The activity of temocillin against Enterobacteriaceae, Pseudomonas and Haemophilus influenzae

The in vitro antimicrobial activity of temocillin against 130 strains of Enterobacteriaceae and 27 strains of Pseudomonas and other related Gram-negative organisms was compared with carbenicillin, mezlocillin and piperacillin. Temocillin was compared with ampicillin against 76 strains of Haemophilus influenzae. More than 90% of Enterobacteriaceae including 65 carbenicillin-resistant strains were inhibited by 8 mg/L of temocillin. Pseudomonas spp. were less susceptible to temocillin than to the other 3 penicillins. 35 out of 38 strains of beta-lactamase-producing H. influenzae were inhibited by 2 mg/L of temocillin. But with 38 ampicillin-sensitive and non-beta-lactamase-producing ampicillin-resistant strains, temocillin was slightly less active than ampicillin. There was no significant enhancement of temocillin activity by clavulanic acid against 20 strains of Gram-negative rods producing characterised beta-lactamases. The resistance to plasmid-mediated and chromosomal beta-lactamase extracts was also studied by bioassay method. No enzyme extracts tested could hydrolyse temocillin except that from one Flavobacterium strain.