A simple iodometric spot test for detecting beta-lactamase activity in Haemophilus influenzae was compared with the capillary procedure for detecting beta-lactamase and the Bauer-Kirby disk susceptibility procedure. Isolates were classified similarly by all three procedures.

A Klebsiella pneumoniae isolate was identified that had reduced susceptibility to several expanded-spectrum cephalosporins and imipenem. That isolate produced a chromosome-encoded SHV-type beta-lactamase, SHV-38, that had an alanine to valine substitution in position Ambler 146 compared to beta-lactamase SHV-1. The kinetic parameters for purified beta-lactamases SHV-38 and SHV-1 showed that the...

Clavulanate is a broad-spectrum beta-lactamase inhibitor, with activity against many of the chromosomally and plasmid-mediated beta-lactamases of both Gram-positive and Gram-negative bacteria. Although clavulanate has minimal antibacterial activity in vitro, accumulating evidence suggests that it may have an effect on pathogenic bacteria regardless of beta-lactamase production. Like other beta-...

The specific activity, substrate profile, response to inhibitors, inducibility, and cellular localization of the beta-lactamase produced by an ampicillin-resistant strain of Haemophilus influenzae type B were investigated. In these properties the enzyme resembles beta-lactamases produced by other gram-negative bacilli more closely than those produced by gram-positive organisms. It is quite simi...

Four new beta-lactam antimicrobials, ceftriaxone, cefotiam, cefonicid, and mecillinam, were evaluated in vitro against 72 beta-lactamase-negative and 26 beta-lactamase-positive isolates of Neisseria gonorrhoeae. Ceftriaxone was the most active of the antimicrobials tested. It inhibited all isolates, regardless of beta-lactamase activity, at a concentration of less than or equal to 0.015 microgr...

The in vitro activities of three new beta-lactam antimicrobial agents, cefodizime, ceftazidime, and aztreonam (formerly azthreonam), were compared with those of cefotaxime, cefuroxime, cefoxitin, and penicillin against 100 beta-lactamase-negative and 42 beta-lactamase-positive Neisseria gonorrhoeae strains. The three new antimicrobial agents showed excellent activity against N. gonorrhoeae rega...

BACKGROUND & OBJECTIVES AmpC beta-lactamases are Group I cephalosporinases that confer resistance to a wide variety of beta-lactam drugs. Plasmid mediated AmpC beta-lactamases has been discovered most frequently in isolates of Klebsiella pneumoniae, K. oxytoca, Salmonella, Proteus mirabilis and Escherichia coli. The present study was undertaken to study the occurrence of multidrug resistant and...

Mycobacterium fortuitum is a fast-growing Mycobacterium species which produces a beta-lactamase involved in the intrinsic resistance of the microorganism to beta-lactam antibiotics. An anti-beta-lactamase serum against the purified enzyme was raised in rabbits. Antibody binding was specific for native beta-lactamase, and enzyme activity was partially inhibited by the serum; furthermore, cross-r...

The fourth generation cephalosporins, cefpirome and cefepime, demonstrate better activity against strains of Enterobacter cloacae with derepressed beta-lactamase than the third generation compounds cefotaxime and ceftriaxone. Several methodological refinements were used to measure the parameters, predicted by the Zimmermann-Rosselet equation to be important in the efficacy of beta-lactams. Oute...

Previous studies have reported beta-lactamase-mediated penicillin resistance in Fusobacterium nucleatum, but no beta-lactamase gene has yet been identified in this species. An F. nucleatum subsp. polymorphum strain resistant to penicillin and amoxicillin was isolated from a human periodontitis sample. DNA cloning and sequencing revealed a 765-bp open reading frame encoding a new class D beta-la...