPOSITORIES: biostudies-literature
Publications
Multiplex PCR for detection of seven virulence factors and K1/K2 capsular serotypes of Klebsiella pneumoniae.
Compain Fabrice F Babosan Ana A Brisse Sylvain S Genel Nathalie N Audo Jennifer J Ailloud Florent F Kassis-Chikhani Najiby N Arlet Guillaume G Decré Dominique D
Journal of clinical microbiology 20141001 12
A single multiplex PCR assay targeting seven virulence factors and the wzi gene specific for the K1 and K2 capsular serotypes of Klebsiella pneumoniae was developed and tested on 65 clinical isolates, which included 45 isolates responsible for community-acquired severe human infections. The assay is useful for the surveillance of emerging highly virulent strains. ...[more]
Similar Datasets
Project description:Hypervirulent Klebsiella pneumoniae (hvKp) is a variant that has been increasingly linked to severe, life-threatening infections including pyogenic liver abscess and bloodstream infections. HvKps belonging to the capsular serotypes K1 and K2 have been reported worldwide, however, very scarce studies are available on their genomics and virulence. In the current study, we report four hypermucoviscous extended-spectrum β-lactamase-producing hvKp clinical strains of capsular serotype K1 and K2 isolated from pus and urine of critically ill patients in tertiary care hospitals in Oman. These strains belong to diverse sequence types (STs), namely ST-23(K1), ST-231(K2), ST-881(K2), and ST-14(K2). To study their virulence, a Galleria mellonella model and resistance to human serum killing were used. The G. mellonella model revealed that the K1/ST-23 isolate was the most virulent, as 50% of the larvae died in the first day, followed by isolate K2/ST-231 and K2/ST-14, for which 75% and 50% of the larvae died in the second day, respectively. Resistance to human serum killing showed there was complete inhibition of bacterial growth of all four isolates by the end of the first hour and up to the third hour. Whole genome sequencing (WGS) revealed that hvKp strains display a unique genetic arrangement of k-loci. Whole-genome single-nucleotide polymorphism-based phylogenetic analysis revealed that these hvKp isolates were phylogenetically distinct, belonging to diverse clades, and belonged to different STs in comparison to global isolates. For ST-23(K1), ST-231(K2), ST-881(K2), and ST-14(K2), there was a gradual decrease in the number of colonies up to the second to third hour, which indicates neutralization of bacterial cells by the serum components. However, this was followed by a sudden increase of bacterial growth, indicating possible resistance of bacteria against human serum bactericidal activity. This is the first report from Oman detailing the WGS of hvKp clinical isolates and assessing their resistance and virulence genomics, which reinforce our understanding of their epidemiology and dissemination in clinical settings.
| S-EPMC10855873 | biostudies-literature
Project description:Accurate serotyping is essential to monitor the changes in the seroepidemiology of Streptococcus pneumoniae. We devised a simple and schematic sequence-based system of seven multiplex PCRs, in a sequence order based upon Active Bacterial Core surveillance (ABCs) serotype distribution during 2002 to 2003, to reliably deduce specific pneumococcal serotypes. A total of 421 isolates from ABCs were randomly chosen to evaluate this system. Two hundred twenty-nine of the isolates (54.3%) were specifically assigned 1 of 17 serotypes by the multiplex PCR system, with the results in complete concordance with conventional serotyping. One hundred seventy-two additional isolates (40.9%) were assigned to 11 specific sets of 2 to 4 serotypes that with one exception (serotypes 6A and 6B) consisted of the single frequently occurring targeted serotype and 1 to 3 additional rare serotypes primarily within the same serogroup as the targeted serotype. Only 20 isolates (4.8%) could not be assigned specific serotypes or serotype sets, since they were either of rare serotypes not included in the assay design or were nonserotypeable. Overall, we found this system to be highly reliable, with the potential to greatly reduce our reliance upon conventional serotyping. Especially important is the capability of this system to give serotype-determining potential to any facility that lacks the expensive typing sera and expertise needed for conventional serotyping yet has the modest equipment necessary for DNA amplification and electrophoresis.
| S-EPMC1351965 | biostudies-literature
Project description:The capsular polysaccharides in different serotypes of Klebsiella pneumoniae (KP) coded by the (CPS) gene cluster are characterized by a conserved and a hyper-variable region. We performed a virulence study by switching genes in the highly conserved region of the CPS cluster between strains. Six genes in the CPS conserved region in serotype K20, including galF, acidPPc, wzi, wza, wzb and wzc, were knocked out and replaced by the homologous genes from serotype K1. Compared to the parental K20 strain, the mutants showed a decline in lethality (LD50) in mice from 10-fold to > 105-fold and were categorized in terms of the effect on virulence as low (L) for galF and acidPPC, moderate (M) for wzi, and high (H) for wza, wzb and wzc. Although substituting the acidPPC gene from K1 for acidPPC in the K20 strain fully restored virulence, substitution with the wzi, wza, wzb or wzc homologs from K1 did not. The restoration with wzi from K1 led to a partial restoration of virulence, with the LD50 in mice changing from 104 to 103 CFU. For the wza, wzb and wzc genes, Complementation of K20 wza, wzb and wzc from K1 resulted in varied degrees of lethality in mice. Variable improvement in serum killing and phagocytosis was observed when the knockout mutants were compared with the gene-switched strains. In conclusion, homologous genes for capsule synthesis failed to exhibit the same functionality when switched between serotypes and virulence was decreased in different degree in according to the genes' homology.
