scholarly journals Virulence Determinants of Colistin-Resistant K. pneumoniae High-Risk Clones

Biology ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 436
Author(s):  
Ozlem Dogan ◽  
Cansel Vatansever ◽  
Nazli Atac ◽  
Ozgur Albayrak ◽  
Sercin Karahuseyinoglu ◽  
...  
Keyword(s):  
High Risk ◽  
Virulence Factors ◽  
Median Survival ◽  
Iron Uptake ◽  
Virulence Genes ◽  
Virulence Determinants ◽  
Neutrophil Activity ◽  
Biosynthesis Gene ◽  
Survival Capacity ◽  
Neutrophil Response

We proposed the hypothesis that high-risk clones of colistin-resistant K. pneumoniae (ColR-Kp) possesses a high number of virulence factors and has enhanced survival capacity against the neutrophil activity. We studied virulence genes of ColR-Kp isolates and neutrophil response in 142 patients with invasive ColR-Kp infections. The ST101 and ST395 ColR-Kp infections had higher 30-day mortality (58%, p = 0.005 and 75%, p = 0.003). The presence of yersiniabactin biosynthesis gene (ybtS) and ferric uptake operon associated gene (kfu) were significantly higher in ST101 (99%, p ≤ 0.001) and ST395 (94%, p < 0.012). Being in ICU (OR: 7.9; CI: 1.43–55.98; p = 0.024), kfu (OR:27.0; CI: 5.67–179.65; p < 0.001) and ST101 (OR: 17.2; CI: 2.45–350.40; p = 0.01) were found to be predictors of 30-day mortality. Even the neutrophil uptake of kfu+-ybtS+ ColR-Kp was significantly higher than kfu--ybtS- ColR-Kp (phagocytosis rate: 78% vs. 65%, p < 0.001), and the kfu+-ybtS+ ColR-Kp survived more than kfu--ybtS- ColR-Kp (median survival index: 7.90 vs. 4.22; p = 0.001). The kfu+-ybtS+ ColR-Kp stimulated excessive NET formation. Iron uptake systems in high-risk clones of colistin-resistant K. pneumoniae enhance the success of survival against the neutrophil phagocytic defense and stimulate excessive NET formation. The drugs targeted to iron uptake systems would be a promising approach for the treatment of colistin-resistant high-risk clones of K. pneumoniae infections.

scholarly journals The role of iron uptake systems in the pathogenesis of colistin-resistant hypervirulent K.pneumoniae infections

2019 ◽  
Author(s):  
Ozlem Dogan ◽  
Cansel Vatansever ◽  
Nazli Atac ◽  
Ozgur Albayrak ◽  
Sercin Karahuseyinoglu ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Iron Uptake ◽  
Virulence Genes ◽  
Killing Activity ◽  
Neutrophil Activity ◽  
Biosynthesis Gene ◽  
Survival Capacity ◽  
Invasive Infections ◽  
Neutrophil Response

SummaryHere we proposed the hypothesis that hypervirulent colistin resistant K.pneumoniae (ColR-Kp) exhibit high number of virulence factors and have enhanced survival capacity against neutrophil activity.We studied virulence genes of ColR-Kp isolates and neutrophil response in 142 patients with invasive infections.The patients infected with hypervirulent ST101 and ST395 ColR-Kp had higher 30-day mortality (58%, p=0.005 and 75%, p=0.003, respectively. The yersiniabactin biosynthesis gene (ybtS) and ferric uptake operon associated gene (kfu) were significantly higher in ST101 (99%, p=<0.001) and in ST395 (94%, p<0.012). Being in ICU (OR: 7.9; CI: 1.43-55.98; p=0.024), kfu (OR:27.0; CI:5.67-179.65; p<0.001) and ST101 (OR: 17.2; CI: 2.45-350.40; p=0.01) were found to be predictors of 30-day mortality. The uptake of kfu+-ybtS+ ColR-Kp by neutrophils was significantly higher than kfu--ybtS- ColR-Kp (78% vs 65%, p<0.001). However, kfu+-ybtS+ ColR-Kp were more resistant to the killing activity of neutrophils than negative ones (7.90 vs 4.22; p=0.001). The kfu+-ybtS+ ColR-Kp stimulated excessive NET formation while the NET’s against kfu--ybtS- ColR-Kp were weak and rare.Iron uptake systems enhance successful survival of K.pneumoniae against neutrophil phagocytic defense, and stimulate excessive NET formation. The drugs targeted to iron uptake systems would be a promising approach for treatment of hypervirulent K.pneumoniae infections.

