scholarly journals Cloning of the Staphylococcus aureus ddh gene encoding NAD+-dependent D-lactate dehydrogenase and insertional inactivation in a glycopeptide-resistant isolate.

1997 ◽  
Vol 179 (21) ◽  
pp. 6756-6763 ◽  
Author(s):  
S Boyle-Vavra ◽  
B L de Jonge ◽  
C C Ebert ◽  
R S Daum
Keyword(s):  
Staphylococcus Aureus ◽  
Lactate Dehydrogenase ◽  
Resistant Isolate ◽  
Gene Encoding ◽  
Insertional Inactivation

scholarly journals Loss of Function of the GdpP Protein Leads to Joint β-Lactam/Glycopeptide Tolerance in Staphylococcus aureus

2011 ◽  
Vol 56 (1) ◽  
pp. 579-581 ◽  
Author(s):  
J. M. Griffiths ◽  
A. J. O'Neill
Keyword(s):  
Signal Transduction ◽  
Staphylococcus Aureus ◽  
Genome Sequencing ◽  
Genetic Basis ◽  
Loss Of Function ◽  
Gene Encoding ◽  
Content Type ◽  
Peptidoglycan Biosynthesis ◽  
Insertional Inactivation

ABSTRACTThe genetic basis of tolerance to inhibitors of peptidoglycan biosynthesis inStaphylococcus aureuswas investigated by generating tolerant mutantsin vitroand characterizing them by comparative genome sequencing. Two independently selected tolerant mutants harbored nonsynonymous mutations ingdpP, a gene encoding a putative membrane-located signaling protein. Insertional inactivation ofgdpPalso conferred tolerance. Our findings further implicate altered signal transduction as a route to antibiotic tolerance inS. aureus.

scholarly journals Overproduction of a 37-kilodalton cytoplasmic protein homologous to NAD+-linked D-lactate dehydrogenase associated with vancomycin resistance in Staphylococcus aureus.

1996 ◽  
Vol 40 (1) ◽  
pp. 166-172 ◽  
Author(s):  
W M Milewski ◽  
S Boyle-Vavra ◽  
B Moreira ◽  
C C Ebert ◽  
R S Daum
Keyword(s):  
Staphylococcus Aureus ◽  
Lactate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Vancomycin Resistance ◽  
Nucleotide Sequencing ◽  
Cytoplasmic Protein ◽  
Degenerate Primers ◽  
Gene Encoding ◽  
Lactate Dehydrogenase Activity ◽  
Pcr Product

We previously reported the isolation of a laboratory-derived Staphylococcus aureus mutant, 523k, that has constitutive low-level resistance to vancomycin (MIC = 5 micrograms/ml) and teicoplanin (MIC = 5 micrograms/ml) and elaborates a ca. 39-kDa cytoplasmic protein that was not detected in the parent strain 523 (MIC = 1 micrograms/ml). We have now detected the protein in strain 523 by immunoblotting with antiserum raised against the protein. Consistent with our initial observations, densitometric analysis of the immunoblots revealed an increased production of the protein in 523k compared with that of the susceptible parent 523. The 5' region of the gene encoding the protein of interest was identified by nucleotide sequencing a PCR product amplified from the genome of 523k with degenerate primers designed to encode the amino acid sequence of proteolytic peptides obtained from the protein. The remainder of the gene was identified by library screening, PCR, and nucleotide sequencing. The gene encodes a 36.7-kDa protein with homology to a family of bacterial NAD+-dependent, D-specific 2-hydroxyacid dehydrogenases which includes both D-lactate dehydrogenase and the enterococcal vancomycin resistance protein VanH and is therefore designated ddh. Increased production of the product of ddh, Ddh, was associated with increased D-lactate dehydrogenase activity in 523k, a finding which suggested that Ddh is likely to be the D-lactate dehydrogenase previously identified in S. aureus. The increased D-lactate dehydrogenase activity in strain 523k and the structural similarities among Ddh, D-lactate dehydrogenase, and VanH suggest that overproduction of Ddh might play a role in vancomycin resistance in this strain.

scholarly journals The AbcA Transporter of Staphylococcus aureus Affects Cell Autolysis

2001 ◽  
Vol 45 (2) ◽  
pp. 407-412 ◽  
Author(s):  
Gesine Schrader-Fischer ◽  
Brigitte Berger-Bächi
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistance ◽  
Erythromycin Resistance ◽  
Gene Encoding ◽  
Transcription Analysis ◽  
Global Regulators ◽  
Cell Extracts ◽  
Insertional Inactivation ◽  
Cell Autolysis

ABSTRACT Increased production of penicillin-binding protein PBP 4 is known to increase peptidoglycan cross-linking and contributes to methicillin resistance in Staphylococcus aureus. The pbp4gene shares a 400-nucleotide intercistronic region with the divergently transcribed abcA gene, encoding an ATP-binding cassette transporter of unknown function. Our study revealed that methicillin stimulated abcA transcription but had no effects onpbp4 transcription. Analysis of abcA expression in mutants defective for global regulators showed that abcAis under the control of agr. Insertional inactivation ofabcA by an erythromycin resistance determinant did not influence pbp4 transcription, nor did it alter resistance to methicillin and other cell wall-directed antibiotics. However,abcA mutants showed spontaneous partial lysis on plates containing subinhibitory concentrations of methicillin due to increased spontaneous autolysis. Since the autolytic zymograms of cell extracts were identical in mutants and parental strains, we postulate an indirect role of AbcA in control of autolytic activities and in protection of the cells against methicillin.