| S-EPMC5538342 | biostudies-literature
Project description:BackgroundTwo different types of hypervirulent K. pneumoniae (HvKp), the MLST-11 and serotype K1/K2 strains, have been frequently described in recent studies. Although these two types of strains were described to be HvKp, their virulence was not compared. In this study, in vitro and in vivo approaches were used to assess differences in virulence.Materials and methodsA total of twenty-nine isolates, including 6 strains of each of serotype K1 and K2 isolates and 17 strains of ST11 isolates, were selected for this study. Phenotypic tests of virulence were performed by the string test and analysis of the virulent associated genes was detected by PCR. In vitro models of serum resistance and phagocytosis were used as the parameters to assess the virulence. In-frame deletion of virulence-associated genes was performed to study their contributions to virulence. The median lethal dose, i.e., the LD50, in mice was determined following IP injection.ResultsAlthough serotype K1 and K2 strains and ST11 isolates had similar virulence gene profiles, the ST11 isolates showed less serum and phagocytic resistance than the serotype K1/K2 isolates. The mouse lethality test revealed that all ST11 isolates were unable to cause lethality, even at > 107 CFU, while serotypes K1 and K2 showed an LD50 at ≤ 103 CFU. Aerobactin or capsule knockout mutants exhibited a lower LD50 than the parental strain, while capsule mutants showed a more significant decrease in LD50.ConclusionSince there was a significant difference in virulence levels between the two types of HvKp when assessed in in vitro and in vivo models, it may be better to use the designation "HvKp" for some strains based on animal studies to avoid confusion. Virulence and non-virulence could be analysed in a relative manner, especially in comparison studies.
| S-EPMC8218402 | biostudies-literature
Project description:Here we describe a Streptococcus pneumoniae one-step multiplex PCR assay which identifies by amplicon size the seven capsular polysaccharide serotypes targeted by the 7-valent conjugate vaccine. The multiplex PCR assay was used to blindly assay clinical isolates recovered during 1999 in the Republic of Ireland from cases of invasive disease whose serotypes were previously determined by classical methods.
| S-EPMC1169178 | biostudies-literature
Project description:BackgroundKlebsiella pneumoniae causes both nosocomial and community-associated infections. Hypervirulent K. pneumoniae (hvKP), new variant of K. pneumoniae, can cause invasive infections in young healthy individuals as well as in the immunocompromised population. Hypervirulent strains frequently belong to capsular serotypes K1 or K2. Emergence of antimicrobial resistance in hvKP is a cause for concern.Aim and objectiveThe present study was done to detect the K1 and K2 serotypes among clinical isolates of K. pneumoniae, spectrum of infections caused by them and presence of common beta-lactamases encoding genes in them.Materials and methodsA total of 370 isolates of K. pneumoniae, isolated from various clinical samples over a period of 1 year was included in this study. Antibiotic susceptibility testing to various classes of antimicrobials was done as per Clinical and Laboratory Standard Institute guidelines. The presence of K2A (specific to serotype K2), magA (specific to serotype K1), and rmpA genes was detected by multiplex polymerase chain reaction (PCR). Extended-spectrum beta-lactamases (TEM, SHV, and CTX-M), plasmid-mediated AmpCs (MOX, CIT, DHA, ACC, EBC, and FOX), and carbapenemase genes (IMP, VIM, NDM, KPC, and OXA-48) were also determined by PCR.ResultsAmong the 370 isolates, 8 harbored K2A gene and one harbored magA. rmpA gene was detected in three isolates along with K1 or K2 serotypes. Seven K2A-positive isolates were resistant to one or more classes of antimicrobials. The studied ESBL genes were present in four isolates. Two isolates harbored carbapenemase genes (NDM-1, OXA-48) along with ESBLs.ConclusionK2 serotype is more prevalent among hvKP isolates. They can harbor ESBLs and Carbapenemase genes. K1 serotype is rather uncommon in K. pneumoniae. Acquisition of multidrug-resistant genes by these strains adds to their virulence and limits the treatment options.