Use of virulence determinants and seropathotypes to distinguish high- and low-riskEscherichia coliO157 and non-O157 isolates from Europe

2013 ◽  
Vol 142 (5) ◽  
pp. 1019-1028 ◽  
Author(s):  
M. F. ANJUM ◽  
E. JONES ◽  
V. MORRISON ◽  
R. TOZZOLI ◽  
S. MORABITO ◽  
...  
Keyword(s):  
High Risk ◽  
Gel Electrophoresis ◽  
Virulence Genes ◽  
Pulsed Field Gel Electrophoresis ◽  
Virulence Determinants ◽  
Chain Reaction ◽  
E Coli ◽  
Specific Pcr ◽  
Polymerase Chain ◽  
Production Strain

SUMMARYThe presence of 10 virulence genes was examined using polymerase chain reaction (PCR) in 365 European O157 and non-O157Escherichia coliisolates associated with verotoxin production. Strain-specific PCR data were analysed using hierarchical clustering. The resulting dendrogram clearly separated O157 from non-O157 strains. The former clustered typical high-risk seropathotype (SPT) A strains from all regions, including Sweden and Spain, which were homogenous by Cramer'sVstatistic, and strains with less typical O157 features mostly from Hungary. The non-O157 strains divided into a high-risk SPTB harbouring O26, O111 and O103 strains, a group pathogenic to pigs, and a group with few virulence genes other than for verotoxin. The data demonstrate SPT designation and selected PCR separated verotoxigenicE. coliof high and low risk to humans; although more virulence genes or pulsed-field gel electrophoresis will need to be included to separate high-risk strains further for epidemiological tracing.

Genes Encoding Bacteriocins and Their Expression and Potential Virulence Factors of Enterococci Isolated from Wood Pigeons (Columba palumbus)

2006 ◽  
Vol 69 (3) ◽  
pp. 520-531 ◽  
Author(s):  
MARÍA MARTÍN ◽  
JORGE GUTIÉRREZ ◽  
RAQUEL CRIADO ◽  
CARMEN HERRANZ ◽  
LUIS M. CINTAS ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Virulence Factors ◽  
Virulence Genes ◽  
Pcr Amplification ◽  
Virulence Gene ◽  
Antagonistic Activity ◽  
Mass Spectrometry Analysis ◽  
Enzyme Linked Immunosorbent Assay ◽  
Virulence Determinants ◽  
Spectrometry Analysis

Samples of the intestinal content and carcasses of wood pigeons (Columba palumbus) were evaluated for enterococci with antimicrobial activity. Enterococcus faecium comprised the largest enterococcal species with antagonistic activity, followed by Enterococcus faecalis and Enterococcus columbae. PCR amplification of genes coding bacteriocins and determination of their nucleotide sequence, and the use of specific antipeptide bacteriocin antibodies and a noncompetitive indirect enzyme-linked immunosorbent assay, permitted characterization of enterococci coding that described bacteriocins and their expression. The efaAfm determinant was the only virulence gene detected in E. faecium, whereas E. faecalis showed a larger number of virulence determinants, and E. columbae did not carry any of the virulence genes examined. Although all E. faecalis isolates manifested a potent direct antimicrobial activity, no activity was detected in supernatants of producer cells. Purification of the antagonistic activity of E. columbae PLCH2 showed multiple chromatographic fragments after matrix-assisted laser desorption–ionization time-of-flight mass spectrometry analysis, suggesting the active peptide(s) had not yet purified to homogeneity. Bacteriocinogenic E. faecium and E. columbae isolates may be considered hygienic for production of enterocins and potentially safe due to their low incidence of potential virulence genes and susceptibility of most relevant clinical antibiotics. However, the presence among the enterococci of E. faecalis strains with a potent antagonistic activity and multiple virulence factors is an issue that must be considered further.

scholarly journals Enterococcus faecium isolated from healthy dogs for potential use as probiotics

