Disease relevance of blaZ

• With several different vectors, attempts were made to establish blaZ, a Staphylococcus aureus beta-lactamase gene, in Bacillus subtilis [1].
• Nucleotide sequence and expression of the beta-lactamase gene from Staphylococcus aureus plasmid pI258 in Escherichia coli, Bacillus subtilis, and Staphylococcus aureus [2].
• However, clones containing only the small amount of DNA found necessary for expression of ampicillin resistance in E. coli did not express beta-lactamase in S. aureus [3].
• These data demonstrate the discrepancies between surface and core cultures in the isolation of anaerobic bacteria, and raise the question whether surface cultures can accurately predict the presence of beta-lactamase-producing organisms or other pathogens in the recurrently infected tonsil [4].
• Beta-lactamase resistance has increased significantly being encountered in Neisseria, Haemophilus, Enterobacteriaceae, and Pseudomonas species [5].

High impact information on blaZ

• Staphylococcus aureus isolates that produced the A and C variants of staphylococcal beta-lactamase were associated with infections following cefazolin and cefamandole prophylaxis, respectively [6].
• X-ray analysis of the NMC-A beta-lactamase at 1.64-A resolution, a class A carbapenemase with broad substrate specificity [7].
• The base sequence of the ribosome binding site region of the Gram-positive Staphylococcus aureus beta-lactamase gene has been determined [8].
• Unique features in the ribosome binding site sequence of the gram-positive Staphylococcus aureus beta-lactamase gene [8].
• The leader peptide sequence of 24 amino acids which precedes the NH2 terminus of extracellular S. aureus beta-lactamase has also been established [8].

Chemical compound and disease context of blaZ

• Plasmid diploids were constructed in Staphylococcus aureus to study the effect of the repressor of methicillin resistance (MecI) on the synthesis of both beta-lactamase and the beta-lactamase repressor (BlaI) [9].
• Pre-steady state beta-lactamase kinetics. Observation of a covalent intermediate during turnover of a fluorescent cephalosporin by the beta-lactamase of STaphylococcus aureus PC1 [10].
• Beta-Lactam-beta-lactamase-inhibitor combinations are active in experimental endocarditis caused by beta-lactamase-producing oxacillin-resistant staphylococci [11].
• We have previously reported the transfer between Enterococcus faecalis strains of a multiresistance chromosomal element (beta-lactamase positive and resistance to erythromycin, gentamicin, mercuric chloride, streptomycin, and tetracycline) which we have tentatively designated Tn5385 [12].
• The activities of LY163892 and cefaclor were, however, highly inoculum dependent against beta-lactamase-positive Haemophilus influenzae and Staphylococcus aureus; that of cefuroxime was not [13].

Biological context of blaZ

• The qacA/B and blaZ probes hybridized to plasmids of similar size in three isolates [14].
• Similarly, a pC194-based shuttle vector (pGX318) containing the 5' end of blaZ (including the promoter and the coding region for the signal sequence and the first few amino acids of the mature protein) was unable to transform B. subtilis [1].
• Patterns of induction are influenced by the host strain and are slightly different from previous reports using the blaZ gene as reporter gene [15].
• Nucleotide sequence of the Staphylococcus aureus PC1 beta-lactamase gene [16].
• Kinetic measurements and electrospray mass spectrometry revealed that the first and third generation cephalosporins form stable acyl-enzyme complexes, except for the chromogenic cephalosporin, nitrocefin, which after acylating the enzyme undergoes hydrolysis at a 1000-fold slower rate than that with wild-type beta-lactamase [17].

Anatomical context of blaZ

• These types include combinations of agents that inhibit bacterial cell wall synthesis with aminoglycosidic aminocyclitols, the use of beta-lactamase inhibitors in combination with beta-lactam antibiotics, and the administration of agents that act on sequential steps in one of the bacterial metabolic or synthetic pathways [18].
• Failure to eradicate streptococci from patients can occasionally lead to rheumatic fever and rarely to glomerulonephritis. beta-lactamase-producing strains of aerobic and anaerobic bacteria in inflamed tonsils have been associated with increased failure rates of penicillins in the eradication of these infections [19].
• When 2 clinical strains of plasmid-mediated penicillin-resistant Staphylococcus aureus were treated with 1 mM sodium ascorbate for 6 h, 12-35% colony-forming units (CFU) irreversibly lost their ability to produce beta-lactamase [20].
• The emergence of penicillin and multidrug-resistant pneumococci and beta-lactamase-producing strains of H influenzae and M catarrhalis have special importance for the management of infections of the middle ear [21].
• Beta-lactamase, the bacterial enzyme that can inactivate penicillins, cephalosporins and related antibiotics, can function outside the cell or in the periplasmic space [22].

Associations of blaZ with chemical compounds

• In the three other BC and penicillin-resistant strains, the qacA/B and blaZ genes were located on separate plasmids [14].
• N-Carboxylated lysine also catalyzes hydrolytic deacylation of the acyl-enzyme species in the beta-lactamase [23].
• The beta-lactamase genes could be transferred to enterococcal and staphylococcal recipients from WH257 and DEL by conjugation or transformation with selection for gentamicin resistance [24].
• MecI-mediated repression of the synthesis of beta-lactamase was shown by reduction in the specific activity of nitrocefinase in bacteria containing a plasmid carrying mecI but not when containing the same plasmid deleted for mecI [9].
• Most examples of antibiotic antagonism are those in which a bacteriostatic agent renders a bactericidal agent "static." Another type of antagonism occurs when cefoxitin (which has a propensity to induce beta-lactamase production) is combined with another beta-lactam antibiotic [18].

Other interactions of blaZ

• Complete pbp2 sequences were determined for three BORSA, corresponding to ST25, ST1 and ST47, which were selected on the basis of lacking blaZ-encoded beta-lactamase [25].
• Either inducible beta-lactamase regulatory genes blaR1-blaI or homologous regulatory genes mecR1-mecI, which control mecA expression, acted as compensatory elements, permitting the maintenance and expression of plasmid-carried mecA [26].
• A novel plasmid (designated pUB102) harbouring far1, tetK and blaZ was characterised and partially sequenced [27].
• The pre-steady state kinetics of the hydrolysis of sodium 3-dansylamidomethyl-7-beta (thienyl-2')-acetamidoceph-3-em-4-oate, catalyzed by the beta-lactamase of Staphylococcus aureus PC1, has been studied by the stopped flow method [10].

Analytical, diagnostic and therapeutic context of blaZ

• 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 [28].
• The preparation, crystallization and low-resolution structure determination of beta-lactamase (EC 3.5.2.6, 'penicillinase') from Staphylococcus aureus is described [29].
• Animal experiments suggested that mezlocillin may exhibit a therapeutic effect against beta-lactamase-producing staphylococci under certain conditions in vivo which prevent build-up of exoenzyme [30].
• The vast majority of the microorganisms tested had reduced susceptibility to piperacillin (minimum inhibitory concentration (MIC) range 0.12- greater than 256 mg/l) due to beta-lactamase production [31].
• The polymicrobial aerobic-anaerobic flora of tracheostomy site wound infection, and the presence of beta-lactamase-producing bacteria in most of these infections, may have important implications for their management [32].

References