Phylogeny Characterization of Seb Gene Encoding Enterotoxins in Staphylococcus aureus Isolated from Raw Milk and Cheese

2019 ◽  
Vol 9 (o3) ◽  
Author(s):  
Fatima N. Aziz ◽  
Laith Abdul Hassan Mohammed-Jawad
Keyword(s):  
Staphylococcus Aureus ◽  
Food Poisoning ◽  
Raw Milk ◽  
Staphylococcal Enterotoxin B ◽  
Human Pathogen ◽  
Conventional Pcr ◽  
Biochemical Tests ◽  
Specific Primers ◽  
Gene Encoding

Food poisoning due to the bacteria is a big global problem in economically and human's health. This problem refers to an illness which is due to infection or the toxin exists in nature and the food that use. Milk is considered a nutritious food because it contains proteins and vitamins. The aim of this study is to detect and phylogeny characterization of staphylococcal enterotoxin B gene (Seb). A total of 200 milk and cheese samples were screened. One hundred ten isolates of Staphylococcus aureus pre-confirmed using selective and differential media with biochemical tests. Genomic DNA was extracted from the isolates and the SEB gene detects using conventional PCR with specific primers. Three staphylococcus aureus isolates were found to be positive for Seb gene using PCR and confirmed by sequencing. Sequence homology showed variety range of identity starting from (100% to 38%). Phylogenetic tree analyses show that samples (6 and 5) are correlated with S. epidermidis. This study discovered that isolates (A6-RLQ and A5-RLQ) are significantly clustered in a group with non- human pathogen Staphylococcus agnetis.

scholarly journals The Prevalence of Virulence Determinants and Antibiotic Resistance Patterns in Methicillin—Resistant Staphylococcus aureus in a Nursing Home in Poland

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 427
Author(s):  
Martyna Kasela ◽  
Agnieszka Grzegorczyk ◽  
Bożena Nowakowicz-Dębek ◽  
Anna Malm
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Variable Number Tandem Repeat ◽  
Multidrug Resistant ◽  
Variable Number ◽  
Pulse Field ◽  
Virulence Determinants ◽  
Gene Encoding ◽  
Methicillin Resistant ◽  
Pulse Field Gel Electrophoresis

Nursing homes (NH) contribute to the regional spread of methicillin-resistant Staphylococcus aureus (MRSA). Moreover, residents are vulnerable to the colonization and subsequent infection of MRSA etiology. We aimed at investigating the molecular and phenotypic characteristics of 21 MRSA collected from the residents and personnel in an NH (Lublin, Poland) during 2018. All MRSA were screened for 20 genes encoding virulence determinants (sea-see, eta, etb, tst, lukS-F-PV, eno, cna, ebpS, fib, bbp, fnbA, fnbB, icaADBC) and for resistance to 18 antimicrobials. To establish the relatedness and clonal complexes of MRSA in NH we applied multiple-locus variable-number tandem-repeat fingerprinting (MLVF), pulse field gel electrophoresis (PFGE), multilocus sequence typing (MLST) and staphylococcal cassette chromosome mec (SCCmec) typing. We identified four sequence types (ST) among two clonal complexes (CC): ST (CC22) known as EMRSA-15 as well as three novel STs—ST6295 (CC8), ST6293 (CC8) and ST6294. All tested MRSA were negative for sec, eta, etb, lukS-F-PV, bbp and ebpS genes. The most prevalent gene encoding toxin was sed (52.4%; n = 11/21), and adhesins were eno and fnbA (100%). Only 9.5% (n = 2/21) of MRSA were classified as multidrug-resistant. The emergence of novel MRSA with a unique virulence and the presence of epidemic clone EMRSA-15 creates challenges for controlling the spread of MRSA in NH.

scholarly journals The ldhA Gene Encoding Fermentative L-Lactate Dehydrogenase in Corynebacterium glutamicum Is Positively Regulated by the Global Regulator GlxR

2021 ◽  
Vol 9 (3) ◽  
pp. 550
Author(s):  
Koichi Toyoda ◽  
Masayuki Inui
Keyword(s):  
Lactate Dehydrogenase ◽  
Binding Site ◽  
Corynebacterium Glutamicum ◽  
Lactate Production ◽  
Exponential Phase ◽  
Aerobic Bacterium ◽  
Global Regulator ◽  
Gene Encoding ◽  
Fermentation Products ◽  
Ldha Gene

