we introduce a new smooth, non-toxic, biocompatible method for cross-linking of gum tragacanth (gt), a polysaccharide of natural origin, in order to serve as a new supporting matrix for immobilization systems.  the modified gum is used as a matrix for the catalysis of the conversion of benzyl penicillin to 6-aminopenicillanic acid (6-apa) by means of escherichia coli atcc11105 with penicillin g...

Between 1966 and 1978 the sensitivities of strains of Neisseria gonorrhoeae (70-80 strains in each year) to penicillin, thiamphenicol, and spectinomycin were tested. For penicillin the proportion of less sensitive strains increased from 21% in 1976 to 41% in 1978 and for thiamphenicol from 10% to 18% over the same period. All the strains proved to be sensitive to spectinomycin. A significant co...

Core tonsillar cultures were obtained from 40 children with recurrent tonsillitis treated with either penicillin or cefdinir. Group A beta-hemolytic streptococci were isolated from 11 penicillin- and 3 cefdinir-treated (P < 0.001) patients. beta-Lactamase producers were recovered from 17 penicillin- and 3 cefdinir-treated (P < 0.01) patients. Inhibiting alpha-hemolytic streptococci were isolate...

Alterations within the penicillin-binding domain of penicillin-binding protein (PBP) genes pbp1a, pbp2b, and pbp2x were determined for 15 Canadian isolates of Streptococcus pneumoniae. All penicillin-nonsusceptible S. pneumoniae isolates showed a variety of PBP 2X substitutions and contained a Thr445-Ala change after the PBP 2B SSN motif. Only isolates for which penicillin MICs were > or =0.5 m...

Although the rate of acylation of a penicillin-resistant form of Streptococcus pneumoniae penicillin-binding protein 2x (PBP2x) by ceftaroline is 80-fold lower than that of its penicillin-sensitive counterpart, it remains sufficiently high (k(2)/K = 12,600 M(-1) s(-1)) to explain the sensitivity of the penicillin-resistant strain to this new cephalosporin. Surprisingly, the Actinomadura R39 DD-...

Heteroresistance to beta-lactam antibiotics has been mainly described for staphylococci, for which it complicates diagnostic procedures and therapeutic success. This study investigated whether heteroresistance to penicillin exists in Streptococcus pneumoniae. Population analysis profile (PAP) showed the presence of subpopulations with higher penicillin resistance in four of nine clinical pneumo...

BACKGROUND The absence of commercially available penicilloyl-polylysine (PPL) for most of the last decade severely hampered the practice of penicillin allergy evaluation because skin testing without PPL is reported to have a poor negative predictive value (NPV). OBJECTIVE To determine the safety and NPV of skin testing without PPL using only penicillin G followed by a 3-dose graded challenge ...

Sir, Reduced susceptibility of Neisseria meningitidis to penicillin (MICs 0.12 mg/L) in the UK was reported by Jones & Sutcliffe in 1990 to be at a level of 3%, comparable to that found in 1987. We have recently undertaken an in vitro study to investigate the susceptibility of meningococci from our collection of strains, to a variety of antimicrobial agents, including penicillin, using BSAC met...

Alignment of the amino acid sequence of penicillin-binding protein 5 (PBP5) with the sequences of other members of the family of active-site-serine penicillin-interacting enzymes predicted the residues playing a role in the catalytic mechanism of PBP5. Apart from the active-site (Ser44), Lys47, Ser110-Gly-Asn, Asp175 and Lys213-Thr-Gly were identified as the residues making up the conserved box...

Background and purpose: Highly consumption of antibiotics and their entrance into the environment has increased concerns all over the world. These compounds enter to the environment through an incomplete metabolism and a considerable amount of them cannot be removed using usual waste filtration systems. Therefore, the present study aimed to investigate the feasibility of using ultraviolet radia...