scholarly journals Staphylococcus aureusClinical Isolates: Antibiotic Susceptibility, Molecular Characteristics, and Ability to Form Biofilm

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
N. Indrawattana ◽  
O. Sungkhachat ◽  
N. Sookrung ◽  
M. Chongsa-nguan ◽  
A. Tungtrongchitr ◽  
...  
Keyword(s):  
Early Recognition ◽  
Clinical Isolates ◽  
Resistant Bacteria ◽  
Molecular Characteristics ◽  
Toxin Gene ◽  
Accessory Gene ◽  
Toxin Genes ◽  
Accessory Gene Regulator ◽  
Periodic Monitoring ◽  
Group 2

Periodic monitoring ofStaphylococcus aureuscharacteristics in a locality is imperative as their drug-resistant variants cause treatment problem. In this study, antibiograms, prevalence of toxin genes (sea-see, seg-ser, seu, tsst-1, eta, etb, andetd), PFGE types, accessory gene regulator (agr) groups, and ability to form biofilm of 92S. aureusThailand clinical isolates were investigated. They were classified into 10 drug groups: groups 1–7 (56 isolates) were methicillin resistant (MRSA) and 8–10 (36 isolates) were methicillin sensitive (MSSA). One isolate did not have any toxin gene, 4 isolates carried one toxin gene (seq), and 87 isolates had two or more toxin genes. No isolate hadsee, etb, ortsst-1; six isolates hadetaoretd. Combinedseg-sei-sem-sen-seoof the highly prevalentegclocus was 26.1%. Theseb, sec, sel, seu, andetaassociated significantly with MSSA;sekwas more in MRSA. Thesek-seqassociation was 52.17% while combinedsed-sejwas not found. Twenty-three PFGE types were revealed, no association of toxin genes with PFGE types. All fouragrgroups were present;agrgroup 1 was predominant (58.70%) butagrgroup 2 strains carried more toxin genes and were more frequent toxin producers. Biofilm formation was found in 72.83% of the isolates but there was no association with antibiograms. This study provides insight information on molecular and phenotypic markers of ThailandS. aureusclinical isolates which should be useful for future active surveillance that aimed to control a spread of existing antimicrobial resistant bacteria and early recognition of a newly emerged variant.

scholarly journals Population Studies of Methicillin-Resistant and -Sensitive Staphylococcus aureus Strains Reveal a Lack of Variability in the agrD Gene, Encoding a Staphylococcal Autoinducer Peptide

2000 ◽  
Vol 182 (20) ◽  
pp. 5721-5729 ◽  
Author(s):  
Willem van Leeuwen ◽  
Wendy van Nieuwenhuizen ◽  
Christel Gijzen ◽  
Henri Verbrugh ◽  
Alex van Belkum
Keyword(s):  
Staphylococcus Aureus ◽  
Accessory Gene ◽  
Gene Encoding ◽  
Methicillin Resistant ◽  
Accessory Gene Regulator ◽  
Colonization Dynamics ◽  
Group 2 ◽  
Bacterial Interference ◽  
Different Levels ◽  
Group 1

ABSTRACT The virulence of Staphylococcus aureus is controlled by the accessory gene regulator (agr) system, including an extracellular inducer encoded by agrD. Variableagr PCR restriction fragment length polymorphism (RFLP) patterns of unique S. aureus strains (n = 192) were determined for a region comprising agrD and parts of the neighboring agrC and agrB genes. Twelve unique RFLP patterns were identified among S. aureusstrains in general; these patterns were further specified by sequencing. All sequences could be catalogued in the three currentagr groups. A major proportion of the S. aureusstrains belong to agr group 1, whereas only 6% of the methicillin-susceptible S. aureus strains and 5% of the methicillin-resistant S. aureus strains belong toagr groups 2 and 3, respectively. The homology between groups varied from 75 to 80%, and within groups it varied from 96 to 100%. Different levels of sequence variability were observed in the different agr genes. agr-related bacterial interference among colonizing S. aureus strains in the noses of persistent and intermittent human carriers was studied.S. aureus strains belonging to different agr groups were encountered in the same individual. This may suggest that the activity of the agrD gene product does not define colonization dynamics, which is further substantiated by the rarity ofagr group 2 and 3 strains.

