scholarly journals Genetics of resistance in a non-beta-lactamase-producing gonococcus with relatively high-level penicillin resistance.

1986 ◽  
Vol 30 (6) ◽  
pp. 856-860 ◽  
Author(s):  
H Faruki ◽  
P F Sparling
Keyword(s):  
Penicillin Resistance ◽  
Beta Lactamase ◽  
Genetics Of Resistance ◽  
High Level

scholarly journals Overexpression of the MtrC-MtrD-MtrE Efflux Pump Due to an mtrR Mutation Is Required for Chromosomally Mediated Penicillin Resistance in Neisseria gonorrhoeae

2002 ◽  
Vol 184 (20) ◽  
pp. 5619-5624 ◽  
Author(s):  
Wendy L. Veal ◽  
Robert A. Nicholas ◽  
William M. Shafer
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Base Pair ◽  
Efflux Pump ◽  
Penicillin Resistance ◽  
Single Base ◽  
Base Pair Deletion ◽  
Resistance To Penicillin ◽  
Single Base Pair ◽  
High Level ◽  
Level Resistance

ABSTRACT The importance of the mtrCDE-encoded efflux pump in conferring chromosomally mediated penicillin resistance on certain strains of Neisseria gonorrhoeae was determined by using genetic derivatives of penicillin-sensitive strain FA19 bearing defined mutations (mtrR, penA, and penB) donated by a clinical isolate (FA6140) expressing high-level resistance to penicillin and antimicrobial hydrophobic agents (HAs). When introduced into strain FA19 by transformation, a single base pair deletion in the mtrR promoter sequence from strain FA6140 was sufficient to provide high-level resistance to HAs (e.g., erythromycin and Triton X-100) but only a twofold increase in resistance to penicillin. When subsequent mutations in penA and porIB were introduced from strain FA6140 into strain WV30 (FA19 mtrR) by transformation, resistance to penicillin increased incrementally up to a MIC of 1.0 μg/ml. Insertional inactivation of the gene (mtrD) encoding the membrane transporter component of the Mtr efflux pump in these transformant strains and in strain FA6140 decreased the MIC of penicillin by 16-fold. Genetic analyses revealed that mtrR mutations, such as the single base pair deletion in its promoter, are needed for phenotypic expression of penicillin and tetracycline resistance afforded by the penB mutation. As penB represents amino acid substitutions within the third loop of the outer membrane PorIB protein that modulate entry of penicillin and tetracycline, the results presented herein suggest that PorIB and the MtrC-MtrD-MtrE efflux pump act synergistically to confer resistance to these antibiotics.

scholarly journals Molecular aspects of high-level resistance to sulbactam-cefoperazone in Klebsiella oxytoca clinical isolates.

1996 ◽  
Vol 40 (9) ◽  
pp. 1988-1994 ◽  
Author(s):  
K Kimura ◽  
Y Arakawa ◽  
S Ohsuka ◽  
H Ito ◽  
K Suzuki ◽  
...  
Keyword(s):  
Klebsiella Oxytoca ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Point Of View ◽  
Clinical Isolates ◽  
Beta Lactamase ◽  
Beta Lactamases ◽  
Molecular Aspects ◽  
High Level ◽  
Level Resistance