Bacterial metabolism shifts from aerobic respiration to fermentation at the transition from exponential to stationary growth phases in response to limited oxygen availability. Corynebacterium glutamicum, a Gram-positive, facultative aerobic bacterium used for industrial amino acid production, excretes L-lactate, acetate, and succinate as fermentation products. The ldhA gene encoding L-lactate dehydrogenase is solely responsible for L-lactate production. Its expression is repressed at the exponential phase and prominently induced at the transition phase. ldhA is transcriptionally repressed by the sugar-phosphate-responsive regulator SugR and L-lactate-responsive regulator LldR. Although ldhA expression is derepressed even at the exponential phase in the sugR and lldR double deletion mutant, a further increase in its expression is still observed at the stationary phase, implicating the action of additional transcription regulators. In this study, involvement of the cAMP receptor protein-type global regulator GlxR in the regulation of ldhA expression was investigated. The GlxR-binding site found in the ldhA promoter was modified to inhibit or enhance binding of GlxR. The ldhA promoter activity and expression of ldhA were altered in proportion to the binding affinity of GlxR. Similarly, L-lactate production was also affected by the binding site modification. Thus, GlxR was demonstrated to act as a transcriptional activator of ldhA.

scholarly journals Antagonism between Aminoglycosides and β-Lactams in a Methicillin-Resistant Staphylococcus aureus Isolate Involves Induction of an Aminoglycoside-Modifying Enzyme

2002 ◽  
Vol 46 (5) ◽  
pp. 1516-1521 ◽  
Author(s):  
Takashi Ida ◽  
Ryoichi Okamoto ◽  
Masato Nonoyama ◽  
Kazuhiko Irinoda ◽  
Mizuyo Kurazono ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Antimicrobial Activities ◽  
Hybrid Structure ◽  
Conjugative Plasmid ◽  
Pcr Analysis ◽  
Aminoglycoside Resistance ◽  
Gene Encoding ◽  
Methicillin Resistant ◽  
Aureus Isolate

ABSTRACT We encountered three clinical isolates of methicillin-resistant Staphylococcus aureus which were susceptible to netilmicin and arbekacin in the absence of β-lactam antibiotics but which were resistant to them in the presence of β-lactam antibiotics. One of these strains, KU5801, was used to further investigate the antagonism between aminoglycosides and β-lactam antibiotics. β-Lactam antibiotics induced bacterial synthesis of aminoglycoside-6′-N-acetyltransferase and 2"-O-phosphotransferase [AAC(6′)-APH(2")] in association with decreased antimicrobial activities of aminoglycosides. A 14.4-kb EcoRI fragment that included the genes that control for β-lactam-inducible aminoglycoside resistance was cloned from a 31-kb conjugative plasmid present in KU5801. Restriction fragment mapping and PCR analysis suggested that a Tn4001-like element containing a gene encoding AAC(6′)-APH(2") was located downstream from a truncated blaZ gene. The DNA sequence between blaR1 and a Tn4001-like element was determined. The Tn4001-IS257 hybrid structure was cointegrated into the blaZ gene, and the typical sequences for the termination of transcription were not found between these regions. We deduced that antagonism of aminoglycosides by β-lactam antibiotics in isolate KU5801 involved transcription of the aac(6′)-Ie-aph(2")-Ia gene under the influence of the system regulating penicillinase production.

scholarly journals A K+ Uptake Protein, TrkA, Is Required for Serum, Protamine, and Polymyxin B Resistance in Vibrio vulnificus

2004 ◽  
Vol 72 (2) ◽  
pp. 629-636 ◽  
Author(s):  
Yu-Chung Chen ◽  
Yin-Ching Chuang ◽  
Chun-Chin Chang ◽  
Chii-Ling Jeang ◽  
Ming-Chung Chang
Keyword(s):  
Human Serum ◽  
Vibrio Vulnificus ◽  
Polymyxin B ◽  
Wild Type ◽  
Gene Encoding ◽  
Reading Frame ◽  
Isogenic Mutant ◽  
Virulence Attenuation ◽  
Insertional Inactivation ◽  
Transposon Mutants

ABSTRACT Vibrio vulnificus, a highly virulent marine bacterium, is the causative agent of both serious wound infections and fatal septicemia in many areas of the world. To identify the genes required for resistance to human serum, we constructed a library of transposon mutants of V. vulnificus and screened them for hypersensitivity to human serum. Here we report that one of the isolated serum-susceptible mutants had a mutation in an open reading frame identified as trkA, a gene encoding an amino acid sequence showing high identity to that of TrkA of Vibrio alginolyticus, a protein required for the uptake of potassium. A trkA isogenic mutant was constructed via insertional inactivation, and it was significantly more easily killed by human serum, protamine, or polymyxin B than was the wild type. At K+ concentrations of 1 to 20 mM, this isogenic mutant showed attenuated growth compared to the wild-type strain. In addition, infection experiments demonstrated virulence attenuation when this mutant was administered intraperitoneally or subcutaneously to both normal and iron-treated mice, indicating that TrkA may modulate the transport of potassium and resistance to host innate defenses and that it is important for virulence in mice.

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