Tetracycline Resistance Determinants in Gram-Positive Bacteria

2014 ◽  
pp. 801-820 ◽  
Author(s):  
Laura M. McMurry ◽  
Stuart B. Levy
Keyword(s):  
Tetracycline Resistance ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Resistance Determinants

scholarly journals Structural studies on the Clostridium perfringens conjugation system

2014 ◽  
Vol 70 (a1) ◽  
pp. C581-C581
Author(s):  
Von Torres ◽  
Jessica Wisniewski ◽  
Julian Rood ◽  
James Whisstock ◽  
Daouda Traore
Keyword(s):  
Clostridium Perfringens ◽  
Mobile Genetic Element ◽  
Tetracycline Resistance ◽  
Dna Transfer ◽  
Conjugation System ◽  
Membrane Channel ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Starting Point ◽  
Insight Into

Conjugation is the mechanism by which two bacteria share genetic information. This process relies on the direct transfer of mobile genetic element via a trans-membrane channel between the donor and the recipient. Although this mechanism has been extensively studied in gram-negative organism, very little in known on how this process takes place in their gram-positive counterpart. To address this important question in bacterial evolution, we use the tetracycline resistance plasmid pCW3 from Clostridium perfringens as study model. The pCW3 plasmid encodes 11 proteins necessary for the assembly the C. perfingens conjugation system. Here, I will focus on the relaxosome complex, which is the starting point of DNA transfer. We identified two protein (IntP and TcpK) involved in the processing of the DNA. Sequence analysis revealed that IntP was a potential Tyrosine recombinase and TcpK, directly upstream of IntP was identified a potential accessory protein of the relaxosome. We cloned, expressed and purified IntP and TcpK. These proteins were then subject to biochemical and biophysical characterizations. I will first present why these two proteins are required for efficient conjugative transfer and how they contribute to DNA processing. Then I will present the crystal structure of TcpK and discuss its interaction with IntP and other components of pCW3 apparatus. This study brings a further insight into this important mechanism of DNA transfer in Gram-positive bacteria.

scholarly journals Structure-Activity Relationship of the Aminomethylcyclines and the Discovery of Omadacycline

2015 ◽  
Vol 59 (11) ◽  
pp. 7044-7053 ◽  
Author(s):  
Laura Honeyman ◽  
Mohamed Ismail ◽  
Mark L. Nelson ◽  
Beena Bhatia ◽  
Todd E. Bowser ◽  
...  
Keyword(s):  
Tetracycline Resistance ◽  
Resistance Mechanisms ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
New Antibiotics ◽  
Protection Mechanisms ◽  
Relationship Of ◽  
Ribosomal Protection

ABSTRACTA series of novel tetracycline derivatives were synthesized with the goal of creating new antibiotics that would be unaffected by the known tetracycline resistance mechanisms. New C-9-position derivatives of minocycline (the aminomethylcyclines [AMCs]) were tested forin vitroactivity against Gram-positive strains containing known tetracycline resistance mechanisms of ribosomal protection (Tet M inStaphylococcus aureus,Enterococcus faecalis, andStreptococcus pneumoniae) and efflux (Tet K inS. aureusand Tet L inE. faecalis). A number of aminomethylcyclines with potentin vitroactivity (MIC range of ≤0.06 to 2.0 μg/ml) were identified. These novel tetracyclines were more active against one or more of the resistant strains than the reference antibiotics tested (MIC range, 16 to 64 μg/ml). The AMC derivatives were active against bacteria resistant to tetracycline by both efflux and ribosomal protection mechanisms. This study identified the AMCs as a novel class of antibiotics evolved from tetracycline that exhibit potent activityin vitroagainst tetracycline-resistant Gram-positive bacteria, including pathogenic strains of methicillin-resistantS. aureus(MRSA) and vancomycin-resistant enterococci (VRE). One derivative, 9-neopentylaminomethylminocycline (generic name omadacycline), was identified and is currently in human trials for acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP).

scholarly journals Preliminary Evaluation of the Research-Use-Only (RUO) iCubate iC-GPC Assay for Identification of Select Gram-Positive Bacteria and Their Resistance Determinants in Blood Culture Broths: TABLE 1

2015 ◽  
Vol 53 (12) ◽  
pp. 3931-3934 ◽  
Author(s):  
Blake W. Buchan ◽  
Garrett C. Reymann ◽  
Paul A. Granato ◽  
Brenda R. Alkins ◽  
Patricia Jim ◽  
...  
Keyword(s):  
Blood Culture ◽  
Staphylococcus Epidermidis ◽  
Bacterial Species ◽  
Genetic Resistance ◽  
Preliminary Evaluation ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Resistance Determinants ◽  
On Demand

The iC-GPC assay (iCubate, Huntsville, AL) provides a molecular option for the rapid, on-demand analysis of positive blood cultures. A preliminary evaluation of the iC-GPC assay using 203 clinical or seeded specimens demonstrated a sensitivity of 93.8% to 100% and a specificity of 98.0% to 100% for the identification of five Gram-positive bacterial species (Staphylococcus aureus,Staphylococcus epidermidis,Streptococcus pneumoniae,Enterococcus faecalis, andEnterococcus faecium) and three associated genetic resistance determinants (mecA,vanA, andvanB) in positive blood culture broths.

Direct identification of Gram-positive bacteria and resistance determinants from blood cultures using a microarray-based nucleic acid assay: in-depth analysis of microarray data for undetermined results

2015 ◽  
Vol 53 (7) ◽  
Author(s):  
Seon Young Kim ◽  
Yun Ji Hong ◽  
Sang Mee Hwang ◽  
Taek Soo Kim ◽  
Jae-Seok Kim ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Blood Culture ◽  
Blood Cultures ◽  
Automated System ◽  
Correct Identification ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Resistance Determinants ◽  
Depth Analysis ◽  
Nucleic Acid Assay

AbstractThe Verigene Gram-Positive Blood Culture (BC-GP) nucleic acid assay (Nanosphere, Inc., Northbrook, IL, USA) is a newly developed microarray-based test with which 12 Gram-positive bacterial genes and three resistance determinants can be detected using blood culture broths. We evaluated the performance of this assay and investigated the signal characteristics of the microarray images.At the evaluation stage, we tested 80 blood cultures that were positive for various bacteria (68 bacteria covered and 12 not covered by the BC-GP panel) collected from the blood of 36 patients and 44 spiked samples. In instances where the automated system failed and errors were called, we manually inspected microarray images, measured the signal intensities of target spots, and reclassified the results.With the manual analysis of the microarray images of 14 samples for which error calls were reported, we could obtain correct identification results for 12 samples without the need for retesting, because strong signals in the target spots were clearly discriminable from background noise. With our interpretation strategy, we could obtain 97.1% sensitivity and 100% specificity for bacterial identification by using the BC-GP assay. The two unidentified bacteria were viridans group streptococci, which produced weaker target signals. During the application stage, among 25 consecutive samples positive for Gram-positive bacteria, we identified two specimens with error calls asWith help of the manual review of the microarray images, the BC-GP assay could successfully identify species and resistance markers for many clinically important Gram-positive bacteria.

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