264 Mary Barber 



Production of penicillinase by staphylococci 



Kirby (1944) first extracted a potent penicillin inactivator 

 from 7 strains of Staphylococcus aureus, which he referred to 

 as "naturally resistant" since they had all been derived from 

 patients who had not received penicillin. In the following 

 year, Bondi and Dietz (1945) showed that all of 16 "naturally 

 resistant" strains of staphylococci produced a penicillin 

 inactivator, whereas in a previous study (Bondi and Dietz, 

 1944) they had shown that staphylococci which had acquired 

 resistance to penicillin in vitro did not. In the same year Gots 

 (1945) found that all of 53 penicillin-resistant strains oi Staph, 

 aureus isolated from patients produced a penicillin inacti- 

 vator, and concluded that there was a difference in the 

 mechanism of development of "in vitro acquired resistance 

 and in vivo acquired resistance". 



The properties of this penicillin inactivator were studied 

 by Kirby (1945) who extracted it by the acetone-ether 

 method used by Harper (1943) to obtain cell-free penicilhnase 

 from paracolon bacilli. He compared the product thus 

 isolated from penicillin-resistant Staph, aureus with the peni- 

 cillin-destroying enzymes isolated by Abraham and Chain 

 (1940) from Bacterium coli and an unidentified Gram-negative 

 rod, and by Harper (1943) from a paracolon bacillus, and 

 regarded the differences as superficial. 



Kirby (1945) regarded staphylococcal penicillinase as an 

 intracellular enzyme which Avas not liberated into the culture 

 fluid. Many subsequent workers agreed that staphylococcal 

 penicillinase was closely bound to the cells (Spink and Ferris, 

 1947; Gilson and Parker, 1948; Czekalowski, 1950), but 

 Housewright and Henry (1947) recorded one strain oi Staph, 

 aureus from which cell-free penicillinase could be isolated, 

 and Gots (1945) and Luria (1946) found penicillinase activity 

 in culture supernatants. Recently, Eriksen and Hansen 

 (1954) have reported the production of extracellular penicil- 

 linase by 8 strains of Staph, aureus. When overnight broth 

 cultures of these strains were filtered through gradocol mem- 



