In Vivo Studies on Staphylococcal Penicillinase

Area of Science:

• Microbiology
• Biochemistry

Background:

• Penicillin resistance in Staphylococcus is a significant clinical concern.
• Penicillinase is widely assumed to be responsible for this resistance in vivo.
• Quantitative data supporting this assumption have been lacking.

Purpose of the Study:

• To determine the amounts of staphylococcal penicillinase present in vivo during established infections.
• To quantitatively assess the role of penicillinase in penicillin resistance of staphylococci.

Main Methods:

• Infection was established in mice using penicillin-resistant staphylococci.
• Staphylococcal penicillinase levels were measured in the infected tissue.
• Penicillinase activity was assessed in the absence of known inducing conditions.

Main Results:

• Significant amounts of staphylococcal penicillinase were detected in the tissue of infected mice.
• The measured penicillinase levels were adequate to neutralize substantial quantities of penicillin.
• Penicillinase was present even without conditions known to induce its production.

Conclusions:

• The study provides quantitative evidence that staphylococcal penicillinase is present in sufficient amounts in vivo to account for high levels of penicillin resistance.
• These findings confirm the role of penicillinase in mediating bacterial resistance to penicillin during infection.