Cefotaxime is more active than six other cephalosporins against 150 cephalothin-resistant Enterobacteriaceae strains and is the only drug which is more active than ampicillin against Haemophilus. It shows a potentially useful activity against Pseudomonas.Cefotaxime is the sodium salt of 7-[(2-(2-amino-4-thiazolyl)-2(z)-methoxy-imino) acetamido] cephalosporanic acid. The antibacterial spectrum of the compound is considerably broader than that of known cephalosporins (8). The increase in resistance among the Enterobacteriaceae against cephalothin (11) and the emergence of ,B-lactamase-producing Haemophilus strains (9) has increased the demand for new antibiotics. Among the newer cephalosporin-like antibiotics, the most promising are cefamandole and cefuroxime with good activity on Haemophilus and most of the Enterobacteriaceae (5, 12) and cefoxitin with good activity on Bacteroides fragilis (13) and on the Enterobacteriaceae, with the exception of Enterobacter (3, 15); finally, cefazaflur was shown to be very active against the Enterobacteriaceae with the exception of Serratia (14).Cefotaxime has several advantages over the other newer cephalosporins. It has been shown by others to be more active than previous cephalosporins, including cefuroxime and cefoxitin, against cephalothin-susceptible strains and Haemophilus influenzae (1,7). Its stability against ,8-lactamase hydrolysis is comparable to that of cefuroxime and cefoxitin, but cefotaxime is the most active inhibitor of type 1 ,B-lactamase (6).In contrast, it seems to be less active than cefoxitin against Bacteroides fragilis (1).In accordance with these publications, it is clear from this study that cefotaxime is also very active against cephalothin-resistant Enterobacteriaceae with an activity that is at least 21 times greater than that of the second most active drug and the only drug with excellent activity against one of the most resistant species, namely, Serratia. It is also at least 45 times more active than the other cephalosporins against Haemophilus strains and the only one which is even

The minimal inhibitory concentration of temocillin (BRL 17421) against 476 clinical isolates was determined by an agar dilution method. Temocillin was active against most of the Enterobacteriaceae, Haemophilus, and Neisseria strains tested. The compound showed low activity or was inactive against Bacteroides, Campylobacter, Acinetobacter, Pseudomonas, and Staphylococcus aureus strains. Within each species, individual strains showed a high degree of uniformity in their susceptibility to temocillin; the drug concentrations that inhibited the growth of 90% of organisms were the same or close to those which inhibited the growth of 50% of organisms. In contrast, the same strains showed a very wide range of susceptibility to the other antibiotics tested, including third-generation cephalosporins. Against strains of Enterobacteriaceae highly susceptible to thirdgeneration cephalosporins, temocillin was considerably less active than cefotaxime, ceftazidime, and moxalactam, although it was more active than cefazolin and piperacillin. Against certain strains of Enterobacter and Citrobacter resistant to third-generation cephalosporins, temocillin was more active than cefotaxime and ceftazidime. An increase in the inoculum size did not alter the activity of temocillin, indicating that the compound has high stability to ,-lactamases. The minimal lethal concentration was also very similar to the minimal inhibitory concentration when an inoculum of 105 colony-forming units was used.Temocillin (BRL 17421) is a new semisynthetic ,3-lactam antibiotic that is highly stable to the bacterial P-lactamases and is active against most Enterobacteriaceae, Haemophilus, and Neisseria strains (3, 4). We investigated the in vitro activity of temocillin and compared it with the activities of cephalothin, cefotaxime, ceftazidime, moxalactam, and piperacillin against a wide range of recent clinical isolates.

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The in vitro activity of ceftazidime was determined using an agar dilution technique and compared with that of cefotaxime and moxalactam against 559 clinically important isolates. Ceftazidime showed poor activity against Bacteroides and Campylobacter, moderate activity against Staphylococcus aureus and excellent activity against Haemophilus, Aeromonas and the Enterobacteriaceae. 91% of 324 cephalothin-resistant Enterobacteriaceae were inhibited at a concentration of 1 mg/l. Ceftazidime was the most active drug against Acinetobacter. It also showed exceptional activity against Pseudomonas, inhibiting 90% of the strains at a concentration of 4 mg/l. A significant inoculum effect was only seen with inocula of 10(6) cfu or higher, and depended on the strain tested and the methodology employed.

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