Penicillinase-resistant Penicillins Research Articles

UNMASKING OF FALSE-NEGATIVE BLOOD CULTURES IN PATIENTS RECEIVING NEW PENICILLINS.

THE ORIGINAL INVESTIGATIONS of the new penicillinase-resistant penicillins demonstrated that their antimicrobial activity could be destroyed by sufficiently large concentrations of Bacillus cereus penicillinase. 1 During the course of experiments dealing with the bactericidal activity of such penicillins, it was essential to antagonize residual antibiotic in subcultures to avoid false-negatives. For this to be accomplished, the actual concentration of penicillinase necessary for this purpose had to be established. This information also could be extended to clinical laboratories where blood cultures are made from patients under treatment with these drugs. We have therefore investigated this problem via a study of ratios of B cereus penicillinase to penicillin required for inactivation of four penicillinase-resistant penicillins. For practical laboratory applications it is probably fortunate that B cereus penicillinase, which is easily obtainable, is more potent than staphylococcal penicillinase against resistant penicillins. 1 It is the purpose of this paper to report these studies.

Clinical and Laboratory Studies of Sodium Diphenicillin

Introduction The purpose of this paper is to present data on the antibacterial activity of a new penicillinase-resistant penicillin and its absorption from the gastrointestinal tract. The drug is sodium diphenicillin (sodium 2-biphenylylpenicillin) 1 and is manufactured from penicillanic acid. Material and Methods Sodium diphenicillin was supplied to us by Smith Kline & French Laboratories as a white powder and labeled SK&F 12141. It is also known as Ancillin. It is highly soluble in water and is stable in high concentration in aqueous solution for at least ten days at 4 C. Its structural formula has been reported. 1 Bacteria Tested.— The group included 114 strains of mannitol-positive Staphylococcus aureus recovered from various clinical lesions in patients in the Cincinnati General and the Longview State Hospitals. Two strains (Nos. 48 and 49) were methicillin-resistant staphylococci kindly sent us by Dr. Patricia Jevons of the Staphylococcus Reference Laboratory, London, England. Strains

Persistence of staphylococcus to methicillin and oxacillin. Observations on two cases of endocarditis.

The new penicillinase-resistant semisynthetic penicillins methicillin and oxacillin have proved effective against staphylococci in vitro and in vivo. They are considered the answer to the staphylococcal problem. It has been observed that the antibacterial activity of the new penicillins is much inferior to that of benzylpenicillin since a large number of bacteria survived despite their action.1-3,7 In using methicillin at first and oxacillin lately we have been struck by the slowness of response, especially of the septicemia and endocarditis patients. In the 2 representative cases that we describe here, Staphylococcus was isolated from the blood stream while the patients were under treatment with methicillin or oxacillin. A large number of survivors have been observed in in vitro experiments in high concentrations of the antibiotics. Report of Cases Case 1.— This patient was a 19-year-old male with a congenital aortic stenosis. Staphylococcal endocarditis was diagnosed in January, 1961. The fever

Isoxazolyl penicillins and penicillinase.

THE isoxazolyl series of penicillinase-resistant penicillins has been described by Doyle et al.1. Many members of this series are acid-stable, and considerably more active against staphylococci than methi-cillin. Three members of this series (BRL.1400 5-methyl-3-phenyl-4-isoxazolylpenicillin, BRL. 1577 5-methyl-3-p-chlorphenyl-4-isoxazolylpenicillin and BRL.1621 5-methyl-3-o-chlorphenyl-4-isoxazolylpenicillin) have been investigated for antibacterial activity and for stability to, induction of, affinity for, and inhibitory action on, the penicillinases of Staph. aureus and B. cereus.