Nine Klebsiella oxytoca strains which demonstrated resistance to the combination of sulbactam and cefoperazone were isolated from geographically separate hospitals in Japan in 1995. Among them, K. oxytoca SB23 showed high-level resistance to sulbactam-cefoperazone (MIC > 128 micrograms/ml) and aztreonam (MIC, 128 micrograms/ml). The sulbactam-cefoperazone resistance was not transferred from strain SB23 to Escherichia coli CSH2 by conjugation, beta-Lactamase RbiA, produced by strain SB23, was purified, and the molecular mass was estimated to be 29 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Kinetic parameters for RbiA revealed that cefoperazone and aztreonam were hydrolyzed efficiently by this enzyme. Moreover, ceftazidime and imipenem were also hydrolyzed weakly by RbiA, although strain SB23 did not show any resistance to these agents. Clavulanate, sulbactam, and tazobactam failed to block the hydrolysis of cefoperazone by RbiA. The structural gene of RbiA (blaRBI) was cloned and sequenced, and the deduced amino acid sequence of RbiA demonstrated high-level similarities to those of the beta-lactamases found in K. oxytoca D488, E23004, and plasmid-mediated MEN-1, which have been classified into Bush functional group 2be. Although RbiA demonstrates high-level molecular similarity to the enzymes in group 2be, from an enzymological point of view, this enzyme might be differentiated from the enzymes in that group. Hybridization analysis revealed that beta-lactamase genes highly similar to blaRBI were generally encoded on the chromosome of the sulbactam-cefoperazone-resistant clinical isolates of K. oxytoca tested in the study, despite their different derivations. This observation suggests that sulbactam-cefoperazone-resistant A. oxytoca strains which produce RbiA-type beta-lactamases have been proliferating in many hospitals in Japan.

scholarly journals Genetics of high level penicillin resistance in clinical isolates ofStreptococcus pneumoniae

1995 ◽  
Vol 126 (3) ◽  
pp. 299-303 ◽  
Author(s):  
Victoria A Barcus ◽  
Kiran Ghanekar ◽  
Maggie Yeo ◽  
Tracey J Coffey ◽  
Christopher G Dowson
Keyword(s):  
Clinical Isolates ◽  
Penicillin Resistance ◽  
High Level

scholarly journals Vancomycin and high-level aminoglycoside resistance in Enterococcus species

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Seyda Ozarslan Kurtgoz ◽  
Burcin Ozer ◽  
Melek Inci ◽  
Nizami Duran ◽  
Erkan Yula
Keyword(s):  
Vancomycin Resistance ◽  
Automated System ◽  
Diffusion Method ◽  
Beta Lactamase ◽  
Aminoglycoside Resistance ◽  
Disk Diffusion Method ◽  
Gradient Diffusion ◽  
Gentamicin Resistance ◽  
Polymerase Chain ◽  
High Level

The aim of the study was to investigate vancomycin and high-level aminoglycoside resistance (HLAR) in <em>Enterococcus</em> species by phenotypic and genotypic methods. A hundred <em>Enterococcus</em> strains were included in the study. Antimicrobial susceptibilities of strains were investigated by automated system, betalactamase production was investigated by nitrocefin disks, vancomycin resistance and HLAR were investigated by gradient diffusion method (GDM) and disk diffusion method, respectively. For detection of vancomycin and high-level gentamicin resistance (HLGR) genes, polymerase chain reaction was used. Teicoplanin linezolid, vancomycin, ampicillin, penicillin are the most susceptible antibiotics and strains were detected not to produce beta lactamase. Vancomycin resistance was detected in ten isolates by automated system and in only five isolates by GDM. Five isolates carrying <em>VanA</em> gene were determined. The ratio of HLGR and high-level streptomycin resistance was found 40 and 63% respectively. <em>aac (6’)-1eaph (2’’)-1a</em> gene was detected in 58% of strains. <em>E. faecium</em> strains were found more resistant to the antibiotics than the other species. Beta lactamase was detected in none of strains. The automated system detected vancomycin resistance in more strains than GDM. Therefore it is concluded that strains, which were detected to be resistant to vancomycin, should be confirmed by GDM. The ratio of <em>VanA</em> gene in strains is consistent with other studies. The HLAR ratio was found in about half of strains. The ratio of<em> aac(6’)-1e-aph(2’’)-1a</em> gene, which is the most reported gene in our country and other countries and one of the HLGR genes investigated in our study, was detected 58%.

scholarly journals A TEM-derived extended-spectrum beta-lactamase in Pseudomonas aeruginosa.