2020 ◽  
Vol 23 (2) ◽  
pp. 197-205
Author(s):  
K. A. Abd El-Razik ◽  
E. S. Ibrahim ◽  
A. M. Younes ◽  
A. A. Arafa ◽  
A. S. M. Abuelnaga ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Molecular Identification ◽  
Enterococcus Faecium ◽  
Virulence Genes ◽  
Pcr Amplification ◽  
Virulence Determinants ◽  
Specific Pcr ◽  
Healthy Dogs ◽  
Potential Use

This study aimed to isolate and identify enterococci obtained from fresh faecal swabs of 16 healthy dogs. Following molecular identification, all isolates were screened against the most critical virulence factors as well as enterocin (bacteriocin) determinants to confirm that the isolated enterococcus was safe to be used as host-specific probiotic. Enterococcus faecium was isolated and confirmed in 8 out of the 16 samples. Regarding the assessment of the virulence determinants, E. faecium strains were negative for tested (gelE and esp) virulence genes. Furthermore, the genome was evaluated for the incidence of five known enterocin genes by specific PCR amplification. Four strains encoding entAS-48 gene were found, while only one strain harboured the entL50A/B gene. Based on these results, five of the E. faecium isolated in this study were considered as promising probiotic candidates for dogs.

scholarly journals Silkworm model for Bacillus anthracis infection and virulence determination

2021 ◽  
Author(s):  
Atmika Paudel ◽  
Yoshikazu Furuta ◽  
Hideaki Higashi
Keyword(s):  
Bacillus Anthracis ◽  
Virulence Factors ◽  
Large Scale ◽  
Virulence Genes ◽  
Lethal Dose ◽  
Infection Model ◽  
Virulence Determinants ◽  
Silkworm Hemolymph ◽  
Effective Doses ◽  
Obligate Pathogen

Bacillus anthracis is an obligate pathogen and a causative agent of anthrax. Its major virulence factors are plasmid-coded; however, recent studies have revealed chromosome-encoded virulence factors, indicating that the current understanding of its virulence mechanism is elusive and needs further investigation. In this study, we established a silkworm (Bombyx mori) infection model of B. anthracis Sterne. We showed that silkworms were killed by B. anthracis and cured of the infection when administered with antibiotics. We quantitatively determined the lethal dose of the bacteria that kills 50% larvae and effective doses of antibiotics that cure 50% infected larvae. Furthermore, we demonstrated that B. anthracis mutants with disruption in virulence genes such as pagA, lef, and atxA had attenuated silkworm-killing ability and reduced colonization in silkworm hemolymph. The silkworm infection model established in this study can be utilized in large-scale infection experiments to identify novel virulence determinants and develop novel therapeutic options against B. anthracis infections.

Virulence determinants and production of extracellular enzymes in Enterococcus spp. from surface water sources

2016 ◽  
Vol 73 (8) ◽  
pp. 1817-1824 ◽  
Author(s):  
Lesego Gertrude Molale ◽  
Cornelius Carlos Bezuidenhout
Keyword(s):  
Surface Water ◽  
Virulence Factors ◽  
Virulence Genes ◽  
Extracellular Enzymes ◽  
Virulence Gene ◽  
Water Sources ◽  
Virulence Determinants ◽  
North West ◽  
Enterococcus Spp

Virulence factors in Enterococcus may be indicative of potential pathogenicity. The aim of this study was to determine the relationship between the presence of clinically relevant virulence genes, in Enterococcus spp. from environmental water, and their in vitro expression. One hundred and twenty-four Enterococcus isolates (seven species), from five surface water systems in the North West Province, South Africa, were screened for the presence of asa1, cylA, esp, gelE and hyl using polymerase chain reaction. The expression of cylA, hyl and gelE was determined by phenotypic assessments. Sixty-five percent of the isolates were positive for one virulence gene and 13% for two or more. Most frequently detected genes were gelE (32%) and cylA (28%). Enterococcal surface protein was absent in all isolates screened. The presence of virulence genes was correlated with their extracellular enzyme production. The results show that a large percentage of these environmental Enterococcus spp. possess virulence factors that could be expressed in vitro. This is a cause for concern and could have implications for individuals using this water for recreational and cultural purposes. Further investigation is required into the sources of these potential pathogenic Enterococcus isolates and measures to minimize their presence in water sources.

