The action and interaction of benzylpenicillin and gentamicin on Streptococcus faecalis was studied using mainly turbidimetric methods. The minimum antibacterial concentration (MAC) of each antibiotic lay considerably below the conventionally determined minimum inhibitory concentration, and levels of the two agents exceeding the MAC were necessary in order to obtain a synergic interaction. Evid...

Some biochemical properties of whole-cell penicillin amidohydrolase from Micrococcus luteus have been studied. This whole-cell enzyme showed its maximal activity at 36 degrees C at pH 7.5. It was found that the activation energy of this enzyme was 8.03 kcal (ca. 33.6 kJ) per mol, and this amidohydrolase showed first-order decay at 36 degrees C. The penicillin amidohydrolase was deactivated rapi...

Linear regression analysis was used to compare penicillin MICs determined with 3,129 recent clinical isolates of Streptococcus pneumoniae to MICs obtained with nine other beta-lactam antimicrobial agents. A strong correlation between penicillin MICs and those obtained with other beta-lactams was demonstrated. It may be possible to test penicillin and use MICs obtained with penicillin to predict...

Linear regression analysis was used to compare penicillin MICs determined with 3,129 recent clinical isolates of Streptococcus pneumoniae to MICs obtained with nine other beta-lactam antimicrobial agents. A strong correlation between penicillin MICs and those obtained with other beta-lactams was demonstrated. It may be possible to test penicillin and use MICs obtained with penicillin to predict...

BACKGROUND Penicillin-resistant strains of Streptococcus pneumoniae are now found worldwide, and strains with resistance to cephalosporin are being reported. The appropriate antibiotic therapy for pneumococcal pneumonia due to resistant strains remains controversial. METHODS To examine the effect of resistance to penicillin and cephalosporin on mortality, we conducted a 10-year, prospective s...

Gale and his group have shown that (1) staphylococci grown "deficient" in glutamic acid can concentrate the free amino acid inside the cells, provided a source of eneigy is present (Gale, 1947; Taylor, 1947); (2) penicillin, in growthinhibitory amounts, prevents the uptake of glutamic acid by staphylococci if the organisms are first grown for a short period in the presence of the antibiotic (Ga...