1996 ◽  
Vol 40 (11) ◽  
pp. 2488-2493 ◽  
Author(s):  
P Mugnier ◽  
P Dubrous ◽  
I Casin ◽  
G Arlet ◽  
E Collatz
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Clinical Strain ◽  
Beta Lactamase ◽  
Beta Lactam ◽  
Aminoglycoside Resistance ◽  
Double Mutation ◽  
Extended Spectrum Beta Lactamase ◽  
Beta Lactam Antibiotics ◽  
Extended Spectrum ◽  
High Level

A clinical strain of Pseudomonas aeruginosa, PAe1100, was found to be resistant to all antipseudomonal beta-lactam antibiotics and to aminoglycosides, including gentamicin, amikacin, and isepamicin. PAe1100 produced two beta-lactamases, TEM-2 (pI 5.6) and a novel, TEM-derived extended-spectrum beta-lactamase called TEM-42 (pI 5.8), susceptible to inhibition by clavulanate, sulbactam, and tazobactam. Both enzymes, as well as the aminoglycoside resistance which resulted from AAC(3)-IIa and AAC(6')-I production, were encoded by an 18-kb nonconjugative plasmid, pLRM1, that could be transferred to Escherichia coli by transformation. The gene coding for TEM-42 had four mutations that led to as many amino acid substitutions with respect to TEM-2: Val for Ala at position 42 (Ala42), Ser for Gly238, Lys for Glu240, and Met for Thr265 (Ambler numbering). The double mutation Ser for Gly238 and Lys for Glu240, which has so far only been described in SHV-type but not TEM-type enzymes, conferred concomitant high-level resistance to cefotaxime and ceftazidime. The novel, TEM-derived extended-spectrum beta-lactamase appears to be the first of its class to be described in P. aeruginosa.

scholarly journals Molecular characterization of extended-spectrum beta-lactamase producing Enterobacteriaceae in a Saudi Arabian tertiary hospital

2014 ◽  
Vol 8 (03) ◽  
pp. 282-288 ◽  
Author(s):  
Hoda Hassan ◽  
Baha Abdalhamid
Keyword(s):  
Tertiary Hospital ◽  
Multidrug Resistant ◽  
Beta Lactamase ◽  
M Gene ◽  
Extended Spectrum Beta Lactamase ◽  
E Coli ◽  
Extended Spectrum ◽  
Vitek 2 ◽  
High Level

Introduction: The aim of this study was to determine the prevalence of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), and Proteus mirabilis (P. mirabilis). In addition, different methods for detection of these enzymes, including the newly introduced CHROMagar ESBL, were evaluated. Methodology: A total of 382 Enterobacteriaceae clinical isolates were obtained from King Fahad Specialist Hospital – Dammam, during 2011 and screened for production of ESBL using advanced expert system of Vitek 2, CHROMagar and ESBL-E-strips. PCR assay was used to detect blaTEM, blaSHV, and blaCTX-M genes. Susceptibility to a panel of antibiotics was determined. Results: The overall proportion of ESBL-producing enterobacterial isolates was 30.6%, which was higher in E. coli (35.8%) than in K. pneumoniae (25.7%). ESBL genotypes showed remarkable increase in the CTX-M (97.4%) compared to SHV (23.1%). The predominant ESBL was CTX-M- 15 (92.1 %). No TEM ESBL was detected in this study. The Vitek2 showed the highest sensitivity (100%), and the CHROMagar had the lowest specificity (97.3%) compared to the molecular method. All isolates were susceptible to imipenem and meropenem. Conclusions: This study confirms a high level of blaCTX-M positive ESBL isolates are circulating in the Eastern Province of Saudi Arabia. The trend of a multidrug-resistant profile associated with the recovery of the blaCTX-M gene is alarming.

scholarly journals Increased Incidence of .BETA.-lactamase-plasmid Negative, High Level Methicillin-Resistant Staphylococcus aureus (MRSA).

1996 ◽  
Vol 43 (3) ◽  
pp. 199-206 ◽  
Author(s):  
TOSHINOBU YOKOYAMA ◽  
JUNICHI HONDA ◽  
TOMOTAKA KAWAYAMA ◽  
KATSUNARI KAJIMURA ◽  
KOTARO OIZUMI
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Beta Lactamase ◽  
Methicillin Resistant ◽  
High Level
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