Superantigen gene profiles and presence of exfoliative toxin genes in community-acquired meticillin-resistant Staphylococcus aureus isolated from Chinese children

2011 ◽  
Vol 60 (1) ◽  
pp. 35-45 ◽  
Author(s):  
Dejing Wu ◽  
Xiangmei Li ◽  
Yonghong Yang ◽  
Yaojie Zheng ◽  
Chuanqing Wang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Genetic Background ◽  
Current Knowledge ◽  
Chinese Children ◽  
Toxin Gene ◽  
Virulence Determinants ◽  
Accessory Gene ◽  
Exfoliative Toxin ◽  
Toxin Genes ◽  
Gene Profiles

This study aimed to evaluate the distribution of superantigen gene profiles and the presence of exfoliative toxin genes in community-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA) isolated from Chinese children, and simultaneously to assess virulence gene profiles and genetic background. Of the CA-MRSA isolates, 88.9 % (88/99) harboured toxin genes, with sek as the most frequent toxin gene (62.6 %), followed by seq (61.6 %), seb (60.6 %) and sea (35.4 %). The eta gene was detected only in one ST398-IVa-spa t034 strain. The sed and etd genes were not found in any of the isolates tested. A total of 38 virulence genotypes were observed, of which the genotype seb-sek-seq (27.3 %, 24/88) comprised the majority, followed by sea-seb-sek-seq (18.2 %, 16/88). The enterotoxin gene cluster including seg-sei-sem-sen-seo-seu predominated at a rate of 15.1 %. The relationship among toxin genotypes, toxin genes encoding profiles of mobile genetic elements and genetic background was analysed. Among 66 clonal complex (CC) 59 isolates, 87.9 % (58/66) were positive for toxin genes, and 75.8 % (50/66) harboured the toxin gene combination seb-sek-seq. Among seb-sek-seq-positive CC59 strains, 42.0 % (21/50) also carried the sea gene. CC59 corresponded exclusively to accessory gene regulator 1 (agr-1). The data presented here enhance our current knowledge on the virulence determinants of CA-MRSA.

scholarly journals Mutation of traP in Staphylococcus aureus Has No Impact on Expression of agr or Biofilm Formation

2007 ◽  
Vol 75 (9) ◽  
pp. 4528-4533 ◽  
Author(s):  
Laura H. Tsang ◽  
Sonja T. Daily ◽  
Elizabeth C. Weiss ◽  
Mark S. Smeltzer
Keyword(s):  
Staphylococcus Aureus ◽  
Hemolytic Activity ◽  
Biofilm Formation ◽  
Laboratory Strain ◽  
Clinical Isolates ◽  
Regulatory Role ◽  
Accessory Gene ◽  
Accessory Gene Regulator ◽  
Affect Expression

ABSTRACT To investigate the regulatory role of traP (target of RNAIII-activating peptide) in Staphylococcus aureus, we generated traP mutations in the clinical isolates UAMS-1 and USA300. In neither case did mutation of traP affect expression of the accessory gene regulator (agr) or the ability to form a biofilm. We were also unable to confirm that mutation of traP in the prototype 8325-4 laboratory strain RN6390 results in reduced expression of agr, reduced hemolytic activity, or an altered capacity to form a biofilm.

scholarly journals Strain-Dependent Differences in the Regulatory Roles of sarA and agr in Staphylococcus aureus

2002 ◽  
Vol 70 (2) ◽  
pp. 470-480 ◽  
Author(s):  
Jon S. Blevins ◽  
Karen E. Beenken ◽  
Mohamed O. Elasri ◽  
Barry K. Hurlburt ◽  
Mark S. Smeltzer
Keyword(s):  
Staphylococcus Aureus ◽  
Opposite Effect ◽  
Laboratory Strain ◽  
Regulatory Elements ◽  
Growth Conditions ◽  
Lipase Production ◽  
Clinical Isolates ◽  
Slight Reduction ◽  
Accessory Gene ◽  
Accessory Gene Regulator