scholarly journals Screening of virulence genes in Staphylococcus aureus isolates from rabbits

2015 ◽  
Vol 23 (3) ◽  
pp. 185 ◽  
Author(s):  
David Viana Martín ◽  
Laura Selva ◽  
Mariola Penadés ◽  
Juan Manuel Corpa
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Multilocus Sequence Typing ◽  
Virulence Genes ◽  
Bacterial Virulence ◽  
Virulence Determinants ◽  
Different Ages

<p><em>Staphylococcus aureus</em> is a versatile pathogen able to cause disease in both humans and animals. In rabbits, this bacterium infects animals of different ages, producing several purulent lesions. The ability of <em>S. aureus</em> to cause disease depends on a combination of virulence factors. The aim of this study was therefore to investigate the distribution of bacterial virulence determinants in 69 <em>S. aureus</em> isolates from rabbits. Some virulence factors (7 adhesins, 1 toxin and 1 protease) were positive in all rabbit <em>S. aureus</em> isolates analysed, while others (1 adhesin and 10 toxins) were always negative. The remaining virulence factors were more variable among isolates. An association between genotype and the different profiles of virulence factors was observed, but not with the type of lesion (P&lt;0.05). One strain of each genotype was further analysed by multilocus sequence typing, generating ST121, ST96 and ST2951, determining a greater number of enterotoxins in ST121 isolates compared to ST96 and ST2951 isolates, which could justify the different pathogenicity between strains. </p>

Enterococcal Virulence Determinants In Urinary Tract Infection Patients

2012 ◽  
Vol 6 (1) ◽  
pp. 14-17
Author(s):  
Jabin Akhter ◽  
Shaheda Anwar ◽  
Sharmeen Ahmed
Keyword(s):  
Urinary Tract Infection ◽  
Urinary Tract ◽  
Tract Infection ◽  
Virulence Factors ◽  
Virulence Determinants ◽  
Microtitre Plate ◽  
Microbiological Method ◽  
Enterococcal Infection ◽  
Microtitre Plate Assay ◽  
Positive Frequency

Urinary tract infection caused by Enterococci has become frequent occurrences in health care settings. Currently they emerged with increasing resistance to multiple antibiotics.  Haemolysin, gelatinase and biofilm production are some markers that have been proposed as possible Enterococcal virulence factors. In view of the increasing importance of Enterococcal infection, the present study was designed to isolate and identify the Enterococci to the species level from urine of urinary tract infection patients and to investigate their possible virulence factors. Biofilm was detected on polystyrene microtitre plate to see the adherence of microorganism. Haemolysin production and gelatin hydrolysis detected by standard microbiological method. Fifty nine enterococcal isolates were speciated by conventional microbiological method and examined for their ability to form biofilm by microtitre plate assay. In this study, biofilm formations by Enterococci were found in 83.33% isolates from catheterized and 56.09% from non-catheterized patients. Aong them, E.faecalis & 50% E.faecium produced biofilm. About 43.63% E.faecalis & 10% E.faecium produced haemolysin and only one isolate were found to be gelatinase positive. Frequency of virulence factors (VFs) in combination was observed in this study. Two VFs (haemolysin and biofilm) were observed in 27.11% in combination and 3 VFs ( haemolysinm biofilm and gelatinase) were present in 1.69% isolates. These results suggest that although there may not be an absolute role for individual virulence determinants in infectivity, combinations of factors may play a role in allowing a biofilm infection to be more resistant to therapy.DOI: http://dx.doi.org/10.3329/bjmm.v6i1.19361 Bangladesh J Med Microbiol 2012; 06(01): 14-17

scholarly journals Clonal Clusters, Molecular Resistance Mechanisms and Virulence Factors of Gram-Negative Bacteria Isolated from Chronic Wounds in Ghana

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 339
Author(s):  
Denise Dekker ◽  
Frederik Pankok ◽  
Thorsten Thye ◽  
Stefan Taudien ◽  
Kwabena Oppong ◽  
...  
Keyword(s):  
Molecular Epidemiology ◽  
Virulence Factors ◽  
Iron Uptake ◽  
Chronic Wounds ◽  
Sub Saharan Africa ◽  
Gram Negative Bacteria ◽  
Beta Lactamase ◽  
Secretion Systems ◽  
Gram Negative ◽  
E Coli