| S-EPMC6052812 | biostudies-literature
Project description:We developed a multiplex PCR assay capable of identifying two capsular polysaccharide synthesis sequence types (sequence type 258 [ST258] cps-1 and cps-2) in epidemic Klebsiella pneumoniae ST258 strains. The assay performed with excellent sensitivity (100%) and specificity (100%) for identifying cps types in 60 ST258 K. pneumoniae sequenced isolates. The screening of 419 ST258 clonal isolates revealed a significant association between cps type and K. pneumoniae carbapenemase (KPC) variant: cps-1 is largely associated with KPC-2, while cps-2 is primarily associated with KPC-3.
| S-EPMC4068549 | biostudies-literature
Project description:Here, we report the whole-genome sequences of Klebsiella pneumoniae ED2 and ED23, isolated, respectively, from bacteremic patients with liver abscesses (ED2) and patients with primary liver abscess and metastatic meningitis (ED23). Both strains were of multilocus sequence type 23 with capsule serotype K1.
| S-EPMC5073253 | biostudies-literature
Project description:Hypervirulent K. pneumoniae variants (hvKP) have been increasingly reported worldwide, causing metastasis of severe infections such as liver abscesses and bacteremia. The capsular serotype K2 hvKP strains show diverse multi-locus sequence types (MLSTs), but with limited genetics and virulence information. In this study, we report a hypermucoviscous K. pneumoniae strain, RJF293, isolated from a human bloodstream sample in a Chinese hospital. It caused a metastatic infection and fatal septic shock in a critical patient. The microbiological features and genetic background were investigated with multiple approaches. The Strain RJF293 was determined to be multilocis sequence type (ST) 374 and serotype K2, displayed a median lethal dose (LD50) of 1.5 × 102 CFU in BALB/c mice and was as virulent as the ST23 K1 serotype hvKP strain NTUH-K2044 in a mouse lethality assay. Whole genome sequencing revealed that the RJF293 genome codes for 32 putative virulence factors and exhibits a unique presence/absence pattern in comparison to the other 105 completely sequenced K. pneumoniae genomes. Whole genome SNP-based phylogenetic analysis revealed that strain RJF293 formed a single clade, distant from those containing either ST66 or ST86 hvKP. Compared to the other sequenced hvKP chromosomes, RJF293 contains several strain-variable regions, including one prophage, one ICEKp1 family integrative and conjugative element and six large genomic islands. The sequencing of the first complete genome of an ST374 K2 hvKP clinical strain should reinforce our understanding of the epidemiology and virulence mechanisms of this bloodstream infection-causing hvKP with clinical significance.
| S-EPMC5955473 | biostudies-literature
Project description:Klebsiella pneumoniae is an opportunistic Gram-negative bacterium that has become a leading causative agent of nosocomial infections, mainly infecting patients with immunosuppressive diseases. Capsular (K) serotypes K1, K2, K47, and K64 are commonly associated with higher virulence (hypervirulent Klebsiella pneumoniae), and more threateningly, isolates belonging to the last two K serotypes are also frequently associated with resistance to carbapenem (hypervirulent carbapenem-resistant Klebsiella pneumoniae). The prevalence of these isolates has posed significant threats to human health, and there are no appropriate therapies available against them. Therefore, in this study, a method combining immunoinformatics and pangenome analysis was applied for contriving a multiepitope subunit vaccine against these four threatening serotypes. To obtain cross-protection, 12 predicted conserved antigens were screened from the core genome of 274 complete Klebsiella pneumoniae genomes (KL1, KL2, KL47, and KL64), from which the epitopes of T and B cells were extracted for vaccine construction. In addition, the immunological properties, the interaction with Toll-like receptors, and the stability in a simulative humoral environment were evaluated by immunoinformatics methods, molecular docking, and molecular dynamics simulation. All of these evaluations indicated the potency of this constructed vaccine to be an effective therapeutic agent. Lastly, the cDNA of the designed vaccine was optimized and ligated to pET-28a(+) for expression vector construction. Overall, our research provides a newly cross-protective control strategy against these troublesome pathogens and paves the way for the development of a safe and effective vaccine. IMPORTANCE Klebsiella pneumoniae is an opportunistic Gram-negative bacterium that has become a leading causative agent of nosocomial infections. Among the numerous capsular serotypes, K1, K2, K47, and K64 are commonly associated with higher virulence (hypervirulent K. pneumoniae). More threateningly, the last two serotypes are frequently associated with resistance to carbapenem (hypervirulent carbapenem-resistant K. pneumoniae). However, there is currently no therapeutic agent or vaccine specifically against these isolates. Therefore, development of a vaccine against these pathogens is very essential. In this study, for the first time, a method combining pangenome analysis, reverse vaccinology, and immunoinformatics was applied for contriving a multiepitope subunit vaccine against K. pneumoniae isolates of K1, K2, K47, and K64. Also, the immunological properties of the constructed vaccine were evaluated and its high potency was revealed. Overall, our research will pave the way for the vaccine development against these four threatening capsular serotypes of K. pneumoniae.
| S-EPMC9431259 | biostudies-literature