ABSTRACT The accessory gene regulator (agr) and the staphylococcal accessory regulator (sar) are central regulatory elements that control the production of Staphylococcus aureus virulence factors. To date, the functions of these loci have been defined almost exclusively using RN6390, which is representative of the laboratory strain 8325-4. However, RN6390 was recently shown to have a mutation in rsbU that results in a phenotype resembling that of a sigB mutant (I. Kullik et al., J. Bacteriol. 180:4814–4820, 1998). For that reason, it remains unclear whether the regulatory events defined in RN6390 are representative of the events that take place in clinical isolates of S. aureus. To address this issue, we generated mutations in the sarA and agr loci of three laboratory strains (RN6390, Newman, and S6C) and four clinical isolates (UAMS-1, UAMS-601, DB, and SC-1). Mutation of sarA in the cna-positive strains UAMS-1 and UAMS-601 resulted in an increased capacity to bind collagen, while mutation of agr had little impact. Northern blot analysis confirmed that the increase in collagen binding was due to increased cna transcription. Without exception, mutation of sarA resulted in increased production of proteases and a decreased capacity to bind fibronectin. Mutation of agr had the opposite effect. Although mutation of sarA resulted in a slight reduction in fnbA transcription, changes in the ability to bind fibronectin appeared to be more directly correlated with changes in protease activity. Lipase production was reduced in both sarA and agr mutants. While mutation of sarA in RN6390 resulted in reduced hemolytic activity, it had the opposite effect in all other strains. There appeared to be reduced levels of the sarC transcript in RN6390, but there was no difference in the overall pattern of sar transcription or the production of SarA. Although mutation of sarA resulted in decreased RNAIII transcription, this effect was not evident under all growth conditions. Taken together, these results suggest that studies defining the regulatory roles of sarA and agr by using RN6390 are not always representative of the events that occur in clinical isolates of S. aureus.

scholarly journals Prevalence and Genetic Diversity of Toxin Genes in Clinical Isolates of Clostridium perfringens: Coexistence of Alpha-Toxin Variant and Binary Enterotoxin Genes (bec/cpile)

Toxins ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 326 ◽  
Author(s):  
Asami Matsuda ◽  
Meiji Soe Aung ◽  
Noriko Urushibara ◽  
Mitsuyo Kawaguchiya ◽  
Ayako Sumi ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Clostridium Perfringens ◽  
Clinical Isolates ◽  
Nucleotide Sequencing ◽  
Toxin Gene ◽  
Alpha Toxin ◽  
Toxin Genes ◽  
Food Borne ◽  
Putative Origin ◽  
High Level

Clostridium perfringens (C. perfringens) is responsible for food-borne gastroenteritis and other infectious diseases, and toxins produced by this bacterium play a key role in pathogenesis. Although various toxins have been described for C. perfringens isolates from humans and animals, prevalence of individual toxins among clinical isolates has not yet been well explored. In the present study, a total of 798 C. perfringens clinical isolates were investigated for prevalence of eight toxin genes and their genetic diversity by PCR, nucleotide sequencing, and phylogenetic analysis. Besides the alpha-toxin gene (plc) present in all the isolates, the most common toxin gene was cpe (enterotoxin) (34.2%), followed by cpb2 (beta2 toxin) (1.4%), netB (NetB) (0.3%), and bec/cpile (binary enterotoxin BEC/CPILE) (0.1%), while beta-, epsilon-, and iota-toxin genes were not detected. Genetic analysis of toxin genes indicated a high level of conservation of plc, cpe, and netB. In contrast, cpb2 was revealed to be considerably divergent, containing at least two lineages. Alpha-toxin among 46 isolates was classified into ten sequence types, among which common types were distinct from those reported for avian isolates. A single isolate with bec/cpile harbored a plc variant containing an insertion of 834-bp sequence, suggesting its putative origin from chickens.

scholarly journals The Association of Molecular Characteristics, Vancomycin MIC and Clinical Outcomes in Methicillin-susceptible Staphylococcus aureus Osteoarticular Infections in Children

2017 ◽  
Vol 4 (suppl_1) ◽  
pp. S3-S3
Author(s):  
Jonathon McNeil ◽  
Jesus G Vallejo ◽  
Louie Rosas ◽  
Edward O Mason ◽  
Sheldon L Kaplan ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Clinical Outcomes ◽  
Disease Severity ◽  
Pathologic Fracture ◽  
Molecular Characteristics ◽  
Accessory Gene ◽  
Osteoarticular Infection ◽  
Accessory Gene Regulator ◽  
Group A