Wound infections are common medical problems in sub-Saharan Africa but data on the molecular epidemiology are rare. Within this study we assessed the clonal lineages, resistance genes and virulence factors of Gram-negative bacteria isolated from Ghanaian patients with chronic wounds. From a previous study, 49 Pseudomonas aeruginosa, 21 Klebsiellapneumoniae complex members and 12 Escherichia coli were subjected to whole genome sequencing. Sequence analysis indicated high clonal diversity with only nine P. aeruginosa clusters comprising two strains each and one E. coli cluster comprising three strains with high phylogenetic relationship suggesting nosocomial transmission. Acquired beta-lactamase genes were observed in some isolates next to a broad spectrum of additional genetic resistance determinants. Phenotypical expression of extended-spectrum beta-lactamase activity in the Enterobacterales was associated with blaCTX-M-15 genes, which are frequent in Ghana. Frequently recorded virulence genes comprised genes related to invasion and iron-uptake in E. coli, genes related to adherence, iron-uptake, secretion systems and antiphagocytosis in P. aeruginosa and genes related to adherence, biofilm formation, immune evasion, iron-uptake and secretion systems in K. pneumonia complex. In summary, the study provides a piece in the puzzle of the molecular epidemiology of Gram-negative bacteria in chronic wounds in rural Ghana.

scholarly journals Burden, Antibiotic Resistance, and Clonality of Shigella spp. Implicated in Community-Acquired Acute Diarrhoea in Lilongwe, Malawi

2021 ◽  
Vol 6 (2) ◽  
pp. 63
Author(s):  
Abel F.N.D. Phiri ◽  
Akebe Luther King Abia ◽  
Daniel Gyamfi Amoako ◽  
Rajab Mkakosya ◽  
Arnfinn Sundsfjord ◽  
...  
Keyword(s):  
Real Time ◽  
Antibiotic Susceptibility ◽  
Virulence Genes ◽  
Shigella Flexneri ◽  
Acute Diarrhoea ◽  
Virulence Determinants ◽  
African Countries ◽  
Shigella Species ◽  
Shigella Spp ◽  
Sub Saharan

Although numerous studies have investigated diarrhoea aetiology in many sub-Saharan African countries, recent data on Shigella species’ involvement in community-acquired acute diarrhoea (CA-AD) in Malawi are scarce. This study investigated the incidence, antibiotic susceptibility profile, genotypic characteristics, and clonal relationships of Shigella flexneri among 243 patients presenting with acute diarrhoea at a District Hospital in Lilongwe, Malawi. Shigella spp. were isolated and identified using standard microbiological and serological methods and confirmed by identifying the ipaH gene using real-time polymerase chain reaction. The isolates’ antibiotic susceptibility to 20 antibiotics was determined using the VITEK 2 system according to EUCAST guidelines. Genes conferring resistance to sulfamethoxazole (sul1, sul2 and sul3), trimethoprim (dfrA1, dfrA12 and dfrA17) and ampicillin (oxa-1 and oxa-2), and virulence genes (ipaBCD, sat, ial, virA, sen, set1A and set1B) were detected by real-time PCR. Clonal relatedness was assessed using ERIC-PCR. Thirty-four Shigella flexneri isolates were isolated (an overall incidence of 14.0%). All the isolates were fully resistant to sulfamethoxazole/trimethoprim (100%) and ampicillin (100%) but susceptible to the other antibiotics tested. The sul1 (79%), sul2 (79%), sul3 (47%), dfrA12 (71%) and dfrA17 (56%) sulfonamide and trimethoprim resistance genes were identified; Oxa-1, oxa-2 and dfrA1 were not detected. The virulence genes ipaBCD (85%), sat (85%), ial (82%), virA (76%), sen (71%), stx (71%), set1A (26%) and set1B (18%) were detected. ERIC-PCR profiling revealed that the Shigella isolates were genetically distinct and clonally unrelated, indicating the potential involvement of genetically distinct S. flexneri in CA-AD in Malawi. The high percentage resistance to ampicillin and sulfamethoxazole/trimethoprim and the presence of several virulence determinants in these isolates emphasises a need for continuous molecular surveillance studies to inform preventive measures and management of Shigella-associated diarrhoeal infections in Malawi.

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