Penicillin-resistant and Penicillin-dependent Staphylococcal Variants

Penicillin-resistant and penicillin-tolerant mutants of group A Streptococci.

Penicillin-resistant and penicillin-tolerant mutants have been isolated from group A streptococci mutagenized by ethyl methane sulfonate. The resistant mutants had an elevated minimal growth inhibitory concentration for benzylpenicillin (minimal inhibitory concentration, 0.2 microgram/ml, as compared with the minimal inhibitory concentration of 0.006 microgram/ml in the penicillin-susceptible p...

Penicillin-resistant Streptococcus Pneumoniae

Streptococcus pneumoniae is a major cause of pneumonia, meningitis, septicemia, acute otitis media, and other serious infections, severely affecting infants, young children, and the elderly. In the past, S. pneumoniae was uniformly susceptible to penicillin, which remained the drug of choice for serious infections. However, since the mid-1960s, resistance to penicillin, which was first reported...

Penicillin resistant pneumococcus.

Resistance to other antimicrobial agents and chloramphenicol has also been reported. 4,5 Multiple resistant strains have been responsible for infection with a high mortality rate. 5 To our knowledge, isolation of penicillin resistant pneumococci has not been documented in this region. We report the isolation of a penicillin resistant strain from the throat of an eleven-month old baby boy and th...

Properties of a Penicillin Inactivator Extracted from Penicillin-resistant Staphylococci.

Correlation of penicillin minimum inhibitory concentrations and penicillin zone edge appearance with staphylococcal beta-lactamase production.

Production of staphylococcal beta-lactamase was shown to be correlated with penicillin G minimum inhibitory concentrations (MICs) of greater than 0.05 microgram/ml for 97% of the Staphylococcus aureus and 99% of the Staphylococcus epidermidis strains tested. However, it is important to note that of the isolates for which MICs were equal to or less than 0.05 micro/ml, a significant percentage (1...