Abstract Background Methicillin-resistant Staphylococcus aureus, particularly those belonging to the USA300 pulsotype and bearing Panton–Valentine leucocidin (pvl), have been well described to cause severe osteoarticular infection (OAI). Vancomycin minimum inhibitory concentration (MIC) ≥ 1.5 µg/ml has been demonstrated to contribute to disease severity in MRSA bacteremia. Little data exist to describe the spectrum of outcomes in MSSA OAI in terms of molecular characteristics and vancomycin MIC. Methods OAI isolates were identified from 2011 to 2016 and subjected to vancomycin E-tests. MSSA isolates underwent PFGE, PCR for pvl, and a stepwise assay to determine accessory gene regulator (agr) group. A review of the medical record was performed. Orthopedic complications included chronic osteomyelitis, pathologic fracture, and growth arrest. Results During the study period, 167 cases of S. aureus OAI were identified; 115 were MSSA (68.9%). 29.1 and 26.1% of MSSA isolates were USA300 and pvl positive, respectively. USA300 isolates were more likely to be pvl-positive (66.7 vs. 13.6%, P < 0.001) and agr I (80% vs. 57.5%, P = 0.001). The presence of pvl was associated with agr I (P = 0.03), larger abscesses (6 vs. 2cm, P = 0.04), ICU admission (16.7 vs. 3.5%, P = 0.03) and a longer length of stay (11 vs. 6 days, P = 0.05). agr III and IV were associated with a higher rate of orthopedic complications (36.4 vs. 13.9%, P = 0.03) and surgical procedures (90.1 vs. 64.5%, P = 0.02) than other agr groups. An increase in the proportion of MSSA isolates with a vancomycin MIC ≥ 1.5 µg/ml occurred in the study period (P = 0.007, Figure 1). In MSSA, vancomycin MIC ≥ 2 µg/ml was associated with agr III (p = 0.07) and higher rates of orthopedic complications (P = 0.08) and venous thrombosis (P = 0.06, Figure 2). Conclusion MSSA accounts for 70% of S. aureus isolates causing OAI at TCH. While pvl-positive strains are associated with worse short-term outcomes, agr III and IV are associated with long-term morbidity. Vancomycin E-test MICs appear to be increasing among MSSA; vancomycin MIC ≥ 2 µg/ml are associated with agr-III and adverse clinical outcomes suggesting that this may be a surrogate for disease severity. Further work is needed to understand the contribution of these factors to invasive MSSA disease. Disclosures J. McNeil, NIAID, NIH: Grant Investigator, Grant recipient. 
S. L. Kaplan, Pfizer: Grant Investigator and Speaker at PCV13 Launch Meeting in China, Research grant and Speaker honorarium

scholarly journals Identification of Novel Toxin Genes from the Stinging Nettle Caterpillar Parasa lepida (Cramer, 1799): Insights into the Evolution of Lepidoptera Toxins

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 396
Author(s):  
Natrada Mitpuangchon ◽  
Kwan Nualcharoen ◽  
Singtoe Boonrotpong ◽  
Patamarerk Engsontia
Keyword(s):  
Protease Inhibitors ◽  
Proteolytic Enzymes ◽  
Gene Annotation ◽  
Sequence Similarity ◽  
New Drugs ◽  
Toxin Gene ◽  
Cone Snail ◽  
Stinging Nettle ◽  
Toxin Genes ◽  
Nettle Caterpillar

Many animal species can produce venom for defense, predation, and competition. The venom usually contains diverse peptide and protein toxins, including neurotoxins, proteolytic enzymes, protease inhibitors, and allergens. Some drugs for cancer, neurological disorders, and analgesics were developed based on animal toxin structures and functions. Several caterpillar species possess venoms that cause varying effects on humans both locally and systemically. However, toxins from only a few species have been investigated, limiting the full understanding of the Lepidoptera toxin diversity and evolution. We used the RNA-seq technique to identify toxin genes from the stinging nettle caterpillar, Parasa lepida (Cramer, 1799). We constructed a transcriptome from caterpillar urticating hairs and reported 34,968 unique transcripts. Using our toxin gene annotation pipeline, we identified 168 candidate toxin genes, including protease inhibitors, proteolytic enzymes, and allergens. The 21 P. lepida novel Knottin-like peptides, which do not show sequence similarity to any known peptide, have predicted 3D structures similar to tarantula, scorpion, and cone snail neurotoxins. We highlighted the importance of convergent evolution in the Lepidoptera toxin evolution and the possible mechanisms. This study opens a new path to understanding the hidden diversity of Lepidoptera toxins, which could be a fruitful source for developing new drugs.

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